Performance of large area xenon ion thrusters for orbit transfer missions

NASA Technical Reports Server (NTRS)

Rawlin, Vincent K.

1989-01-01

Studies have indicated that xenon ion propulsion systems can enable the use of smaller Earth-launch vehicles for satellite placement which results in significant cost savings. These analyses have assumed the availability of advanced, high power ion thrusters operating at about 10 kW or higher. A program was initiated to explore the viability of operating 50 cm diameter ion thrusters at this power level. Operation with several discharge chamber and ion extraction grid set combinations has been demonstrated and data were obtained at power levels to 16 kW. Fifty cm diameter thrusters using state of the art 30 cm diameter grids or advanced technology 50 cm diameter grids allow discharge power and beam current densities commensurate with long life at power levels up to 10 kW. In addition, 50 cm diameter thrusters are shown to have the potential for growth in thrust and power levels beyond 10 KW.

Nuclear Power Systems for Manned Mission to Mars

DTIC Science & Technology

2004-12-01

Brayton Cycle ..........................................................................30 c. Stirling Cycle ...specific mass as the power level increases. This graph also shows the upward scalability of Brayton and Rankine cycles , predicting that higher...Orbit, 1985), 79. 47Joseph A. Angelo, Jr. and David Buden, Space Nuclear Power, (Malabar, Florida: Orbit, 1985), 80. 30 b. Brayton Cycle

The Neuromuscular Qualities of Higher- and Lower-Level Mixed-Martial-Arts Competitors.

PubMed

James, Lachlan P; Beckman, Emma M; Kelly, Vincent G; Haff, G Gregory

2017-05-01

To determine whether the maximal strength, impulse, and power characteristics of competitive mixed-martial-arts (MMA) athletes differ according to competition level. Twenty-nine male semiprofessional and amateur MMA competitors were stratified into either higher-level (HL) or lower-level (LL) performers on the basis of competition grade and success. The 1-repetition-maximum (1RM) squat was used to assess lower-body dynamic strength, and a spectrum of impulse, power, force, and velocity variables were evaluated during an incremental-load jump squat. In addition, participants performed an isometric midthigh pull (IMTP) and 1RM bench press to determine whole-body isometric force and upper-body dynamic strength capabilities, respectively. All force and power variables were expressed relative to body mass (BM). The HL competitors produced significantly superior values across a multitude of measures. These included 1RM squat strength (1.84 ± 0.23 vs 1.56 ± 0.24 kg BM; P = .003), in addition to performance in the incremental-load jump squat that revealed greater peak power (P = .005-.002), force (P = .002-.004), and velocity (P = .002-.03) at each load. Higher measures of impulse (P = .01-.04) were noted in a number of conditions. Average power (P = .002-.02) and velocity (P = .01-.04) at all loads in addition to a series of rate-dependent measures were also superior in the HL group (P = .005-.02). The HL competitors' 1RM bench-press values approached significantly greater levels (P = .056) than the LL group's, but IMTP performance did not differ between groups. Maximal lower-body neuromuscular capabilities are key attributes distinguishing HL from LL MMA competitors. This information can be used to inform evidenced-based training and performance-monitoring practices.

Four-Tap RF Canceller Evaluation for Indoor In-Band Full-Duplex Wireless Operation

DTIC Science & Technology

2016-07-24

2.45 GHz with +20 dBm of total output power . This waveform and power level are representative of many handheld wireless devices that can be used for...to investigate a canceller’s performance with higher transmit power levels that are characteristic of wireless nodes that cover larger areas. Fig. 5...Four-Tap RF Canceller Evaluation for Indoor In-Band Full-Duplex Wireless Operation Kenneth E. Kolodziej and Bradley T. Perry MIT Lincoln Laboratory

Variable gain for a wind turbine pitch control

NASA Technical Reports Server (NTRS)

Seidel, R. C.; Birchenough, A. G.

1981-01-01

The gain variation is made in the software logic of the pitch angle controller. The gain level is changed depending upon the level of power error. The control uses low gain for low pitch activity the majority of the time. If the power exceeds ten percent offset above rated, the gain is increased to a higher gain to more effectively limit power. A variable gain control functioned well in tests on the Mod-0 wind turbine.

Multi-Kilowatt Power Module for High-Power Hall Thrusters

NASA Technical Reports Server (NTRS)

Pinero, Luis R.; Bowers, Glen E.

2005-01-01

Future NASA missions will require high-performance electric propulsion systems. Hall thrusters are being developed at NASA Glenn for high-power, high-specific impulse operation. These thrusters operate at power levels up to 50 kW of power and discharge voltages in excess of 600 V. A parallel effort is being conducted to develop power electronics for these thrusters that push the technology beyond the 5kW state-of-the-art power level. A 10 kW power module was designed to produce an output of 500 V and 20 A from a nominal 100 V input. Resistive load tests revealed efficiencies in excess of 96 percent. Load current share and phase synchronization circuits were designed and tested that will allow connecting multiple modules in parallel to process higher power.

Motivation and social contexts: a crossnational pilot study of achievement, power, and affiliation motives.

PubMed

Xu, Xiaoyan; Xu, Yangang; Mellor, David; Duan, Liqiong

2012-01-01

Previous research suggests that there is a relationship between social contexts (e.g., economic growth, engagement in wars) and motives within populations. In particular, high achievement motive is associated with subsequent economic growth, which in turn increases power motive. Increased national achievement and power motives have been argued to precede social changes that lead to decreased affiliation motives, and engagement in wars. The present study aimed to examine differences in achievement, power, and affiliation motives between 266 college students in China (a nation with sustained high economic growth) and 255 college students in the USA (a nation with previously strong but now slowing economic growth, and engaged in war). Analysis of personal strivings suggested that Chinese college students showed significantly higher levels of achievement motive than the American college students, but American college students showed significantly higher levels of affiliation motive than Chinese college students. Overall, males exhibited higher achievement motivation than females. No significant interaction effects were found for gender by location for any of the three motives. The findings are discussed in relation to previous research.

Sourcing of Steam and Electricity for Carbon Capture Retrofits.

PubMed

Supekar, Sarang D; Skerlos, Steven J

2017-11-07

This paper compares different steam and electricity sources for carbon capture and sequestration (CCS) retrofits of pulverized coal (PC) and natural gas combined cycle (NGCC) power plants. Analytical expressions for the thermal efficiency of these power plants are derived under 16 different CCS retrofit scenarios for the purpose of illustrating their environmental and economic characteristics. The scenarios emerge from combinations of steam and electricity sources, fuel used in each source, steam generation equipment and process details, and the extent of CO 2 capture. Comparing these scenarios reveals distinct trade-offs between thermal efficiency, net power output, levelized cost, profit, and net CO 2 reduction. Despite causing the highest loss in useful power output, bleeding steam and extracting electric power from the main power plant to meet the CCS plant's electricity and steam demand maximizes plant efficiency and profit while minimizing emissions and levelized cost when wholesale electricity prices are below 4.5 and 5.2 US¢/kWh for PC-CCS and NGCC-CCS plants, respectively. At prices higher than these higher profits for operating CCS retrofits can be obtained by meeting 100% of the CCS plant's electric power demand using an auxiliary natural gas turbine-based combined heat and power plant.

Anaerobic power and physical function in strength-trained and non-strength-trained older adults.

PubMed

Slade, Jill M; Miszko, Tanya A; Laity, Jennifer H; Agrawal, Subodoh K; Cress, M Elaine

2002-03-01

Challenging daily tasks, such as transferring heavy items or rising from the floor, may be dependent on the ability to generate short bursts of energy anaerobically. The purposes of this study were to determine if strength-trained (ST) older adults have higher anaerobic power output compared with non-strength-trained (NST) older adults and to determine the relationship between anaerobic power and performance-based physical function. Thirty-five men and women (age 71.5 +/- 6.4 years, mean +/- SD; NST: n = 18, ST: n = 17) were grouped by training status. Outcome variables included relative anaerobic power (Wingate test), physical function measured with the Continuous Scale Physical Functional Performance Test (CS-PFP, scaled 0 to 100), and anthropometric lean thigh volume (LTV). Analysis of covariance (with age and sex as covariates) was used to determine group differences in the dependent variables listed above. Pearson's r was used to determine the relationship between anaerobic power, CS-PFP total score (TOT), and CS-PFP lower body strength domain score (LBS). The ST group had significantly higher mean anaerobic power (NST 58.9 +/- 16 W/l, ST 96.3 +/- 23 W/l), CS-PFP total (NST 61.2 +/- 13, ST 73.7 +/- 8), and LBS (NST 54.1 +/- 17, ST 70.9 +/- 8) compared with the NST group (p <.05). However, LTV was similar for both groups (NST 3.323 +/- 0.75; ST 3.179 +/- 0.79), which suggests that the ST group had higher muscle quality compared with the NST group. Anaerobic power was significantly related to TOT (r =.611, p =.001) and LBS (r =.650, p =.001). High levels of physical function in ST older adults may in part be explained by higher levels of anaerobic power associated with strength training.

Leadership is associated with lower levels of stress

PubMed Central

Sherman, Gary D.; Lee, Jooa J.; Cuddy, Amy J. C.; Renshon, Jonathan; Oveis, Christopher; Gross, James J.; Lerner, Jennifer S.

2012-01-01

As leaders ascend to more powerful positions in their groups, they face ever-increasing demands. As a result, there is a common perception that leaders have higher stress levels than nonleaders. However, if leaders also experience a heightened sense of control—a psychological factor known to have powerful stress-buffering effects—leadership should be associated with reduced stress levels. Using unique samples of real leaders, including military officers and government officials, we found that, compared with nonleaders, leaders had lower levels of the stress hormone cortisol and lower reports of anxiety (study 1). In study 2, leaders holding more powerful positions exhibited lower cortisol levels and less anxiety than leaders holding less powerful positions, a relationship explained significantly by their greater sense of control. Altogether, these findings reveal a clear relationship between leadership and stress, with leadership level being inversely related to stress. PMID:23012416

A High-Power Wireless Charging System Development and Integration for a Toyota RAV4 Electric Vehicle

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

Onar, Omer C; Seiber, Larry Eugene; White, Cliff P

Several wireless charging methods are underdevelopment or available as an aftermarket option in the light-duty automotive market. However, there are not many studies detailing the vehicle integrations, particularly a complete vehicle integration with higher power levels. This paper presents the development, implementation, and vehicle integration of a high-power (>10 kW) wireless power transfer (WPT)-based electric vehicle (EV) charging system for a Toyota RAV4 vehicle. The power stages of the system are introduced with the design specifications and control systems including the active front-end rectifier with power factor correction (PFC), high frequency power inverter, high frequency isolation transformer, coupling coils, vehiclemore » side full-bridge rectifier and filter, and the vehicle battery. The operating principles of the control, communications, and protection systems are also presented in addition to the alignment and the driver interface system. The physical limitations of the system are also defined that would prevent the system operating at higher levels. The experiments are carried out using the integrated vehicle and the results obtained to demonstrate the system performance including the stage-by-stage efficiencies with matched and interoperable primary and secondary coils.« less

Variability in large-scale wind power generation: Variability in large-scale wind power generation

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

Kiviluoma, Juha; Holttinen, Hannele; Weir, David

2015-10-25

The paper demonstrates the characteristics of wind power variability and net load variability in multiple power systems based on real data from multiple years. Demonstrated characteristics include probability distribution for different ramp durations, seasonal and diurnal variability and low net load events. The comparison shows regions with low variability (Sweden, Spain and Germany), medium variability (Portugal, Ireland, Finland and Denmark) and regions with higher variability (Quebec, Bonneville Power Administration and Electric Reliability Council of Texas in North America; Gansu, Jilin and Liaoning in China; and Norway and offshore wind power in Denmark). For regions with low variability, the maximum 1more » h wind ramps are below 10% of nominal capacity, and for regions with high variability, they may be close to 30%. Wind power variability is mainly explained by the extent of geographical spread, but also higher capacity factor causes higher variability. It was also shown how wind power ramps are autocorrelated and dependent on the operating output level. When wind power was concentrated in smaller area, there were outliers with high changes in wind output, which were not present in large areas with well-dispersed wind power.« less

Feeling depleted and powerless: the construal-level mechanism.

PubMed

Kim, Junha; Lee, Sujin; Rua, Tuvana

2015-04-01

Individuals exercise self-control daily to achieve desired goals; at the same time, people engage in social interaction daily and influence (feel powerful) or are influenced (feel powerless) by others. Does controlling the self have an unforeseen consequence for people's perception of their capacity to control others? Five studies-one correlational and four experimental-demonstrate that ego depletion from prior self-control determines one's personal sense of power; low-level, concrete mental construals account for this relationship. Our results showed that people with higher trait self-control reported a greater sense of power (Study 1). People who had depleted their self-control-related regulatory resources (vs. those who had not) experienced a lower sense of power (Study 2). The relationship between ego depletion and low sense of power was mediated by construal level (Study 3) and observed only when low-level, concrete construals were present, but not under high-level, abstract construals (Studies 4 and 5). © 2015 by the Society for Personality and Social Psychology, Inc.

How Do Health Insurer Market Concentration and Bargaining Power with Hospitals Affect Health Insurance Premiums?

PubMed Central

Trish, Erin E.; Herring, Bradley J.

2017-01-01

The US health insurance industry is highly concentrated, and health insurance premiums are high and rising rapidly. Policymakers have focused on the possible link between the two, leading to ACA provisions to increase insurer competition. However, while market power may enable insurers to include higher profit margins in their premiums, it may also result in stronger bargaining leverage with hospitals to negotiate lower payment rates to partially offset these higher premiums. We empirically examine the relationship between employer-sponsored fully-insured health insurance premiums and the level of concentration in local insurer and hospital markets using the nationally-representative 2006–2011 KFF/HRET Employer Health Benefits Survey. We exploit a unique feature of employer-sponsored insurance, in which self-insured employers purchase only administrative services from managed care organizations, to disentangle these different effects on insurer concentration by constructing one concentration measure representing fully-insured plans’ transactions with employers and the other concentration measure representing insurers’ bargaining with hospitals. As expected, we find that premiums are indeed higher for plans sold in markets with higher levels of concentration relevant to insurer transactions with employers, lower for plans in markets with higher levels of insurer concentration relevant to insurer bargaining with hospitals, and higher for plans in markets with higher levels of hospital market concentration. PMID:25910690

How do health insurer market concentration and bargaining power with hospitals affect health insurance premiums?

PubMed

Trish, Erin E; Herring, Bradley J

2015-07-01

The US health insurance industry is highly concentrated, and health insurance premiums are high and rising rapidly. Policymakers have focused on the possible link between the two, leading to ACA provisions to increase insurer competition. However, while market power may enable insurers to include higher profit margins in their premiums, it may also result in stronger bargaining leverage with hospitals to negotiate lower payment rates to partially offset these higher premiums. We empirically examine the relationship between employer-sponsored fully-insured health insurance premiums and the level of concentration in local insurer and hospital markets using the nationally-representative 2006-2011 KFF/HRET Employer Health Benefits Survey. We exploit a unique feature of employer-sponsored insurance, in which self-insured employers purchase only administrative services from managed care organizations, to disentangle these different effects on insurer concentration by constructing one concentration measure representing fully-insured plans' transactions with employers and the other concentration measure representing insurers' bargaining with hospitals. As expected, we find that premiums are indeed higher for plans sold in markets with higher levels of concentration relevant to insurer transactions with employers, lower for plans in markets with higher levels of insurer concentration relevant to insurer bargaining with hospitals, and higher for plans in markets with higher levels of hospital market concentration. Copyright © 2015 Elsevier B.V. All rights reserved.

Active Power Control of Waked Wind Farms: Preprint

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

Fleming, Paul A; van Wingerden, Jan-Willem; Pao, Lucy

Active power control can be used to balance the total power generated by wind farms with the power consumed on the electricity grid. With the increasing penetration levels of wind energy, there is an increasing need for this ancillary service. In this paper, we show that the tracking of a certain power reference signal provided by the transmission system operator can be significantly improved by using feedback control at the wind farm level. We propose a simple feedback control law that significantly improves the tracking behavior of the total power output of the farm, resulting in higher performance scores. Themore » effectiveness of the proposed feedback controller is demonstrated using high-fidelity computational fluid dynamics simulations of a small wind farm.« less

Low Energy Dissipation Nano Device Research

NASA Astrophysics Data System (ADS)

Yu, Jenny

2015-03-01

The development of research on energy dissipation has been rapid in energy efficient area. Nano-material power FET is operated as an RF power amplifier, the transport is ballistic, noise is limited and power dissipation is minimized. The goal is Green-save energy by developing the Graphene and carbon nantube microwave and high performance devices. Higher performing RF amplifiers can have multiple impacts on broadly field, for example communication equipment, (such as mobile phone and RADAR); higher power density and lower power dissipation will improve spectral efficiency which translates into higher system level bandwidth and capacity for communications equipment. Thus, fundamental studies of power handling capabilities of new RF (nano)technologies can have broad, sweeping impact. Because it is critical to maximizing the power handling ability of grephene and carbon nanotube FET, the initial task focuses on measuring and understanding the mechanism of electrical breakdown. We aim specifically to determine how the breakdown voltage in graphene and nanotubes is related to the source-drain spacing, electrode material and thickness, and substrate, and thus develop reliable statistics on the breakdown mechanism and probability.

Exposure to ultrafine particles and black carbon in diesel-powered commuter trains

NASA Astrophysics Data System (ADS)

Jeong, Cheol-Heon; Traub, Alison; Evans, Greg J.

2017-04-01

Ultrafine particle (UFP), black carbon (BC) and lung deposited surface area (LDSA) concentrations measured during 43 trips on diesel-powered commuter trains revealed elevated exposures under some conditions. When the passenger coaches were pulled by a locomotive, the geometric mean concentrations of UFP, LDSA, and BC were 18, 10, and 6 times higher than the exposure levels when the locomotive pushed the coaches, respectively. In addition, UFP, LDSA, and BC concentrations in pull-trains were 5, 3, and 4 times higher than concentrations measured while walking on city sidewalks, respectively. Exposure to these pollutants was most elevated in the coach located closest to the locomotive: geometric means were 126,000 # cm-3 for UFP, 249 μm2 cm-3 for LDSA, and 17,800 ng m-3 of BC; these concentrations are much higher than those previously reported for other modes of public transportation. Markedly high levels of diesel exhaust are present in passenger trains powered by diesel locomotives operated in pull-mode. Thus, it is recommended that immediate steps be taken to evaluate, and where needed, mitigate exposure in diesel-powered passenger trains, both commuter and inter-city.

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

Rosenkranz, Joshua-Benedict; Brancucci Martinez-Anido, Carlo; Hodge, Bri-Mathias

Solar power generation, unlike conventional forms of electricity generation, has higher variability and uncertainty in its output because solar plant output is strongly impacted by weather. As the penetration rate of solar capacity increases, grid operators are increasingly concerned about accommodating the increased variability and uncertainty that solar power provides. This paper illustrates the impacts of increasing solar power penetration on the ramping of conventional electricity generators by simulating the operation of the Independent System Operator -- New England power system. A production cost model was used to simulate the power system under five different scenarios, one without solar powermore » and four with increasing solar power penetrations up to 18%, in terms of annual energy. The impact of solar power is analyzed on six different temporal intervals, including hourly and multi-hourly (2- to 6-hour) ramping. The results show how the integration of solar power increases the 1- to 6-hour ramping events of the net load (electric load minus solar power). The study also analyzes the impact of solar power on the distribution of multi-hourly ramping events of fossil-fueled generators and shows increasing 1- to 6-hour ramping events for all different generators. Generators with higher ramp rates such as gas and oil turbine and internal combustion engine generators increased their ramping events by 200% to 280%. For other generator types--including gas combined-cycle generators, coal steam turbine generators, and gas and oil steam turbine generators--more and higher ramping events occurred as well for higher solar power penetration levels.« less

Higher Levels of Intrinsic Motivation Are Related to Higher Levels of Class Performance for Male but Not Female Students

ERIC Educational Resources Information Center

Cortright, Ronald N.; Lujan, Heidi L.; Blumberg, Amanda J.; Cox, Julie H.; DiCarlo, Stephen E.

2013-01-01

Our students are naturally curious, with powerful intrinsic motives to understand their world. Accordingly, we, as teachers, must capitalize on this inherently active and curious nature so that learning becomes a lifelong activity where students take initiative for learning, are skilled in learning, and want to learn new things. Achieving this…

Characterization of zero-bias microwave diode power detectors at cryogenic temperature.

PubMed

Giordano, Vincent; Fluhr, Christophe; Dubois, Benoît; Rubiola, Enrico

2016-08-01

We present the characterization of commercial tunnel diode low-level microwave power detectors at room and cryogenic temperatures. The sensitivity as well as the output voltage noise of the tunnel diodes is measured as functions of the applied microwave power. We highlight strong variations of the diode characteristics when the applied microwave power is higher than a few microwatts. For a diode operating at 4 K, the differential gain increases from 1000 V/W to about 4500 V/W when the power passes from -30 dBm to -20 dBm. The diode white noise floor is equivalent to a Noise Equivalent Power of 0.8 pW/Hz and 8 pW/Hz at 4 K and 300 K, respectively. Its flicker noise is equivalent to a relative amplitude noise power spectral density Sα(1 Hz) = - 120 dB/Hz at 4 K. Flicker noise is 10 dB higher at room temperature.

Temperature Effects in Varactors and Multipliers

NASA Technical Reports Server (NTRS)

East, J.; Mehdi, Imran

2001-01-01

Varactor diode multipliers are a critical part of many THz measurement systems. The power and efficiencies of these devices limit the available power for THz sources. Varactor operation is determined by the physics of the varactor device and a careful doping profile design is needed to optimize the performance. Higher doped devices are limited by junction breakdown and lower doped structures are limited by current saturation. Higher doped structures typically have higher efficiencies and lower doped structures typically have higher powers at the same operating frequency and impedance level. However, the device material properties are also a function of the operating temperature. Recent experimental evidence has shown that the power output of a multiplier can be improved by cooling the device. We have used a particle Monte Carlo simulation to investigate the temperature dependent velocity vs. electric field in GaAs. This information was then included in a nonlinear device circuit simulator to predict multiplier performance for various temperatures and device designs. This paper will describe the results of this analysis of temperature dependent multiplier operation.

Determinants of mobile phone output power in a multinational study: implications for exposure assessment.

PubMed

Vrijheid, M; Mann, S; Vecchia, P; Wiart, J; Taki, M; Ardoino, L; Armstrong, B K; Auvinen, A; Bédard, D; Berg-Beckhoff, G; Brown, J; Chetrit, A; Collatz-Christensen, H; Combalot, E; Cook, A; Deltour, I; Feychting, M; Giles, G G; Hepworth, S J; Hours, M; Iavarone, I; Johansen, C; Krewski, D; Kurttio, P; Lagorio, S; Lönn, S; McBride, M; Montestrucq, L; Parslow, R C; Sadetzki, S; Schüz, J; Tynes, T; Woodward, A; Cardis, E

2009-10-01

The output power of a mobile phone is directly related to its radiofrequency (RF) electromagnetic field strength, and may theoretically vary substantially in different networks and phone use circumstances due to power control technologies. To improve indices of RF exposure for epidemiological studies, we assessed determinants of mobile phone output power in a multinational study. More than 500 volunteers in 12 countries used Global System for Mobile communications software-modified phones (GSM SMPs) for approximately 1 month each. The SMPs recorded date, time, and duration of each call, and the frequency band and output power at fixed sampling intervals throughout each call. Questionnaires provided information on the typical circumstances of an individual's phone use. Linear regression models were used to analyse the influence of possible explanatory variables on the average output power and the percentage call time at maximum power for each call. Measurements of over 60,000 phone calls showed that the average output power was approximately 50% of the maximum, and that output power varied by a factor of up to 2 to 3 between study centres and network operators. Maximum power was used during a considerable proportion of call time (39% on average). Output power decreased with increasing call duration, but showed little variation in relation to reported frequency of use while in a moving vehicle or inside buildings. Higher output powers for rural compared with urban use of the SMP were observed principally in Sweden where the study covered very sparsely populated areas. Average power levels are substantially higher than the minimum levels theoretically achievable in GSM networks. Exposure indices could be improved by accounting for average power levels of different telecommunications systems. There appears to be little value in gathering information on circumstances of phone use other than use in very sparsely populated regions.

Multimode Directional Coupler for Utilization of Harmonic Frequencies from TWTAs

NASA Technical Reports Server (NTRS)

Simmons, Rainee N.; Wintucky, Edwin G.

2013-01-01

A novel waveguide multimode directional coupler (MDC) intended for the measurement and potential utilization of the second and higher order harmonic frequencies from high-power traveling wave tube amplifiers (TWTAs) has been successfully designed, fabricated, and tested. The design is based on the characteristic multiple propagation modes of the electrical and magnetic field components of electromagnetic waves in a rectangular waveguide. The purpose was to create a rugged, easily constructed, more efficient waveguide- based MDC for extraction and exploitation of the second harmonic signal from the RF output of high-power TWTs used for space communications. The application would be a satellitebased beacon source needed for Qband and V/W-band atmospheric propagation studies. The MDC could function as a CW narrow-band source or as a wideband source for study of atmospheric group delay effects on highdata- rate links. The MDC is fabricated from two sections of waveguide - a primary one for the fundamental frequency and a secondary waveguide for the second harmonic - that are joined together such that the second harmonic higher order modes are selectively coupled via precision- machined slots for propagation in the secondary waveguide. In the TWTA output waveguide port, both the fundamental and the second harmonic signals are present. These signals propagate in the output waveguide as the dominant and higher order modes, respectively. By including an appropriate mode selective waveguide directional coupler, such as the MDC presented here at the output of the TWTA, the power at the second harmonic can be sampled and amplified to the power level needed for atmospheric propagation studies. The important conclusions from the preliminary test results for the multimode directional coupler are: (1) the second harmonic (Ka-band) can be measured and effectively separated from the fundamental (Ku-band) with no coupling of the latter, (2) power losses in the fundamental frequency are negligible, and (3) the power level of the extracted second harmonic is sufficient for further amplification to power levels needed for practical applications. It was also demonstrated that third order and potentially higher order harmonics are measurable with this device. The design is frequency agnostic, and with the appropriate choice of waveguides, is easily scaled to higher frequency TWTs. The MDC has the same function but with a number of important advantages over the conventional diplexer.

Concerns and perceptions immediately following Superstorm Sandy: ratings for property damage were higher than for health issues

PubMed Central

Burger, Joanna; Gochfeld, Michael

2015-01-01

Governmental officials, health and safety professionals, early responders, and the public are interested in the perceptions and concerns of people faced with a crisis, especially during and immediately after a disaster strikes. Reliable information can lead to increased individual and community preparedness for upcoming crises. The objective of this research was to evaluate concerns of coastal and central New Jersey residents within the first 100 days of Superstorm Sandy’s landfall. Respondents living in central New Jersey and Jersey shore communities were differentially impacted by the storm, with shore residents having higher evacuation rates (47% vs. 13%), more flood waters in their homes, longer power outages (average 23 vs. 6 days), and longer periods without Internet (29 vs. 6 days). Ratings of concerns varied both among and within categories as a function of location (central vs. coastal New Jersey), stressor level (ranging from 1 to 3 for combinations of power outages, high winds, and flooding), and demographics. Respondents were most concerned about property damage, health, inconveniences, ecological services, and nuclear power plants in that order. Respondents from the shore gave higher ratings to the concerns within each major category, compared to those from central Jersey. Four findings have implications for understanding future risk, recovery, and resiliency: (1) respondents with the highest stressor level (level 3) were more concerned about water damage than others, (2) respondents with flood damage were more concerned about water drainage and mold than others, (3) respondents with the highest stressor levels rated all ecological services higher than others, and (4) shore respondents rated all ecological services higher than central Jersey residents. These data provide information to design future preparedness plans, improve resiliency for future severe weather events, and reduce public health risk. PMID:27011757

50W CW output power and 12mJ pulses from a quasi-2-level Yb:YAG ceramic rod laser end-pumped at the 969nm zero-phonon line

NASA Astrophysics Data System (ADS)

Fries, Christian; Weitz, Marco; Theobald, Christian; v. Löwis of Menar, Patric; Bartschke, Jürgen; L'huillier, Johannes A.

2015-02-01

With the advent of high power and narrow bandwidth 969 nm pump diodes, direct pumping into the upper laser level of Yb:YAG and hence quasi-2-level lasers became possible. Pumping directly into the emitting level leads to higher quantum efficiency and reduction of non-radiative decay. Consequently, thermal load, thermal lensing and risk of fracture are reduced significantly. Moreover pump saturation and thermal population of uninvolved energy-levels in ground and excited states are benefical for a homogenous distribution of the pump beam as well as the reduction of reabsorption loss compared to 3-level systems, which allows for high-power DPSS lasers. Beside continuous-wave (cw) operation, nanosecond pulses with a repetition rate between 1 and 5 kHz are an attractive alternative to flashlamp-pumped systems (10-100 Hz) in various measurement applications that require higher data acquisition rates because of new faster detectors. Based on measurements of the absorption and a detailed numerical model for pump beam distribution, including beam propagation and saturation factors, power-scaling of a ceramic rod Yb:YAG oscillator was possible. Finally a cw output power of 50 W with 33 % pump efficiency at 1030 nm has been demonstrated (M2 < 1.2). Nanosecond pulses have been produced by cavity-dumping of this system. The cavity-dumped setup allowed for 3-10 ns pulses with a pulse energy of 12.5 mJ at 1 kHz (M2 < 1.1). In order to achieve these results a systematic experimental and numerical investigation on gain dynamics and the identification of different stable operating regimes has been carried out.

Switch wear leveling

DOEpatents

Wu, Hunter; Sealy, Kylee; Gilchrist, Aaron

2015-09-01

An apparatus for switch wear leveling includes a switching module that controls switching for two or more pairs of switches in a switching power converter. The switching module controls switches based on a duty cycle control technique and closes and opens each switch in a switching sequence. The pairs of switches connect to a positive and negative terminal of a DC voltage source. For a first switching sequence a first switch of a pair of switches has a higher switching power loss than a second switch of the pair of switches. The apparatus includes a switch rotation module that changes the switching sequence of the two or more pairs of switches from the first switching sequence to a second switching sequence. The second switch of a pair of switches has a higher switching power loss than the first switch of the pair of switches during the second switching sequence.

ACTN3 R577X Gene Variant Is Associated With Muscle-Related Phenotypes in Elite Chinese Sprint/Power Athletes.

PubMed

Yang, Ruoyu; Shen, Xunzhang; Wang, Yubin; Voisin, Sarah; Cai, Guang; Fu, Yongnan; Xu, Wangyu; Eynon, Nir; Bishop, David J; Yan, Xu

2017-04-01

Yang, R, Shen, X, Wang, Y, Voisin, S, Cai, G, Fu, Y, Xu, W, Eynon, N, Bishop, DJ, and Yan, X. ACTN3 R577X gene variant is associated with muscle-related phenotypes in elite Chinese sprint/power athletes. J Strength Cond Res 31(4): 1107-1115, 2017-The ACTN3 R577X polymorphism (rs1815739) has been shown to influence athletic performance. The aim of this study was to investigate the prevalence of this polymorphism in elite Chinese track and field athletes, and to explore its effects on athletes' level of competition and lower-extremity power. We compared the ACTN3 R577X genotypes and allele frequencies in 59 elite sprint/power athletes, 44 elite endurance athletes, and 50 healthy controls from Chinese Han origin. We then subcategorized the athletes into international level and national level and investigated the effects of ACTN3 genotype on lower-extremity power. Genotype distribution of the sprint/power athletes was significantly different from endurance athletes (p = 0.001) and controls (p < 0.001). The frequency of the RR genotype was significantly higher in international-level than that in the national-level sprint/power athletes (p = 0.004), with no international-level sprint/power athletes with XX genotype. The best standing long jump and standing vertical jump results of sprint/power athletes were better in the RR than those in the RX + XX genotypes (p = 0.004 and p = 0.001, respectively). In conclusion, the ACTN3 R577X polymorphism influences the level of competition and lower-extremity power of elite Chinese sprint/power athletes. Including relevant phenotypes such as muscle performance in future studies is important to further understand the effects of gene variants on elite athletic performance.

Effects of processing parameters on the inactivation of Bacillus cereus spores on red pepper (Capsicum annum L.) flakes by microwave-combined cold plasma treatment.

PubMed

Kim, Jung Eun; Choi, Hyeon-Son; Lee, Dong-Un; Min, Sea C

2017-12-18

The efficacy of microwave-combined cold plasma treatment (MCPT) for inactivating Bacillus cereus spores contaminating red pepper (Capsicum annum L.) flakes was investigated. The effects of red pepper drying method, particle size, and water activity (a w ) were also evaluated at two levels of microwave power (1700 and 2500W/cm 2 ). The inactivation effect of MCPT was higher at higher microwave power. Spore reduction was more effective with vacuum-dried red pepper than far-infrared-dried flakes. A significantly higher level of spore reduction was observed with the red pepper sample with a smaller surface to volume ratio when one surface (exterior surface) was inoculated (p<0.05). Spore reduction by MCPT at high microwave power increased from 1.7 to 2.6logspores/cm 2 when the a w of flake increased from 0.4 to 0.9 (p<0.05). MCPT did not change the color of red pepper flakes. MCPT demonstrated potential as a microbial decontaminating technology for red pepper flakes. Copyright © 2017 Elsevier B.V. All rights reserved.

The SCARLET{trademark} array for high power GEO satellites

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

Spence, B.R.; Jones, P.A.; Eskenazi, M.I.

1997-12-31

The GEO satellite market is demanding increasingly capable spacecraft which, in turn, drives commercial spacecraft manufacturers to require significantly higher power solar arrays. As satellite capability increases the demand for high power array systems which are both cost and performance competitive becomes more crucial. Conventional rigid panel planar arrays, although suitable in the past, negatively impact spacecraft competitiveness for these new applications. The Solar Concentrator Array with Refractive Linear Element Technology (SCARLET{trademark}) represents an economically attractive solution for meeting these new high power requirements. When compared to conventional planar arrays, SCARLET provides substantially lower cost and higher deployed stiffness, competitivemore » mass, better producibility, and affordable use of high efficiency multijunction cells. This paper compares cost/performance characteristics of the SCARLET array to conventional planar arrays for high power GEO spacecraft applications. High power SCARLET array configurations are described, and inherent spacecraft and array level cost/performance benefits are presented.« less

Design of investment management optimization system for power grid companies under new electricity reform

NASA Astrophysics Data System (ADS)

Yang, Chunhui; Su, Zhixiong; Wang, Xin; Liu, Yang; Qi, Yongwei

2017-03-01

The new normalization of the economic situation and the implementation of a new round of electric power system reform put forward higher requirements to the daily operation of power grid companies. As an important day-to-day operation of power grid companies, investment management is directly related to the promotion of the company's operating efficiency and management level. In this context, the establishment of power grid company investment management optimization system will help to improve the level of investment management and control the company, which is of great significance for power gird companies to adapt to market environment changing as soon as possible and meet the policy environment requirements. Therefore, the purpose of this paper is to construct the investment management optimization system of power grid companies, which includes investment management system, investment process control system, investment structure optimization system, and investment project evaluation system and investment management information platform support system.

Polarization-maintaining performance of large effective area, higher order modes fiber in a coiled configuration

NASA Astrophysics Data System (ADS)

Ahmad, Raja; Nicholson, Jeffrey W.; Abedin, Kazi S.; Westbrook, Paul S.; Headley, Clifford; Wisk, Patrick W.; Monberg, Eric M.; Yan, Man F.; DiGiovanni, David J.

2018-02-01

Scaling the power-level of fiber sources has many practical advantages, while also enabling fundamental studies on the light-matter interaction in amorphous guiding media. In order to scale the power-level of fiber-sources without encountering nonlinear impairments, a strategy is to increase the effective-area of the guided optical-mode. Increasing the effective-area of the fundamental mode in a fiber, however, presents the challenges of increased susceptibility to mode-distortion and effective-area-reduction under the influence of bends. Therefore, higher-order-mode (HOM) fibers, which guide light in large effective-area (Aeff) Bessel-like modes, are a good candidate for scaling the power-level of robust fiber-sources. Many applications of high-power fiber-sources also demand a deterministic control on the polarization-state of light. Furthermore, a polarization-maintaining (PM)-type HOM fiber can afford the added possibility of coherent-beam combination and polarization multiplexing of high-power fiber-lasers. Previously, we reported polarization-maintaining operation in a 1.3 m length of PM-HOM fiber that was held straight. The PM-HOM fiber guided Bessel-like modes with Aeff ranging from 1200-2800 μm2. In this work, we report, for the first time, that the polarization-extinction-ratio (PER) of the HOM exceeds 10 dB in an 8 m long fiber that is coiled down to a diameter of 40 cm. This opens a path towards compact and polarization-controlled high-power fiber-systems.

Off-Design Performance Analysis of a Solid-Oxide Fuel Cell/Gas Turbine Hybrid for Auxiliary Aerospace Power

NASA Technical Reports Server (NTRS)

Freeh, Joshua E.; Steffen, J., Jr.; Larosiliere, Louis M.

2005-01-01

A solid-oxide fuel cell/gas turbine hybrid system for auxiliary aerospace power is analyzed using 0-D and 1-D system-level models. The system is designed to produce 440 kW of net electrical power, sized for a typical long-range 300-passenger civil airplane, at both sea level and cruise flight level (12,500 m). In addition, a part power level of 250 kW is analyzed at the cruise condition, a requirement of the operating power profile. The challenge of creating a balanced system for the three distinct conditions is presented, along with the compromises necessary for each case. A parametric analysis is described for the cruise part power operating point, in which the system efficiency is maximized by varying the air flow rate. The system is compared to an earlier version that was designed solely for cruise operation. The results show that it is necessary to size the turbomachinery, fuel cell, and heat exchangers at sea level full power rather than cruise full power. The resulting estimated mass of the system is 1912 kg, which is significantly higher than the original cruise design point mass, 1396 kg. The net thermal efficiencies with respect to the fuel LHV are calculated to be 42.4 percent at sea level full power, 72.6 percent at cruise full power, and 72.8 percent at cruise part power. The cruise conditions take advantage of pre-compressed air from the on-board Environmental Control System, which accounts for a portion of the unusually high thermal efficiency at those conditions. These results show that it is necessary to include several operating points in the overall assessment of an aircraft power system due to the variations throughout the operating profile.

Long-Term Consequences of Curriculum Choices with Particular Reference to Mathematics and Science.

ERIC Educational Resources Information Center

Fitz-Gibbon, Carol Taylor

1999-01-01

Explores consequences of taking or not taking "A" level mathematics in British secondary schools, using a followup study of students who took "A" levels in 1988. "A" level mathematics takers were in high "pulling power" universities and had higher salary expectations than those taking "A" level…

Differential effects of power rehabilitation on physical performance and higher-level functional capacity among community-dwelling older adults with a slight degree of frailty.

PubMed

Ota, Atsuhiko; Yasuda, Nobufumi; Horikawa, Shunichi; Fujimura, Takashi; Ohara, Hiroshi

2007-03-01

Evidence is still insufficient regarding the effects of Power Rehabilitation (PR) on physical performance and higher-level functional capacity of community-dwelling frail elderly people. This nonrandomized controlled interventional trial consisted of 46 community-dwelling elderly individuals with light levels of long-term care needs. They were allocated to the intervention (I-group, n = 24) and control (C-group, n = 22) groups. Of them, 32 persons (17 in the I-group; 15 in the C-group) (median age, 77 years; sex, 28% male) completed the study. The I-group subjects underwent PR twice a week for 12 weeks. The outcomes were physical performance (muscle strength, balance, flexibility, and mobility) and higher-level functional capacity as evaluated by the Tokyo Metropolitan Institute of Gerontology Index of Competence (TMIG-IC) and the level of long-term care need as certified by the public long-term care insurance. The I-group demonstrated a significant improvement in the measured value of the timed up-and-go test (median change, a decrease of 4.4 seconds versus a decrease of 0.2 seconds, p = 0.033) and the timed 10-meter walk (a decrease of 3.0 seconds versus an increase of 0.2 seconds, p = 0.007) in comparison with the C-group. No significant change was observed in the TMIG-IC scores or in the level of long-term care need in the I-group. PR improved mobility of community-dwelling frail elderly people; however, such improvement did not translate into higher-level functional capacity. Our findings demonstrate the difficulty in transferring the positive effects associated with PR into an improvement in higher-level functional capacity.

Ultra-low-power and robust digital-signal-processing hardware for implantable neural interface microsystems.

PubMed

Narasimhan, S; Chiel, H J; Bhunia, S

2011-04-01

Implantable microsystems for monitoring or manipulating brain activity typically require on-chip real-time processing of multichannel neural data using ultra low-power, miniaturized electronics. In this paper, we propose an integrated-circuit/architecture-level hardware design framework for neural signal processing that exploits the nature of the signal-processing algorithm. First, we consider different power reduction techniques and compare the energy efficiency between the ultra-low frequency subthreshold and conventional superthreshold design. We show that the superthreshold design operating at a much higher frequency can achieve comparable energy dissipation by taking advantage of extensive power gating. It also provides significantly higher robustness of operation and yield under large process variations. Next, we propose an architecture level preferential design approach for further energy reduction by isolating the critical computation blocks (with respect to the quality of the output signal) and assigning them higher delay margins compared to the noncritical ones. Possible delay failures under parameter variations are confined to the noncritical components, allowing graceful degradation in quality under voltage scaling. Simulation results using prerecorded neural data from the sea-slug (Aplysia californica) show that the application of the proposed design approach can lead to significant improvement in total energy, without compromising the output signal quality under process variations, compared to conventional design approaches.

Nurse executive transformational leadership found in participative organizations.

PubMed

Dunham-Taylor, J

2000-05-01

The study examined a national sample of 396 randomly selected hospital nurse executives to explore transformational leadership, stage of power, and organizational climate. Results from a few nurse executive studies have found nurse executives were transformational leaders. As executives were more transformational, they achieved better staff satisfaction and higher work group effectiveness. This study integrates Bass' transformational leadership model with Hagberg's power stage theory and Likert's organizational climate theory. Nurse executives (396) and staff reporting to them (1,115) rated the nurse executives' leadership style, staff extra effort, staff satisfaction, and work group effectiveness using Bass and Avolio's Multifactor Leadership Questionnaire. Executives' bosses (360) rated executive work group effectiveness. Executives completed Hagberg's Personal Power Profile and ranked their organizational climate using Likert's Profile of Organizational Characteristics. Nurse executives used transformational leadership fairly often; achieved fairly satisfied staff levels; were very effective according to bosses; were most likely at stage 3 (power by achievement) or stage 4 (power by reflection); and rated their hospital as a Likert System 3 Consultative Organization. Staff satisfaction and work group effectiveness decreased as nurse executives were more transactional. Higher transformational scores tended to occur with higher educational degrees and within more participative organizations. Transformational qualities can be enhanced by further education, by achieving higher power stages, and by being within more participative organizations.

Relationship Factors and Trajectories of Intimate Partner Violence among South African Women during Pregnancy and the Postpartum Period

PubMed Central

Groves, Allison K.; McNaughton-Reyes, H. Luz; Foshee, Vangie A.; Moodley, Dhayendre; Maman, Suzanne

2014-01-01

Intimate partner violence (IPV) is a significant public health problem in South Africa. However, there is limited research on whether and how IPV changes during pregnancy and the postpartum period and on the factors that might affect women's risk during this time. In this study, we describe the mean trajectories of physical and psychological IPV during pregnancy and the postpartum period and examine whether relationship power, partner social support, and relationship stress are associated with women's trajectories of IPV. Data come from a longitudinal study with 1,480 women recruited during pregnancy between May 2008 and June 2010 at a public clinic in Durban. Women completed behavioral assessments at their first antenatal visit, at fourteen weeks and at nine months postpartum. Women's experiences of IPV were measured at all three time points and relationship power, partner social support and relationship stress were each measured at the baseline assessment. We used multilevel random coefficients growth modeling to build our models. The mean trajectory for both types of IPV was flat which means that, on average, there was not significant change in levels of IPV over pregnancy and the postpartum period. However, there was significant individual variability in trajectories of IPV over the study period. Women who had higher relationship power had lower levels of physical and psychological IPV over time than women with lower relationship power. Additionally, women with higher relationship stress and lower partner support had higher levels of psychological IPV at pregnancy. Interventions that maximize women's relationship power and partner social support and minimize relationship stress during this transformative time are needed. PMID:25268363

Wind power generation and dispatch in competitive power markets

NASA Astrophysics Data System (ADS)

Abreu, Lisias

Wind energy is currently the fastest growing type of renewable energy. The main motivation is led by more strict emission constraints and higher fuel prices. In addition, recent developments in wind turbine technology and financial incentives have made wind energy technically and economically viable almost anywhere. In restructured power systems, reliable and economical operation of power systems are the two main objectives for the ISO. The ability to control the output of wind turbines is limited and the capacity of a wind farm changes according to wind speeds. Since this type of generation has no production costs, all production is taken by the system. Although, insufficient operational planning of power systems considering wind generation could result in higher system operation costs and off-peak transmission congestions. In addition, a GENCO can participate in short-term power markets in restructured power systems. The goal of a GENCO is to sell energy in such a way that would maximize its profitability. However, due to market price fluctuations and wind forecasting errors, it is essential for the wind GENCO to keep its financial risk at an acceptable level when constituting market bidding strategies. This dissertation discusses assumptions, functions, and methodologies that optimize short-term operations of power systems considering wind energy, and that optimize bidding strategies for wind producers in short-term markets. This dissertation also discusses uncertainties associated with electricity market environment and wind power forecasting that can expose market participants to a significant risk level when managing the tradeoff between profitability and risk.

Opportunity or Exploitation? Women and Quality Assurance in Higher Education

ERIC Educational Resources Information Center

Morley, Louise

2005-01-01

Based on interviews with 18 UK women academics and managers on quality and power in higher education, this article interrogates the impact of quality assurance discourses and practices on women in higher education. Micro-level analysis of the effects of audit and the evaluative state seem to suggest that hegemonic masculinities and gendered power…

Pulsed Magnetic Field Driven Gas Core Reactors for Space Power & Propulsion Applications

NASA Technical Reports Server (NTRS)

Anghaie, Samim; Smith, Blair; Knight, Travis; Butler, Carey

2003-01-01

The present results indicated that: 1. A pulsed magnetic driven fission power concept, PMD-GCR is developed for closed (NER) and semi-open (NTR) operations. 2. In power mode, power is generated at alpha less than 1 for power levels of hundreds of KW or higher 3. IN semi open NTR mode, PMD-GCR generates thrust at I(sub sp) approx. 5,000 s and jet power approx. 5KW/Kg. 4. PMD-GCR is highly subcritical and is actively driven to critically. 5. Parallel path with fusion R&D needs in many areas including magnet and plasma.

Power Exercise in the Institutionalization of an eProcurement System in Indonesian Local Government

NASA Astrophysics Data System (ADS)

Wahid, Fathul

2017-03-01

Power possessed by institutional entrepreneur is believed to have an influential role in navigating the institutionalization process of an idea. However, only few studies that have examined how the institutional entrepreneur exercise his power throughout the institutionalization process. This study aims at examining this phenomenon in the context of developing countries with special reference to the implementation of an eProcurement system in Indonesia. It finds that the power has been exercised by the institutional entrepreneur differently along the process. Smart power was exercised by combining soft power at the early stage of institutionalization process. At this stage level of reluctance among organizational members was high, no authorization from higher-level agencies, and the benefits of adopting the system were opaque. Hard power was then exercised at the later stage, when the legal support was well formulated, and the system’s benefits were confirmed. The study also reveals that value-based power that is used wisely make organization change runs smoothly until it becomes institutionalized. Keywords: Institutionalization, smart power, soft power, hard power, value-guided power, eGovernment, eProcurement, Indonesia, developing countries.

Challenges of Engineering Higher Education in a Transitional Economy: A Russian Experience

ERIC Educational Resources Information Center

Matveev, Alexei; Matveev, Olga; Zhukov, Vassily

2005-01-01

Education and training serve as critical elements of advancement of a nation's economy in transition. The restructuring of the power engineering industry in Russia has called for a fast implementation of new management system in electric power engineering and radical training of professional managers at different levels in organizations.…

Inventing an Energy Internet: Concepts, Architectures and Protocols for Smart Energy Utilization

ScienceCinema

Tsoukalas, Lefteri

2018-01-24

In recent years, the Internet is revolutionizing information availability much like the Power Grid revolutionized energy availability a century earlier. We will explore the differences and similarities of these two critical infrastructures and identify ways for convergence which may lead to an energy internet. Pricing signals, nodal forecasting, and short-term elasticities are key concepts in smart energy flows respecting the delicate equilibrium involved in generation-demand and aiming at higher efficiencies. We will discuss how intelligent forecasting approaches operating at multiple levels (including device or nodal levels) can ameliorate the challenges of power storage. In addition to higher efficiencies, an energy internet may achieve significant reliability and security improvements and offer greater flexibility and transparency in the overall energy-environmental relation.

Conceptual study of superconducting urban area power systems

NASA Astrophysics Data System (ADS)

Noe, Mathias; Bach, Robert; Prusseit, Werner; Willén, Dag; Gold-acker, Wilfried; Poelchau, Juri; Linke, Christian

2010-06-01

Efficient transmission, distribution and usage of electricity are fundamental requirements for providing citizens, societies and economies with essential energy resources. It will be a major future challenge to integrate more sustainable generation resources, to meet growing electricity demand and to renew electricity networks. Research and development on superconducting equipment and components have an important role to play in addressing these challenges. Up to now, most studies on superconducting applications in power systems have been concentrated on the application of specific devices like for example cables and current limiters. In contrast to this, the main focus of our study is to show the consequence of a large scale integration of superconducting power equipment in distribution level urban power systems. Specific objectives are to summarize the state-of-the-art of superconducting power equipment including cooling systems and to compare the superconducting power system with respect to energy and economic efficiency with conventional solutions. Several scenarios were considered starting from the replacement of an existing distribution level sub-grid up to a full superconducting urban area distribution level power system. One major result is that a full superconducting urban area distribution level power system could be cost competitive with existing solutions in the future. In addition to that, superconducting power systems offer higher energy efficiency as well as a number of technical advantages like lower voltage drops and improved stability.

Efficiency of different methods of extra-cavity second harmonic generation of continuous wave single-frequency radiation.

PubMed

Khripunov, Sergey; Kobtsev, Sergey; Radnatarov, Daba

2016-01-20

This work presents for the first time to the best of our knowledge a comparative efficiency analysis among various techniques of extra-cavity second harmonic generation (SHG) of continuous-wave single-frequency radiation in nonperiodically poled nonlinear crystals within a broad range of power levels. Efficiency of nonlinear radiation transformation at powers from 1 W to 10 kW was studied in three different configurations: with an external power-enhancement cavity and without the cavity in the case of single and double radiation pass through a nonlinear crystal. It is demonstrated that at power levels exceeding 1 kW, the efficiencies of methods with and without external power-enhancement cavities become comparable, whereas at even higher powers, SHG by a single or double pass through a nonlinear crystal becomes preferable because of the relatively high efficiency of nonlinear transformation and fairly simple implementation.

Measured radiofrequency exposure during various mobile-phone use scenarios.

PubMed

Kelsh, Michael A; Shum, Mona; Sheppard, Asher R; McNeely, Mark; Kuster, Niels; Lau, Edmund; Weidling, Ryan; Fordyce, Tiffani; Kühn, Sven; Sulser, Christof

2011-01-01

Epidemiologic studies of mobile phone users have relied on self reporting or billing records to assess exposure. Herein, we report quantitative measurements of mobile-phone power output as a function of phone technology, environmental terrain, and handset design. Radiofrequency (RF) output data were collected using software-modified phones that recorded power control settings, coupled with a mobile system that recorded and analyzed RF fields measured in a phantom head placed in a vehicle. Data collected from three distinct routes (urban, suburban, and rural) were summarized as averages of peak levels and overall averages of RF power output, and were analyzed using analysis of variance methods. Technology was the strongest predictor of RF power output. The older analog technology produced the highest RF levels, whereas CDMA had the lowest, with GSM and TDMA showing similar intermediate levels. We observed generally higher RF power output in rural areas. There was good correlation between average power control settings in the software-modified phones and power measurements in the phantoms. Our findings suggest that phone technology, and to a lesser extent, degree of urbanization, are the two stronger influences on RF power output. Software-modified phones should be useful for improving epidemiologic exposure assessment.

Silicon Carbide MOSFET-Based Switching Power Amplifier for Precision Magnet Control

NASA Astrophysics Data System (ADS)

Miller, Kenneth; Ziemba, Timothy; Prager, James; Picard, Julian

2016-10-01

Eagle Harbor Technologies, Inc. (EHT) is using the latest in solid-state switching technologies to advance the state-of-the-art in magnet control for fusion science. Silicon carbide (SiC) MOSFETs offer advantages over IGBTs including lower drive energy requirements, lower conduction and switching losses, and higher switching frequency capabilities. When comparing SiC and traditional silicon-based MOSFETs, SiC MOSFETs provide higher current carrying capability allowing for smaller package weights and sizes and lower operating temperature. To validate the design, EHT has developed a low-power switching power amplifier (SPA), which has been used for precision control of magnetic fields, including rapidly changing the fields in coils. This design has been incorporated in to a high power SPA, which has been bench tested. This high power SPA will be tested at the Helicity Injected Torus (HIT) at the University of Washington. Following successful testing, EHT will produce enough SiC MOSFET-based SPAs to replace all of the units at HIT, which allows for higher frequency operation and an overall increase in pulsed current levels.

Watt-level single-frequency tunable neodymium MOPA fiber laser operating at 915-937 nm

NASA Astrophysics Data System (ADS)

Rota-Rodrigo, S.; Gouhier, B.; Laroche, M.; Zhao, J.; Canuel, B.; Bertoldi, A.; Bouyer, P.; Traynor, N.; Cadier, B.; Robin, T.; Santarelli, G.

2018-02-01

We have developed a Watt-level single-frequency tunable fiber laser in the 915-937 nm spectral window. The laser is based on a neodymium-doped fiber master oscillator power amplifier architecture, with two amplification stages using a 20 mW extended cavity diode laser as seed. The system output power is higher than 2 W from 921 to 933 nm, with a stability better than 1.4% and a low relative intensity noise.

Power control system for a hot gas engine

DOEpatents

Berntell, John O.

1986-01-01

A power control system for a hot gas engine of the type in which the power output is controlled by varying the mean pressure of the working gas charge in the engine has according to the present invention been provided with two working gas reservoirs at substantially different pressure levels. At working gas pressures below the lower of said levels the high pressure gas reservoir is cut out from the control system, and at higher pressures the low pressure gas reservoir is cut out from the system, thereby enabling a single one-stage compressor to handle gas within a wide pressure range at a low compression ratio.

Wind Power Forecasting Error Frequency Analyses for Operational Power System Studies: Preprint

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

Florita, A.; Hodge, B. M.; Milligan, M.

2012-08-01

The examination of wind power forecasting errors is crucial for optimal unit commitment and economic dispatch of power systems with significant wind power penetrations. This scheduling process includes both renewable and nonrenewable generators, and the incorporation of wind power forecasts will become increasingly important as wind fleets constitute a larger portion of generation portfolios. This research considers the Western Wind and Solar Integration Study database of wind power forecasts and numerical actualizations. This database comprises more than 30,000 locations spread over the western United States, with a total wind power capacity of 960 GW. Error analyses for individual sites andmore » for specific balancing areas are performed using the database, quantifying the fit to theoretical distributions through goodness-of-fit metrics. Insights into wind-power forecasting error distributions are established for various levels of temporal and spatial resolution, contrasts made among the frequency distribution alternatives, and recommendations put forth for harnessing the results. Empirical data are used to produce more realistic site-level forecasts than previously employed, such that higher resolution operational studies are possible. This research feeds into a larger work of renewable integration through the links wind power forecasting has with various operational issues, such as stochastic unit commitment and flexible reserve level determination.« less

High-Energy-Density Electrolytic Capacitors

NASA Technical Reports Server (NTRS)

Yen, Shiao-Ping S.; Lewis, Carol R.

1993-01-01

Reductions in weight and volume make new application possible. Supercapacitors and improved ultracapacitors advanced electrolytic capacitors developed for use as electric-load-leveling devices in such applications as electric vehicle propulsion systems, portable power tools, and low-voltage pulsed power supplies. One primary advantage: offer power densities much higher than storage batteries. Capacitors used in pulse mode, with short charge and discharge times. Derived from commercially available ultracapacitors. Made of lightweight materials; incorporate electrode/electrolyte material systems capable of operation at voltages higher than previous electrode/electrolyte systems. By use of innovative designs and manufacturing processes, made in wide range of rated capacitances and in rated operating potentials ranging from few to several hundred volts.

Making Fuel While the Sun Shines.

DOE PAGES

Olzap, Nesrin; Sattler, Christian; Klausner, James F.; ...

2014-10-01

Recent advances in the production of photovoltaic panels have driven down the cost of solar power. Estimates for the levelized cost of electricity from PV range from 10 to 30 cents per kWh. And though this is still higher than the cost of generation from a newly built coal-fired thermal power station, solar power could be the cheapest electricity available in some areas within a few years, according to data from the Energy Information Agency.

Frequency, Power Differential, and Intentionality and the Relationship to Anxiety, Depression, and Self-Esteem for Victims of Bullying

ERIC Educational Resources Information Center

Malecki, Christine Kerres; Demaray, Michelle Kilpatrick; Coyle, Samantha; Geosling, Raymond; Rueger, Sandra Yu; Becker, Lisa Davidson

2015-01-01

Background: Bullying behavior is related to higher levels of internalizing distress and can be defined as including three aspects: frequency, intentionality, and power differential. However, bullying behavior is most often measured using only one aspect: frequency. Objective: The current study investigated the relative importance of several…

Solar power plant and still

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

Taylor, W.P.

This patent describes a solar energy system. It comprises: a water pond which is heated by solar energy; a cover above the pond which transmits solar energy; an air space between the pond and the cover through which warm air and vaporized water move; a chimney which induces the rapid flow of warm humid air into its lower end and delivers such air at its upper end; a fresh water heat sink which receives condensed vapor from the chimney-induced flow; a heat energy driven engine, the power output of which is a function of the temperature difference between higher andmore » lower temperature levels; a first heat exchanger in the engine connected to the top of the chimney, and arranged to convert the vapor condensation energy into the higher temperature level of th engine; a second heat exchanger in the engine arranged to provide the lower temperature of the engine by connection to the heat sink; and power transfer means driven by the temperature differential energy of the engine.« less

Gigawatt peak power generation in a relativistic klystron amplifier driven by 1 kW seed-power

NASA Astrophysics Data System (ADS)

Wu, Y.; Xie, H. Q.; Li, Z. H.; Zhang, Y. J.; Ma, Q. S.

2013-11-01

An S-band high gain relativistic klystron amplifier driven by kW-level RF power is proposed and studied experimentally. In the device, the RF lossy material is introduced to suppress higher mode excitation. An output power of 1.95 GW with a gain of 62.8 dB is obtained in the simulation. Under conditions of an input RF power of 1.38 kW, a microwave pulse with power of 1.9 GW, frequency of 2.86 GHz, and duration of 105 ns is generated in the experiment, and the corresponding gain is 61.4 dB.

Developments in Turbo-Brayton Power Converters

NASA Astrophysics Data System (ADS)

Zagarola, Mark V.; Crowley, Christopher J.; Swift, Walter L.

2003-01-01

Design studies show that a Brayton cycle power unit is an extremely attractive option for thermal-to-electric power conversion on long-duration, space missions. At low power levels (50 to 100 We), a Brayton system should achieve a conversion efficiency between 20% and 40% depending on the radiative heat sink temperature. The expected mass of the converter for these power levels is about 3 kg. The mass of the complete system consisting of the converter, the electronics, a radiator, and a single general purpose heat source should be about 6 kg. The system is modular and the technology is readily scalable to higher power levels (to greater than 10 kWe) where conversion efficiencies of between 28% and 45% are expected, the exact value depending on sink temperature and power level. During a recently completed project, key physical features of the converter were determined, and key operating characteristics were demonstrated for a system of this size. The key technologies in these converters are derived from those which have been developed and successfully implemented in miniature turbo-Brayton cryogenic refrigerators for space applications. These refrigerators and their components have been demonstrated to meet rigorous requirements for vibration emittance and susceptibility, acoustic susceptibility, electromagnetic interference and susceptibility, environmental cycling, and endurance. Our progress in extending the underlying turbo-Brayton cryocooler technologies to thermal-to-electric power converters is the subject of this paper.

Dynamic characteristics of a multi-wavelength Brillouin-Raman fiber laser assisted by multiple four-wave mixing processes in a ring cavity

NASA Astrophysics Data System (ADS)

Shirazi, M. R.; Mohamed Taib, J.; De La Rue, R. M.; Harun, S. W.; Ahmad, H.

2015-03-01

Dynamic characteristics of a multi-wavelength Brillouin-Raman fiber laser (MBRFL) assisted by four-wave mixing have been investigated through the development of Stokes and anti-Stokes lines under different combinations of Brillouin and Raman pump power levels and different Raman pumping schemes in a ring cavity. For a Stokes line of order higher than three, the threshold power was less than the saturation power of its last-order Stokes line. By increasing the Brillouin pump power, the nth order anti-Stokes and the (n+4)th order Stokes power levels were unexpectedly increased almost the same before the Stokes line threshold power. It was also found out that the SBS threshold reduction (SBSTR) depended linearly on the gain factor for the 1st and 2nd Stokes lines, as the first set. This relation for the 3rd and 4th Stokes lines as the second set, however, was almost linear with the same slope before SBSTR -6 dB, then, it approached to the linear relation in the first set when the gain factor was increased to 50 dB. Therefore, the threshold power levels of Stokes lines for a given Raman gain can be readily estimated only by knowing the threshold power levels in which there is no Raman amplification.

Autonomic Dysfunction Correlates with Clinical and Inflammatory Activity in Patients with Crohn's Disease.

PubMed

Engel, Tal; Ben-Horin, Shomron; Beer-Gabel, Marc

2015-10-01

Autonomic dysfunction has been implicated in Crohn's disease (CD). We aimed to investigate heart rate variability (HRV) as a marker of possible autonomic imbalance in patients with CD. Thirty patients with CD and 30 age- and gender-matched healthy controls were enrolled in a prospective cohort study and underwent HRV study. Anxiety level was scored using the STAI questionnaire and CD clinical activity was assessed by Harvey-Bradshaw index. Blood tests including inflammatory markers were obtained for all participants. CD subjects had lower mean blood pressure (85.51 ± 11.07 mm Hg, 91.51 ± 6.99, P = 0.015) and albumin and significantly higher CRP and IL-6 compared with controls (P < 0.002 for all comparisons). Mean HRV values of very low-frequency power and low-frequency power components were significantly lower among CD subjects (P = 0.038 and 0.027, respectively), implying a predominant sympathetic tone. Anxiety level scores were significantly higher among patients with CD for both state anxiety (P = 0.001) and trait anxiety (P < 0.0001). However, patients with active disease had similar anxiety scores as patients in remission, yet had a significantly lower BMI, lower albumin level, and higher CRP and IL-6 levels (P < 0.05 for all comparisons). Moreover, despite similar anxiety scores, patients with active disease had higher pulse rate (P = 0.02) and lower HRV indexes, which correlated with albumin levels(r = 0.7, P = 0.001). Although patients with CD have higher anxiety levels compared with controls, they exhibit depressed HRV independent of this anxiety state and in direct correlation with disease activity and inflammatory markers. These observations suggest an inherent imbalance of autonomic function associated with active inflammation.

A programmable power processor for a 25-kW power module

NASA Technical Reports Server (NTRS)

Lanier, R., Jr.; Kapustka, R. E.; Bush, J. R., Jr.

1979-01-01

A discussion of the power processor for an electrical power system for a 25-kW Power Module that could support the Space Shuttle program during the 1980's and 1990's and which could be a stepping stone to future large space power systems is presented. Trades that led to the selection of a microprocessor-controlled power processor are briefly discussed. Emphasis is given to the power processing equipment that uses a microprocessor to provide versatility that allows multiple use and to provide for future growth by reprogramming output voltage to a higher level (to 120 V from 30 V). Efficiency data from a breadboard programmable power processor are presented, and component selection and design considerations are also discussed.

Governing University Strategy: Perceptions and Practice of Governance and Management Roles

ERIC Educational Resources Information Center

Rytmeister, Catherine

2009-01-01

Intertwined trends of massification, internationalisation and marketisation constitute and drive change in higher education at all levels. Consequences at the institutional level include: increased competition, adoption of corporate management forms, accrual of power to executive management, and greater emphasis on strategy. As Government policy…

Optical gain in 1.3-μm electrically driven dilute nitride VCSOAs

PubMed Central

2014-01-01

We report the observation of room-temperature optical gain at 1.3 μm in electrically driven dilute nitride vertical cavity semiconductor optical amplifiers. The gain is calculated with respect to injected power for samples with and without a confinement aperture. At lower injected powers, a gain of almost 10 dB is observed in both samples. At injection powers over 5 nW, the gain is observed to decrease. For nearly all investigated power levels, the sample with confinement aperture gives slightly higher gain. PMID:24417791

Mitigation of Hot-Spots in Photovoltaic Systems Using Distributed Power Electronics

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

Olalla, Carlos; Hasan, Md. Nazmul; Deline, Chris

In the presence of partial shading and other mismatch factors, bypass diodes may not offer complete elimination of excessive power dissipation due to cell reverse biasing, commonly referred to as hot-spotting in photovoltaic (PV) systems. As a result, PV systems may experience higher failure rates and accelerated ageing. In this paper, a cell-level simulation model is used to assess occurrence of hot-spotting events in a representative residential rooftop system scenario featuring a moderate shading environment. The approach is further used to examine how well distributed power electronics converters mitigate the effects of partial shading and other sources of mismatch bymore » preventing activation of bypass diodes and thereby reducing the chances of heavy power dissipation and hot-spotting in mismatched cells. The simulation results confirm that the occurrence of heavy power dissipation is reduced in all distributed power electronics architectures, and that submodule-level converters offer nearly 100% mitigation of hot-spotting. In addition, the paper further elaborates on the possibility of hot-spot-induced permanent damage, predicting a lifetime energy loss above 15%. In conclusion, this energy loss is fully recoverable with submodule-level power converters that mitigate hot-spotting and prevent the damage.« less

Mitigation of Hot-Spots in Photovoltaic Systems Using Distributed Power Electronics

DOE PAGES

Olalla, Carlos; Hasan, Md. Nazmul; Deline, Chris; ...

2018-03-23

In the presence of partial shading and other mismatch factors, bypass diodes may not offer complete elimination of excessive power dissipation due to cell reverse biasing, commonly referred to as hot-spotting in photovoltaic (PV) systems. As a result, PV systems may experience higher failure rates and accelerated ageing. In this paper, a cell-level simulation model is used to assess occurrence of hot-spotting events in a representative residential rooftop system scenario featuring a moderate shading environment. The approach is further used to examine how well distributed power electronics converters mitigate the effects of partial shading and other sources of mismatch bymore » preventing activation of bypass diodes and thereby reducing the chances of heavy power dissipation and hot-spotting in mismatched cells. The simulation results confirm that the occurrence of heavy power dissipation is reduced in all distributed power electronics architectures, and that submodule-level converters offer nearly 100% mitigation of hot-spotting. In addition, the paper further elaborates on the possibility of hot-spot-induced permanent damage, predicting a lifetime energy loss above 15%. In conclusion, this energy loss is fully recoverable with submodule-level power converters that mitigate hot-spotting and prevent the damage.« less

Soft-Fault Detection Technologies Developed for Electrical Power Systems

NASA Technical Reports Server (NTRS)

Button, Robert M.

2004-01-01

The NASA Glenn Research Center, partner universities, and defense contractors are working to develop intelligent power management and distribution (PMAD) technologies for future spacecraft and launch vehicles. The goals are to provide higher performance (efficiency, transient response, and stability), higher fault tolerance, and higher reliability through the application of digital control and communication technologies. It is also expected that these technologies will eventually reduce the design, development, manufacturing, and integration costs for large, electrical power systems for space vehicles. The main focus of this research has been to incorporate digital control, communications, and intelligent algorithms into power electronic devices such as direct-current to direct-current (dc-dc) converters and protective switchgear. These technologies, in turn, will enable revolutionary changes in the way electrical power systems are designed, developed, configured, and integrated in aerospace vehicles and satellites. Initial successes in integrating modern, digital controllers have proven that transient response performance can be improved using advanced nonlinear control algorithms. One technology being developed includes the detection of "soft faults," those not typically covered by current systems in use today. Soft faults include arcing faults, corona discharge faults, and undetected leakage currents. Using digital control and advanced signal analysis algorithms, we have shown that it is possible to reliably detect arcing faults in high-voltage dc power distribution systems (see the preceding photograph). Another research effort has shown that low-level leakage faults and cable degradation can be detected by analyzing power system parameters over time. This additional fault detection capability will result in higher reliability for long-lived power systems such as reusable launch vehicles and space exploration missions.

Lunar Surface Stirling Power Systems Using Isotope Heat Sources

NASA Technical Reports Server (NTRS)

Schmitz, Paul C.; Penswick, L. Barry; Shaltens, Richard K.

2010-01-01

For many years, NASA has used the decay of plutonium-238 (Pu-238) (in the form of the General Purpose Heat Source (GPHS)) as a heat source for Radioisotope Thermoelectric Generators (RTGs), which have provided electrical power for many NASA missions. While RTGs have an impressive reliability record for the missions in which they have been used, their relatively low thermal to electric conversion efficiency and the scarcity of plutonium-238 (Pu-238) has led NASA to consider other power conversion technologies. NASA is considering returning both robotic and human missions to the lunar surface and, because of the long lunar nights (14.75 Earth days), isotope power systems are an attractive candidate to generate electrical power. NASA is currently developing the Advanced Stirling Radioisotope Generator (ASRG) as a candidate higher efficiency power system that produces greater than 160 W with two GPHS modules at the beginning of life (BOL) (32% efficiency). The ASRG uses the same Pu-238 GPHS modules, which are used in RTG, but by coupling them to a Stirling convertor provides a four-fold reduction in the number of GPHS modules. This study considers the use of americium-241 (Am-241) as a substitute for the Pu-238 in Stirling- convertor-based Radioisotope Power Systems (RPS) for power levels from tens of watts to 5 kWe. The Am-241 is used as a substitute for the Pu-238 in GPHS modules. Depending on power level, different Stirling heat input and removal systems are modeled. It was found that substituting Am-241 GPHS modules into the ASRG reduces power output by about one-fifth while maintaining approximately the same system mass. In order to obtain the nominal 160 W of electrical output of the Pu-238 ASRG requires 10 Am-241 GPHS modules. Higher power systems require changing from conductive coupling heat input and removal from the Stirling convertor to either pumped loops or heat pipes. Liquid metal pumped loops are considered as the primary heat transportation on the hot end and water pumped loop/heat pipe radiator is considered for the heat rejection side for power levels above 1 kWe.

Lunar Surface Stirling Power Systems Using Am-241

NASA Technical Reports Server (NTRS)

Schmitz, Paul C.; Penswick, L. Barry; Shaltens, Richard K.

