DC/DC Converter Stability Testing Study

NASA Technical Reports Server (NTRS)

Wang, Bright L.

2008-01-01

This report presents study results on hybrid DC/DC converter stability testing methods. An input impedance measurement method and a gain/phase margin measurement method were evaluated to be effective to determine front-end oscillation and feedback loop oscillation. In particular, certain channel power levels of converter input noises have been found to have high degree correlation with the gain/phase margins. It becomes a potential new method to evaluate stability levels of all type of DC/DC converters by utilizing the spectral analysis on converter input noises.

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.

Performance of 10-kW class xenon ion thrusters

NASA Technical Reports Server (NTRS)

Patterson, Michael J.; Rawlin, Vincent K.

1988-01-01

Presented are performance data for laboratory and engineering model 30 cm-diameter ion thrusters operated with xenon propellant over a range of input power levels from approximately 2 to 20 kW. Also presented are preliminary performance results obtained from laboratory model 50 cm-diameter cusp- and divergent-field ion thrusters operating with both 30 cm- amd 50 cm-diameter ion optics up to a 20 kW input power. These data include values of discharge chamber propellant and power efficiencies, as well as values of specific impulse, thruster efficiency, thrust and power. The operation of the 30 cm- and 50 cm-diameter ion optics are also discussed.

Reversing Optical Damage In LiNbO3 Switches

NASA Technical Reports Server (NTRS)

Gee, C. M.; Thurmond, G. D.

1985-01-01

One symptom of optical damage in Ti-diffused LiNbO3 directional-coupler switch reversed by temporarily raising input illumination to higher-thannormal power level. Healing phenomenon used to restore normal operation, increase operating-power rating, and stabilize operating characteristics at lower powers. Higher operating power is tolerated after treatment.

Peak power ratio generator

DOEpatents

Moyer, Robert D.

1985-01-01

A peak power ratio generator is described for measuring, in combination with a conventional power meter, the peak power level of extremely narrow pulses in the gigahertz radio frequency bands. The present invention in a preferred embodiment utilizes a tunnel diode and a back diode combination in a detector circuit as the only high speed elements. The high speed tunnel diode provides a bistable signal and serves as a memory device of the input pulses for the remaining, slower components. A hybrid digital and analog loop maintains the peak power level of a reference channel at a known amount. Thus, by measuring the average power levels of the reference signal and the source signal, the peak power level of the source signal can be determined.

Peak power ratio generator

DOEpatents

Moyer, R.D.

A peak power ratio generator is described for measuring, in combination with a conventional power meter, the peak power level of extremely narrow pulses in the gigahertz radio frequency bands. The present invention in a preferred embodiment utilizes a tunnel diode and a back diode combination in a detector circuit as the only high speed elements. The high speed tunnel diode provides a bistable signal and serves as a memory device of the input pulses for the remaining, slower components. A hybrid digital and analog loop maintains the peak power level of a reference channel at a known amount. Thus, by measuring the average power levels of the reference signal and the source signal, the peak power level of the source signal can be determined.

47 CFR 73.51 - Determining operating power.

Code of Federal Regulations, 2010 CFR

2010-10-01

... modulation Maximum rated carrier power Class of amplifier 0.70 Plate 1 kW or less .80 Plate 2.5 kW and over .35 Low level 0.25 kW and over B .65 Low level 0.25 kW and over BC1 .35 Grid 0.25 kW and over 1 All...'s input power directly from the RF voltage, RF current, and phase angle; or (2) calculating the...

High Power Microwave (HPM) and Ionizing Radiation Effects on CMOS Devices

DTIC Science & Technology

2010-03-01

24 xviii Symbol Page VIH minimum input voltage for proper high voltage output...38 VOH output voltage corresponding to VIH ...design. The high level at the input, VIH , along with VDD, define the maximum permitted “Logic 1” region, which allows for proper state change for a

Ka-Band Waveguide 2-Way Hybrid Combiner for MMIC Amplifiers with Unequal and Arbitrary Power Output Ratio

NASA Technical Reports Server (NTRS)

Simons, Rainee N (Inventor); Chevalier, Christine T (Inventor); Wintucky, Edwin G (Inventor); Freeman, Jon C (Inventor)

2016-01-01

One or more embodiments of the present invention describe an apparatus and method to combine unequal powers. The apparatus includes a first input port, a second input port, and a combiner. The first input port is operably connected to a first power amplifier and is configured to receive a first power from the first power amplifier. The second input port is operably connected to a second power amplifier and is configured to receive a second power from the second power amplifier. The combiner is configured to simultaneously receive the first power from the first input port and the second power from the second input port. The combiner is also configured to combine the first power and second power to produce a maximized power. The first power and second power are unequal.