2009-01-01

For many years NASA has used the decay of Pu-238 (in the form of the General Purpose Heat Source (GPHS)) as a heat source for Radioisotope Thermoelectric Generators (RTG), which have provided electrical power for many NASA missions. While RTG's have an impressive reliability record for the missions in which they have been used, their relatively low thermal to electric conversion efficiency (-5% efficiency) and the scarcity of Plutoinium-238 (Pu-238) has led NASA to consider other power conversion technologies. NASA is considering returning both robotic and human missions to the lunar surface and, because of the long lunar nights (14 earth days) isotope power systems are an attractive candidate to generate electrical power. NASA is currently developing the Advanced Stirling Radioisotope Generator (ASRG) as a candidate higher efficiency power system that produces greater than 160 watts with 2 GPHS modules at the beginning of life (BOL) (-30% efficiency). The ASRG uses the same Pu-238 GPHS modules, which are used in RTG, but by coupling them to a Stirling convertor provides a 4-fold reduction in the number of GPHS modules. This study considers the use of Americium 241 (Am-241) as a substitute for the Pu-238 in Stirling convertor based Radioisotope Power Systems (RPS) for power levels from 1 O's of watts to 5 kWe. The Am-241 is used as a replacement for the Pu-238 in GPHS modules. Depending on power level, different Stirling heat input and removal systems are modeled. It was found that substituting Am-241 GPHS modules into the ASRG reduces power output by about 1/5 while maintaining approximately the same system mass. In order to obtain the nominal 160 watts electrical output of the Pu-238 ASRG requires 10 Am-241 GPHS modules. Higher power systems require changing from conductive coupling heat input and removal from the Stirling convertor to either pumped loops or heat pipes. Liquid metal pumped loops are considered as the primary heat transportation on the hot end and water pumped loop/heat pipe radiator is considered for the heat rejection side for power levels above 1 kWe.

Inventing an Energy Internet: Concepts, Architectures and Protocols for Smart Energy Utilization

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

Tsoukalas, Lefteri

2009-04-29

In recent years, the Internet is revolutionizing information availability much like the Power Grid revolutionized energy availability a century earlier. We will explore the differences and similarities of these two critical infrastructures and identify ways for convergence which may lead to an energy internet. Pricing signals, nodal forecasting, and short-term elasticities are key concepts in smart energy flows respecting the delicate equilibrium involved in generation-demand and aiming at higher efficiencies. We will discuss how intelligent forecasting approaches operating at multiple levels (including device or nodal levels) can ameliorate the challenges of power storage. In addition to higher efficiencies, an energymore » internet may achieve significant reliability and security improvements and offer greater flexibility and transparency in the overall energy-environmental relation.« less

Breast milk provides better antioxidant power than does formula.

PubMed

Aycicek, Ali; Erel, Ozcan; Kocyigit, Abdurrahim; Selek, Sahbettin; Demirkol, Mehmet Resit

2006-06-01

We examined the effect of breast milk on plasma total antioxidant capacity (TAC), total peroxide (TP), and oxidative stress index (OSI), which are biomarkers of oxidative status. Fifty-four healthy term infants 3 to 6 mo of age were fed breast milk or a cow's milk modified formula. Plasma TAC, vitamin C, albumin, bilirubin, and uric acid levels were measured as indexes of antioxidative markers. Plasma TP levels were measured as an oxidative stress marker. The OSI was calculated to assess oxidative status. No significant differences were observed between groups with respect to growth or anthropometric measurements. Plasma uric acid, total protein, and albumin concentrations were slightly higher in the breast-fed group than in the formula-fed group. There was a positive correlation between infant's age and serum albumin levels; between TAC and plasma uric acid, albumin, and total bilirubin; and between plasma iron and TP levels in both groups (r > 0.256, P < 0.05). In addition, there was a negative correlation between plasma iron and TAC (r = -0.267, P = 0.01). Plasma TAC and vitamin C levels were significantly higher in the breast-fed group than in the formula-fed group (P < 0.05). Plasma TP levels and the OSI were higher in the formula-fed group than those in the breast-fed group (P < 0.05). Our data suggest that breast milk provides better antioxidant power than does formula.

Fluidized-bed technology enabling the integration of high temperature solar receiver CSP systems with steam and advanced power cycles

DOE PAGES

Sakadjian, B.; Hu, S.; Maryamchik, M.; ...

2015-06-05

Solar Particle Receivers (SPR) are under development to drive concentrating solar plants (CSP) towards higher operating temperatures to support higher efficiency power conversion cycles. The novel high temperature SPR-based CSP system uses solid particles as the heat transfer medium (HTM) in place of the more conventional fluids such as molten salt or steam used in current state-of-the-art CSP plants. The solar particle receiver (SPR) is designed to heat the HTM to temperatures of 800 °C or higher which is well above the operating temperatures of nitrate-based molten salt thermal energy storage (TES) systems. The solid particles also help overcome somemore » of the other challenges associated with molten salt-based systems such as freezing, instability and degradation. The higher operating temperatures and use of low cost HTM and higher efficiency power cycles are geared towards reducing costs associated with CSP systems. This paper describes the SPR-based CSP system with a focus on the fluidized-bed (FB) heat exchanger and its integration with various power cycles. Furthermore, the SPR technology provides a potential pathway to achieving the levelized cost of electricity (LCOE) target of $0.06/kWh that has been set by the U.S. Department of Energy's SunShot initiative.« less

Fluidized-bed technology enabling the integration of high temperature solar receiver CSP systems with steam and advanced power cycles

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

Sakadjian, B.; Hu, S.; Maryamchik, M.

Solar Particle Receivers (SPR) are under development to drive concentrating solar plants (CSP) towards higher operating temperatures to support higher efficiency power conversion cycles. The novel high temperature SPR-based CSP system uses solid particles as the heat transfer medium (HTM) in place of the more conventional fluids such as molten salt or steam used in current state-of-the-art CSP plants. The solar particle receiver (SPR) is designed to heat the HTM to temperatures of 800 °C or higher which is well above the operating temperatures of nitrate-based molten salt thermal energy storage (TES) systems. The solid particles also help overcome somemore » of the other challenges associated with molten salt-based systems such as freezing, instability and degradation. The higher operating temperatures and use of low cost HTM and higher efficiency power cycles are geared towards reducing costs associated with CSP systems. This paper describes the SPR-based CSP system with a focus on the fluidized-bed (FB) heat exchanger and its integration with various power cycles. Furthermore, the SPR technology provides a potential pathway to achieving the levelized cost of electricity (LCOE) target of $0.06/kWh that has been set by the U.S. Department of Energy's SunShot initiative.« less

Primordial power spectrum features and consequences

NASA Astrophysics Data System (ADS)

Goswami, G.

2014-03-01

The present Cosmic Microwave Background (CMB) temperature and polarization anisotropy data is consistent with not only a power law scalar primordial power spectrum (PPS) with a small running but also with the scalar PPS having very sharp features. This has motivated inflationary models with such sharp features. Recently, even the possibility of having nulls in the power spectrum (at certain scales) has been considered. The existence of these nulls has been shown in linear perturbation theory. What shall be the effect of higher order corrections on such nulls? Inspired by this question, we have attempted to calculate quantum radiative corrections to the Fourier transform of the 2-point function in a toy field theory and address the issue of how these corrections to the power spectrum behave in models in which the tree-level power spectrum has a sharp dip (but not a null). In particular, we have considered the possibility of the relative enhancement of radiative corrections in a model in which the tree-level spectrum goes through a dip in power at a certain scale. The mode functions of the field (whose power spectrum is to be evaluated) are chosen such that they undergo the kind of dynamics that leads to a sharp dip in the tree level power spectrum. Next, we have considered the situation in which this field has quartic self interactions, and found one loop correction in a suitably chosen renormalization scheme. Thus, we have attempted to answer the following key question in the context of this toy model (which is as important in the realistic case): In the chosen renormalization scheme, can quantum radiative corrections be enhanced relative to tree-level power spectrum at scales, at which sharp dips appear in the tree-level spectrum?

The Atacama Cosmology Telescope: A Measurement of the Cosmic Microwave Background Power Spectrum at 148 AND 218 GHz from the 2008 Southern Survey

NASA Technical Reports Server (NTRS)

Das, Sudeep; Marriage, Tobias A.; Ade, Peter A. R.; Aguirre, Paula; Amiri, Mandana; Appel, John W.; Barrientos, L. Felipe; Battistelli, Elia A.; Bond, J. Richard; Brown, Ben;

Design considerations for large space electric power systems

NASA Technical Reports Server (NTRS)

Renz, D. D.; Finke, R. C.; Stevens, N. J.; Triner, J. E.; Hansen, I. G.

1983-01-01

As power levels of spacecraft rise to the 50 to 100 kW range, it becomes apparent that low voltage (28 V) dc power distribution and management systems will not operate efficiently at these higher power levels. The concept of transforming a solar array voltage at 150 V dc into a 1000 V ac distribution system operating at 20 kHz is examined. The transformation is accomplished with series-resonant inverter by using a rotary transformer to isolate the solar array from the spacecraft. The power can then be distributed in any desired method such as three phase delta to delta. The distribution voltage can be easily transformed to any desired load voltage and operating frequency. The reasons for the voltage limitations on the solar array due to plasma interactions and the many advantages of a high voltage, high frequency at distribution system are discussed.

14 CFR 33.49 - Endurance test.

Code of Federal Regulations, 2012 CFR

2012-01-01

... higher gear ratio under sea level conditions. The condition for operation for the alternate 5 minutes in... suppress detonation. (d) Helicopter engines. To be eligible for use on a helicopter each engine must either... sea level carburetor entrance pressure, if 105 percent of the rated maximum continuous power is not...

14 CFR 33.49 - Endurance test.

Code of Federal Regulations, 2011 CFR

2011-01-01

... higher gear ratio under sea level conditions. The condition for operation for the alternate 5 minutes in... suppress detonation. (d) Helicopter engines. To be eligible for use on a helicopter each engine must either... sea level carburetor entrance pressure, if 105 percent of the rated maximum continuous power is not...

The New Rules of Engagement

ERIC Educational Resources Information Center

Mitchell, Brian C.

2013-01-01

The many levels of hierarchy in higher education are a kaleidoscope of power struggles and egos. The responsibilities of each level can be unclear, leading to administrative chaos. Above all, trustees who overstep their authority and neglect to direct policy can weaken an institution's mission and diminish its educational product. In 2008, as the…

Cascaded die mountings with spring-loaded contact-bond options

DOEpatents

Hsu, John S.; Adams, Donald J.; Su, Gui-Jia; Marlino, Laura D.; Ayers, Curtis W.; Coomer, Chester

2005-08-16

A cascaded die mounting device and method using spring contacts for die attachment, with or without metallic bonds between the contacts and the dies, is disclosed. One embodiment is for the direct refrigerant cooling of an inverter/converter carrying higher power levels than most of the low power circuits previously taught, and does not require using a heat sink.

Method of making cascaded die mountings with springs-loaded contact-bond options

DOEpatents

Hsu, John S [Oak Ridge, TN; Adams, Donald J [Knoxville, TN; Su, Gui-Jia [Knoxville, TN; Marlino, Laura D [Oak Ridge, TN; Ayers, Curtis W [Kingston, TN; Coomer, Chester [Knoxville, TN

2007-06-19

A cascaded die mounting device and method using spring contacts for die attachment, with or without metallic bonds between the contacts and the dies, is disclosed. One embodiment is for the direct refrigerant cooling of an inverter/converter carrying higher power levels than most of the low power circuits previously taught, and does not require using a heat sink.

Who Controls the Board in Non-Profit Organizations? The Case of Private Higher Education Institutions in Colombia

ERIC Educational Resources Information Center

Bradford, Henry; Guzmán, Alexander; Restrepo, José Manuel; Trujillo, María-Andrea

2018-01-01

How should the governance system in a non-membership non-profit organization be designed? This organizational form has no shareholders; instead, donors provide funds. Thus, at the organizational level, the board of directors could have all the power. Under this legal form, who controls the board? If too powerful, boards could misuse resources or…

A Safe and Interactive Method of Illuminating Discharge Tubes for Studying Emission Spectra

ERIC Educational Resources Information Center

Lu, Zhe

2012-01-01

Discharge tubes are useful tools for teaching emission spectra and the discrete energy levels of the Bohr model. A new setup uses a plasma globe to illuminate the discharge tube and allows a higher degree of interactivity owing to the omission of a traditional, high-voltage power source. The decreased power consumption also reduces the heating of…

Benzophenone-3 ultrasound degradation in a multifrequency reactor: Response surface methodology approach.

PubMed

Vega-Garzon, Lina Patricia; Gomez-Miranda, Ingry Natalia; Peñuela, Gustavo A

2018-05-01

Response Surface Methodology was used for optimizing operating variables for a multi-frequency ultrasound reactor using BP-3 as a model compound. The response variable was the Triclosan degradation percent after 10 sonication min. Frequency at levels from 574, 856 and 1134 kHz were used. Power density, pulse time (PT), silent time (ST) and PT/ST ratio effects were also analyzed. 2 2 and 2 3 experimental designs were used for screening purposes and a central composite design was used for optimization. An optimum value of 79.2% was obtained for a frequency of 574 kHz, a power density of 200 W/L, and a PT/ST ratio of 10. Significant variables were frequency and power level, the first having an optimum value after which degradation decreases while power density level had a strong positive effect on the whole operational range. PT, ST, and PT/ST ratio were not significant variables although it was shown that pulsed mode ultrasound has better degradation rates than continuous mode ultrasound; the effect less significant at higher power levels. Copyright © 2017. Published by Elsevier B.V.

[Contribution of genetic polymorphism to the formation of individual genome sensitivity in workers engaged in heat and power industry].

PubMed

Minina, V I; Savchenko, Ia A; Bakanova, M L; Ostaptseva, A V; Popova, O S; Shatalina, I V; Akin'china, L V; Druzhinin, V G

2011-01-01

The paper presents the results of investigating an association between the frequency of chromosome aberrations and the CYP1A1, CYP1A2*1F GSTM1, and GSTT1 genes involved in xenobiotic biotransformation in workers engaged in heat and power engineering. The group of workers is shown to have a significantly higher rate of metaphases with aberrations (4.03 +/- 0.17%; n = 231) than the control group (2.06 +/- 0.17%; n = 141). Cytogenetic disorders are not found to depend on gender, age, and length of service. The study indicated that the level of chromosome aberrations was significantly higher in carriers of the CTP1A1 C/C, GSTM1 0/0 and GSTT1 0/0 genotypes. In individuals with a combination of the GSTM1 0/0 and GSTT1 0/0 genotypes, the level of chromosome aberrations was ascertained to be significantly higher than that in those with the protective form of these genes.

Testing of YUH-61A helicopter transmission in NASA Lewis 2240-kW (3000-hp facility

NASA Technical Reports Server (NTRS)

Mitchell, A. M.; Oswald, F. B.; Schuller, F. T.

1986-01-01

A helicopter transmission that was being considered for the Army's Utility Tactical Transport Attack System (UTTAS) was tested in the NASA Lewis 2240-kW (3000-hp) test facility to obtain the transmission's operational data. The results will form a vibration and efficiency data base for evaluation similar-class helicopter transmissions. The transmission's mechanical efficiency was determined to be 98.7 percent at its rated power level of 2080 kW (2792 hp). At power levels up to 113 percent of rated the transmission displayed 56 percent higher vibration acceleration levels on the right input than on the left input. Both vibration signature analysis and final visual inspection indicated that the right input spiral-bevel gear had poor contact patterns. The highest vibration meter level was 52 g's rms at the accessory gear, which had free-wheeling gearsets. At 113 percent power and 100 percent rated speed the vibration meter levels generally ranged from 3 to 25 g's rms.

Advanced spacecraft fuel cell systems

NASA Technical Reports Server (NTRS)

Thaller, L. H.

1972-01-01

The development and characteristics of advanced spacecraft fuel cell systems are discussed. The system is designed to operate on low pressure, propulsion grade hydrogen and oxygen. The specific goals are 10,000 hours of operation with refurbishment, 20 pounds per kilowatt at a sustained power of 7 KW, and 21 KW peaking capability for durations of two hours. The system rejects waste heat to the spacecraft cooling system at power levels up to 7 KW. At higher powers, the system automatically transfers to open cycle operation with overboard steam venting.

Advanced Small Free-Piston Stirling Convertors for Space Power Applications

NASA Astrophysics Data System (ADS)

Wood, J. Gary; Lane, Neill

2004-02-01

This paper reports on the current status of an advanced 35 We free-piston Stirling convertor currently being developed under NASA SBIR Phase II funding. Also described is a further advanced and higher performance ~80 watt free-piston convertor being developed by Sunpower and Boeing/Rocketdyne for NASA under NRA funding. Exceptional overall convertor (engine plus linear alternator) thermodynamic performance (greater than 50% of Carnot) with specific powers around 100 We /kg appear reasonable at these low power levels.

Optimal Design in Three-Level Block Randomized Designs with Two Levels of Nesting: An ANOVA Framework with Random Effects

ERIC Educational Resources Information Center

Konstantopoulos, Spyros

2013-01-01

Large-scale experiments that involve nested structures may assign treatment conditions either to subgroups such as classrooms or to individuals such as students within subgroups. Key aspects of the design of such experiments include knowledge of the variance structure in higher levels and the sample sizes necessary to reach sufficient power to…

New Active Remote-sensing Capabilities: Laser Ablation Spectrometer and Lidar Atmospheric Species Profile Measurements

NASA Technical Reports Server (NTRS)

DeYoung, R. J.; Bergstralh, J. T.

2005-01-01

Introduction: With the anticipated development of high-capacity fission power and electric propulsion for deep-space missions, it will become possible to propose experiments that demand higher power than current technologies (e.g. radioisotope power sources) provide. Jupiter Icy Moons Orbiter (JIMO), the first mission in the Project Prometheus program, will explore the icy moons of Jupiter with a suite of high-capability experiments that take advantage of the high power levels (and indirectly, the high data rates) that fission power affords. This abstract describes two high-capability active-remote-sensing experiments that will be logical candidates for subsequent Prometheus-class missions.

Mission Assessment of the Faraday Accelerator with Radio-frequency Assisted Discharge (FARAD)

NASA Technical Reports Server (NTRS)

Dankanich, John W.; Polzin, Kurt A.

2008-01-01

Pulsed inductive thrusters have typically been considered for future, high-power, missions requiring nuclear electric propulsion. These high-power systems, while promising equivalent or improved performance over state-of-the-art propulsion systems, presently have no planned missions for which they are well suited. The ability to efficiently operate an inductive thruster at lower energy and power levels may provide inductive thrusters near term applicability and mission pull. The Faraday Accelerator with Radio-frequency Assisted Discharge concept demonstrated potential for a high-efficiency, low-energy pulsed inductive thruster. The added benefits of energy recapture and/or pulse compression are shown to enhance the performance of the pulsed inductive propulsion system, yielding a system that con compete with and potentially outperform current state-of-the-art electric propulsion technologies. These enhancements lead to mission-level benefits associated with the use of a pulsed inductive thruster. Analyses of low-power near to mid-term missions and higher power far-term missions are undertaken to compare the performance of pulsed inductive thrusters with that delivered by state-of-the-art and development-level electric propulsion systems.

Thermal structure and heat balance of the outer planets

NASA Technical Reports Server (NTRS)

Conrath, B. J.; Hanel, R. A.; Samuelson, R. E.

1989-01-01

Current knowledge of the thermal structure and energy balance of the outer planets is summarized. The Voyager spacecraft experiments have provided extensive new information on the atmospheric temperatures and energetics of Jupiter, Saturn and Uranus. All three planets show remarkably small global-scale horizontal thermal contrast, indicating efficient redistribution of heat within the atmospheres or interiors. Horizontal temperature gradients on the scale of the zonal jets indicate that the winds decay with height in the upper troposphere. This suggests that the winds are driven at deeper levels and are subjected to frictional damping of unknown origin at higher levels. Both Jupiter and Saturn have internal power sources equal to about 70 percent of the absorbed solar power. This result is consistent with the view that significant helium differentiation has occurred on Saturn. Uranus has an internal power no greater than 13 percent of the absorbed solar power, while earth-based observations suggest Neptune has an internal power in excess of 100 percent of the absorbed solar power.

High-power piezoelectric acoustic-electric power feedthru for metal walls

NASA Astrophysics Data System (ADS)

Bao, Xiaoqi; Biederman, Will; Sherrit, Stewart; Badescu, Mircea; Bar-Cohen, Yoseph; Jones, Christopher; Aldrich, Jack; Chang, Zensheu

2008-03-01

Piezoelectric acoustic-electric power feed-through devices transfer electric power wirelessly through a solid wall using elastic waves. This approach allows for the elimination of the need for holes through structures for cabling or electrical feed-thrus . The technology supplies power to electric equipment inside sealed containers, vacuum or pressure vessels, etc where holes in the wall are prohibitive or may result in significant performance degradation or requires complex designs. In the our previous work, 100-W of electric power was transferred through a metal wall by a small, piezoelectric device with a simple-structure. To meet requirements of higher power applications, the feasibility to transfer kilowatts level power was investigated. Pre-stressed longitudinal piezoelectric feed-thru devices were analyzed by finite element modeling. An equivalent circuit model was developed to predict the characteristics of power transfer to different electric loads. Based on the analytical results, a prototype device was designed, fabricated and successfully demonstrated to transfer electric power at a level of 1-kW. Methods of minimizing plate wave excitation on the wall were also analyzed. Both model analysis and experimental results are presented in detail in this paper.

Impact of Uncoordinated Plug-in Electric Vehicle Charging on Residential Power Demand

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

Muratori, Matteo

Electrification of transport offers opportunities to increase energy security, reduce carbon emissions, and improve local air quality. Plug-in electric vehicles (PEVs) are creating new connections between the transportation and electric sectors, and PEV charging will create opportunities and challenges in a system of growing complexity. Here, I use highly resolved models of residential power demand and PEV use to assess the impact of uncoordinated in-home PEV charging on residential power demand. While the increase in aggregate demand might be minimal even for high levels of PEV adoption, uncoordinated PEV charging could significantly change the shape of the aggregate residential demand,more » with impacts for electricity infrastructure, even at low adoption levels. Clustering effects in vehicle adoption at the local level might lead to high PEV concentrations even if overall adoption remains low, significantly increasing peak demand and requiring upgrades to the electricity distribution infrastructure. This effect is exacerbated when adopting higher in-home power charging.« less

Impact of uncoordinated plug-in electric vehicle charging on residential power demand

NASA Astrophysics Data System (ADS)

Muratori, Matteo

2018-03-01

Electrification of transport offers opportunities to increase energy security, reduce carbon emissions, and improve local air quality. Plug-in electric vehicles (PEVs) are creating new connections between the transportation and electric sectors, and PEV charging will create opportunities and challenges in a system of growing complexity. Here, I use highly resolved models of residential power demand and PEV use to assess the impact of uncoordinated in-home PEV charging on residential power demand. While the increase in aggregate demand might be minimal even for high levels of PEV adoption, uncoordinated PEV charging could significantly change the shape of the aggregate residential demand, with impacts for electricity infrastructure, even at low adoption levels. Clustering effects in vehicle adoption at the local level might lead to high PEV concentrations even if overall adoption remains low, significantly increasing peak demand and requiring upgrades to the electricity distribution infrastructure. This effect is exacerbated when adopting higher in-home power charging.

GaAs VLSI technology and circuit elements for DSP

NASA Astrophysics Data System (ADS)

Mikkelson, James M.

1990-10-01

Recent progress in digital GaAs circuit performance and complexity is presented to demonstrate the current capabilities of GaAs components. High density GaAs process technology and circuit design techniques are described and critical issues for achieving favorable complexity speed power and cost tradeoffs are reviewed. Some DSP building blocks are described to provide examples of what types of DSP systems could be implemented with present GaAs technology. DIGITAL GaAs CIRCUIT CAPABILITIES In the past few years the capabilities of digital GaAs circuits have dramatically increased to the VLSI level. Major gains in circuit complexity and power-delay products have been achieved by the use of silicon-like process technologies and simple circuit topologies. The very high speed and low power consumption of digital GaAs VLSI circuits have made GaAs a desirable alternative to high performance silicon in hardware intensive high speed system applications. An example of the performance and integration complexity available with GaAs VLSI circuits is the 64x64 crosspoint switch shown in figure 1. This switch which is the most complex GaAs circuit currently available is designed on a 30 gate GaAs gate array. It operates at 200 MHz and dissipates only 8 watts of power. The reasons for increasing the level of integration of GaAs circuits are similar to the reasons for the continued increase of silicon circuit complexity. The market factors driving GaAs VLSI are system design methodology system cost power and reliability. System designers are hesitant or unwilling to go backwards to previous design techniques and lower levels of integration. A more highly integrated system in a lower performance technology can often approach the performance of a system in a higher performance technology at a lower level of integration. Higher levels of integration also lower the system component count which reduces the system cost size and power consumption while improving the system reliability. For large gate count circuits the power per gate must be minimized to prevent reliability and cooling problems. The technical factors which favor increasing GaAs circuit complexity are primarily related to reducing the speed and power penalties incurred when crossing chip boundaries. Because the internal GaAs chip logic levels are not compatible with standard silicon I/O levels input receivers and output drivers are needed to convert levels. These I/O circuits add significant delay to logic paths consume large amounts of power and use an appreciable portion of the die area. The effects of these I/O penalties can be reduced by increasing the ratio of core logic to I/O on a chip. DSP operations which have a large number of logic stages between the input and the output are ideal candidates to take advantage of the performance of GaAs digital circuits. Figure 2 is a schematic representation of the I/O penalties encountered when converting from ECL levels to GaAs

Neutron activation analysis of thermal power plant ash and surrounding area soils.

PubMed

Al-Masri, M S; Haddad, Kh; Alsomel, N; Sarhil, A

2015-08-01

Elemental concentrations of As, Cd, Co, Cr, Fe, Hg, Mo, Ni, Se, and Zn have been determined in fly and bottom ash collected from Syrian power plants fired by heavy oil and natural gas using instrumental neutron activation analysis. The results showed that all elements were more concentrated in fly ash than in the fly ash; there was a clear increasing trend of the elemental concentrations in the fly ash along the flue gas pathway. The annual emission of elements was estimated. Elemental concentrations were higher inside the campus area than in surrounding areas, and the lowest values were found in natural-gas-fired power plant. In addition, the levels have decreased as the distance from power plant campus increases. However, the levels in the surrounding villages were within the Syrian standard for agriculture soil.

Higher Ed. Gets Voting Rights on Assessments

ERIC Educational Resources Information Center

Gewertz, Catherine

2012-01-01

A group of states that is designing tests for the common academic standards has taken a key step to ensure that the assessments reflect students' readiness for college-level work: It gave top higher education officials from member states voting power on test-design questions that are closest to the heart of the college-readiness question. At its…

Effect of modulation p-doping level on multi-state lasing in InAs/InGaAs quantum dot lasers having different external loss

NASA Astrophysics Data System (ADS)

Korenev, V. V.; Savelyev, A. V.; Maximov, M. V.; Zubov, F. I.; Shernyakov, Yu. M.; Kulagina, M. M.; Zhukov, A. E.

2017-09-01

The influence of the modulation p-doping level on multi-state lasing in InAs/InGaAs quantum dot (QD) lasers is studied experimentally for devices having various external losses. It is shown that in the case of short cavities (high external loss), there is an increase in the lasing power component corresponding to the ground-state optical transitions of QDs as the p-doping level grows. However, in the case of long cavities (small external loss), higher dopant concentrations may have an opposite effect on the output power. Based on these observations, an optimal design of laser geometry and an optimal doping level are discussed.

A social relations model of observed family negativity and positivity using a genetically informative sample.

PubMed

Rasbash, Jon; Jenkins, Jennifer; O'Connor, Thomas G; Tackett, Jennifer; Reiss, David

2011-03-01

The goal of this study was to investigate individual and relationship influences on expressions of negativity and positivity in families. Parents and adolescents were observed in a round-robin design in a sample of 687 families. Data were analyzed using a multilevel social relations model. In addition, genetic contributions were estimated for actor effects. Children showed higher mean levels of negativity and lower mean levels of positivity as actors than did parents. Mothers were found to express and elicit higher mean levels of positivity and negativity than fathers. Actor effects were much stronger than partner effects, accounting for between 18%-39% of the variance depending on the actor and the outcome. Genetic (35%) and shared environmental (19%) influences explained a substantial proportion of the actor effect variance for negativity. Dyadic reciprocities were lowest in dyads with a high power differential (i.e., parent-child dyads) and highest for dyads with equal power (sibling and marital dyads). (c) 2011 APA, all rights reserved

Introductory Textbooks and Plagiarism in Higher Education: A Case Study from Economics.

ERIC Educational Resources Information Center

Richardson, Paul

2002-01-01

Textbooks are powerful technologies that are foundational to introductory level courses. In the research site of an introductory economic classroom, the textbook is positioned as having status similar to that of a canonical religious text. This study investigated how student reading and writing can be problematic when introductory level courses…

Influence of resonator length on catastrophic optical damage in high-power AlGaInP broad-area lasers

NASA Astrophysics Data System (ADS)

Bou Sanayeh, Marwan

2017-05-01

The increasing importance of extracting high optical power out of semiconductor lasers motivated several studies in catastrophic optical damage (COD) level improvement. In this study, the influence of the resonator length in high-power broad-area (BA) AlGaInP lasers on COD is presented. For the analyses, several 638 nm AlGaInP 60 μm BA lasers from the same wafer were used. Resonator lengths of 900, 1200, 1500, and 1800 μm were compared. In order to independently examine the effect of the resonator length on the maximum power reached by the lasers before COD (PCOD), the lasers used are uncoated and unmounted, and PCOD under pulsed mode was determined. It was found that higher output powers and eventually higher PCOD can be achieved using longer resonators; however, it was also found that this is mainly useful when working at high output powers far away from the laser threshold, since the threshold current and slope efficiency worsen when the resonator length increases.

On- and off-eye spherical aberration of soft contact lenses and consequent changes of effective lens power.

PubMed

Dietze, Holger H; Cox, Michael J

2003-02-01

Soft contact lenses produce a significant level of spherical aberration affecting their power on-eye. A simple model assuming that a thin soft contact lens aligns to the cornea predicts that these effects are similar on-eye and off-eye. The wavefront aberration for 17 eyes and 33 soft contact lenses on-eye was measured with a Shack-Hartmann wavefront sensor. The Zernike coefficients describing the on-eye spherical aberration of the soft contact lens were compared with off-eye ray-tracing results. Paraxial and effective lens power changes were determined. The model predicts the on-eye spherical aberration of soft contact lenses closely. The resulting power change for a +/- 7.00 D spherical soft contact lens is +/- 0.5 D for a 6-mm pupil diameter and +/- 0.1 D for a 3-mm pupil diameter. Power change is negligible for soft contact lenses corrected for off-eye spherical aberration. For thin soft contact lenses, the level of spherical aberration and the consequent power change is similar on-eye and off-eye. Soft contact lenses corrected for spherical aberration in air will be expected to be aberration-free on-eye and produce only negligibly small power changes. For soft contact lenses without aberration correction, for higher levels of ametropia and large pupils, the soft contact lens power should be determined with trial lenses with their power and p value similar to the prescribed lens. The benefit of soft contact lenses corrected for spherical aberration depends on the level of ocular spherical aberration.

Early commercial demonstration of space solar power using ultra-lightweight arrays

NASA Astrophysics Data System (ADS)

Reed, Kevin; Willenberg, Harvey J.

2009-11-01

Space solar power shows great promise for future energy sources worldwide. Most central power stations operate with power capacity of 1000 MW or greater. Due to launch size limitations and specific power of current, rigid solar arrays, the largest solar arrays that have flown in space are around 50 kW. Thin-film arrays offer the promise of much higher specific power and deployment of array sizes up to several MW with current launch vehicles. An approach to early commercial applications for space solar power to distribute power to charge hand-held, mobile battery systems by wireless power transmission (WPT) from thin-film solar arrays in quasi-stationary orbits will be presented. Four key elements to this prototype will be discussed: (1) Space and near-space testing of prototype wireless power transmission by laser and microwave components including WPT space to space and WPT space to near-space HAA transmission demonstrations; (2) distributed power source for recharging hand-held batteries by wireless power transmission from MW space solar power systems; (3) use of quasi-geostationary satellites to generate electricity and distribute it to targeted areas; and (4) architecture and technology for ultra-lightweight thin-film solar arrays with specific energy exceeding 1 kW/kg. This approach would yield flight demonstration of space solar power and wireless power transmission of 1.2 MW. This prototype system will be described, and a roadmap will be presented that will lead to still higher power levels.

Domestic decision-making power, social support, and postpartum depression symptoms among immigrant and native women in Taiwan.

PubMed

Chien, Li-Yin; Tai, Chen-Jei; Yeh, Mei-Chiang

2012-01-01

Domestic decision-making power is an integral part of women's empowerment. No study has linked domestic decision-making power and social support concurrently to postpartum depression and compared these between immigrant and native populations. The aim of this study was to examine domestic decision-making power and social support and their relationship to postpartum depressive symptoms among immigrant and native women in Taiwan. This cross-sectional survey included 190 immigrant and 190 native women who had delivered healthy babies during the past year in Taipei City. Depression was measured using the Edinburgh Postnatal Depression Scale, with a cutoff score of 10. Logistic regression was used to determine the factors associated with postpartum depression symptoms. Immigrant mothers had significantly higher prevalence of postpartum depression symptoms (41.1% vs. 8.4%) and had significantly lower levels of domestic decision-making power and social support than native mothers did. Logistic regression showed that insufficient family income was associated with an increased risk of postpartum depression symptoms, whereas social support and domestic decision-making power levels were associated negatively with postpartum depression symptoms. After accounting for these factors, immigrant women remained at higher risk of postpartum depression symptoms than native women did, odds ratio = 2.59, 95% CI [1.27, 5.28]. Domestic decision-making power and social support are independent protective factors for postpartum depression symptoms among immigrant and native women in Taiwan. Social support and empowerment interventions should be tested to discover whether they are able to prevent or alleviate postpartum depression symptoms, with special emphasis on immigrant mothers.

Modular Integrated Stackable Layers (MISL) 1.1 Design Specification. Design Guideline Document

NASA Technical Reports Server (NTRS)

Yim, Hester J.

2012-01-01

This document establishes the design guideline of the Modular Instrumentation Data Acquisition (MI-DAQ) system in utilization of several designs available in EV. The MI- DAQ provides the options to the customers depending on their system requirements i.e. a 28V interface power supply, a low power battery operated system, a low power microcontroller, a higher performance microcontroller, a USB interface, a Ethernet interface, a wireless communication, various sensor interfaces, etc. Depending on customer's requirements, the each functional board can be stacked up from a bottom level of power supply to a higher level of stack to provide user interfaces. The stack up of boards are accomplished by a predefined and standardized power bus and data bus connections which are included in this document along with other physical and electrical guidelines. This guideline also provides information for a new design options. This specification is the product of a collaboration between NASA/JSC/EV and Texas A&M University. The goal of the collaboration is to open source the specification and allow outside entities to design, build, and market modules that are compatible with the specification. NASA has designed and is using numerous modules that are compatible to this specification. A limited number of these modules will also be released as open source designs to support the collaboration. The released designs are listed in the Applicable Documents.

Impact of applied ultrasonic power on the low temperature drying of apple.

PubMed

Santacatalina, J V; Contreras, M; Simal, S; Cárcel, J A; Garcia-Perez, J V

2016-01-01

Low temperature drying (LTD) allows high-quality dried products to be obtained, preserving the nutritional properties of fresh foods better than conventional drying, but it is a time-consuming operation. Power ultrasound (US) could be used to intensify LTD, but it should be taken into account that process variables, such as the level of applied power, have an influence on the magnitude and extension of the ultrasonic effects. Therefore, the aim of this work was to assess the influence of the level of applied ultrasonic power on the LTD of apple, analyzing the drying kinetics and the quality of the dried product. For that purpose, apple (Malus domestica cv. Granny Smith) cubes (8.8mm side) were dried (2m/s) at two different temperatures (10 and -10°C), without and with (25, 50 and 75 W) US application. In the dried apple, the rehydration kinetics, hardness, total phenolic content, antioxidant capacity and microstructure were analyzed to evaluate the impact of the level of applied ultrasonic power. At both temperatures, 10 and -10°C, the higher the ultrasonic power level, the shorter the drying time; the maximum shortening of the drying time achieved was 80.3% (at -10°C and 75 W). The ultrasonic power level did not significantly (p<0.05) affect the quality parameters analyzed. Therefore, US could be considered a non-thermal method of intensifying the LTD of fruits, like apple, with only a mild impact on the quality of the dried product. Copyright © 2015 Elsevier B.V. All rights reserved.

Experimental clean combustor program: Diesel no. 2 fuel addendum, phase 3

NASA Technical Reports Server (NTRS)

Gleason, C. C.; Bahr, D. W.

1979-01-01

A CF6-50 engine equipped with an advanced, low emission, double annular combustor was operated 4.8 hours with No. 2 diesel fuel. Fourteen steady-state operating conditions ranging from idle to full power were investigated. Engine/combustor performance and exhaust emissions were obtained and compared to JF-5 fueled test results. With one exception, fuel effects were very small and in agreement with previously obtained combustor test rig results. At high power operating condition, the two fuels produced virtually the same peak metal temperatures and exhaust emission levels. At low power operating conditions, where only the pilot stage was fueled, smoke levels tended to be significantly higher with No. 2 diesel fuel. Additional development of this combustor concept is needed in the areas of exit temperature distribution, engine fuel control, and exhaust emission levels before it can be considered for production engine use.

Musical genre-dependent behavioural and EEG signatures of action planning. A comparison between classical and jazz pianists.

PubMed

Bianco, R; Novembre, G; Keller, P E; Villringer, A; Sammler, D

2018-04-01

It is well established that musical training induces sensorimotor plasticity. However, there are remarkable differences in how musicians train for proficient stage performance. The present EEG study outlines for the first time clear-cut neurobiological differences between classical and jazz musicians at high and low levels of action planning, revealing genre-specific cognitive strategies adopted in production. Pianists imitated chord progressions without sound that were manipulated in terms of harmony and context length to assess high-level planning of sequence-structure, and in terms of the manner of playing to assess low-level parameter specification of single acts. Jazz pianists revised incongruent harmonies faster as revealed by an earlier reprogramming negativity and beta power decrease, hence neutralising response costs, albeit at the expense of a higher number of manner errors. Classical pianists in turn experienced more conflict during incongruent harmony, as shown by theta power increase, but were more ready to implement the required manner of playing, as indicated by higher accuracy and beta power decrease. These findings demonstrate that specific demands and action focus of training lead to differential weighting of hierarchical action planning. This suggests different enduring markers impressed in the brain when a musician practices one or the other style. Copyright © 2018 Elsevier Inc. All rights reserved.

Effects of forward motion on jet and core noise

NASA Technical Reports Server (NTRS)

Low, J. K. C.

1977-01-01

A study was conducted to investigate the effects of forward motion on both jet and core noise. Measured low-frequency noise from static-engine and from flyover tests with a DC-9-30 powered by JT8D-109 turbofan engines and with a DC-10-40 powered by JT9D-59A turbofan engines was separated into jet- and core noise components. Comparisons of the static and the corresponding in-flight jet- and core-noise components are presented. The results indicate that for the DC-9 airplane at low power settings, where core noise is predominant, the effect of convective amplification on core-noise levels is responsible for the higher in-flight low-frequency noise levels in the inlet quadrant. Similarly, it was found that for the DC-10 airplane with engines mounted under the wings and flaps and flap deflection greater than 30 degrees, the contribution from jet-flap-interaction noise is as much as 5 dB in the inlet quadrant and is responsible for higher in-flight low-frequency noise levels during approach conditions. Those results indicate that to properly investigate flight effects, it is important to consider the noise contributions from other low-frequency sources, such as the core and the jet-flap interaction.

Room for improvement: An examination of advance care planning documentation among gynecologic oncology patients.

PubMed

Brown, Alaina J; Shen, Megan Johnson; Urbauer, Diana; Taylor, Jolyn; Parker, Patricia A; Carmack, Cindy; Prescott, Lauren; Kolawole, Elizabeth; Rosemore, Carly; Sun, Charlotte; Ramondetta, Lois; Bodurka, Diane C

2016-09-01

The goals of this study were: (1) to evaluate patients' knowledge regarding advance directives and completion rates of advance directives among gynecologic oncology patients and (2) to examine the association between death anxiety, disease symptom burden, and patient initiation of advance directives. 110 gynecologic cancer patients were surveyed regarding their knowledge and completion of advance directives. Patients also completed the MD Anderson Symptom Inventory (MDASI) scale and Templer's Death Anxiety Scale (DAS). Descriptive statistics were utilized to examine characteristics of the sample. Fisher's exact tests and 2-sample t-tests were utilized to examine associations between key variables. Most patients were white (76.4%) and had ovarian (46.4%) or uterine cancer (34.6%). Nearly half (47.0%) had recurrent disease. The majority of patients had heard about advance directives (75%). Only 49% had completed a living will or medical power of attorney. Older patients and those with a higher level of education were more likely to have completed an advance directive (p<0.01). Higher MDASI Interference Score (higher symptom burden) was associated with patients being less likely to have a living will or medical power of attorney (p=0.003). Higher DAS score (increased death anxiety) was associated with patients being less likely to have completed a living will or medical power of attorney (p=0.03). Most patients were familiar with advance directives, but less than half had created these documents. Young age, lower level of education, disease-related interference with daily activities, and a higher level of death anxiety were associated with decreased rates of advance directive completion, indicating these may be barriers to advance care planning documentation. Young patients, less educated patients, patients with increased disease symptom burden, and patients with increased death anxiety should be targeted for advance care planning discussions as they may be less likely to engage in advance care planning. Copyright © 2016. Published by Elsevier Inc.

Room for Improvement: An Examination of Advance Care Planning Documentation among Gynecologic Oncology Patients

PubMed Central

Brown, Alaina J.; Shen, Megan Johnson; Urbauer, Diana; Taylor, Jolyn; Parker, Patricia A.; Carmack, Cindy; Prescott, Lauren; Kowaloe, Elizabeth; Rosemore, Carly; Sun, Charlotte; Ramondetta, Lois; Bodurka, Diane C.

2017-01-01

Objectives The goals of this study were: (1) to evaluate patients’ knowledge regarding advance directives and completion rates of advance directives among gynecologic oncology patients and (2) to examine the association between death anxiety, disease symptom burden, and patient initiation of advance directives. Methods 110 gynecologic cancer patients were surveyed regarding their knowledge and completion of advance directives. Patients also completed the MD Anderson Symptom Inventory (MDASI) scale and Templer’s Death Anxiety Scale (DAS). Descriptive statistics were utilized to examine characteristics of the sample. Fisher’s exact tests and 2-sample t-tests were utilized to examine associations between key variables. Results Most patients were white (76.4%) and had ovarian (46.4%) or uterine cancer (34.6%). Nearly half (47.0%) had recurrent disease. The majority of patients had heard about advance directives (75%). Only 49% had completed a living will or medical power of attorney. Older patients and those with a higher level of education were more likely to have completed an advance directive (p<0.01). Higher MDASI Interference Score (higher symptom burden) was associated with patients being less likely to have a living will or medical power of attorney (p=0.003). Higher DAS score (increased death anxiety) was associated with patients being less likely to have completed a living will or medical power of attorney (p=0.03). Conclusion Most patients were familiar with advance directives, but less than half had created these documents. Young age, lower level of education, disease-related interference with daily activities, and a higher level of death anxiety were associated with decreased rates of advance directive completion, indicating these may be barriers to advance care planning documentation. Young patients, less educated patients, patients with increased disease symptom burden, and patients with increased death anxiety should be targeted for advance care planning discussions as they may be less likely to engage in advance care planning. PMID:27439968

Method of Calculating the Correction Factors for Cable Dimensioning in Smart Grids

NASA Astrophysics Data System (ADS)

Simutkin, M.; Tuzikova, V.; Tlusty, J.; Tulsky, V.; Muller, Z.

2017-04-01

One of the main causes of overloading electrical equipment by currents of higher harmonics is the great increasing of a number of non-linear electricity power consumers. Non-sinusoidal voltages and currents affect the operation of electrical equipment, reducing its lifetime, increases the voltage and power losses in the network, reducing its capacity. There are standards that respects emissions amount of higher harmonics current that cannot provide interference limit for a safe level in power grid. The article presents a method for determining a correction factor to the long-term allowable current of the cable, which allows for this influence. Using mathematical models in the software Elcut, it was described thermal processes in the cable in case the flow of non-sinusoidal current. Developed in the article theoretical principles, methods, mathematical models allow us to calculate the correction factor to account for the effect of higher harmonics in the current spectrum for network equipment in any type of non-linear load.

Advanced development of a programmable power processor

NASA Technical Reports Server (NTRS)

Lukens, F. E.; Lanier, J. R., Jr.; Kapustka, R. E.; Graves, J.

1980-01-01

The need for the development of a multipurpose flexible programmable power processor (PPP) has increased significantly in recent years to reduce ever rising development costs. One of the program requirements the PPP specification will cover is the 25 kW power module power conversion needs. The 25 kW power module could support the Space Shuttle program during the 1980s and 1990s and could be the stepping stone to future large space programs. Trades that led to selection of a microprocessor controlled power processor are briefly discussed. Emphasis is given to the power processing equipment that uses a microprocessor to provide versatility that allows multiple use and to provide for future growth by reprogramming output voltage to a higher level (to 120 V from 30 V). Component selection and design considerations are also discussed.

Prevalence and correlates of young people's sexual aggression perpetration and victimisation in 10 European countries: a multi-level analysis.

PubMed

Krahé, Barbara; Berger, Anja; Vanwesenbeeck, Ine; Bianchi, Gabriel; Chliaoutakis, Joannes; Fernández-Fuertes, Andrés A; Fuertes, Antonio; de Matos, Margarida Gaspar; Hadjigeorgiou, Eleni; Haller, Birgitt; Hellemans, Sabine; Izdebski, Zbigniew; Kouta, Christiana; Meijnckens, Dwayne; Murauskiene, Liubove; Papadakaki, Maria; Ramiro, Lucia; Reis, Marta; Symons, Katrien; Tomaszewska, Paulina; Vicario-Molina, Isabel; Zygadło, Andrzej

2015-01-01

Data are presented on young people's sexual victimisation and perpetration from 10 European countries (Austria, Belgium, Cyprus, Greece, Lithuania, the Netherlands, Poland, Portugal, Slovakia and Spain) using a shared measurement tool (N = 3480 participants, aged between 18 and 27 years). Between 19.7 and 52.2% of female and between 10.1 and 55.8% of male respondents reported having experienced at least one incident of sexual victimisation since the age of consent. In two countries, victimisation rates were significantly higher for men than for women. Between 5.5 and 48.7% of male and 2.6 and 14.8% of female participants reported having engaged in a least one act of sexual aggression perpetration, with higher rates for men than for women in all countries. Victimisation rates correlated negatively with sexual assertiveness and positively with alcohol use in sexual encounters. Perpetration rates correlated positively with attitudes condoning physical dating violence and with alcohol use in men, and negatively with sexual assertiveness in women. At the country level, lower gender equality in economic power and in the work domain was related to higher male perpetration rates. Lower gender equality in political power and higher sexual assertiveness in women relative to men were linked to higher male victimisation rates.

MPD thruster research issues, activities, strategies

NASA Technical Reports Server (NTRS)

1991-01-01

The following activities and plans in the MPD thruster development are summarized: (1) experimental and theoretical research (magnetic nozzles at present and high power levels, MPD thrusters with applied fields extending into the thrust chamber, and improved electrode performance); and (2) tools (MACH2 code for MPD and nozzle flow calculation, laser diagnostics and spectroscopy for non-intrusive measurements of flow conditions, and extension to higher power). National strategies are also outlined.

Development of new sealed bipolar lead-acid battery

NASA Technical Reports Server (NTRS)

Attia, Alan I.; Rowlette, J. J.

1987-01-01

New light weight composite bipolar plates which can withstand the corrosive environment of the lead acid battery have made possible the construction of a sealed bipolar lead acid battery that promises to achieve very high specific power levels and substantially higher energy densities than conventional lead acid batteries. Performance projections based on preliminary experimental results show that the peak specific power of the battery can be as high as 90 kW/kg, and that a specific power of 5 kW/kg can be sustained over several thousand pulses.

The development of a new sealed bipolar lead-acid battery

NASA Technical Reports Server (NTRS)

Attia, A. I.; Rowlette, J. J.

1988-01-01

New light weight composite bipolar plates which can withstand the corrosive environment of the lead acid battery have made possible the construction of a sealed bipolar lead acid battery that promises to achieve very high specific power levels and substantially higher energy densities than conventional lead acid batteries. Performance projections based on preliminary experimental results show that the peak specific power of the battery can be as high as 90 kW/kg, and that a specific power of 5 kW/kg can be sustained over several thousand pulses.

Estimating workload using EEG spectral power and ERPs in the n-back task

NASA Astrophysics Data System (ADS)

Brouwer, Anne-Marie; Hogervorst, Maarten A.; van Erp, Jan B. F.; Heffelaar, Tobias; Zimmerman, Patrick H.; Oostenveld, Robert

2012-08-01

Previous studies indicate that both electroencephalogram (EEG) spectral power (in particular the alpha and theta band) and event-related potentials (ERPs) (in particular the P300) can be used as a measure of mental work or memory load. We compare their ability to estimate workload level in a well-controlled task. In addition, we combine both types of measures in a single classification model to examine whether this results in higher classification accuracy than either one alone. Participants watched a sequence of visually presented letters and indicated whether or not the current letter was the same as the one (n instances) before. Workload was varied by varying n. We developed different classification models using ERP features, frequency power features or a combination (fusion). Training and testing of the models simulated an online workload estimation situation. All our ERP, power and fusion models provide classification accuracies between 80% and 90% when distinguishing between the highest and the lowest workload condition after 2 min. For 32 out of 35 participants, classification was significantly higher than chance level after 2.5 s (or one letter) as estimated by the fusion model. Differences between the models are rather small, though the fusion model performs better than the other models when only short data segments are available for estimating workload.

A Model-Based Approach to Predicting Graduate-Level Performance Using Indicators of Undergraduate-Level Performance

ERIC Educational Resources Information Center

Zimmermann, Judith; Brodersen, Kay H.; Heinimann, Hans R.; Buhmann, Joachim M.

2015-01-01

The graduate admissions process is crucial for controlling the quality of higher education, yet, rules-of-thumb and domain-specific experiences often dominate evidence-based approaches. The goal of the present study is to dissect the predictive power of undergraduate performance indicators and their aggregates. We analyze 81 variables in 171…

Chornobyl, radiation, neural tube defects, and microcephaly.

PubMed

Wertelecki, Wladimir; Yevtushok, Lyubov; Kuznietsov, Illia; Komov, Oleksandr; Lapchenko, Serhii; Akhmedzanova, Diana; Ostapchuk, Lyubov

2018-06-13

Pregnant women residing in areas impacted by the Chornobyl ionizing radiation of the Rivne Province in Ukraine have persistent higher levels of incorporated cesium-137. In these areas the neural tube defects and microcephaly rates are significantly higher than in areas with lower maternal cesium-137 incorporated levels. In two Rivne counties with populations proximal to nuclear power plants the rates of neural tube defects and microcephaly are the highest in the province. The neural tube defects rates in Rivne are persistently among the highest in Europe. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

An Analysis of the Effects of RFID Tags on Narrowband Navigation and Communication Receivers

NASA Technical Reports Server (NTRS)

LaBerge, E. F. Charles

2007-01-01

The simulated effects of the Radio Frequency Identification (RFID) tag emissions on ILS Localizer and ILS Glide Slope functions match the analytical models developed in support of DO-294B provided that the measured peak power levels are adjusted for 1) peak-to-average power ratio, 2) effective duty cycle, and 3) spectrum analyzer measurement bandwidth. When these adjustments are made, simulated and theoretical results are in extraordinarily good agreement. The relationships hold over a large range of potential interference-to-desired signal power ratios, provided that the adjusted interference power is significantly higher than the sum of the receiver noise floor and the noise-like contributions of all other interference sources. When the duty-factor adjusted power spectral densities are applied in the evaluation process described in Section 6 of DO-294B, most narrowband guidance and communications radios performance parameters are unaffected by moderate levels of RFID interference. Specific conclusions and recommendations are provided.

Entropy Based Genetic Association Tests and Gene-Gene Interaction Tests

PubMed Central

de Andrade, Mariza; Wang, Xin

2011-01-01

In the past few years, several entropy-based tests have been proposed for testing either single SNP association or gene-gene interaction. These tests are mainly based on Shannon entropy and have higher statistical power when compared to standard χ2 tests. In this paper, we extend some of these tests using a more generalized entropy definition, Rényi entropy, where Shannon entropy is a special case of order 1. The order λ (>0) of Rényi entropy weights the events (genotype/haplotype) according to their probabilities (frequencies). Higher λ places more emphasis on higher probability events while smaller λ (close to 0) tends to assign weights more equally. Thus, by properly choosing the λ, one can potentially increase the power of the tests or the p-value level of significance. We conducted simulation as well as real data analyses to assess the impact of the order λ and the performance of these generalized tests. The results showed that for dominant model the order 2 test was more powerful and for multiplicative model the order 1 or 2 had similar power. The analyses indicate that the choice of λ depends on the underlying genetic model and Shannon entropy is not necessarily the most powerful entropy measure for constructing genetic association or interaction tests. PMID:23089811

The potential impact of new power system technology on the design of a manned space station

NASA Technical Reports Server (NTRS)

Fordyce, J. S.; Schwartz, H. J.

1984-01-01

Larger, more complex spacecraft of the future such as a manned Space Station will require electric power systems of 100 kW and more, orders of magnitude greater than the present state of the art. Power systems at this level will have a significant impact on the spacecraft design. Historically, long-lived spacecraft have relied on silicon solar cell arrays, a nickel-cadmium storage battery and operation at 28 V dc. These technologies lead to large array areas and heavy batteries for a Space Station application. This, in turn, presents orbit altitude maintenance, attitude control, energy management and launch weight and volume constraints. Size (area) and weight of such a power system can be reduced if new higher efficiency conversion and lighter weight storage technologies are used. Several promising technology options including concentrator solar photovoltaic arrays, solar thermal dynamic and ultimately nuclear dynamic systems to reduce area are discussed. Also, higher energy storage systems such as nickel-hydrogen and the regenerative fuel cell (RFC) and higher voltage power distribution which add system flexibility, simplicity and reduce weight are examined. Emphasis is placed on the attributes and development status of emerging technologies that are sufficiently developed so that they could be available for flight use in the early to mid 1990's.

The potential impact of new power system technology on the design of a manned Space Station

NASA Technical Reports Server (NTRS)

Fordyce, J. S.; Schwartz, H. J.

1984-01-01

Larger, more complex spacecraft of the future such as a manned Space Station will require electric power systems of 100 kW and more, orders of magnitude greater than the present state of the art. Power systems at this level will have a significant impact on the spacecraft design. Historically, long-lived spacecraft have relied on silicon solar cell arrays, a nickel-cadmium storage battery and operation at 28 V dc. These technologies lead to large array areas and heavy batteries for a Space Station application. This, in turn, presents orbit altitude maintenance, attitude control, energy management and launch weight and volume constraints. Size (area) and weight of such a power system can be reduced if new higher efficiency conversion and lighter weight storage technologies are used. Several promising technology options including concentrator solar photovoltaic arrays, solar thermal dynamic and ultimately nuclear dynamic systems to reduce area are discussed. Also, higher energy storage systems such as nickel-hydrogen and the regenerative fuel cell (RFC) and higher voltage power distribution which add system flexibility, simplicity and reduce weight are examined. Emphasis placed on the attributes and development status of emerging technologies that are sufficiently developed so that they could be available for flight use in the early to mid 1990's.

Solar dynamic power system definition study

NASA Technical Reports Server (NTRS)

Wallin, Wayne E.; Friefeld, Jerry M.

1988-01-01

The solar dynamic power system design and analysis study compared Brayton, alkali-metal Rankine, and free-piston Stirling cycles with silicon planar and GaAs concentrator photovoltaic power systems for application to missions beyond the Phase 2 Space Station level of technology for all power systems. Conceptual designs for Brayton and Stirling power systems were developed for 35 kWe and 7 kWe power levels. All power systems were designed for 7-year end-of-life conditions in low Earth orbit. LiF was selected for thermal energy storage for the solar dynamic systems. Results indicate that the Stirling cycle systems have the highest performance (lowest weight and area) followed by the Brayton cycle, with photovoltaic systems considerably lower in performance. For example, based on the performance assumptions used, the planar silicon power system weight was 55 to 75 percent higher than for the Stirling system. A technology program was developed to address areas wherein significant performance improvements could be realized relative to the current state-of-the-art as represented by Space Station. In addition, a preliminary evaluation of hardenability potential found that solar dynamic systems can be hardened beyond the hardness inherent in the conceptual designs of this study.

High source levels and small active space of high-pitched song in bowhead whales (Balaena mysticetus).

PubMed

Tervo, Outi M; Christoffersen, Mads F; Simon, Malene; Miller, Lee A; Jensen, Frants H; Parks, Susan E; Madsen, Peter T

2012-01-01

The low-frequency, powerful vocalizations of blue and fin whales may potentially be detected by conspecifics across entire ocean basins. In contrast, humpback and bowhead whales produce equally powerful, but more complex broadband vocalizations composed of higher frequencies that suffer from higher attenuation. Here we evaluate the active space of high frequency song notes of bowhead whales (Balaena mysticetus) in Western Greenland using measurements of song source levels and ambient noise. Four independent, GPS-synchronized hydrophones were deployed through holes in the ice to localize vocalizing bowhead whales, estimate source levels and measure ambient noise. The song had a mean apparent source level of 185±2 dB rms re 1 µPa @ 1 m and a high mean centroid frequency of 444±48 Hz. Using measured ambient noise levels in the area and Arctic sound spreading models, the estimated active space of these song notes is between 40 and 130 km, an order of magnitude smaller than the estimated active space of low frequency blue and fin whale songs produced at similar source levels and for similar noise conditions. We propose that bowhead whales spatially compensate for their smaller communication range through mating aggregations that co-evolved with broadband song to form a complex and dynamic acoustically mediated sexual display.

High Source Levels and Small Active Space of High-Pitched Song in Bowhead Whales (Balaena mysticetus)

PubMed Central

Tervo, Outi M.; Christoffersen, Mads F.; Simon, Malene; Miller, Lee A.; Jensen, Frants H.; Parks, Susan E.; Madsen, Peter T.

2012-01-01

The low-frequency, powerful vocalizations of blue and fin whales may potentially be detected by conspecifics across entire ocean basins. In contrast, humpback and bowhead whales produce equally powerful, but more complex broadband vocalizations composed of higher frequencies that suffer from higher attenuation. Here we evaluate the active space of high frequency song notes of bowhead whales (Balaena mysticetus) in Western Greenland using measurements of song source levels and ambient noise. Four independent, GPS-synchronized hydrophones were deployed through holes in the ice to localize vocalizing bowhead whales, estimate source levels and measure ambient noise. The song had a mean apparent source level of 185±2 dB rms re 1 µPa @ 1 m and a high mean centroid frequency of 444±48 Hz. Using measured ambient noise levels in the area and Arctic sound spreading models, the estimated active space of these song notes is between 40 and 130 km, an order of magnitude smaller than the estimated active space of low frequency blue and fin whale songs produced at similar source levels and for similar noise conditions. We propose that bowhead whales spatially compensate for their smaller communication range through mating aggregations that co-evolved with broadband song to form a complex and dynamic acoustically mediated sexual display. PMID:23300591

Electromagnetic immunity of implantable pacemakers exposed to wi-fi devices.

PubMed

Mattei, Eugenio; Censi, Federica; Triventi, Michele; Calcagnini, Giovanni

2014-10-01

The purpose of this study is to evaluate the potential for electromagnetic interference (EMI) and to assess the immunity level of implantable pacemakers (PM) when exposed to the radiofrequency (RF) field generated by Wi-Fi devices. Ten PM from five manufacturers, representative of what today is implanted in patients, have been tested in vitro and exposed to the signal generated by a Wi-Fi transmitter. An exposure setup that reproduces the actual IEEE 802.11b/g protocol has been designed and used during the tests. The system is able to amplify the Wi-Fi signal and transmits at power levels higher than those allowed by current international regulation. Such approach allows one to obtain, in case of no EMI, a safety margin for PM exposed to Wi-Fi signals, which otherwise cannot be derived if using commercial Wi-Fi equipment. The results of this study mitigate concerns about using Wi-Fi devices close to PM: none of the PM tested exhibit any degradation of their performance, even when exposed to RF field levels five times higher than those allowed by current international regulation (20 W EIRP). In conclusion, Wi-Fi devices do not pose risks of EMI to implantable PM. The immunity level of modern PM is much higher than the transmitting power of RF devices operating at 2.4 GHz.

Universal Power Law of the Gravity Wave Manifestation in the AIM CIPS Polar Mesospheric Cloud Images

NASA Astrophysics Data System (ADS)

Rong, P. P.; Yue, J.; Russell, J. M., III; Siskind, D. E.; Randall, C. E.

2017-12-01

A large ensemble of gravity waves (GWs) resides in the PMCs and we aim to extract the universal law that governs the wave display throughout the GW population. More specifically, we examined how wave display morphology and clarity level varies throughout the wave population manifested through the PMC albedo data. Higher clarity refers to more distinct exhibition of the features which often correspond to larger variances and better organized nature. A gravity wave tracking algorithm is designed and applied to the PMC albedo data taken by the AIM Cloud Imaging and Particle Size (CIPS) instrument to obtain the gravity wave detections throughout the two northern summers in 2007 and 2010. The horizontal wavelengths in the range of 20-60km are the focus of the study because they are the most commonly observed and readily captured in the CIPS orbital strips. A 1-dimensional continuous wavelet transform (CWT) is applied to PMC albedo along all radial directions within an elliptical region that has a radius of 400 km and an axial ratio of 0.65. The center of the elliptical region moves around the CIPS orbital strips so that waves at different locations and orientations can be captured. It shows that the CWT albedo power statistically increases as the background gets brighter. We resample the wave detections to conform to a normal distribution via removing the dependence of the albedo power on the background cloud brightness because we tend to examine the wave morphology beyond the cloud brightness impact. Sample cases are selected at the two tails and the peak of the normal distribution, and at three brightness levels, to represent the high, medium, and low albedo power categories. For these cases the albedo CWT power spectra follow exponential decay toward smaller scales. The high albedo power has the most rapid decay (i.e., exponent=-3.2) and corresponds to the most distinct wave display. Overall higher albedo power and more rapid decay both contributed to the more distinct display. The wave display becomes increasingly more blurry for the medium and low power categories that hold the exponents of -2.9 and -2.5, respectively. The majority of waves are straight waves whose clarity levels can be collapsed irrespective of the brightness levels but in the brighter background the wave signatures seem to exhibit mildly turbulent-like behavior.

High-Temperature Electronics: A Role for Wide Bandgap Semiconductors?

NASA Technical Reports Server (NTRS)

Neudeck, Philip G.; Okojie, Robert S.; Chen, Liang-Yu

2002-01-01

It is increasingly recognized that semiconductor based electronics that can function at ambient temperatures higher than 150 C without external cooling could greatly benefit a variety of important applications, especially-in the automotive, aerospace, and energy production industries. The fact that wide bandgap semiconductors are capable of electronic functionality at much higher temperatures than silicon has partially fueled their development, particularly in the case of SiC. It appears unlikely that wide bandgap semiconductor devices will find much use in low-power transistor applications until the ambient temperature exceeds approximately 300 C, as commercially available silicon and silicon-on-insulator technologies are already satisfying requirements for digital and analog very large scale integrated circuits in this temperature range. However, practical operation of silicon power devices at ambient temperatures above 200 C appears problematic, as self-heating at higher power levels results in high internal junction temperatures and leakages. Thus, most electronic subsystems that simultaneously require high-temperature and high-power operation will necessarily be realized using wide bandgap devices, once the technology for realizing these devices become sufficiently developed that they become widely available. Technological challenges impeding the realization of beneficial wide bandgap high ambient temperature electronics, including material growth, contacts, and packaging, are briefly discussed.

EEG-MEG Integration Enhances the Characterization of Functional and Effective Connectivity in the Resting State Network

PubMed Central

Mideksa, Kidist Gebremariam; Anwar, Abdul Rauf; Stephani, Ulrich; Deuschl, Günther; Freitag, Christine M.; Siniatchkin, Michael

2015-01-01

At the sensor level many aspects, such as spectral power, functional and effective connectivity as well as relative-power-ratio ratio (RPR) and spatial resolution have been comprehensively investigated through both electroencephalography (EEG) and magnetoencephalography (MEG). Despite this, differences between both modalities have not yet been systematically studied by direct comparison. It remains an open question as to whether the integration of EEG and MEG data would improve the information obtained from the above mentioned parameters. Here, EEG (64-channel system) and MEG (275 sensor system) were recorded simultaneously in conditions with eyes open (EO) and eyes closed (EC) in 29 healthy adults. Spectral power, functional and effective connectivity, RPR, and spatial resolution were analyzed at five different frequency bands (delta, theta, alpha, beta and gamma). Networks of functional and effective connectivity were described using a spatial filter approach called the dynamic imaging of coherent sources (DICS) followed by the renormalized partial directed coherence (RPDC). Absolute mean power at the sensor level was significantly higher in EEG than in MEG data in both EO and EC conditions. At the source level, there was a trend towards a better performance of the combined EEG+MEG analysis compared with separate EEG or MEG analyses for the source mean power, functional correlation, effective connectivity for both EO and EC. The network of coherent sources and the spatial resolution were similar for both the EEG and MEG data if they were analyzed separately. Results indicate that the combined approach has several advantages over the separate analyses of both EEG and MEG. Moreover, by a direct comparison of EEG and MEG, EEG was characterized by significantly higher values in all measured parameters in both sensor and source level. All the above conclusions are specific to the resting state task and the specific analysis used in this study to have general conclusion multi-center studies would be helpful. PMID:26509448

View from... Photonics Meets Biology Summer School: The bio-mission of diode lasers

NASA Astrophysics Data System (ADS)

Won, Rachel

2015-12-01

Diode lasers represent a viable alternative to light sources used in many biomedical applications. Their ongoing development will further increase their importance, offering not only multiple wavelength ranges, but also higher power levels.

An Investigation in the Ames 40- by 80-Foot Wind Tunnel of a YT-56A Turboprop Engine Incorporating a Decoupler and a Controlled-Feathering Device

NASA Technical Reports Server (NTRS)

Rogallo, Vernon L.; Yaggy, Paul F.; McCloud, John L., III

1954-01-01

An investigation of a decoupler and a controlled-feathering device incorporated with the YT-56A turboprop engine has been made to determine the effectiveness of these devices in reducing the high negative thrust (drag) which accompanies power failure of this type of engine. Power failures were simulated by fuel cut-off, both without either device free to operate, and with each device free to operate singly. The investigation was made through an airspeed range from 50 to 230 mph. It was found that with neither device free to operate, the drag levels realized after power failures at airspeeds above 170 mph would impose vertical tail loads higher than those allowable for the YC-130, the airplane for which the test power package was designed. These levels were reached in approximately one second. The maximum drag realized after power failure was not appreciably altered by the use of the decoupler although the decoupler did put a limit on the duration of the peak drag. The controlled-feathering device maintained a level of essentially zero drag after power failure. The use of the decoupler in the YT-56A engine complicates windmilling air-starting procedures and makes it necessary to place operating restrictions on the engine to assure safe flight at low-power conditions,

High Power MPD Thruster Performance Measurements

NASA Technical Reports Server (NTRS)

LaPointe, Michael R.; Strzempkowski, Eugene; Pencil, Eric

2004-01-01

High power magnetoplasmadynamic (MPD) thrusters are being developed as cost effective propulsion systems for cargo transport to lunar and Mars bases, crewed missions to Mars and the outer planets, and robotic deep space exploration missions. Electromagnetic MPD thrusters have demonstrated, at the laboratory level, the ability to process megawatts of electrical power while providing significantly higher thrust densities than electrostatic electric propulsion systems. The ability to generate higher thrust densities permits a reduction in the number of thrusters required to perform a given mission, and alleviates the system complexity associated with multiple thruster arrays. The specific impulse of an MPD thruster can be optimized to meet given mission requirements, from a few thousand seconds with heavier gas propellants up to 10,000 seconds with hydrogen propellant. In support of programs envisioned by the NASA Office of Exploration Systems, Glenn Research Center is developing and testing quasi-steady MW-class MPD thrusters as a prelude to steady state high power thruster tests. This paper provides an overview of the GRC high power pulsed thruster test facility, and presents preliminary performance data for a quasi-steady baseline MPD thruster geometry.

Islanding the power grid on the transmission level: less connections for more security

PubMed Central

Mureddu, Mario; Caldarelli, Guido; Damiano, Alfonso; Scala, Antonio; Meyer-Ortmanns, Hildegard

2016-01-01

Islanding is known as a management procedure of the power system that is implemented at the distribution level to preserve sensible loads from outages and to guarantee the continuity in electricity supply, when a high amount of distributed generation occurs. In this paper we study islanding on the level of the transmission grid and shall show that it is a suitable measure to enhance energy security and grid resilience. We consider the German and Italian transmission grids. We remove links either randomly to mimic random failure events, or according to a topological characteristic, their so-called betweenness centrality, to mimic an intentional attack and test whether the resulting fragments are self-sustainable. We test this option via the tool of optimized DC power flow equations. When transmission lines are removed according to their betweenness centrality, the resulting islands have a higher chance of being dynamically self-sustainable than for a random removal. Less connections may even increase the grid’s stability. These facts should be taken into account in the design of future power grids. PMID:27713509

Scalable waveguide design for three-level operation in Neodymium doped fiber laser

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

Pax, Paul H.; Khitrov, Victor V.; Drachenberg, Derrek R.

We have constructed a double clad neodymium doped fiber laser operating on the three-level 4F 3/2 → 4I 9/2 transition. The laser has produced 11.5 W at 925 nm with 55% slope efficiency when pumped at 808 nm, comparable to the best previous results for a double-clad fiber configuration on this transition. Higher power pumping with both 808 nm and 880 nm sources resulted in an output of 27 W, albeit at lower slope efficiency. In both cases, output power was limited by available pump, indicating the potential for further power scaling. To suppress the stronger four-level 4F 3/2 →more » 4I 11/2 transition we developed a waveguide that provides spectral filtering distributed along the length of the fiber, based on an all-solid micro-structured optical fiber design, with resonant inclusions creating a leakage path to the cladding. Furthermore, the waveguide supports large mode areas and provides strong suppression at selectable wavelength bands, thus easing the restrictions on core and cladding sizes that limited power scaling of previous approaches.« less

Scalable waveguide design for three-level operation in Neodymium doped fiber laser

DOE PAGES

Pax, Paul H.; Khitrov, Victor V.; Drachenberg, Derrek R.; ...

2016-12-12

We have constructed a double clad neodymium doped fiber laser operating on the three-level 4F 3/2 → 4I 9/2 transition. The laser has produced 11.5 W at 925 nm with 55% slope efficiency when pumped at 808 nm, comparable to the best previous results for a double-clad fiber configuration on this transition. Higher power pumping with both 808 nm and 880 nm sources resulted in an output of 27 W, albeit at lower slope efficiency. In both cases, output power was limited by available pump, indicating the potential for further power scaling. To suppress the stronger four-level 4F 3/2 →more » 4I 11/2 transition we developed a waveguide that provides spectral filtering distributed along the length of the fiber, based on an all-solid micro-structured optical fiber design, with resonant inclusions creating a leakage path to the cladding. Furthermore, the waveguide supports large mode areas and provides strong suppression at selectable wavelength bands, thus easing the restrictions on core and cladding sizes that limited power scaling of previous approaches.« less

Multiple high-intensity focused ultrasound probes for kidney-tissue ablation.

PubMed

Häcker, Axel; Chauhan, Sunita; Peters, Kristina; Hildenbrand, Ralf; Marlinghaus, Ernst; Alken, Peter; Michel, Maurice Stephan

2005-10-01

To investigate kidney-tissue ablation by high-intensity focused ultrasound (HIFU) using multiple and single probes. Ultrasound beams (1.75 MHz) produced by a piezoceramic element (focal distance 80 mm) were focused at the center of renal parenchyma. One of the three probes (mounted on a jig) could also be used for comparison with a single probe at comparable power ratings. Lesion dimensions were examined in perfused and unperfused ex vivo porcine kidneys at different power levels (40, 60, and 80 W) and treatment times (4, 6, and 8 seconds). At identical power levels, the lesions induced by multiple probes were larger than those induced by a single probe. Lesion size increased with increasing pulse duration and generator power. The sizes and shapes of the lesions were predictably repeatable in all samples. Lesions in perfused kidneys were smaller than those in unperfused kidneys. Ex vivo, kidney-tissue ablation by means of multiple HIFU probes offers significant advantages over single HIFU probes in respect of lesion size and formation. These advantages need to be confirmed by tests in vivo at higher energy levels.

Islanding the power grid on the transmission level: less connections for more security

NASA Astrophysics Data System (ADS)

Mureddu, Mario; Caldarelli, Guido; Damiano, Alfonso; Scala, Antonio; Meyer-Ortmanns, Hildegard

2016-10-01

Islanding is known as a management procedure of the power system that is implemented at the distribution level to preserve sensible loads from outages and to guarantee the continuity in electricity supply, when a high amount of distributed generation occurs. In this paper we study islanding on the level of the transmission grid and shall show that it is a suitable measure to enhance energy security and grid resilience. We consider the German and Italian transmission grids. We remove links either randomly to mimic random failure events, or according to a topological characteristic, their so-called betweenness centrality, to mimic an intentional attack and test whether the resulting fragments are self-sustainable. We test this option via the tool of optimized DC power flow equations. When transmission lines are removed according to their betweenness centrality, the resulting islands have a higher chance of being dynamically self-sustainable than for a random removal. Less connections may even increase the grid’s stability. These facts should be taken into account in the design of future power grids.

Black-boxing and cause-effect power

PubMed Central

Albantakis, Larissa; Tononi, Giulio

2018-01-01

Reductionism assumes that causation in the physical world occurs at the micro level, excluding the emergence of macro-level causation. We challenge this reductionist assumption by employing a principled, well-defined measure of intrinsic cause-effect power–integrated information (Φ), and showing that, according to this measure, it is possible for a macro level to “beat” the micro level. Simple systems were evaluated for Φ across different spatial and temporal scales by systematically considering all possible black boxes. These are macro elements that consist of one or more micro elements over one or more micro updates. Cause-effect power was evaluated based on the inputs and outputs of the black boxes, ignoring the internal micro elements that support their input-output function. We show how black-box elements can have more common inputs and outputs than the corresponding micro elements, revealing the emergence of high-order mechanisms and joint constraints that are not apparent at the micro level. As a consequence, a macro, black-box system can have higher Φ than its micro constituents by having more mechanisms (higher composition) that are more interconnected (higher integration). We also show that, for a given micro system, one can identify local maxima of Φ across several spatiotemporal scales. The framework is demonstrated on a simple biological system, the Boolean network model of the fission-yeast cell-cycle, for which we identify stable local maxima during the course of its simulated biological function. These local maxima correspond to macro levels of organization at which emergent cause-effect properties of physical systems come into focus, and provide a natural vantage point for scientific inquiries. PMID:29684020

ENGINEERING AND CONSTRUCTING THE HALLAM NUCLEAR POWER FACILITY REACTOR STRUCTURE

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

Mahlmeister, J E; Haberer, W V; Casey, D F

1960-12-15

The Hallam Nuclear Power Facility reactor structure, including the cavity liner, is described, and the design philosophy and special design requirements which were developed during the preliminary and final engineering phases of the project are explained. The structure was designed for 600 deg F inlet and 1000 deg F outlet operating sodium temperatures and fabricated of austenitic and ferritic stainless steels. Support for the reactor core components and adequate containment for biological safeguards were readily provided even though quite conservative design philosophy was used. The calculated operating characteristics, including heat generation, temperature distributions and stress levels for full-power operation, aremore » summarized. Ship fabrication and field installation experiences are also briefly related. Results of this project have established that the sodium graphite reactor permits practical and economical fabrication and field erection procedures; considerably higher operating design temperatures are believed possible without radical design changes. Also, larger reactor structures can be similarly constructed for higher capacity (300 to 1000 Mwe) nuclear power plants. (auth)« less

Pyrolysis of tyre powder using microwave thermogravimetric analysis: Effect of microwave power.

PubMed

Song, Zhanlong; Yang, Yaqing; Zhou, Long; Zhao, Xiqiang; Wang, Wenlong; Mao, Yanpeng; Ma, Chunyuan

2017-02-01

The pyrolytic characteristics of tyre powder treated under different microwave powers (300, 500, and 700 W) were studied via microwave thermogravimetric analysis. The product yields at different power levels were studied, along with comparative analysis of microwave pyrolysis and conventional pyrolysis. The feedstock underwent preheating, intense pyrolysis, and final pyrolysis in sequence. The main and secondary weight loss peaks observed during the intense pyrolysis stage were attributed to the decomposition of natural rubbers and synthetic rubbers, respectively. The total mass loss rates, bulk temperatures, and maximum temperatures were distinctively higher at higher powers. However, the maximum mass loss rate (0.005 s -1 ), the highest yields of liquid product (53%), and the minimum yields of residual solid samples (43.83%) were obtained at 500 W. Compared with conventional pyrolysis, microwave pyrolysis exhibited significantly different behaviour with faster reaction rates, which can decrease the decomposition temperatures of both natural and synthetic rubber by approximately 110 °C-140 °C.

Way-Scaling to Reduce Power of Cache with Delay Variation

NASA Astrophysics Data System (ADS)

Goudarzi, Maziar; Matsumura, Tadayuki; Ishihara, Tohru

The share of leakage in cache power consumption increases with technology scaling. Choosing a higher threshold voltage (Vth) and/or gate-oxide thickness (Tox) for cache transistors improves leakage, but impacts cell delay. We show that due to uncorrelated random within-die delay variation, only some (not all) of cells actually violate the cache delay after the above change. We propose to add a spare cache way to replace delay-violating cache-lines separately in each cache-set. By SPICE and gate-level simulations in a commercial 90nm process, we show that choosing higher Vth, Tox and adding one spare way to a 4-way 16KB cache reduces leakage power by 42%, which depending on the share of leakage in total cache power, gives up to 22.59% and 41.37% reduction of total energy respectively in L1 instruction- and L2 unified-cache with a negligible delay penalty, but without sacrificing cache capacity or timing-yield.

A passive dual-circulator based transmit/receive switch for use with reflection resonators in pulse EPR

PubMed Central

Subramanian, V. S.; Epel, Boris; Mailer, Colin; Halpern, Howard J.

2009-01-01

In order to protect the low noise amplifier (LNA) in the receive arm of a pulsed 250 MHz EPR bridge, it is necessary to install as much isolation as possible between the power exciting the spin system and the LNA when high power is present in the receive arm of the bridge, while allowing the voltage induced by the magnetization in the spin sample to be passed undistorted and undiminished to the LNA once power is reduced below the level that can cause a LNA damage. We discuss a combination of techniques to accomplish this involving the power-routing circulator in the bridge, a second circulator acting as an isolator with passive shunt PIN diodes immediately following the second circulator. The low resistance of the forward biased PIN diode passively generates an impedance mismatch at the second circulator output port during the high power excitation pulse and resonator ring down. The mismatch reflects the high power to the remaining port of the second circulator, dumping it into a system impedance matched load. Only when the power diminishes below the diode conduction threshold will the resistance of the PIN diode rise to a value much higher than the system impedance. This brings the device into conduction mode. We find that the present design passively limits the output power to 14 dBm independent of the input power. For high input power levels the isolation may exceed 60 dB. This level of isolation is sufficient to fully protect the LNA of pulse EPR bridge. PMID:20052312

Satellite power systems (SPS) concept definition study. Volume 2, part 1: System engineering

NASA Technical Reports Server (NTRS)

Hanley, G. M.

1980-01-01

Top level trade studies are presented, including comparison of solid state and klystron concepts, higher concentration on the solar cells, composite and aluminum structure, and several variations to the reference concept. Detailed trade studies are presented in each of the subsystem areas (solar array, power distribution, structures, thermal control, attitude control and stationkeeping, microwave transmission, and ground receiving station). A description of the selected point design is also presented.

Injected Water Augments Cooling In Turboshaft Engine

NASA Technical Reports Server (NTRS)

Biesiadny, Thomas J.; Berger, Brett; Klann, Gary A.; Clark, David A.

1989-01-01

Report describes experiments in which water injected into compressor-bleed cooling air of aircraft turboshaft engine. Injection of water previously suggested as way to provide additional cooling needed to sustain operation at power levels higher than usual. Involves turbine-inlet temperatures high enough to shorten lives of first-stage high-pressure turbine blades. Latent heat of vaporization of injected water serves as additional heat sink to maintain blades at design operating temperatures during high-power operation.

Principles for system level electrochemistry

NASA Technical Reports Server (NTRS)

Thaller, L. H.

1986-01-01

The higher power and higher voltage levels anticipated for future space missions have required a careful review of the techniques currently in use to preclude battery problems that are related to the dispersion characteristics of the individual cells. Not only are the out-of-balance problems accentuated in these larger systems, but the thermal management considerations also require a greater degree of accurate design. Newer concepts which employ active cooling techniques are being developed which permit higher rates of discharge and tighter packing densities for the electrochemical components. This paper will put forward six semi-independent principles relating to battery systems. These principles will progressively address cell, battery and finally system related aspects of large electrochemical storage systems.

Concentrated solar power plants impact on PV penetration level and grid flexibility under Egyptian climate

NASA Astrophysics Data System (ADS)

Moukhtar, Ibrahim; Elbaset, Adel A.; El Dein, Adel Z.; Qudaih, Yaser; Mitani, Yasunori

2018-05-01

Photovoltaic (PV) system integration in the electric grid has been increasing over the past decades. However, the impact of PV penetration on the electric grid, especially during the periods of higher and lower generation for the solar system at the middle of the day and during cloudy weather or at night respectively, limit the high penetration of solar PV system. In this research, a Concentrated Solar Power (CSP) with Thermal Energy Storage (TES) has been aggregated with PV system in order to accommodate the required electrical power during the higher and lower solar energy at all timescales. This paper analyzes the impacts of CSP on the grid-connected PV considering high penetration of PV system, particularly when no energy storages in the form of batteries are used. Two cases have been studied, the first when only PV system is integrated into the electric grid and the second when two types of solar energy (PV and CSP) are integrated. The System Advisor Model (SAM) software is used to simulate the output power of renewable energy. Simulation results show that the performance of CSP has a great impact on the penetration level of PV system and on the flexibility of the electric grid. The overall grid flexibility increases due to the ability of CSP to store and dispatch the generated power. In addition, CSP/TES itself has inherent flexibility. Therefore, CSP reduces the minimum generation constraint of the conventional generators that allows more penetration of the PV system.

High-speed and low-power repeater for VLSI interconnects

NASA Astrophysics Data System (ADS)

Karthikeyan, A.; Mallick, P. S.

2017-10-01

This paper proposes a repeater for boosting the speed of interconnects with low power dissipation. We have designed and implemented at 45 and 32 nm technology nodes. Delay and power dissipation performances are analyzed for various voltage levels at these technology nodes using Spice simulations. A significant reduction in delay and power dissipation are observed compared to a conventional repeater. The results show that the proposed high-speed low-power repeater has a reduced delay for higher load capacitance. The proposed repeater is also compared with LPTG CMOS repeater, and the results shows that the proposed repeater has reduced delay. The proposed repeater can be suitable for high-speed global interconnects and has the capacity to drive large loads.

An investigation of the maximum penetration level of a photovoltaic (PV) system into a traditional distribution grid

NASA Astrophysics Data System (ADS)

Chalise, Santosh

Although solar photovoltaic (PV) systems have remained the fastest growing renewable power generating technology, variability as well as uncertainty in the output of PV plants is a significant issue. This rapid increase in PV grid-connected generation presents not only progress in clean energy but also challenges in integration with traditional electric power grids which were designed for transmission and distribution of power from central stations. Unlike conventional electric generators, PV panels do not have rotating parts and thus have no inertia. This potentially causes a problem when the solar irradiance incident upon a PV plant changes suddenly, for example, when scattered clouds pass quickly overhead. The output power of the PV plant may fluctuate nearly as rapidly as the incident irradiance. These rapid power output fluctuations may then cause voltage fluctuations, frequency fluctuations, and power quality issues. These power quality issues are more severe with increasing PV plant power output. This limits the maximum power output allowed from interconnected PV plants. Voltage regulation of a distribution system, a focus of this research, is a prime limiting factor in PV penetration levels. The IEEE 13-node test feeder, modeled and tested in the MATLAB/Simulink environment, was used as an example distribution feeder to analyze the maximum acceptable penetration of a PV plant. The effect of the PV plant's location was investigated, along with the addition of a VAR compensating device (a D-STATCOM in this case). The results were used to develop simple guidelines for determining an initial estimate of the maximum PV penetration level on a distribution feeder. For example, when no compensating devices are added to the system, a higher level of PV penetration is generally achieved by installing the PV plant close to the substation. The opposite is true when a VAR compensator is installed with the PV plant. In these cases, PV penetration levels over 50% may be safely achieved.

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

Paudel, Nava Raj, E-mail: nrpaudel@yahoo.com; Shvydka, Diana; Parsai, E. Ishmael

Purpose: Gold nanoparticles (GNPs) are known to be effective mediators in microwave hyperthermia. Interaction with an electromagnetic field, large surface to volume ratio, and size quantization of nanoparticles (NPs) can lead to increased cell killing beyond pure heating effects. The purpose of this study is to explore the possibility of free radical generation by GNPs in aqueous media when they are exposed to a microwave field. Methods: A number of samples with 500 mM 5,5-dimethyl-1-pyrroline N-oxide (DMPO) in 20 ppm GNP colloidal suspensions were scanned with an electron paramagnetic resonance (EPR)/electron spin resonance spectrometer to generate and detect free radicals.more » A fixed (9.68 GHz) frequency microwave from the spectrometer has served for both generation and detection of radicals. EPR spectra obtained as first derivatives of intensity with the spectrometer were double integrated to get the free radical signal intensities. Power dependence of radical intensity was studied by applying various levels of microwave power (12.5, 49.7, and 125 mW) while keeping all other scan parameters the same. Free radical signal intensities from initial and final scans, acquired at the same power levels, were compared. Results: Hydroxyl radical (OH⋅) signal was found to be generated due to the exposure of GNP–DMPO colloidal samples to a microwave field. Intensity of OH⋅ signal thus generated at 12.5 mW microwave power for 2.8 min was close to the intensity of OH⋅ signal obtained from a water–DMPO sample exposed to 1.5 Gy ionizing radiation dose. For repeated scans, higher OH⋅ intensities were observed in the final scan for higher power levels applied between the initial and the final scans. Final intensities were higher also for a shorter time interval between the initial and the final scans. Conclusions: Our results observed for the first time demonstrate that GNPs generate OH⋅ radicals in aqueous media when they are exposed to a microwave field. If OH⋅ radicals can be generated close to deoxyribonucleic acid of cells by proper localization of NPs, NP-aided microwave hyperthermia can yield cell killing via both elevated temperature and free radical generation.« less

A novel property of gold nanoparticles: Free radical generation under microwave irradiation.

PubMed

Paudel, Nava Raj; Shvydka, Diana; Parsai, E Ishmael

2016-04-01

Gold nanoparticles (GNPs) are known to be effective mediators in microwave hyperthermia. Interaction with an electromagnetic field, large surface to volume ratio, and size quantization of nanoparticles (NPs) can lead to increased cell killing beyond pure heating effects. The purpose of this study is to explore the possibility of free radical generation by GNPs in aqueous media when they are exposed to a microwave field. A number of samples with 500 mM 5,5-dimethyl-1-pyrroline N-oxide (DMPO) in 20 ppm GNP colloidal suspensions were scanned with an electron paramagnetic resonance (EPR)/electron spin resonance spectrometer to generate and detect free radicals. A fixed (9.68 GHz) frequency microwave from the spectrometer has served for both generation and detection of radicals. EPR spectra obtained as first derivatives of intensity with the spectrometer were double integrated to get the free radical signal intensities. Power dependence of radical intensity was studied by applying various levels of microwave power (12.5, 49.7, and 125 mW) while keeping all other scan parameters the same. Free radical signal intensities from initial and final scans, acquired at the same power levels, were compared. Hydroxyl radical (OH⋅) signal was found to be generated due to the exposure of GNP-DMPO colloidal samples to a microwave field. Intensity of OH⋅ signal thus generated at 12.5 mW microwave power for 2.8 min was close to the intensity of OH⋅ signal obtained from a water-DMPO sample exposed to 1.5 Gy ionizing radiation dose. For repeated scans, higher OH⋅ intensities were observed in the final scan for higher power levels applied between the initial and the final scans. Final intensities were higher also for a shorter time interval between the initial and the final scans. Our results observed for the first time demonstrate that GNPs generate OH⋅ radicals in aqueous media when they are exposed to a microwave field. If OH⋅ radicals can be generated close to deoxyribonucleic acid of cells by proper localization of NPs, NP-aided microwave hyperthermia can yield cell killing via both elevated temperature and free radical generation.

Power optimization of digital baseband WCDMA receiver components on algorithmic and architectural level

NASA Astrophysics Data System (ADS)

Schämann, M.; Bücker, M.; Hessel, S.; Langmann, U.

2008-05-01

High data rates combined with high mobility represent a challenge for the design of cellular devices. Advanced algorithms are required which result in higher complexity, more chip area and increased power consumption. However, this contrasts to the limited power supply of mobile devices. This presentation discusses the application of an HSDPA receiver which has been optimized regarding power consumption with the focus on the algorithmic and architectural level. On algorithmic level the Rake combiner, Prefilter-Rake equalizer and MMSE equalizer are compared regarding their BER performance. Both equalizer approaches provide a significant increase of performance for high data rates compared to the Rake combiner which is commonly used for lower data rates. For both equalizer approaches several adaptive algorithms are available which differ in complexity and convergence properties. To identify the algorithm which achieves the required performance with the lowest power consumption the algorithms have been investigated using SystemC models regarding their performance and arithmetic complexity. Additionally, for the Prefilter Rake equalizer the power estimations of a modified Griffith (LMS) and a Levinson (RLS) algorithm have been compared with the tool ORINOCO supplied by ChipVision. The accuracy of this tool has been verified with a scalable architecture of the UMTS channel estimation described both in SystemC and VHDL targeting a 130 nm CMOS standard cell library. An architecture combining all three approaches combined with an adaptive control unit is presented. The control unit monitors the current condition of the propagation channel and adjusts parameters for the receiver like filter size and oversampling ratio to minimize the power consumption while maintaining the required performance. The optimization strategies result in a reduction of the number of arithmetic operations up to 70% for single components which leads to an estimated power reduction of up to 40% while the BER performance is not affected. This work utilizes SystemC and ORINOCO for the first estimation of power consumption in an early step of the design flow. Thereby algorithms can be compared in different operating modes including the effects of control units. Here an algorithm having higher peak complexity and power consumption but providing more flexibility showed less consumption for normal operating modes compared to the algorithm which is optimized for peak performance.

The effect of p-doping on multi-state lasing in InAs/InGaAs quantum dot lasers for different cavity lengths

NASA Astrophysics Data System (ADS)

Korenev, V. V.; Savelyev, A. V.; Maximov, M. V.; Zubov, F. I.; Shernyakov, Yu M.; Zhukov, A. E.

2017-11-01

The effect of modulation p-doping on multi-state lasing in InAs/InGaAs quantum dot (QD) lasers is studied for different levels of acceptor concentration. It is shown that in case of the short laser cavities, p-doping results in higher output power of the ground-state optical transitions of InAs/InGaAs QDs whereas in longer samples p-doping may result in the decrease of this power component. On the basis of this observation, the optimal design of laser active region and optimal doping level are discussed in details.

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

Baek, M. H.; Kim, S. J.; Yoo, J.

The major roles of a prototype SFR are to provide irradiation test capability for the fuel and structure materials, and to obtain operational experiences of systems. Due to a compromise between the irradiation capability and construction costs, the power level should be properly determined. In this paper, a trade-off study on the power level of the prototype SFR was performed from a neutronics viewpoint. To select candidate cores, the parametric study of pin diameters was estimated using 20 wt.% uranium fuel. The candidate cores of different power levels, 125 MWt, 250 MWt, 400 MWt, and 500 MWt, were compared withmore » the 1500 MWt reference core. The resulting core performance and economic efficiency indices became insensitive to the power at about 400-500 MWt and sharply deteriorated at about 125-250 MWt with decreasing core sizes. Fuel management scheme, TRU core performance comparing with uranium core, and sodium void reactivity were also evaluated with increasing power levels. It is found that increasing the number of batches showed higher burnup performance and economic efficiency. However, increasing the cycle length showed the trends in lower economic efficiency. Irradiation performance of TRU and enriched TRU cores was improved about 20 % and 50 %, respectively. The maximum sodium void reactivity of 5.2$ was confirmed less than the design limit of 7.5$. As a result, the power capacity of the prototype SFR should not be less than 250 MWt and would be appropriate at {approx} 500 MWt considering the performance and economic efficiency. (authors)« less

Association Between Neuromuscular Tests and Kumite Performance on The Brazilian Karate National Team

PubMed Central

Roschel, Hamilton; Batista, Mauro; Monteiro, Rodrigo; Bertuzzi, Romulo C.; Barroso, Renato; Loturco, Irineu; Ugrinowitsch, Carlos; Tricoli, Valmor; Franchini, Emerson

2009-01-01

The aim of this study was to verify the relationship of strength and power with performance on an international level karate team during official kumite simulations. Fourteen male black belt karate athletes were submitted to anthropometric data collection and then performed the following tests on two different days: vertical jump test, bench press and squat maximum dynamic strength (1RM) tests. We also tested power production for both exercises at 30 and 60%1RM and performed a kumite match simulation. Blood samples were obtained at rest and immediately after the kumite matches to measure blood lactate concentration. Karate players were separated by performance (winners vs. defeated) on the kumite matches. We found no significant differences between winners and defeated for strength, vertical jump height, anthropometric data and blood lactate concentration. Interestingly, winners were more powerful in the bench press and squat exercises at 30% 1RM. Maximum strength was correlated with absolute (30% 1RM r = 0.92; 60% 1RM r = 0.63) and relative power (30% 1RM r = 0.74; 60% 1RM r = 0.11, p > 0.05) for the bench press exercise. We concluded that international level karate players’ kumite match performance are influenced by higher levels of upper and lower limbs power production. Key Points Muscle power at low workloads seems to be a reasonable predictor of karate performance. There are differences in neuromuscular characteristics between winners and defeated karate players among an international level karate team. Karate players rely more on muscle power, rather than on muscle strength. PMID:24474882

Promoting self-exploration and function through an individualized power mobility training program.

PubMed

Kenyon, Lisa K; Farris, John; Brockway, Kaelee; Hannum, Nanette; Proctor, Kevin

2015-01-01

This case report describes the development and implementation of an intervention program that used a Power Wheelchair Trainer (Trainer) to enable an individual with severe impairments to participate in power mobility training. The participant was an 18 year-old female with spastic quadriplegic cerebral palsy, Gross Motor Function Classification Level V. The examination included the Power Mobility Screen and the Caregiver Priorities & Child Health Index of Life with Disabilities (CPCHILD). Switches on the participant's headrest provided control of the Trainer. Intervention consisted of power mobility training in an engaging environment that was set-up to focus on specific power mobility skills. Scores on the Power Mobility Screen and the CPCHILD were higher after intervention. The outcomes of this case report appear to support the use of the Trainer, which allowed the participant to practice power mobility skills and participate in self-exploration of her environment.

Alcohol consumption and social inequality at the individual and country levels--results from an international study.

PubMed

Grittner, Ulrike; Kuntsche, Sandra; Gmel, Gerhard; Bloomfield, Kim

2013-04-01

International comparisons of social inequalities in alcohol use have not been extensively investigated. The purpose of this study was to examine the relationship of country-level characteristics and individual socio-economic status (SES) on individual alcohol consumption in 33 countries. Data on 101,525 men and women collected by cross-sectional surveys in 33 countries of the GENACIS study were used. Individual SES was measured by highest attained educational level. Alcohol use measures included drinking status and monthly risky single occasion drinking (RSOD). The relationship between individuals' education and drinking indicators was examined by meta-analysis. In a second step the individual level data and country data were combined and tested in multilevel models. As country level indicators we used the Purchasing Power Parity of the gross national income, the Gini coefficient and the Gender Gap Index. For both genders and all countries higher individual SES was positively associated with drinking status. Also higher country level SES was associated with higher proportions of drinkers. Lower SES was associated with RSOD among men. Women of higher SES in low income countries were more often RSO drinkers than women of lower SES. The opposite was true in higher income countries. For the most part, findings regarding SES and drinking in higher income countries were as expected. However, women of higher SES in low and middle income countries appear at higher risk of engaging in RSOD. This finding should be kept in mind when developing new policy and prevention initiatives.

Thermionic fast spectrum reactor-converter on the basis of multi-cell TFE

NASA Astrophysics Data System (ADS)

Ponomarev-Stepnoi, N. N.; Kompaniets, G. V.; Poliakov, D. N.; Stepennov, B. S.; Andreev, P. V.; Zhabotinsky, E. E.; Nikolaev, Yu. V.; Lapochkin, N. V.

2001-02-01

Today Russian experts have technological experience in development of in-core thermionic converters for reactors of space nuclear power plants. Such a converter contains nuclear fuel inside and really represents a fuel element of a reactor. Two types of reactors can be considered on the basis of these thermionic fuel elements: with thermal or intermediate neutron spectrum, and with fast neutron spectrum. The first type is characterized by the presence of moderator in core that ensures most economical usage of nuclear fuel. The estimation shows that moderated system is the most effective in the power range of about 5 ... 100 kWe. The power systems of higher level are characterized by larger dimensions due to the presence of moderator. The second type of reactor is considered for higher power levels. This power range is about hundreds kWe. Dimensions of the fast reactor and core configuration are determined by the necessity to ensure the required net output power, on the one hand, and the necessity to ensure critical state on the other hand. In the case of using in-core thermionic fuel elements of the specified design, minimal reactor output power is determined by reactor criticality condition, and maximum reactor power output is determined by specifications and launcher capabilities. In the present paper the effective multiplication factor of a fast spectrum reactor on the basis of a multi-cell TFE developed by ``Lutch'' is considered a function of the total number of TFEs in the reactor. The MCU Monte-Carlo code, developed in Russia (Alekseev, et al., 1991), was used for computations. TFE computational models are placed in the nodes of a uniform triangular lattice and surrounded with pressure vessel and a side reflector. Ordinary fuel pins without thermionic converters were used instead of some TFEs to optimize criticality parameters, dimensions and output power of the reactor. General weight parameters of the reactor are presented in the paper. .

What Do Animal Studies Tell Us about the Mechanism of Myopia-Protection by Light?

PubMed

Norton, Thomas T

2016-09-01

: Human studies have provided strong evidence that exposure to time outdoors is protective against the onset of myopia. A causal factor may be that the light levels outdoors (30,000-130,000 lux) are much higher than light levels indoors (typically less than 500 lux). Studies using animal models have found that normal animals exposed to low illuminance levels (50 lux) can develop myopia. The myopia and axial elongation, produced in animals by monocular form deprivation, is reduced by light levels in the 15,000 to 25,000 range. Myopia induced with a negative-power lens seems less affected, perhaps because the lens provides a powerful target for the emmetropization mechanism. Animal studies suggest that raising the light levels may have their effect by increasing retinal dopamine activity, probably via the D2 receptor pathway, altering gene expression in the retina and reducing the signals that produce axial elongation.

[The epidemiological characteristics and correlated factors of daily hassles for thermal power plant workers].

PubMed

Wu, Hui; Yu, Shan-fa; Zhou, Wen-hui; Gu, Gui-zhen

2012-07-01

This study aimed to investigate the epidemiological characteristics and correlated factors of daily hassles among thermal power plant workers. A mass screening of daily hassles and correlated factors was conducted on 498 workers from a thermal power plant in Zhengzhou in July, 2008. The questionnaires included Daily Hassles Questionnaires, Work Roles Questionnaires, Job Content Questionnaires (Chinese version), Effort-Reward Imbalance (Chinese version), Work Locus of Control Scale and Type A Behavior Scale, with content covering demographic characters and occupational stress correlated factors among subjects. The daily hassles was divided into lower level and higher level according to scores, and the epidemiological characteristics and correlated factors of daily hassles were analyzed. A total of 446 qualified questionnaires were obtained, effective response rate was 89.6% (446/498). For respondents, the age was (36.96 ± 6.49) years old, working length of the current job was (12.05 ± 7.54) years, the daily hassles scores was (9.01 ± 2.50), and the prevalence rate of the higher level of daily hassles was 34.1% (152/446). The multiple non-conditional logistic regression analysis showed 5-14 years' working length of current job (OR = 0.451, 95%CI: 0.225 - 0.904), average income > 3000 yuan(OR = 0.372, 95%CI: 0.202 - 0.684), reward (OR = 0.557, 95%CI: 0.325 - 0.954) and coping strategy (OR = 0.552, 95%CI: 0.330 - 0.925) were negatively correlated with daily hassles, and shift-work (OR = 1.887, 95%CI: 1.108 - 3.215), effort (OR = 2.053, 95%CI: 1.198 - 3.519), psychological demand (OR = 1.797, 95%CI: 1.049 - 3.078), negative affectivity (OR = 3.421, 95%CI: 2.065 - 5.668) were positively correlated with daily hassles. The prevalence rate of the higher level of daily hassles was considerable high for thermal power plant workers. Its negative correlated factors included 5 - 14 years' working length of the current job, average income > 3000 yuan, reward and coping strategy and its positive corelated factors included shift-work, effort, psychological demand and negative affectivity.

Towards a Determination of the Physiological Characteristics Distinguishing Successful Mixed Martial Arts Athletes: A Systematic Review of Combat Sport Literature.

PubMed

James, Lachlan P; Haff, G Gregory; Kelly, Vincent G; Beckman, Emma M

2016-10-01

Mixed martial arts (MMA) is a combat sport underpinned by techniques from other combat disciplines, in addition to strategies unique to the sport itself. These sports can be divided into two distinct categories (grappling or striking) based on differing technical demands. Uniquely, MMA combines both methods of combat and therefore appears to be physiologically complex requiring a spectrum of mechanical and metabolic qualities to drive performance. However, little is known about the physiological characteristics that distinguish higher- from lower-level MMA athletes. Such information provides guidance for training interventions, performance testing and talent identification. Furthermore, while MMA incorporates techniques from both grappling and striking sports, it is unknown precisely how these disciplines differ physiologically. Understanding the relationship between higher-level competitors in grappling and striking combat sports can provide further insight into the development of the optimal performance profile of a higher-level MMA athlete. This article aims to analyse the scientific literature on MMA and the primary combat sports underpinning it to determine the physiological adaptations that distinguish superior competitors, with a view to defining the optimal physiological profile for higher-level MMA performance. Furthermore, this article will explore the differences in these capabilities between grappling- and striking-based combat sports in the context of MMA. A literature search was undertaken via PubMed, Web of Science, SportDiscus and Google Scholar. The following sports were included for systematic review based on their relevance to MMA: mixed martial arts, boxing, Brazilian jiu-jitsu, judo, karate, kickboxing, Muay Thai and wrestling. The inclusion criteria allowed studies that compared athletes of differing competition levels in the same sport using a physiological performance measure. Only male, adult (aged 17-40 years), able-bodied competitors were included. The search history spanned from the earliest record until September 2015. Of the eight combat sports searched for, five were represented across 23 studies. Sixteen investigations described maximal strength or neuromuscular power variables, while 19 articles reported anaerobic or aerobic measures. The results indicate that a number of strength, neuromuscular power and anaerobic variables distinguished higher- from lower-level combat sport athletes. However, these differences were less clear when groups were stratified within, rather than between competition grades. Greater aerobic power was generally not present amongst superior combat sport competitors. There appear to be differing physiological profiles between more successful grappling and striking combat sport athletes. This is represented by high-force demands of grappling sports causing an upwards shift of the entire force-velocity relationship driven by an increase in maximal strength. In comparison, smaller increases in maximal force production with more notable enhancements in lighter load, higher velocity actions may better identify superior performance in striking sports. Anaerobic capabilities largely distinguished higher- from lower-level combat sport athletes. In particular, longer-term anaerobic efforts seem to define successful grappling-based athletes, while superior competitors in striking sports tend to show dominance in shorter-term measures when compared with their lower-level counterparts. Given the demand for both forms of combat in MMA, a spectrum of physiological markers may characterize higher-level competitors. Furthermore, the performance profile of successful MMA athletes may differ based on combat sport history or competition strategy.

Bioaccumulation, oxidative stress and genotoxicity in fish (Channa punctatus) exposed to a thermal power plant effluent.

PubMed

Javed, Mehjbeen; Ahmad, Irshad; Usmani, Nazura; Ahmad, Masood

2016-05-01

Metal bioaccumulation and induction of biomarkers such as lipid peroxidation (LPO), superoxide dismutase (SOD), catalase (CAT), glutathione S transferase (GST), reduced glutathione (GSH) and DNA damage are potential indicators of stress in Channa punctatus exposed to effluents. In canal water, receiving thermal power plant discharges, Fe and Ni concentrations exceeded the recommended guidelines set by the United Nations Environment Programme Global Environment Monitoring System (UNEPGEMS). Fe was highly bioavailable and accumulated in all organs (liver, kidney, muscle and integument). The highest metal pollution index (MPI) value of 41.2 was observed in kidney and the lowest 13.5 in muscle tissue. LPO, SOD, CAT and GST levels were significantly higher in liver and kidney, whereas GSH levels declined significantly compared to fish from the reference site. Concomitant damage to DNA was observed with significantly higher mean tail length in the exposed fish gill cells (26.5µm) and in liver (20.8µm) compared to reference fish. Therefore, it can be concluded that the thermal power plant effluent had the potential to cause oxidative stress and DNA damage in C. punctatus. Copyright © 2016 Elsevier Inc. All rights reserved.

Enhancement of water removing and the quality of fried purple-fleshed sweet potato in the vacuum frying by combined power ultrasound and microwave technology.

PubMed

Su, Ya; Zhang, Min; Bhandari, Bhesh; Zhang, Weiming

2018-06-01

The combination of ultrasound and microwave in vacuum frying system was investigated to achieve higher drying efficiency and quality attributes of fried products. Purple-fleshed potato were used as test specimen and different power levels of microwave (0 W, 600 W, 800 W) and ultrasound (0 W, 300 W, 600 W) during vacuum frying. Drying kinetics, dielectric properties, moisture state variation and quality attributes of fried samples were measured in a vacuum frying (VF), and an innovatively designed ultrasound and microwave assisted vacuum frying (USMVF) equipment. The USMVF process markedly increased the moisture evaporation rate and effective moisture diffusivity compared to VF process. The oil uptake was reduced by about 16-34%, the water activity and the shrinkage was lowered, the texture (crispness) and the color of fried samples were greatly improved. The higher ultrasound and microwave power level in USMVF made a greater improvement. The total anthocyanin levels and retention of fried purple-fleshed potato chips was the highest (123.52 mg/100 g solids and 79.51% retention, respectively) among all treatments in US600M800VF process. The SEM analysis revealed a more porous and disruption microstructure in USMVF sample. Copyright © 2018 Elsevier B.V. All rights reserved.

The relationship of plasma decoy receptor 3 and coronary collateral circulation in patients with coronary artery disease.

PubMed

Yan, Youyou; Song, Dandan; Liu, Lulu; Meng, Xiuping; Qi, Chao; Wang, Junnan

2017-11-15

Previously, decoy receptor 3 (DcR3) was found to be a potential angiogenetic factor, while the relationship of DcR3 with coronary collateral circulation formation has not been investigated. In this study, we aimed to investigate whether plasma decoy receptor 3 levels was associated with CCC formation and evaluate its predictive power for CCC status in patients with coronary artery disease. Among patients who underwent coronary angiography with coronary artery disease and had a stenosis of ≥90% were included in our study. Collateral degree was graded according to Rentrope Cohen classification. Patients with grade 2 or 3 collateral degree were enrolled in good CCC group and patients with grade 0 or 1 collateral degree were enrolled in poor CCC group. Plasma DcR3 level was significantly higher in good CCC group (328.00±230.82 vs 194.84±130.63ng/l, p<0.01) and positively correlated with Rentrope grade (p<0.01). In addition, plasma DcR3 was also positively correlated with VEGF-A. Both ROC (receiver operating characteristic curve) and multinomial logistical regression analysis showed that plasma DcR3 displayed potent predictive power for CCC status. Higher plasma DcR3 level was related to better CCC formation and displayed potent predictive power for CCC status. Copyright © 2017. Published by Elsevier Inc.

Impute DC link (IDCL) cell based power converters and control thereof

DOEpatents

Divan, Deepakraj M.; Prasai, Anish; Hernendez, Jorge; Moghe, Rohit; Iyer, Amrit; Kandula, Rajendra Prasad

2016-04-26

Power flow controllers based on Imputed DC Link (IDCL) cells are provided. The IDCL cell is a self-contained power electronic building block (PEBB). The IDCL cell may be stacked in series and parallel to achieve power flow control at higher voltage and current levels. Each IDCL cell may comprise a gate drive, a voltage sharing module, and a thermal management component in order to facilitate easy integration of the cell into a variety of applications. By providing direct AC conversion, the IDCL cell based AC/AC converters reduce device count, eliminate the use of electrolytic capacitors that have life and reliability issues, and improve system efficiency compared with similarly rated back-to-back inverter system.

Identification of the Best Anthropometric Predictors of Serum High- and Low-Density Lipoproteins Using Machine Learning.

PubMed

Lee, Bum Ju; Kim, Jong Yeol

2015-09-01

Serum high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol levels are associated with risk factors for various diseases and are related to anthropometric measures. However, controversy remains regarding the best anthropometric indicators of the HDL and LDL cholesterol levels. The objectives of this study were to identify the best predictors of HDL and LDL cholesterol using statistical analyses and two machine learning algorithms and to compare the predictive power of combined anthropometric measures in Korean adults. A total of 13,014 subjects participated in this study. The anthropometric measures were assessed with binary logistic regression (LR) to evaluate statistically significant differences between the subjects with normal and high LDL cholesterol levels and between the subjects with normal and low HDL cholesterol levels. LR and the naive Bayes algorithm (NB), which provides more reasonable and reliable results, were used in the analyses of the predictive power of individual and combined measures. The best predictor of HDL was the rib to hip ratio (p =< 0.0001; odds ratio (OR) = 1.895; area under curve (AUC) = 0.681) in women and the waist to hip ratio (WHR) (p =< 0.0001; OR = 1.624; AUC = 0.633) in men. In women, the strongest indicator of LDL was age (p =< 0.0001; OR = 1.662; AUC by NB = 0.653 ; AUC by LR = 0.636). Among the anthropometric measures, the body mass index (BMI), WHR, forehead to waist ratio, forehead to rib ratio, and forehead to chest ratio were the strongest predictors of LDL; these measures had similar predictive powers. The strongest predictor in men was BMI (p =< 0.0001; OR = 1.369; AUC by NB = 0.594; AUC by LR = 0.595 ). The predictive power of almost all individual anthropometric measures was higher for HDL than for LDL, and the predictive power for both HDL and LDL in women was higher than for men. A combination of anthropometric measures slightly improved the predictive power for both HDL and LDL cholesterol. The best indicator for HDL and LDL might differ according to the type of cholesterol and the gender. In women, but not men, age was the variable that strongly predicted HDL and LDL cholesterol levels. Our findings provide new information for the development of better initial screening tools for HDL and LDL cholesterol.

Advanced space power PEM fuel cell systems

NASA Technical Reports Server (NTRS)

Vanderborgh, N. E.; Hedstrom, J.; Huff, J. R.

1989-01-01

A model showing mass and heat transfer in proton exchange membrane (PEM) single cells is presented. For space applications, stack operation requiring combined water and thermal management is needed. Advanced hardware designs able to combine these two techniques are available. Test results are shown for membrane materials which can operate with sufficiently fast diffusive water transport to sustain current densities of 300 ma per square centimeter. Higher power density levels are predicted to require active water removal.

Reassessing the Efficiency Penalty from Carbon Capture in Coal-Fired Power Plants.

PubMed

Supekar, Sarang D; Skerlos, Steven J

2015-10-20

This paper examines thermal efficiency penalties and greenhouse gas as well as other pollutant emissions associated with pulverized coal (PC) power plants equipped with postcombustion CO2 capture for carbon sequestration. We find that, depending on the source of heat used to meet the steam requirements in the capture unit, retrofitting a PC power plant that maintains its gross power output (compared to a PC power plant without a capture unit) can cause a drop in plant thermal efficiency of 11.3-22.9%-points. This estimate for efficiency penalty is significantly higher than literature values and corresponds to an increase of about 5.3-7.7 US¢/kWh in the levelized cost of electricity (COE) over the 8.4 US¢/kWh COE value for PC plants without CO2 capture. The results follow from the inclusion of mass and energy feedbacks in PC power plants with CO2 capture into previous analyses, as well as including potential quality considerations for safe and reliable transportation and sequestration of CO2. We conclude that PC power plants with CO2 capture are likely to remain less competitive than natural gas combined cycle (without CO2 capture) and on-shore wind power plants, both from a levelized and marginal COE point of view.

CO2 laser drives extreme ultraviolet nano-lithography — second life of mature laser technology

NASA Astrophysics Data System (ADS)

Nowak, K. M.; Ohta, T.; Suganuma, T.; Fujimoto, J.; Mizoguchi, H.; Sumitani, A.; Endo, A.

2013-12-01

It was shown both theoretically and experimentally that nanosecond order laser pulses at 10.6 micron wavelength were superior for driving the Sn plasma extreme ultraviolet (EUV) source for nano-lithography for the reasons of higher conversion efficiency, lower production of debris and higher average power levels obtainable in CO2 media without serious problems of beam distortions and nonlinear effects occurring in competing solid-state lasers at high intensities. The renewed interest in such pulse format, wavelength, repetition rates in excess of 50 kHz and average power levels in excess of 18 kiloWatt has sparked new opportunities for a matured multi-kiloWatt CO2 laser technology. The power demand of EUV source could be only satisfied by a Master-Oscillator-Power-Amplifier system configuration, leading to a development of a new type of hybrid pulsed CO2 laser employing a whole spectrum of CO2 technology, such as fast flow systems and diffusion-cooled planar waveguide lasers, and relatively recent quantum cascade lasers. In this paper we review briefly the history of relevant pulsed CO2 laser technology and the requirements for multi-kiloWatt CO2 laser, intended for the laser-produced plasma EUV source, and present our recent advances, such as novel solid-state seeded master oscillator and efficient multi-pass amplifiers built on planar waveguide CO2 lasers.

Particle-In-Cell (PIC) simulation of long-anode magnetron

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

Verma, Rajendra Kumar, E-mail: rajendra.verma89@gmail.com; Maurya, Shivendra; Singh, Vindhyavasini Prasad

Long Anode Magnetron (LAM) is a design scheme adopted to attain greater thermal stability and higher power levels for the conventional magnetrons. So a LAM for 5MW Power level at 2.858 GHz was ‘Virtual Prototyped’ using Admittance Matching field theory (AMT) andthen a PIC Study (Beam-wave interaction) was conducted using CST Particle Studio (CST-PS) which is explained in this paper. The convincing results thus obtained were – hot resonant frequency of 2.834 GHz. Output power of 5 MW at beam voltage of 58kV and applied magnetic field of 2200 Gauss with an overall efficiency of 45%. The simulated parameters values on comparisonmore » with the E2V LAM tube (M5028) were in good agreement which validates the feasibility of the design approach.« less

Photo-detachment of negative ions in Ar-CO2 dc discharge employing Langmuir probe

NASA Astrophysics Data System (ADS)

Rodríguez, Jannet; Yousif, Farook Bashir; Fuentes, Beatriz E.; Vázquez, Federico; Rivera, Marco; López-Patiño, J.; Figueroa, Aldo; Martínez, Horacio

2018-05-01

The electronegativity of the A r - C O 2 gas mixture was investigated, and the total relative negative oxygen ion density O2- + O- in the bulk of a dc discharge has been determined employing Langmuir probe assisted laser photo-detachment. The relative electron density and absolute temperature were obtained for the mixture at discharge powers between 200 and 3000 mW and pressures between 0.2 and 0.6 mbar, employing the collisional radiative model for several Ar gas mixtures. The absolute metastable number density for 1s3 and 1s5 levels was measured, and both showed an increasing trend as a function of pressure and power. The absolute number density of the 1s5 level was found to be higher than that of the 1s3 level. Electronegativity was found to decrease as a function of power and as a function of the increasing Ar percentage in the gas mixture.

Pulsed thermionic converter study

NASA Technical Reports Server (NTRS)

1976-01-01

A nuclear electric propulsion concept using a thermionic reactor inductively coupled to a magnetoplasmadynamic accelerator (MPD arc jet) is described, and the results of preliminary analyses are presented. In this system, the MPD thruster operates intermittently at higher voltages and power levels than the thermionic generating unit. A typical thrust pulse from the MPD arc jet is characterized by power levels of 1 to 4 MWe, a duration of 1 msec, and a duty cycle of approximately 20%. The thermionic generating unit operates continuously but with a lower power level of approximately 0.4 MWe. Energy storage between thrust pulses is provided by building up a large current in an inductor using the output of the thermionic converter array. Periodically, the charging current is interrupted, and the energy stored in the magnetic field of the inductor is utilized for a short duration thrust pulse. The results of the preliminary analysis show that a coupling effectiveness of approximately 85 to 90% is feasible for a nominal 400 KWe system with an inductive unit suitable for a flight vehicle.

A Closed Brayton Power Conversion Unit Concept for Nuclear Electric Propulsion for Deep Space Missions

NASA Astrophysics Data System (ADS)

Joyner, Claude Russell; Fowler, Bruce; Matthews, John

2003-01-01

In space, whether in a stable satellite orbit around a planetary body or traveling as a deep space exploration craft, power is just as important as the propulsion. The need for power is especially important for in-space vehicles that use Electric Propulsion. Using nuclear power with electric propulsion has the potential to provide increased payload fractions and reduced mission times to the outer planets. One of the critical engineering and design aspects of nuclear electric propulsion at required mission optimized power levels is the mechanism that is used to convert the thermal energy of the reactor to electrical power. The use of closed Brayton cycles has been studied over the past 30 or years and shown to be the optimum approach for power requirements that range from ten to hundreds of kilowatts of power. It also has been found to be scalable to higher power levels. The Closed Brayton Cycle (CBC) engine power conversion unit (PCU) is the most flexible for a wide range of power conversion needs and uses state-of-the-art, demonstrated engineering approaches. It also is in use with many commercial power plants today. The long life requirements and need for uninterrupted operation for nuclear electric propulsion demands high reliability from a CBC engine. A CBC engine design for use with a Nuclear Electric Propulsion (NEP) system has been defined based on Pratt & Whitney's data from designing long-life turbo-machines such as the Space Shuttle turbopumps and military gas turbines and the use of proven integrated control/health management systems (EHMS). An integrated CBC and EHMS design that is focused on using low-risk and proven technologies will over come many of the life-related design issues. This paper will discuss the use of a CBC engine as the power conversion unit coupled to a gas-cooled nuclear reactor and the design trends relative to its use for powering electric thrusters in the 25 kWe to 100kWe power level.

The impact of the topology on cascading failures in a power grid model

NASA Astrophysics Data System (ADS)

Koç, Yakup; Warnier, Martijn; Mieghem, Piet Van; Kooij, Robert E.; Brazier, Frances M. T.

2014-05-01

Cascading failures are one of the main reasons for large scale blackouts in power transmission grids. Secure electrical power supply requires, together with careful operation, a robust design of the electrical power grid topology. Currently, the impact of the topology on grid robustness is mainly assessed by purely topological approaches, that fail to capture the essence of electric power flow. This paper proposes a metric, the effective graph resistance, to relate the topology of a power grid to its robustness against cascading failures by deliberate attacks, while also taking the fundamental characteristics of the electric power grid into account such as power flow allocation according to Kirchhoff laws. Experimental verification on synthetic power systems shows that the proposed metric reflects the grid robustness accurately. The proposed metric is used to optimize a grid topology for a higher level of robustness. To demonstrate its applicability, the metric is applied on the IEEE 118 bus power system to improve its robustness against cascading failures.

Diamond-based heat spreaders for power electronic packaging applications

NASA Astrophysics Data System (ADS)

Guillemet, Thomas

As any semiconductor-based devices, power electronic packages are driven by the constant increase of operating speed (higher frequency), integration level (higher power), and decrease in feature size (higher packing density). Although research and innovation efforts have kept these trends continuous for now more than fifty years, the electronic packaging technology is currently facing a challenge that must be addressed in order to move toward any further improvements in terms of performances or miniaturization: thermal management. Thermal issues in high-power packages strongly affect their reliability and lifetime and have now become one of the major limiting factors of power modules development. Thus, there is a strong need for materials that can sustain higher heat flux levels while safely integrating into the electronic package architecture. In such context, diamond is an attractive candidate because of its outstanding thermal conductivity, low thermal expansion, and high electrical resistivity. Its low heat capacity relative to metals such as aluminum or copper makes it however preferable for heat spreading applications (as a heat-spreader) rather than for dissipating the heat flux itself (as a heat sink). In this study, a dual diamond-based heat-spreading solution is proposed. Polycrystalline diamond films were grown through laser-assisted combustion synthesis on electronic substrates (in the U.S) while, in parallel, diamond-reinforced copper-matrix composite films were fabricated through tape casting and hot pressing (in France). These two types of diamond-based heat-spreading films were characterized and their microstructure and chemical composition were related to their thermal performances. Particular emphasize was put on the influence of interfaces on the thermal properties of the materials, either inside a single material (grain boundaries) or between dissimilar materials (film/substrate interface, matrix/reinforcement interface). Finally, the packaging potential of the two heat-spreading solutions invoked was evaluated. This study was carried out within the framework of a French-American collaboration between the Electrical Engineering department of the University of Nebraska-Lincoln (United States, U.S.) and the Institute of Condensed Matter Chemistry of the University of Bordeaux (France). This study was financed by the Office of Naval Research in the U.S., and by the Region Aquitaine in France.

Experimental study of radiation dose rate at different strategic points of the BAEC TRIGA Research Reactor.

PubMed

Ajijul Hoq, M; Malek Soner, M A; Salam, M A; Haque, M M; Khanom, Salma; Fahad, S M

2017-12-01

The 3MW TRIGA Mark-II Research Reactor of Bangladesh Atomic Energy Commission (BAEC) has been under operation for about thirty years since its commissioning at 1986. In accordance with the demand of fundamental nuclear research works, the reactor has to operate at different power levels by utilizing a number of experimental facilities. Regarding the enquiry for safety of reactor operating personnel and radiation workers, it is necessary to know the radiation level at different strategic points of the reactor where they are often worked. In the present study, neutron, beta and gamma radiation dose rate at different strategic points of the reactor facility with reactor power level of 2.4MW was measured to estimate the rising level of radiation due to its operational activities. From the obtained results high radiation dose is observed at the measurement position of the piercing beam port which is caused by neutron leakage and accordingly, dose rate at the stated position with different reactor power levels was measured. This study also deals with the gamma dose rate measurements at a fixed position of the reactor pool top surface for different reactor power levels under both Natural Convection Cooling Mode (NCCM) and Forced Convection Cooling Mode (FCCM). Results show that, radiation dose rate is higher for NCCM in compared with FCCM and increasing with the increase of reactor power. Thus, concerning the radiological safety issues for working personnel and the general public, the radiation dose level monitoring and the experimental analysis performed within this paper is so much effective and the result of this work can be utilized for base line data and code verification of the nuclear reactor. Copyright © 2017 Elsevier Ltd. All rights reserved.

Analysis of economic determinants of fertility in Iran: a multilevel approach.

PubMed

Moeeni, Maryam; Pourreza, Abolghasem; Torabi, Fatemeh; Heydari, Hassan; Mahmoudi, Mahmood

2014-08-01

During the last three decades, the Total Fertility Rate (TFR) in Iran has fallen considerably; from 6.5 per woman in 1983 to 1.89 in 2010. This paper analyzes the extent to which economic determinants at the micro and macro levels are associated with the number of children in Iranian households. Household data from the 2010 Household Expenditure and Income Survey (HEIS) is linked to provincial data from the 2010 Iran Multiple-Indicator Demographic and Health Survey (IrMIDHS), the National Census of Population and Housing conducted in 1986, 1996, 2006 and 2011, and the 1985-2010 Iran statistical year books. Fertility is measured as the number of children in each household. A random intercept multilevel Poisson regression function is specified based on a collective model of intra-household bargaining power to investigate potential determinants of the number of children in Iranian households. Ceteris paribus (other things being equal), probability of having more children drops significantly as either real per capita educational expenditure or real total expenditure of each household increase. Both the low- and the high-income households show probabilities of having more children compared to the middle-income households. Living in provinces with either higher average amount of value added of manufacturing establishments or lower average rate of house rent is associated to higher probability of having larger number of children. Higher levels of gender gap indices, resulting in household's wife's limited power over household decision-making, positively affect the probability of having more children. Economic determinants at the micro and macro levels, distribution of intra-household bargaining power between spouses and demographic covariates determined fertility behavior of Iranian households.

Analysis of economic determinants of fertility in Iran: a multilevel approach

PubMed Central

Moeeni, Maryam; Pourreza, Abolghasem; Torabi, Fatemeh; Heydari, Hassan; Mahmoudi, Mahmood

2014-01-01

Background: During the last three decades, the Total Fertility Rate (TFR) in Iran has fallen considerably; from 6.5 per woman in 1983 to 1.89 in 2010. This paper analyzes the extent to which economic determinants at the micro and macro levels are associated with the number of children in Iranian households. Methods: Household data from the 2010 Household Expenditure and Income Survey (HEIS) is linked to provincial data from the 2010 Iran Multiple-Indicator Demographic and Health Survey (IrMIDHS), the National Census of Population and Housing conducted in 1986, 1996, 2006 and 2011, and the 1985–2010 Iran statistical year books. Fertility is measured as the number of children in each household. A random intercept multilevel Poisson regression function is specified based on a collective model of intra-household bargaining power to investigate potential determinants of the number of children in Iranian households. Results: Ceteris paribus (other things being equal), probability of having more children drops significantly as either real per capita educational expenditure or real total expenditure of each household increase. Both the low- and the high-income households show probabilities of having more children compared to the middle-income households. Living in provinces with either higher average amount of value added of manufacturing establishments or lower average rate of house rent is associated to higher probability of having larger number of children. Higher levels of gender gap indices, resulting in household’s wife’s limited power over household decision-making, positively affect the probability of having more children. Conclusion: Economic determinants at the micro and macro levels, distribution of intra-household bargaining power between spouses and demographic covariates determined fertility behavior of Iranian households. PMID:25197678

Endothelial protection: avoiding air bubble formation at the phacoemulsification tip.

PubMed

Kim, Eung Kweon; Cristol, Stephen M; Kang, Shin J; Edelhauser, Henry F; Yeon, Dong-Soo; Lee, Jae Bum

2002-03-01

To investigate the conditions under which bubbles form during phacoemulsification. Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea. In the first part of the study, the partial pressure of oxygen (pO(2)) was used as a surrogate measure for the partial pressure of air. Irrigation solutions packaged in glass and plastic containers were studied. A directly vented glass bottle was also tested. The pO(2) of the various irrigation solutions was measured as the containers were emptied. In the second part, phacoemulsification procedures were performed in rabbit eyes with different power settings and different irrigation solutions. Intracameral bubble formation during the procedure was recorded. Following the phacoemulsification procedures, the corneas were stained for F-actin and examined for endothelial injury. The initial pO(2) in irrigation solutions packaged in glass bottles was about half that at atmospheric levels; in solutions packaged in plastic, it was at atmospheric levels. As irrigation solutions were drained from the container, the pO(2) of the solution tended to rise toward atmospheric levels. The rate of pO(2) increase was markedly reduced by using a directly vented glass bottle. In the phacoemulsification procedures, bubble formation was most likely to occur with higher pO(2) and higher power settings. Observation of bubbles by the surgeon was highly correlated with endothelial damage. Keeping the pO(2) low reduced the risk of endothelial damage, especially at higher phacoemulsification powers. The packaging of irrigation solutions was the most important factor in controlling the initial pO(2) of the solution. The pO(2) can be minimized throughout a phacoemulsification procedure by using a directly vented glass bottle.

High Intensity Laser Power Beaming Architecture for Space and Terrestrial Missions

NASA Technical Reports Server (NTRS)

Nayfeh, Taysir; Fast, Brian; Raible, Daniel; Dinca, Dragos; Tollis, Nick; Jalics, Andrew

2011-01-01

High Intensity Laser Power Beaming (HILPB) has been developed as a technique to achieve Wireless Power Transmission (WPT) for both space and terrestrial applications. In this paper, the system architecture and hardware results for a terrestrial application of HILPB are presented. These results demonstrate continuous conversion of high intensity optical energy at near-IR wavelengths directly to electrical energy at output power levels as high as 6.24 W from the single cell 0.8 cm2 aperture receiver. These results are scalable, and may be realized by implementing receiver arraying and utilizing higher power source lasers. This type of system would enable long range optical refueling of electric platforms, such as MUAV s, airships, robotic exploration missions and provide power to spacecraft platforms which may utilize it to drive electric means of propulsion.

Age-Associated Changes in the Spectral and Statistical Parameters of Surface Electromyogram of Tibialis Anterior.

PubMed

Siddiqi, Ariba; Arjunan, Sridhar Poosapadi; Kumar, Dinesh Kant

2016-01-01

Age-related neuromuscular change of Tibialis Anterior (TA) is a leading cause of muscle strength decline among the elderly. This study has established the baseline for age-associated changes in sEMG of TA at different levels of voluntary contraction. We have investigated the use of Gaussianity and maximal power of the power spectral density (PSD) as suitable features to identify age-associated changes in the surface electromyogram (sEMG). Eighteen younger (20-30 years) and 18 older (60-85 years) cohorts completed two trials of isometric dorsiflexion at four different force levels between 10% and 50% of the maximal voluntary contraction. Gaussianity and maximal power of the PSD of sEMG were determined. Results show a significant increase in sEMG's maximal power of the PSD and Gaussianity with increase in force for both cohorts. It was also observed that older cohorts had higher maximal power of the PSD and lower Gaussianity. These age-related differences observed in the PSD and Gaussianity could be due to motor unit remodelling. This can be useful for noninvasive tracking of age-associated neuromuscular changes.

Fission gas release during power bumping at high burnup

NASA Astrophysics Data System (ADS)

Cunningham, M. E.; Freshley, M. D.; Lanning, D. D.

1993-03-01

Research to define the behavior of Zircaloy-clad light-water reactor fuel irradiated to high burnup levels was conducted by the High Burnup Effects Program (HBEP). One activity conducted by the HBEP was to "bump" the power level of irradiated, commercial light-water reactor fuel rods to design limit linear heat generation rates at end-of-life. These bumping irradiations simulated end-of-life design limit linear heat generation rates and provided data on the effects of short-term, high power irradiations at high burnup applicable to the design and operating constraints imposed by maximum allowable fuel rod internal gas pressure limits. Based on net fission gas release during the bumping irradiations, it was observed that higher burnup rods had greater rod-average fractional fission gas release than lower burnup rods at equal bumping powers. It was also observed that a hold period of 48 hours at the peak power was insufficient to achieve equilibrium fission gas release. Finally, differences in the prebump location of fission gas, i.e., within the UO 2 matrix or at grain boundaries, affected the fission gas release during the bumping irradiations.

Power monitoring and control for large scale projects: SKA, a case study

NASA Astrophysics Data System (ADS)

Barbosa, Domingos; Barraca, João. Paulo; Maia, Dalmiro; Carvalho, Bruno; Vieira, Jorge; Swart, Paul; Le Roux, Gerhard; Natarajan, Swaminathan; van Ardenne, Arnold; Seca, Luis

2016-07-01

Large sensor-based science infrastructures for radio astronomy like the SKA will be among the most intensive datadriven projects in the world, facing very high demanding computation, storage, management, and above all power demands. The geographically wide distribution of the SKA and its associated processing requirements in the form of tailored High Performance Computing (HPC) facilities, require a Greener approach towards the Information and Communications Technologies (ICT) adopted for the data processing to enable operational compliance to potentially strict power budgets. Addressing the reduction of electricity costs, improve system power monitoring and the generation and management of electricity at system level is paramount to avoid future inefficiencies and higher costs and enable fulfillments of Key Science Cases. Here we outline major characteristics and innovation approaches to address power efficiency and long-term power sustainability for radio astronomy projects, focusing on Green ICT for science and Smart power monitoring and control.

Effect of different methods of pulse width modulation on power losses in an induction motor

NASA Astrophysics Data System (ADS)

Gulyaev, Alexander; Fokin, Dmitrii; Shuharev, Sergey; Ten, Evgenii

2017-10-01

We consider the calculation of modulation power losses in a system “induction motor-inverter” for various pulse width modulation (PWM) methods of the supply voltage. Presented values of modulation power losses are the result of modeling a system “DC link - two-level three-phase voltage inverter - induction motor - load”. In this study the power losses in a system “induction motor - inverter” are computed, as well as losses caused by higher harmonics of PWM supply voltage, followed by definition of active power consumed by the DC link for a specified value mechanical power on the induction motor shaft. Mechanical power was determined by the rotation speed and the torque on the motor shaft in various quasi-sinusoidal supply voltage PWM modes. These calculations reveal the best coefficient of performance (COP) in a system of a variable frequency drive (VFD) with independent voltage inverter controlled by induction motor PWM.

Assessment of soil contamination by (210)Po and (210)Pb around heavy oil and natural gas fired power plants.

PubMed

Al-Masri, M S; Haddad, Kh; Doubal, A W; Awad, I; Al-Khatib, Y

2014-06-01

Soil contamination by (210)Pb and (210)Po around heavy oil and natural gas power plants has been investigated; fly and bottom ash containing enhanced levels of (210)Pb and (210)Po were found to be the main source of surface soil contamination. The results showed that (210)Pb and (210)Po in fly-ash (economizer, superheater) is highly enriched with (210)Pb and (210)Po, while bottom-ash (boiler) is depleted. The highest (210)Pb and (210)Po activity concentrations were found to be in economizer ash, whereas the lowest activity concentration was in the recirculator ash. On the other hand, (210)Pb and (210)Po activity concentrations in soil samples were found to be higher inside the plant site area than those samples collected from surrounding areas. The highest levels were found in the vicinity of Mhardeh and Tishreen power plants; both plants are operated by heavy oil and natural fuels, while the lowest values were found to be in those samples collected from Nasrieh power plant, which is only operated by one type of fuel, viz. natural gas. In addition, the levels of surface soil contamination have decreased as the distance from the power plant site center increased. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effects of cold plasma treatment on alfalfa seed growth under simulated drought stress

NASA Astrophysics Data System (ADS)

Jinkui, FENG; Decheng, WANG; Changyong, SHAO; Lili, ZHANG; Xin, TANG

2018-03-01

The effect of different cold plasma treatments on the germination and seedling growth of alfalfa (Medicago sativa L.) seeds under simulated drought stress conditions was investigated. Polyethyleneglycol-6000 (PEG 6000)with the mass fraction of 0% (purified water), 5%, 10%, and 15% were applied to simulate the drought environment. The alfalfa seeds were treated with 15 different power levels ranged between 0-280 W for 15 s. The germination potential, germination rate, germination index, seedling root length, seedling height, and vigor index were investigated. Results indicated significant differences between treated with proper power and untreated alfalfa seeds. With the increase of treatment power, these indexes mentioned above almost presented bimodal curves. Under the different mass fractions of PEG 6000, results showed that the lower power led to increased germination, and the seedlings presented good adaptability to different drought conditions. Meanwhile, higher power levels resulted in a decreased germination rate. Seeds treated with 40 W resulted in higher germination potential, germination rate, seedling height, root length, and vigor index. Vigor indexes of the treated seeds under different PEG 6000 stresses increased by 38.68%, 43.91%, 74.34%, and 39.20% respectively compared to CK0-0, CK5-0, CK10-0, and CK15-0 (the control sample under 0%, 5%, 10%, and 15% PEG 6000). Therefore, 40 W was regarded as the best treatment in this research. Although the trend indexes of alfalfa seeds treated with the same power were statistically the same under different PEG 6000 stresses, the cold plasma treatment had a significant effect on the adaptability of alfalfa seeds in different drought environments. Thus, this kind of treatment is worth implementing to promote seed growth under drought situations.

Off-resonance frequency operation for power transfer in a loosely coupled air core transformer

DOEpatents

Scudiere, Matthew B

2012-11-13

A power transmission system includes a loosely coupled air core transformer having a resonance frequency determined by a product of inductance and capacitance of a primary circuit including a primary coil. A secondary circuit is configured to have a substantially same product of inductance and capacitance. A back EMF generating device (e.g., a battery), which generates a back EMF with power transfer, is attached to the secondary circuit. Once the load power of the back EMF generating device exceeds a certain threshold level, which depends on the system parameters, the power transfer can be achieved at higher transfer efficiency if performed at an operating frequency less than the resonance frequency, which can be from 50% to 95% of the resonance frequency.

Power inversion design for ocean wave energy harvesting

NASA Astrophysics Data System (ADS)

Talebani, Anwar N.

The needs for energy sources are increasing day by day because of several factors, such as oil depletion, and global climate change due to the higher level of CO2, so the exploration of various renewable energy sources is very promising area of study. The available ocean waves can be utilized as free source of energy as the water covers 70% of the earth surface. This thesis presents the ocean wave energy as a source of renewable energy. By addressing the problem of designing efficient power electronics system to deliver 5 KW from the induction generator to the grid with less possible losses and harmonics as possible and to control current fed to the grid to successfully harvest ocean wave energy. We design an AC-DC full bridge rectifier converter, and a DC-DC boost converter to harvest wave energy from AC to regulated DC. In order to increase the design efficiency, we need to increase the power factor from (0.5-0.6) to 1. This is accomplished by designing the boost converter with power factor correction in continues mode with RC circuit as an input to the boost converter power factor correction. This design results in a phase shift between the input current and voltage of the full bridge rectifier to generate a small reactive power. The reactive power is injected to the induction generator to maintain its functionality by generating a magnetic field in its stator. Next, we design a single-phase pulse width modulator full bridge voltage source DC-AC grid-tied mode inverter to harvest regulated DC wave energy to AC. The designed inverter is modulated by inner current loop, to control current injected to the grid with minimal filter component to maintain power quality at the grid. The simulation results show that our design successfully control the current level fed to the grid. It is noteworthy that the simulated efficiency is higher than the calculated one since we used an ideal switch in the simulated circuit.

Three-Level De-Multiplexed Dual-Branch Complex Delta-Sigma Transmitter.

PubMed

Arfi, Anis Ben; Elsayed, Fahmi; Aflaki, Pouya M; Morris, Brad; Ghannouchi, Fadhel M

2018-02-20

In this paper, a dual-branch topology driven by a Delta-Sigma Modulator (DSM) with a complex quantizer, also known as the Complex Delta Sigma Modulator (CxDSM), with a 3-level quantized output signal is proposed. By de-multiplexing the 3-level Delta-Sigma-quantized signal into two bi-level streams, an efficiency enhancement over the operational frequency range is achieved. The de-multiplexed signals drive a dual-branch amplification block composed of two switch-mode back-to-back power amplifiers working at peak power. A signal processing technique known as quantization noise reduction with In-band Filtering (QNRIF) is applied to each of the de-multiplexed streams to boost the overall performances; particularly the Adjacent Channel Leakage Ratio (ACLR). After amplification, the two branches are combined using a non-isolated combiner, preserving the efficiency of the transmitter. A comprehensive study on the operation of this topology and signal characteristics used to drive the dual-branch Switch-Mode Power Amplifiers (SMPAs) was established. Moreover, this work proposes a highly efficient design of the amplification block based on a back-to-back power topology performing a dynamic load modulation exploiting the non-overlapping properties of the de-multiplexed Complex DSM signal. For experimental validation, the proposed de-multiplexed 3-level Delta-Sigma topology was implemented on the BEEcube™ platform followed by the back-to-back Class-E switch-mode power amplification block. The full transceiver is assessed using a 4th-Generation mobile communications standard LTE (Long Term Evolution) standard 1.4 MHz signal with a peak to average power ratio (PAPR) of 8 dB. The dual-branch topology exhibited a good linearity and a coding efficiency of the transmitter chain higher than 72% across the band of frequency from 1.8 GHz to 2.7 GHz.

Rolling resistance and propulsion efficiency of manual and power-assisted wheelchairs.

PubMed

Pavlidou, Efthymia; Kloosterman, Marieke G M; Buurke, Jaap H; Rietman, Johan S; Janssen, Thomas W J

2015-11-01

Rolling resistance is one of the main forces resisting wheelchair propulsion and thus affecting stress exerted on the upper limbs. The present study investigates the differences in rolling resistance, propulsion efficiency and energy expenditure required by the user during power-assisted and manual propulsion. Different tire pressures (50%, 75%, 100%) and two different levels of motor assistance were tested. Drag force, energy expenditure and propulsion efficiency were measured in 10 able-bodied individuals under different experimental settings on a treadmill. Results showed that drag force levels were significantly higher in the 50%, compared to the 75% and 100% inflation conditions. In terms of wheelchair type, the manual wheelchair displayed significantly lower drag force values than the power-assisted one. The use of extra-power-assisted wheelchair appeared to be significantly superior to conventional power-assisted and manual wheelchairs concerning both propulsion efficiency and energy expenditure required by the user. Overall, the results of the study suggest that the use of power-assisted wheelchair was more efficient and required less energy input by the user, depending on the motor assistance provided. Copyright © 2015 IPEM. Published by Elsevier Ltd. All rights reserved.

Quantity, Quality, and Availability of Waste Heat from United States Thermal Power Generation.

PubMed

Gingerich, Daniel B; Mauter, Meagan S

2015-07-21

Secondary application of unconverted heat produced during electric power generation has the potential to improve the life-cycle fuel efficiency of the electric power industry and the sectors it serves. This work quantifies the residual heat (also known as waste heat) generated by U.S. thermal power plants and assesses the intermittency and transport issues that must be considered when planning to utilize this heat. Combining Energy Information Administration plant-level data with literature-reported process efficiency data, we develop estimates of the unconverted heat flux from individual U.S. thermal power plants in 2012. Together these power plants discharged an estimated 18.9 billion GJ(th) of residual heat in 2012, 4% of which was discharged at temperatures greater than 90 °C. We also characterize the temperature, spatial distribution, and temporal availability of this residual heat at the plant level and model the implications for the technical and economic feasibility of its end use. Increased implementation of flue gas desulfurization technologies at coal-fired facilities and the higher quality heat generated in the exhaust of natural gas fuel cycles are expected to increase the availability of residual heat generated by 10.6% in 2040.

Making Stories, Making Sense.

ERIC Educational Resources Information Center

Rubin, Andee

1980-01-01

Describes a set of tools (called Story Maker, Pre-Fab Story Maker, and Story Maker Maker) for teaching creative writing that takes advantage of the potential power of the social situation in the classroom, focuses on higher-level structures in text, and integrates reading and writing in school. (AEA)

Engineering the Implementation of Pumped Hydro Energy Storage in the Arizona Power Grid

NASA Astrophysics Data System (ADS)

Dixon, William Jesse J.

This thesis addresses the issue of making an economic case for bulk energy storage in the Arizona bulk power system. Pumped hydro energy storage (PHES) is used in this study. Bulk energy storage has often been suggested for large scale electric power systems in order to levelize load (store energy when it is inexpensive [energy demand is low] and discharge energy when it is expensive [energy demand is high]). It also has the potential to provide opportunities to avoid transmission and generation expansion, and provide for generation reserve margins. As the level of renewable energy resources increases, the uncertainty and variability of wind and solar resources may be improved by bulk energy storage technologies. For this study, the MATLab software platform is used, a mathematical based modeling language, optimization solvers (specifically Gurobi), and a power flow solver (PowerWorld) are used to simulate an economic dispatch problem that includes energy storage and transmission losses. A program is created which utilizes quadratic programming to analyze various cases using a 2010 summer peak load from the Arizona portion of the Western Electricity Coordinating Council (WECC) system. Actual data from industry are used in this test bed. In this thesis, the full capabilities of Gurobi are not utilized (e.g., integer variables, binary variables). However, the formulation shown here does create a platform such that future, more sophisticated modeling may readily be incorporated. The developed software is used to assess the Arizona test bed with a low level of energy storage to study how the storage power limit effects several optimization outputs such as the system wide operating costs. Large levels of energy storage are then added to see how high level energy storage affects peak shaving, load factor, and other system applications. Finally, various constraint relaxations are made to analyze why the applications tested eventually approach a constant value. This research illustrates the use of energy storage which helps minimize the system wide generator operating cost by "shaving" energy off of the peak demand. The thesis builds on the work of another recent researcher with the objectives of strengthening the assumptions used, checking the solutions obtained, utilizing higher level simulation languages to affirm results, and expanding the results and conclusions. One important point not fully discussed in the present thesis is the impact of efficiency in the pumped hydro cycle. The efficiency of the cycle for modern units is estimated at higher than 90%. Inclusion of pumped hydro losses is relegated to future work.