Electric power distribution and load transfer system

NASA Technical Reports Server (NTRS)

Bradford, Michael P. (Inventor); Parkinson, Gerald W. (Inventor); Grant, Ross M. (Inventor)

1987-01-01

A power distribution system includes a plurality of power sources and load transfer units including transistors and diodes connected in series and leading to a common power output, each of the transistors being controller switchable subject to voltage levels of the respective input and output sides of said transistors, and the voltage and current level of said common power output. The system is part of an interconnection scheme in which all but one of the power sources is connected to a single load transfer unit, enabling the survival of at least a single power source with the failure of one of the load transfer units.

Electric power distribution and load transfer system

NASA Technical Reports Server (NTRS)

Bradford, Michael P. (Inventor); Parkinson, Gerald W. (Inventor); Grant, Ross M. (Inventor)

1989-01-01

A power distribution system includes a plurality of power sources and load transfer units including transistors and diodes connected in series and leading to a common power output, each of the transistors being controller switchable subject to voltage levels of the respective input and output sides of said transistors, and the voltage and current level of said common power output. The system is part of an interconnection scheme in which all but one of the power sources is connected to a single load transfer unit, enabling the survival of at least a single power source with the failure of one of the load transfer units.

SDR input power estimation algorithms

NASA Astrophysics Data System (ADS)

Briones, J. C.; Nappier, J. M.

The General Dynamics (GD) S-Band software defined radio (SDR) in the Space Communications and Navigation (SCAN) Testbed on the International Space Station (ISS) provides experimenters an opportunity to develop and demonstrate experimental waveforms in space. The SDR has an analog and a digital automatic gain control (AGC) and the response of the AGCs to changes in SDR input power and temperature was characterized prior to the launch and installation of the SCAN Testbed on the ISS. The AGCs were used to estimate the SDR input power and SNR of the received signal and the characterization results showed a nonlinear response to SDR input power and temperature. In order to estimate the SDR input from the AGCs, three algorithms were developed and implemented on the ground software of the SCAN Testbed. The algorithms include a linear straight line estimator, which used the digital AGC and the temperature to estimate the SDR input power over a narrower section of the SDR input power range. There is a linear adaptive filter algorithm that uses both AGCs and the temperature to estimate the SDR input power over a wide input power range. Finally, an algorithm that uses neural networks was designed to estimate the input power over a wide range. This paper describes the algorithms in detail and their associated performance in estimating the SDR input power.

SDR Input Power Estimation Algorithms

NASA Technical Reports Server (NTRS)

Nappier, Jennifer M.; Briones, Janette C.

2013-01-01

The General Dynamics (GD) S-Band software defined radio (SDR) in the Space Communications and Navigation (SCAN) Testbed on the International Space Station (ISS) provides experimenters an opportunity to develop and demonstrate experimental waveforms in space. The SDR has an analog and a digital automatic gain control (AGC) and the response of the AGCs to changes in SDR input power and temperature was characterized prior to the launch and installation of the SCAN Testbed on the ISS. The AGCs were used to estimate the SDR input power and SNR of the received signal and the characterization results showed a nonlinear response to SDR input power and temperature. In order to estimate the SDR input from the AGCs, three algorithms were developed and implemented on the ground software of the SCAN Testbed. The algorithms include a linear straight line estimator, which used the digital AGC and the temperature to estimate the SDR input power over a narrower section of the SDR input power range. There is a linear adaptive filter algorithm that uses both AGCs and the temperature to estimate the SDR input power over a wide input power range. Finally, an algorithm that uses neural networks was designed to estimate the input power over a wide range. This paper describes the algorithms in detail and their associated performance in estimating the SDR input power.

Modeling and simulation of a hybrid ship power system

NASA Astrophysics Data System (ADS)

Doktorcik, Christopher J.

2011-12-01

Optimizing the performance of naval ship power systems requires integrated design and coordination of the respective subsystems (sources, converters, and loads). A significant challenge in the system-level integration is solving the Power Management Control Problem (PMCP). The PMCP entails deciding on subsystem power usages for achieving a trade-off between the error in tracking a desired position/velocity profile, minimizing fuel consumption, and ensuring stable system operation, while at the same time meeting performance limitations of each subsystem. As such, the PMCP naturally arises at a supervisory level of a ship's operation. In this research, several critical steps toward the solution of the PMCP for surface ships have been undertaken. First, new behavioral models have been developed for gas turbine engines, wound rotor synchronous machines, DC super-capacitors, induction machines, and ship propulsion systems. Conventional models describe system inputs and outputs in terms of physical variables such as voltage, current, torque, and force. In contrast, the behavioral models developed herein express system inputs and outputs in terms of power whenever possible. Additionally, the models have been configured to form a hybrid system-level power model (HSPM) of a proposed ship electrical architecture. Lastly, several simulation studies have been completed to expose the capabilities and limitations of the HSPM.