Wood and bark of Pinus halepensis as archives of heavy metal pollution in the Mediterranean Region.

PubMed

Rodríguez Martin, José Antonio; Gutiérrez, Carmen; Torrijos, Manuel; Nanos, Nikos

2018-04-18

Natural levels of heavy metals (HM) have increased during the industrial era to the point of posing a serious threat to the environment. The use of tree species to record contamination is a well-known practice. The objective of the study was to compare HM levels under different pollution conditions: a) soil pollution due to mining waste; b) atmospheric pollution due to coal-fired power plant emissions. We report significant HM enrichment in Pinus halepensis tissues. Near a burning power plant, Pb content in a tree wood was 2.5-fold higher that in natural areas (no pollution; NP). In mining areas, Cd content was 25-fold higher than NP. The hypothesis that HM contents in tree rings should register pollution is debatable. HM uptake by pines from soil, detoxification mechanisms and resuspended local soil dust is involved in HM contents in wood and bark. Copyright © 2018 Elsevier Ltd. All rights reserved.

Terahertz light-emitting graphene-channel transistor toward single-mode lasing

NASA Astrophysics Data System (ADS)

Yadav, Deepika; Tamamushi, Gen; Watanabe, Takayuki; Mitsushio, Junki; Tobah, Youssef; Sugawara, Kenta; Dubinov, Alexander A.; Satou, Akira; Ryzhii, Maxim; Ryzhii, Victor; Otsuji, Taiichi

2018-03-01

A distributed feedback dual-gate graphene-channel field-effect transistor (DFB-DG-GFET) was fabricated as a current-injection terahertz (THz) light-emitting laser transistor. We observed a broadband emission in a 1-7.6-THz range with a maximum radiation power of 10 μW as well as a single-mode emission at 5.2 THz with a radiation power of 0.1 μW both at 100 K when the carrier injection stays between the lower cutoff and upper cutoff threshold levels. The device also exhibited peculiar nonlinear threshold-like behavior with respect to the current-injection level. The LED-like broadband emission is interpreted as an amplified spontaneous THz emission being transcended to a single-mode lasing. Design constraints on waveguide structures for better THz photon field confinement with higher gain overlapping as well as DFB cavity structures with higher Q factors are also addressed towards intense, single-mode continuous wave THz lasing at room temperature.

Wind power development in the United States: Effects of policies and electricity transmission congestion

NASA Astrophysics Data System (ADS)

Hitaj, Claudia

In this dissertation, I analyze the drivers of wind power development in the United States as well as the relationship between renewable power plant location and transmission congestion and emissions levels. I first examine the role of government renewable energy incentives and access to the electricity grid on investment in wind power plants across counties from 1998-2007. The results indicate that the federal production tax credit, state-level sales tax credit and production incentives play an important role in promoting wind power. In addition, higher wind power penetration levels can be achieved by bringing more parts of the electricity transmission grid under independent system operator regulation. I conclude that state and federal government policies play a significant role in wind power development both by providing financial support and by improving physical and procedural access to the electricity grid. Second, I examine the effect of renewable power plant location on electricity transmission congestion levels and system-wide emissions levels in a theoretical model and a simulation study. A new renewable plant takes the effect of congestion on its own output into account, but ignores the effect of its marginal contribution to congestion on output from existing plants, which results in curtailment of renewable power. Though pricing congestion removes the externality and reduces curtailment, I find that in the absence of a price on emissions, pricing congestion may in some cases actually increase system-wide emissions. The final part of my dissertation deals with an econometric issue that emerged from the empirical analysis of the drivers of wind power. I study the effect of the degree of censoring on random-effects Tobit estimates in finite sample with a particular focus on severe censoring, when the percentage of uncensored observations reaches 1 to 5 percent. The results show that the Tobit model performs well even at 5 percent uncensored observations with the bias in the Tobit estimates remaining at or below 5 percent. Under severe censoring (1 percent uncensored observations), large biases appear in the estimated standard errors and marginal effects. These are generally reduced as the sample size increases in both N and T.

Nitrogen Dioxide in Indoor Ice Skating Facilities: An International Survey.

PubMed

Brauer, Michael; Lee, Kiyoung; Spengler, John D; Salonen, Raimo O; Pennanen, Arto; Braathen, Ole Anders; Miskovic, Eva Mihalikova And Peter; Nozaki, Atsuo; Tsuzuki, Toshifumi; Rui-Jin, Song; Qing-Xiang, Yang Xu And Zeng; Drahonovska, Hana; Kjaergaard, Søren

1997-10-01

An international survey of nitrogen dioxide (NO 2 ) levels inside indoor ice skating facilities was conducted. One-week average NO 2 concentrations were measured inside and outside of 332 ice rinks located in nine countries. Each rink manager also completed a questionnaire describing the building, the resurfacing machines, and their use patterns. The (arithmetic) mean NO 2 level for all rinks in the study was 228 ppb, with a range of 1-2,680 ppb, based on a sample collected at breathing height and adjacent to the ice surface. The mean of the second indoor sample (collected at a spectator's area) was 221 ppb, with a range of 1-3,175 ppb. The ratio of the indoor to outdoor NO 2 concentrations was above 1 for 95% of the rinks sampled, indicating the presence of an indoor NO 2 source (mean indoor:outdoor ratio = 20). Estimates of short-term NO 2 concentrations indicated that as many as 40% of the sampled rinks would have exceeded the World Health Organization 1-hour guideline value of 213 ppb NO 2 for indoor air. Statistically significant associations were observed between NO 2 levels and the type of fuel used to power the resurfacer, the absence of a catalytic converter on a resurfacer, and the use of an ice edger. There were also indications that decreased use of mechanical ventilation, increased number of resurfacing operations per day, and smaller rink volumes were associated with increased NO 2 levels. In rinks where the main resurfacer was powered by propane, the NO 2 concentrations were higher than in those with gasoline-powered resurfacers, while the latter had NO 2 concentrations higher than in those using diesel. Rinks where the main resurfacer was electric had the lowest indoor NO 2 concentrations, similar to the levels measured outdoor.

The effect of resistance level and stability demands on recruitment patterns and internal loading of spine in dynamic flexion and extension using a simple trunk model.

PubMed

Zeinali-Davarani, Shahrokh; Shirazi-Adl, Aboulfazl; Dariush, Behzad; Hemami, Hooshang; Parnianpour, Mohamad

2011-07-01

The effects of external resistance on the recruitment of trunk muscles in sagittal movements and the coactivation mechanism to maintain spinal stability were investigated using a simple computational model of iso-resistive spine sagittal movements. Neural excitation of muscles was attained based on inverse dynamics approach along with a stability-based optimisation. The trunk flexion and extension movements between 60° flexion and the upright posture against various resistance levels were simulated. Incorporation of the stability constraint in the optimisation algorithm required higher antagonistic activities for all resistance levels mostly close to the upright position. Extension movements showed higher coactivation with higher resistance, whereas flexion movements demonstrated lower coactivation indicating a greater stability demand in backward extension movements against higher resistance at the neighbourhood of the upright posture. Optimal extension profiles based on minimum jerk, work and power had distinct kinematics profiles which led to recruitment patterns with different timing and amplitude of activation.

Volume and Mass Estimation of Three-Phase High Power Transformers for Space Applications

NASA Technical Reports Server (NTRS)

Kimnach, Greg L.

2004-01-01

Spacecraft historically have had sub-1kW(sub e), electrical requirements for GN&C, science, and communications: Galileo at 600W(sub e), and Cassini at 900W(sub e), for example. Because most missions have had the same order of magnitude power requirements, the Power Distribution Systems (PDS) use existing, space-qualified technology and are DC. As science payload and mission duration requirements increase, however, the required electrical power increases. Subsequently, this requires a change from a passive energy conversion (solar arrays and batteries) to dynamic (alternator, solar dynamic, etc.), because dynamic conversion has higher thermal and conversion efficiencies, has higher power densities, and scales more readily to higher power levels. Furthermore, increased power requirements and physical distribution lengths are best served with high-voltage, multi-phase AC to maintain distribution efficiency and minimize voltage drops. The generated AC-voltage must be stepped-up (or down) to interface with various subsystems or electrical hardware. Part of the trade-space design for AC distribution systems is volume and mass estimation of high-power transformers. The volume and mass are functions of the power rating, operating frequency, the ambient and allowable temperature rise, the types and amount of heat transfer available, the core material and shape, the required flux density in a core, the maximum current density, etc. McLyman has tabulated the performance of a number of transformers cores and derived a "cookbook" methodology to determine the volume of transformers, whereas Schawrze had derived an empirical method to estimate the mass of single-phase transformers. Based on the work of McLyman and Schwarze, it is the intent herein to derive an empirical solution to the volume and mass estimation of three-phase, laminated EI-core power transformers, having radiated and conducted heat transfer mechanisms available. Estimation of the mounting hardware, connectors, etc. is not included.

The relationship between wind power, electricity demand and winter weather patterns in Great Britain

NASA Astrophysics Data System (ADS)

Thornton, Hazel E.; Scaife, Adam A.; Hoskins, Brian J.; Brayshaw, David J.

2017-06-01

Wind power generation in Great Britain has increased markedly in recent years. However due to its intermittency its ability to provide power during periods of high electricity demand has been questioned. Here we characterise the winter relationship between electricity demand and the availability of wind power. Although a wide range of wind power capacity factors is seen for a given demand, the average capacity factor reduces by a third between low and high demand. However, during the highest demand average wind power increases again, due to strengthening easterly winds. The nature of the weather patterns affecting Great Britain are responsible for this relationship. High demand is driven by a range of high pressure weather types, each giving cold conditions, but variable wind power availability. Offshore wind power is sustained at higher levels and offers a more secure supply compared to that onshore. However, during high demand periods in Great Britain neighbouring countries may struggle to provide additional capacity due to concurrent low temperatures and low wind power availability.

Variability in Laboratory vs. Field Testing of Peak Power, Torque, and Time of Peak Power Production Among Elite Bicycle Motocross Cyclists.

PubMed

Rylands, Lee P; Roberts, Simon J; Hurst, Howard T

2015-09-01

The aim of this study was to ascertain the variation in elite male bicycle motocross (BMX) cyclists' peak power, torque, and time of power production during laboratory and field-based testing. Eight elite male BMX riders volunteered for the study, and each rider completed 3 maximal sprints using both a Schoberer Rad Messtechnik (SRM) ergometer in the laboratory and a portable SRM power meter on an Olympic standard indoor BMX track. The results revealed a significantly higher peak power (p ≤ 0.001, 34 ± 9%) and reduced time of power production (p ≤ 0.001, 105 ± 24%) in the field tests when compared with laboratory-derived values. Torque was also reported to be lower in the laboratory tests but not to an accepted level of significance (p = 0.182, 6 ± 8%). These results suggest that field-based testing may be a more effective and accurate measure of a BMX rider's peak power, torque, and time of power production.

Modeling and Simulation of Linear and Nonlinear MEMS Scale Electromagnetic Energy Harvesters for Random Vibration Environments

PubMed Central

Sassani, Farrokh

2014-01-01

The simulation results for electromagnetic energy harvesters (EMEHs) under broad band stationary Gaussian random excitations indicate the importance of both a high transformation factor and a high mechanical quality factor to achieve favourable mean power, mean square load voltage, and output spectral density. The optimum load is different for random vibrations and for sinusoidal vibration. Reducing the total damping ratio under band-limited random excitation yields a higher mean square load voltage. Reduced bandwidth resulting from decreased mechanical damping can be compensated by increasing the electrical damping (transformation factor) leading to a higher mean square load voltage and power. Nonlinear EMEHs with a Duffing spring and with linear plus cubic damping are modeled using the method of statistical linearization. These nonlinear EMEHs exhibit approximately linear behaviour under low levels of broadband stationary Gaussian random vibration; however, at higher levels of such excitation the central (resonant) frequency of the spectral density of the output voltage shifts due to the increased nonlinear stiffness and the bandwidth broadens slightly. Nonlinear EMEHs exhibit lower maximum output voltage and central frequency of the spectral density with nonlinear damping compared to linear damping. Stronger nonlinear damping yields broader bandwidths at stable resonant frequency. PMID:24605063

Mostly Heterosexual and Lesbian/Gay Young Adults: Differences in Mental Health and Substance Use and the Role of Minority Stress.

PubMed

Kuyper, Lisette; Bos, Henny

2016-09-01

Individuals mostly attracted to other-sex but also to same-sex partners are a distinct and common sexual orientation group with possibly increased levels of health problems. The current study examined whether mostly heterosexual individuals differed in mental health and substance use from lesbian/gay individuals and whether sexual minority risk and protective factors offer an explanation in a sample of 528 Dutch young adults (16 to 25 years old, M = 21.2 years). Mostly heterosexual participants reported higher levels of psychological distress, suicidality, drug use, and smoking than lesbian/gay participants and equal levels of binge drinking. They also reported higher levels of internalized negativity to same-sex attractions, less openness to family members and others, less community involvement, and lower numbers of lesbian/gay/bisexual friends. However, bootstrapped mediation analysis showed that the differences in minority stress risk and protective factors did not mediate most of the differences in mental health and substance use with one exception: higher levels of psychological distress were mediated by the higher levels of internalized negativity to same-sex attractions. The limited explanatory power of the minority stress factors combined with the elevated level of problems of mostly heterosexual individuals call for future studies examining other risk and protective factors.

High Capacity Battery Cell Flight Qualified

NASA Technical Reports Server (NTRS)

McKissock, Barbara I.

1997-01-01

The High Capacity Battery Cell project is an effort equally funded by the NASA Lewis Research Center and Hughes Space and Communications Company (a unit of Hughes Aircraft Company) to develop and flight qualify a higher capacity nickel hydrogen battery for continuing use on commercial spacecraft. The larger diameter, individual pressure vessel cell will provide approximately twice the power, while occupying the same volume, as the current state-of-the-art nickel hydrogen cell. These cells are also anticipated to reduce battery cost by 20 percent. The battery is currently booked for use on 26 spacecraft, with the first flight scheduled in 1997. A strong requirement for batteries with higher power levels (6 to 12 kW), long life, and reduced cost was identified in studies of the needs of commercial communications spacecraft. With the design developed in this effort, the higher power level was accommodated without having to modify the rest of the existing spacecraft bus. This design scaled-up the existing state-of-the-art nickel hydrogen battery cell from a 3.5-in., 50-Ahr cell to a 5.5-in., 350-Ahr cell. An improvement in cycle life was also achieved by the use of the 26-percent KOH electrolyte design developed by NASA Lewis. The cell design was completed, and flight batteries were built and flight qualified by Hughes Space and Communications Company with input from NASA Lewis. Two batteries were shipped in September 1996 to undergo life cycle testing under the purview of NASA Lewis.

Maximum thrust mode evaluation

NASA Technical Reports Server (NTRS)

Orme, John S.; Nobbs, Steven G.

1995-01-01

Measured reductions in acceleration times which resulted from the application of the F-15 performance seeking control (PSC) maximum thrust mode during the dual-engine test phase is presented as a function of power setting and flight condition. Data were collected at altitudes of 30,000 and 45,000 feet at military and maximum afterburning power settings. The time savings for the supersonic acceleration is less than at subsonic Mach numbers because of the increased modeling and control complexity. In addition, the propulsion system was designed to be optimized at the mid supersonic Mach number range. Recall that even though the engine is at maximum afterburner, PSC does not trim the afterburner for the maximum thrust mode. Subsonically at military power, time to accelerate from Mach 0.6 to 0.95 was cut by between 6 and 8 percent with a single engine application of PSC, and over 14 percent when both engines were optimized. At maximum afterburner, the level of thrust increases were similar in magnitude to the military power results, but because of higher thrust levels at maximum afterburner and higher aircraft drag at supersonic Mach numbers the percentage thrust increase and time to accelerate was less than for the supersonic accelerations. Savings in time to accelerate supersonically at maximum afterburner ranged from 4 to 7 percent. In general, the maximum thrust mode has performed well, demonstrating significant thrust increases at military and maximum afterburner power. Increases of up to 15 percent at typical combat-type flight conditions were identified. Thrust increases of this magnitude could be useful in a combat situation.

Influences of social power and normative support on condom use decisions: a research synthesis

PubMed Central

Albarracín, D.; Kumkale, G. T.; Johnson, B. T.

2016-01-01

A meta-analysis of 58 studies involving 30,270 participants examined how study population and methodological characteristics influence the associations among norms, control perceptions, attitudes, intentions and behaviour in the area of condom use. Findings indicated that control perceptions generally correlated more strongly among members of societal groups that lack power, including female, younger individuals, ethnic-minorities and people with lower educational levels. Furthermore, norms generally had stronger influences among younger individuals and among people who have greater access to informational social support, including males, ethnic majorities and people with higher levels of education. These findings are discussed in the context of HIV prevention efforts. PMID:15370059

Design and Implementation of a Unified Command and Control Architecture for Multiple Cooperative Unmanned Vehicles Utilizing Commercial Off the Shelf Components

DTIC Science & Technology

2015-12-24

network, allowing each to communicate with all nodes on the network. Additionally , the transmission power will be turned down to the lowest value . This...reserved for these unmanned agents are gen- erally too dull, dirty, dangerous, or difficult for onboard human pilots to complete. Additionally , the use...architectures do have a much higher level of complexity than single vehicle architectures. Additionally , the weight, size, and power limitations of the

A helicopter handling-qualities study of the effects of engine response characteristics, height-control dynamics, and excess power on nap-of-the-Earth operations

NASA Technical Reports Server (NTRS)

Corliss, L. D.

1982-01-01

The helicopter configuration with an rpm-governed gas-turbine engine was examined. A wide range of engine response time, vehicle damping and sensitivity, and excess power levels was studied. The data are compared with the existing handling-qualities specifications, MIL-F-83300 and AGARD 577, and in general show a need for higher minimums when performing such NOE maneuvers as a dolphin and bob-up task.

Effects of anode material on arcjet performance

NASA Technical Reports Server (NTRS)

Sankovic, John M.; Curran, Frank M.; Larson, C. A.

1992-01-01

Anodes fabricated from four different materials were tested in a modular arcjet thruster at 1 kW power level on nitrogen/hydrogen mixtures. A two-percent thoriated tungsten anode served as the control. Graphite was chosen for its ease in fabrication, but experienced severe erosion in the constrictor and diverging side. Hafnium carbide and lanthanum hexaboride were chosen for their low work functions but failed due to thermal stress and reacted with the propellant. When compared to the thoriated tungsten nozzle, thruster performance was significantly lower for the lanthanum hexaboride insert and the graphite nozzle, but was slightly higher for the hafnium carbide nozzle. Both the lanthanum hexaboride and hafnium carbide nozzle operated at higher voltages. An attempt was made to duplicate higher performance hafnium carbide results, but repeated attempts at machining a second anode insert were unsuccessful. Graphite, hafnium carbide, and lanthanum hexaboride do not appear viable anode materials for low power arcjet thrusters.

Upper Limb Muscle and Brain Activity in Light Assembly Task on Different Load Levels

NASA Astrophysics Data System (ADS)

Zadry, Hilma Raimona; Dawal, Siti Zawiah Md.; Taha, Zahari

2010-10-01

A study was conducted to investigate the effect of load on upper limb muscles and brain activities in light assembly task. The task was conducted at two levels of load (Low and high). Surface electromyography (EMG) was used to measure upper limb muscle activities of twenty subjects. Electroencephalography (EEG) was simultaneously recorded with EMG to record brain activities from Fz, Pz, O1 and O2 channels. The EMG Mean Power Frequency (MPF) of the right brachioradialis and the left upper trapezius activities were higher on the high-load task compared to low-load task. The EMG MPF values also decrease as time increases, that reflects muscle fatigue. Mean power of the EEG alpha bands for the Fz-Pz channels were found to be higher on the high-load task compared to low-load task, while for the O1-O2 channels, they were higher on the low-load task than on the high-load task. These results indicated that the load levels effect the upper limb muscle and brain activities. The high-load task will increase muscle activities on the right brachioradialis and the left upper tapezius muscles, and will increase the awareness and motivation of the subjects. Whilst the low-load task can generate drowsiness earlier. It signified that the longer the time and the more heavy of the task, the subjects will be more fatigue physically and mentally.

Radiation damage and annealing of lithium-doped silicon solar cells

NASA Technical Reports Server (NTRS)

Statler, R. L.

1971-01-01

Evidence has been presented that a lithium-diffused crucible-grown silicon solar cell can be made with better efficiency than the flight-quality n p 10 ohms-cm solar cell. When this lithium cell is exposed to a continuous radiation evironment at 60 C (electron spectrum from gamma rays) it has a higher power output than the N/P cell after a fluence equivalent to 1 MeV. A comparison of annealing of proton- and electron-damage in this lithium cell reveals a decidedly faster rate of recovery and higher level of recoverable power from the proton effects. Therefore, the lithium cell shows a good potential for many space missions where the proton flux is a significant fraction of the radiation field to be encountered.

Bias-field controlled phasing and power combination of gyromagnetic nonlinear transmission lines

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

Reale, D. V., E-mail: david.reale@ttu.edu; Bragg, J.-W. B.; Gonsalves, N. R.

2014-05-15

Gyromagnetic Nonlinear Transmission Lines (NLTLs) generate microwaves through the damped gyromagnetic precession of the magnetic moments in ferrimagnetic material, and are thus utilized as compact, solid-state, frequency agile, high power microwave (HPM) sources. The output frequency of a NLTL can be adjusted by control of the externally applied bias field and incident voltage pulse without physical alteration to the structure of the device. This property provides a frequency tuning capability not seen in many conventional e-beam based HPM sources. The NLTLs developed and tested are mesoband sources capable of generating MW power levels in the L, S, and C bandsmore » of the microwave spectrum. For an individual NLTL the output power at a given frequency is determined by several factors including the intrinsic properties of the ferrimagnetic material and the transmission line structure. Hence, if higher power levels are to be achieved, it is necessary to combine the outputs of multiple NLTLs. This can be accomplished in free space using antennas or in a transmission line via a power combiner. Using a bias-field controlled delay, a transient, high voltage, coaxial, three port, power combiner was designed and tested. Experimental results are compared with the results of a transient COMSOL simulation to evaluate combiner performance.« less

Bias-field controlled phasing and power combination of gyromagnetic nonlinear transmission lines.

PubMed

Reale, D V; Bragg, J-W B; Gonsalves, N R; Johnson, J M; Neuber, A A; Dickens, J C; Mankowski, J J

2014-05-01

Gyromagnetic Nonlinear Transmission Lines (NLTLs) generate microwaves through the damped gyromagnetic precession of the magnetic moments in ferrimagnetic material, and are thus utilized as compact, solid-state, frequency agile, high power microwave (HPM) sources. The output frequency of a NLTL can be adjusted by control of the externally applied bias field and incident voltage pulse without physical alteration to the structure of the device. This property provides a frequency tuning capability not seen in many conventional e-beam based HPM sources. The NLTLs developed and tested are mesoband sources capable of generating MW power levels in the L, S, and C bands of the microwave spectrum. For an individual NLTL the output power at a given frequency is determined by several factors including the intrinsic properties of the ferrimagnetic material and the transmission line structure. Hence, if higher power levels are to be achieved, it is necessary to combine the outputs of multiple NLTLs. This can be accomplished in free space using antennas or in a transmission line via a power combiner. Using a bias-field controlled delay, a transient, high voltage, coaxial, three port, power combiner was designed and tested. Experimental results are compared with the results of a transient COMSOL simulation to evaluate combiner performance.

The Quality Characteristics of Salted Ground Pork Patties Containing Various Fat Levels by Microwave Cooking

PubMed Central

Jeong, Jong Youn; Lim, Seung Taek; Kim, Cheon Jei

2016-01-01

This study was carried out to evaluate the effects of fat level on the microwave cooking properties of ground pork patties with NaCl (1.5%). Ground pork patties were processed from pork hams to achieve fat levels of 10%, 15%, 20%, and 25%, respectively. Each patty was cooked from a thawed state to 75℃ in a microwave oven at full power (700 W). After microwave cooking, protein content, moisture content, fat retention, and shear force values in patties decreased as fat level increased from 10 to 25%. As fat level increased, cooking time decreased but total cooking loss and drip loss were increased, whereas slight differences in diameter reduction and thickness of patties were observed. In raw patties, 10% fat patties had lower L* values and higher a* values compared to patties with more fat, but these differences were reduced when patties were cooked. Patties with 10% fat showed a more pink color on the surface and interior than patties with a higher fat content but more air pockets were noted in higher-fat patties. Higher-fat patties were more tender, juicy, and oily than lower-fat patties. PMID:27621696

Laser-activated remote phosphor light engine for projection applications

NASA Astrophysics Data System (ADS)

Daniels, Martin; Mehl, Oliver; Hartwig, Ulrich

2015-09-01

Recent developments in blue emitting laser diodes enable attractive solutions in projection applications using phosphors for efficient light conversion with very high luminance levels. Various commercially available projectors incorporating this technology have entered the market in the past years. While luminous flux levels are still comparable to lamp-based systems, lifetime expectations of classical lamp systems are exceeded by far. OSRAM GmbH has been exploring this technology for several years and has introduced the PHASER® brand name (Phosphor + laser). State-of-the-art is a rotating phosphor wheel excited by blue laser diodes to deliver the necessary primary colors, either sequentially for single-imager projection engines, or simultaneously for 3-panel systems. The PHASER® technology enables flux and luminance scaling, which allows for smaller imagers and therefore cost-efficient projection solutions. The resulting overall efficiency and ANSI lumen specification at the projection screen of these systems is significantly determined by the target color gamut and the light transmission efficiency of the projection system. With increasing power and flux level demand, thermal issues, especially phosphor conversion related, dominate the opto-mechanical system design requirements. These flux levels are a great challenge for all components of an SSL-projection system (SSL:solid-state lighting). OSRAḾs PHASER® light engine platform is constantly expanded towards higher luminous flux levels as well as higher luminance levels for various applications. Recent experiments employ blue laser pump powers of multiple 100 Watts to excite various phosphors resulting in luminous flux levels of more than 40 klm.

Trait psychopathy, emotional intelligence, and criminal thinking: Predicting illegal behavior among college students.

PubMed

Fix, Rebecca L; Fix, Spencer T

2015-01-01

Research focusing on individuals high on trait psychopathy remains limited. Higher trait psychopathy is associated with lower levels of emotional intelligence and increased participation in illegal behavior. Additionally, research has confirmed significantly higher levels of criminal thinking and lower levels of empathy in the incarcerated psychopathic population. However, the relationships between trait psychopathy and criminal thinking have not been researched in the community or college population. To test for such differences, questionnaires containing relevant measures were administered to 111 college students. Results indicated that higher levels of trait psychopathy were significantly related to less caring for others, intrapersonal understanding, and general mood, and greater interpersonal functioning and stress management. Furthermore, trait psychopathy was a strong predictor of violent, property, drug, and status offenses. Power-oriented criminal thinking was also predictive of violent behaviors, and entitlement predicted property offending. Results suggest emotional intelligence is important for predicting psychopathy, and trait psychopathy is a strong predictor of all types of illegal behaviors among the non-incarcerated population. Published by Elsevier Ltd.

Flight Investigation of Effects of Transition, Landing Approaches, Partial-Power Vertical Descents, and Droop-Stop Pounding on the Bending and Torsional Moments Encountered by a Helicopter Rotor Blade

NASA Technical Reports Server (NTRS)

Ludi, LeRoy H.

1959-01-01

Flight tests have been conducted with a single-rotor helicopter, one blade of which was equipped at 14 percent and 40 percent of the blade radius with strain gages calibrated to measure moments rather than stresses, to determine the effects of transition, landing approaches, and partial-power vertical descents on the rotor-blade bending and torsional moments. In addition, ground tests were conducted to determine the effects of static droop-stop pounding on the rotor-blade moments. The results indicate that partial-power vertical descents and landing approaches produce rotor-blade moments that are higher than the moments encountered in any other flight condition investigated to date with this equipment. Decelerating through the transition region in level flight was found to result in higher vibratory moments than accelerating through this region. Deliberately induced static droop-stop pounding produced flapwise bending moments at the 14-percent-radius station which were as high as the moments experienced in landing approaches and partial-power vertical descents.

Weld defect identification in friction stir welding using power spectral density

NASA Astrophysics Data System (ADS)

Das, Bipul; Pal, Sukhomay; Bag, Swarup

2018-04-01

Power spectral density estimates are powerful in extraction of useful information retained in signal. In the current research work classical periodogram and Welch periodogram algorithms are used for the estimation of power spectral density for vertical force signal and transverse force signal acquired during friction stir welding process. The estimated spectral densities reveal notable insight in identification of defects in friction stir welded samples. It was observed that higher spectral density against each process signals is a key indication in identifying the presence of possible internal defects in the welded samples. The developed methodology can offer preliminary information regarding presence of internal defects in friction stir welded samples can be best accepted as first level of safeguard in monitoring the friction stir welding process.

Variation of antioxidant activity and the levels of bioactive compounds in lipophilic and hydrophilic extracts from hot pepper (Capsicum spp.) cultivars.

PubMed

Bae, Haejin; Jayaprakasha, G K; Jifon, John; Patil, Bhimanagouda S

2012-10-15

Peppers (Capsicum spp.) are a rich source of diverse bioactive compounds with potential health-promoting properties. This study investigated the extraction efficiency of five solvents on antioxidant activities from cayenne (CA408 and Mesilla), jalapeño (Ixtapa) and serrano (Tuxtlas) pepper cultivars. Freeze-dried peppers were extracted using a Soxhlet extractor with five solvents: hexane, ethyl acetate, acetone, methanol, and methanol:water (80:20). The levels of specific bioactive compounds (phenolics, capsaicinoids, carotenoids and flavonoids) were determined by HPLC and antioxidant activities were assayed by three methods. For all pepper cultivars tested, hexane extracts had the highest levels of capsaicinoids and carotenoids, but methanol extracts had the maximum levels of flavonoids. Hexane extracts showed higher 2,2-diphenyl-1-pricrylhydrozyl (DPPH) radical-scavenging activity and higher reducing power, and acetone extracts (from Mesilla pepper) had a high reducing power. All pepper extracts, except hexane, were effective in preventing deoxyribose degradation, and the inhibition was increased by high concentrations of extracts. The results of the present study indicated that, among the different measures of antioxidant activity, DPPH radical-scavenging activity was strongly correlated with total bioactive compounds (capsaicinoids, carotenoids, flavonoids and total phenolics) in pepper cultivars. Copyright © 2012 Elsevier Ltd. All rights reserved.

The Influence of Chitosan Substrate and Its Nanometric Form Toward the Green Power Generation in Sediment Microbial Fuel Cell.

PubMed

Karthikeyan, C; Sathishkumar, Y; Lee, Yang Soo; Kim, Ae Rhan; Yoo, Dong Jin; Kumar, G Gnana

2017-01-01

A simple, environmental friendly and biologically important sediment interfaced fuel cell was developed for the green energy generation. The soil sediment used for the study is enriched of rich anthropogenic free organic carbon, sufficient manganese and high level potassium contents as evidenced from the geochemical characterizations. The saccharides produced by the catalytic reaction of substrate chitosan were utilized for the growth of microorganisms and electron shuttling processes. Chitosan substrate influenced sediment microbial fuel cells exhibited the nearly two fold power increment over the substrate free fuel cells. The fuel cell efficiencies were further increased by bringing the substrate chitosan at nanometric level, which is nearly three and two fold higher than that of substrate free and chitosan influenced sediment microbial fuel cells, respectively, and the influential parameters involved in the power and longevity issues were addressed with different perspectives.

Honeybees and honey as monitors for heavy metal contamination near thermal power plants in Mugla, Turkey.

PubMed

Silici, Sibel; Uluozlu, Ozgur Dogan; Tuzen, Mustafa; Soylak, Mustafa

2016-03-01

In the present work, 6 honeydew samples of known geographical and botanical origins and 11 honeybee samples were analyzed to detect possible contamination by the thermoelectric power plants in Mugla, Turkey. The contents of trace elements were determined by atomic absorption spectrometry after application of microwave digestion. The samples from the thermal power plants, which were 10-22 km away from the hives, that did not cause pollution in honeydew honeys were also analyzed. The levels of copper, cadmium (Cd), lead (Pb), zinc, manganese, iron, chromium, nickel, and aluminum were similar to the values found in other recent studies in literature. However, it was found that the contamination levels of the toxic elements such as Pb and Cd in honeybee samples measured relatively higher than that of honey samples. The study concludes that honeybees may be better bioindicators of heavy metal pollution than honey. © The Author(s) 2013.

High Voltage Design Concepts for Launch Vehicles and Orbital Spacecraft Applications

NASA Technical Reports Server (NTRS)

Hall, David K.; Kirkici, Hulya; Hillard, G. Barry; Schweickart, Daniel; Dunbar, Bill

2000-01-01

With the advent of design concepts such as, electromechanical actuation and "more electric" initiatives, has come the need for electrical power buses and electronic equipment to operate at higher than normal dc voltages to meet power requirements while keeping current levels to manageable levels. This new bus voltage has been typically 270 Volts dc nominal for launch vehicles, and 120 Volt dc for the International Space Station. This paper will discuss the new design applications for high voltage dc power in existing and future launch vehicles and spacecraft and the potential problems associated therewith. These new applications must be operational from lift-off, ascent, on orbit and descent in all of the pressure and temperature conditions for each, i.e. through the "Paschen region" twice. This paper will also attempt to stimulate an interest in the academic and professional communities to support and conduct research needed for design data applicable to high voltage dc usage.

Exhaust emission calibration of two J-58 afterburning turbojet engines at simulated high-altitude, supersonic flight conditions

NASA Technical Reports Server (NTRS)

Holdeman, J. D.

1976-01-01

Emissions of total oxides of nitrogen, nitric oxide, unburned hydrocarbons, carbon monoxide, and carbon dioxide from two J-58 afterburning turbojet engines at simulated high-altitude flight conditions are reported. Test conditions included flight speeds from Mach 2 to 3 at altitudes from 16.0 to 23.5 km. For each flight condition exhaust measurements were made for four or five power levels, from maximum power without afterburning through maximum afterburning. The data show that exhaust emissions vary with flight speed, altitude, power level, and radial position across the exhaust. Oxides of nitrogen emissions decreased with increasing altitude and increased with increasing flight speed. Oxides of nitrogen emission indices with afterburning were less than half the value without afterburning. Carbon monoxide and hydrocarbon emissions increased with increasing altitude and decreased with increasing flight speed. Emissions of these species were substantially higher with afterburning than without.

Spectral shape deformation in inverse spin Hall voltage in Y{sub 3}Fe{sub 5}O{sub 12}|Pt bilayers at high microwave power levels

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

Lustikova, J., E-mail: lustikova@imr.tohoku.ac.jp; Shiomi, Y.; Handa, Y.

2015-02-21

We report on the deformation of microwave absorption spectra and of the inverse spin Hall voltage signals in thin film bilayers of yttrium iron garnet (YIG) and platinum at high microwave power levels in a 9.45-GHz TE{sub 011} cavity. As the microwave power increases from 0.15 to 200 mW, the resonance field shifts to higher values, and the initially Lorentzian spectra of the microwave absorption intensity as well as the inverse spin Hall voltage signals become asymmetric. The contributions from opening of the magnetization precession cone and heating of YIG cannot well reproduce the data. Control measurements of inverse spinmore » Hall voltages on thin-film YIG|Pt systems with a range of line widths underscore the role of spin-wave excitations in spectral deformation.« less

Leader & Learner

ERIC Educational Resources Information Center

Hirsh, Stephanie; Hord, Shirley M.

2008-01-01

One of the most powerful ways for principals to extend their learning is to participate in professional learning communities (PLCs), forums that are explicitly designed to convene educators for learning so that students perform at higher levels. Principals can use PLCs to their professional advantage in two significant ways: (1) by participating…

Greenhouse gas and air pollutant emission reduction potentials of renewable energy--case studies on photovoltaic and wind power introduction considering interactions among technologies in Taiwan.

PubMed

Kuo, Yu-Ming; Fukushima, Yasuhiro

2009-03-01

To achieve higher energy security and lower emission of greenhouse gases (GHGs) and pollutants, the development of renewable energy has attracted much attention in Taiwan. In addition to its contribution to the enhancement of reliable indigenous resources, the introduction of renewable energy such as photovoltaic (PV) and wind power systems reduces the emission of GHGs and air pollutants by substituting a part of the carbon- and pollutant-intensive power with power generated by methods that are cleaner and less carbon-intensive. To evaluate the reduction potentials, consequential changes in the operation of different types of existing power plants have to be taken into account. In this study, a linear mathematical programming model is constructed to simulate a power mix for a given power demand in a power market sharing a cost-minimization objective. By applying the model, the emission reduction potentials of capacity extension case studies, including the enhancement of PV and wind power introduction at different scales, were assessed. In particular, the consequences of power mix changes in carbon dioxide, nitrogen oxides, sulfur oxides, and particulates were discussed. Seasonally varying power demand levels, solar irradiation, and wind strength were taken into account. In this study, we have found that the synergetic reduction of carbon dioxide emission induced by PV and wind power introduction occurs under a certain level of additional installed capacity. Investigation of a greater variety of case studies on scenario development with emerging power sources becomes possible by applying the model developed in this study.

The direct determination of dose-to-water using a water calorimeter.

PubMed

Schulz, R J; Wuu, C S; Weinhous, M S

1987-01-01

A flexible, temperature-regulated, water calorimeter has been constructed which consists of three nested cylinders. The innermost "core" is a 10 X 10 cm right cylinder made of glass, the contents of which are isolated from the environment. It has two Teflon-washered glass valves for filling, and two thermistors are supported at the center by glass capillary tubes. Surrounding the core is a "jacket" that provides approximately 2 cm of air insulation between the core and the "shield." The shield surrounds the jacket with a 2.5-cm layer of temperature-regulated water flowing at 51/min. The core is filled with highly purified water the gas content of which is established prior to filling. Convection currents, which may be induced by dose gradients or thermistor power dissipation, are eliminated by operating the calorimeter at 4 degrees C. Depending upon the power level of the thermistors, 15-200 microW, and the insulation provided by the glass capillary tubing, the temperature of the thermistors is higher than that of the surrounding water. To minimize potential errors caused by differences between calibration curves obtained at finite power levels, the zero-power-level calibration curve obtained by extrapolation is employed. Also the calorimeter response is corrected for the change in power level, and therefore thermistor temperature, that follows the resistance change caused by irradiation. The response of the calorimeter to 4-MV x rays has been compared to that of an ionization chamber irradiated in an identical geometry.(ABSTRACT TRUNCATED AT 250 WORDS)

Identification of Hemoglobin Levels Based on Anthropometric Indices in Elderly Koreans

PubMed Central

Kim, Jong Yeol

2016-01-01

Objectives Anemia is independently and strongly associated with an increased risk of mortality in older people and is also strongly associated with obesity. The objectives of the present study were to examine the associations between the hemoglobin level and various anthropometric indices, to predict low and normal hemoglobin levels using combined anthropometric indices, and to assess differences in the hemoglobin level and anthropometric indices between Korean men and women. Methods A total of 7,156 individuals ranging in age from 53–90 years participated in this retrospective cross-sectional study. Binary logistic regression (LR) and naïve Bayes (NB) models were used to identify significant differences in the anthropometric indices between subjects with low and normal hemoglobin levels and to assess the predictive power of these indices for the hemoglobin level. Results Among all of the variables, age displayed the strongest association with the hemoglobin level in both men (p < 0.0001, odds ratio [OR] = 0.487, area under the receiver operating characteristic curve based on the LR [LR-AUC] = 0.702, NB-AUC = 0.701) and women (p < 0.0001, OR = 0.636, LR-AUC = 0.625, NB-AUC = 0.624). Among the anthropometric indices, weight and body mass index (BMI) were the best predictors of the hemoglobin level. The predictive powers of all of the variables were higher in men than in women. The AUC values for the NB-Wrapper and LR-Wrapper predictive models generated using combined anthropometric indices were 0.734 and 0.723, respectively, for men and 0.649 and 0.652, respectively, for women. The use of combined anthropometric indices may improve the predictive power for the hemoglobin level. Discussion Among the various anthropometric indices, with the exception of age, we did not identify any indices that were better predictors than weight and BMI for low and normal hemoglobin levels. In addition, none of the ratios between pairs of indices were good indicators of the hemoglobin level. Finally, the Korean men tended to have higher associations between the anthropometric indices and anemia than the women. PMID:27812118

PHEV-EV Charger Technology Assessment with an Emphasis on V2G Operation

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

Kisacikoglu, Mithat C; Bedir, Abdulkadir; Ozpineci, Burak

2012-03-01

More battery powered electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs) will be introduced to the market in 2011 and beyond. Since these vehicles have large batteries that need to be charged from an external power source or directly from the grid, their batteries, charging circuits, charging stations/infrastructures, and grid interconnection issues are garnering more attention. This report summarizes information regarding the batteries used in PHEVs, different types of chargers, charging standards and circuits, and compares different topologies. Furthermore, it includes a list of vehicles that are going to be in the market soon with information on their chargingmore » and energy storage equipment. A summary of different standards governing charging circuits and charging stations concludes the report. There are several battery types that are available for PHEVs; however, the most popular ones have nickel metal hydride (NiMH) and lithium-ion (Li-ion) chemistries. The former one is being used in current hybrid electric vehicles (HEVs), but the latter will be used in most of the PHEVs and EVs due to higher energy densities and higher efficiencies. The chargers can be classified based on the circuit topologies (dedicated or integrated), location of the charger (either on or off the vehicle), connection (conductive, inductive/wireless, and mechanical), electrical waveform (direct current (dc) or alternating current (ac)), and the direction of power flow (unidirectional or bidirectional). The first PHEVs typically will have dedicated, on-board, unidirectional chargers that will have conductive connections to the charging stations or wall outlets and will be charged using either dc or ac. In the near future, bidirectional chargers might also be used in these vehicles once the benefits of practical vehicle to grid applications are realized. The terms charger and charging station cause terminology confusion. To prevent misunderstandings, a more descriptive term of electric vehicle supply equipment (EVSE) is used instead of charging station. The charger is the power conversion equipment that connects the battery to the grid or another power source, while EVSE refers to external equipment between the grid or other power source and the vehicle. EVSE might include conductors, connectors, attachment plugs, microprocessors, energy measurement devices, transformers, etc. Presently, there are more than 40 companies that are producing EVSEs. There are several standards and codes regarding conductive and inductive chargers and EVSEs from the Society of Automotive Engineers (SAE), the Underwriter Laboratories (UL), the International Electrotechnical Commission (IEC), and the National Electric Code (NEC). The two main standards from SAE describe the requirements for conductive and inductive coupled chargers and the charging levels. For inductive coupled charging, three levels are specified: Level 1 (120 V and 12 A, single-phase), Level 2 (208 V-240 V and 32 A, single-phase), and Level 3 (208-600 V and 400 A, three-phase) . The standard for the conductive-coupled charger also has similar charging ratings for Levels 1 and 2, but it allows higher current ratings for Level 2 charging up to 80 A. Level 3 charging for this standard is still under development and considers dc charging instead of three-phase ac. More details in these areas and related references can be found in this Oak Ridge National Laboratory (ORNL) report on PHEV-EV charger technology assessment.« less

Power electronics for low power arcjets

NASA Technical Reports Server (NTRS)

Hamley, John A.; Hill, Gerald M.

1991-01-01

In anticipation of the needs of future light-weight, low-power spacecraft, arcjet power electronics in the 100 to 400 W operating range were developed. Limited spacecraft power and thermal control capacity of these small spacecraft emphasized the need for high efficiency. Power topologies similar to those in the higher 2 kW and 5 to 30 kW power range were implemented, including a four transistor bridge switching circuit, current mode pulse-width modulated control, and an output current averaging inductor with an integral pulse generation winding. Reduction of switching transients was accomplished using a low inductance power distribution network, and no passive snubber circuits were necessary for power switch protection. Phase shift control of the power bridge was accomplished using an improved pulse width modulation to phase shift converter circuit. These features, along with conservative magnetics designs allowed power conversion efficiencies of greater than 92.5 percent to be achieved into resistive loads over the entire operating range of the converter. Electromagnetic compatibility requirements were not considered in this work, and control power for the converter was derived from AC mains. Addition of input filters and control power converters would result in an efficiency of on the order of 90 percent for a flight unit. Due to the developmental nature of arcjet systems at this power level, the exact nature of the thruster/power processor interface was not quantified. Output regulation and current ripple requirements of 1 and 20 percent respectively, as well as starting techniques, were derived from the characteristics of the 2 kW system but an open circuit voltage in excess of 175 V was specified. Arcjet integration tests were performed, resulting in successful starts and stable arcjet operation at power levels as low as 240 W with simulated hydrazine propellants.

Optimal Battery Utilization Over Lifetime for Parallel Hybrid Electric Vehicle to Maximize Fuel Economy

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

Patil, Chinmaya; Naghshtabrizi, Payam; Verma, Rajeev

This paper presents a control strategy to maximize fuel economy of a parallel hybrid electric vehicle over a target life of the battery. Many approaches to maximizing fuel economy of parallel hybrid electric vehicle do not consider the effect of control strategy on the life of the battery. This leads to an oversized and underutilized battery. There is a trade-off between how aggressively to use and 'consume' the battery versus to use the engine and consume fuel. The proposed approach addresses this trade-off by exploiting the differences in the fast dynamics of vehicle power management and slow dynamics of batterymore » aging. The control strategy is separated into two parts, (1) Predictive Battery Management (PBM), and (2) Predictive Power Management (PPM). PBM is the higher level control with slow update rate, e.g. once per month, responsible for generating optimal set points for PPM. The considered set points in this paper are the battery power limits and State Of Charge (SOC). The problem of finding the optimal set points over the target battery life that minimize engine fuel consumption is solved using dynamic programming. PPM is the lower level control with high update rate, e.g. a second, responsible for generating the optimal HEV energy management controls and is implemented using model predictive control approach. The PPM objective is to find the engine and battery power commands to achieve the best fuel economy given the battery power and SOC constraints imposed by PBM. Simulation results with a medium duty commercial hybrid electric vehicle and the proposed two-level hierarchical control strategy show that the HEV fuel economy is maximized while meeting a specified target battery life. On the other hand, the optimal unconstrained control strategy achieves marginally higher fuel economy, but fails to meet the target battery life.« less

Impacts of the Fukushima nuclear power plants on marine radioactivity.

PubMed

Buesseler, Ken; Aoyama, Michio; Fukasawa, Masao

2011-12-01

The impacts on the ocean of releases of radionuclides from the Fukushima Dai-ichi nuclear power plants remain unclear. However, information has been made public regarding the concentrations of radioactive isotopes of iodine and cesium in ocean water near the discharge point. These data allow us to draw some basic conclusions about the relative levels of radionuclides released which can be compared to prior ocean studies and be used to address dose consequences as discussed by Garnier-Laplace et al. in this journal. The data show peak ocean discharges in early April, one month after the earthquake and a factor of 1000 decrease in the month following. Interestingly, the concentrations through the end of July remain higher than expected implying continued releases from the reactors or other contaminated sources, such as groundwater or coastal sediments. By July, levels of (137)Cs are still more than 10,000 times higher than levels measured in 2010 in the coastal waters off Japan. Although some radionuclides are significantly elevated, dose calculations suggest minimal impact on marine biota or humans due to direct exposure in surrounding ocean waters, though considerations for biological uptake and consumption of seafood are discussed and further study is warranted.

Biomass "Green" Power Vs. Coal "Traditional" Power: Who is the Largest Emitter in Humboldt County and How Should Regulations be Addressed?

NASA Astrophysics Data System (ADS)

Zurawski, A. M.

2016-12-01

The objective of this research is to study how emissions from a fossil fuel power plant compare to emissions from a biomass power plant, and how these results can be used to improve current air-quality regulations. Outdoor air quality transcends national and political boundaries. Air pollution monitoring is essential to maintaining quality of life for humans and ecosystems. Due to anthropogenic disturbances (primarily related to burning of fossil fuels), air- quality management has become a priority on a long list of environmental issues. Quantifying and monitoring the largest emitters of greenhouse gases and toxic pollutants is crucial to the creation and enforcement of appropriate environmental protection regulations. Emissions data were collected from January 2010 to January 2016 from sensors installed close to a biomass power plant, and sensors installed close to a fossil fuel and natural gas power plant, in Humboldt County, California. In Humboldt County, where air quality serves as a baseline of air pollution in the United States, data showed that the "green" biomass power plant emitted higher levels of particulate matter compared to the fossil fuel power plant. Additionally, the biomass power plant showed levels of CO2, NOx, and SO2 emissions that suggest its place as a "green" power source should be reconsidered. Our research suggests that regulations need to be reconsidered given the potential for high pollutant emissions from biomass plants.

Estimating the vibration level of an L-shaped beam using power flow techniques

NASA Technical Reports Server (NTRS)

Cuschieri, J. M.; Mccollum, M.; Rassineux, J. L.; Gilbert, T.

1986-01-01

The response of one component of an L-shaped beam, with point force excitation on the other component, is estimated using the power flow method. The transmitted power from the source component to the receiver component is expressed in terms of the transfer and input mobilities at the excitation point and the joint. The response is estimated both in narrow frequency bands, using the exact geometry of the beams, and as a frequency averaged response using infinite beam models. The results using this power flow technique are compared to the results obtained using finite element analysis (FEA) of the L-shaped beam for the low frequency response and to results obtained using statistical energy analysis (SEA) for the high frequencies. The agreement between the FEA results and the power flow method results at low frequencies is very good. SEA results are in terms of frequency averaged levels and these are in perfect agreement with the results obtained using the infinite beam models in the power flow method. The narrow frequency band results from the power flow method also converge to the SEA results at high frequencies. The advantage of the power flow method is that detail of the response can be retained while reducing computation time, which will allow the narrow frequency band analysis of the response to be extended to higher frequencies.

A surprising exception. Himachal's success in promoting female education.

PubMed

Dreze, J

1999-01-01

Gender inequalities in India are derived partly from the economic dependence of women on men. Low levels of formal education among women reinforce the asymmetry of power between the sexes. A general pattern of sharp gender bias in education levels is noted in most Indian states; however, in the small state of Himachal Pradesh, school participation rates are almost as high for girls as for boys. Rates of school participation for girls at the primary level is close to universal in this state, and while gender bias persists at higher levels of education, it is much lower than elsewhere in India and rapidly declining. This was not the case 50 years ago; educational levels in Himachal Pradesh were no higher than in Bihar or Uttar Pradesh. Today, the spectacular transition towards universal elementary education in Himachal Pradesh has contributed to the impressive reduction of poverty, mortality, illness, undernutrition, and related deprivations.

Overexpressing Ferredoxins in Chlamydomonas reinhardtii Increase Starch and Oil Yields and Enhance Electric Power Production in a Photo Microbial Fuel Cell

PubMed Central

Huang, Li-Fen; Lin, Ji-Yu; Pan, Kui-You; Huang, Chun-Kai; Chu, Ying-Kai

2015-01-01

Ferredoxins (FDX) are final electron carrier proteins in the plant photosynthetic pathway, and function as major electron donors in diverse redox-driven metabolic pathways. We previously showed that overexpression of a major constitutively expressed ferredoxin gene PETF in Chlamydomonas decreased the reactive oxygen species (ROS) level and enhanced tolerance to heat stress. In addition to PETF, an endogenous anaerobic induced FDX5 was overexpressed in transgenic Chlamydomonas lines here to address the possible functions of FDX5. All the independent FDX transgenic lines showed decreased cellular ROS levels and enhanced tolerance to heat and salt stresses. The transgenic Chlamydomonas lines accumulated more starch than the wild-type line and this effect increased almost three-fold in conditions of nitrogen depletion. Furthermore, the lipid content was higher in the transgenic lines than in the wild-type line, both with and without nitrogen depletion. Two FDX-overexpressing Chlamydomonas lines were assessed in a photo microbial fuel cell (PMFC); power density production by the transgenic lines was higher than that of the wild-type cells. These findings suggest that overexpression of either PETF or FDX5 can confer tolerance against heat and salt stresses, increase starch and oil production, and raise electric power density in a PMFC. PMID:26287179

On the bispectra of very massive tracers in the Effective Field Theory of Large-Scale Structure

DOE PAGES

Nadler, Ethan O.; Perko, Ashley; Senatore, Leonardo

2018-02-01

The Effective Field Theory of Large-Scale Structure (EFTofLSS) provides a consistent perturbative framework for describing the statistical distribution of cosmological large-scale structure. In a previous EFTofLSS calculation that involved the one-loop power spectra and tree-level bispectra, it was shown that the k-reach of the prediction for biased tracers is comparable for all investigated masses if suitable higher-derivative biases, which are less suppressed for more massive tracers, are added. However, it is possible that the non-linear biases grow faster with tracer mass than the linear bias, implying that loop contributions could be the leading correction to the bispectra. To check this,more » we include the one-loop contributions in a fit to numerical data in the limit of strongly enhanced higher-order biases. Here, we show that the resulting one-loop power spectra and higher-derivative plus leading one-loop bispectra fit the two- and three-point functions respectively up to k≃0.19 h Mpc -1 and ksime 0.14 h Mpc -1 at the percent level. We find that the higher-order bias coefficients are not strongly enhanced, and we argue that the gain in perturbative reach due to the leading one-loop contributions to the bispectra is relatively small. Thus, we conclude that higher-derivative biases provide the leading correction to the bispectra for tracers of a very wide range of masses.« less

On the bispectra of very massive tracers in the Effective Field Theory of Large-Scale Structure

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

Nadler, Ethan O.; Perko, Ashley; Senatore, Leonardo

The Effective Field Theory of Large-Scale Structure (EFTofLSS) provides a consistent perturbative framework for describing the statistical distribution of cosmological large-scale structure. In a previous EFTofLSS calculation that involved the one-loop power spectra and tree-level bispectra, it was shown that the k-reach of the prediction for biased tracers is comparable for all investigated masses if suitable higher-derivative biases, which are less suppressed for more massive tracers, are added. However, it is possible that the non-linear biases grow faster with tracer mass than the linear bias, implying that loop contributions could be the leading correction to the bispectra. To check this,more » we include the one-loop contributions in a fit to numerical data in the limit of strongly enhanced higher-order biases. Here, we show that the resulting one-loop power spectra and higher-derivative plus leading one-loop bispectra fit the two- and three-point functions respectively up to k≃0.19 h Mpc -1 and ksime 0.14 h Mpc -1 at the percent level. We find that the higher-order bias coefficients are not strongly enhanced, and we argue that the gain in perturbative reach due to the leading one-loop contributions to the bispectra is relatively small. Thus, we conclude that higher-derivative biases provide the leading correction to the bispectra for tracers of a very wide range of masses.« less

A monostable piezoelectric energy harvester for broadband low-level excitations

NASA Astrophysics Data System (ADS)

Fan, Kangqi; Tan, Qinxue; Zhang, Yiwei; Liu, Shaohua; Cai, Meiling; Zhu, Yingmin

2018-03-01

This letter presents a monostable piezoelectric energy harvester (PEH) for achieving enhanced energy extraction from low-level excitations. The proposed PEH is realized by introducing symmetric magnetic attraction to a piezoelectric cantilever beam and a pair of stoppers to confine the maximum deflection of the beam. The lumped parameter model of such a system is presented and experimentally validated. Theoretical simulations and experimental measurements demonstrate that the proposed design can bring about a wider operating bandwidth and higher output voltage than the linear PEH. Under a sinusoidal vibration with an amplitude of 3 m/s2, a 54% increase in the operating bandwidth and a 253% increase in the magnitude of output power are achieved compared to its linear counterpart. Moreover, the proposed PEH exhibits rich dynamic features, including the tunable operating bandwidth, adjustable voltage and power levels, and softening hysteresis.

Using Conversation Topics for Predicting Therapy Outcomes in Schizophrenia

PubMed Central

Howes, Christine; Purver, Matthew; McCabe, Rose

2013-01-01

Previous research shows that aspects of doctor-patient communication in therapy can predict patient symptoms, satisfaction and future adherence to treatment (a significant problem with conditions such as schizophrenia). However, automatic prediction has so far shown success only when based on low-level lexical features, and it is unclear how well these can generalize to new data, or whether their effectiveness is due to their capturing aspects of style, structure or content. Here, we examine the use of topic as a higher-level measure of content, more likely to generalize and to have more explanatory power. Investigations show that while topics predict some important factors such as patient satisfaction and ratings of therapy quality, they lack the full predictive power of lower-level features. For some factors, unsupervised methods produce models comparable to manual annotation. PMID:23943658

Impact of strong climate change on balancing and storage needs in a fully renewable energy system

NASA Astrophysics Data System (ADS)

Weber, Juliane; Wohland, Jan; Witthaut, Dirk

2017-04-01

We investigate the impact of strong climate change on a European energy system dominated by wind power. No robust trend can be observed regarding the change of the wind power yield for most countries in Europe. However, intra-annual variabilities in wind power generation robustly increase in most of Central and Western Europe and decrease in Spain, Portugal and Greece by the end of this century. Thus, the generation of wind power tends to increase (decrease) in the winter months compared to the summer months. Due to higher (lower) intra-annual variations, the probability for extreme events with long periods of low power production increases (decreases) in summer. This implies that more (less) energy has to be provided by backup power plants. Our simulations are based on the results of five different Global Climate Models (GCMs) using the Representative Concentration Pathway scenario 8.5 (RCP8.5). These results are dynamically downscaled with the regional atmospheric model RCA4 by the EURO-CORDEX initiative (Coordinated Downscaling Experiment - European Domain). A comparison was made between historical data (1970-2000) and mid-century (2030-2060) and end-of-century (2070-2100) data, respectively. For all timeframes we made the assumption that a certain amount of energy is provided by wind power plants. This implies that changes in wind power potentials are neglected and only temporal effects are considered. Wind speed time series are converted to power generation time series using an extrapolation to hub height and a standardized power curve. Assuming a scenario for the future distribution of wind turbines, we obtain a wind power generation time series aggregated on a national level. The operation of backup power plants and storage facilities is simulated on coarse scales assuming an optimal storage strategy. Backup is required whenever the storage facilities are empty. The amount of change of the backup energy depends on the storage capacity - the higher the capacity, the higher the change as long as storage capacities do not allow for multi-year storage.

Adrenal cortical response to stress at Three Mile Island.

PubMed

Schaeffer, M A; Baum, A

1984-01-01

The present study examined the relationship between biochemical, psychologic, and behavioral components of chronic stress associated with living near the damaged nuclear power plant at Three Mile Island (TMI). Relative to control subjects, TMI subjects had higher levels of urinary cortisol, which correlated significantly with urinary catecholamines, self-report of physical and mental symptoms, and decrements in task performance. Further, it was found that males had higher urinary cortisol levels than females at TMI, while at the control sites, levels of cortisol were comparable between males and females. Finally, no significant relationship between coping style and urinary cortisol was detected. Levels of stress response among TMI are residents, though significantly greater than control subjects, were within normal ranges and thus should be considered subclinical in intensity. Their persistence over 17 months, however, suggests some cause for concern.

Estimating Potential Increased Bladder Cancer Risk Due to Increased Bromide Concentrations in Sources of Disinfected Drinking Waters

EPA Science Inventory

Public water systems are increasingly facing higher bromide levels in their source waters from anthropogenic contamination through coal-fired power plants, conventional oil and gas extraction, and hydraulic fracturing. Climate change is likely to exacerbate this in coming years. ...

The Quest for Powerful Learning Environments in Higher Education

ERIC Educational Resources Information Center

Slabbert, J. A.; Gouws, D. G.

2006-01-01

An introductory course in on tertiary level inadvertently sets the scene for the demands of the corresponding profession. Unfortunately, it seems as though these courses do not prepare learners adequately to acquire the demanding professional competences required for professional success. This problem has been a subject of contention especially in…

Strategies for Teaching Fractions: Using Error Analysis for Intervention and Assessment

ERIC Educational Resources Information Center

Spangler, David B.

2011-01-01

Many students struggle with fractions and must understand them before learning higher-level math. Veteran educator David B. Spangler provides research-based tools that are aligned with NCTM and Common Core State Standards. He outlines powerful diagnostic methods for analyzing student work and providing timely, specific, and meaningful…

Low power continuous wave-laser seed irradiation effect on Moringa oleifera germination, seedling growth and biochemical attributes.

PubMed

Urva; Shafique, Hina; Jamil, Yasir; Haq, Zia Ul; Mujahid, Tamveel; Khan, Aman Ullah; Iqbal, Munawar; Abbas, Mazhar

2017-05-01

Recently, laser application in agriculture has gained much attention since plant characteristics were improved significantly in response of pre-sowing seed treatment. Pre-sowing laser seed treatment effects on germination, seedling growth and mineral profile were studied in Moringa olifera. M. olifera healthy seeds were exposed to 25, 50, 75mJ low power continuous wave laser light and grown under greenhouse conditions. The seedling growth and biochemical attributes were evaluated from 10-day-old seedlings. The germination parameters (percentage, mean germination time), vigor index, seedling growth (root length, seedling length, shoot fresh weight, root fresh weight, shoot dry weight, root dry weight) enhanced considerably. The laser energy levels used for seed irradiation showed variable effects on germination, seedling growth and mineral profile. The mineral contents were recorded to be higher in seedling raised from laser treated seeds, which were higher in roots versus shoots and leaves. The effect of laser treatment on seedling fat, nitrogen and protein content was insignificant and at higher energy level both nitrogen and protein contents decreased versus control. Results revealed that M. olifera germination, seedling growth and mineral contents were enhanced and optimum laser energy level has more acceleratory effect since at three laser energy levels the responses were significantly different. Overall the laser energy levels effect on germination and seedling growth was found in following order; 75mJ>50mJ>25mJ, where as in case of fat, protein and nitrogen contents the trend was as; 25mJ>50mJ and 75mJ. However, this technique could possibly be used to improve the M. olifera germination, seedling growth, and minerals contents where germination is low due to unfavorable conditions. Copyright © 2017 Elsevier B.V. All rights reserved.

Prediction by data mining, of suicide attempts in Korean adolescents: a national study

PubMed Central

Bae, Sung Man; Lee, Seung A; Lee, Seung-Hwan

2015-01-01

Objective This study aimed to develop a prediction model for suicide attempts in Korean adolescents. Methods We conducted a decision tree analysis of 2,754 middle and high school students nationwide. We fixed suicide attempt as the dependent variable and eleven sociodemographic, intrapersonal, and extrapersonal variables as independent variables. Results The rate of suicide attempts of the total sample was 9.5%, and severity of depression was the strongest variable to predict suicide attempt. The rates of suicide attempts in the depression and potential depression groups were 5.4 and 2.8 times higher than that of the non-depression group. In the depression group, the most powerful factor to predict a suicide attempt was delinquency, and the rate of suicide attempts in those in the depression group with higher delinquency was two times higher than in those in the depression group with lower delinquency. Of special note, the rate of suicide attempts in the depressed females with higher delinquency was the highest. Interestingly, in the potential depression group, the most impactful factor to predict a suicide attempt was intimacy with family, and the rate of suicide attempts of those in the potential depression group with lower intimacy with family was 2.4 times higher than that of those in the potential depression group with higher intimacy with family. And, among the potential depression group, middle school students with lower intimacy with family had a 2.5-times higher rate of suicide attempts than high school students with lower intimacy with family. Finally, in the non-depression group, stress level was the most powerful factor to predict a suicide attempt. Among the non-depression group, students who reported high levels of stress showed an 8.3-times higher rate of suicide attempts than students who reported average levels of stress. Discussion Based on the results, we especially need to pay attention to depressed females with higher delinquency and those with potential depression with lower intimacy with family to prevent suicide attempts in teenagers. PMID:26396521

High-Power Piezoelectric Acoustic-Electric Power Feedthru for Metal Walls

NASA Technical Reports Server (NTRS)

Bao, Xiaoqi; Biederman, Will; Sherrit, Stewart; Badescu, Mircea; Bar-Cohen, Yoseph; Jones, Christopher; Aldrich, Jack; Chang, Zensheu

2008-01-01

Piezoelectric acoustic-electric power feed-through devices transfer electric power wirelessly through a solid wall by using acoustic waves. This approach allows for the removal of holes through structures. The technology is applicable to power supply for electric equipment inside sealed containers, vacuum or pressure vessels, etc where the holes on the wall are prohibitive or result in significant performance degrade or complex designs. In the author's previous work, 100-W electric power was transferred through a metal wall by a small, simple-structure piezoelectric device. To meet requirements of higher power applications, the feasibility to transfer kilowatts level power was investigated. Pre-stressed longitudinal piezoelectric feedthru devices were analyzed by finite element model. An equivalent circuit model was developed to predict the power transfer characteristics to different electric loads. Based on the analysis results, a prototype device was designed, fabricated and a demonstration of the transmission of electric power up to 1-kW was successfully conducted. The methods to minimize the plate wave excitation on the wall were also analyzed. Both model analysis and experimental results are presented in detail in this presentation.

Effect of occupation on lipid peroxidation and antioxidant status in coal-fired thermal plant workers.

PubMed

Kaur, Sandeep; Gill, Manmeet Singh; Gupta, Kapil; Manchanda, Kc

2013-07-01

Air pollution from coal-fired power units is large and varied, and contributes to a significant number of negative environmental and health effects. Reactive oxygen species (ROS) have been implicated in the pathogenesis of coal dust-induced toxicity in coal-fired power plants. The aim of the study was to measure free radical damage and the antioxidant activity in workers exposed to varying levels of coal dust. The study population consisted of workers in coal handling unit, turbine unit, and boiler unit (n = 50 each), working in thermal power plant; and electricians (n = 50) from same department were taken as controls. Lipid peroxidation was measured by malondialdehyde (MDA) levels and antioxidant activity was determined by superoxide dismutase (SOD) and glutathione peroxidase (GPx) levels. Statistical analysis was carried out by Student's unpaired t-test. MDA levels showed significant increase (P > 0.001) in the thermal power plant workers than the electricians working in the city. The levels of SOD and GPx were significantly higher (P > 0.001) in electricians as compared to subjects working in thermal plant. Among the thermal plant workers, the coal handling unit workers showed significant increase (P > 0.001) in MDA and significant decrease in SOD and GPx than the workers of boiler and turbine unit workers. Oxidative stress due to increase in lipid peroxidation and decrease in antioxidant activity results from exposure to coal dust and coal combustion products during thermal plant activities.

Alcohol consumption and social inequality at the individual and country levels—results from an international study

PubMed Central

Kuntsche, Sandra; Gmel, Gerhard; Bloomfield, Kim

2013-01-01

Background: International comparisons of social inequalities in alcohol use have not been extensively investigated. The purpose of this study was to examine the relationship of country-level characteristics and individual socio-economic status (SES) on individual alcohol consumption in 33 countries. Methods: Data on 101 525 men and women collected by cross-sectional surveys in 33 countries of the GENACIS study were used. Individual SES was measured by highest attained educational level. Alcohol use measures included drinking status and monthly risky single occasion drinking (RSOD). The relationship between individuals’ education and drinking indicators was examined by meta-analysis. In a second step the individual level data and country data were combined and tested in multilevel models. As country level indicators we used the Purchasing Power Parity of the gross national income, the Gini coefficient and the Gender Gap Index. Results: For both genders and all countries higher individual SES was positively associated with drinking status. Also higher country level SES was associated with higher proportions of drinkers. Lower SES was associated with RSOD among men. Women of higher SES in low income countries were more often RSO drinkers than women of lower SES. The opposite was true in higher income countries. Conclusion: For the most part, findings regarding SES and drinking in higher income countries were as expected. However, women of higher SES in low and middle income countries appear at higher risk of engaging in RSOD. This finding should be kept in mind when developing new policy and prevention initiatives. PMID:22562712

Fuel Pin Behavior Under the Slow Power Ramp Transients in the CABRI-2 Experiments

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

Charpenel, Jean; Lemoine, Francette; Sato, Ikken

Slow ramp-type transient-overpower tests were performed within the framework of the international CABRI-2 experimental program. The implemented power transients of {approx}1% nominal power/s correspond to a control rod withdrawal-type accident in a liquid-metal-cooled fast breeder reactor (FBR). The analysis of the tests includes the information elements derived from the hodoscope signals, which were assessed quantitatively and supported by destructive and nondestructive posttest examinations. These tests, performed with fuels of various geometries, demonstrated the high margin to failure of such FBR fuel pins within the expected power level before the emergency reactor shutdown. At the same time, these tests performed withmore » high- and low-smear-density industrial pins led to clarification of the influence of pellet design on fuel pin behavior under high overpower condition. With the high-smear-density solid fuel pellet pin of high burnup level, the retained gaseous fission products played an important role in the solid fuel swelling, leading to clad deformation and failure at a maximum heating rate of 81 kW.m{sup -1}, which is much greater than the end-of-life (EOL) linear rating of the pin. With the low smear-density annular pellet pin, an important fuel swelling takes place, leading to degradation of the fuel thermal conductivity. This effect was detected at the power level around 73 kW.m{sup -1}, which is also much higher than the EOL value of the pin. Furthermore, the absence of clad deformation, and consequently of failure even at the power level going up to 134.7 kW.m{sup -1}, confirmed the very high margin to failure. In consequence, it was clarified that gaseous fission products have significant effects on failure threshold as well as on thermal performance during overpower condition, and such effects are significantly dependent on fuel design and power operation conditions.« less

Propagation and coherence properties of higher order partially coherent dark hollow beams in turbulence

NASA Astrophysics Data System (ADS)

Eyyuboğlu, Halil Tanyer

2008-02-01

We formulate and evaluate in terms of graphical outputs, source and receiver plane expressions, the complex degree of coherence, beam size variation and power in bucket performance for higher order partially coherent dark hollow beams propagating in turbulent atmosphere. Our formulation is able to cover square, rectangular, circular, elliptical geometries for dark hollow and flat-topped beams in one single expression. From the graphical outputs of the receiver plane, it is observed that higher order partially coherent dark hollow beams will initially develop an outer ring around a central lobe, but will eventually evolve towards a Gaussian shape as the propagation distance is extended. It is further observed that stronger turbulence levels and greater partial coherence have similar effects on beam profile. During propagation, modulus of complex degree of coherence of partially coherent dark hollow beams appears to rise above that of the source plane values, reaching as high as near unity. Beam size analysis shows that, among the types examined, (nearly) flat-topped beam experiences the least beam expansion. Power in bucket analysis indicates that lowest order square fully coherent dark beam offers the best power capturing.

Parental personality as an inner resource that moderates the impact of ecological adversity on parenting.

PubMed

Kochanska, Grazyna; Aksan, Nazan; Penney, Sara J; Boldt, Lea J

2007-01-01

Parents' personality was examined as a moderator of the impact of demographic risk on parenting in a longitudinal study (N=102 families). Parents' personality and demographic risk (i.e., education level, age, family income, and family size) were assessed when children were infants, and parents' power assertion, warmth, and positive affect were observed in naturalistic interactions 2.5 years later. Parents' personality moderated the adverse impact of demographic risk on parenting. For parents who had memories of unstable and unhappy childhood experiences and who reported low conventionality, higher risk was linked to more power assertion, but there was no such link for those parents who recalled happy childhood experiences and who embraced conventions. For both parents who lacked a sense of optimism and social trust, and for fathers who reported low conventionality, higher risk was linked to less affectively positive parenting, but there was no such link for parents who were optimistic and trusting or for fathers who were conventional. Higher risk was linked to more power assertion, but only for mothers low in Extraversion and for fathers high in Neuroticism. 2007 APA, all rights reserved

Are gender differences in upper-body power generated by elite cross-country skiers augmented by increasing the intensity of exercise?