Compact millijoule diode-seeded two-stage fiber master oscillator power amplifier using a multipass and forward pumping scheme.

PubMed

Lai, Po-Yen; Chang, Chun-Lin; Huang, Sheng-Lung; Chen, Shih-Hung

2018-05-01

The multipass scheme for a diode-seeded fiber master oscillator power amplifier with a nanojoule-to-millijoule output energy level at a repetition rate of <100  kHz is numerically analyzed for comparison to an experimental benchmark. For a 6/125 single-mode preamplifier with a small input energy (<1  nJ), there is a significant improvement in the output energy from 0.7% to 80% and 95% of the maximum extractable energy using the double-pass and four-pass schemes, respectively. For a 30/250 large-mode-area power amplifier using the double-pass and forward pumping scheme, the required input energy is decreased from 100 μJ to 18 μJ for millijoule energy extraction with accompanying Stokes waves of less than 10% of the total energy. The system based on the full master oscillator power amplifier configuration with an output energy exceeding millijoule level can be optimally simplified to two stages for commercialization.

Research on energy conversion mechanism of rotodynamic pump and design of non-overload centrifugal pump

NASA Astrophysics Data System (ADS)

Zhang, X. L.; Hu, S. B.; Shen, Z. Z.; Wu, S. P.; Li, K.

2016-05-01

In this paper, an attempt has been made for the calculation of an expression for the intrinsic law of input power which has not yet been given by current theory of Rotodynamic pump. By adequate recognition of the characteristics of non-inertial system within the rotating impeller, it is concluded that the input power consists of two power components, the first power component, whose magnitude increases with the increase of the flow rate, corresponds to radial velocity component, and the second power component, whose magnitude decreases with the increase of the flow rate, corresponds to tangential velocity component, therefore, the law of rise, basic levelness and drop of input power curves of centrifugal pump, mixed-flow pump and axial-flow pump can be explained reasonably. Through further analysis, the main ways for realizing non-overload of centrifugal pump are obtained, and its equivalent design factor is found out, the factor correlates with the outlet angle of leading face and back face of the blade, wrap angle, number of blades, outlet width, area ratio, and the ratio of operating flow rate to specified flow rate and so on. These are verified with actual example.

A programmable power processor for high power space applications

NASA Technical Reports Server (NTRS)

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

1982-01-01

A Programmable Power Processor (P3) has been developed for application in future large space power systems. The P3 is capable of operation over a wide range of input voltage (26 to 375 Vdc) and output voltage (24 to 180 Vdc). The peak output power capability is 18 kW (180 V at 100 A). The output characteristics of the P3 can be programmed to any voltage and/or current level within the limits of the processor and may be controlled as a function of internal or external parameters. Seven breadboard P3s and one 'flight-type' engineering model P3 have been built and tested both individually and in electrical power systems. The programmable feature allows the P3 to be used in a variety of applications by changing the output characteristics. Test results, including efficiency at various input/output combinations, transient response, and output impedance, are presented.

Fume generation and content of total chromium and hexavalent chromium in flux-cored arc welding.

PubMed

Yoon, Chung Sik; Paik, Nam Won; Kim, Jeong Han

2003-11-01

This study was performed to investigate the fume generation rates (FGRs) and the concentrations of total chromium and hexavalent chromium when stainless steel was welded using flux-cored arc welding (FCAW) with CO2 gas. FGRs and concentrations of total chromium and hexavalent chromium were quantified using a method recommended by the American Welding Society, inductively coupled plasma-atomic emission spectroscopy (NIOSH Method 7300) and ion chromatography (modified NIOSH Method 7604), respectively. The amount of total fume generated was significantly related to the level of input power. The ranges of FGR were 189-344, 389-698 and 682-1157 mg/min at low, optimal and high input power, respectively. It was found that the FGRs increased with input power by an exponent of 1.19, and increased with current by an exponent of 1.75. The ranges of total chromium fume generation rate (FGRCr) were 3.83-8.27, 12.75-37.25 and 38.79-76.46 mg/min at low, optimal and high input power, respectively. The ranges of hexavalent chromium fume generation rate (FGRCr6+) were 0.46-2.89, 0.76-6.28 and 1.70-11.21 mg/min at low, optimal and high input power, respectively. Thus, hexavalent chromium, which is known to be a carcinogen, generated 1.9 (1.0-2.7) times and 3.7 (2.4-5.0) times as the input power increased from low to optimal and low to high, respectively. As a function of input power, the concentration of total chromium in the fume increased from 1.57-2.65 to 5.45-8.13% while the concentration of hexavalent chromium ranged from 0.15 to 1.08%. The soluble fraction of hexavalent chromium produced by FCAW was approximately 80-90% of total hexavalent chromium. The concentration of total chromium and the solubility of hexavalent chromium were similar to those reported from other studies of shielded metal arc welding fumes, and the concentration of hexavalent chromium was similar to that obtained for metal inert gas-welding fumes.