PubMed

Hegge, Ann Magdalen; Myhre, Kenneth; Welde, Boye; Holmberg, Hans-Christer; Sandbakk, Øyvind

2015-01-01

In the current study, we evaluated the impact of exercise intensity on gender differences in upper-body poling among cross-country skiers, as well as the associated differences in aerobic capacity, maximal strength, body composition, technique and extent of training. Eight male and eight female elite skiers, gender-matched for level of performance by FIS points, carried out a 4-min submaximal, and a 3-min and 30-sec maximal all-out test of isolated upper-body double poling on a Concept2 ski ergometer. Maximal upper-body power and strength (1RM) were determined with a pull-down exercise. In addition, body composition was assessed with a DXA scan and training during the previous six months quantified from diaries. Relative to the corresponding female values (defined as 100%), the power output produced by the men was 88%, 95% and 108% higher during the submaximal, 3-min and 30-sec tests, respectively, and peak power in the pull-down strength exercise was 118% higher (all P<0.001). During the ergometer tests the work performed per cycle by the men was 97%, 102% and 91% greater, respectively, and the men elevated their cycle rate to a greater extent at higher intensities (both P<0.01). Furthermore, men had a 61% higher VO2peak, 58% higher 1RM, relatively larger upper-body mass (61% vs 56%) and reported considerably more upper-body strength and endurance training (all P<0.05). In conclusion, gender differences in upper-body power among cross-country skiers augmented as the intensity of exercise increased. The gender differences observed here are greater than those reported previously for both lower- and whole-body sports and coincided with greater peak aerobic capacity and maximal upper-body strength, relatively more muscle mass in the upper-body, and more extensive training of upper-body strength and endurance among the male skiers.

Are Gender Differences in Upper-Body Power Generated by Elite Cross-Country Skiers Augmented by Increasing the Intensity of Exercise?

PubMed Central

Hegge, Ann Magdalen; Myhre, Kenneth; Welde, Boye; Holmberg, Hans-Christer; Sandbakk, Øyvind

2015-01-01

In the current study, we evaluated the impact of exercise intensity on gender differences in upper-body poling among cross-country skiers, as well as the associated differences in aerobic capacity, maximal strength, body composition, technique and extent of training. Eight male and eight female elite skiers, gender-matched for level of performance by FIS points, carried out a 4-min submaximal, and a 3-min and 30-sec maximal all-out test of isolated upper-body double poling on a Concept2 ski ergometer. Maximal upper-body power and strength (1RM) were determined with a pull-down exercise. In addition, body composition was assessed with a DXA scan and training during the previous six months quantified from diaries. Relative to the corresponding female values (defined as 100%), the power output produced by the men was 88%, 95% and 108% higher during the submaximal, 3-min and 30-sec tests, respectively, and peak power in the pull-down strength exercise was 118% higher (all P<0.001). During the ergometer tests the work performed per cycle by the men was 97%, 102% and 91% greater, respectively, and the men elevated their cycle rate to a greater extent at higher intensities (both P<0.01). Furthermore, men had a 61% higher VO2peak, 58% higher 1RM, relatively larger upper-body mass (61% vs 56%) and reported considerably more upper-body strength and endurance training (all P<0.05). In conclusion, gender differences in upper-body power among cross-country skiers augmented as the intensity of exercise increased. The gender differences observed here are greater than those reported previously for both lower- and whole-body sports and coincided with greater peak aerobic capacity and maximal upper-body strength, relatively more muscle mass in the upper-body, and more extensive training of upper-body strength and endurance among the male skiers. PMID:26000713

High level white noise generator

DOEpatents

Borkowski, Casimer J.; Blalock, Theron V.

1979-01-01

A wide band, stable, random noise source with a high and well-defined output power spectral density is provided which may be used for accurate calibration of Johnson Noise Power Thermometers (JNPT) and other applications requiring a stable, wide band, well-defined noise power spectral density. The noise source is based on the fact that the open-circuit thermal noise voltage of a feedback resistor, connecting the output to the input of a special inverting amplifier, is available at the amplifier output from an equivalent low output impedance caused by the feedback mechanism. The noise power spectral density level at the noise source output is equivalent to the density of the open-circuit thermal noise or a 100 ohm resistor at a temperature of approximately 64,000 Kelvins. The noise source has an output power spectral density that is flat to within 0.1% (0.0043 db) in the frequency range of from 1 KHz to 100 KHz which brackets typical passbands of the signal-processing channels of JNPT's. Two embodiments, one of higher accuracy that is suitable for use as a standards instrument and another that is particularly adapted for ambient temperature operation, are illustrated in this application.

[Water-soluble anions of atmosphere on Tianwan nuclear power station].

PubMed

Zhao, Heng-Qiang; He, Ying; Zheng, Xiao-Ling; Chen, Fa-Rong; Pang, Shi-Ping; Wang, Cai-Xia; Wang, Xiao-Ru

2010-11-01

Three major water-soluble anions (Cl-, SO4(2-) and NO3-) in the atmosphere of the Tianwan nuclear power station in Lianyungang were determined by ion chromatography from June 2005 to May 2006. The results showed that the annual average concentration of Cl-, SO4(2-) and NO3- in the atmosphere of Tianwan nuclear power station was (33.12 +/- 53.63) microg x m(-3), (53.34 +/- 30.34) microg x m(-3) and (8.34 +/- 4.47) microg x m(-3), respectively. The concentrations of the three water-soluble anions showed evident trend of seasonal variation. The concentrations of Cl-, SO4(2-) reached the highest level in summer and the lowest level in winter, while the concentration of NO3- in autumn and winter was higher than those in summer and spring. Meteorological parameters such as wind direction, wind speed, temperature and relative humidity were studied and showed definite influence to the anions concentration of the atmosphere. This is the first simultaneous monitoring of corrosive anions in the atmosphere of Chinese coastal nuclear power plant, and it will provide basis for the prevention of marine atmospheric corrosion, which will ensure the safely operating of our nuclear power industry.

Age-Associated Changes in the Spectral and Statistical Parameters of Surface Electromyogram of Tibialis Anterior

PubMed Central

2016-01-01

Age-related neuromuscular change of Tibialis Anterior (TA) is a leading cause of muscle strength decline among the elderly. This study has established the baseline for age-associated changes in sEMG of TA at different levels of voluntary contraction. We have investigated the use of Gaussianity and maximal power of the power spectral density (PSD) as suitable features to identify age-associated changes in the surface electromyogram (sEMG). Eighteen younger (20–30 years) and 18 older (60–85 years) cohorts completed two trials of isometric dorsiflexion at four different force levels between 10% and 50% of the maximal voluntary contraction. Gaussianity and maximal power of the PSD of sEMG were determined. Results show a significant increase in sEMG's maximal power of the PSD and Gaussianity with increase in force for both cohorts. It was also observed that older cohorts had higher maximal power of the PSD and lower Gaussianity. These age-related differences observed in the PSD and Gaussianity could be due to motor unit remodelling. This can be useful for noninvasive tracking of age-associated neuromuscular changes. PMID:27610379

Advanced coal gasifier-fuel cell power plant systems design

NASA Technical Reports Server (NTRS)

Heller, M. E.

1983-01-01

Two advanced, high efficiency coal-fired power plants were designed, one utilizing a phosphoric acid fuel cell and one utilizing a molten carbonate fuel cell. Both incorporate a TRW Catalytic Hydrogen Process gasifier and regenerator. Both plants operate without an oxygen plant and without requiring water feed; they, instead, require makeup dolomite. Neither plant requires a shift converter; neither plant has heat exchangers operating above 1250 F. Both plants have attractive efficiencies and costs. While the molten carbonate version has a higher (52%) efficiency than the phosphoric acid version (48%), it also has a higher ($0.078/kWh versus $0.072/kWh) ten-year levelized cost of electricity. The phosphoric acid fuel cell power plant is probably feasible to build in the near term: questions about the TRW process need to be answered experimentally, such as weather it can operate on caking coals, and how effective the catalyzed carbon-dioxide acceptor will be at pilot scale, both in removing carbon dioxide and in removing sulfur from the gasifier.

The role of motivation, responsibility, and integrative complexity in crisis escalation: comparative studies of war and peace crises.

PubMed

Winter, David G

2007-05-01

Drawing on D. G. Winter's (1993) comparison of 1914 and the Cuban Missile Crisis, the author identified 8 paired crises (1 escalating to war, 1 peacefully resolved). Documents (diplomatic messages, speeches, official media commentary) from each crisis were scored for power, affiliation, and achievement motivation; text measures of responsibility and activity inhibition; and integrative complexity. Aggregated effect-size results show that war crises had significantly higher levels of power motivation and responsibility, whereas peace crises showed trends toward higher integrative complexity and achievement motivation. Follow-up analyses suggested that these results are robust with respect to both sides in a crisis, type of material scored, and historical time. The power motive results extend previous findings, but the responsibility results suggest that responsibility plays a paradoxical role in war. Future research directions are sketched, and the role of psychological content analysis in monitoring the danger of war is discussed. ((c) 2007 APA, all rights reserved).

Optimal shapes of surface-slip driven self-propelled swimmers

NASA Astrophysics Data System (ADS)

Vilfan, Andrej; Osterman, Natan

2012-11-01

If one defines the swimming efficiency of a microorganism as the power needed to move it against viscous drag, divided by the total dissipated power, one usually finds values no better than 1%. In order to find out how close this is to the theoretically achievable optimum, we first introduced a new efficiency measure at the level of a single cilium or an infinite ciliated surface and numerically determined the optimal beating patterns according to this criterion. In the following we also determined the optimal shape of a swimmer such that the total power is minimal while maintaining the volume and the swimming speed. The resulting shape depends strongly on the allowed maximum curvature. When sufficient curvature is allowed the optimal swimmer exhibits two protrusions along the symmetry axis. The results show that prolate swimmers such as Paramecium have an efficiency that is ~ 20% higher than that of a spherical body, whereas some microorganisms have shapes that allow even higher efficiency.

Study of electromagnetic radiation pollution in Jalandhar city, India

NASA Astrophysics Data System (ADS)

Basandrai, D.; Dhami, A. K.; Bedi, R. K.; Khan, S. A.

2017-07-01

Environment pollution from electromagnetic radiations emitted from cell phone towers is a new kind of health hazard, which has increase the public concern regarding the health implications of electromagnetic radiations on humans and animals. Long term consequences of these radiations are still unknown. So it become important to measure and maps the electromagnetic radiation level to analyze potential risk. The present study has been taken to estimate the RF pollution by measuring radiation power densities level near school, hospitals and old age home of Jalandhar City, India. The radiation exposure was measured using a handheld portable electrosmog meter. Results were compared with the safety guidelines issued by ICNIRP (International commission on non ionizing radiation protection) and Bio-initiative report, 2012. It has been found that the radiation exposure level in terms of power densities and corresponding specific absorption rate (SAR) are much below than ICNIRP guidelines for all schools, hospitals and old age home. But in the case of 3 schools, the results are quite alarming where the power density and SAR was found to be 79.6% and 4%, respectively higher in comparisons with safe biological limit.

Anaerobic and Aerobic Performance of Elite Female and Male Snowboarders

PubMed Central

Żebrowska, Aleksandra; Żyła, Dorota; Kania, Damian; Langfort, Józef

2012-01-01

The physiological adaptation to training is specific to the muscle activity, dominant energy system involved, muscle groups trained, as well as intensity and volume of training. Despite increasing popularity of snowboarding only little scientific data is available on the physiological characteristics of female and male competitive snowboarders. Therefore, the purpose of this study was to compare the aerobic capacity and maximal anaerobic power of elite Polish snowboarders with untrained subjects. Ten snowboarders and ten aged matched students of Physical Education performed two exercise tests. First, a 30-second Wingate test was conducted and next, a cycle ergometer exercise test with graded intensity. In the first test, peak anaerobic power, the total work, relative peak power and relative mean power were measured. During the second test, relative maximal oxygen uptake and lactate threshold were evaluated. There were no significant differences in absolute and relative maximal oxygen uptake between snowboarders and the control group. Mean maximal oxygen uptake and lactate threshold were significantly higher in men than in women. Significant differences were found between trained men and women regarding maximal power and relative maximal power. The elite snowboarders demonstrated a high level of anaerobic power. The level of relative peak power in trained women correlated negatively with maximal oxygen uptake. In conclusion, our results seem to indicate that the demanding competition program of elite snowboarders provides a significant training stimulus mainly for anaerobic power with minor changes in anaerobic performance. PMID:23487498

Characteristics and Dose Levels for Spent Reactor Fuels

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

Coates, Cameron W

2007-01-01

Current guidance considers highly radioactive special nuclear materials to be those materials that, unshielded, emit a radiation dose [rate] measured at 1 m which exceeds 100 rem/h. Smaller, less massive fuel assemblies from research reactors can present a challenge from the point of view of self protection because of their size (lower dose, easier to handle) and the desirability of higher enrichments; however, a follow-on study to cross-compare dose trends of research reactors and power reactors was deemed useful to confirm/verify these trends. This paper summarizes the characteristics and dose levels of spent reactor fuels for both research reactors andmore » power reactors and extends previous studies aimed at quantifying expected dose rates from research reactor fuels worldwide.« less

Multivariable polynomial fitting of controlled single-phase nonlinear load of input current total harmonic distortion

NASA Astrophysics Data System (ADS)

Sikora, Roman; Markiewicz, Przemysław; Pabjańczyk, Wiesława

2018-04-01

The power systems usually include a number of nonlinear receivers. Nonlinear receivers are the source of disturbances generated to the power system in the form of higher harmonics. The level of these disturbances describes the total harmonic distortion coefficient THD. Its value depends on many factors. One of them are the deformation and change in RMS value of supply voltage. A modern LED luminaire is a nonlinear receiver as well. The paper presents the results of the analysis of the influence of change in RMS value of supply voltage and the level of dimming of the tested luminaire on the value of the current THD. The analysis was made using a mathematical model based on multivariable polynomial fitting.

Why weight? Modelling sample and observational level variability improves power in RNA-seq analyses

PubMed Central

Liu, Ruijie; Holik, Aliaksei Z.; Su, Shian; Jansz, Natasha; Chen, Kelan; Leong, Huei San; Blewitt, Marnie E.; Asselin-Labat, Marie-Liesse; Smyth, Gordon K.; Ritchie, Matthew E.

2015-01-01

Variations in sample quality are frequently encountered in small RNA-sequencing experiments, and pose a major challenge in a differential expression analysis. Removal of high variation samples reduces noise, but at a cost of reducing power, thus limiting our ability to detect biologically meaningful changes. Similarly, retaining these samples in the analysis may not reveal any statistically significant changes due to the higher noise level. A compromise is to use all available data, but to down-weight the observations from more variable samples. We describe a statistical approach that facilitates this by modelling heterogeneity at both the sample and observational levels as part of the differential expression analysis. At the sample level this is achieved by fitting a log-linear variance model that includes common sample-specific or group-specific parameters that are shared between genes. The estimated sample variance factors are then converted to weights and combined with observational level weights obtained from the mean–variance relationship of the log-counts-per-million using ‘voom’. A comprehensive analysis involving both simulations and experimental RNA-sequencing data demonstrates that this strategy leads to a universally more powerful analysis and fewer false discoveries when compared to conventional approaches. This methodology has wide application and is implemented in the open-source ‘limma’ package. PMID:25925576

'Real-world' compensatory behaviour with low nicotine concentration e-liquid: subjective effects and nicotine, acrolein and formaldehyde exposure.

PubMed

Dawkins, Lynne; Cox, Sharon; Goniewicz, Maciej; McRobbie, Hayden; Kimber, Catherine; Doig, Mira; Kośmider, Leon

2018-06-07

To compare the effects of i) high versus low nicotine concentration e-liquid, ii) fixed versus adjustable power and iii) the interaction between the two on: a) vaping behaviour, b) subjective effects, c) nicotine intake, and d) exposure to acrolein and formaldehyde in e-cigarette users vaping in their everyday setting. Counterbalanced, repeated measures with four conditions: i) low nicotine (6 mg/mL)/fixed power; ii) low nicotine/adjustable power; iii) high nicotine (18 mg/mL)/fixed power; iv) high nicotine/adjustable power. London and the South East, England. Twenty experienced e-cigarette users (recruited between September 2016 and February 2017) vaped ad libitum using an eVic Supreme™ with a 'Nautilus Aspire' tank over four weeks (one week per condition). Puffing patterns (daily puff number [PN], puff duration [PD], inter-puff interval [IPI]), mL of e-liquid consumed, changes to power (where permitted), and subjective effects (urge to vape, nicotine withdrawal symptoms) were measured in each condition. Nicotine intake was measured via salivary cotinine. 3-hydroxypropylmercapturic acid (3-HPMA), a metabolite of the toxicant acrolein, and formate, a metabolite of the carcinogen formaldehyde, were measured in urine. There was a significant nicotine concentration x power interaction for PD (p<0.01). PD was longer with low nicotine/fixed power compared with i) high nicotine/fixed power (p< 0.001 and ii) low nicotine/adjustable power (p< 0.01). PN and liquid consumed were higher in the low versus high nicotine condition (main effect of nicotine, p<0.05). Urge to vape and withdrawal symptoms were lower, and nicotine intake was higher, in the high nicotine condition (main effects of nicotine: p<0.01). Whilst acrolein levels did not differ, there was a significant nicotine x power interaction for formaldehyde (p<0.05). Use of a lower nicotine concentration e-liquid may be associated with compensatory behaviour (e.g., higher number and duration of puffs) and increases in negative affect, urge to vape, and formaldehyde exposure. This article is protected by copyright. All rights reserved.

Reduced prefrontal MEG alpha-band power in mild traumatic brain injury with associated posttraumatic stress disorder symptoms.

PubMed

Popescu, Mihai; Hughes, John D; Popescu, Elena-Anda; Riedy, Gerard; DeGraba, Thomas J

2016-09-01

To determine if changes in cortical alpha-band power in patients with mild traumatic brain injury (mTBI) are associated with the severity of their post-traumatic stress disorder (PTSD) symptoms, and if injury severity and level of exposure to psychologically traumatic events are predictors of these electrophysiological changes. Resting-state magnetoencephalographic recordings were analyzed in 32 patients with mTBI. Alpha-band power was estimated for each patient in 68 cortical regions and was compared between groups of patients with low versus high PTSD symptoms severity. Participants with high PTSD symptom severity showed reduced alpha-band power bilaterally in the superior and middle frontal gyri and frontal poles, and in the left inferior frontal gyrus. Alpha-band power in bilateral middle frontal gyri and frontal poles was negatively correlated with scores reflecting symptoms of emotional numbing. Loss of consciousness (LOC) associated with mTBI and level of exposure to psychologically traumatic events were predictors of decreased prefrontal alpha-band power in some of these regions. Altered prefrontal alpha-band activity, shown to be partly explained by mTBI-related LOC, is associated with PTSD symptoms severity. Our findings will guide future studies addressing the electrophysiological mechanisms underlying a higher incidence of PTSD in patients with mTBI. Published by Elsevier Ireland Ltd.

Experimental investigation of the transverse modal instabilities onset in high power fully-aperiodic-large-pitch fiber lasers

NASA Astrophysics Data System (ADS)

Malleville, Marie-Alicia; Benoît, Aurélien; Dauliat, Romain; Leconte, Baptiste; Darwich, Dia; du Jeu, Rémi; Jamier, Raphaël.; Schwuchow, Anka; Schuster, Kay; Roy, Philippe

2018-02-01

Over the last decade, significant work has been carried out in order to increase the energy/peak power provided by fiber lasers. Indeed, new microstructured fibers with large (or very large) mode area cores (LMA) such as Distributed Mode Filtering (DMF) fibers and Large-Pitch Fibers (LPF) have been developed to address this concern. These technologies have allowed diffraction-limited emission with core diameters higher than 80 μm, and have state-of-the-art performances in terms of pulse energy or peak power while keeping an excellent spatial beam quality. Although these fibers were designed to reach high power levels while maintaining a single transverse mode propagation, power scaling becomes quickly limited by the onset of transverse modal instabilities (TMI). This effect suddenly arises when a certain average power threshold is exceeded, drastically degrading the emitted beam quality. In this work, we investigate the influence of the core dimensions and the refractive index mismatch between the active core and the background cladding material, on the TMI power threshold in rod-type Fully-Aperiodic-LPF. This fiber structure was specifically designed to enhance the higher-order modes (HOMs) delocalization out of the gain region and thus push further the onset of modal instabilities. Using a 400W pump diode at 976 nm, the power scaling, as well as the spatial beam quality and its temporal behavior were investigated in laser configuration, which theoretically provides a lower TMI power threshold than the amplifier one due to the lack of selective excitation of the fundamental mode.

ERBS fuel addendum: Pollution reduction technology program small jet aircraft engines, phase 3

NASA Technical Reports Server (NTRS)

Bruce, T. W.; Davis, F. G.; Kuhn, T. E.; Mongia, H. C.

1982-01-01

A Model TFE731-2 engine with a low emission, variable geometry combustion system was tested to compare the effects of operating the engine on Commercial Jet-A aviation turbine fuel and experimental referee broad specification (ERBS) fuels. Low power emission levels were essentially identical while the high power NOx emission indexes were approximately 15% lower with the EBRS fuel. The exhaust smoke number was approximately 50% higher with ERBS at the takeoff thrust setting; however, both values were still below the EPA limit of 40 for the Model TFE731 engine. Primary zone liner wall temperature ran an average of 25 K higher with ERBS fuel than with Jet-A. The possible adoption of broadened proprties fuels for gas turbine applications is suggested.

Clinical nutrition managers have access to sources of empowerment.

PubMed

Mislevy, J M; Schiller, M R; Wolf, K N; Finn, S C

2000-09-01

To ascertain perceived access of dietitians to power in the workplace. The conceptual framework was Kanter's theory of organizational power. The Conditions for Work Effectiveness Questionnaire was used to measure perceived access to sources of power: information, support, resources, and opportunities. Demographic data were collected to identify factors that may enhance empowerment. The questionnaire was sent to a random sample of 348 dietitians chosen from members of the Clinical Nutrition Management dietetic practice group of the American Dietetic Association. Blank questionnaires were returned by 99 (28.4%) people not working as clinical nutrition managers, which left 249 in the sample. Descriptive statistics were used to organize and summarize data. One-way analysis of variance and t tests were performed to identify differences in responses based on levels of education, work setting, and information technology skills. Usable questionnaires were received from 178 people (71.5%). On a 5-point scale, scores for access to information (mean +/- standard deviation [SD] = 3.8 +/- 0.7), opportunity (mean +/- SD = 3.6 +/- 0.7), support (mean +/- SD = 3.2 +/- 0.9), and resources (mean +/- SD = 3.1 +/- 0.8) demonstrated that clinical nutrition managers perceived themselves as having substantial access to sources of empowerment. Those having higher levels of education, working in larger hospitals, having better-developed information technology skills, and using information technology more frequently had statistically significant higher empowerment scores (P = < or = .05) than contrasting groups in each category. Clinical nutrition managers are empowered and able to assume leadership roles in today's health care settings. Their power may be enhanced by asserting more pressure to gain greater access to sources of power: support, information, resources, and opportunities.

Scaling of Yb-Fiber Frequency Combs

NASA Astrophysics Data System (ADS)

Ruehl, Axel; Marcinkevicius, Andrius; Fermann, Martin E.; Hartl, Ingmar

2010-06-01

Immediately after their introduction in 1999, femtosecond laser frequency combs revolutionized the field of precision optical frequency metrology and are key elements in many experiments. Frequency combs based on femtosecond Er-fiber lasers based were demonstrated in 2005, allowing additionally rugged, compact set-ups and reliable unattended long-term operation. The introduction of Yb-fiber technology led to an dramatic improvement in fiber-comb performance in various aspects. Low-noise Yb-fiber femtosecond oscillators enabled a reduction of relative comb tooth linewidth to the sub-Hz level as well as scaling of the fundamental comb spacings up to 1 GHz. This is beneficial for any frequency-domain comb application due to the higher power per comb-mode. Many spectroscopic applications require, however, frequency combs way beyond the wavelength range accessible with broad band laser materials, so nonlinear conversion and hence higher peak intensity is required. We demonstrated power scaling of Yb-fiber frequency combs up to 80 W average power in a strictly linear chirped-pulse amplification schemes compatible with low-noise phase control. These high-power Yb-fiber-frequency combs facilitated not only the extension to the mid-IR spectral region. When coupled to a passive enhancement cavity, the average power can be further scaled to the kW-level opening new capabilities for XUV frequency combs via high-harmonic generation. All these advances of fiber-based frequency combs will trigger many novel applications both in fundamental and applied sciences. Schibli et al., Nature Photonics 2 355 (2008). Hartl et al., MF9 in Advanced Solid-State Photonics. 2009, Optical Society of America. Ruehl et al., AWC7 in Advanced Solid-State Photonics. 2010, Optical Society of America. Adler et al., Optics Letters 34 1330 (2009). Yost et al., Nature Physics 5 815 (2009).

Cortical oscillations and entrainment in speech processing during working memory load.

PubMed

Hjortkjaer, Jens; Märcher-Rørsted, Jonatan; Fuglsang, Søren A; Dau, Torsten

2018-02-02

Neuronal oscillations are thought to play an important role in working memory (WM) and speech processing. Listening to speech in real-life situations is often cognitively demanding but it is unknown whether WM load influences how auditory cortical activity synchronizes to speech features. Here, we developed an auditory n-back paradigm to investigate cortical entrainment to speech envelope fluctuations under different degrees of WM load. We measured the electroencephalogram, pupil dilations and behavioural performance from 22 subjects listening to continuous speech with an embedded n-back task. The speech stimuli consisted of long spoken number sequences created to match natural speech in terms of sentence intonation, syllabic rate and phonetic content. To burden different WM functions during speech processing, listeners performed an n-back task on the speech sequences in different levels of background noise. Increasing WM load at higher n-back levels was associated with a decrease in posterior alpha power as well as increased pupil dilations. Frontal theta power increased at the start of the trial and increased additionally with higher n-back level. The observed alpha-theta power changes are consistent with visual n-back paradigms suggesting general oscillatory correlates of WM processing load. Speech entrainment was measured as a linear mapping between the envelope of the speech signal and low-frequency cortical activity (< 13 Hz). We found that increases in both types of WM load (background noise and n-back level) decreased cortical speech envelope entrainment. Although entrainment persisted under high load, our results suggest a top-down influence of WM processing on cortical speech entrainment. © 2018 The Authors. European Journal of Neuroscience published by Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Anomalous response of superconducting titanium nitride resonators to terahertz radiation

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

Bueno, J., E-mail: j.bueno@sron.nl; Baselmans, J. J. A; Coumou, P. C. J. J.

We present an experimental study of kinetic inductance detectors (KIDs) fabricated of atomic layer deposited TiN films and characterized at radiation frequencies of 350 GHz. The responsivity to radiation is measured and found to increase with the increase in radiation powers, opposite to what is expected from theory and observed for hybrid niobium titanium nitride/aluminium (NbTiN/Al) and all-aluminium (all-Al) KIDs. The noise is found to be independent of the level of the radiation power. The noise equivalent power improves with higher radiation powers, also opposite to what is observed and well understood for hybrid NbTiN/Al and all-Al KIDs. We suggestmore » that an inhomogeneous state of these disordered superconductors should be used to explain these observations.« less

Practical application of power conditioning to electric propulsion for passenger vehicles

NASA Technical Reports Server (NTRS)

Demerdash, N. A.; Lee, F. C.; Nehl, T. W.; Overton, B. P.

1980-01-01

A functional model 15 HP, 120 volt, 4-pole, 7600 r.p.m. samarium-cobalt permanent magnet type brushless dc motor-transistorized power conditioner unit was designed, fabricated and tested for specific use in propulsion of electric passenger vehicles. This new brushless motor system, including its power conditioner package, has a number of important advantages over existing systems such as reduced weight and volume, higher reliability, and potential for improvements in efficiencies. These advantages are discussed in this paper in light of the substantial test data collected during experimentation with the newly developed conditioner motor propulsion system. Details of the power conditioner design philosophy and particulars are given in the paper. Also, described here are the low level electronic design and operation in relation to the remainder of the system.

High power telecommunication-compatible photoconductive terahertz emitters based on plasmonic nano-antenna arrays.

PubMed

Yardimci, Nezih Tolga; Lu, Hong; Jarrahi, Mona

2016-11-07

We present a high-power and broadband photoconductive terahertz emitter operating at telecommunication optical wavelengths, at which compact and high-performance fiber lasers are commercially available. The presented terahertz emitter utilizes an ErAs:InGaAs substrate to achieve high resistivity and short carrier lifetime characteristics required for robust operation at telecommunication optical wavelengths. It also uses a two-dimensional array of plasmonic nano-antennas to offer significantly higher optical-to-terahertz conversion efficiencies compared to the conventional photoconductive emitters, while maintaining broad operation bandwidths. We experimentally demonstrate pulsed terahertz radiation over 0.1-5 THz frequency range with the power levels as high as 300  μ W. This is the highest-reported terahertz radiation power from a photoconductive emitter operating at telecommunication optical wavelengths.

High power telecommunication-compatible photoconductive terahertz emitters based on plasmonic nano-antenna arrays

PubMed Central

Yardimci, Nezih Tolga; Lu, Hong; Jarrahi, Mona

2016-01-01

We present a high-power and broadband photoconductive terahertz emitter operating at telecommunication optical wavelengths, at which compact and high-performance fiber lasers are commercially available. The presented terahertz emitter utilizes an ErAs:InGaAs substrate to achieve high resistivity and short carrier lifetime characteristics required for robust operation at telecommunication optical wavelengths. It also uses a two-dimensional array of plasmonic nano-antennas to offer significantly higher optical-to-terahertz conversion efficiencies compared to the conventional photoconductive emitters, while maintaining broad operation bandwidths. We experimentally demonstrate pulsed terahertz radiation over 0.1–5 THz frequency range with the power levels as high as 300 μW. This is the highest-reported terahertz radiation power from a photoconductive emitter operating at telecommunication optical wavelengths. PMID:27916999

Bias in discriminating very mild dementia for older adults with different levels of education in Hong Kong.

PubMed

Chang, Jianfang; Tse, Chi-Shing; Leung, Grace Tak Yu; Fung, Ada Wai Tung; Hau, Kit-Tai; Chiu, Helen Fung Kum; Lam, Linda Chiu Wa

2014-06-01

Education has a profound effect on older adults' cognitive performance. In Hong Kong, some dementia screening tasks were originally designed for developed population with, on average, higher education. We compared the screening power of these tasks for Chinese older adults with different levels of education. Community-dwelling older adults who were healthy (N = 383) and with very mild dementia (N = 405) performed the following tasks: Mini-Mental State Examination, Alzheimer's Disease Assessment Scale-Cognitive subscales, Verbal Fluency, Abstract Thinking, and Visual/Digit Span. Logistic regression was used to examine the power of these tasks to predict Clinical Dementia Rating (CDR 0.5 vs. 0). Logistic regression analysis showed that while the screening power of the total scores in all tasks was similar for high and low education groups, there were education biases in some items of these tasks. The differential screening power in high and low education groups was not identical across items in some tasks. Thus, in cognitive assessments, we should exercise great caution when using these potentially biased items for older adults with limited education.

Evaluation of an Integrated Gas-Cooled Reactor Simulator and Brayton Turbine-Generator

NASA Technical Reports Server (NTRS)

Hissam, David Andy; Stewart, Eric T.

2006-01-01

A closed-loop brayton cycle, powered by a fission reactor, offers an attractive option for generating both planetary and in-space electric power. Non-nuclear testing of this type of system provides the opportunity to safely work out integration and system control challenges for a modest investment. Recognizing this potential, a team at Marshall Space Flight Center has evaluated the viability of integrating and testing an existing gas-cooled reactor simulator and a modified commercially available, off-the-shelf, brayton turbine-generator. Since these two systems were developed independently of one another, this evaluation had to determine if they could operate together at acceptable power levels, temperatures, and pressures. Thermal, fluid, and structural analyses show that this combined system can operate at acceptable power levels and temperatures. In addition, pressure drops across the reactor simulator, although higher than desired, are also viewed as acceptable. Three potential working fluids for the system were evaluated: N2, He/Ar, and He/Xe. Other potential issues, such as electrical breakdown in the generator and the operation of the brayton foil bearings using various gas mixtures, were also investigated.

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

Baker, Kyri; Toomey, Bridget

Evolving power systems with increasing levels of stochasticity call for a need to solve optimal power flow problems with large quantities of random variables. Weather forecasts, electricity prices, and shifting load patterns introduce higher levels of uncertainty and can yield optimization problems that are difficult to solve in an efficient manner. Solution methods for single chance constraints in optimal power flow problems have been considered in the literature, ensuring single constraints are satisfied with a prescribed probability; however, joint chance constraints, ensuring multiple constraints are simultaneously satisfied, have predominantly been solved via scenario-based approaches or by utilizing Boole's inequality asmore » an upper bound. In this paper, joint chance constraints are used to solve an AC optimal power flow problem while preventing overvoltages in distribution grids under high penetrations of photovoltaic systems. A tighter version of Boole's inequality is derived and used to provide a new upper bound on the joint chance constraint, and simulation results are shown demonstrating the benefit of the proposed upper bound. The new framework allows for a less conservative and more computationally efficient solution to considering joint chance constraints, specifically regarding preventing overvoltages.« less

Greenhouse gas and air pollutant emission reduction potentials of renewable energy - case studies on photovoltaic and wind power introduction considering interactions among technologies in Taiwan

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

Yu-Ming Kuo; Yasuhiro Fukushima

2009-03-15

To achieve higher energy security and lower emission of greenhouse gases (GHGs) and pollutants, the development of renewable energy has attracted much attention in Taiwan. In addition to its contribution to the enhancement of reliable indigenous resources, the introduction of renewable energy such as photovoltaic (PV) and wind power systems reduces the emission of GHGs and air pollutants by substituting a part of the carbon- and pollutant-intensive power with power generated by methods that are cleaner and less carbon-intensive. To evaluate the reduction potentials, consequential changes in the operation of different types of existing power plants have to be takenmore » into account. In this study, a linear mathematical programming model is constructed to simulate a power mix for a given power demand in a power market sharing a cost-minimization objective. By applying the model, the emission reduction potentials of capacity extension case studies, including the enhancement of PV and wind power introduction at different scales, were assessed. In particular, the consequences of power mix changes in carbon dioxide, nitrogen oxides, sulfur oxides, and particulates were discussed. Seasonally varying power demand levels, solar irradiation, and wind strength were taken into account. In this study, we have found that the synergetic reduction of carbon dioxide emission induced by PV and wind power introduction occurs under a certain level of additional installed capacity. Investigation of a greater variety of case studies on scenario development with emerging power sources becomes possible by applying the model developed in this study. 15 refs., 8 figs., 11 tabs.« less

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

Waye, Scot

Power electronics that use high-temperature devices pose a challenge for thermal management. With the devices running at higher temperatures and having a smaller footprint, the heat fluxes increase from previous power electronic designs. This project overview presents an approach to examine and design thermal management strategies through cooling technologies to keep devices within temperature limits, dissipate the heat generated by the devices and protect electrical interconnects and other components for inverter, converter, and charger applications. This analysis, validation, and demonstration intends to take a multi-scale approach over the device, module, and system levels to reduce size, weight, and cost.

Multi-KW dc distribution system technology research study

NASA Technical Reports Server (NTRS)

Dawson, S. G.

1978-01-01

The Multi-KW DC Distribution System Technology Research Study is the third phase of the NASA/MSFC study program. The purpose of this contract was to complete the design of the integrated technology test facility, provide test planning, support test operations and evaluate test results. The subjet of this study is a continuation of this contract. The purpose of this continuation is to study and analyze high voltage system safety, to determine optimum voltage levels versus power, to identify power distribution system components which require development for higher voltage systems and finally to determine what modifications must be made to the Power Distribution System Simulator (PDSS) to demonstrate 300 Vdc distribution capability.

Effect of geometry and operating conditions on spur gear system power loss

NASA Technical Reports Server (NTRS)

Anderson, N. E.; Loewenthal, S. H.

1980-01-01

The results of an analysis of the effects of spur gear size, pitch, width, and ratio on total mesh power loss for a wide range of speeds, torques, and oil viscosities are presented. The analysis uses simple algebraic expressions to determine gear sliding, rolling, and windage losses and also incorporates an approximate ball bearing power loss expression. The analysis shows good agreement with published data. Large diameter and fine pitched gears had higher peak efficiencies but low part load efficiency. Gear efficiencies were generally greater than 98 percent except at very low torque levels. Tare (no-load) losses are generally a significant percentage of the full load loss except at low speeds.

Effect of geometry and operating conditions on spur gear system power loss

NASA Technical Reports Server (NTRS)

Anderson, N. E.; Loewenthal, S. H.

1980-01-01

The results of an analysis of the effects of spur gear size, pitch, width and ratio on total mesh power loss for a wide range of speeds, torques and oil viscosities are presented. The analysis uses simple algebraic expressions to determine gear sliding, rolling and windage losses and also incorporates an approximate ball bearing power loss expression. The analysis shows good agreement with published data. Large diameter and fine-pitched gears had higher peak efficiencies but lower part-load efficiency. Gear efficiencies were generally greater than 98 percent except at very low torque levels. Tare (no-load) losses are generally a significant percentage of the full-load loss except at low speeds.

A scheme for a high-power, low-cost transmitter for deep space applications

NASA Astrophysics Data System (ADS)

Scheffer, L. K.

2005-10-01

Applications such as planetary radars and spacecraft communications require transmitters with extremely high effective isotropic radiated power. Until now, this has been done by combining a high-power microwave source with a large reflective antenna. However, this arrangement has a number of disadvantages. It is costly, since the steerable reflector alone is quite expensive, and for spacecraft communications, the need to transmit hurts the receive performance. For planetary radars, the utilization is very low since the antenna must be shared with other applications such as radio astronomy or spacecraft communications. This paper describes a potential new way of building such transmitters with lower cost, greater versatility, higher reliability, and potentially higher power. The basic idea is a phased array with a very large number of low-power elements, built with mass production techniques that have been optimized for consumer markets. The antennas are built en mass on printed circuit boards and are driven by chips, built with consumer complementary metal-oxide-semiconductor technology, that adjust the phase of each element. Assembly and maintenance should be comparatively inexpensive since the boards need only be attached to large, flat, unmoving, ground-level infrastructure. Applications to planetary radar and spacecraft communications are examined. Although we would be unlikely to use such a facility in this way, an implication for Search for Extraterrestrial Intelligence (SETI) is that high-power beacons are easier to build than had been thought.

Daily Peak Load Forecasting of Next Day using Weather Distribution and Comparison Value of Each Nearby Date Data

NASA Astrophysics Data System (ADS)

Ito, Shigenobu; Yukita, Kazuto; Goto, Yasuyuki; Ichiyanagi, Katsuhiro; Nakano, Hiroyuki

By the development of industry, in recent years; dependence to electric energy is growing year by year. Therefore, reliable electric power supply is in need. However, to stock a huge amount of electric energy is very difficult. Also, there is a necessity to keep balance between the demand and supply, which changes hour after hour. Consequently, to supply the high quality and highly dependable electric power supply, economically, and with high efficiency, there is a need to forecast the movement of the electric power demand carefully in advance. And using that forecast as the source, supply and demand management plan should be made. Thus load forecasting is said to be an important job among demand investment of electric power companies. So far, forecasting method using Fuzzy logic, Neural Net Work, Regression model has been suggested for the development of forecasting accuracy. Those forecasting accuracy is in a high level. But to invest electric power in higher accuracy more economically, a new forecasting method with higher accuracy is needed. In this paper, to develop the forecasting accuracy of the former methods, the daily peak load forecasting method using the weather distribution of highest and lowest temperatures, and comparison value of each nearby date data is suggested.

Controlling the joint local false discovery rate is more powerful than meta-analysis methods in joint analysis of summary statistics from multiple genome-wide association studies.

PubMed

Jiang, Wei; Yu, Weichuan

2017-02-15

In genome-wide association studies (GWASs) of common diseases/traits, we often analyze multiple GWASs with the same phenotype together to discover associated genetic variants with higher power. Since it is difficult to access data with detailed individual measurements, summary-statistics-based meta-analysis methods have become popular to jointly analyze datasets from multiple GWASs. In this paper, we propose a novel summary-statistics-based joint analysis method based on controlling the joint local false discovery rate (Jlfdr). We prove that our method is the most powerful summary-statistics-based joint analysis method when controlling the false discovery rate at a certain level. In particular, the Jlfdr-based method achieves higher power than commonly used meta-analysis methods when analyzing heterogeneous datasets from multiple GWASs. Simulation experiments demonstrate the superior power of our method over meta-analysis methods. Also, our method discovers more associations than meta-analysis methods from empirical datasets of four phenotypes. The R-package is available at: http://bioinformatics.ust.hk/Jlfdr.html . eeyu@ust.hk. 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

Upgrades to the MARIA Helicon Experiment at UW-Madison

NASA Astrophysics Data System (ADS)

Green, Jonathan; Hershkowitz, Noah; Schmitz, Oliver; Severn, Greg; Winters, Victoria

2016-10-01

The MARIA helicon plasma device at UW Madison is setup to investigate the neutral particle fueling of helicon discharges. Following initial results from the 668.614nm diode laser LIF system, the active spectroscopy diagnostic suite was expanded by establishing a 1.4J pulsed Nd:YAG pumped dye laser. To verify the new laser system, a comparison of measured ion velocities near a target plate was made between the diode based and dye based LIF systems. Additionally, theory and further verification of a new technique for measuring ion velocities leveraging Zeeman splitting is presented. During a campaign with <= 750W RF power, densities in the range of 1x1018 m-3 and 2 eV electron temperature were achieved with 4.1 mTorr of argon and a magnetic field of 750G. To achieve higher densities and explore the physics of neutral depletion, the available RF power was increased from 750W to 2kW, with further expansion to 4kW on a single antenna planned. For both power levels a clear helicon mode can be reliably established and its extension increases with increasing RF power. Basic plasma characterization at the higher RF power, such as electron density vs magnetic field scans, will be presented. This work was funded by the NSF CAREER Award PHY-1455210.

System-Level Testing of the Advanced Stirling Radioisotope Generator Engineering Hardware

NASA Technical Reports Server (NTRS)

Chan, Jack; Wiser, Jack; Brown, Greg; Florin, Dominic; Oriti, Salvatore M.

2014-01-01

To support future NASA deep space missions, a radioisotope power system utilizing Stirling power conversion technology was under development. This development effort was performed under the joint sponsorship of the Department of Energy and NASA, until its termination at the end of 2013 due to budget constraints. The higher conversion efficiency of the Stirling cycle compared with that of the Radioisotope Thermoelectric Generators (RTGs) used in previous missions (Viking, Pioneer, Voyager, Galileo, Ulysses, Cassini, Pluto New Horizons and Mars Science Laboratory) offers the advantage of a four-fold reduction in Pu-238 fuel, thereby extending its limited domestic supply. As part of closeout activities, system-level testing of flight-like Advanced Stirling Convertors (ASCs) with a flight-like ASC Controller Unit (ACU) was performed in February 2014. This hardware is the most representative of the flight design tested to date. The test fully demonstrates the following ACU and system functionality: system startup; ASC control and operation at nominal and worst-case operating conditions; power rectification; DC output power management throughout nominal and out-of-range host voltage levels; ACU fault management, and system command / telemetry via MIL-STD 1553 bus. This testing shows the viability of such a system for future deep space missions and bolsters confidence in the maturity of the flight design.

Preliminary performance and life evaluations of a 2-kW arcjet

NASA Technical Reports Server (NTRS)

Morren, W. Earl; Curran, Francis M.

1991-01-01

The first results of a program to expand the operational envelope of low-power arcjets to higher specific impulse and power levels are presented. The performance of a kW-class laboratory model arcjet thruster was characterized at three mass flow rates of a 2:1 mixture of hydrogen and nitrogen at power levels ranging from 1.0 to 2.0 kW. This same thruster was then operated for a total of 300 h at a specific impulse and power level of 550 s and 2.0 kW, respectively, in three continuous 100-h sessions. Thruster operation during the three test segments was stable, and no measurable performance degradation was observed during the test series. Substantial cathode erosion was observed during an inspection following the second 100-h test segment. Most notable was the migration of material from the center of the cathode tip to a ring around a large crater. The anode sustained no significant damage during the endurance test segments. Some difficulty was encountered during start-up after disassembly and inspection following the second 100-h test segment, which caused constrictor erosion. This resulted in a reduced flow restriction and arc chamber pressure, which in turn caused a reduction in the arc impedance.

Nutrient Composition and In Vitro Antioxidant Properties of Harungana madagascariensis Stembark Extracts

PubMed Central

Antia, Bassey Sunday; Ita, Basil Nse; Udo, Uwemedimo Emmanuel

2015-01-01

Abstract The stembarks of Harungana madagascariensis were analyzed for their content of chemical constituents, antinutrients, vitamin levels, and in vitro antioxidant properties in two solvent systems. Phytochemical screening revealed higher levels of alkaloids, saponins, and flavonoids in the methanolic (MHM) extract than in the dichloromethane (DCM) extract. The methanolic extract had higher contents of minerals, vitamins, and antinutrients except K, vitamin B1, and phytic acid, respectively. Antioxidant potentials of the stembark extracts were assessed by the 1, 1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity, metal chelating activity, and ferric reducing power. The methanolic extract showed a better antioxidant activity (IC50=87.66±0.97 μg/mL) in the DPPH system. The metal chelating activity was higher in the methanolic extract (92.4% at 20 mg/mL), but lower than the control ethylenediaminetetraacetic acid (EDTA). The methanolic extract also showed greater ferric reducing power and was richer in phenolics (132.24±0.61 mgGAE/g) and flavonoids (259.05±2.85 mgQE/g). Antinutrient analysis of the extracts indicated low levels of phytic acid, oxalates, and hydrocyanides below the lethal doses. The LD50 (i.p. mice) of the extracts showed relatively low toxicity in the range 1000–1414 mg/kg. These results support the ethnomedicinal uses of this plant in the treatment of diseases related to oxidative stress and suggest that consumption of H. madagascariensis is not harmful nutritively. PMID:25785542

Nutrient Composition and In Vitro Antioxidant Properties of Harungana madagascariensis Stembark Extracts.

PubMed

Antia, Bassey Sunday; Ita, Basil Nse; Udo, Uwemedimo Emmanuel

2015-05-01

The stembarks of Harungana madagascariensis were analyzed for their content of chemical constituents, antinutrients, vitamin levels, and in vitro antioxidant properties in two solvent systems. Phytochemical screening revealed higher levels of alkaloids, saponins, and flavonoids in the methanolic (MHM) extract than in the dichloromethane (DCM) extract. The methanolic extract had higher contents of minerals, vitamins, and antinutrients except K, vitamin B1, and phytic acid, respectively. Antioxidant potentials of the stembark extracts were assessed by the 1, 1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity, metal chelating activity, and ferric reducing power. The methanolic extract showed a better antioxidant activity (IC50=87.66±0.97 μg/mL) in the DPPH system. The metal chelating activity was higher in the methanolic extract (92.4% at 20 mg/mL), but lower than the control ethylenediaminetetraacetic acid (EDTA). The methanolic extract also showed greater ferric reducing power and was richer in phenolics (132.24±0.61 mgGAE/g) and flavonoids (259.05±2.85 mgQE/g). Antinutrient analysis of the extracts indicated low levels of phytic acid, oxalates, and hydrocyanides below the lethal doses. The LD50 (i.p. mice) of the extracts showed relatively low toxicity in the range 1000-1414 mg/kg. These results support the ethnomedicinal uses of this plant in the treatment of diseases related to oxidative stress and suggest that consumption of H. madagascariensis is not harmful nutritively.

Can IGF-I polymorphism affect power and endurance athletic performance?

PubMed

Ben-Zaken, Sigal; Meckel, Yoav; Nemet, Dan; Eliakim, Alon

2013-10-01

Insulin-like growth factor-I (IGF-I) plays a key role in exercise-associated muscle growth and development. The regulatory region of the promoter of the IGF-I gene is labile, but changes in this region were studied mostly in the elderly and in relation to pathological states. C-1245T (rs35767) is a genetic variation in the promoter region of the IGF-I gene. The minor allele T was found to be associated with higher circulating IGF-I levels, and possibly with increased muscle mass. The aim of the current study was to analyze the frequency distribution of C-1245T SNP in athletic and nonathletic Israeli populations. One hundred and sixty-five athletes (78 endurance-type athletes, and 87 power-type athletes) and 159 nonathletic healthy individuals participated in the current study. Genomic DNA was extracted from peripheral EDTA treated anti-coagulated blood using a standard protocol. Genotyping of the IGF1 C-1245T polymorphism was performed using polymerase chain reaction (PCR). We found that the endurance and power athletes' allele and genotype frequencies were significantly different from those of the control group. Only 4.8% of the athletes were TT carriers, but none of the controls carried this genotype. The T allele was found to be more frequent in the top-level power athletes (international and Olympic level) compared to national level athletes, but such a difference was not found in endurance athletes. Our findings suggest a possible contribution for the relatively rare IGF-I TT genotype to endurance performance, and in particular to power sport excellence in Israeli athletes. © 2013.

Chornobyl 30 years later: Radiation, pregnancies, and developmental anomalies in Rivne, Ukraine.

PubMed

Wertelecki, Wladimir; Chambers, Christina D; Yevtushok, Lyubov; Zymak-Zakutnya, Natalya; Sosyniuk, Zoriana; Lapchenko, Serhiy; Ievtushok, Bogdana; Akhmedzhanova, Diana; Komov, Oleksandr

2017-01-01

In the 30 years since the Chornobyl nuclear power plant disaster, there is evidence of persistent levels of incorporated ionizing radiation in adults, children and pregnant women in the surrounding area. Measured levels of Cesium-137 vary by region, and may be influenced by dietary and water sources as well as proximity to nuclear power plants. Since 2000, comprehensive, population-based birth defects monitoring has been performed in selected regions of Ukraine to evaluate trends and to generate hypotheses regarding potential causes of unexplained variations in defect rates. Significantly higher rates of microcephaly, neural tube defects, and microphthalmia have been identified in selected regions of Ukraine collectively known as Polissia compared to adjacent regions collectively termed non-Polissia, and these significantly higher rates were evident particularly in the years 2000-2009. The Polissia regions have also demonstrated higher mean whole body counts of Cesium-137 compared to values in individuals residing in other non-Polissia regions. The potential causal relationship between persistent ionizing radiation pollution and selected congenital anomaly rates supports the need for a more thorough, targeted investigation of the sources of persistent ionizing radiation and the biological plausibility of a potential teratogenic effect. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Incoherent beam combining of fiber lasers by an all-fiber 7 × 1 signal combiner at a power level of 14 kW.

PubMed

Lei, Chengmin; Gu, Yanran; Chen, Zilun; Wang, Zengfeng; Zhou, Pu; Ma, Yanxing; Xiao, Hu; Leng, Jinyong; Wang, Xiaolin; Hou, Jing; Xu, Xiaojun; Chen, Jinbao; Liu, Zejin

2018-04-16

We demonstrate an all-fiber 7 × 1 signal combiner with an output core diameter of 50 μm for high power incoherent beam combining of seven self-made Yb-doped single-mode fiber lasers around a wavelength of 1080 nm and output power of 2 kW. 14.1 kW combined output power is achieved with a total transmission efficiency of higher than 98.5% and a beam quality of M 2 = 5.37, which is close to the theoretical results based on finite-difference beam propagation technique. To the best of our knowledge, this is the highest output power ever reported for all-fiber structure beam combining generation, which indicates the feasibility and potential of >10 kW high brightness incoherent beam combining based on an all-fiber signal combiner.

The Use of a 28 GHz Gyrotron for EBW Startup Experiments on MAST

NASA Astrophysics Data System (ADS)

Caughman, J. B.; Bigelow, T. S.; Diem, S. J.; Peng, Y. K. M.; Rasmussen, D. A.; Shevchenko, V.; Hawes, J.; Lloyd, B.

2009-11-01

The use of electron Bernstein waves for non-inductive plasma current startup in MAST has recently been demonstrated [1]. The injection of 100 kW at 28 GHz generated plasma currents of up to 33 kA without the use of solenoid flux, and limited solenoid assist resulted in up to 55 kA of plasma current. A higher power 28 GHz gyrotron, with power levels of up to 300 kW for 0.5 seconds, is currently being commissioned. It is being used to investigate the scaling of startup current with microwave power and power profile as a function of time. Power modulation experiments are also being explored. Gyrotron performance and experimental results will be presented. [4pt] [1] V. Shevchenko, et al., Proceedings of the 15^th Joint Workshop on ECE and ECRH, Yosimite, USA, p. 68 (2009)

Detector Powering in the 21st Century Why stay stuck with the Good old 20th Century methods?

NASA Astrophysics Data System (ADS)

Dhawan, Satish; Sumner, Richard

Future Collider Physics Detectors are envisioned with large granularity but we have a power delivery problem unless we fill a large fraction of the detector volume with copper conductors. LHC detector electronics is powered by transporting direct current over distances of 30 to 150 meters. This is how Thomas Alva Edison powered his light bulb. For example, CMS ECAL uses 50 kiloamps at 2.5 volts, supplied over a cable set with a transmission efficiency of only 30%. The transmission loss becomes waste heat in the detector that has to be removed. We have been exploring methods to transmit the DC power at higher voltage (low current), reducing to the final low voltage (high current) using DC-DC converters. These converters must operate in high magnetic fields and high radiation levels. This requires rad hard components and non-magnetic (air core) inductors.

Sexual relationship power as a mediator between dating violence and sexually transmitted infections among college women.

PubMed

Buelna, Christina; Ulloa, Emilio C; Ulibarri, Monica D

2009-08-01

This study examined relationship power as a possible mediator of the relationship between dating violence and sexually transmitted infections (STIs). The proposed mediation model was based on the theory of gender and power as well as previous research on intimate partner violence and STI risk. Survey results from a sample of 290 single, undergraduate women indicated that 85% experienced at least one form of dating violence victimization in the past year, 5.9% tested positive for an STI, and 5.2% received treatment for an STI. Results revealed that women with lower levels of sexual relationship power had higher rates of dating violence victimization and STIs; also, sexual relationship power partially mediated the relationship between dating violence victimization and STIs. Future dating violence and STI-prevention interventions targeting young women may want to use an empowerment approach to decrease their likelihood of dating violence victimization and STI risk.

Plasma Switch for High-Power Active Pulse Compressor

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

Hirshfield, Jay L.

2013-11-04

Results are presented from experiments carried out at the Naval Research Laboratory X-band magnicon facility on a two-channel X-band active RF pulse compressor that employed plasma switches. Experimental evidence is shown to validate the basic goals of the project, which include: simultaneous firing of plasma switches in both channels of the RF circuit, operation of quasi-optical 3-dB hybrid directional coupler coherent superposition of RF compressed pulses from both channels, and operation of the X-band magnicon directly in the RF pulse compressor. For incident 1.2 ?s pulses in the range 0.63 ? 1.35 MW, compressed pulses of peak powers 5.7 ?more » 11.3 MW were obtained, corresponding to peak power gain ratios of 8.3 ? 9.3. Insufficient bakeout and conditioning of the high-power RF circuit prevented experiments from being conducted at higher RF input power levels.« less

Constraints on tree-level higher order gravitational couplings in superstring theory.

PubMed

Stieberger, Stephan

2011-03-18

We consider the scattering amplitudes of five and six gravitons at tree level in superstring theory. Their power series expansions in the Regge slope α' are analyzed through the order α'(8) showing some interesting constraints on higher order gravitational couplings in the effective superstring action such as the absence of R(5) terms. Furthermore, some transcendentality constraints on the coefficients of the nonvanishing couplings are observed: the absence of zeta values of even weight through the order α'(8) like the absence of ζ(2)ζ(3)R(6) terms. Our analysis is valid for any superstring background in any space-time dimension, which allows for a conformal field theory description.

Nilsson's Power Model connecting speed and road trauma: applicability by road type and alternative models for urban roads.

PubMed

Cameron, M H; Elvik, R

2010-11-01

Nilsson (1981) proposed power relationships connecting changes in traffic speeds with changes in road crashes at various levels of injury severity. Increases in fatal crashes are related to the 4(th) power of the increase in mean speed, increases in serious casualty crashes (those involving death or serious injury) according to the 3(rd) power, and increases in casualty crashes (those involving death or any injury) according to the 2(nd) power. Increases in numbers of crash victims at cumulative levels of injury severity are related to the crash increases plus higher powers predicting the number of victims per crash. These relationships are frequently applied in OECD countries to estimate road trauma reductions resulting from expected speed reductions. The relationships were empirically derived based on speed changes resulting from a large number of rural speed limit changes in Sweden during 1967-1972. Nilsson (2004) noted that there had been very few urban speed limit changes studied to test his power model. This paper aims to test the assumption that the model is equally applicable in all road environments. It was found that the road environment is an important moderator of Nilsson's power model. While Nilsson's model appears satisfactory for rural highways and freeways, the model does not appear to be directly applicable to traffic speed changes on urban arterial roads. The evidence of monotonically increasing powers applicable to changes in road trauma at increasing injury severity levels with changes in mean speed is weak. The estimated power applicable to serious casualties on urban arterial roads was significantly less than that on rural highways, which was also significantly less than that on freeways. Alternative models linking the parameters of speed distributions with road trauma are reviewed and some conclusions reached for their use on urban roads instead of Nilsson's model. Further research is needed on the relationships between serious road trauma and urban speeds. 2010 Elsevier Ltd. All rights reserved.

EEG activity as an objective measure of cognitive load during effortful listening: A study on pediatric subjects with bilateral, asymmetric sensorineural hearing loss.

PubMed

Marsella, Pasquale; Scorpecci, Alessandro; Cartocci, Giulia; Giannantonio, Sara; Maglione, Anton Giulio; Venuti, Isotta; Brizi, Ambra; Babiloni, Fabio

2017-08-01

Deaf subjects with hearing aids or cochlear implants generally find it challenging to understand speech in noisy environments where a great deal of listening effort and cognitive load are invested. In prelingually deaf children, such difficulties may have detrimental consequences on the learning process and, later in life, on academic performance. Despite the importance of such a topic, currently, there is no validated test for the assessment of cognitive load during audiological tasks. Recently, alpha and theta EEG rhythm variations in the parietal and frontal areas, respectively, have been used as indicators of cognitive load in adult subjects. The aim of the present study was to investigate, by means of EEG, the cognitive load of pediatric subjects affected by asymmetric sensorineural hearing loss as they were engaged in a speech-in-noise identification task. Seven children (4F and 3M, age range = 8-16 years) affected by asymmetric sensorineural hearing loss (i.e. profound degree on one side, mild-to-severe degree on the other side) and using a hearing aid only in their better ear, were included in the study. All of them underwent EEG recording during a speech-in-noise identification task: the experimental conditions were quiet, binaural noise, noise to the better hearing ear and noise to the poorer hearing ear. The subjects' Speech Recognition Thresholds (SRT) were also measured in each test condition. The primary outcome measures were: frontal EEG Power Spectral Density (PSD) in the theta band and parietal EEG PSD in the alpha band, as assessed before stimulus (word) onset. No statistically significant differences were noted among frontal theta power levels in the four test conditions. However, parietal alpha power levels were significantly higher in the "binaural noise" and in the "noise to worse hearing ear" conditions than in the "quiet" and "noise to better hearing ear" conditions (p < 0.001). SRT scores were consistent with task difficulty, but did not correlate with alpha and theta power level variations. This is the first time that EEG has been applied to children with sensorineural hearing loss with the purpose of studying the cognitive load during effortful listening. Significantly higher parietal alpha power levels in two of three noisy conditions, compared to the quiet condition, are consistent with increased cognitive load. Specifically, considering the time window of the analysis (pre-stimulus), parietal alpha power levels may be a measure of cognitive functions such as sustained attention and selective inhibition. In this respect, the significantly lower parietal alpha power levels in the most challenging listening condition (i.e. noise to the better ear) may be attributed to loss of attention and to the subsequent fatigue and "withdrawal" from the task at hand. Copyright © 2017 Elsevier B.V. All rights reserved.

Alpha power increases in right parietal cortex reflects focused internal attention

PubMed Central

Benedek, Mathias; Schickel, Rainer J.; Jauk, Emanuel; Fink, Andreas; Neubauer, Aljoscha C.

2014-01-01

This study investigated the functional significance of EEG alpha power increases, a finding that is consistently observed in various memory tasks and specifically during divergent thinking. It was previously shown that alpha power is increased when tasks are performed in mind—e.g., when bottom-up processing is prevented. This study aimed to examine the effect of task-immanent differences in bottom-up processing demands by comparing two divergent thinking tasks, one intrinsically relying on bottom-up processing (sensory-intake task) and one that is not (sensory-independence task). In both tasks, stimuli were masked in half of the trials to establish conditions of higher and lower internal processing demands. In line with the hypotheses, internal processing affected performance and led to increases in alpha power only in the sensory-intake task, whereas the sensory-independence task showed high levels of task-related alpha power in both conditions. Interestingly, conditions involving focused internal attention showed a clear lateralization with higher alpha power in parietal regions of the right hemisphere. Considering evidence from fMRI studies, right-parietal alpha power increases may correspond to a deactivation of the right temporoparietal junction, reflecting an inhibition of the ventral attention network. Inhibition of this region is thought to prevent reorienting to irrelevant stimulation during goal-driven, top-down behavior, which may serve the executive function of task shielding during demanding cognitive tasks such as idea generation and mental imagery. PMID:24561034

Reducing microwave absorption with fast frequency modulation.

PubMed

Qin, Juehang; Hubler, A

2017-05-01

We study the response of a two-level quantum system to a chirp signal, using both numerical and analytical methods. The numerical method is based on numerical solutions of the Schrödinger solution of the two-level system, while the analytical method is based on an approximate solution of the same equations. We find that when two-level systems are perturbed by a chirp signal, the peak population of the initially unpopulated state exhibits a high sensitivity to frequency modulation rate. We also find that the aforementioned sensitivity depends on the strength of the forcing, and weaker forcings result in a higher sensitivity, where the frequency modulation rate required to produce the same reduction in peak population would be lower. We discuss potential applications of this result in the field of microwave power transmission, as it shows applying fast frequency modulation to transmitted microwaves used for power transmission could decrease unintended absorption of microwaves by organic tissue.

Activity affects intraspecific body-size scaling of metabolic rate in ectothermic animals.

PubMed

Glazier, Douglas Stewart

2009-10-01

Metabolic rate is commonly thought to scale with body mass (M) to the 3/4 power. However, the metabolic scaling exponent (b) may vary with activity state, as has been shown chiefly for interspecific relationships. Here I use a meta-analysis of literature data to test whether b changes with activity level within species of ectothermic animals. Data for 19 species show that b is usually higher during active exercise (mean +/- 95% confidence limits = 0.918 +/- 0.038) than during rest (0.768 +/- 0.069). This significant upward shift in b to near 1 is consistent with the metabolic level boundaries hypothesis, which predicts that maximal metabolic rate during exercise should be chiefly influenced by volume-related muscular power production (scaling as M (1)). This dependence of b on activity level does not appear to be a simple temperature effect because body temperature in ectotherms changes very little during exercise.

University Rankings, Global Models, and Emerging Hegemony: Critical Analysis from Japan

ERIC Educational Resources Information Center

Ishikawa, Mayumi

2009-01-01

The study analyzes how the emergence of dominant models in higher education and power they embody affect non-Western, non-English language universities such as those in Japan. Based on extended micro-level participant observation in a Japanese research university aspiring to become a "world-class" institution, their struggles and the…

"All Gas and No Brakes!": Helpful Metaphor or Harmful Stereotype?

ERIC Educational Resources Information Center

Payne, Monica A.

2012-01-01

Stanley Hall's (1904) description of adolescence as a time "suggestive of some ancient period of storm and stress when old moorings were broken and a higher level attained" is arguably one of developmental psychology's most vivid and powerful metaphors. Its relatively insignificant contribution to Hall's treatise (Arnett, 2006), the early demise…

An Experiment on Wind Energy

ERIC Educational Resources Information Center

Lombardo, Vincenzo; Fiordilino, Emilio; Gallitto, Aurelio Agliolo; Aglieco, Pasquale

2012-01-01

We discuss an experiment on wind energy performed with home-made apparatus. The experiment reproduces a laboratory windmill, which can pump water from a lower level to a higher one. By measuring the gain of the gravitational potential energy of the pumped water, one can determine the power extracted from the wind. The activity was carried out with…

Significance of beach geomorphology on fecal indicator bacteria levels.

PubMed

Donahue, Allison; Feng, Zhixuan; Kelly, Elizabeth; Reniers, Ad; Solo-Gabriele, Helena M

2017-08-15

Large databases of fecal indicator bacteria (FIB) measurements are available for coastal waters. With the assistance of satellite imagery, we illustrated the power of assessing data for many sites by evaluating beach features such as geomorphology, distance from rivers and canals, presence of piers and causeways, and degree of urbanization coupled with the enterococci FIB database for the state of Florida. We found that beach geomorphology was the primary characteristic associated with enterococci levels that exceeded regulatory guidelines. Beaches in close proximity to marshes or within bays had higher enterococci exceedances in comparison to open coast beaches. For open coast beaches, greater enterococci exceedances were associated with nearby rivers and higher levels of urbanization. Piers and causeways had a minimal contribution, as their effect was often overwhelmed by beach geomorphology. Results can be used to understand the potential causes of elevated enterococci levels and to promote public health. Copyright © 2017 Elsevier Ltd. All rights reserved.

Shifts in information processing level: the speed theory of intelligence revisited.

PubMed

Sircar, S S

2000-06-01

A hypothesis is proposed here to reconcile the inconsistencies observed in the IQ-P3 latency relation. The hypothesis stems from the observation that task-induced increase in P3 latency correlates positively with IQ scores. It is hypothesised that: (a) there are several parallel information processing pathways of varying complexity which are associated with the generation of P3 waves of varying latencies; (b) with increasing workload, there is a shift in the 'information processing level' through progressive recruitment of more complex polysynaptic pathways with greater processing power and inhibition of the oligosynaptic pathways; (c) high-IQ subjects have a greater reserve of higher level processing pathways; (d) a given 'task-load' imposes a greater 'mental workload' in subjects with lower IQ than in those with higher IQ. According to this hypothesis, a meaningful comparison of the P3 correlates of IQ is possible only when the information processing level is pushed to its limits.

Mechanical impedance and absorbed power of hand-arm under x(h)-axis vibration and role of hand forces and posture.

PubMed

Aldien, Yasser; Marcotte, Pierre; Rakheja, Subhash; Boileau, Paul-Emile

2005-07-01

The biodynamic responses of the hand-arm system under x(h)-axis vibration are investigated in terms of the driving point mechanical impedance (DPMI) and absorbed power in a laboratory study. For this purpose, seven healthy male subjects are exposed to two levels of random vibration in the 8-1,000 Hz frequency range, using three instrumented cylindrical handles of different diameters (30, 40 and 50 mm), and different combinations of grip (10, 30 and 50 N) and push (0, 25 and 50 N) forces. The experiments involve grasping the handle while adopting two different postures, involving elbow flexion of 90 degrees and 180 degrees, with wrist in the neutral position for both postures. The analyses of the results revealed peak DPMI magnitude and absorbed power responses near 25 Hz and 150 Hz, for majority of the test conditions considered. The frequency corresponding to the peak response increased with increasing hand forces. Unlike the absorbed power, the DPMI response was mostly observed to be insensitive to variations in the excitation magnitude. The handle diameter revealed obvious effects on the DPMI magnitude, specifically at frequencies above 250 Hz, which was not evident in the absorbed power due to relatively low velocity at higher frequencies. The influence of hand forces was also evident on the DPMI magnitude response particularly at frequencies. above 100 Hz, while the effect of hand-arm posture on the DPMI magnitude was nearly negligible. The magnitude of power absorbed within the hand and arm was observed to be strongly dependent upon the excitation level over the entire frequency range, while the influence of hand-arm posture on the total absorbed power was observed to be important. The effect of variations in the hand forces on the absorbed power was relatively small for the bent elbow posture, while an increase in either the grip or the push force coupled with the extended arm posture resulted in considerably higher energy absorption. The results suggested that the handle size, hand-arm posture and hand forces, produce coupled effect on the biodynamic response of the hand-arm system.

Differences in oxygen consumption and external power between male and female speed skaters during supramaximal cycling.

PubMed

van Ingen Schenau, G J; de Groot, G

1983-01-01

Differences in performance levels between elite male and female endurance athletes are often explained by differences found in VO2 max even when expressed in VO2 max per kilogram lean body mass (VO2/LBM). Such an explanation is only a matter of course when less or no difference exists in mechanical efficiency, anaerobic power and technical variables like friction constants between males and females. Particularly during supramaximal exercises. In this study five elite male speed skaters were compared with five elite female speed skaters with respect to oxygen consumption and external power during a 3 min supramaximal bicycle ergometer test. The training background and training history of both groups were comparable. Although the elite males showed a 20% higher VO2/BW and 8% higher VO2/LBM (71.0 versus 65.01 x min-1 . kg-1) than the females, the female group showed the same mean external power Pc per kilogram body weight, and a surprising 12% higher Pc/LBM than the males (6.47 versus 5.79 W x kg-1). Hence the female group delivered 22% more external power per liter of oxygen consumption. With the help of additional data from 14 male and 11 female sub-elite skaters it is shown that the differences between the elite groups are mainly due to sex differences. In the light of differences between men and women reported in other studies, it seems likely that the differences found in this study are due to a difference in mechanical efficiency which particularly occurs in supramaximal tasks.(ABSTRACT TRUNCATED AT 250 WORDS)

Seasonal evolution of suspended particles around a large coal-fired power station: Chemical characterization

NASA Astrophysics Data System (ADS)

Querol, Xavier; Alastuey, A´s.; Puicercus, J´A.; Mantilla, Enrique; Ruiz, Carmen R.; Lopez-Soler, Angel; Plana, Felicia`; Juan, Roberto

The present work focuses on the seasonal evolution of total suspended particles (TSP) around the Teruel power station in Northeastern Spain. The results show a marked seasonal trend, along the sampling period (July 1995-July 1996), which is characterized by levels of the elements studied in TSP that were higher (up to one order of magnitude) in spring-summer and decreased progressively towards winter. This trend contrasts with the seasonal evolution reported by most of the studies carried out in industrial and urban areas in Central and Northern Europe. The origin of this seasonal TSP trend may be related to: (a) higher summer oxidation which increased levels of secondary TSP; (b) higher convective circulation in summer which raised levels of soil-related particles and primary anthropogenic particles; (c) higher frequency of intrusion episodes of Sahara air masses in summer and spring; and (d) lower aerosol scavenging potential in summer. A clear grain-size fractionation was observed for the different ions determined. SO 42- and NH 4+ were concentrated in the finest grain-size fraction (0.3-0.6 μm); NO 3-, Cl -, K +, Mg 2+, Na + and minor amounts of NH 4+ were concentrated in the 1.2-5.0 μm fractions; and Ca 2+ increased with the particle diameter. S-bearing species were (NH 4) 2SO 4 (mascagnite), (NH 4) 2Ca(SO 4) 2 · H 2O (koktaite) and CaSO 4 · 2H 2O (gypsum). Mascagnite was the dominant species in the finest grain size fraction (0.3-0.6 μm), whereas koktaite was also present in the 0.6-1.2 μm fraction, and gypsum predominated in the other fractions.

Silicon Nanophotonics for Many-Core On-Chip Networks

NASA Astrophysics Data System (ADS)

Mohamed, Moustafa

Number of cores in many-core architectures are scaling to unprecedented levels requiring ever increasing communication capacity. Traditionally, architects follow the path of higher throughput at the expense of latency. This trend has evolved into being problematic for performance in many-core architectures. Moreover, the trends of power consumption is increasing with system scaling mandating nontraditional solutions. Nanophotonics can address these problems, offering benefits in the three frontiers of many-core processor design: Latency, bandwidth, and power. Nanophotonics leverage circuit-switching flow control allowing low latency; in addition, the power consumption of optical links is significantly lower compared to their electrical counterparts at intermediate and long links. Finally, through wave division multiplexing, we can keep the high bandwidth trends without sacrificing the throughput. This thesis focuses on realizing nanophotonics for communication in many-core architectures at different design levels considering reliability challenges that our fabrication and measurements reveal. First, we study how to design on-chip networks for low latency, low power, and high bandwidth by exploiting the full potential of nanophotonics. The design process considers device level limitations and capabilities on one hand, and system level demands in terms of power and performance on the other hand. The design involves the choice of devices, designing the optical link, the topology, the arbitration technique, and the routing mechanism. Next, we address the problem of reliability in on-chip networks. Reliability not only degrades performance but can block communication. Hence, we propose a reliability-aware design flow and present a reliability management technique based on this flow to address reliability in the system. In the proposed flow reliability is modeled and analyzed for at the device, architecture, and system level. Our reliability management technique is superior to existing solutions in terms of power and performance. In fact, our solution can scale to thousand core with low overhead.

Are Wave and Tidal Energy Plants New Green Technologies?

PubMed

Douziech, Mélanie; Hellweg, Stefanie; Verones, Francesca

2016-07-19

Wave and tidal energy plants are upcoming, potentially green technologies. This study aims at quantifying their various potential environmental impacts. Three tidal stream devices, one tidal range plant and one wave energy harnessing device are analyzed over their entire life cycles, using the ReCiPe 2008 methodology at midpoint level. The impacts of the tidal range plant were on average 1.6 times higher than the ones of hydro-power plants (without considering natural land transformation). A similar ratio was found when comparing the results of the three tidal stream devices to offshore wind power plants (without considering water depletion). The wave energy harnessing device had on average 3.5 times higher impacts than offshore wind power. On the contrary, the considered plants have on average 8 (wave energy) to 20 (tidal stream), or even 115 times (tidal range) lower impact than electricity generated from coal power. Further, testing the sensitivity of the results highlighted the advantage of long lifetimes and small material requirements. Overall, this study supports the potential of wave and tidal energy plants as alternative green technologies. However, potential unknown effects, such as the impact of turbulence or noise on marine ecosystems, should be further explored in future research.

Continuous liquid level detection based on two parallel plastic optical fibers in a helical structure

NASA Astrophysics Data System (ADS)

Zhang, Yingzi; Hou, Yulong; Zhang, Yanjun; Hu, Yanjun; Zhang, Liang; Gao, Xiaolong; Zhang, Huixin; Liu, Wenyi

2018-02-01

A simple and low-cost continuous liquid-level sensor based on two parallel plastic optical fibers (POFs) in a helical structure is presented. The change in the liquid level is determined by measuring the side-coupling power in the passive fiber. The side-coupling ratio is increased by just filling the gap between the two POFs with ultraviolet-curable optical cement, making the proposed sensor competitive. The experimental results show that the side-coupling power declines as the liquid level rises. The sensitivity and the measurement range are flexible and affected by the geometric parameters of the helical structure. A higher sensitivity of 0.0208 μW/mm is acquired for a smaller curvature radius of 5 mm, and the measurement range can be expanded to 120 mm by enlarging the screw pitch to 40 mm. In addition, the reversibility and temperature dependence are studied. The proposed sensor is a cost-effective solution offering the advantages of a simple fabrication process, good reversibility, and compensable temperature dependence.

Prevalence of traditional and novel markers of cardiovascular disease risk in Scottish adolescents: socioeconomic effects.

PubMed

Buchan, Duncan S; Ollis, Stewart; Thomas, Non-Eleri; Simpson, Alan; Young, John D; Cooper, Stephen-Mark; Malina, Robert M; Cockcroft, John R; Baker, Julien S

2012-10-01

Information on the health status and physical activity of Scottish adolescents is limited. This study examines the prevalence of cardiovascular disease (CVD) risk in Scottish adolescents by socioeconomic status (SES). Participants were recruited from two high schools that differed in the SES of the students in attendance. The sample included 73 boys and 34 girls (16.4 ± 0.6 years). Variables included anthropometry, physical activity, physical fitness, blood pressure, diet, and 11 metabolic markers of CVD risk. Significant sex differences (P ≤ 0.01) were noted for stature, waist circumference, waist-hip ratio, physical activity, cardiorespiratory fitness, muscular power, sprint speed, and several CVD risk factors: high-density lipoprotein (HDL), low-density lipoprotein (LDL), interleukin-6 (IL-6), and C-reactive protein (CRP) levels. Boys from a lower SES had significantly higher levels of glucose and plasminogen activator inhibitor-1 (PAI-1) but lower levels of adiponectin compared with boys from a higher SES. Girls from a lower SES had significantly (P ≤ 0.01) higher glucose and PAI-1 levels but lower levels of insulin and adiponectin than girls from a higher SES. High fat diets, low physical activity levels, and elevated CRP and total cholesterol levels were the CVD risk factors most commonly identified as being at-risk levels in this cohort, regardless of sex or SES. SES differences were not consistently apparent, but several CVD risk factors were identified as elevated in this sample of adolescents, regardless of sex or SES.

SRG110 Stirling Generator Dynamic Simulator Vibration Test Results and Analysis Correlation

NASA Technical Reports Server (NTRS)

Lewandowski, Edward J.; Suarez, Vicente J.; Goodnight, Thomas W.; Callahan, John

2007-01-01

The U.S. Department of Energy (DOE), Lockheed Martin (LM), and NASA Glenn Research Center (GRC) have been developing the Stirling Radioisotope Generator (SRG110) for use as a power system for space science missions. The launch environment enveloping potential missions results in a random input spectrum that is significantly higher than historical radioisotope power system (RPS) launch levels and is a challenge for designers. Analysis presented in prior work predicted that tailoring the compliance at the generator-spacecraft interface reduced the dynamic response of the system thereby allowing higher launch load input levels and expanding the range of potential generator missions. To confirm analytical predictions, a dynamic simulator representing the generator structure, Stirling convertors and heat sources were designed and built for testing with and without a compliant interface. Finite element analysis was performed to guide the generator simulator and compliant interface design so that test modes and frequencies were representative of the SRG110 generator. This paper presents the dynamic simulator design, the test setup and methodology, test article modes and frequencies and dynamic responses, and post-test analysis results. With the compliant interface, component responses to an input environment exceeding the SRG110 qualification level spectrum were all within design allowables. Post-test analysis included finite element model tuning to match test frequencies and random response analysis using the test input spectrum. Analytical results were in good overall agreement with the test results and confirmed previous predictions that the SRG110 power system may be considered for a broad range of potential missions, including those with demanding launch environments.

Inhibitory Control and Impulsivity Levels in Women Crack Users.

PubMed

Hess, Adriana Raquel Binsfeld; Menezes, Carolina B; de Almeida, Rosa Maria Martins

2018-05-12

investigate impulsivity levels and inhibitory control in women crack users and explore the relationships between impulsivity and inhibitory control. 52 healthy women (M = 32.83 years; SD = 9.54) and 46 crack cocaine users (M = 31.02 years; SD = 7.73), in abstinence, performed the assessment protocol included a Sociodemographic Data Questionnaire, Mini-Mental State Examination (MMSE), a GO/No-Go Task and the Barratt Impulsiveness Scale-11 (BIS-11). It was a quantitative research with cross-sectional design and control group. crack group showed higher levels of impulsivity in all domains when compared to the control group (crack group M = 76.39, SD = 11.39, control group M = 58.53, SD = 10.76, p <.01). Participants from the crack group presented a significantly higher total reaction time in the Go-NoGo task (F(1,93) = 9.93, p =.002; effect size =.09, observed power =.87) and significantly more commission (F(1,93) = 7.20, p =.009; effect size =.07, observed power =.75) and omission errors (F(1,93) = 6.04, p =.01; effect size =.06, observed power =.68), in Go/NoGo Task. Groups did also significantly differ on total standard deviations suggesting that variability in total reaction time was significantly greater in the crack group. Results showed that only in the crack group there were significant correlations between Go-NoGo parameters and Barratt Impulsiveness Scale. Our findings are consistent that impulsivity and inhibitory control are closely linked to crack use in women. Future studies should consider to evaluate crack users in different withdrawal times, controlling the impact of abstinence time in the variables studied.

Population impact of familial and environmental risk factors for schizophrenia: a nationwide study.

PubMed

Sørensen, Holger J; Nielsen, Philip R; Pedersen, Carsten B; Benros, Michael E; Nordentoft, Merete; Mortensen, Preben B

2014-03-01

Although several studies have examined the relative contributions of familial and environmental risk factors for schizophrenia, few have additionally examined the predictive power on the individual level and simultaneously examined the population impact associated with a wide range of familial and environmental risk factors. The authors present rate ratios (IRR), population-attributable risks (PAR) and sex-specific cumulative incidences of the following risk factors: parental history of mental illness, urban place of birth, advanced paternal age, parental loss and immigration status. We established a population-based cohort of 2,486,646million persons born in Denmark between 1 January 1955 and 31 December 1993 using Danish registers. We found that PAR associated with urban birth was 11.73%; PAR associated with one, respectively 2, parent(s) with schizophrenia was 2.67% and 0.12%. PAR associated with second-generation immigration was 0.70%. Highest cumulative incidence (CI=20.23%; 95% CI=18.10-22.62) was found in male offspring of 2 parents with schizophrenia. Cumulative incidences for male offspring or female offspring of a parent with schizophrenia were 9.53% (95% CI=7.71-11.79), and 4.89%, (95% CI 4.50-5.31). The study showed that risk factors with highest predictive power on the individual level have a relatively low population impact. The challenge in future studies with direct genetic data is to examine gene-environmental interactions that can move research beyond current approaches and seek to achieve higher predictive power on the individual level and higher population impact. Copyright © 2014 Elsevier B.V. All rights reserved.

High Efficiency Microwave Power Amplifier: From the Lab to Industry

NASA Technical Reports Server (NTRS)

Sims, William Herbert, III; Bell, Joseph L. (Technical Monitor)

2001-01-01

Since the beginnings of space travel, various microwave power amplifier designs have been employed. These included Class-A, -B, and -C bias arrangements. However, shared limitation of these topologies is the inherent high total consumption of input power associated with the generation of radio frequency (RF)/microwave power. The power amplifier has always been the largest drain for the limited available power on the spacecraft. Typically, the conversion efficiency of a microwave power amplifier is 10 to 20%. For a typical microwave power amplifier of 20 watts, input DC power of at least 100 watts is required. Such a large demand for input power suggests that a better method of RF/microwave power generation is required. The price paid for using a linear amplifier where high linearity is unnecessary includes higher initial and operating costs, lower DC-to-RF conversion efficiency, high power consumption, higher power dissipation and the accompanying need for higher capacity heat removal means, and an amplifier that is more prone to parasitic oscillation. The first use of a higher efficiency mode of power generation was described by Baxandall in 1959. This higher efficiency mode, Class-D, is achieved through distinct switching techniques to reduce the power losses associated with switching, conduction, and gate drive losses of a given transistor.

Preparing aircraft propulsion for a new era in energy and the environment

NASA Technical Reports Server (NTRS)

Stewart, W. L.; Nored, D. L.; Grobman, J. S.; Feiler, C. E.; Petrash, D. A.

1980-01-01

Improving fuel efficiency, new sources of jet fuel, and noise and emission control are subjects of NASA's aeronautics program. Projects aimed at attaining a 5% fuel savings for existing engines and a 13-22% savings for the next generation of turbofan engines using advanced components, and establishing a basis for turboprop-powered commercial air transports with 30-40% savings over conventional turbofan aircraft at comparable speeds and altitudes, are discussed. Fuel sources are considered in terms of reduced hydrogen and higher aromatic contents and resultant higher liner temperatures, and attention is given to lean burning, improved fuel atomization, higher freezing-point fuel, and deriving jet fuel from shale oil or coal. Noise sources including the fan, turbine, combustion process, and flow over internal struts, and attenuation using acoustic treatment, are discussed, while near-term reduction of polluting gaseous emissions at both low and high power, and far-term defining of the minimum gaseous-pollutant levels possible from turbine engines are also under study.

Public acceptance of nuclear power among Malaysian students

NASA Astrophysics Data System (ADS)

Muhamad Pauzi, Anas; Saad, Juniza Md; Arif Abu Bakar, Asyraf; Hannan Damahuri, Abdul; Syukri, Nur Syamim Mohd

2018-01-01

Malaysian government’s aim to include nuclear energy for electricity generation has triggered various reactions from all especially the public. The objective of this study is to have a better understanding on the knowledge, sources of information of nuclear power and sources of energy chosen by Malaysian in 20 years’ time. Besides that, we want to examine the level of acceptance and perception of Malaysian towards nuclear energy and we want to identify the correlation between public perceptions with the acceptance towards nuclear power in Malaysia, and also to study the differences between perception and acceptance of nuclear power with gender and educational level. For this research methodology, the research questions are given orally or through paper-pencil and also social networking site such as Facebook or through electronic media application such as WhatsApp and Google docs. The data were analysed using a SPSS version 22.0 (Statistical Package for the Social Sciences). Results showed that more than 50% of the respondents have the knowledge of nuclear energy. A part of from that, only 39 % are confident government can afford to build NPP in Malaysia and 41 % disagree nuclear energy is the best option for future energy. From analysis using SPSS 22 we estimate negative perception will give a negative acceptance in term of support towards the use of nuclear energy in power generation in Malaysia. There are also slight correlation that the higher the level of education of Malaysian, the more negative the perception of Malaysian in accepting nuclear energy as source of power in Malaysia. Therefore in shaping a positive acceptance of NPP in Malaysia, the authorities need to educate the people with the knowledge of nuclear in order to overcome the negative perception towards nuclear power.

The Himalayan hydro machine and space transmission power systems - An Asian dream of 21st century

NASA Astrophysics Data System (ADS)

Admoddie, M.

The advantages and disadvantages for the development of hydroelectric power are assessed for the Himalayan Rectangle, an area rising 1500 km north of a baseline between Karachi and Mandalay. This area has the potential for possessing one of the world's greatest power production capabilities. Among the disadvantages cited are the political instability and religious fundamentalism of the area, the bankrupt governments, environmental degradation, and inefficient power and irrigation systems. The advantages include the millions of talented and enterprising people in the region awaiting higher opportunities who are eager to improve their families' living standards and the large untapped hydropower resources. The concepts for hydropower development are discussed and go beyond the technologies of power and water. They include catchment ecodevelopment strategies with massive afforestation plans, setting up plans to strengthen village-level institutions to manage local natural biomass and water assets, the conversion of this regional hydropower potential into a subcontinental power system, and the exporting of power and the development of an interregional and international power grid by 2030, when both oil and local ecosystems would be dangerously depleted.

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

Hoke, Anderson; Shirazi, Mariko; Chakraborty, Sudipta

As deployment of power electronic coupled generation such as photovoltaic (PV) systems increases, grid operators have shown increasing interest in calling on inverter-coupled generation to help mitigate frequency contingency events by rapidly surging active power into the grid. When responding to contingency events, the faster the active power is provided, the more effective it may be for arresting the frequency event. This paper proposes a predictive PV inverter control method for very fast and accurate control of active power. This rapid active power control method will increase the effectiveness of various higher-level controls designed to mitigate grid frequency contingency events,more » including fast power-frequency droop, inertia emulation, and fast frequency response, without the need for energy storage. The rapid active power control method, coupled with a maximum power point estimation method, is implemented in a prototype PV inverter connected to a PV array. The prototype inverter's response to various frequency events is experimentally confirmed to be fast (beginning within 2 line cycles and completing within 4.5 line cycles of a severe test event) and accurate (below 2% steady-state error).« less

High Power High Efficiency Diode Laser Stack for Processing

NASA Astrophysics Data System (ADS)

Gu, Yuanyuan; Lu, Hui; Fu, Yueming; Cui, Yan

2018-03-01

High-power diode lasers based on GaAs semiconductor bars are well established as reliable and highly efficient laser sources. As diode laser is simple in structure, small size, longer life expectancy with the advantages of low prices, it is widely used in the industry processing, such as heat treating, welding, hardening, cladding and so on. Respectively, diode laser could make it possible to establish the practical application because of rectangular beam patterns which are suitable to make fine bead with less power. At this power level, it can have many important applications, such as surgery, welding of polymers, soldering, coatings and surface treatment of metals. But there are some applications, which require much higher power and brightness, e.g. hardening, key hole welding, cutting and metal welding. In addition, High power diode lasers in the military field also have important applications. So all developed countries have attached great importance to high-power diode laser system and its applications. This is mainly due their low performance. In this paper we will introduce the structure and the principle of the high power diode stack.

Three Days of Intermittent Fasting: Repeated-Sprint Performance Decreased by Vertical-Stiffness Impairment.

PubMed

Cherif, Anissa; Meeusen, Romain; Farooq, Abdulaziz; Ryu, Joong; Fenneni, Mohamed Amine; Nikolovski, Zoran; Elshafie, Sittana; Chamari, Karim; Roelands, Bart

2017-03-01

To examine the effects of 3 d of intermittent fasting (3d-IF: abstaining from eating/drinking from dawn to sunset) on physical performance and metabolic responses to repeated sprints (RSs). Twenty-one active males performed an RS test (2 sets: 5 × 5-s maximal sprints with 25 s of recovery between and 3 min of recovery between sets on an instrumented treadmill) in 2 conditions: counterbalanced fed/control session (CS) and fasting session (FS). Biomechanical and biochemical markers were assessed preexercise and postexercise. Significant main effects of IF were observed for sprints: maximal speed (P = .016), mean speed (P = .015), maximal power (P = .035), mean power (P = .049), vertical stiffness (P = .032), and vertical center-of-mass displacement (P = .047). Sprint speed and vertical stiffness decreased during the 1st (P = .003 and P = .005) and 2nd sprints (P = .046 and P = .048) of set 2, respectively. Postexercise insulin decreased in CS (P = .023) but not in FS (P = .230). Free-fatty-acid levels were higher in FS than in CS at preexercise (P < .001) and at postexercise (P = .009). High-density lipoprotein cholesterol (HDL-C) was higher at postexercise in FS (1.32 ± 0.22 mmol/L) than in CS (1.26 ± 0.21 mmol/L, P = .039). The triglyceride (TG) concentration was decreased in FS (P < .05) compared with CS. 3d-IF impaired speed and power through a decrease in vertical stiffness during the initial runs of the 2nd set of RS. The findings of the current study confirmed the benefits of 3d-IF: improved HDL-C and TG profiles while maintaining total cholesterol and low-density lipoprotein cholesterol levels. Moreover, improving muscle power might be a key factor to retain a higher vertical stiffness and to partly counteract the negative effects of intermittent fasting.

Standby battery requirements for telecommunications power

NASA Astrophysics Data System (ADS)

May, G. J.

The requirements for standby power for telecommunications are changing as the network moves from conventional systems to Internet Protocol (IP) telephony. These new systems require higher power levels closer to the user but the level of availability and reliability cannot be compromised if the network is to provide service in the event of a failure of the public utility. Many parts of these new networks are ac rather than dc powered with UPS systems for back-up power. These generally have lower levels of reliability than dc systems and the network needs to be designed such that overall reliability is not reduced through appropriate levels of redundancy. Mobile networks have different power requirements. Where there is a high density of nodes, continuity of service can be reasonably assured with short autonomy times. Furthermore, there is generally no requirement that these networks are the provider of last resort and therefore, specifications for continuity of power are directed towards revenue protection and overall reliability targets. As a result of these changes, battery requirements for reserve power are evolving. Shorter autonomy times are specified for parts of the network although a large part will continue to need support for hours rather minutes. Operational temperatures are increasing and battery solutions that provide longer life in extreme conditions are becoming important. Different battery technologies will be discussed in the context of these requirements. Conventional large flooded lead/acid cells both with pasted and tubular plates are used in larger central office applications but the majority of requirements are met with valve-regulated lead/acid (VRLA) batteries. The different types of VRLA battery will be described and their suitability for various applications outlined. New developments in battery construction and battery materials have improved both performance and reliability in recent years. Alternative technologies are also being proposed for telecommunications power, either different battery chemistries including lithium batteries, flywheel energy storage or the use of fuel cells. These will be evaluated and the position of lead/acid batteries in the medium term for this important market will be assessed.

Power-constrained supercomputing

NASA Astrophysics Data System (ADS)

Bailey, Peter E.

As we approach exascale systems, power is turning from an optimization goal to a critical operating constraint. With power bounds imposed by both stakeholders and the limitations of existing infrastructure, achieving practical exascale computing will therefore rely on optimizing performance subject to a power constraint. However, this requirement should not add to the burden of application developers; optimizing the runtime environment given restricted power will primarily be the job of high-performance system software. In this dissertation, we explore this area and develop new techniques that extract maximum performance subject to a particular power constraint. These techniques include a method to find theoretical optimal performance, a runtime system that shifts power in real time to improve performance, and a node-level prediction model for selecting power-efficient operating points. We use a linear programming (LP) formulation to optimize application schedules under various power constraints, where a schedule consists of a DVFS state and number of OpenMP threads for each section of computation between consecutive message passing events. We also provide a more flexible mixed integer-linear (ILP) formulation and show that the resulting schedules closely match schedules from the LP formulation. Across four applications, we use our LP-derived upper bounds to show that current approaches trail optimal, power-constrained performance by up to 41%. This demonstrates limitations of current systems, and our LP formulation provides future optimization approaches with a quantitative optimization target. We also introduce Conductor, a run-time system that intelligently distributes available power to nodes and cores to improve performance. The key techniques used are configuration space exploration and adaptive power balancing. Configuration exploration dynamically selects the optimal thread concurrency level and DVFS state subject to a hardware-enforced power bound. Adaptive power balancing efficiently predicts where critical paths are likely to occur and distributes power to those paths. Greater power, in turn, allows increased thread concurrency levels, CPU frequency/voltage, or both. We describe these techniques in detail and show that, compared to the state-of-the-art technique of using statically predetermined, per-node power caps, Conductor leads to a best-case performance improvement of up to 30%, and an average improvement of 19.1%. At the node level, an accurate power/performance model will aid in selecting the right configuration from a large set of available configurations. We present a novel approach to generate such a model offline using kernel clustering and multivariate linear regression. Our model requires only two iterations to select a configuration, which provides a significant advantage over exhaustive search-based strategies. We apply our model to predict power and performance for different applications using arbitrary configurations, and show that our model, when used with hardware frequency-limiting in a runtime system, selects configurations with significantly higher performance at a given power limit than those chosen by frequency-limiting alone. When applied to a set of 36 computational kernels from a range of applications, our model accurately predicts power and performance; our runtime system based on the model maintains 91% of optimal performance while meeting power constraints 88% of the time. When the runtime system violates a power constraint, it exceeds the constraint by only 6% in the average case, while simultaneously achieving 54% more performance than an oracle. Through the combination of the above contributions, we hope to provide guidance and inspiration to research practitioners working on runtime systems for power-constrained environments. We also hope this dissertation will draw attention to the need for software and runtime-controlled power management under power constraints at various levels, from the processor level to the cluster level.

Next-generation fiber lasers enabled by high-performance components

NASA Astrophysics Data System (ADS)

Kliner, D. A. V.; Victor, B.; Rivera, C.; Fanning, G.; Balsley, D.; Farrow, R. L.; Kennedy, K.; Hampton, S.; Hawke, R.; Soukup, E.; Reynolds, M.; Hodges, A.; Emery, J.; Brown, A.; Almonte, K.; Nelson, M.; Foley, B.; Dawson, D.; Hemenway, D. M.; Urbanek, W.; DeVito, M.; Bao, L.; Koponen, J.; Gross, K.

2018-02-01

Next-generation industrial fiber lasers enable challenging applications that cannot be addressed with legacy fiber lasers. Key features of next-generation fiber lasers include robust back-reflection protection, high power stability, wide power tunability, high-speed modulation and waveform generation, and facile field serviceability. These capabilities are enabled by high-performance components, particularly pump diodes and optical fibers, and by advanced fiber laser designs. We summarize the performance and reliability of nLIGHT diodes, fibers, and next-generation industrial fiber lasers at power levels of 500 W - 8 kW. We show back-reflection studies with up to 1 kW of back-reflected power, power-stability measurements in cw and modulated operation exhibiting sub-1% stability over a 5 - 100% power range, and high-speed modulation (100 kHz) and waveform generation with a bandwidth 20x higher than standard fiber lasers. We show results from representative applications, including cutting and welding of highly reflective metals (Cu and Al) for production of Li-ion battery modules and processing of carbon fiber reinforced polymers.

Photon noise from chaotic and coherent millimeter-wave sources measured with horn-coupled, aluminum lumped-element kinetic inductance detectors

NASA Astrophysics Data System (ADS)

Flanigan, D.; McCarrick, H.; Jones, G.; Johnson, B. R.; Abitbol, M. H.; Ade, P.; Araujo, D.; Bradford, K.; Cantor, R.; Che, G.; Day, P.; Doyle, S.; Kjellstrand, C. B.; Leduc, H.; Limon, M.; Luu, V.; Mauskopf, P.; Miller, A.; Mroczkowski, T.; Tucker, C.; Zmuidzinas, J.

2016-02-01

We report photon-noise limited performance of horn-coupled, aluminum lumped-element kinetic inductance detectors at millimeter wavelengths. The detectors are illuminated by a millimeter-wave source that uses an active multiplier chain to produce radiation between 140 and 160 GHz. We feed the multiplier with either amplified broadband noise or a continuous-wave tone from a microwave signal generator. We demonstrate that the detector response over a 40 dB range of source power is well-described by a simple model that considers the number of quasiparticles. The detector noise-equivalent power (NEP) is dominated by photon noise when the absorbed power is greater than approximately 1 pW, which corresponds to NEP≈2 ×10-17 W Hz-1 /2 , referenced to absorbed power. At higher source power levels, we observe the relationships between noise and power expected from the photon statistics of the source signal: NEP∝P for broadband (chaotic) illumination and NEP∝P1 /2 for continuous-wave (coherent) illumination.

Sonocrystallization of Interesterified Soybean Oil: Effect of Saturation Level and Supercooling.

PubMed

Lee, Juhee; Claro da Silva, Roberta; Gibon, Veronique; Martini, Silvana

2018-04-01

The aim of this study was to investigate the effects of supercooling and degree of saturation on lipid sonocrystallization under similar driving force of crystallization. Samples consisting of 100%, 50%, and 20% interesterified soybean oil (IESBO) diluted in high-oleic sunflower oil (HOSFO) were crystallized with and without high-intensity ultrasound (HIU). Two power levels were used by changing the amplitude of vibration of the tip (24 μm and 108 μm of tip amplitude). HIU operating at a frequency of 20 kHz was applied for 10 s. Sonication induced crystallization in the 100% IESBO sample and sonication power did not affect the results. A greater induction in crystallization was observed when higher power levels were used in the 50% IESBO sample, while no effect was observed in the crystallization kinetics of the 20% IESBO samples. Changes in the crystallization kinetics affected physical properties of the material, influencing elasticity. For example, sonication increased the elasticity of the 100% IESBO sample for both tip amplitudes from 435.9 ± 173.3 Pa to 72735.0 ± 9547.9 Pa for the nonsonicated and sonicated samples using 108 μm of amplitude, respectively. However, sonication only increased the elasticity in the 50% sample when used at the higher power level of 108 μm from 564.2 ± 175.2 Pa to 21774.0 ± 5694.9 Pa, and it did not affect the elasticity of the 20% IESBO samples. These results show that the level of saturation and the degree of supercooling affect sonication efficiency. High-intensity ultrasound (HIU) has been used as a novel method for changing the crystallization behavior of fats. HIU can be used to improve the physical properties of trans-free fats that are low in saturated fatty acids. Although recent studies have proven the effectiveness of this method to induce crystallization, the process must still be optimized to the industrial setting. All process parameters should be considered during the application of HIU, as they directly affect the final product. The aim of this paper was to investigate the effects of HIU and process conditions such as tip amplitude, degree of supercooling, and saturation level on the crystallization behavior of commercial interesterified soybean oil. © 2018 Institute of Food Technologists®.

Photo-assisted intersystem crossing: The predominant triplet formation mechanism in some isolated polycyclic aromatic molecules excited with pulsed lasers

DOE PAGES

Johnson, Philip M.; Sears, Trevor J.

2015-07-28

Naphthalene, anthracene, and phenanthrene are shown to have very long-lived triplet lifetimes when the isolated molecules are excited with nanosecond pulsed lasers resonant with the lowest singlet state. For naphthalene, triplet state populations are created only during the laser pulse, excluding the possibility of normal intersystem crossing at the one photon level, and all molecules have triplet lifetimes greater than hundreds of microseconds, similar to the behavior previously reported for phenylacetylene. Although containing 7–12 thousand cm⁻¹ of vibrational energy, the triplet molecules have ionization thresholds appropriate to vibrationless T₁ states. The laser power dependences (slopes of log-log power plots) ofmore » the excited singlet and triplet populations are about 0.7 for naphthalene and about 0.5 for anthracene. Kinetic modeling of the power dependences successfully reproduces the experimental results and suggests that the triplet formation mechanism involves an enhanced spin orbit coupling caused by sigma character in states at the 2-photon level. Symmetry Adapted Cluster-Configuration Interaction calculations produced excited state absorption spectra to provide guidance for estimating kinetic rates and the sigma character present in higher electronic states. It is concluded that higher excited state populations are significant when larger molecules are excited with pulsed lasers and need to be taken into account whenever discussing the molecular photodynamics.« less

Relativistic high-current electron-beam stopping-power characterization in solids and plasmas: collisional versus resistive effects.

PubMed

Vauzour, B; Santos, J J; Debayle, A; Hulin, S; Schlenvoigt, H-P; Vaisseau, X; Batani, D; Baton, S D; Honrubia, J J; Nicolaï, Ph; Beg, F N; Benocci, R; Chawla, S; Coury, M; Dorchies, F; Fourment, C; d'Humières, E; Jarrot, L C; McKenna, P; Rhee, Y J; Tikhonchuk, V T; Volpe, L; Yahia, V

2012-12-21

We present experimental and numerical results on intense-laser-pulse-produced fast electron beams transport through aluminum samples, either solid or compressed and heated by laser-induced planar shock propagation. Thanks to absolute K(α) yield measurements and its very good agreement with results from numerical simulations, we quantify the collisional and resistive fast electron stopping powers: for electron current densities of ≈ 8 × 10(10) A/cm(2) they reach 1.5 keV/μm and 0.8 keV/μm, respectively. For higher current densities up to 10(12)A/cm(2), numerical simulations show resistive and collisional energy losses at comparable levels. Analytical estimations predict the resistive stopping power will be kept on the level of 1 keV/μm for electron current densities of 10(14)A/cm(2), representative of the full-scale conditions in the fast ignition of inertially confined fusion targets.

Laboratory versus outdoor cycling conditions: differences in pedaling biomechanics.

PubMed

Bertucci, William; Grappe, Frederic; Groslambert, Alain

2007-05-01

The aim of our study was to compare crank torque profile and perceived exertion between the Monark ergometer (818 E) and two outdoor cycling conditions: level ground and uphill road cycling. Seven male cyclists performed seven tests in seated position at different pedaling cadences: (a) in the laboratory at 60, 80, and 100 rpm; (b) on level terrain at 80 and 100 rpm; and (c) on uphill terrain (9.25% grade) at 60 and 80 rpm. The cyclists exercised for 1 min at their maximal aerobic power. The Monark ergometer and the bicycle were equipped with the SRM Training System (Schoberer, Germany) for the measurement of power output (W), torque (Nxm), pedaling cadence (rpm), and cycling velocity (kmxh-1). The most important findings of this study indicate that at maximal aerobic power the crank torque profiles in the Monark ergometer (818 E) were significantly different (especially on dead points of the crank cycle) and generate a higher perceived exertion compared with road cycling conditions.

Intestinal Fatty Acid Binding Protein as a Marker of Necrosis and Severity in Acute Pancreatitis.

PubMed

Kupčinskas, Juozas; Gedgaudas, Rolandas; Hartman, Hannes; Sippola, Tomi; Lindström, Outi; Johnson, Colin D; Regnér, Sara

2018-07-01

The aim of this study was to study intestinal fatty acid binding protein (i-FABP) as a potential biomarker in predicting severity of acute pancreatitis (AP). In a prospective multicenter cohort study, plasma levels of i-FABP were measured in 402 patients with AP. Severity of AP was determined based on the 1992 Atlanta Classification. Admission levels of plasma i-FABP were significantly higher in patients with pancreatic necrosis, in patients having systemic complications, in patients treated invasively, in patients treated in the intensive care unit, in patients with severe AP, and in deceased patients. Plasma i-FABP levels on admission yielded an area under curve (AUC) of 0.732 in discriminating patients with or without pancreatic necrosis and AUC of 0.669 in predicting severe AP. Combination of levels of i-FABP and venous lactate on the day of admission showed higher discriminative power in severe AP-AUC of 0.808. Higher i-FABP levels on admission were associated with pancreatic necrosis, systemic complications, and severe AP. Low levels of i-FABP had a high negative predictive value for pancreatic necrosis and severe AP. Combination of levels of i-FABP and venous lactates on admission were superior to either of markers used alone in predicting severe AP.

Effect of training and level of external auditory feedback on the singing voice: volume and quality

PubMed Central

Bottalico, Pasquale; Graetzer, Simone; Hunter, Eric J.

2015-01-01

Background Previous research suggests that classically trained professional singers rely not only on external auditory feedback but also on proprioceptive feedback associated with internal voice sensitivities. Objectives The Lombard Effect in singers and the relationship between Sound Pressure Level (SPL) and external auditory feedback was evaluated for professional and non-professional singers. Additionally, the relationship between voice quality, evaluated in terms of Singing Power Ratio (SPR), and external auditory feedback, level of accompaniment, voice register and singer gender was analyzed. Methods The subjects were 10 amateur or beginner singers, and 10 classically-trained professional or semi-professional singers (10 males and 10 females). Subjects sang an excerpt from the Star-spangled Banner with three different levels of the accompaniment, 70, 80 and 90 dBA, and with three different levels of external auditory feedback. SPL and the SPR were analyzed. Results The Lombard Effect was stronger for non-professional singers than professional singers. Higher levels of external auditory feedback were associated with a reduction in SPL. As predicted, the mean SPR was higher for professional than non-professional singers. Better voice quality was detected in the presence of higher levels of external auditory feedback. Conclusions With an increase in training, the singer’s reliance on external auditory feedback decreases. PMID:26186810

Effect of Training and Level of External Auditory Feedback on the Singing Voice: Volume and Quality.

PubMed

Bottalico, Pasquale; Graetzer, Simone; Hunter, Eric J

2016-07-01

Previous research suggests that classically trained professional singers rely not only on external auditory feedback but also on proprioceptive feedback associated with internal voice sensitivities. The Lombard effect and the relationship between sound pressure level (SPL) and external auditory feedback were evaluated for professional and nonprofessional singers. Additionally, the relationship between voice quality, evaluated in terms of singing power ratio (SPR), and external auditory feedback, level of accompaniment, voice register, and singer gender was analyzed. The subjects were 10 amateur or beginner singers and 10 classically trained professional or semiprofessional singers (10 men and 10 women). Subjects sang an excerpt from the Star-Spangled Banner with three different levels of the accompaniment, 70, 80, and 90 dBA and with three different levels of external auditory feedback. SPL and SPR were analyzed. The Lombard effect was stronger for nonprofessional singers than professional singers. Higher levels of external auditory feedback were associated with a reduction in SPL. As predicted, the mean SPR was higher for professional singers than nonprofessional singers. Better voice quality was detected in the presence of higher levels of external auditory feedback. With an increase in training, the singer's reliance on external auditory feedback decreases. Copyright © 2016 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

Aquatic balance in Vegoritis Lake, West Macedonia, Greece, relating to lignite mining works in the area

NASA Astrophysics Data System (ADS)

Dimitrakopoulos, D.; Grigorakou, E.; Koumantakis, J.

2003-04-01

Vegoritis Lake, which is located at Vegoritis closed Basin in West Macedonia, Greece, is the biggest lake in Greece. In 1994 the area of the lake was 35 Km2 with maximum depth 42 m at the northwestern part of the lake. It is the final receiving body of the surface runoff of the hydrological basin. Moreover, it is the surficial appearance of an enormous and not well-known karstic aquifer. Being a closed hydrological basin any interference in surface or groundwater conditions in every part of its area affects the level of the lake. The level of the lake in 1900 was 525 masl, in 1942 was 542 masl reaching the higher level of 543 masl in 1956. The increase of the level of the lake was due to the drainage of Ptolemais (Sarigiol) swamp through Soulou drain ditches that transfer the water in the lake. Since then, a continuous drawdown took place with small periods of rising of water level. Today, the level of the lake is declined in a smaller rate having reached the level of 510 masl. Water coming from the lake has been used in the past, and in some cases still does, for agricultural, industrial and domestic use, for hydropower generation and for the cooling system of power plants. Moreover, P.P.C. (Public Power Corporation of Greece) develops an intense activity in the area with the exploitation of the lignite deposits of the basin and power generation in several Power Plants. Few years ago significant quantities from Vegoritis Lake were used for hydro power of Agras Power Plant. With the elaboration of the existent data (water level measurements, recharge, discharge) the connection between the lowering of the surface of the lake and the subtracted quantities through the Arnissa Tunel the first years of its use, is obvious. The last twenty years the condition has change. Outflow through the Arnissa Tunnel for hydropower has stopped. The continued lowering of the level of the lake is caused, mainly, by overexploitation due to the intense increase of the irrigating land. The dewatering of the aquifers for the protection of the lignite mine seems to have an insignificant influence on the aquatic balance, as the water is discharged again into the streams and rivers of the closed basin.

Prediction of the far field noise from wind energy farms

NASA Technical Reports Server (NTRS)

Shepherd, K. P.; Hubbard, H. H.

1986-01-01

The basic physical factors involved in making predictions of wind turbine noise and an approach which allows for differences in the machines, the wind energy farm configurations and propagation conditions are reviewed. Example calculations to illustrate the sensitivity of the radiated noise to such variables as machine size, spacing and numbers, and such atmosphere variables as absorption and wind direction are presented. It is found that calculated far field distances to particular sound level contours are greater for lower values of atmospheric absorption, for a larger total number of machines, for additional rows of machines and for more powerful machines. At short and intermediate distances, higher sound pressure levels are calculated for closer machine spacings, for more powerful machines, for longer row lengths and for closer row spacings.

Flow structure in continuous flow electrophoresis chambers

NASA Technical Reports Server (NTRS)

Deiber, J. A.; Saville, D. A.

1982-01-01

There are at least two ways that hydrodynamic processes can limit continiuous flow electrophoresis. One arises from the sensitivity of the flow to small temerature gradients, especially at low flow rates and power levels. This sensitivity can be suppressed, at least in principle, by providing a carefully tailored, stabilizing temperature gradient in the cooling system that surrounds the flow channel. At higher power levels another limitation arises due to a restructuring of the main flow. This restructuring is caused by buoyancy, which is in turn affected by the electro-osmotic crossflow. Approximate solutions to appropriate partial differential equations have been computed by finite difference methods. One set of results is described here to illustrate the strong coupling between the structure of the main (axial) flow and the electro-osmotic flow.

Early Oscillation Detection Technique for Hybrid DC/DC Converters

NASA Technical Reports Server (NTRS)

Wang, Bright L.

2011-01-01

Oscillation or instability is a situation that must be avoided for reliable hybrid DC/DC converters. A real-time electronics measurement technique was developed to detect catastrophic oscillations at early stages for hybrid DC/DC converters. It is capable of identifying low-level oscillation and determining the degree of the oscillation at a unique frequency for every individual model of the converters without disturbing their normal operations. This technique is specially developed for space-used hybrid DC/DC converters, but it is also suitable for most of commercial and military switching-mode power supplies. This is a weak-electronic-signal detection technique to detect hybrid DC/DC converter oscillation presented as a specific noise signal at power input pins. It is based on principles of feedback control loop oscillation and RF signal modulations, and is realized by using signal power spectral analysis. On the power spectrum, a channel power amplitude at characteristic frequency (CPcf) and a channel power amplitude at switching frequency (CPsw) are chosen as oscillation level indicators. If the converter is stable, the CPcf is a very small pulse and the CPsw is a larger, clear, single pulse. At early stage of oscillation, the CPcf increases to a certain level and the CPsw shows a small pair of sideband pulses around it. If the converter oscillates, the CPcf reaches to a higher level and the CPsw shows more high-level sideband pulses. A comprehensive stability index (CSI) is adopted as a quantitative measure to accurately assign a degree of stability to a specific DC/DC converter. The CSI is a ratio of normal and abnormal power spectral density, and can be calculated using specified and measured CPcf and CPsw data. The novel and unique feature of this technique is the use of power channel amplitudes at characteristic frequency and switching frequency to evaluate stability and identify oscillations at an early stage without interfering with a DC/DC converter s normal operation. This technique eliminates the probing problem of a gain/phase margin method by connecting the power input to a spectral analyzer. Therefore, it is able to evaluate stability for all kinds of hybrid DC/DC converters with or without remote sense pins, and is suitable for real-time and in-circuit testing. This frequency-domain technique is more sensitive to detect oscillation at early stage than the time-domain method using an oscilloscope.

Launch vehicle and power level impacts on electric GEO insertion

NASA Technical Reports Server (NTRS)

Oleson, Steven R.; Myers, Roger M.

1996-01-01

Solar Electric Propulsion (SEP) has been shown to increase net geosynchronous spacecraft mass when used for station keeping and final orbit insertion. The impact of launch vehicle selection and power level on the benefits of this approach were examined for 20 and 25 kW systems launched using the Ariane 5, Atlas IIAR, Long March, Proton, and Sea Launch vehicles. Two advanced on-board propulsion technologies, 5 kW ion and Hall thruster systems, were used to establish the relative merits of the technologies and launch vehicles. GaAs solar arrays were assumed. The analysis identifies the optimal starting orbits for the SEP orbit raising/plane changing while considering the impacts of radiation degradation in the Van Allen belts, shading, power degradation, and oblateness. This use of SEP to provide part of the orbit insertion results in net mass increases of 15 - 38% and 18 - 46% for one to two month trip times, respectively, over just using SEP for 15 years of north/south station keeping. SEP technology was shown to have a greater impact on net masses of launch vehicles with higher launch latitudes when avoidance of solar array and payload degradation is desired. This greater impact of SEP could help reduce the plane changing disadvantage of high latitude launch sites. Comparison with results for 10 and 15 kW systems show clear benefits of incremental increases in SEP power level, suggesting that an evolutionary approach to high power SEP for geosynchronous spacecraft is possible.

Preliminary Results of Performance Measurements on a Cylindrical Hall-Effect Thruster with Magnetic Field Generated by Permanent Magnets

NASA Technical Reports Server (NTRS)

Polzin, K. A.; Raitses, Y.; Merino, E.; Fisch, N. J.

2008-01-01

The performance of a low-power cylindrical Hall thruster, which more readily lends itself to miniaturization and low-power operation than a conventional (annular) Hall thruster, was measured using a planar plasma probe and a thrust stand. The field in the cylindrical thruster was produced using permanent magnets, promising a power reduction over previous cylindrical thruster iterations that employed electromagnets to generate the required magnetic field topology. Two sets of ring-shaped permanent magnets are used, and two different field configurations can be produced by reorienting the poles of one magnet relative to the other. A plasma probe measuring ion flux in the plume is used to estimate the current utilization for the two magnetic configurations. The measurements indicate that electron transport is impeded much more effectively in one configuration, implying a higher thrust efficiency. Preliminary thruster performance measurements on this configuration were obtained over a power range of 100-250 W. The thrust levels over this power range were 3.5-6.5 mN, with anode efficiencies and specific impulses spanning 14-19% and 875- 1425 s, respectively. The magnetic field in the thruster was lower for the thrust measurements than the plasma probe measurements due to heating and weakening of the permanent magnets, reducing the maximum field strength from 2 kG to roughly 750-800 G. The discharge current levels observed during thrust stand testing were anomalously high compared to those levels measured in previous experiments with this thruster.

Laser absorption phenomena in flowing gas devices

NASA Technical Reports Server (NTRS)

Chapman, P. K.; Otis, J. H.

1976-01-01

A theoretical and experimental investigation is presented of inverse Bremsstrahlung absorption of CW CO2 laser radiation in flowing gases seeded with alkali metals. In order to motivate this development, some simple models are described of several space missions which could use laser powered rocket vehicles. Design considerations are given for a test call to be used with a welding laser, using a diamond window for admission of laser radiation at power levels in excess of 10 kW. A detailed analysis of absorption conditions in the test cell is included. The experimental apparatus and test setup are described and the results of experiments presented. Injection of alkali seedant and steady state absorption of the laser radiation were successfully demonstrated, but problems with the durability of the diamond windows at higher powers prevented operation of the test cell as an effective laser powered thruster.

All-solid-state continuous-wave frequency doubling Nd:LuVO4/LBO laser with 2.17 W output power at 543 nm

NASA Astrophysics Data System (ADS)

Li, B.; Zhao, L.; Zhang, Y. B.; Zheng, Q.; Zhao, Y.; Yao, Y.

2013-03-01

Efficient and compact green-yellow laser output at 543 nm is generated by intracavity frequency doubling of a CW diode-pumped Nd:LuVO4 laser at 1086 nm under the condition of suppressing the higher gain transition near 1064 nm. With 16 W of diode pump power and the frequency-doubling crystal LBO, as high as 2.17 W of CW output power at 543 nm is achieved, corresponding to an optical-to-optical conversion efficiency of 13.6% and the output power stability over 8 hours is better than 2.86%. To the best of our knowledge, this is the highest watt-level laser at 543 nm generated by intracavity frequency doubling of a diode pumped Nd:LuVO4 laser at 1086 nm.

Design of New Power Management Circuit for Light Energy Harvesting System

PubMed Central

Jafer, Issa; Stack, Paul; MacNamee, Kevin

2016-01-01

Nowadays, it can be observed that Wireless Sensors Networks (WSN) are taking increasingly vital roles in many applications, such as building energy monitoring and control, which is the focus of the work in this paper. However, the main challenging issue with adopting WSN technology is the use of power sources such as batteries, which have a limited lifetime. A smart solution that could tackle this problem is using Energy Harvesting technology. The work in this paper will be focused on proposing a new power management design through harvesting indoor light intensity. The new approach is inspired by the use of the Fractional Open Circuit Voltage based Maximum Power Point tracking (MPPT) concept for sub mw Photo Voltaic (PV) cells. The new design adopts two main features: First, it minimizes the power consumed by the power management section; and second, it maximizes the MPPT-converted output voltage and consequently improves the efficiency of the power conversion in the sub mw power level. The new experimentally-tested design showed an improvement of 81% in the efficiency of MPPT conversion using 0.5 mW input power in comparison with the other presented solutions that showed less efficiency with higher input power. PMID:26907300

Design and experiment of a directional coupler for X-band long pulse high power microwaves.

PubMed

Bai, Zhen; Li, Guolin; Zhang, Jun; Jin, Zhenxing

2013-03-01

Higher power and longer pulse are the trend of the development of high power microwave (HPM), and then some problems emerge in measuring the power of HPM because rf breakdown is easier to occur under the circumstance of high power (the level of gigawatt) and long pulse (about 100 ns). In order to measure the power of the dominant TM₀₁ mode of an X-band long pulse overmoded HPM source, a directional coupler with stable coupling coefficient, high directivity, and high power handling capacity in wide band is investigated numerically and experimentally. At the central frequency 9.4 GHz, the simulation results show that the coupling coefficient is -59.6 dB with the directivity of 35 dB and the power handling capacity of 2 GW. The coupling coefficient is calibrated to be accordant with the simulation results. The high power tests are performed on an X-band long pulse HPM source, whose output mode is mainly TM₀₁ mode, and the results show that the measured power and waveform of the directional coupler have a good consistency with the far-field measuring results.

More Efficient Power Conversion for EVs: Gallium-Nitride Advanced Power Semiconductor and Packaging

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

None

2010-02-01

Broad Funding Opportunity Announcement Project: Delphi is developing power converters that are smaller and more energy efficient, reliable, and cost-effective than current power converters. Power converters rely on power transistors which act like a very precisely controlled on-off switch, controlling the electrical energy flowing through an electrical circuit. Most power transistors today use silicon (Si) semiconductors. However, Delphi is using semiconductors made with a thin layer of gallium-nitride (GaN) applied on top of the more conventional Si material. The GaN layer increases the energy efficiency of the power transistor and also enables the transistor to operate at much higher temperatures,more » voltages, and power-density levels compared to its Si counterpart. Delphi is packaging these high-performance GaN semiconductors with advanced electrical connections and a cooling system that extracts waste heat from both sides of the device to further increase the device’s efficiency and allow more electrical current to flow through it. When combined with other electronic components on a circuit board, Delphi’s GaN power transistor package will help improve the overall performance and cost-effectiveness of HEVs and EVs.« less

High-power and steady-state operation of ICRF heating in the large helical device

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

Mutoh, T., E-mail: mutoh@nifs.ac.jp; Seki, T.; Saito, K.

2015-12-10

Recent progress in an ion cyclotron range of frequencies (ICRF) heating system and experiment results in a Large Helical Device (LHD) are reported. Three kinds of ICRF antenna pairs were installed in the LHD, and the operation power regimes were extended up to 4.5 MW; also, the steady-state operation was extended for more than 45 min in LHD at a MW power level. We studied ICRF heating physics in heliotron configuration using a Hand Shake type (HAS) antenna, Field Aligned Impedance Transforming (FAIT) antenna, and Poloidal Array (PA) antenna, and established the optimum minority-ion heating scenario in an LHD. The FAITmore » antenna having a novel impedance transformer inside the vacuum chamber could reduce the VSWR and successfully injected a higher power to plasma. We tested the PA antennas completely removing the Faraday-shield pipes to avoid breakdown and to increase the plasma coupling. The heating performance was almost the same as other antennas; however, the heating efficiency was degraded when the gap between the antenna and plasma surface was large. Using these three kinds of antennas, ICRF heating could contribute to raising the plasma beta with the second- and third-harmonic cyclotron heating mode, and also to raising the ion temperature as discharge cleaning tools. In 2014, steady-state operation plasma with a line-averaged electron density of 1.2 × 10{sup 19} m{sup −3}, ion and electron temperature of 2 keV, and plasma sustainment time of 48 min was achieved with ICH and ECH heating power of 1.2 MW for majority helium with minority hydrogen. In 2015, the higher-power steady-state operation with a heating power of up to 3 MW was tested with higher density of 3 × 10{sup 19} m{sup −3}.« less

Modeling the Ocean Tide for Tidal Power Generation Applications

NASA Astrophysics Data System (ADS)

Kawase, M.; Gedney, M.

2014-12-01

Recent years have seen renewed interest in the ocean tide as a source of energy for electrical power generation. Unlike in the 1960s, when the tidal barrage was the predominant method of power extraction considered and implemented, the current methodology favors operation of a free-stream turbine or an array of them in strong tidal currents. As tidal power generation moves from pilot-scale projects to actual array implementations, numerical modeling of tidal currents is expected to play an increasing role in site selection, resource assessment, array design, and environmental impact assessment. In this presentation, a simple, coupled ocean/estuary model designed for research into fundamental aspects of tidal power generation is described. The model consists of a Pacific Ocean-size rectangular basin and a connected fjord-like embayment with dimensions similar to that of Puget Sound, Washington, one of the potential power generation sites in the United States. The model is forced by an idealized lunar tide-generating potential. The study focuses on the energetics of a tidal system including tidal power extraction at both global and regional scales. The hyperbolic nature of the governing shallow water equations means consequence of tidal power extraction cannot be limited to the local waters, but is global in extent. Modeling power extraction with a regional model with standard boundary conditions introduces uncertainties of 3 ~ 25% in the power extraction estimate depending on the level of extraction. Power extraction in the model has a well-defined maximum (~800 MW in a standard case) that is in agreement with previous theoretical studies. Natural energy dissipation and tidal power extraction strongly interact; for a turbine array of a given capacity, the higher the level of natural dissipation the lower the power the array can extract. Conversely, power extraction leads to a decrease in the level of natural dissipation (Figure) as well as the tidal range and the current speed. In the standard case considered, at the maximum power extraction the tidal range in the estuary is reduced by 37% and the natural dissipation by 78% from the unperturbed state. Thus, environmental consequences of power generation are likely to become the limiting factor on the scale of resource development before the physical maximum is reached.

Image Feature Types and Their Predictions of Aesthetic Preference and Naturalness

PubMed Central

Ibarra, Frank F.; Kardan, Omid; Hunter, MaryCarol R.; Kotabe, Hiroki P.; Meyer, Francisco A. C.; Berman, Marc G.

2017-01-01

Previous research has investigated ways to quantify visual information of a scene in terms of a visual processing hierarchy, i.e., making sense of visual environment by segmentation and integration of elementary sensory input. Guided by this research, studies have developed categories for low-level visual features (e.g., edges, colors), high-level visual features (scene-level entities that convey semantic information such as objects), and how models of those features predict aesthetic preference and naturalness. For example, in Kardan et al. (2015a), 52 participants provided aesthetic preference and naturalness ratings, which are used in the current study, for 307 images of mixed natural and urban content. Kardan et al. (2015a) then developed a model using low-level features to predict aesthetic preference and naturalness and could do so with high accuracy. What has yet to be explored is the ability of higher-level visual features (e.g., horizon line position relative to viewer, geometry of building distribution relative to visual access) to predict aesthetic preference and naturalness of scenes, and whether higher-level features mediate some of the association between the low-level features and aesthetic preference or naturalness. In this study we investigated these relationships and found that low- and high- level features explain 68.4% of the variance in aesthetic preference ratings and 88.7% of the variance in naturalness ratings. Additionally, several high-level features mediated the relationship between the low-level visual features and aaesthetic preference. In a multiple mediation analysis, the high-level feature mediators accounted for over 50% of the variance in predicting aesthetic preference. These results show that high-level visual features play a prominent role predicting aesthetic preference, but do not completely eliminate the predictive power of the low-level visual features. These strong predictors provide powerful insights for future research relating to landscape and urban design with the aim of maximizing subjective well-being, which could lead to improved health outcomes on a larger scale. PMID:28503158

Mediating influences of social support on stress at Three Mile Island.

PubMed

Fleming, R; Baum, A; Gisriel, M M; Gatchel, R J

1982-09-01

Symptom reporting, task performance, and urinary catecholamine excretion were studied in a group of people living near the Three Mile Island nuclear power plant and in control populations. More than a year after the accident, living near the damaged reactor was associated with elevations in all indices of stress compared with control levels. Social support mediated these stress indices such that higher levels were associated with fewer psychological and behavioral symptoms of stress. Biochemical measures showed a different pattern of results.

In-flight measurement of propeller noise on the fuselage of an airplane

NASA Technical Reports Server (NTRS)

Pla, Frederic G.; Ranaudo, Richard; Woodward, Richard P.

1989-01-01

In-flight measurements of propeller noise on the fuselage of an OV-10A aircraft were obtained using a horizontal and a vertical microphone array. A wide range of flight conditions were tested including changes in angle of attack, sideslip angle, power coefficient, helical tip Mach number and advance ratio, and propeller direction of rotation. Results show a dependence of the level and directivity of the tones on the angle of attack and on the sideslip angle with the propeller direction of rotation, which is similar to results obtained in wind tunnel tests with advanced propeller designs. The level of the tones at each microphone increases with increasing angle of attack for inboard-down propeller rotation and decreases for inboard-up rotation. The level also increases with increasing slideslip angle for both propeller directions of rotation. Increasing the power coefficient results in a slight increase in the level of the tones. A strong shock wave is generated by the propeller blades even at relatively low helical tip Mach numbers resulting in high harmonic levels. As the helical tip Mach number and the advance ratio are increased, the level of the higher harmonics increases much faster than the level of the blade passage frequency.

The Motor and the Brake of the Trailing Leg in Human Walking: Leg Force Control Through Ankle Modulation and Knee Covariance

PubMed Central

Toney, Megan E.; Chang, Young-Hui

2016-01-01

Human walking is a complex task, and we lack a complete understanding of how the neuromuscular system organizes its numerous muscles and joints to achieve consistent and efficient walking mechanics. Focused control of select influential task-level variables may simplify the higher-level control of steady state walking and reduce demand on the neuromuscular system. As trailing leg power generation and force application can affect the mechanical efficiency of step-to-step transitions, we investigated how joint torques are organized to control leg force and leg power during human walking. We tested whether timing of trailing leg force control corresponded with timing of peak leg power generation. We also applied a modified uncontrolled manifold analysis to test whether individual or coordinated joint torque strategies most contributed to leg force control. We found that leg force magnitude was adjusted from step-to-step to maintain consistent leg power generation. Leg force modulation was primarily determined by adjustments in the timing of peak ankle plantar-flexion torque, while knee torque was simultaneously covaried to dampen the effect of ankle torque on leg force. We propose a coordinated joint torque control strategy in which the trailing leg ankle acts as a motor to drive leg power production while trailing leg knee torque acts as a brake to refine leg power production. PMID:27334888

Modified nonlinear amplifying loop mirror for mode-locked fibre oscillators with record-high energy and high-average-power pulsed output

NASA Astrophysics Data System (ADS)

Kobtsev, Sergey; Ivanenko, Alexey; Smirnov, Sergey; Kokhanovsky, Alexey

2018-02-01

The present work proposes and studies approaches for development of new modified non-linear amplifying loop mirror (NALM) allowing flexible and dynamic control of their non-linear properties within a relatively broad range of radiation powers. Using two independently pumped active media in the loop reflector constitutes one of the most promising approaches to development of better NALM with nonlinear properties controllable independently of the intra-cavity radiation power. This work reports on experimental and theoretical studies of the proposed redesigned NALM allowing both a higher level of energy parameters of output generated by mode-locked fibre oscillators and new possibilities of switching among different mode-locked regimes.

Flipped Classroom versus Traditional Textbook Instruction: Assessing Accuracy and Mental Effort at Different Levels of Mathematical Complexity

ERIC Educational Resources Information Center

Mattis, Kristina V.

2015-01-01

Flipped classrooms are an instructional technology trend mostly incorporated in higher education settings, with growing prominence in high school and middle school (Tucker in Leveraging the power of technology to create student-centered classrooms. Corwin, Thousand Oaks, 2012). Flipped classrooms are meant to effectively combine traditional and…

Competitiveness in the sawmills and wood preservation industry in the United States and Canada

Treesearch

Rao V Nagubadi; Daowei Zhang

2010-01-01

We examine relative prices, relative productivity levels, and competitiveness in the sawmills and wood preservation industry in the united states and Canada between 1958 and 2003 by using purchasing power parities and bilateral translog production function. Our results show that the competitiveness of the Canadian industy is facilitated by higher relative productivity...

Equalisation or Inflation? Social Class and Gender Differentials in England and Wales

ERIC Educational Resources Information Center

Sullivan, Alice; Heath, Anthony; Rothon, Catherine

2011-01-01

The Labour government elected in 1997, which lost power in 2010, was the longest serving Labour administration Britain has ever had. This period saw an enormous expansion of further and higher education, and an increase in the proportion of students achieving school-level qualifications. But have inequalities diminished as a result? We examine the…

An Examination of Global University Rankings as a New Mechanism Influencing Mission Differentiation: The UK Context

ERIC Educational Resources Information Center

O'Connell, Catherine

2015-01-01

Since their emergence a decade ago, global university rankings have become a powerful force in higher education internationally. The majority of research studies on global rankings have examined the effects at institutional and national levels. This study offers a valuable perspective on the ways rankings (and other international benchmarks) are…

Educational Policy-Making as Power Struggle in a Multi-Cultural Society: The Malaysian Case. Revised Draft.

ERIC Educational Resources Information Center

Hsu, Philip, Jr.

This essay demonstrates how politics affected educational policy making at the national level in Malaysia. A historical and social overview describes the country's ethnic diversity and the passage of legislation that was designed to promote universal access to education. The government's higher education policies are evaluated, based on a process…

Invisible Ink: An Analysis of Meaning Contained in Gender, Race, Performance, and Power Discourses

ERIC Educational Resources Information Center

Griggs, Susan A.

2012-01-01

The number of females in senior level leadership positions in higher education is substantially fewer than males. Yet female students in these same institutions represent over half the population (National Center for Educational Statistics, 2010). The leadership gender gap is a phenomenon that has undergone numerous studies in search of reasons…

Why weight? Modelling sample and observational level variability improves power in RNA-seq analyses.

PubMed

Liu, Ruijie; Holik, Aliaksei Z; Su, Shian; Jansz, Natasha; Chen, Kelan; Leong, Huei San; Blewitt, Marnie E; Asselin-Labat, Marie-Liesse; Smyth, Gordon K; Ritchie, Matthew E

2015-09-03

Variations in sample quality are frequently encountered in small RNA-sequencing experiments, and pose a major challenge in a differential expression analysis. Removal of high variation samples reduces noise, but at a cost of reducing power, thus limiting our ability to detect biologically meaningful changes. Similarly, retaining these samples in the analysis may not reveal any statistically significant changes due to the higher noise level. A compromise is to use all available data, but to down-weight the observations from more variable samples. We describe a statistical approach that facilitates this by modelling heterogeneity at both the sample and observational levels as part of the differential expression analysis. At the sample level this is achieved by fitting a log-linear variance model that includes common sample-specific or group-specific parameters that are shared between genes. The estimated sample variance factors are then converted to weights and combined with observational level weights obtained from the mean-variance relationship of the log-counts-per-million using 'voom'. A comprehensive analysis involving both simulations and experimental RNA-sequencing data demonstrates that this strategy leads to a universally more powerful analysis and fewer false discoveries when compared to conventional approaches. This methodology has wide application and is implemented in the open-source 'limma' package. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

Encouraging vehicle-to-grid (V2G) participation through premium tariff rates

NASA Astrophysics Data System (ADS)

Richardson, David B.

2013-12-01

The provision of vehicle-to-grid (V2G) services to an electric grid by electric vehicles (EVs) can potentially reduce the cost of vehicle ownership through revenue generation. Recent studies indicate that yearly vehicle profit from V2G may not be sufficient to induce widespread participation. This paper investigates the feasibility of a premium tariff rate for V2G power, similar to current feed-in-tariff (FIT) programs for renewable energy. Using Ontario, Canada as a case study, an hourly time-series model for a fleet of commuter EVs is created. Tariff rates for V2G peak power are calculated based on the same return on investment as the current FIT for renewable energy in Ontario. The tariff rates are competitive with the renewable energy tariffs, especially when EVs are allowed to provide ancillary services to the grid in addition to peak power. Despite the guaranteed rate of return, yearly vehicle profit is low. Two variations are considered to increase vehicle profit, thereby enhancing the attractiveness of V2G. A higher return on investment is favored over direct benefits offered to EV owners. A higher return on investment may be justifiable based on the higher level of risk inherent in V2G when compared to renewable energy.

Potential clinical impact of laser-accelerated beams in cancer ion therapy

NASA Astrophysics Data System (ADS)

Obcemea, Ceferino

2016-09-01

In this article, I present three advantages of plasma-accelerated ion beams for cancer therapy. I discuss how: 1. low-emittance and well-collimated beams are advantageous in proximal normal tissue-sparing; 2. highly-peaked quasi-monoenergetic beams are ideal for fast energy selection and switching in Pencil Beam Scanning (PBS) as a treatment delivery; 3. high fluence and ultra-short pulse delivery produce collective excitations in the medium and enhance the stopping power. This in turn produces denser ionization track signatures (spurs, blobs, etc.) in target tumors, higher linear energy transfer, higher Bragg peak, and higher radiobiological effectiveness at the micro-level.

Spring 2014 Internship Diffuser Data Analysis

NASA Technical Reports Server (NTRS)

Laigaie, Robert T.; Ryan, Harry M.

2014-01-01

J-2X engine testing on the A-2 test stand at the NASA John C. Stennis Space Center (SSC) has recently concluded. As part of that test campaign, the engine was operated at lower power levels in support of expanding the use of J-2X to other missions. However, the A-2 diffuser was not designed for engine testing at the proposed low power levels. To evaluate the risk of damage to the diffuser, computer simulations were created of the rocket engine exhaust plume inside the 50ft long, water-cooled, altitude-simulating diffuser. The simulations predicted that low power level testing would cause the plume to oscillate in the lower sections of the diffuser. This can possibly cause excessive vibrations, stress, and heat transfer from the plume to the diffuser walls. To understand and assess the performance of the diffuser during low power level engine testing, nine accelerometers and four strain gages were installed around the outer surface of the diffuser. The added instrumentation also allowed for the verification of the rocket exhaust plume computational model. Prior to engine hot-fire testing, a diffuser water-flow test was conducted to verify the proper operation of the newly installed instrumentation. Subsequently, two J-2X engine hot-fire tests were completed. Hot-Fire Test 1 was 11.5 seconds in duration, and accelerometer and strain data verified that the rocket engine plume oscillated in the lower sections of the diffuser. The accelerometers showed very different results dependent upon location. The diffuser consists of four sections, with Section 1 being closest to the engine nozzle and Section 4 being farthest from the engine nozzle. Section 1 accelerometers showed increased amplitudes at startup and shutdown, but low amplitudes while the diffuser was started. Section 3 accelerometers showed the opposite results with near zero G amplitudes prior to and after diffuser start and peak amplitudes to +/- 100G while the diffuser was started. Hot-Fire Test 1 strain gages showed different data dependent on section. Section 1 strains were small, and were in the range of 50 to 150 microstrain, which would result in stresses from 1.45 to 4.35 ksi. The yield stress of the material, A-285 Grade C Steel, is 29.7 ksi. Section 4 strain gages showed much higher values with strains peaking at 1600 microstrain. This strain corresponds to a stress of 46.41 ksi, which is in excess of the yield stress, but below the ultimate stress of 55 to 75 ksi. The decreased accelerations and strain in Section 1, and the increased accelerations and strain in Sections 3 and 4 verified the computer simulation prediction of increased plume oscillations in the lower sections of the diffuser. Hot-Fire Test 2 ran for a duration of 125 seconds. The engine operated at a slightly higher power level than Hot-Fire Test 1 for the initial 35 seconds of the test. After 35 seconds the power level was lowered to Hot-Fire Test 1 levels. The acceleration and strain data for Hot-Fire Test 2 was similar during the initial part of the test. However, just prior to the engine being lowered to the Hot-Fire Test 1 power level, the strain gage data in Section 4 showed a large decrease to strains near zero microstrain from their peak at 1500 microstrain. Future work includes further strain and acceleration data analysis and evaluation.

Comparison of Physical and Physiological Profiles in Elite and Amateur Young Wrestlers.

PubMed

Demirkan, Erkan; Koz, Mitat; Kutlu, Mehmet; Favre, Mike

2015-07-01

The aim of this study is to examine the physical and physiological determinants of wrestling success between elite and amateur male wrestlers. The wrestlers (N = 126) were first assigned to 3 groups based on their competitive level (top elite, elite, and amateur) and then to 6 groups according to their body mass (light, middle, and heavy weight) and their competitive level (elite and amateur). Top elite and elite wrestlers had significantly (p ≤ 0.05) more training experiences and maximal oxygen uptake compared with the amateur group. In separating weight classes, light- and middle-weight elite (MWE) wrestlers had significantly (p ≤ 0.05) more training experience (7-20%) compared with the light- and middle-weight amateur (MWA) wrestlers. No significant differences were detected between elite and amateur groups (light-, middle-, and heavy-weight wrestlers) for age, body mass, height, body mass index, and body fat (p > 0.05), with the exception of height for heavy wrestlers. Leg average and peak power values (in watts and watts per kilogram) in MWE were higher than MWA (6.5 and 13%, p ≤ 0.05). Relative leg average power value in heavy-weight elite (HWE) (in watts per kilogram) was higher than heavy-weight amateur (HWA) (9.6%, p ≤ 0.05). It was seen that elite wrestlers in MWE and HWE statistically possessed a higher V̇O2max (12.5 and 11.4%, respectively) than amateur middle- and heavy-weight wrestlers (p ≤ 0.05). The results of this study suggest that training experience, aerobic endurance, and anaerobic power and capacity will give a clear advantage for the wrestlers to take part in the elite group.

Spatial and seasonal variations, sources, air-soil exchange, and carcinogenic risk assessment for PAHs and PCBs in air and soil of Kutahya, Turkey, the province of thermal power plants.

PubMed

Dumanoglu, Yetkin; Gaga, Eftade O; Gungormus, Elif; Sofuoglu, Sait C; Odabasi, Mustafa

2017-02-15

Atmospheric and concurrent soil samples were collected during winter and summer of 2014 at 41 sites in Kutahya, Turkey to investigate spatial and seasonal variations, sources, air-soil exchange, and associated carcinogenic risks of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). The highest atmospheric and soil concentrations were observed near power plants and residential areas, and the wintertime concentrations were generally higher than ones measured in summer. Spatial distribution of measured ambient concentrations and results of the factor analysis showed that the major contributing PAH sources in Kutahya region were the coal combustion for power generation and residential heating (48.9%), and diesel and gasoline exhaust emissions (47.3%) while the major PCB sources were the coal (thermal power plants and residential heating) and wood combustion (residential heating) (45.4%), and evaporative emissions from previously used technical PCB mixtures (34.7%). Results of fugacity fraction calculations indicated that the soil and atmosphere were not in equilibrium for most of the PAHs (88.0% in winter, 87.4% in summer) and PCBs (76.8% in winter, 83.8% in summer). For PAHs, deposition to the soil was the dominant mechanism in winter while in summer volatilization was equally important. For PCBs, volatilization dominated in summer while deposition was higher in winter. Cancer risks associated with inhalation and accidental soil ingestion of soil were also estimated. Generally, the estimated carcinogenic risks were below the acceptable risk level of 10 -6 . The percentage of the population exceeding the acceptable risk level ranged from <1% to 16%, except, 32% of the inhalation risk levels due to PAH exposure in winter at urban/industrial sites were >10 -6 . Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of kilning on the antioxidant and pro-oxidant activities of pale malts.

PubMed

Woffenden, Helen M; Ames, Jennifer M; Chandra, Sachin; Anese, Monica; Nicoli, M Cristina

2002-08-14

Pale malts were prepared using standard and rapid kilning regimes that differed in the temperature and moisture profiles in the kiln. Samples were taken over the last 9 h of kilning, that is, at 18, 20, 22, 25, and 27 h. Antioxidant activity, assessed by redox potential, scavenging of the 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS*+), and ferric reducing/antioxidant power (FRAP), increased at moisture levels below 6.7% for both regimes. The 27 h malt exposed to the rapid regime (moisture content of 4.8%) had a higher activity than the 27 h standard regime sample (moisture content of 4.8%). None of the malts scavenged oxygen. Pro-oxidant activity profiles were different for the malts obtained using each regime and, at 27 h, the rapid procedure gave malt with higher activity. Levels of (+)-catechin and ferulic acid (the most abundant phenolic compounds identified) generally increased as the moisture content of malt fell below 6.7%. Differences in antioxidant and pro-oxidant activities of the 27 h malts are partly attributed to the Maillard reaction, as evidenced by lower L* and higher b* values and higher levels of Maillard-derived flavor compounds, in the sample obtained by the rapid procedure. Levels of lipid-derived flavor compounds were significantly higher after 27 h of kilning using the rapid procedure.

Pump dependence of the dynamics of quantum dot based waveguide absorbers

NASA Astrophysics Data System (ADS)

Viktorov, Evgeny A.; Erneux, Thomas; Piwonski, Tomasz; Pulka, Jaroslaw; Huyet, Guillaume; Houlihan, John

2012-06-01

The nonlinear two stage recovery of quantum dot based reverse-biased waveguide absorbers is investigated experimentally and analytically as a function of the initial ground state occupation probability of the dot. The latter is controlled experimentally by the pump pulse power. The slow stage of the recovery is exponential and its basic timescale is independent of pump power. The fast stage of the recovery is a logistic function which we analyze in detail. The relative strength of slow to fast components is highlighted and the importance of higher order absorption processes at the highest pump level is demonstrated.

An all-silicon passive optical diode.

PubMed

Fan, Li; Wang, Jian; Varghese, Leo T; Shen, Hao; Niu, Ben; Xuan, Yi; Weiner, Andrew M; Qi, Minghao

2012-01-27

A passive optical diode effect would be useful for on-chip optical information processing but has been difficult to achieve. Using a method based on optical nonlinearity, we demonstrate a forward-backward transmission ratio of up to 28 decibels within telecommunication wavelengths. Our device, which uses two silicon rings 5 micrometers in radius, is passive yet maintains optical nonreciprocity for a broad range of input power levels, and it performs equally well even if the backward input power is higher than the forward input. The silicon optical diode is ultracompact and is compatible with current complementary metal-oxide semiconductor processing.

Influence of polygenic risk scores on lipid levels and dyslipidemia in a psychiatric population receiving weight gain-inducing psychotropic drugs.

PubMed

Delacrétaz, Aurélie; Lagares Santos, Patricia; Saigi Morgui, Nuria; Vandenberghe, Frederik; Glatard, Anaïs; Gholam-Rezaee, Mehdi; von Gunten, Armin; Conus, Philippe; Eap, Chin B

2017-12-01

Dyslipidemia represents a major health issue in psychiatry. We determined whether weighted polygenic risk scores (wPRSs) combining multiple single-nucleotide polymorphisms (SNPs) associated with lipid levels in the general population are associated with lipid levels [high-density lipoprotein (HDL), low-density lipoprotein (LDL), total cholesterol (TC), and triglycerides] and/or dyslipidemia in patients receiving weight gain-inducing psychotropic drugs. We also determined whether genetics improve the predictive power of dyslipidemia. The influence of wPRS on lipid levels was firstly assessed in a discovery psychiatric sample (n=332) and was then tested for replication in an independent psychiatric sample (n=140). The contribution of genetic markers to predict dyslipidemia was evaluated in the combined psychiatric sample. wPRSs were significantly associated with the four lipid traits in the discovery (P≤0.02) and in the replication sample (P≤0.03). Patients whose wPRS was higher than the median wPRS had significantly higher LDL, TC, and triglyceride levels (0.20, 0.32 and 0.26 mmol/l, respectively; P≤0.004) and significantly lower HDL levels (0.13 mmol/l; P<0.0001) compared with others. Adding wPRS to clinical data significantly improved dyslipidemia prediction of HDL (P=0.03) and a trend for improvement was observed for the prediction of TC dyslipidemia (P=0.08). Population-based wPRSs have thus significant effects on lipid levels in the psychiatric population. As genetics improved the predictive power of dyslipidemia development, only 24 patients need to be genotyped to prevent the development of one case of HDL hypocholesterolemia. If confirmed by further prospective investigations, the present results could be used for individualizing psychotropic treatment.

Wholesale Electricity Market Design with Increasing Levels of Renewable Generation: Incentivizing Flexibility in System Operations

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

Ela, Erik; Milligan, Michael; Bloom, Aaron

This paper discusses the importance and challenges of incentivizing flexibility during short-term operations of the bulk power system due to the increasing variability and uncertainty from growing penetrations of variable generation (VG). Operational flexibility can refer to many aspects of a resource's capability to support the power system, such as the speed, range, and duration of power output, as well as the ability to autonomously respond to frequency or voltage changes. Inefficient utilization of existing flexibility, or unwillingness of resources to provide flexibility, can compromise system reliability by not meeting the changing net load, and it can also lead tomore » higher costs when an inefficient use of flexibility resources occurs. There are many existing characteristics of market design that incentivize flexibility in some manner. How they incentivize the provision of flexibility as well as the level of flexibility is still debated. We explore some of these existing market designs, as well as new market mechanisms, such as pay-for-performance regulating reserve and flexible ramping products, that aim to explicitly incentivize the provision of more flexibility to the system, particularly as a result of increasing VG penetration levels.« less

Biomechanical aspects of segmented arch mechanics combined with power arm for controlled anterior tooth movement: A three-dimensional finite element study.

PubMed

Ozaki, Hiroya; Tominaga, Jun-Ya; Hamanaka, Ryo; Sumi, Mayumi; Chiang, Pao-Chang; Tanaka, Motohiro; Koga, Yoshiyuki; Yoshida, Noriaki

2015-01-01

The porpose of this study was to determine the optimal length of power arms for achieving controlled anterior tooth movement in segmented arch mechanics combined with power arm. A three-dimensional finite element method was applied for the simulation of en masse anterior tooth retraction in segmented power arm mechanics. The type of tooth movement, namely, the location of center of rotation of the maxillary central incisor in association with power arm length, was calculated after the retraction force was applied. When a 0.017 × 0.022-in archwire was inserted into the 0.018-in slot bracket, bodily movement was obtained at 9.1 mm length of power arm, namely, at the level of 1.8 mm above the center of resistance. In case a 0.018 × 0.025-in full-size archwire was used, bodily movement of the tooth was produced at the power arm length of 7.0 mm, namely, at the level of 0.3 mm below the center of resistance. Segmented arch mechanics required shorter length of power arms for achieving any type of controlled anterior tooth movement as compared to sliding mechanics. Therefore, this space closing mechanics could be widely applied even for the patients whose gingivobuccal fold is shallow. The segmented arch mechanics combined with power arm could provide higher amount of moment-to-force ratio sufficient for controlled anterior tooth movement without generating friction, and vertical forces when applying retraction force parallel to the occlusal plane. It is, therefore, considered that the segmented power arm mechanics has a simple appliance design and allows more efficient and controllable tooth movement.

Gender differences in power production, energetic capacity and efficiency of elite cross‑country skiers during whole‑body, upper‑body, and arm poling.

PubMed

Hegge, Ann Magdalen; Bucher, Elias; Ettema, Gertjan; Faude, Oliver; Holmberg, Hans-Christer; Sandbakk, Øyvind

2016-02-01

To characterize gender differences in power output, energetic capacity and exercise efficiency during whole-body (WP), upper-body (UP), and arm poling (AP). Ten male and ten female elite cross-country skiers, matched for international performance level, completed three incremental submaximal tests and a 3-min self-paced performance test on a Concept2 SkiErg. Power output, cardiorespiratory and kinematic variables were monitored. Body composition was determined by dual-energy X-ray absorptiometry. The men demonstrated 87, 97 and 103% higher power output, and 51, 65 and 71% higher VO2peak (L min(−1)) than the women during WP, UP and AP, respectively, while utilizing ~10% more of their running VO2max in all modes (all P < 0.001). The men had 35, 38 and 59% more lean mass in the whole body, upper body and arms (all P < 0.001). The men exhibited greater shoulder and elbow extension at the start of poling and greater trunk flexion at the end of poling (all P < 0.05). The relationship between VO2 and power output did not differ between the men and women. Gender differences in power production and peak aerobic capacity increased sequentially from WP to UP to AP, coinciding with a greater portion of the muscle mass in the arms of the men. Although the men and women employed each poling technique differently, the estimated efficiency of double poling was independent of gender.

A Hermeneutic Phenomenology of Graduate Education Students' Understandings of Instructor Power in a Higher Education Classroom

ERIC Educational Resources Information Center

Delgado, Antonio

2012-01-01

Higher education is a distribution center of knowledge and economic, social, and cultural power (Cervero & Wilson, 2001). A critical approach to understanding a higher education classroom begins with recognizing the instructor's position of power and authority (Tisdell, Hanley, & Taylor, 2000). The power instructors wield exists…

Controlled power delivery for super-resolution imaging of biological samples using digital micromirror device

NASA Astrophysics Data System (ADS)

Valiya Peedikakkal, Liyana; Cadby, Ashley

2017-02-01

Localization based super resolution images of a biological sample is generally achieved by using high power laser illumination with long exposure time which unfortunately increases photo-toxicity of a sample, making super resolution microscopy, in general, incompatible with live cell imaging. Furthermore, the limitation of photobleaching reduces the ability to acquire time lapse images of live biological cells using fluorescence microscopy. Digital Light Processing (DLP) technology can deliver light at grey scale levels by flickering digital micromirrors at around 290 Hz enabling highly controlled power delivery to samples. In this work, Digital Micromirror Device (DMD) is implemented in an inverse Schiefspiegler telescope setup to control the power and pattern of illumination for super resolution microscopy. We can achieve spatial and temporal patterning of illumination by controlling the DMD pixel by pixel. The DMD allows us to control the power and spatial extent of the laser illumination. We have used this to show that we can reduce the power delivered to the sample to allow for longer time imaging in one area while achieving sub-diffraction STORM imaging in another using higher power densities.

Molecular and neurodevelopmental benefits to children of closure of a coal burning power plant in China.

PubMed

Tang, Deliang; Lee, Joan; Muirhead, Loren; Li, Ting Yu; Qu, Lirong; Yu, Jie; Perera, Frederica

2014-01-01

Polycyclic aromatic hydrocarbons (PAH) are major toxic air pollutants released during incomplete combustion of coal. PAH emissions are especially problematic in China because of their reliance on coal-powered energy. The prenatal period is a window of susceptibility to neurotoxicants. To determine the health benefits of reducing air pollution related to coal-burning, we compared molecular biomarkers of exposure and preclinical effects in umbilical cord blood to neurodevelopmental outcomes from two successive birth cohorts enrolled before and after a highly polluting, coal-fired power plant in Tongliang County, China had ceased operation. Women and their newborns in the two successive cohorts were enrolled at the time of delivery. We measured PAH-DNA adducts, a biomarker of PAH-exposure and DNA damage, and brain-derived neurotrophic factor (BDNF), a protein involved in neuronal growth, in umbilical cord blood. At age two, children were tested using the Gesell Developmental Schedules (GDS). The two cohorts were compared with respect to levels of both biomarkers in cord blood as well as developmental quotient (DQ) scores across 5 domains. Lower levels of PAH-DNA adducts, higher concentrations of the mature BDNF protein (mBDNF) and higher DQ scores were seen in the 2005 cohort enrolled after closure of the power plant. In the two cohorts combined, PAH-DNA adducts were inversely associated with mBDNF as well as scores for motor (p = 0.05), adaptive (p = 0.022), and average (p = 0.014) DQ. BDNF levels were positively associated with motor (p = 0.018), social (p = 0.001), and average (p = 0.017) DQ scores. The findings indicate that the closure of a coal-burning plant resulted in the reduction of PAH-DNA adducts in newborns and increased mBDNF levels that in turn, were positively associated with neurocognitive development. They provide further evidence of the direct benefits to children's health as a result of the coal plant shut down, supporting clean energy and environmental policies in China and elsewhere.

Development and implementation of a dynamic TES dispatch control component in a PV-CSP techno-economic performance modelling tool

NASA Astrophysics Data System (ADS)

Hansson, Linus; Guédez, Rafael; Larchet, Kevin; Laumert, Bjorn

2017-06-01

The dispatchability offered by thermal energy storage (TES) in concentrated solar power (CSP) and solar hybrid plants based on such technology presents the most important difference compared to power generation based only on photovoltaics (PV). This has also been one reason for recent hybridization efforts of the two technologies and the creation of Power Purchase Agreement (PPA) payment schemes based on offering higher payment multiples during daily hours of higher (peak or priority) demand. Recent studies involving plant-level thermal energy storage control strategies are however to a large extent based on pre-determined approaches, thereby not taking into account the actual dynamics of thermal energy storage system operation. In this study, the implementation of a dynamic dispatch strategy in the form of a TRNSYS controller for hybrid PV-CSP plants in the power-plant modelling tool DYESOPT is presented. In doing this it was attempted to gauge the benefits of incorporating a day-ahead approach to dispatch control compared to a fully pre-determined approach determining hourly dispatch only once prior to annual simulation. By implementing a dynamic strategy, it was found possible to enhance technical and economic performance for CSP-only plants designed for peaking operation and featuring low values of the solar multiple. This was achieved by enhancing dispatch control, primarily by taking storage levels at the beginning of every simulation day into account. The sequential prediction of the TES level could therefore be improved, notably for evaluated plants without integrated PV, for which the predicted storage levels deviated less than when PV was present in the design. While also featuring dispatch performance gains, optimal plant configurations for hybrid PV-CSP was found to present a trade-off in economic performance in the form of an increase in break-even electricity price when using the dynamic strategy which was offset to some extent by a reduction in upfront investment cost. An increase in turbine starts for the implemented strategy however highlights that this is where further improvements can be made.

Resonant AC power system proof-of-concept test program

NASA Technical Reports Server (NTRS)

Wappes, Loran J.

1986-01-01

Proof-of-concept testing was performed on a 20-kHz, resonant power system breadboard from 1981 through 1985. The testing began with the evaluation of a single, 1.0-kW resonant inverter and progressed to the testing of breadboard systems with higher power levels and more capability. The final breadboard configuration tested was a 25.0-kW breadboard with six inverters providing power to three user-interface modules over a 50-meter, 20-kHz bus. The breadboard demonstrated the ability to synchronize multiple resonant inverters to power a common bus. Single-phase and three-phase 20-kHz power distribution was demonstrated. Simple conversion of 20-kHz to dc and variable-frequency ac was demonstrated as was bidirectional power flow between 20-kHz and dc. Steady state measurements of efficiency, power-factor tolerance, and conducted emissions and conducted susceptibility were made. In addition, transient responses were recorded for such conditions as start up, shut down, load changes. The results showed the 20-kHz resonant system to be a desirable technology for a spacecraft power management and distribution system with multiple users and a utility-type bus.

Cultural variation in seasonal depression: cross-national differences in winter versus summer patterns of seasonal affective disorder.

PubMed

Kasof, Joseph

2009-05-01

Research suggests that two dimensions of national culture, individualism-collectivism and power distance, predict affective responses to the seasonally varying levels of ambient sunlight that may underlie regular cycles of mood and behavior in Seasonal Affective Disorder (SAD). Specifically, negative affect is predicted by the diminished sunlight of fall-winter in countries higher in individualism and lower in power distance, and by the increased sunlight of spring-summer in countries lower in individualism and higher in power distance. This study tests whether individualism correlates positively, and power distance negatively, with the frequency of winter-SAD relative to that of summer-SAD. A search for studies reporting frequencies of both winter-SAD and summer-SAD identified 55 samples encompassing 18 countries and 38,408 participants, including 1931 with SAD. The frequency of winter-SAD, relative to that of summer-SAD, correlated positively with individualism (r=.67, p=.001) and negatively with power distance (r=-.72, p=.0001). Countries in which winter-SAD was more common than summer-SAD were significantly more individualistic and less power-distant than countries in which summer-SAD was more common than winter-SAD. Results survived various tests of threats to validity. The study is limited by the quantity, quality, diversity, and representativeness of the research under review and by its correlational design. Individualism and power distance are strongly related to the relative prevalence of winter-SAD and summer-SAD. Culture may play an important but previously overlooked role in the etiology of SAD.

Distinctive inflammatory profile between acute focal bacterial nephritis and acute pyelonephritis in children.

PubMed

Mizutani, Makoto; Hasegawa, Shunji; Matsushige, Takeshi; Ohta, Naoki; Kittaka, Setsuaki; Hoshide, Madoka; Kusuda, Takeshi; Takahashi, Kazumasa; Ichihara, Kiyoshi; Ohga, Shouichi

2017-11-01

Acute focal bacterial nephritis (AFBN) is a severe form of upper urinary tract infection (UTI) with neurological manifestations and focal renal mass lesions on computed tomography (CT). Prolonged antibiotic therapy may improve the renal outcome, but the early differential diagnosis of AFBN from acute pyelonephritis (APN) is challenging. We searched for effective biomarkers of AFBN based on the pathophysiology of upper UTIs. Of 52 upper UTI cases treated at Yamaguchi University between 2009 and 2016, 38 pediatric patients with AFBN (n=17) or APN (n=21) who underwent ultrasonography and/or CT were enrolled. The clinical data and serum cytokine concentrations were analyzed to differentiate AFBN from APN. AFBN patients tended to be older, and have a higher body temperature, longer febrile period, more frequent neurological symptoms, higher immature neutrophil count, lower lymphocyte count, higher procalcitonin and urine β 2 -microglobulin levels. AFBN patients showed higher serum levels of IFN-γ, IL-6, IL-10 and soluble TNF-receptor 1 (sTNFR1) (all p<0.05). Although the cytokine levels were variably correlated among each other, multiple logistic regression analysis revealed that combination of IFN-γ and IL-6 levels were most relevant for distinguishing AFBN from APN. The discriminant power of the logistic equation was 0.86 in terms of the area under the curve by the ROC analysis. Circulating 4 out of 7 cytokines in AFBN patients were at higher levels compared with those in APN patients. IFN-γ and IL-6 levels might most effectively distinguish AFBN from APN. Copyright © 2017 Elsevier Ltd. All rights reserved.

Materials Development for Next Generation Optical Fiber

PubMed Central

Ballato, John; Dragic, Peter

2014-01-01

Optical fibers, the enablers of the Internet, are being used in an ever more diverse array of applications. Many of the rapidly growing deployments of fibers are in high-power and, particularly, high power-per-unit-bandwidth systems where well-known optical nonlinearities have historically not been especially consequential in limiting overall performance. Today, however, nominally weak effects, most notably stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS) are among the principal phenomena restricting continued scaling to higher optical power levels. In order to address these limitations, the optical fiber community has focused dominantly on geometry-related solutions such as large mode area (LMA) designs. Since such scattering, and all other linear and nonlinear optical phenomena including higher order mode instability (HOMI), are fundamentally materials-based in origin, this paper unapologetically advocates material solutions to present and future performance limitations. As such, this paper represents a ‘call to arms’ for material scientists and engineers to engage in this opportunity to drive the future development of optical fibers that address many of the grand engineering challenges of our day. PMID:28788683

Enhanced power factor of higher manganese silicide via melt spin synthesis method

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

Shi, Xiaoya; Li, Qiang, E-mail: liqiang@bnl.gov; Shi, Xun

We report on the thermoelectric properties of the higher manganese silicide MnSi{sub 1.75} synthesized by means of a one-step non-equilibrium method. The ultrahigh cooling rate generated from the melt-spin technique is found to be effective in reducing second phases, which are inevitable during the traditional solid state diffusion processes. Aside from being detrimental to thermoelectric properties, second phases skew the revealing of the intrinsic properties of this class of materials, for example, the optimal level of carrier concentration. With this melt-spin sample, we are able to formulate a simple model based on a single parabolic band that can well describemore » the carrier concentration dependence of the Seebeck coefficient and power factor of the data reported in the literature. An optimal carrier concentration around 5 × 10{sup 20 }cm{sup −3} at 300 K is predicted according to this model. The phase-pure melt-spin sample shows the largest power factor at high temperature, resulting in the highest zT value among the three samples in this paper.« less

Nurses in OR are more assertive than radiographers.

PubMed

Johnson, L

1993-01-01

This study investigated two hypotheses: that there is a positive correlation between assertiveness and self-esteem, and that nurses rate lower than non-nurses on the constructs. A self-report survey incorporating scales for general assertiveness, situationally-specific assertiveness, global self-esteem and differentiated self-esteem was utilised. For the sample of 83 operating room nurses and 81 radiographers, correlations significant at the p < .001 level between the respective scales supported the first hypothesis. Analysis of variance yielded no significant differences between the two groups on either self-esteem measures or general assertiveness, with the nurses scoring significantly higher than radiographers on the situationally-specific assertiveness scale. Findings challenge the stereotype of the 'shrinking violet' nurse. Additional analysis revealed that the power component of differentiated self-esteem had a higher correlation with global self-esteem and with both assertiveness measures than any other component. Further, the operating room nurses were significantly more power-oriented than radiographers. The pre-eminence of power in the findings suggests that assertiveness and self-esteem are issues relating to the empowerment of nurses.

Systematic Evaluation of Stochastic Methods in Power System Scheduling and Dispatch with Renewable Energy

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

Wang, Yishen; Zhou, Zhi; Liu, Cong

2016-08-01

As more wind power and other renewable resources are being integrated into the electric power grid, the forecast uncertainty brings operational challenges for the power system operators. In this report, different operational strategies for uncertainty management are presented and evaluated. A comprehensive and consistent simulation framework is developed to analyze the performance of different reserve policies and scheduling techniques under uncertainty in wind power. Numerical simulations are conducted on a modified version of the IEEE 118-bus system with a 20% wind penetration level, comparing deterministic, interval, and stochastic unit commitment strategies. The results show that stochastic unit commitment provides amore » reliable schedule without large increases in operational costs. Moreover, decomposition techniques, such as load shift factor and Benders decomposition, can help in overcoming the computational obstacles to stochastic unit commitment and enable the use of a larger scenario set to represent forecast uncertainty. In contrast, deterministic and interval unit commitment tend to give higher system costs as more reserves are being scheduled to address forecast uncertainty. However, these approaches require a much lower computational effort Choosing a proper lower bound for the forecast uncertainty is important for balancing reliability and system operational cost in deterministic and interval unit commitment. Finally, we find that the introduction of zonal reserve requirements improves reliability, but at the expense of higher operational costs.« less

Low-Cost energy contraption design using playground seesaw

NASA Astrophysics Data System (ADS)

Banlawe, I. A. P.; Acosta, N. J. E. L.

2017-05-01

The study was conducted at Western Philippines University, San Juan, Aborlan, Palawan. The study used the mechanical motion of playground seesaw as a means to produce electrical energy. The study aimed to design a low-cost prototype energy contraption using playground seesaw using locally available and recycled materials, to measure the voltage, current and power outputs produced at different situations and estimate the cost of the prototype. Using principle of pneumatics, two hand air pumps were employed on the two end sides of the playground seesaw and the mechanical motion of the seesaw up and down produces air that is used to rotate a DC motor to produce electrical energy. This electricity can be utilized for powering basic or low-power appliances. There were two trials of testing, each trial tests the different pressure level of the air tank and tests the opening of on-off valve (Full open and half open) when the compressed air was released. Results showed that all pressure level at full open produced significantly higher voltage, than the half open. However, the mean values of the current and power produced in all pressure level at full and half open have negligible variation. These results signify that the energy contraption using playground seesaw is an alternative viable source of electrical energy in the playgrounds, parks and other places and can be used as an auxiliary or back-up source for electricity.

Noise reduction in a Mach 5 wind tunnel with a rectangular rod-wall sound shield

NASA Technical Reports Server (NTRS)

Creel, T. R., Jr.; Keyes, J. W.; Beckwith, I. E.

1980-01-01

A rod wall sound shield was tested over a range of Reynolds numbers of 0.5 x 10 to the 7th power to 8.0 x 10 to the 7th power per meter. The model consisted of a rectangular array of longitudinal rods with boundary-layer suction through gaps between the rods. Suitable measurement techniques were used to determine properties of the flow and acoustic disturbance in the shield and transition in the rod boundary layers. Measurements indicated that for a Reynolds number of 1.5 x 10 to the 9th power the noise in the shielded region was significantly reduced, but only when the flow is mostly laminar on the rods. Actual nozzle input noise measured on the nozzle centerline before reflection at the shield walls was attenuated only slightly even when the rod boundary layer were laminar. At a lower Reynolds number, nozzle input noise at noise levels in the shield were still too high for application to a quiet tunnel. At Reynolds numbers above 2.0 x 10 the the 7th power per meter, measured noise levels were generally higher than nozzle input levels, probably due to transition in the rod boundary layers. The small attenuation of nozzle input noise at intermediate Reynolds numbers for laminar rod layers at the acoustic origins is apparently due to high frequencies of noise.

Potential Occupational Exposures and Health Risks Associated with Biomass-Based Power Generation.

PubMed

Rohr, Annette C; Campleman, Sharan L; Long, Christopher M; Peterson, Michael K; Weatherstone, Susan; Quick, Will; Lewis, Ari

2015-07-22

Biomass is increasingly being used for power generation; however, assessment of potential occupational health and safety (OH&S) concerns related to usage of biomass fuels in combustion-based generation remains limited. We reviewed the available literature on known and potential OH&S issues associated with biomass-based fuel usage for electricity generation at the utility scale. We considered three potential exposure scenarios--pre-combustion exposure to material associated with the fuel, exposure to combustion products, and post-combustion exposure to ash and residues. Testing of dust, fungal and bacterial levels at two power stations was also undertaken. Results indicated that dust concentrations within biomass plants can be extremely variable, with peak levels in some areas exceeding occupational exposure limits for wood dust and general inhalable dust. Fungal spore types, identified as common environmental species, were higher than in outdoor air. Our review suggests that pre-combustion risks, including bioaerosols and biogenic organics, should be considered further. Combustion and post-combustion risks appear similar to current fossil-based combustion. In light of limited available information, additional studies at power plants utilizing a variety of technologies and biomass fuels are recommended.

Effect of 940 nm low-level laser therapy on osteogenesis in vitro

NASA Astrophysics Data System (ADS)

Jawad, Mohammed Mahmood; Husein, Adam; Azlina, Ahmad; Alam, Mohammad Khursheed; Hassan, Rozita; Shaari, Rumaizi

2013-12-01

Bone regeneration is essential in medical treatment, such as in surgical bone healing and orthodontics. The aim of this study is to examine the effect of different powers of 940 nm diode low-level laser treatment (LLLT) on osteoblast cells during their proliferation and differentiation stages. A human fetal osteoblast cell line was cultured and treated with LLLT. The cells were divided into experimental groups according to the power delivered and periods of exposure per day for each laser power. The (3-(4,5-dimethylthiazol-2yl)-2,5 diphenyl tetrazolium bromide) (MTT) assay was used to determine cell proliferation. Both alkaline phosphatase and osteocalcin activity assays were assessed for cell differentiation. All treatment groups showed a significant increase in cell proliferation and differentiation compared to the control group. Regarding the exposure time, the subgroups treated with the LLLT for 6 min showed higher proliferation and differentiation rates for the powers delivered, the 300-mW LLLT group significantly increased the amount of cell proliferation. By contrast, the 100 and 200 mW groups showed significantly greater amounts of cell differentiation. These results suggest that the use of LLLT may play an important role in stimulating osteoblast cells for improved bone formation.

Potential Occupational Exposures and Health Risks Associated with Biomass-Based Power Generation

PubMed Central

Rohr, Annette C.; Campleman, Sharan L.; Long, Christopher M.; Peterson, Michael K.; Weatherstone, Susan; Quick, Will; Lewis, Ari

2015-01-01

Biomass is increasingly being used for power generation; however, assessment of potential occupational health and safety (OH&S) concerns related to usage of biomass fuels in combustion-based generation remains limited. We reviewed the available literature on known and potential OH&S issues associated with biomass-based fuel usage for electricity generation at the utility scale. We considered three potential exposure scenarios—pre-combustion exposure to material associated with the fuel, exposure to combustion products, and post-combustion exposure to ash and residues. Testing of dust, fungal and bacterial levels at two power stations was also undertaken. Results indicated that dust concentrations within biomass plants can be extremely variable, with peak levels in some areas exceeding occupational exposure limits for wood dust and general inhalable dust. Fungal spore types, identified as common environmental species, were higher than in outdoor air. Our review suggests that pre-combustion risks, including bioaerosols and biogenic organics, should be considered further. Combustion and post-combustion risks appear similar to current fossil-based combustion. In light of limited available information, additional studies at power plants utilizing a variety of technologies and biomass fuels are recommended. PMID:26206568

Educational Status of the Married Women and Their Participation at Household Decision Making in Rural Bangladesh

NASA Astrophysics Data System (ADS)

Chanda, Sanjoy Kumar; Howlader, Hasan; Nahar, Nasrin

2012-11-01

The key focus of this study is to explain the level of education of married women and their participation in decision making process at different arena of rural household. To find out the nature of the reality, survey research design was used for this study. The study was conducted at Maharajpur, one of the unions of Jhenidah district in Bangladesh in 2011. The respondents of the study consisted of 120 married women who were purposively selected from the study area. Data were collected through direct interview method using an interview schedule. Data were shown on univariate, as well as bivariate statistical tables and then analyzed. The study reveals that a significant percent (93.3) of higher level of education completed women had their consent of getting married whereas no consent was made by illiterate women. In the same way 46.7 percent higher level of education completed women had high level of purchasing power in compare to illiterate (.0%) and primary (14.6%) level completed women for the same level of purchasing. In the political decision making 86.7 percent higher level of education completed women had own consent to vote for election in contrast to 77.8 percent illiterate and 70.7 percent primary level completed women were influenced by their husband to decide voting.

Impact of Different Tidal Volume Levels at Low Mechanical Power on Ventilator-Induced Lung Injury in Rats.

PubMed

Moraes, Lillian; Silva, Pedro L; Thompson, Alessandra; Santos, Cintia L; Santos, Raquel S; Fernandes, Marcos V S; Morales, Marcelo M; Martins, Vanessa; Capelozzi, Vera L; de Abreu, Marcelo G; Pelosi, Paolo; Rocco, Patricia R M

2018-01-01

Tidal volume (V T ) has been considered the main determinant of ventilator-induced lung injury (VILI). Recently, experimental studies have suggested that mechanical power transferred from the ventilator to the lungs is the promoter of VILI. We hypothesized that, as long as mechanical power is kept below a safe threshold, high V T should not be injurious. The present study aimed to investigate the impact of different V T levels and respiratory rates (RR) on lung function, diffuse alveolar damage (DAD), alveolar ultrastructure, and expression of genes related to inflammation [interleukin (IL)-6], alveolar stretch (amphiregulin), epithelial [club cell secretory protein (CC)16] and endothelial [intercellular adhesion molecule (ICAM)-1] cell injury, and extracellular matrix damage [syndecan-1, decorin, and metalloproteinase (MMP)-9] in experimental acute respiratory distress syndrome (ARDS) under low-power mechanical ventilation. Twenty-eight Wistar rats received Escherichia coli lipopolysaccharide intratracheally. After 24 h, 21 animals were randomly assigned to ventilation (2 h) with low mechanical power at three different V T levels ( n = 7/group): (1) V T = 6 mL/kg and RR adjusted to normocapnia; (2) V T = 13 mL/kg; and 3) V T = 22 mL/kg. In the second and third groups, RR was adjusted to yield low mechanical power comparable to that of the first group. Mechanical power was calculated as [(Δ[Formula: see text]/Est, L )/2]× RR (ΔP, L = transpulmonary driving pressure, Est, L = static lung elastance). Seven rats were not mechanically ventilated (NV) and were used for molecular biology analysis. Mechanical power was comparable among groups, while V T gradually increased. ΔP, L and mechanical energy were higher in V T = 22 mL/kg than V T = 6 mL/kg and V T = 13 mL/kg ( p < 0.001 for both). Accordingly, DAD score increased in V T = 22 mL/kg compared to V T = 6 mL/kg and V T = 13 mL/kg [23(18.5-24.75) vs. 16(12-17.75) and 16(13.25-18), p < 0.05, respectively]. V T = 22 mL/kg was associated with higher IL-6, amphiregulin, CC16, MMP-9, and syndecan-1 mRNA expression and lower decorin expression than V T = 6 mL/kg. Multiple linear regression analyses indicated that V T was able to predict changes in IL-6 and CC16, whereas ΔP, L predicted pHa, oxygenation, amphiregulin, and syndecan-1 expression. In the model of ARDS used herein, even at low mechanical power, high V T resulted in VILI. V T control seems to be more important than RR control to mitigate VILI.

The effect of reactive emotions expressed in response to another's anger on inferences of social power.

PubMed

Hareli, Shlomo; David, Shlomo

2017-06-01

Social perception of emotions is influenced by the context in which it occurs. One such context is a social interaction involving an exchange of emotions. The way parties to the interaction are perceived is shaped by the combination of emotions exchanged. This idea was examined by assessing the extent to which expressions of anger toward a target-which, in isolation, are perceived as signals of high social power-are influenced by the target's emotional reaction to it (i.e., reactive emotions). Three studies show that the angry person was perceived as having a higher level of social power when this anger was responded by fear or sadness than when it was responded by neutrality or anger. Study 1 indicated that reactive emotions have a stronger effect on perceived social power when emotions were incongruent with gender stereotypes. Study 2 indicated that these effects are a result of these emotions serving as reactive emotions rather than a benchmark against which the angry person's power is assessed. Study 3 showed that reactive emotions affect perceived social power by serving as signals of the level to which the high social power suggested by the first person's expression is confirmed by its target. Comparing effects of reactive emotions to anger with reactive emotions to sadness, showed that perceived social power of the expresser is determined by the nature of the expression, with some adjustment caused by the reactive emotions. This underscores the importance of social interaction as a context for the social perception of emotions. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Strength-Power Performance of Visually Impaired Paralympic and Olympic Judo Athletes From the Brazilian National Team: A Comparative Study.

PubMed

Loturco, Irineu; Nakamura, Fábio Y; Winckler, Ciro; Bragança, Jaime R; da Fonseca, Roger A; Moraes-Filho, Josué; Zaccani, Wagner A; Kobal, Ronaldo; Cal Abad, Cesar C; Kitamura, Katia; Pereira, Lucas A; Franchini, Emerson

2017-03-01

Loturco, I, Nakamura, FY, Winckler, C, Bragança, JR, da Fonseca, RA, Filho, JM, Zaccani, WA, Kobal, R, Cal Abad, CC, Kitamura, K, Pereira, LA, and Franchini, E. Strength-power performance of visually impaired paralympic and olympic judo athletes from the brazilian national team: a comparative study. J Strength Cond Res 31(3): 743-749, 2017-The aim of this study was to compare the muscle power and maximal isometric strength capacities of Olympic and visually impaired Paralympic judo athletes. Twenty-eight elite judo athletes (7 men and 7 women per group) from the permanent Brazilian National Paralympic and Olympic teams took part in this study. After a specific warm-up, the athletes performed loaded jump squat (JS), bench press (BP), and standing barbell row (SBR) exercises to determine their values of maximum mean propulsive power (MPP) in these respective exercises. The maximal isometric strength (MIS) was also determined for both upper and lower limbs, through the use of BP and half-squat (HS) exercises. Finally, the jumping ability was assessed using unloaded squat jump (SJ). The magnitude-based inference was used to compare the groups. The Olympic judo athletes presented a likely higher SJ height than the Paralympic athletes. The Olympic group presented almost certainly higher MPP in the loaded JS and in the SBR exercises and likely higher MPP in the BP exercise. Importantly, in the MIS assessments the differences between groups in the HS and BP exercises were rated as unclear. In conclusion, our results showed that both Olympic and Paralympic judo athletes present similar levels of maximal isometric strength, but muscle power performance is superior in Olympic athletes.

Cervical inflammation and immunity associated with hormonal contraception, pregnancy, and HIV-1 seroconversion.

PubMed

Morrison, Charles; Fichorova, Raina N; Mauck, Chris; Chen, Pai-Lien; Kwok, Cynthia; Chipato, Tsungai; Salata, Robert; Doncel, Gustavo F

2014-06-01

Hormonal contraception (HC), younger age, and pregnancy have been associated with increased HIV risk in some studies. We sought to elucidate the biological mechanisms for these associations. Case-control selection of specimens from a large, prospective, clinical study. We enrolled and followed 4531 HIV-negative women from Uganda and Zimbabwe using either the injectable depo-medroxyprogesterone acetate (DMPA), combined oral contraception, or no HC (NH). Innate immunity mediators were measured in cervical samples collected from women at their visit before HIV seroconversion (n = 199) and matched visits from women remaining HIV uninfected (n = 633). Generalized linear models were applied after Box-Cox power transformation. Higher RANTES and lower secretory leukocyte protease inhibitor (SLPI) levels were associated with HIV seroconversion. DMPA users had higher RANTES and lower BD-2 levels. Most inflammation-promoting and/or inflammation-inducible mediators were higher [interleukin (IL)-1β, IL-6, IL-8, MIP-3α, vascular endothelial growth factor, and SLPI], and the protective BD-2 and IL-1RA:IL-1β ratio were lower among combined oral contraception users. Pregnant women showed a similar cervical immunity status (higher IL-1β, IL-6, IL-8, vascular endothelial growth factor, SLPI, and IL-1RA; lower IL-1RA:IL-1β). Age <25 years was associated with lower SLPI, IL-8, MIP-3α but higher IL-1RA:IL-1β. Zimbabwean women (with higher HIV seroconversion rates) had overall higher pro-inflammatory and lower anti-inflammatory protein levels than Ugandan women. HC use, pregnancy, and young age alter cervical immunity in different ways known to increase risk of HIV, for example, through increased levels of pro-inflammatory cytokines or decreased levels of SLPI. Higher levels of RANTES may be one factor underlying a possible association between DMPA use and risk of HIV acquisition.

940nm QCW diode laser bars with 70% efficiency at 1 kW output power at 203K: analysis of remaining limits and path to higher efficiency and power at 200K and 300K

NASA Astrophysics Data System (ADS)

Frevert, C.; Bugge, F.; Knigge, S.; Ginolas, A.; Erbert, G.; Crump, P.

2016-03-01

Both high-energy-class laser facilities and commercial high-energy pulsed laser sources require reliable optical pumps with the highest pulse power and electro-optical efficiency. Although commercial quasi-continuous wave (QCW) diode laser bars reach output powers of 300…500 W further improvements are urgently sought to lower the cost per Watt, improve system performance and reduce overall system complexity. Diode laser bars operating at temperatures of around 200 K show significant advances in performance, and are particularly attractive in systems that use cryogenically cooled solid state lasers. We present the latest results on 940 nm, passively cooled, 4 mm long QCW diode bars which operate under pulse conditions of 1.2 ms, 10 Hz at an output power of 1 kW with efficiency of 70% at 203 K: a two-fold increase in power compared to 300 K, without compromising efficiency. We discuss how custom low-temperature design of the vertical layers can mitigate the limiting factors such as series resistance while sustaining high power levels. We then focus on the remaining obstacles to higher efficiency and power, and use a detailed study of multiple vertical structures to demonstrate that the properties of the active region are a major performance limit. Specifically, one key limit to series resistance is transport in the layers around the active region and the differential internal efficiency is closely correlated to the threshold current. Tailoring the barriers around the active region and reducing transparency current density thus promise bars with increased performance at temperatures of 200 K as well as 300 K.

The influence of spatial resolution and smoothing on the detectability of resting-state and task fMRI.

PubMed

Molloy, Erin K; Meyerand, Mary E; Birn, Rasmus M

2014-02-01

Functional MRI blood oxygen level-dependent (BOLD) signal changes can be subtle, motivating the use of imaging parameters and processing strategies that maximize the temporal signal-to-noise ratio (tSNR) and thus the detection power of neuronal activity-induced fluctuations. Previous studies have shown that acquiring data at higher spatial resolutions results in greater percent BOLD signal changes, and furthermore that spatially smoothing higher resolution fMRI data improves tSNR beyond that of data originally acquired at a lower resolution. However, higher resolution images come at the cost of increased acquisition time, and the number of image volumes also influences detectability. The goal of our study is to determine how the detection power of neuronally induced BOLD fluctuations acquired at higher spatial resolutions and then spatially smoothed compares to data acquired at the lower resolutions with the same imaging duration. The number of time points acquired during a given amount of imaging time is a practical consideration given the limited ability of certain populations to lie still in the MRI scanner. We compare acquisitions at three different in-plane spatial resolutions (3.50×3.50mm(2), 2.33×2.33mm(2), 1.75×1.75mm(2)) in terms of their tSNR, contrast-to-noise ratio, and the power to detect both task-related activation and resting-state functional connectivity. The impact of SENSE acceleration, which speeds up acquisition time increasing the number of images collected, is also evaluated. Our results show that after spatially smoothing the data to the same intrinsic resolution, lower resolution acquisitions have a slightly higher detection power of task-activation in some, but not all, brain areas. There were no significant differences in functional connectivity as a function of resolution after smoothing. Similarly, the reduced tSNR of fMRI data acquired with a SENSE factor of 2 is offset by the greater number of images acquired, resulting in few significant differences in detection power of either functional activation or connectivity after spatial smoothing. © 2013.

PEP as a synchrotron radiation source (invited)

NASA Astrophysics Data System (ADS)

Bienenstock, A.; Brown, G.; Wiedemann, H.; Winick, H.

1989-07-01

The 16-GeV storage ring PEP has characteristics which enable it to operate in modes with very low emittance and to accommodate very long undulators, producing synchrotron radiation at x-ray wavelengths with extremely high brightness and coherent power. Two beamlines, each illuminated by a 2-m long, 77-mm period undulator magnet, are now operational and others are planned. In parasitic operation during colliding-beam runs at 14.5 GeV, these beamlines provide photons above 10 keV with a peak brightness of about 1016 photons/(s mm2 mrad2 ) within a 0.1% bandwidth. In low-emittance tests at 7.1 GeV, horizontal emittances of about 5 nm rad were measured, which is about the same as that planned for the new third-generation x-ray sources. With a current of 15 mA at 7.1 GeV, the present undulators deliver photon beams from 2.7 to 14 keV with a peak brightness of about 1017 . Higher performance levels are expected with the implementation of longer undulators and shorter period undulators. In the longer term, because of its large circumference and long straight sections, PEP could be further developed to achieve even higher performance levels with an emittance below 1 nm rad, very long undulators and picosecond bunches, resulting in one to two orders of magnitude higher brightness and coherent power.

IGF-I receptor 275124A>C (rs1464430) polymorphism and athletic performance.

PubMed

Ben-Zaken, Sigal; Meckel, Yoav; Nemet, Dan; Eliakim, Alon

2015-05-01

To examine the prevalence of the Insulin-Like Growth Factor-I receptor (IGF-IR) 275124A>C polymorphism, known to be associated with exercise-related cardiac hypertrophy, among elite endurance and power athletes. One hundred and fifty-nine athletes (118 men and 41 women, age: 35.9±12.2 yrs) participated in the study. We hypothesized that presence of the A allele will be significantly more common among endurance athletes (n=77) compared to power athletes (n=82) and non-physically active controls (n=68). Athletes within each group were further divided according to their individual best performance into elite athletes (those who had represented the country in international track-and-field or triathlon competitions or in the Olympic Games) and national-level athletes. The prevalence of the AA genotype was significantly higher (p<0.05) in the endurance athletes group (49%) compared to the power athletes group (33%), but did not differ from the control group (46%). There was no significant difference in the prevalence of the AA genotype between elite and national level endurance athletes (44% versus 52%, respectively). In contrast, among power athletes, the prevalence of the AA genotype was significantly lower in the elite compared to national level athletes (17% versus 42%, respectively; p<0.05). The results of the present study may suggest that the IGF-IR AA polymorphism is beneficial for endurance-type sports, but is not associated with elite endurance performance. In contrast, the presence of the AA genotype may be a disadvantage in power sports. All together the results of the present study suggest that IGF-IR polymorphism may differentiate between the two edges of the endurance-power athletic performance spectrum. Copyright © 2014 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

[Monitoring the thermal plume from coastal nuclear power plant using satellite remote sensing data: modeling, and validation].

PubMed

Zhu, Li; Zhao, Li-Min; Wang, Qiao; Zhang, Ai-Ling; Wu, Chuan-Qing; Li, Jia-Guo; Shi, Ji-Xiang

2014-11-01

Thermal plume from coastal nuclear power plant is a small-scale human activity, mornitoring of which requires high-frequency and high-spatial remote sensing data. The infrared scanner (IRS), on board of HJ-1B, has an infrared channel IRS4 with 300 m and 4-days as its spatial and temporal resolution. Remote sensing data aquired using IRS4 is an available source for mornitoring thermal plume. Retrieval pattern for coastal sea surface temperature (SST) was built to monitor the thermal plume from nuclear power plant. The research area is located near Guangdong Daya Bay Nuclear Power Station (GNPS), where synchronized validations were also implemented. The National Centers for Environmental Prediction (NCEP) data was interpolated spatially and temporally. The interpolated data as well as surface weather conditions were subsequently employed into radiative transfer model for the atmospheric correction of IRS4 thermal image. A look-up-table (LUT) was built for the inversion between IRS4 channel radiance and radiometric temperature, and a fitted function was also built from the LUT data for the same purpose. The SST was finally retrieved based on those preprocessing procedures mentioned above. The bulk temperature (BT) of 84 samples distributed near GNPS was shipboard collected synchronically using salinity-temperature-deepness (CTD) instruments. The discrete sample data was surface interpolated and compared with the satellite retrieved SST. Results show that the average BT over the study area is 0.47 degrees C higher than the retrieved skin temperature (ST). For areas far away from outfall, the ST is higher than BT, with differences less than 1.0 degrees C. The main driving force for temperature variations in these regions is solar radiation. For areas near outfall, on the contrary, the retrieved ST is lower than BT, and greater differences between the two (meaning > 1.0 degrees C) happen when it gets closer to the outfall. Unlike the former case, the convective heat transfer resulting from the thermal plume is the primary reason leading to the temperature variations. Temperature rising (TR) distributions obtained from remote sensing data and in-situ measurements are consistent, except that the interpolated BT shows more level details (> 5 levels) than that of the ST (up to 4 levels). The areas with higher TR levels (> 2) are larger on BT maps, while for lower TR levels (≤ 2), the two methods perform with no obvious differences. Minimal errors for satellite-derived SST occur regularly around local time 10 a. m. This makes the remote sensing results to be substitutes for in-situ measurements. Therefore, for operational applications of HJ-1B IRS4, remote sensing technique can be a practical approach to monitoring the nuclear plant thermal pollution around this time period.

Applied-field MPD thruster geometry effects

NASA Technical Reports Server (NTRS)

Myers, Roger M.

1991-01-01

Eight MPD thruster configurations were used to study the effects of applied field strength, propellant, and facility pressure on thruster performance. Vacuum facility background pressures higher than approx. 0.12 Pa were found to greatly influence thruster performance and electrode power deposition. Thrust efficiency and specific impulse increased monotonically with increasing applied field strength. Both cathode and anode radii fundamentally influenced the efficiency specific impulse relationship, while their lengths influence only the magnitude of the applied magnetic field required to reach a given performance level. At a given specific impulse, large electrode radii result in lower efficiencies for the operating conditions studied. For all test conditions, anode power deposition was the largest efficiency loss, and represented between 50 and 80 pct. of the input power. The fraction of the input power deposited into the anode decreased with increasing applied field and anode radii. The highest performance measured, 20 pct. efficiency at 3700 seconds specific impulse, was obtained using hydrogen propellant.

Free-beam soliton self-compression in air

NASA Astrophysics Data System (ADS)

Voronin, A. A.; Mitrofanov, A. V.; Sidorov-Biryukov, D. A.; Fedotov, A. B.; Pugžlys, A.; Panchenko, V. Ya; Shumakova, V.; Ališauskas, S.; Baltuška, A.; Zheltikov, A. M.

2018-02-01

We identify a physical scenario whereby soliton transients generated in freely propagating laser beams within the regions of anomalous dispersion in air can be compressed as a part of their free-beam spatiotemporal evolution to yield few-cycle mid- and long-wavelength-infrared field waveforms, whose peak power is substantially higher than the peak power of the input pulses. We show that this free-beam soliton self-compression scenario does not require ionization or laser-induced filamentation, enabling high-throughput self-compression of mid- and long-wavelength-infrared laser pulses within a broad range of peak powers from tens of gigawatts up to the terawatt level. We also demonstrate that this method of pulse compression can be extended to long-range propagation, providing self-compression of high-peak-power laser pulses in atmospheric air within propagation ranges as long as hundreds of meters, suggesting new ways towards longer-range standoff detection and remote sensing.

The very low frequency power spectrum of Centaurus X-3

NASA Technical Reports Server (NTRS)

Gruber, D. E.

1988-01-01

The long-term variability of Cen X-3 on time scales ranging from days to years has been examined by combining data obtained by the HEAO 1 A-4 instrument with data from Vela 5B. A simple interpretation of the data is made in terms of the standard alpha-disk model of accretion disk structure and dynamics. Assuming that the low-frequency variance represents the inherent variability of the mass transfer from the companion, the decline in power at higher frequencies results from the leveling of radial structure in the accretion disk through viscous mixing. The shape of the observed power spectrum is shown to be in excellent agreement with a calculation based on a simplified form of this model. The observed low-frequency power spectrum of Cen X-3 is consistent with a disk in which viscous mixing occurs about as rapidly as possible and on the largest scale possible.

Thermal dephasing in second-harmonic generation of an amplified copper-vapor laser beam in beta barium borate.

PubMed

Prakash, Om; Dixit, Sudhir Kumar; Bhatnagar, Rajiva

2005-03-20

The conversion efficiency in second-harmonic generation of an amplified beam in a master-oscillator power amplifier copper-vapor laser (CVL) is lower than that of the oscillator beam alone. This lower efficiency is often vaguely attributed to wave-front degradation in the amplifier. We investigate the role of wave-front degradation and thermal dephasing in the second-harmonic generation of a CVL from a beta-barium borate crystal. Choosing two beams with constant intrapulse divergence, one from a generalized diffraction filtered resonator master oscillator alone and other obtained by amplifying oscillator by use of a power amplifier, we show that at low flux levels the decrease in efficiency is due to wave-front degradation. At a fundamental power above the critical power for thermal dephasing, the decrease is due to increased UV absorption and consequent thermal dephasing. Thermal dephasing is higher for the beam with the lower coherence width.

Aerobic power and field test results of amateur 15-a-side rugby union players.

PubMed

Sant'anna, Ricardo T; de Souza Castro, Flávio A

2017-12-01

The aim of the present study was to verify whether it is possible to predict aerobic power in amateur 15-a-side rugby union players through the Yo-Yo Intermittent Recovery Test Level 1 (Yo-Yo IRT1) and the 5-meter Multiple Shuttle Test (5-m MST). Forty-two amateur players - 22 forwards and 20 backs - were evaluated in three phases: 1) maximum treadmill test in the laboratory; 2) field test set by a drawing in the first phase; and 3) second field test. Descriptive, comparison, correlation, regression and level of agreement analyses were performed. Backs, when compared to forwards, showed a higher VO2max (61.7±15 mL/kg/min and 51.6±10.1 mL/kg/min, respectively), Yo-Yo IRT1 final level (16.4±0.8 and 14.9±0.9, respectively) and Yo-Yo IRT1 total distance (1283.3±312.5 m and 792±277.6 m, respectively), and a higher final distance in the 5-m MST (686.8±36.6 and 642.9±46.5, respectively). Significant correlations were found between the result and the total distance on the Yo-Yo IRT1 and the VO2max (r=0.425 and r=0.459, respectively). Using the total distance covered in the Yo-Yo IRT1, the VO2max of amateur 15-a-side rugby union players can be estimated through the equation VO2max = 0.016 × (DIST Yo‑Yo) + 40.578. Yo-Yo IRT1 is most useful when the objective is to evaluate the aerobic power of amateur RU players in comparison with the 5-m MST.

Effect of long term high altitude exposure on cardiovascular autonomic adjustment during rest and post-exercise recovery.

PubMed

Bhattarai, Prem; Paudel, Bishnu H; Thakur, Dilip; Bhattarai, Balkrishna; Subedi, Bijay; Khadka, Rita

2018-01-01

Despite the successful adaptation to high altitude, some differences do occur due to long term exposure to the hypoxic environment. The effect of long term high altitude exposure on cardiac autonomic adjustment during basal and post-exercise recovery is less known. Thus we aimed to study the differences in basal cardiac autonomic adjustment and its response to exercise in highlanders and to compare it with lowlanders. The study was conducted on 29 healthy highlander males who were born and brought up at altitude of 3000 m and above from the sea level, their cardiac autonomic adjustment was compared with age, sex, physical activity and ethnicity-matched 29 healthy lowlanders using Heart Rate Variability (HRV) during rest and recovery from sub-maximal exercise (3 m step test). Intergroup comparison between the highlanders and lowlanders and intragroup comparison between the rest and the postexercise recovery conditions were done. Resting heart rate and HRV during rest was comparable between the groups. However, heart rate recovery after 3 min step test was faster in highlanders ( p  < 0.05) along with significantly higher LF power and total power during the recovery phase. Intragroup comparison of highlanders showed higher SDNN ( p  < 0.05) and lower LF/HF ratio ( p  < 0.05) during recovery phase compared to rest which was not significantly different in two phases in lowlanders. Further highlander showed complete recovery of RMSSD, NN50, pNN50 and HF power back to resting level within five minutes, whereas, these parameters failed to return back to resting level in lowlanders within the same time frame. Highlanders completely recovered back to their resting state within five minutes from cessation of step test with parasympathetic reactivation; however, recovery in lowlanders was delayed.

Effects of 946-nm thermal shift and broadening on Nd3+:YAG laser performance

NASA Astrophysics Data System (ADS)

Seyed Ebrahim, Pourmand; Ghasem, Rezaei

2015-12-01

Spectroscopic properties of flashlamp pumped Nd3+:YAG laser are studied as a function of temperature in a range from -30 °C to 60 °C. The spectral width and shift of quasi three-level 946.0-nm inter-Stark emission within the respective intermanifold transitions of 4F3/2 → 4I9/2 are investigated. The 946.0-nm line shifts toward the shorter wavelength and broadens. In addition, the threshold power and slope efficiency of the 946.0-nm laser line are quantified with temperature. The lower the temperature, the lower the threshold power is and the higher the slope efficiency of the 946.0-nm laser line is, thus the higher the laser output is. This phenomenon is attributed to the ion-phonon interaction and the thermal population in the ground state. Project supported by Estahban Branch, Islamic Azad University.

[The pathomorphological characteristics of duodenal peptic ulcer in the victims of the accident at the Chernobyl Atomic Electric Power Station: changes in the gastric mucosa].

PubMed

Degtiareva, L V; Moroz, G Z

1998-01-01

Gastrobiopsies were studied from patients with duodenal ulcer, 62 of whom took part in the elimination of the effects of the Chernobyl Nuclear Power Plant breakdown, 33 were permanent residents in the territories affected by radioactive contamination, and 36 formed the control group. Several distinguishing features were noted in chronic Helicobacter gastritis in victims of Chernobyl accident versus control, such as higher degree and activity of the inflammatory process spreading over large tissue areas, with Helicobacter pylori being recordable in the gastric mucosa in highly increased numbers, and more frequent occurrence of atrophic changes. Incorporation of radionuclides and external irradiation at dose levels exceeding 25 cause most significant disturbances in regeneration of epithelium, with its enterolyzation and dysplasia going on, which fact makes the risk of neoplastic transformations higher.

Heart rate variabilty changes during first week of acclimatization to 3500 m altitude in Indian military personnel.

PubMed

Bhaumik, G; Dass, D; Bhattacharyya, D; Sharma, Y K; Singh, S B

2013-01-01

Acute exposure to hypobaric hypoxia induces the changes in autonomic control of heart rate. Due to emergencies or war like conditions, rapid deployment of Indian military personnel into high altitude frequently occurs. Rapid deployment to high altitude soldiers are at risk of developing high altitude sickness. The present study was conducted to evaluate the acute exposure to high altitude hypobaric hypoxia (3500 m altitude) on the autonomic nervous control of heart rate in Indian military personnel during first week of acclimatization Indices of heart rate variability (viz; R-R interval, total power, low frequency, high frequency, ratio of low to high frequency) and pulse arterial oxygen saturation were measured at sea level and 3500m altitude. Power spectrum of heart rate variability was quantified by low frequency (LF: 0.04-0.15 Hz) and high frequency (HF: 0.15-0.5 Hz) widths. The ratio of LF to HF was also assessed as an index of the sympathovagal balance. Mean R-R interval decreased significantly on day 2 on induction to altitude which tended to increase on day 5. Total power (TP) decreased high altitude and tended to recover within a week. Both HF and LF power showed decrement at 3500m in comparison to sea level. The ratio of LF to HF (LF/HF) at 3500m was significantly higher at 3500m. SpO2 values decreased significantly (P < 0.05) at high altitude on day-2 which increased on day-5. We conclude that autonomic control of the heart rate measured by heart rate variability was altered on acute induction to 3500m which showed a significant decrease in parasympathetic tone and increase in sympathetic tone, then acclimatization seems to be characterized by progressive shift toward a higher parasympathetic tone.

Laser diode and pumped Cr:Yag passively Q-switched yellow-green laser at 543 nm

NASA Astrophysics Data System (ADS)

Yao, Y.; Ling, Zhao; Li, B.; Qu, D. P.; Zhou, K.; Zhang, Y. B.; Zhao, Y.; Zheng, Q.

2013-03-01

Efficient and compact yellow green pulsed laser output at 543 nm is generated by frequency doubling of a passively Q-switched end diode-pumped Nd:YVO4 laser at 1086 nm under the condition of sup-pressing the higher gain transition near 1064 nm. With 15 W of diode pump power and the frequency doubling crystal LBO, as high as 1.58 W output power at 543 nm is achieved. The optical to optical conversion efficiency from the corresponding Q-switched fundamental output to the yellow green output is 49%. The peak power of the Q-switched yellow green pulse laser is up to 30 kW with 5 ns pulse duration. The output power stability over 8 hours is better than 2.56% at the maximum output power. To the best of our knowledge, this is the highest watt-level laser at 543 nm generated by frequency doubling of a passively Q-switched end diode pumped Nd:YVO4 laser at 1086 nm.

Chance-Constrained AC Optimal Power Flow: Reformulations and Efficient Algorithms

DOE PAGES

Roald, Line Alnaes; Andersson, Goran

2017-08-29

Higher levels of renewable electricity generation increase uncertainty in power system operation. To ensure secure system operation, new tools that account for this uncertainty are required. Here, in this paper, we adopt a chance-constrained AC optimal power flow formulation, which guarantees that generation, power flows and voltages remain within their bounds with a pre-defined probability. We then discuss different chance-constraint reformulations and solution approaches for the problem. Additionally, we first discuss an analytical reformulation based on partial linearization, which enables us to obtain a tractable representation of the optimization problem. We then provide an efficient algorithm based on an iterativemore » solution scheme which alternates between solving a deterministic AC OPF problem and assessing the impact of uncertainty. This more flexible computational framework enables not only scalable implementations, but also alternative chance-constraint reformulations. In particular, we suggest two sample based reformulations that do not require any approximation or relaxation of the AC power flow equations.« less

High Performance Power Module for Hall Effect Thrusters

NASA Technical Reports Server (NTRS)

Pinero, Luis R.; Peterson, Peter Y.; Bowers, Glen E.

2002-01-01

Previous efforts to develop power electronics for Hall thruster systems have targeted the 1 to 5 kW power range and an output voltage of approximately 300 V. New Hall thrusters are being developed for higher power, higher specific impulse, and multi-mode operation. These thrusters require up to 50 kW of power and a discharge voltage in excess of 600 V. Modular power supplies can process more power with higher efficiency at the expense of complexity. A 1 kW discharge power module was designed, built and integrated with a Hall thruster. The breadboard module has a power conversion efficiency in excess of 96 percent and weighs only 0.765 kg. This module will be used to develop a kW, multi-kW, and high voltage power processors.

The influence of spatially and temporally high-resolution wind forcing on the power input to near-inertial waves in the ocean

NASA Astrophysics Data System (ADS)

Rimac, Antonija; von Storch, Jin-Song; Eden, Carsten

2013-04-01

The estimated power required to sustain global general circulation in the ocean is about 2 TW. This power is supplied with wind stress and tides. Energy spectrum shows pronounced maxima at near-inertial frequency. Near-inertial waves excited by high-frequency winds represent an important source for deep ocean mixing since they can propagate into the deep ocean and dissipate far away from the generation sites. The energy input by winds to near-inertial waves has been studied mostly using slab ocean models and wind stress forcing with coarse temporal resolution (e.g. 6-hourly). Slab ocean models lack the ability to reproduce fundamental aspects of kinetic energy balance and systematically overestimate the wind work. Also, slab ocean models do not account the energy used for the mixed layer deepening or the energy radiating downward into the deep ocean. Coarse temporal resolution of the wind forcing strongly underestimates the near-inertial energy. To overcome this difficulty we use an eddy permitting ocean model with high-frequency wind forcing. We establish the following model setup: We use the Max Planck Institute Ocean Model (MPIOM) on a tripolar grid with 45 km horizontal resolution and 40 vertical levels. We run the model with wind forcings that vary in horizontal and temporal resolution. We use high-resolution (1-hourly with 35 km horizontal resolution) and low-resolution winds (6-hourly with 250 km horizontal resolution). We address the following questions: Is the kinetic energy of near-inertial waves enhanced when high-resolution wind forcings are used? If so, is this due to higher level of overall wind variability or higher spatial or temporal resolution of wind forcing? How large is the power of near-inertial waves generated by winds? Our results show that near-inertial waves are enhanced and the near-inertial kinetic energy is two times higher (in the storm track regions 3.5 times higher) when high-resolution winds are used. Filtering high-resolution winds in space and time, the near-inertial kinetic energy reduces. The reduction is faster when a temporal filter is used suggesting that the high-frequency wind forcing is more efficient in generating near-inertial wave energy than the small-scale wind forcing. Using low-resolution wind forcing the wind generated power to near-inertial waves is 0.55 TW. When we use high-resolution wind forcing the result is 1.6 TW meaning that the result increases by 300%.

Investigations of initial airtightness after non-anatomic resection of lung parenchyma using a thulium-doped laser with different optical fibres.

PubMed

Kirschbaum, Andreas; Höchsmann, N; Steinfeldt, T; Seyfer, P; Pehl, A; Bartsch, D K; Palade, E

2016-08-01

Lung metastases in healthy patients should be removed non-anatomically whenever possible. This can be done with a laser. Lung parenchyma can be cut very well, because of its high energy absorption at a wavelength of 1940 nm. A coagulation layer is created on the resected surface. It is not clear, whether this surface also needs to be sutured to ensure that it remains airtight even at higher ventilation pressures. It would be helpful, if suturing could be avoided, because the lung can become too puckered, especially with multiple resections, resulting in considerable restriction. We carried out our experiments on isolated and ventilated paracardiac lung lobes of pigs. Non-anatomic resection was carried out reproducibly using three different thulium laser fibres (230, 365 and 600 μm) at two different laser power levels (10 W, 30 W) and three different resection depths (0.5, 1.0 and 2.0 cm). Initial airtightness was investigated while ventilating at normal frequency. We also investigated the bursting pressures of the resected areas by increasing the inspiratory pressure. When 230- and 365-μm fibres were used with a power of 10 W, 70 % of samples were initially airtight up to a resection depth of 1 cm. This rate fell at depths of up to 2 cm. All resected surfaces remained airtight during ventilation when 600-μm fibres were used at both laser power levels (10 and 30 W). The bursting pressures achieved with 600-μm fibres were higher than with the other fibres used: 0.5 cm, 41.6 ± 3.2 mbar; 1 cm, 38.2 ± 2.5 mbar; 2 cm, 33.7 ± 4.8 mbar. As laser power and thickness of laser fibre increased, so the coagulation zone became thicker. With a 600-μm fibre, it measured 145.0 ± 8.2 μm with 10 W power and 315.5 ± 6.4 μm with 30 W power. Closure with sutures after non-anatomic resection of lung parenchyma is not necessary when a thulium laser is used provided a 600-μm fibre and adequate laser power (30 W) are employed. At deeper resection levels, the risk of cutting small segmental bronchi is considerably increased. They must always be closed with sutures.

76 FR 30110 - Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-24

... communication signals used by low frequency mysticetes when they occur near the noise band and thus reduce the communication space of animals (e.g., Clark et al. 2009) and cause increased stress levels (e.g., Foote et al... well as additional lower-powered and higher frequency survey equipment for collecting bathymetric and...

76 FR 58473 - Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-21

... communication signals used by low frequency mysticetes when they occur near the noise band and thus reduce the communication space of animals (e.g., Clark et al. 2009) and cause increased stress levels (e.g., Foote et al... additional lower-powered and higher frequency survey equipment for collecting bathymetric and shallow sub...

Competency-Based Education: Changing the Traditional College Degree Power, Policy, and Practice

ERIC Educational Resources Information Center

Ordonez, Bonnie

2014-01-01

Higher education is going through a time of change. The United States federal government and its Department of Education are calling for reform as student debt has increased and the cost of college tuition has risen steadily to unattainable levels. In the next decade, the number of jobs requiring a college degree will increase to 70% of all new…

2010 NRL Review: Power, Energy, Synergy

DTIC Science & Technology

2010-01-01

scientific, technical, engineering, and mathematics (STEM) fields. To this end, NRL has brought 399 students on board as employees, tutored another...Employees — Recent Ph.D., Faculty Member, and College Graduate Programs, Professional Appointments, and College and High School Student Programs 278...information with higher-level cognitive reasoning; gesture recognition for shoulder-to- shoulder human-robot interaction; and anticipation and learning on a

Psychoacoustic Tinnitus Loudness and Tinnitus-Related Distress Show Different Associations with Oscillatory Brain Activity

PubMed Central

Balkenhol, Tobias; Wallhäusser-Franke, Elisabeth; Delb, Wolfgang

2013-01-01

Background The phantom auditory perception of subjective tinnitus is associated with aberrant brain activity as evidenced by magneto- and electroencephalographic studies. We tested the hypotheses (1) that psychoacoustically measured tinnitus loudness is related to gamma oscillatory band power, and (2) that tinnitus loudness and tinnitus-related distress are related to distinct brain activity patterns as suggested by the distinction between loudness and distress experienced by tinnitus patients. Furthermore, we explored (3) how hearing impairment, minimum masking level, and (4) psychological comorbidities are related to spontaneous oscillatory brain activity in tinnitus patients. Methods and Findings Resting state oscillatory brain activity recorded electroencephalographically from 46 male tinnitus patients showed a positive correlation between gamma band oscillations and psychoacoustic tinnitus loudness determined with the reconstructed tinnitus sound, but not with the other psychoacoustic loudness measures that were used. Tinnitus-related distress did also correlate with delta band activity, but at electrode positions different from those associated with tinnitus loudness. Furthermore, highly distressed tinnitus patients exhibited a higher level of theta band activity. Moreover, mean hearing loss between 0.125 kHz and 16 kHz was associated with a decrease in gamma activity, whereas minimum masking levels correlated positively with delta band power. In contrast, psychological comorbidities did not express significant correlations with oscillatory brain activity. Conclusion Different clinically relevant tinnitus characteristics show distinctive associations with spontaneous brain oscillatory power. Results support hypothesis (1), but exclusively for the tinnitus loudness derived from matching to the reconstructed tinnitus sound. This suggests to preferably use the reconstructed tinnitus spectrum to determine psychoacoustic tinnitus loudness. Results also support hypothesis (2). Moreover, hearing loss and minimum masking level correlate with oscillatory power in distinctive frequency bands. The lack of an association between psychological comorbidities and oscillatory power may be attributed to the overall low level of mental health problems in the present sample. PMID:23326394

Analysis of violet-excited fluorochromes by flow cytometry using a violet laser diode.

PubMed

Telford, William G; Hawley, Teresa S; Hawley, Robert G

2003-07-01

Low power violet laser diodes (VLDs) have been evaluated as potential replacements for water-cooled argon-ion and krypton-ion ultraviolet and violet lasers for DNA content analysis using the Hoechst dyes and 4,6-diamidino-2-phenylindole (Shapiro HMN, Perlmutter NG: Cytometry 44:133-136, 2001). In this study, we used a VLD to excite a variety of violet-excited fluorescent molecules important in biomedical analysis, including the fluorochromes Cascade Blue and Pacific Blue, the expressible fluorescent protein cyan fluorescent protein (CFP), and the fluorogenic alkaline phosphatase (AP) substrate 2-(5'-chloro-2'-phosphoryloxyphenyl)-6-chloro-4-(3H)-quinazoline (ELF-97; for endogenous AP detection and cell surface labeling with AP-conjugated antibodies). Comparisons were made between VLD excitation and a krypton-ion laser emitting at 407 nm (both at higher power levels and with the beam attenuated at levels approximating the VLD) on the same FACSVantage SE stream-in-air flow cytometer. We evaluated a Power Technology 408-nm VLD (30 mW) equipped with circularization optics (18 mW maximum output, set to 15 mW) and a Coherent I-302C krypton-ion laser emitting at power levels ranging from 15 to 75 mW. Cascade Blue, Pacific Blue, and CFP showed comparable signal-to-noise ratios and levels of sensitivity with VLD excitation versus the krypton-ion laser at high and VLD-matched power outputs. Multicolor fluorescent protein analysis with 488-nm excitation of green fluorescent protein and DsRed and VLD excitation of CFP was therefore feasible and was demonstrated. Similar levels of excitation efficiency between krypton-ion and VLD sources also were observed for ELF-97 detection. These evaluations confirmed that VLDs may be cost- and maintenance-effective replacements for water-cooled gas lasers for applications requiring violet excitation in addition to DNA binding dyes. Published 2003 Wiley-Liss, Inc.

Plasma superoxide dismutase-1 as a surrogate marker of vivax malaria severity.

PubMed

Andrade, Bruno B; Reis-Filho, Antonio; Souza-Neto, Sebastião Martins; Raffaele-Netto, Imbroinise; Camargo, Luis M A; Barral, Aldina; Barral-Netto, Manoel

2010-04-06

Severe outcomes have been described for both Plasmodium falciparum and P. vivax infections. The identification of sensitive and reliable markers of disease severity is fundamental to improving patient care. An intense pro-inflammatory response with oxidative stress and production of reactive oxygen species is present in malaria. Inflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha) and antioxidant agents such as superoxide dismutase-1 (SOD-1) are likely candidate biomarkers for disease severity. Here we tested whether plasma levels of SOD-1 could serve as a biomarker of severe vivax malaria. Plasma samples were obtained from residents of the Brazilian Amazon with a high risk for P. vivax transmission. Malaria diagnosis was made by both microscopy and nested PCR. A total of 219 individuals were enrolled: non-infected volunteers (n = 90) and individuals with vivax malaria: asymptomatic (n = 60), mild (n = 50) and severe infection (n = 19). SOD-1 was directly associated with parasitaemia, plasma creatinine and alanine amino-transaminase levels, while TNF-alpha correlated only with the later enzyme. The predictive power of SOD-1 and TNF-alpha levels was compared. SOD-1 protein levels were more effective at predicting vivax malaria severity than TNF-alpha. For discrimination of mild infection, elevated SOD-1 levels showed greater sensitivity than TNF-alpha (76% vs. 30% respectively; p<0.0001), with higher specificity (100% vs. 97%; p<0.0001). In predicting severe vivax malaria, SOD-1 levels exhibited higher sensitivity than TNF-alpha (80% vs. 56%, respectively; p<0.0001; likelihood ratio: 7.45 vs. 3.14; p<0.0001). Neither SOD-1 nor TNF-alpha could discriminate P. vivax infections from those caused by P. falciparum. SOD-1 is a powerful predictor of disease severity in individuals with different clinical presentations of vivax malaria.

Influence of linearly polarized near-infrared irradiation on deformability of human stored erythrocytes.

PubMed

Yokoyama, Kozo; Sugiyama, Kazuna

2003-02-01

To investigate the influence of linearly polarized near-infrared irradiation using the Super Lizer trade mark on deformability of human erythrocytes. Not only low-powered laser but also linearly polarized near-infrared beams have some biostimulation effects on various tissues. There were some reports of erythrocyte deformability improved by low-powered He-Ne laser irradiation. Human erythrocyte samples stored for three weeks were adjusted to 30% hematocrit. Erythrocyte deformability presented as the filter filtration rate was measured. There was no difference of the filter filtration rate between control group without irradiation and the group of 125 mJ/cm(2) exposure level at a wavelength of 830 nm. However, the groups of 625 and 1,250 mJ/cm(2) exposure levels at a wavelength of 830 nm showed higher filter filtration rates compared to the control group. Linearly polarized near-infrared irradiation in a range of 625-1,250 mJ/cm(2) exposure level at a wavelength of 830 nm improved deformability of human stored erythrocytes.

Infrared Luminescence at 1010 nm and 1500 nm in LiNbO3:Er3+ Excitted by Short Pulse Radiation at 980 nm

NASA Astrophysics Data System (ADS)

Kokanyan, E. P.; Demirkhanyan, G. G.; Steveler, E.; Rinnert, H.; Aillerie, M.

Luminescence of LiNbO3:Er3+ crystal at a wavelength of 1010 nm and 1500 nm under pulsed excitation of different power at a wavelength of 980 nm are experimentally and theoretically studied. It is revealed, that the main part of the absorbed energy gives rise to the luminescence at 1500 nm. Considered concentrations of Er3+ impurity ions allow to exclude cooperative processes in the impurity subsystem. The experimental results are interpreted in the framework of a three electronic levels system, assuming that the population of the higher lasing level 4I13/2 in the crystal under study is caused by relaxation processes from the excited level. It is shown that for obtaining of a laser radiation at about 1500 nm one can effectively use a pulse-pumping at 980 nm with a power density in a range of 50 ÷ 60 MW/cm2.

Relationship between Nutrition Knowledge and Physical Fitness in Semiprofessional Soccer Players

PubMed Central

Nikolaidis, P. T.; Theodoropoulou, E.

2014-01-01

Whereas nutrition has a crucial role on sport performance, it is not clear to what extent nutrition knowledge is associated with physical fitness. The aim of this study was to examine the current level of nutrition knowledge of soccer players and whether this level is associated with physical fitness. Soccer players (n = 185, aged 21.3 ± 4.9 yr, weight 72.3 ± 8.4 kg, and height 177.5 ± 6.4 cm) performed a battery of physical fitness tests (sit-and-reach test, SAR; physical working capacity in heart rate 170, PWC170; and Wingate anaerobic test, WAnT) and completed an 11-item nutrition knowledge questionnaire (NKQ). Low to moderate Pearson correlations (0.15 < r < 0.34, p < 0.05) of NKQ with age, weight, height, fat free mass (FFM), SAR, peak power, and mean power of WAnT were observed. Soccer players with high score in NKQ were older (4.4 yr (2.2; 6.6), mean difference (95% confidence intervals)) and heavier (4.5 kg (0.6; 8.3)) with higher FFM (4.0 kg (1.1; 6.8)) and peak power (59 W (2; 116)) than their counterparts with low score. The moderate score in the NKQ suggests that soccer players should be targeted for nutrition education. Although the association between NKQ and physical fitness was low to moderate, there were indications that better nutrition knowledge might result in higher physical fitness and, consequently, soccer performance. PMID:25140277

Relationship between Nutrition Knowledge and Physical Fitness in Semiprofessional Soccer Players.

PubMed

Nikolaidis, P T; Theodoropoulou, E

2014-01-01

Whereas nutrition has a crucial role on sport performance, it is not clear to what extent nutrition knowledge is associated with physical fitness. The aim of this study was to examine the current level of nutrition knowledge of soccer players and whether this level is associated with physical fitness. Soccer players (n = 185, aged 21.3 ± 4.9 yr, weight 72.3 ± 8.4 kg, and height 177.5 ± 6.4 cm) performed a battery of physical fitness tests (sit-and-reach test, SAR; physical working capacity in heart rate 170, PWC170; and Wingate anaerobic test, WAnT) and completed an 11-item nutrition knowledge questionnaire (NKQ). Low to moderate Pearson correlations (0.15 < r < 0.34, p < 0.05) of NKQ with age, weight, height, fat free mass (FFM), SAR, peak power, and mean power of WAnT were observed. Soccer players with high score in NKQ were older (4.4 yr (2.2; 6.6), mean difference (95% confidence intervals)) and heavier (4.5 kg (0.6; 8.3)) with higher FFM (4.0 kg (1.1; 6.8)) and peak power (59 W (2; 116)) than their counterparts with low score. The moderate score in the NKQ suggests that soccer players should be targeted for nutrition education. Although the association between NKQ and physical fitness was low to moderate, there were indications that better nutrition knowledge might result in higher physical fitness and, consequently, soccer performance.

Neural oscillatory mechanisms during novel grammar learning underlying language analytical abilities.

PubMed

Kepinska, Olga; Pereda, Ernesto; Caspers, Johanneke; Schiller, Niels O

2017-12-01

The goal of the present study was to investigate the initial phases of novel grammar learning on a neural level, concentrating on mechanisms responsible for individual variability between learners. Two groups of participants, one with high and one with average language analytical abilities, performed an Artificial Grammar Learning (AGL) task consisting of learning and test phases. During the task, EEG signals from 32 cap-mounted electrodes were recorded and epochs corresponding to the learning phases were analysed. We investigated spectral power modulations over time, and functional connectivity patterns by means of a bivariate, frequency-specific index of phase synchronization termed Phase Locking Value (PLV). Behavioural data showed learning effects in both groups, with a steeper learning curve and higher ultimate attainment for the highly skilled learners. Moreover, we established that cortical connectivity patterns and profiles of spectral power modulations over time differentiated L2 learners with various levels of language analytical abilities. Over the course of the task, the learning process seemed to be driven by whole-brain functional connectivity between neuronal assemblies achieved by means of communication in the beta band frequency. On a shorter time-scale, increasing proficiency on the AGL task appeared to be supported by stronger local synchronisation within the right hemisphere regions. Finally, we observed that the highly skilled learners might have exerted less mental effort, or reduced attention for the task at hand once the learning was achieved, as evidenced by the higher alpha band power. Copyright © 2017 Elsevier Inc. All rights reserved.

Threshold-dependent sample sizes for selenium assessment with stream fish tissue

USGS Publications Warehouse

Hitt, Nathaniel P.; Smith, David R.

2015-01-01

Natural resource managers are developing assessments of selenium (Se) contamination in freshwater ecosystems based on fish tissue concentrations. We evaluated the effects of sample size (i.e., number of fish per site) on the probability of correctly detecting mean whole-body Se values above a range of potential management thresholds. We modeled Se concentrations as gamma distributions with shape and scale parameters fitting an empirical mean-to-variance relationship in data from southwestern West Virginia, USA (63 collections, 382 individuals). We used parametric bootstrapping techniques to calculate statistical power as the probability of detecting true mean concentrations up to 3 mg Se/kg above management thresholds ranging from 4 to 8 mg Se/kg. Sample sizes required to achieve 80% power varied as a function of management thresholds and Type I error tolerance (α). Higher thresholds required more samples than lower thresholds because populations were more heterogeneous at higher mean Se levels. For instance, to assess a management threshold of 4 mg Se/kg, a sample of eight fish could detect an increase of approximately 1 mg Se/kg with 80% power (given α = 0.05), but this sample size would be unable to detect such an increase from a management threshold of 8 mg Se/kg with more than a coin-flip probability. Increasing α decreased sample size requirements to detect above-threshold mean Se concentrations with 80% power. For instance, at an α-level of 0.05, an 8-fish sample could detect an increase of approximately 2 units above a threshold of 8 mg Se/kg with 80% power, but when α was relaxed to 0.2, this sample size was more sensitive to increasing mean Se concentrations, allowing detection of an increase of approximately 1.2 units with equivalent power. Combining individuals into 2- and 4-fish composite samples for laboratory analysis did not decrease power because the reduced number of laboratory samples was compensated for by increased precision of composites for estimating mean conditions. However, low sample sizes (<5 fish) did not achieve 80% power to detect near-threshold values (i.e., <1 mg Se/kg) under any scenario we evaluated. This analysis can assist the sampling design and interpretation of Se assessments from fish tissue by accounting for natural variation in stream fish populations.

Effect of Voltage Level on Power System Design for Solar Electric Propulsion Missions

NASA Technical Reports Server (NTRS)

Kerslake, Thomas W.

2003-01-01

This paper presents study results quantifying the benefits of higher voltage, electric power system designs for a typical solar electric propulsion spacecraft Earth orbiting mission. A conceptual power system architecture was defined and design points were generated for system voltages of 28-V, 50-V, 120-V, and 300-V using state-of-the-art or advanced technologies. A 300-V 'direct-drive' architecture was also analyzed to assess the benefits of directly powering the electric thruster from the photovoltaic array without up-conversion. Fortran and spreadsheet computational models were exercised to predict the performance and size power system components to meet spacecraft mission requirements. Pertinent space environments, such as electron and proton radiation, were calculated along the spiral trajectory. In addition, a simplified electron current collection model was developed to estimate photovoltaic array losses for the orbital plasma environment and that created by the thruster plume. The secondary benefits of power system mass savings for spacecraft propulsion and attitude control systems were also quantified. Results indicate that considerable spacecraft wet mass savings were achieved by the 300-V and 300-V direct-drive architectures.

A SiC MOSFET Based Inverter for Wireless Power Transfer Applications

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

Onar, Omer C; Chinthavali, Madhu Sudhan; Campbell, Steven L

2014-01-01

In a wireless power transfer (WPT) system, efficiency of the power conversion stages is crucial so that the WPT technology can compete with the conventional conductive charging systems. Since there are 5 or 6 power conversion stages, each stage needs to be as efficient as possible. SiC inverters are crucial in this case; they can handle high frequency operation and they can operate at relatively higher temperatures resulting in reduces cost and size for the cooling components. This study presents the detailed power module design, development, and fabrication of a SiC inverter. The proposed inverter has been tested at threemore » center frequencies that are considered for the WPT standardization. Performance of the inverter at the same target power transfer level is analyzed along with the other system components. In addition, another SiC inverter has been built in authors laboratory by using the ORNL designed and developed SiC modules. It is shown that the inverter with ORNL packaged SiC modules performs simular to that of the inverter having commercially available SiC modules.« less

Theoretical studies of solar-pumped lasers

NASA Technical Reports Server (NTRS)

Harries, W. L.

1983-01-01

Metallic vapor lasers of Na2 and Li2 are examined as solar energy converters. The absorbed photons cause transitions to vibrational-rotational levels in an upper electronic state. With broad band absorption the resultant levels can have quantum numbers considerably higher than the upper lasing level. The excited molecule then relaxes to the upper lasing level which is one of the lower vibrational levels in the upper electronic state. The relaxation occurs from collisions, provided the molecule is not quenched into the ground level electronic state. Lasing occurs with a transition to a vibrational level in the lower electronic state. Rough estimates of solar power efficiencies are 1 percent for Na2 and probably a similar figure for Li2. The nondissociative lasers from a family distinct from materials which dissociate to yield an excited atom.

Isometric quadriceps strength determines sailing performance and neuromuscular fatigue during an upwind sailing emulation.

PubMed

Bourgois, Jan G; Callewaert, Margot; Celie, Bert; De Clercq, Dirk; Boone, Jan

2016-01-01

This study investigates the physiological responses to upwind sailing on a laser emulation ergometer and analyses the components of the physical profile that determine the physiological responses related to sailing level. Ten male high-level laser sailors performed an upwind sailing test, incremental cycling test and quadriceps strength test. During the upwind sailing test, heart rate (HR), oxygen uptake, ventilation, respiratory exchange ratio, rating of perceived exertion (RPE) and lactate concentration were measured, combined with near-infrared spectroscopy (NIRS) and electromyography (EMG) registration of the M. Vastus lateralis. Repeated measures ANOVA showed for the cardio-respiratory, metabolic and muscles responses (mean power frequency [MPF], root mean square [RMS], deoxy[Hb+Mb]) during the upwind sailing test an initial significant increase followed by a stabilisation, despite a constant increase in RPE. Stepwise regression analysis showed that better sailing level was for 46.5% predicted by lower MPF decrease. Lower MPF decrease was for 57.8% predicted by a higher maximal isometric quadriceps strength. In conclusion, this study indicates that higher sailing level was mainly determined by a lower rate of neuromuscular fatigue during the upwind sailing test (as indicated by MPF decrease). Additionally, the level of neuromuscular fatigue was mainly determined by higher maximal isometric quadriceps strength stressing the importance of resistance training in the planning of training.

Top-down causation and emergence: some comments on mechanisms

PubMed Central

Ellis, George F. R.

2012-01-01

Both bottom-up and top-down causation occur in the hierarchy of structure and causation. A key feature is multiple realizability of higher level functions, and consequent existence of equivalence classes of lower level variables that correspond to the same higher level state. Five essentially different classes of top-down influence can be identified, and their existence demonstrated by many real-world examples. They are: algorithmic top-down causation; top-down causation via non-adaptive information control, top-down causation via adaptive selection, top-down causation via adaptive information control and intelligent top-down causation (the effect of the human mind on the physical world). Through the mind, abstract entities such as mathematical structures have causal power. The causal slack enabling top-down action to take place lies in the structuring of the system so as to attain higher level functions; in the way the nature of lower level elements is changed by context, and in micro-indeterminism combined with adaptive selection. Understanding top-down causation can have important effects on society. Two cases will be mentioned: medical/healthcare issues, and education—in particular, teaching reading and writing. In both cases, an ongoing battle between bottom-up and top-down approaches has important consequences for society. PMID:23386967

Electronic Equipment Proposal to Improve the Photovoltaic Systems Efficiency

NASA Astrophysics Data System (ADS)

Flores-Mena, J. E.; Juárez Morán, L. A.; Díaz Reyes, J.

2011-05-01

This paper reports a new technique proposal to improve the photovoltaic systems. It was made to design and implement an electronic system that will detect, capture, and transfer the maximum power of the photovoltaic (PV) panel to optimize the supplied power of a solar panel. The electronic system works on base technical proposal of electrical sweeping of electric characteristics using capacitive impedance. The maximum power is transformed and the solar panel energy is sent to an automotive battery. This electronic system reduces the energy lost originated when the solar radiation level decreases or the PV panel temperature is increased. This electronic system tracks, captures, and stores the PV module's maximum power into a capacitor. After, a higher voltage level step-up circuit was designed to increase the voltage of the PV module's maximum power and then its current can be sent to a battery. The experimental results show that the developed electronic system has 95% efficiency. The measurement was made to 50 W, the electronic system works rightly with solar radiation rate from 100 to 1,000 W m - 2 and the PV panel temperature rate changed from 1 to 75°C. The main advantage of this electronic system compared with conventional methods is the elimination of microprocessors, computers, and sophisticated numerical approximations, and it does not need any small electrical signals to track the maximum power. The proposed method is simple, fast, and it is also cheaper.

Low temperature hot air drying of potato cubes subjected to osmotic dehydration and intermittent microwave: drying kinetics, energy consumption and product quality indexes

NASA Astrophysics Data System (ADS)

Dehghannya, Jalal; Bozorghi, Somayyeh; Heshmati, Maryam Khakbaz

2018-04-01

Hot-air drying is a slow energy-extensive process. Use of intermittent microwave (IM) in hot-air (HA) drying of food products is characterized with advantages including reduced process time, energy saving, and improved final quality. In this study, the effect of IM-HA drying following an osmotic dehydration (OD) pretreatment was analyzed on qualitative and quantitative properties of the output (i.e. effective moisture diffusion coefficient (Deff), shrinkage, bulk density, rehydration and energy consumption). Temperature and airflow velocity were fixed at 40°C and 1 m/s, respectively. The process variables included sucrose solution concentration at five levels (0 or control, 10, 30, 50 and 70 w/w%), microwave output power at four levels (0 or control, 360, 600 and 900 W), and pulse ratio at four levels (1, 2, 3 and 4). Use of osmotic dehydration in combination with IM-HA drying reduced the drying time by up to about 54%. Increasing the osmotic solution concentration to 30% and using higher pulse ratios increased the Deff. The lowest shrinkage and bulk density as well as the highest rehydration belonged to the 900 W microwave power and pulse ratio of 4. The lowest energy consumption was observed when using the 900 W power level, showing 63.27% less consumption than the HA drying method.

Evaluation of WRF-Predicted Near-Hub-Height Winds and Ramp Events over a Pacific Northwest Site with Complex Terrain

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

Yang, Qing; Berg, Larry K.; Pekour, Mikhail

The WRF model version 3.3 is used to simulate near hub-height winds and power ramps utilizing three commonly used planetary boundary-layer (PBL) schemes: Mellor-Yamada-Janjic (MYJ), University of Washington (UW), and Yonsei University (YSU). The predicted winds have small mean biases compared with observations. Power ramps and step changes (changes within an hour) consistently show that the UW scheme performed better in predicting up ramps under stable conditions with higher prediction accuracy and capture rates. Both YSU and UW scheme show good performance predicting up- and down- ramps under unstable conditions with YSU being slightly better for ramp durations longer thanmore » an hour. MYJ is the most successful simulating down-ramps under stable conditions. The high wind speed and large shear associated with low-level jets are frequently associated with power ramps, and the biases in predicted low-level jet explain some of the shown differences in ramp predictions among different PBL schemes. Low-level jets were observed as low as ~200 m in altitude over the Columbia Basin Wind Energy Study (CBWES) site, located in an area of complex terrain. The shear, low-level peak wind speeds, as well as the height of maximum wind speed are not well predicted. Model simulations with 3 PBL schemes show the largest variability among them under stable conditions.« less

Analysis of satellite measurements of terrestrial radio noise

NASA Technical Reports Server (NTRS)

Bakalyar, G.; Caruso, J. A.; Vargas-Vila, R.; Ziemba, E.

1974-01-01

Worldwide distributions of terrestrial radio noise as monitored by Radio Astronomy Explorer 1 (RAE 1) generated and compared with CCIR predictions. These contour maps show the global morphology of radio noise at 6.55 and 9.18 MHz for fall, winter, spring and summer during the local time blocks of 00-08 LT and 16-24 LT. These computer produced maps show general agreement with CCIR predictions over large land masses. The RAE and CCIR maps diverge at high latitudes over Asia and frequently over ocean regions. Higher noise levels observed by RAE at high latitudes are attributed to magnetospheric emission while higher noise levels observed by RAE over Asia are attributable to high power transmitters. Analysis of RAE noise observations in conjunction with various geophysical phenomena showed no obvious correlation.

All-fiber pyroelectric nanogenerator

NASA Astrophysics Data System (ADS)

Ghosh, Sujoy Kumar; Xie, Mengying; Bowen, Christopher Rhys; Mandal, Dipankar

2018-04-01

An all-fiber pyroelectric nanogenerator (PyNG) is fabricated where both the active pyroelectric component and the electrodes were composed of fiber. The pyroelectric component was made with randomly organized electrospun PVDF nano-fibers possessing ferroelectric β- and γ-phases. The PyNG possess higher level of sensitivity which can detect very low level of temperature fluctuation, as, low as, 2 K. In addition, the thermal energy harvesting ability of the PyNG under several temperature variations and cycling frequencies paves the way for next generation thermal sensor and self-powered flexible micro-electronics.

Diode lasers optimized in brightness for fiber laser pumping

NASA Astrophysics Data System (ADS)

Kelemen, M.; Gilly, J.; Friedmann, P.; Hilzensauer, S.; Ogrodowski, L.; Kissel, H.; Biesenbach, J.

2018-02-01

In diode laser applications for fiber laser pumping and fiber-coupled direct diode laser systems high brightness becomes essential in the last years. Fiber coupled modules benefit from continuous improvements of high-power diode lasers on chip level regarding output power, efficiency and beam characteristics resulting in record highbrightness values and increased pump power. To gain high brightness not only output power must be increased, but also near field widths and far field angles have to be below a certain value for higher power levels because brightness is proportional to output power divided by beam quality. While fast axis far fields typically show a current independent behaviour, for broadarea lasers far-fields in the slow axis suffer from a strong current and temperature dependence, limiting the brightness and therefore their use in fibre coupled modules. These limitations can be overcome by carefully optimizing chip temperature, thermal lensing and lateral mode structure by epitaxial and lateral resonator designs and processing. We present our latest results for InGaAs/AlGaAs broad-area single emitters with resonator lengths of 4mm emitting at 976nm and illustrate the improvements in beam quality over the last years. By optimizing the diode laser design a record value of the brightness for broad-area lasers with 4mm resonator length of 126 MW/cm2sr has been demonstrated with a maximum wall-plug efficiency of more than 70%. From these design also pump modules based on 9 mini-bars consisting of 5 emitters each have been realized with 360W pump power.

Microwave Frequency Multiplier

NASA Astrophysics Data System (ADS)

Velazco, J. E.

2017-02-01

High-power microwave radiation is used in the Deep Space Network (DSN) and Goldstone Solar System Radar (GSSR) for uplink communications with spacecraft and for monitoring asteroids and space debris, respectively. Intense X-band (7.1 to 8.6 GHz) microwave signals are produced for these applications via klystron and traveling-wave microwave vacuum tubes. In order to achieve higher data rate communications with spacecraft, the DSN is planning to gradually furnish several of its deep space stations with uplink systems that employ Ka-band (34-GHz) radiation. Also, the next generation of planetary radar, such as Ka-Band Objects Observation and Monitoring (KaBOOM), is considering frequencies in the Ka-band range (34 to 36 GHz) in order to achieve higher target resolution. Current commercial Ka-band sources are limited to power levels that range from hundreds of watts up to a kilowatt and, at the high-power end, tend to suffer from poor reliability. In either case, there is a clear need for stable Ka-band sources that can produce kilowatts of power with high reliability. In this article, we present a new concept for high-power, high-frequency generation (including Ka-band) that we refer to as the microwave frequency multiplier (MFM). The MFM is a two-cavity vacuum tube concept where low-frequency (2 to 8 GHz) power is fed into the input cavity to modulate and accelerate an electron beam. In the second cavity, the modulated electron beam excites and amplifies high-power microwaves at a frequency that is a multiple integer of the input cavity's frequency. Frequency multiplication factors in the 4 to 10 range are being considered for the current application, although higher multiplication factors are feasible. This novel beam-wave interaction allows the MFM to produce high-power, high-frequency radiation with high efficiency. A key feature of the MFM is that it uses significantly larger cavities than its klystron counterparts, thus greatly reducing power density and arcing concerns. We present a theoretical analysis for the beam-wave interactions in the MFM's input and output cavities. We show the conditions required for successful frequency multiplication inside the output cavity. Computer simulations using the plasma physics code MAGIC show that 100 kW of Ka-band (32-GHz) output power can be produced using an 80-kW X-band (8-GHz) signal at the MFM's input. The associated MFM efficiency - from beam power to Ka-band power - is 83 percent. Thus, the overall klystron-MFM efficiency is 42 percent - assuming that a klystron with an efficiency of 50 percent delivers the input signal.

Prestimulus oscillatory activity in the alpha band predicts visual discrimination ability.

PubMed

van Dijk, Hanneke; Schoffelen, Jan-Mathijs; Oostenveld, Robert; Jensen, Ole

2008-02-20

Although the resting and baseline states of the human electroencephalogram and magnetoencephalogram (MEG) are dominated by oscillations in the alpha band (approximately 10 Hz), the functional role of these oscillations remains unclear. In this study we used MEG to investigate how spontaneous oscillations in humans presented before visual stimuli modulate visual perception. Subjects had to report if there was a subtle difference in gray levels between two superimposed presented discs. We then compared the prestimulus brain activity for correctly (hits) versus incorrectly (misses) identified stimuli. We found that visual discrimination ability decreased with an increase in prestimulus alpha power. Given that reaction times did not vary systematically with prestimulus alpha power changes in vigilance are not likely to explain the change in discrimination ability. Source reconstruction using spatial filters allowed us to identify the brain areas accounting for this effect. The dominant sources modulating visual perception were localized around the parieto-occipital sulcus. We suggest that the parieto-occipital alpha power reflects functional inhibition imposed by higher level areas, which serves to modulate the gain of the visual stream.

Particle distributions in approximately 10(13) - 10(16) eV air shower cores at mountain altitude and comparison with Monte Carlo simulations

NASA Technical Reports Server (NTRS)

Ash, A. G.

1985-01-01

Photographs of 521 shower cores in an array of current-limited spark (discharge) chambers at Sacramento Peak (2900m above sea level, 730 g /sq cm.), New Mexico, U.S.A., have been analyzed and the results compared with similar data from Leeds (80m above sea level, 1020 g sq cm.). It was found that the central density differential spectrum is consistent with a power law index of -2 up to approx. 1500/sq m where it steepens, and that shower cores become flatter on average with increasing size. Scaling model predictions for proton primaries with a approx E sup -2.71 energy spectrum account well for the altitude dependence of the data at lower densities. However, deviations at higher densities indicate a change in hadron interaction characteristics between approx few x 10 to the 14th power and 10 to the 15th power eV primary energy causing particles close to the shower axis to be spread further out.

Numerical simulation of the generation of turbulence from cometary ion pick-up

NASA Technical Reports Server (NTRS)

Goldstein, M. L.; Roberts, D. A.; Matthaeus, W. H.

1987-01-01

Observations of magnetic field fluctuations near Comet Halley have revealed a rapid development of a Kolmogoroff-like turbulence spectrum extending from below 0.01 Hz to above 0.1 Hz. Spectra obtained far from the comet have a strong peak in power near the Doppler-shifted ion-cyclotron frequency of singly ionized water. Closer to the comet, the spectrum at higher frequencies is enhanced in power level over the background solar wind spectrum by approximately an order of magnitude. The equations of incompressible MHD are solved using a two-dimensional 256 x 256 mode spectral method code to simulate this spectral evolution as an inertial range turbulent cascade. The initial conditions contained a constant magnetic field and a single coherent wave mode at a low wave number. The solar wind turbulence was modeled by a background noise spectrum having a Kolmogoroff spectral index. The coherent mode decayed into an inertial range spectrum with Kolmogoroff slope within a few eddy-turnover times. Both the time scale and the increase in power level of the turbulence seen in the simulation are in accord with the Giotto observations.

Analytical approach to the multi-state lasing phenomenon in quantum dot lasers

NASA Astrophysics Data System (ADS)

Korenev, V. V.; Savelyev, A. V.; Zhukov, A. E.; Omelchenko, A. V.; Maximov, M. V.

2013-03-01

We introduce an analytical approach to describe the multi-state lasing phenomenon in quantum dot lasers. We show that the key parameter is the hole-to-electron capture rate ratio. If it is lower than a certain critical value, the complete quenching of ground-state lasing takes place at high injection levels. At higher values of the ratio, the model predicts saturation of the ground-state power. This explains the diversity of experimental results and their contradiction to the conventional rate equation model. Recently found enhancement of ground-state lasing in p-doped samples and temperature dependence of the ground-state power are also discussed.

Application programs written by using customizing tools of a computer-aided design system

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

Li, X.; Huang, R.; Juricic, D.

1995-12-31

Customizing tools of Computer-Aided Design Systems have been developed to such a degree as to become equivalent to powerful higher-level programming languages that are especially suitable for graphics applications. Two examples of application programs written by using AutoCAD`s customizing tools are given in some detail to illustrate their power. One tool uses AutoLISP list-processing language to develop an application program that produces four views of a given solid model. The other uses AutoCAD Developmental System, based on program modules written in C, to produce an application program that renders a freehand sketch from a given CAD drawing.

Influence of the Ultrasonic Power Applied on Freeze Drying Kinetics

NASA Astrophysics Data System (ADS)

Brines, C.; Mulet, A.; García-Pérez, J. V.; Riera, E.; Cárcel, J. A.

The atmospheric freeze drying (AFD) constitutes an interesting alternative to vacuum freeze drying providing products with similar quality at lowest cost. However, the long process time needed represent an important drawback. In this sense, the application of high intensity ultrasound can enhance heat and mass transfer and intensify the operation. In hot air drying operation, the ultrasonic effects are dependent on the process variables such as air velocity, internal sample structure or ultrasonic power applied. However, in AFD processes, the internal structure of material or the air velocity has not significant influence on the magnitude of ultrasonic effects. The aim of this work was to determine the influence on drying kinetics of the ultrasonic power applied during the AFD of apple. For that purpose, AFD experiments (-10 °C, 2 m/s and 15% relative humidity) of apple slabs (cv. Granny Smith, 30 x 30 x 10 mm) were carried out with ultrasound application (21 kHz) at different power levels (0, 10.3, 20.5 and 30.8 kW/m3). The drying kinetics was obtained from the initial moisture content and the weight evolution of samples during drying. Experimental results showed a significant (p<0.05) influence of the ultrasound application on drying. Thus, drying time was shorter as higher the ultrasonic power applied. From modeling, it was observed that the effective diffusion coefficient identified was 4.8 times higher when ultrasound was applied at the lowest power tested (10.3 kW/m3) that illustrated the high intensification potential of ultrasound application in the AFD.

Power differentials in bullying: individuals in a community context.

PubMed

Schumann, Lyndall; Craig, Wendy; Rosu, Andrei

2014-03-01

Central to the definition of bullying is the abuse of power. Power relationships are inherent in social groups, by virtue of differing size, strength, age, socioeconomic status (SES), or social connectedness of individuals. Beyond the influence of these individual characteristics, environmental factors have the potential to affect the power dynamic in bullying and victimization, but are a relatively unexplored research area. In particular, we know little about how the community-level factors relate to bullying in the adolescent population. The present study is guided by a social ecological perspective to gain a deeper understanding of the individual and built community characteristics (e.g., parks, recreational spaces, buildings that facilitate social interaction and community connectedness) that contribute to the power dynamics related to victimization or bullying in traditional and electronic contexts. Data were collected from 17,777 students in Grades 6 to 10 as part of the 2009/2010 Health Behavior in School-aged Children (HBSC) Survey, from Geographical Information Systems (GIS) data, and from 2006 Canadian Census data. Two nested models were run using HLM with age, gender, ethnicity, SES, social inclusion factors (e.g., collective efficacy), and community resource factors (e.g., access to recreation) as predictors. Characteristics of individuals that placed them at a power disadvantage (being younger, female, and having low SES) were linked to higher rates of victimization. Lower individual collective efficacy was also associated with higher rates of traditional and electronic victimization. Community recreational opportunities were associated with decreased victimization in both contexts. The relative importance of individual and built environmental factors and conceptualization of bullying interactions within a social ecology model are discussed.

Increased formaldehyde in jet engine exhaust with changes to JP-8, lower temperature, and lower humidity irritates eyes and respiratory tract.

PubMed

Kobayashi, A; Kikukawa, A

2000-04-01

Formaldehyde (FA) in exhaust from F-4 aircraft with low smoke combustor(LSC) J79 engines has been reported to be of sufficient concentration to cause irritation. It has also been noted that eye and respiratory irritation became more frequent and severe after the fuel was changed from JP-4 to JP-8. The present sturdy investigated the effect of jet fuel and power setting on formaldehyde concentrations in the exhaust. We also investigated the exposure to formaldehyde among pilots and flight line personnel. The exhaust from LSC J79 engines using different types of fuel (JP-8 and JP-4) was sampled 50 m behind the engine at different power settings in July (summer season in Japan) and February (winter season ). It was also sampled at 75% power settings using JP-8 in July. At an idle power setting, the FA concentration was higher in the exhaust of engines using JP-8 (1.31 ppm in July and 2.78 ppm in February) than in engines using JP-4 (0.95 ppm in July and 1.84 ppm in February). The FA concentration increased as both ambient temperature and relative humility decreased in the sampling atmosphere. The FA concentration of JP-8 fuel at an idle power setting (65%) was higher than that at a 71.5% power setting (1.32 ppm and 0.86 ppm, respectively). The FA concentrations in LSCJ79 engine exhaust varies depending on the type of fuel, engine power settings, and ambient air conditions. A high FA concentration at ground level due to a change in the fuel type, low temperature, and humidity, causes frequent severe eye respiratory irritation.

Higher-order power harmonics of pulsed electrical stimulation modulates corticospinal contribution of peripheral nerve stimulation.

PubMed

Chen, Chiun-Fan; Bikson, Marom; Chou, Li-Wei; Shan, Chunlei; Khadka, Niranjan; Chen, Wen-Shiang; Fregni, Felipe

2017-03-03

It is well established that electrical-stimulation frequency is crucial to determining the scale of induced neuromodulation, particularly when attempting to modulate corticospinal excitability. However, the modulatory effects of stimulation frequency are not only determined by its absolute value but also by other parameters such as power at harmonics. The stimulus pulse shape further influences parameters such as excitation threshold and fiber selectivity. The explicit role of the power in these harmonics in determining the outcome of stimulation has not previously been analyzed. In this study, we adopted an animal model of peripheral electrical stimulation that includes an amplitude-adapted pulse train which induces force enhancements with a corticospinal contribution. We report that the electrical-stimulation-induced force enhancements were correlated with the amplitude of stimulation power harmonics during the amplitude-adapted pulse train. In an exploratory analysis, different levels of correlation were observed between force enhancement and power harmonics of 20-80 Hz (r = 0.4247, p = 0.0243), 100-180 Hz (r = 0.5894, p = 0.0001), 200-280 Hz (r = 0.7002, p < 0.0001), 300-380 Hz (r = 0.7449, p < 0.0001), 400-480 Hz (r = 0.7906, p < 0.0001), 500-600 Hz (r = 0.7717, p < 0.0001), indicating a trend of increasing correlation, specifically at higher order frequency power harmonics. This is a pilot, but important first demonstration that power at high order harmonics in the frequency spectrum of electrical stimulation pulses may contribute to neuromodulation, thus warrant explicit attention in therapy design and analysis.

Amateur boxing: physical and physiological attributes.

PubMed

Chaabène, Helmi; Tabben, Montassar; Mkaouer, Bessem; Franchini, Emerson; Negra, Yassine; Hammami, Mehrez; Amara, Samiha; Chaabène, Raja Bouguezzi; Hachana, Younés

2015-03-01

Boxing is one of the oldest combat sports. The aim of the current review is to critically analyze the amateur boxer's physical and physiological characteristics and to provide practical recommendations for training as well as new areas of scientific research. High-level male and female boxers show a propensity for low body fat levels. Although studies on boxer somatotypes are limited, the available information shows that elite-level male boxers are characterized by a higher proportion of mesomorphy with a well-developed muscle mass and a low body fat level. To help support the overall metabolic demands of a boxing match and to accelerate the recovery process between rounds, athletes of both sexes require a high level of cardiorespiratory fitness. International boxers show a high peak and mean anaerobic power output. Muscle strength in both the upper and lower limbs is paramount for a fighter's victory and is one of the keys to success in boxing. As boxing punches are brief actions and very dynamic, high-level boxing performance requires well-developed muscle power in both the upper and lower limbs. Albeit limited, the available studies reveal that isometric strength is linked to high-level boxing performance. Future investigations into the physical and physiological attributes of boxers are required to enrich the current data set and to help create a suitable training program.

Theory, Design and Operation of a High-Power Second - Gyro-Twt Amplifier.

NASA Astrophysics Data System (ADS)

Wang, Qinsong

1995-01-01

Based on the cyclotron resonance maser (CRM) instability, the gyrotron traveling wave tube (gyro-TWT) amplifier is an efficient high power microwave and millimeter wave coherent radiation source. As evidenced in previous experiments, gyro-TWTs, however, can be very susceptible to spontaneous oscillations, and their output powers have thus been limited to relatively low levels. In this dissertation work, thorough theoretical and experimental studies have been conducted to demonstrate and confirm a novel "marginal stability design" (MSD) concept that a harmonic gyro-TWT amplifier is more stable to spontaneous oscillation than a fundamental harmonic gyro-TWT amplifier. Since their interactions are, in general, weaker and allow higher levels of electron beam current, harmonic gyro-TWTs can yield, in principle, a significantly higher RF output power than a fundamental gyro-TWT. The study results also show that a magnetron injection gun (MIG) type electron beam is applicable to harmonic gyro-TWTs. A complete analytic linear theory employing Laplace transforms and a three dimensional nonlinear theory using a slow time-scale formalism are developed in Chapt. 2 for the general CRM interaction to address the issue of stability. Two designs were developed to demonstrate the MSD procedure. The design and development of the proof -of-principle experiment are discussed in Chapt. 3. The accompanying cold test results indicate that all the components have met their respective design goals. The RF diagnostic circuit employed to characterize the gyro-TWT amplifier is also described. Chapter 4 presents the hot-test results of the second-harmonic TE_{21} gyro-TWT amplifier experiment in which an 80 kV, 20 A MIG beam with alpha(equivupsilon _|/upsilon_|) = 1 was used to generate a peak RF output power of 207 kW in Ku-band with an efficiency of 12.9%. In addition, the saturated gain is 16 dB, the small signal gain is 22 dB, the measured bandwidth is 2.1%, and the amplifier was zero-drive stable. As pointed out in Chapt. 5, the theoretical and experimental studies conducted in this work have successfully realized their objectives. Further improvements to the current proof-of-principle experiment and an increase in the operating frequency by operating at an even higher cyclotron harmonic are promising and worthy of future efforts.

Reliability analysis of component-level redundant topologies for solid-state fault current limiter

NASA Astrophysics Data System (ADS)

Farhadi, Masoud; Abapour, Mehdi; Mohammadi-Ivatloo, Behnam

2018-04-01

Experience shows that semiconductor switches in power electronics systems are the most vulnerable components. One of the most common ways to solve this reliability challenge is component-level redundant design. There are four possible configurations for the redundant design in component level. This article presents a comparative reliability analysis between different component-level redundant designs for solid-state fault current limiter. The aim of the proposed analysis is to determine the more reliable component-level redundant configuration. The mean time to failure (MTTF) is used as the reliability parameter. Considering both fault types (open circuit and short circuit), the MTTFs of different configurations are calculated. It is demonstrated that more reliable configuration depends on the junction temperature of the semiconductor switches in the steady state. That junction temperature is a function of (i) ambient temperature, (ii) power loss of the semiconductor switch and (iii) thermal resistance of heat sink. Also, results' sensitivity to each parameter is investigated. The results show that in different conditions, various configurations have higher reliability. The experimental results are presented to clarify the theory and feasibility of the proposed approaches. At last, levelised costs of different configurations are analysed for a fair comparison.

Kinetic comparison of older men and women during walk-to-stair descent transition.

PubMed

Singhal, Kunal; Kim, Jemin; Casebolt, Jeffrey; Lee, Sangwoo; Han, Ki Hoon; Kwon, Young-Hoo

2014-09-01

Stair walking is one of the most challenging tasks for older adults, with women reporting higher incidence of falls. The purpose of this study was to investigate the gender differences in kinetics during stair descent transition. Twenty-eight participants (12 male and 16 female; 68.5 and 69.0 years of mean age, respectively) performed stair descent from level walking in a step-over-step manner at a self-selected speed over a custom-made three-step staircase with embedded force plates. Kinematic and force data were combined using inverse dynamics to generate kinetic data for gender comparison. The top and the first step on the staircase were chosen for analysis. Women showed a higher trail leg peak hip abductor moment (-1.0 Nm/kg), lower trail leg peak knee extensor moment and eccentric power (0.74 Nm/kg and 3.15 W/kg), and lower peak concentric power at trail leg ankle joint (1.29 W/kg) as compared to men (p<0.05; -0.82 Nm/kg, 0.89 Nm/kg, 3.83 W/kg, and 1.78 W/kg, respectively). The lead leg knee eccentric power was also lower in women (p<0.05). This decreased ability to exert knee control during stair descent transition may predispose women to a higher risk of fall. Copyright © 2014 Elsevier B.V. All rights reserved.

POWER for reproductive health: results from a social marketing campaign promoting female and male condoms.

PubMed

Bull, Sheana S; Posner, Samuel F; Ortiz, Charlene; Beaty, Brenda; Benton, Kathryn; Lin, Lillian; Pals, Sherri L; Evans, Tom

2008-07-01

To evaluate effects of a 6-month social marketing campaign on awareness of, attitudes toward and use of female as well as male condoms for 15-25 year-old-women. Using a time-space sampling methodology, we conducted a cross-sectional survey of 3407 women at pre-campaign in 12 western U.S. neighborhoods on female and male condom awareness, attitudes, and use. Six of the 12 study neighborhoods were randomly selected to receive the POWER social marketing campaign designed to impact condom knowledge, attitudes, and use. The campaign was followed with another cross-sectional survey of 3,003 women in all 12 study neighborhoods on condom knowledge, attitudes, use and awareness of POWER materials. We compared pre-and post-campaign surveys to determine the efficacy of POWER and conducted post hoc analyses on post-campaign data to determine if exposure to POWER was related to higher levels of positive condom attitudes and norms and condom use. We found no differences between neighborhoods with and without the POWER campaign with regard to our primary outcomes. To diagnose reasons for this null effect, we examined outcomes post hoc examining the influence of POWER exposure. Post hoc analyses show some evidence that exposure to POWER was associated with condom use. In the context of the nested trial, this raises concerns that post test only evaluations are limited. Establishing the efficacy of a social marketing campaign is challenging. This group randomized trial showed a null effect. Social marketing campaigns may need to have more media channels and saturation before they can show behavioral effects. Using a nested design with randomization at the community level and probability sampling introduces rigor not commonly seen in evaluations of social marketing campaigns.

(De)Constructing Power in Higher Education Governance Structures: An Analysis of Representation and Roles in Governing Bodies

ERIC Educational Resources Information Center

Bótas, Paulo Charles Pimentel; Huisman, Jeroen

2012-01-01

This article explores how power relations are constructed in the governance of higher education institutions. It examines and deconstructs, from a Foucauldian perspective, power relations and mechanisms in the relationship between the state and higher education institutions, and between academic and management staff. This research article…

Thermoelectric power generator for variable thermal power source

DOEpatents

Bell, Lon E; Crane, Douglas Todd

2015-04-14

Traditional power generation systems using thermoelectric power generators are designed to operate most efficiently for a single operating condition. The present invention provides a power generation system in which the characteristics of the thermoelectrics, the flow of the thermal power, and the operational characteristics of the power generator are monitored and controlled such that higher operation efficiencies and/or higher output powers can be maintained with variably thermal power input. Such a system is particularly beneficial in variable thermal power source systems, such as recovering power from the waste heat generated in the exhaust of combustion engines.

The wave-tide-river delta classification revisited: Introducing the effects of Humans on delta equilibriu

NASA Astrophysics Data System (ADS)

Besset, M.; Anthony, E.; Sabatier, F.

2016-12-01

The influence of physical processes on river deltas has long been identified, mainly on the basis of delta morphology. A cuspate delta is considered as wave-dominated, a delta with finger-like extensions is characterized as river-dominated, and a delta with estuarine re-entrants is considered tide-dominated (Galloway, 1975). The need for a more quantitative classification is increasingly recognized, and is achievable through quantified combinations, a good example being Syvitski and Saito (2007) wherein the joint influence of marine power - wave and tides - is compared to that of river influence. This need is further justified as deltas become more and more vulnerable. Going forward from the Syvitski and Saito (2007) approach, we confront, from a large database on 60 river deltas, the maximum potential power of waves and the tidal range (both representing marine power), and the specific stream power and river sediment supply reflecting an increasingly human-impacted river influence. The results show that 45 deltas (75%) have levels of marine power that are significantly higher than those of specific stream power. Five deltas have sufficient stream power to counterbalance marine power but a present sediment supply inadequate for them to be statistically considered as river-dominated. Six others have a sufficient sediment supply but a specific stream power that is not high enough for them to be statistically river-dominated. A major manifestation of the interplay of these parameters is accelerated delta erosion worldwide, shifting the balance towards marine power domination. Deltas currently eroding are mainly influenced by marine power (93%), and small deltas (< 300 km2 of deltaic protuberance) are the most vulnerable (82%). These high levels of erosion domination, compounded by accelerated subsidence, are related to human-induced sediment supply depletion and changes in water discharge in the face of the sediment-dispersive capacity of waves and currents.

MW-Class Electric Propulsion System Designs

NASA Technical Reports Server (NTRS)

LaPointe, Michael R.; Oleson, Steven; Pencil, Eric; Mercer, Carolyn; Distefano, Salvador

2011-01-01

Electric propulsion systems are well developed and have been in commercial use for several years. Ion and Hall thrusters have propelled robotic spacecraft to encounters with asteroids, the Moon, and minor planetary bodies within the solar system, while higher power systems are being considered to support even more demanding future space science and exploration missions. Such missions may include orbit raising and station-keeping for large platforms, robotic and human missions to near earth asteroids, cargo transport for sustained lunar or Mars exploration, and at very high-power, fast piloted missions to Mars and the outer planets. The Advanced In-Space Propulsion Project, High Efficiency Space Power Systems Project, and High Power Electric Propulsion Demonstration Project were established within the NASA Exploration Technology Development and Demonstration Program to develop and advance the fundamental technologies required for these long-range, future exploration missions. Under the auspices of the High Efficiency Space Power Systems Project, and supported by the Advanced In-Space Propulsion and High Power Electric Propulsion Projects, the COMPASS design team at the NASA Glenn Research Center performed multiple parametric design analyses to determine solar and nuclear electric power technology requirements for representative 300-kW class and pulsed and steady-state MW-class electric propulsion systems. This paper describes the results of the MW-class electric power and propulsion design analysis. Starting with the representative MW-class vehicle configurations, and using design reference missions bounded by launch dates, several power system technology improvements were introduced into the parametric COMPASS simulations to determine the potential system level benefits such technologies might provide. Those technologies providing quantitative system level benefits were then assessed for technical feasibility, cost, and time to develop. Key assumptions and primary results of the COMPASS MW-class electric propulsion power system study are reported, and discussion is provided on how the analysis might be used to guide future technology investments as NASA moves to more capable high power in-space propulsion systems.

Measurements of ultrafine particles and other vehicular pollutants inside school buses in South Texas

NASA Astrophysics Data System (ADS)

Zhang, Qunfang; Zhu, Yifang

2010-01-01

Increasing evidence has demonstrated toxic effects of vehicular emitted ultrafine particles (UFPs, diameter < 100 nm), with the highest human exposure usually occurring on and near roadways. Children are particularly at risk due to immature respiratory systems and faster breathing rates. In this study, children's exposure to in-cabin air pollutants, especially UFPs, was measured inside four diesel-powered school buses. Two 1990 and two 2006 model year diesel-powered school buses were selected to represent the age extremes of school buses in service. Each bus was driven on two routine bus runs to study school children's exposure under different transportation conditions in South Texas. The number concentration and size distribution of UFPs, total particle number concentration, PM 2.5, PM 10, black carbon (BC), CO, and CO 2 levels were monitored inside the buses. The average total particle number concentrations observed inside the school buses ranged from 7.3 × 10 3 to 3.4 × 10 4 particles cm -3, depending on engine age and window position. When the windows were closed, the in-cabin air pollutants were more likely due to the school buses' self-pollution. The 1990 model year school buses demonstrated much higher air pollutant concentrations than the 2006 model year ones. When the windows were open, the majority of in-cabin air pollutants came from the outside roadway environment with similar pollutant levels observed regardless of engine ages. The highest average UFP concentration was observed at a bus transfer station where approximately 27 idling school buses were queued to load or unload students. Starting-up and idling generated higher air pollutant levels than the driving state. Higher in-cabin air pollutant concentrations were observed when more students were on board.

Space Station module Power Management And Distribution (PMAD) system

NASA Technical Reports Server (NTRS)

Walls, Bryan

1990-01-01

This project consists of several tasks which are unified toward experimentally demonstrating the operation of a highly autonomous, user-supportive power management and distribution system for Space Station Freedom (SSF) habitation/laboratory modules. This goal will be extended to a demonstration of autonomous, cooperative power system operation for the whole SSF power system through a joint effort with NASA's Lewis Research Center, using their Autonomous Power System. Short term goals for the space station module power management and distribution include having an operational breadboard reflecting current plans for SSF, improving performance of the system communications, and improving the organization and mutability of the artificial intelligence (AI) systems. In the middle term, intermediate levels of autonomy will be added, user interfaces will be modified, and enhanced modeling capabilities will be integrated in the system. Long term goals involve conversion of all software into Ada, vigorous verification and validation efforts and, finally, seeing an impact of this research on the operation of SSF. Conversion of the system to a DC Star configuration is now in progress, and should be completed by the end of October, 1989. This configuration reflects the latest SSF module architecture. Hardware is now being procured which will improve system communications significantly. The Knowledge-Based Management System (KBMS) is initially developed and the rules from FRAMES have been implemented in the KBMS. Rules in the other two AI systems are also being grouped modularly, making them more tractable, and easier to eventually move into the KBMS. Adding an intermediate level of autonomy will require development of a planning utility, which will also be built using the KBMS. These changes will require having the user interface for the whole system available from one interface. An Enhanced Model will be developed, which will allow exercise of the system through the interface without requiring all of the power hardware to be operational. The functionality of the AI systems will continue to be advanced, including incipient failure detection. Ada conversion will begin with the lowest level processor (LLP) code. Then selected pieces of the higher level functionality will be recorded in Ada and, where possible, moved to the LLP level. Validation and verification will be done on the Ada code, and will complete sometimes after completion of the Ada conversion.

Perceptions of Declining Classmate and Teacher Support Following the Transition to High School: Potential Correlates of Increasing Student Mental Health Difficulties

ERIC Educational Resources Information Center

De Wit, David J.; Karioja, Kim; Rye, B. J.; Shain, Martin

2011-01-01

Emotional support from classmates and teachers is a powerful protective factor in averting or reducing student mental health problems. Yet, longitudinal evidence indicates that there is decreased support from these groups as students advance to higher grade levels, a change that may be linked to diminishing mental health. This study followed 2,616…

Gamma power and cognition in patients with schizophrenia and their first-degree relatives.

PubMed

Díez, Álvaro; Suazo, Vanessa; Casado, Pilar; Martín-Loeches, Manuel; Molina, Vicente

2014-01-01

Gamma oscillations are essential for functional neural assembly formation underlying higher cerebral functions. Previous studies concerning gamma band power in schizophrenia have yielded diverse results. In this study, we assessed gamma band power in minimally treated patients with schizophrenia, their first-degree relatives and healthy controls during an oddball paradigm performance, as well as the relation between gamma power and cognitive performance. We found a higher gamma power in the patient group than in the healthy controls at the P3, P4, Fz, Pz and T5 sites. Compared with their relatives, gamma power in the patients was only marginally higher over P3 and P4. We found a nearly significant inverse association between gamma power at F4 and Tower of London performance in the patients, as well as a significant inverse association between gamma power at T5 and verbal memory and working memory scores in the relatives. These results support higher total gamma power in association with schizophrenia and its inverse association with cognitive performance in patients and their first-degree relatives.

The Lipid Parameters and Lipoprotein(a) Excess in Hashimoto Thyroiditis.

PubMed

Yetkin, D O; Dogantekin, B

2015-01-01

Objective. The risk of atherosclerotic heart disease is increased in autoimmune thyroiditis, although the reason is not clear. Lipoprotein(a) (Lp(a)) excess has been identified as a powerful predictor of premature atherosclerotic vascular diseases. The aim of this study is to investigate the relationship between Lp(a) levels and thyroid hormones in Hashimoto patients. Method. 154 premenopausal female Hashimoto patients (48 patients with overthypothyroid (OH), 50 patients with subclinical hypothyroid (SH), and 56 patients with euthyroid Hashimoto to (EH)) were enrolled in this study. The control group consists of 50 age matched volunteers. In every group, thyroid function tests and lipid parameters with Lp(a) were measured. Lp(a) excess was defined as Lp(a) > 30 mg/dL. Results. Total-C, LDL-C, TG, and Lp(a) levels were increased in Hashimoto group. Total-C, LDL-C, and TG levels were higher in SH group than in the control group. Total-C and LDL-C levels were also higher in EH group compared to controls. Lp(a) levels were similar in SH and EH groups with controls. However, excess Lp(a) was more common in subclinical hypothyroid and euthyroid Hashimoto group than in the control group. Conclusion. The Total-C and LDL-C levels and excess Lp(a) were higher even in euthyroid Hashimoto patients. Thyroid autoimmunity may have some effect on Lp(a) and lipid metabolism.

The Lipid Parameters and Lipoprotein(a) Excess in Hashimoto Thyroiditis

PubMed Central

Yetkin, D. O.; Dogantekin, B.

2015-01-01

Objective. The risk of atherosclerotic heart disease is increased in autoimmune thyroiditis, although the reason is not clear. Lipoprotein(a) (Lp(a)) excess has been identified as a powerful predictor of premature atherosclerotic vascular diseases. The aim of this study is to investigate the relationship between Lp(a) levels and thyroid hormones in Hashimoto patients. Method. 154 premenopausal female Hashimoto patients (48 patients with overthypothyroid (OH), 50 patients with subclinical hypothyroid (SH), and 56 patients with euthyroid Hashimoto to (EH)) were enrolled in this study. The control group consists of 50 age matched volunteers. In every group, thyroid function tests and lipid parameters with Lp(a) were measured. Lp(a) excess was defined as Lp(a) > 30 mg/dL. Results. Total-C, LDL-C, TG, and Lp(a) levels were increased in Hashimoto group. Total-C, LDL-C, and TG levels were higher in SH group than in the control group. Total-C and LDL-C levels were also higher in EH group compared to controls. Lp(a) levels were similar in SH and EH groups with controls. However, excess Lp(a) was more common in subclinical hypothyroid and euthyroid Hashimoto group than in the control group. Conclusion. The Total-C and LDL-C levels and excess Lp(a) were higher even in euthyroid Hashimoto patients. Thyroid autoimmunity may have some effect on Lp(a) and lipid metabolism. PMID:26064115

Evolving Righteousness in a Corrupt World

PubMed Central

Duéñez-Guzmán, Edgar A.; Sadedin, Suzanne

2012-01-01

Punishment offers a powerful mechanism for the maintenance of cooperation in human and animal societies, but the maintenance of costly punishment itself remains problematic. Game theory has shown that corruption, where punishers can defect without being punished themselves, may sustain cooperation. However, in many human societies and some insect ones, high levels of cooperation coexist with low levels of corruption, and such societies show greater wellbeing than societies with high corruption. Here we show that small payments from cooperators to punishers can destabilize corrupt societies and lead to the spread of punishment without corruption (righteousness). Righteousness can prevail even in the face of persistent power inequalities. The resultant righteous societies are highly stable and have higher wellbeing than corrupt ones. This result may help to explain the persistence of costly punishing behavior, and indicates that corruption is a sub-optimal tool for maintaining cooperation in human societies. PMID:22984510

Effects of Ultrasonic Parameters on the Crystallization Behavior of Virgin Coconut Oil.

PubMed

Wu, Linhe; Cao, Jun; Bai, Xinpeng; Chen, Haiming; Zhang, Yuxiang; Wu, Qian

2016-12-01

Crystallization behavior of virgin coconut oil (VCO) in the absence and presence of ultrasonic treatment under a temperature gradient field was investigated. The effects of ultrasonic parameters on the crystallization behavior of VCO were studied by differential scanning calorimetry, ultraviolet/visible spectrophotometry and polarized light microscopy. The thermal effect of the ultrasonic treatment was also increased at higher power levels. Therefore, the optimal power level was determined at approximately 36 W. Induction time reduced evidently and the crystallization rate was accelerated under ultrasonic treatment at crystallization temperature (T c ) above 15°C. However, no significant difference in induction time was noted at 13°C. The result of morphological studies showed that the growth mechanism of crystals was significantly changed. Meanwhile, smaller and uniform crystals were produced by the ultrasonic treatment. This study shows a novel technique to accelerate the crystallization rate and alter the growth mechanism of VCO crystals.

Modelling of magnetostriction of transformer magnetic core for vibration analysis

NASA Astrophysics Data System (ADS)

Marks, Janis; Vitolina, Sandra

2017-12-01

Magnetostriction is a phenomenon occurring in transformer core in normal operation mode. Yet in time, it can cause the delamination of magnetic core resulting in higher level of vibrations that are measured on the surface of transformer tank during diagnostic tests. The aim of this paper is to create a model for evaluating elastic deformations in magnetic core that can be used for power transformers with intensive vibrations in order to eliminate magnetostriction as a their cause. Description of the developed model in Matlab and COMSOL software is provided including restrictions concerning geometry and properties of materials, and the results of performed research on magnetic core anisotropy are provided. As a case study modelling of magnetostriction for 5-legged 200 MVA power transformer with the rated voltage of 13.8/137kV is conducted, based on which comparative analysis of vibration levels and elastic deformations is performed.

Effect of rotor design tip speed on noise of a 1.21 pressure ratio model fan under static conditions

NASA Technical Reports Server (NTRS)

Loeffler, I. J.; Lieblein, S.; Stockman, N. O.

1973-01-01

Preliminary results are presented for a reverberant-field noise investigation of three fan stages designed for the same overall total pressure ratio of 1.21 at different rotor tip speeds (750, 900, and 1050 ft/sec). The stages were tested statically in a 15-inch-diameter model lift fan installed in a wing pod located in the test section of a wind tunnel. Although the fan stages produced essentially the same design pressure ratio, marked differences were observed in the variation of fan noise with fan operating speed. At design speed, the forward-radiated sound power level was approximately the same for the 750 ft/sec and 900 ft/sec stages. For the 1050 ft/sec stage, the design-speed forward-radiated power level was about 7 db higher due to the generation of multiple pure tone noise.

Effect of rotor design tip speed on noise of a 1.21 pressure ratio model fan under static conditions

NASA Technical Reports Server (NTRS)

Loeffler, I. J.; Lieblein, S.; Stockman, N. O.

1973-01-01

Preliminary results are presented for a reverberant-field noise investigation of three fan stages designed for the same overall total pressure ratio of 1.21 at different rotor tip speeds (750, 900, and 1050 fps). The stages were tested statically in a 15-in.-dia model lift fan installed in a wing pod located in the test section of a wind tunnel. Although the fan stages produced essentially the same design pressure ratio, marked differences were observed in the variation of fan noise with fan operating speed. At design speed, the forward-radiated sound power level was approximately the same for the 750 and 900 fps stages. For the 1050 fps stage, the design-speed forward-radiated power level was about 7 dB higher due to the generation of multiple pure tone noise.

Geoscience Laser Altimeter System (GLAS) Instrument: Flight Loop Heat Pipe (LHP) Acceptance Thermal Vacuum Test

NASA Technical Reports Server (NTRS)

Baker, Charles; Butler, Dan; Ku, Jentung; Grob, Eric; Swanson, Ted; Nikitkin, Michael; Powers, Edward I. (Technical Monitor)

2001-01-01

Two loop heat pipes (LHPs) are to be used for tight thermal control of the Geoscience Laser Altimeter System (GLAS) instrument, planned for flight in late 2001. The LHPs are charged with Propylene as a working fluid. One LHP will be used to transport 110 W from a laser to a radiator, the other will transport 160 W from electronic boxes to a separate radiator. The application includes a large amount of thermal mass in each LHP system and low initial startup powers. The initial design had some non-ideal flight design compromises, resulted in a less than ideal charge level for this design concept with a symmetrical secondary wick. This less than ideal charge was identified as the source of inadequate performance of the flight LHPs during the flight thermal vacuum test in October of 2000. We modified the compensation chamber design, re-built and charged the LHPs for a final LHP acceptance thermal vacuum test. This test performed March of 2001 was 100% successful. This is the last testing to be performed on the LHPs prior to instrument thermal vacuum test. This sensitivity to charge level was shown through varying the charge on a Development Model Loop Heat Pipe (DM LHP) and evaluating performance at various fill levels. At lower fills similar to the original charge in the flight units, the same poor performance was observed. When the flight units were re-designed and filled to the levels similar to the initial successful DM LHP test, the flight units also successfully fulfilled all requirements. This final flight Acceptance test assessed performance with respect to startup, low power operation, conductance, and control heater power, and steady state control. The results of the testing showed that both LHPs operated within specification. Startup on one of the LHPs was better than the other LHP because of the starter heater placement and a difference in evaporator design. These differences resulted in a variation in the achieved superheat prior to startup. The LHP with the lower superheat was sensitive to the thermal environment around the compensation chamber, while the LHP with the higher superheat (similar in design to DM LHP) was not. In response to the test results the placement of the starter heater will be optimized for the flight instrument testing for higher achieved superheat. This presentation discusses startup behavior, overall conductance of a radiator system, low power operation, high power operation, temperature control stability, and control heater power requirements as measured during this acceptance thermal vacuum test. A brief summary of 'lessons learned' will be included.

Outer Planet Science Missions enabled by Solar Power

NASA Astrophysics Data System (ADS)

Kaplan, M.; Klaus, K.; Smith, D. B.

2009-12-01

Our studies demonstrate that New Frontiers-class science missions to the Jupiter and Saturn systems are possible with commercial solar powered space craft. These spacecraft are flight proven with more than 60 years of in-space operation and are equipped with highly efficient solar arrays capable of up to 25kW in low earth orbit. Such a vehicle could generate nearly 1kW in the Jovian System. Our analysis shows substantially greater power at the end of mission with this solar array system than the system that is planned for use in the Europa Jupiter System Flagship mission study. In the next few years, a new solar array technology will be developed and demonstrated by DARPA that will provide even higher power. DARPA’s Fast Access Space Testbed (FAST) program objective is to develop a revolutionary approach to spacecraft high power generation. This high power generation Subsystem, when combined with electric propulsion, will form the technological basis for a light weight, high power, highly mobile spacecraft platform. The FAST program will demonstrate the implementation of solar concentrators and high flux solar cells in conjunction with high specific impulse electric propulsion, to produce a high performance, lightweight power and propulsion system. A basic FAST spacecraft design provides about 60 kW in LEO, which scales to > 2 kW at 5 AU, or a little less than 1 kW at 10 AU. In principle, higher power levels (120 kW or even 180kW at 1 AU) could be accommodated with this technology. We envision missions using this FAST array and NASA’s NEXT engines for solar electric propulsion (SEP) Jovian and Saturn system maneuvers. We envision FAST arrays to cost in the tens of millions, making this an affordable, plutonium-free way to do outer planets science. Continued funding will mean flight experiments conducted in the 2012 timeframe that could make this technology flight proven for the New Frontiers 4 opportunity.

Cancer genetic counseling: communication and counselees' post-visit satisfaction, cognitions, anxiety, and needs fulfillment.

PubMed

Pieterse, Arwen H; van Dulmen, Alexandra M; Beemer, Frits A; Bensing, Jozien M; Ausems, Margreet G E M

2007-02-01

Little is known about the relation between communication during cancer genetic counseling and outcome. We assessed associations between counselor-counselee communication and counselee satisfaction, cognitions, anxiety, and fulfillment of major needs, corrected for pre-visit levels as appropriate. In total 171 consecutive new counselees, mainly referred for breast or colon cancer, received pre- and post-visit questionnaires assessing needs/fulfillment, knowledge, perceived control (PPC), anxiety (STAI), and satisfaction. Initial visits were videotaped and counselor eye gaze was recorded. Verbal communication was rated by Roter Interaction Analysis System (RIAS). Asking more medical questions was associated with lower satisfaction levels. Receiving more medical information was related to higher correct knowledge scores, higher reported fulfillment of some needs, and unrelated to perceptions of control. Receiving more psychosocial information and longer counselor eye gaze were related to higher anxiety scores. Longer visits were related to higher correct knowledge scores. Providing medical information appears the most powerful communication aspect to increase counselee satisfaction and address needs. More research is needed on how to address adequately (emotional) needs and increase feelings of control.

Kickboxing review: anthropometric, psychophysiological and activity profiles and injury epidemiology

PubMed Central

Chaabene, H; Miarka, B; Franchini, E; Chamari, K; Cheour, F

2017-01-01

Kickboxing is one of the modern combat sports. The psychophysiological demands of a kickboxing competition require athletes to achieve high thresholds of several aspects of physical fitness. The aim of the current review is to critically analyse and appraise the kickboxer’s anthropometric, physiological, physical and psychological attributes with the activity profile and injury epidemiology in order to provide practical recommendations for training as well as new areas of scientific research. The available information shows that both amateur and elite-level male kickboxers are characterized by a higher proportion of mesomorphy with a well-developed muscle mass and low body fat percentage. While there is some variation in the maximum oxygen uptake of kickboxers, moderate to high cardio-respiratory levels are reported for these athletes. Regardless of kickboxers’ level, a high peak and mean anaerobic power output were reported. High-level kickboxing performance also requires well-developed muscle power in both the upper and lower limbs. Psychological factors contribute to success that requires high levels of self-confidence, motivation, dispositional hope and optimism, mental toughness/resiliency, and adaptive perfectionism. Psychological attributes also distinguished successful from less successful kickboxers. The activity-to-rest ratio was higher in elite (1:1) than both amateur and national-level (from 1:2 to 1:5) kickboxers, with no significant differences between rounds (round 1=1:4, and rounds 2 and 3=1:5) as well as between winners and losers in amateur and national-level simulated combats. These particular psychophysiological characteristics and performance aspects of kickboxers influence performance and could serve as guidance for training. Finally, kickboxing is characterized by chronic repetitive head trauma, which causes hypopituitarism due to traumatic brain injury (TBI). Future investigations into the physical, physiological and psychological characteristics related to age, gender and competitive levels of kickboxers are required to enrich the current knowledge and to help create the most suitable training programme. PMID:28566813

Kickboxing review: anthropometric, psychophysiological and activity profiles and injury epidemiology.

PubMed

Slimani, M; Chaabene, H; Miarka, B; Franchini, E; Chamari, K; Cheour, F

2017-06-01

Kickboxing is one of the modern combat sports. The psychophysiological demands of a kickboxing competition require athletes to achieve high thresholds of several aspects of physical fitness. The aim of the current review is to critically analyse and appraise the kickboxer's anthropometric, physiological, physical and psychological attributes with the activity profile and injury epidemiology in order to provide practical recommendations for training as well as new areas of scientific research. The available information shows that both amateur and elite-level male kickboxers are characterized by a higher proportion of mesomorphy with a well-developed muscle mass and low body fat percentage. While there is some variation in the maximum oxygen uptake of kickboxers, moderate to high cardio-respiratory levels are reported for these athletes. Regardless of kickboxers' level, a high peak and mean anaerobic power output were reported. High-level kickboxing performance also requires well-developed muscle power in both the upper and lower limbs. Psychological factors contribute to success that requires high levels of self-confidence, motivation, dispositional hope and optimism, mental toughness/resiliency, and adaptive perfectionism. Psychological attributes also distinguished successful from less successful kickboxers. The activity-to-rest ratio was higher in elite (1:1) than both amateur and national-level (from 1:2 to 1:5) kickboxers, with no significant differences between rounds (round 1=1:4, and rounds 2 and 3=1:5) as well as between winners and losers in amateur and national-level simulated combats. These particular psychophysiological characteristics and performance aspects of kickboxers influence performance and could serve as guidance for training. Finally, kickboxing is characterized by chronic repetitive head trauma, which causes hypopituitarism due to traumatic brain injury (TBI). Future investigations into the physical, physiological and psychological characteristics related to age, gender and competitive levels of kickboxers are required to enrich the current knowledge and to help create the most suitable training programme.

Developing a stability assessment method for power electronics-based microgrids

NASA Astrophysics Data System (ADS)

Austin, Peter M.

Modern microgrids with microsources and energy storage are dependent on power electronics for control and regulation. Under certain circumstances power electronics can be destabilizing to the system due to an effect called negative incremental impedance. A careful review of the theory and literature on the subject is presented. This includes stability criteria for both AC and DC systems, as well as a discussion on the limitations posed by the analysis. A method to integrate stability assessment with higher-level microgrid architectural design is proposed. Crucial to this is impedance characterization of individual components, which was accomplished through simulation. DC and AC impedance measurement blocks were created in Matlab simulink to automate the process. A detailed switching-level model of a DC microgrid was implemented in simulink, including wind turbine microsource, battery storage, and three phase inverter. Maximum power point tracking (MPPT) was included to maximize the efficiency of the turbine and was implemented through three rectifier alternatives and control schemes. The stability characteristics of each was compared in the final analysis. Impedance data was collected individually from the components and used to assess stability in the system as a whole. The results included the assessment of stability, margin, and unstable operating points to demonstrate the feasibility of the proposed approach.

Influence of gender constancy and social power on sex-linked modeling.

PubMed

Bussey, K; Bandura, A

1984-12-01

Competing predictions derived from cognitive-developmental theory and social learning theory concerning sex-linked modeling were tested. In cognitive-developmental theory, gender constancy is considered a necessary prerequisite for the emulation of same-sex models, whereas according to social learning theory, sex-role development is promoted through a vast system of social influences with modeling serving as a major conveyor of sex role information. In accord with social learning theory, even children at a lower level of gender conception emulated same-sex models in preference to opposite-sex ones. Level of gender constancy was associated with higher emulation of both male and female models rather than operating as a selective determinant of modeling. This finding corroborates modeling as a basic mechanism in the sex-typing process. In a second experiment we explored the limits of same-sex modeling by pitting social power against the force of collective modeling of different patterns of behavior by male and female models. Social power over activities and rewarding resources produced cross-sex modeling in boys, but not in girls. This unexpected pattern of cross-sex modeling is explained by the differential sex-typing pressures that exist for boys and girls and socialization experiences that heighten the attractiveness of social power for boys.

Weavable, Conductive Yarn-Based NiCo//Zn Textile Battery with High Energy Density and Rate Capability.

PubMed

Huang, Yan; Ip, Wing Shan; Lau, Yuen Ying; Sun, Jinfeng; Zeng, Jie; Yeung, Nga Sze Sea; Ng, Wing Sum; Li, Hongfei; Pei, Zengxia; Xue, Qi; Wang, Yukun; Yu, Jie; Hu, Hong; Zhi, Chunyi

2017-09-26

With intrinsic safety and much higher energy densities than supercapacitors, rechargeable nickel/cobalt-zinc-based textile batteries are promising power sources for next generation personalized wearable electronics. However, high-performance wearable nickel/cobalt-zinc-based batteries are rarely reported because there is a lack of industrially weavable and knittable highly conductive yarns. Here, we use scalably produced highly conductive yarns uniformly covered with zinc (as anode) and nickel cobalt hydroxide nanosheets (as cathode) to fabricate rechargeable yarn batteries. They possess a battery level capacity and energy density, as well as a supercapacitor level power density. They deliver high specific capacity of 5 mAh cm -3 and energy densities of 0.12 mWh cm -2 and 8 mWh cm -3 (based on the whole solid battery). They exhibit ultrahigh rate capabilities of 232 C (liquid electrolyte) and 116 C (solid electrolyte), which endows the batteries excellent power densities of 32.8 mW cm -2 and 2.2 W cm -3 (based on the whole solid battery). These are among the highest values reported so far. A wrist band battery is further constructed by using a large conductive cloth woven from the conductive yarns by a commercial weaving machine. It powers various electronic devices successfully, enabling dual functions of wearability and energy storage.

High-Capacity Communications from Martian Distances

NASA Technical Reports Server (NTRS)

Williams, W. Dan; Collins, Michael; Hodges, Richard; Orr, Richard S.; Sands, O. Scott; Schuchman, Leonard; Vyas, Hemali

2007-01-01

High capacity communications from Martian distances, required for the envisioned human exploration and desirable for data-intensive science missions, is challenging. NASA s Deep Space Network currently requires large antennas to close RF telemetry links operating at kilobit-per-second data rates. To accommodate higher rate communications, NASA is considering means to achieve greater effective aperture at its ground stations. This report, focusing on the return link from Mars to Earth, demonstrates that without excessive research and development expenditure, operational Mars-to-Earth RF communications systems can achieve data rates up to 1 Gbps by 2020 using technology that today is at technology readiness level (TRL) 4-5. Advanced technology to achieve the needed increase in spacecraft power and transmit aperture is feasible at an only moderate increase in spacecraft mass and technology risk. In addition, both power-efficient, near-capacity coding and modulation and greater aperture from the DSN array will be required. In accord with these results and conclusions, investment in the following technologies is recommended:(1) lightweight (1 kg/sq m density) spacecraft antenna systems; (2) a Ka-band receive ground array consisting of relatively small (10-15 m) antennas; (3) coding and modulation technology that reduces spacecraft power by at least 3 dB; and (4) efficient generation of kilowatt-level spacecraft RF power.

A ToF-SIMS and XPS study of protein adsorption and cell attachment across PEG-like plasma polymer films with lateral compositional gradients

NASA Astrophysics Data System (ADS)

Menzies, Donna J.; Jasieniak, Marek; Griesser, Hans J.; Forsythe, John S.; Johnson, Graham; McFarland, Gail A.; Muir, Benjamin W.

2012-12-01

In this work we report a detailed X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) study of poly(ethylene glycol) PEG-like chemical gradients deposited via plasma enhanced chemical vapour deposition (PECVD) at two different load powers using diethylene glycol dimethyl ether (DG) as a monomer. Principal component analysis (PCA) was applied to the ToF-SIMS data both before and after protein adsorption on the plasma polymer thin films. Results of the PCA loadings indicated a higher content of hydrocarbon fragments across the higher load power gradient, which adsorbed higher amounts of proteins. Gradients deposited at a lower load power retained a higher degree of monomer like functionality as did the central region directly underneath the knife edge electrode. Analysis of the adsorption of serum proteins (human serum albumin and fetal bovine serum) was monitored across the gradient films and increased with decreasing ether (PEG-like) film chemistries. The effect of protein incubation time on the levels adsorbed fetal bovine serum on the plasma polymer films was critical, with significantly more protein adsorbing after 24 hour incubation times on both gradient films. The attachment of HeLa cells on the gradients appeared to be dictated not only by the surface chemistry, but also by the adsorption of serum proteins. XPS analysis revealed that at surface ether concentrations of less than 70% in the gradient films, significant increases in protein and cell attachment were observed.