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.

High-Power Hall Thruster Technology Evaluated for Primary Propulsion Applications

NASA Technical Reports Server (NTRS)

Manzella, David H.; Jankovsky, Robert S.; Hofer, Richard R.

2003-01-01

High-power electric propulsion systems have been shown to be enabling for a number of NASA concepts, including piloted missions to Mars and Earth-orbiting solar electric power generation for terrestrial use (refs. 1 and 2). These types of missions require moderate transfer times and sizable thrust levels, resulting in an optimized propulsion system with greater specific impulse than conventional chemical systems and greater thrust than ion thruster systems. Hall thruster technology will offer a favorable combination of performance, reliability, and lifetime for such applications if input power can be scaled by more than an order of magnitude from the kilowatt level of the current state-of-the-art systems. As a result, the NASA Glenn Research Center conducted strategic technology research and development into high-power Hall thruster technology. During program year 2002, an in-house fabricated thruster, designated the NASA-457M, was experimentally evaluated at input powers up to 72 kW. These tests demonstrated the efficacy of scaling Hall thrusters to high power suitable for a range of future missions. Thrust up to nearly 3 N was measured. Discharge specific impulses ranged from 1750 to 3250 sec, with discharge efficiencies between 46 and 65 percent. This thruster is the highest power, highest thrust Hall thruster ever tested.

High Power Light Gas Helicon Plasma Source for VASIMR

NASA Technical Reports Server (NTRS)

Squire, Jared P.; Chang-Diaz, Franklin R.; Glover, Timothy W.; Jacobson, Verlin T.; Baity, F. Wally; Carter, Mark D.; Goulding, Richard H.

2004-01-01

In the Advanced Space Propulsion Laboratory (ASPL) helicon experiment (VX-10) we have measured a plasma flux to input gas rate ratio near 100% for both helium and deuterium at power levels up to 10 kW. Recent results at Oak Ridge National Laboratory (ORNL) show enhanced efficiency operation with a high power density, over 5 kW in a 5 cm diameter tube. Our helicon is presently 9 cm in diameter and operates up to 10 kW of input power. The data here uses a Boswell double-saddle antenna design with a magnetic cusp just upstream of the antenna. Similar to ORNL, for deuterium at near 10 kW, we find an enhanced performance of operation at magnetic fields above the lower hybrid matching condition.

Progress in Low-Power Digital Microwave Radiometer Technologies

NASA Technical Reports Server (NTRS)

Piepmeier, Jeffrey R.; Kim, Edward J.

2004-01-01

Three component technologies were combined into a digital correlation microwave radiometer. The radiometer comprises a dual-channel X-band superheterodyne receiver, low-power high-speed cross-correlator (HSCC), three-level ADCs, and a correlated noise source (CNS). The HSCC dissipates 10 mW and operates at 500 MHz clock speed. The ADCs are implemented using ECL components and dissipate more power than desired. Thus, a low-power ADC development is underway. The new ADCs arc predicted to dissipated less than 200 mW and operate at 1 GSps with 1.5 GHz of input bandwidth. The CNS provides different input correlation values for calibration of the radiometer. The correlation channel had a null offset of 0.0008. Test results indicate that the correlation channel can be calibrated with 0.09% error in gain.

Framework for Mapping of Receiver Interference Tolerance Masks to Tolerable Effective Isotropic Radiated Power Levels : GPS ABC Workshop V RTCA Washington, DC October 14, 2016.

DOT National Transportation Integrated Search

2016-10-14

Outline : : Interference Tolerance Mask (ITM) to Effective Isotropic Radiated Power (IRP) for the particular case of a single transmitter : : ITM() to IRP() for the general case of multiple transmitters : : Input parameters needed to solv...

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

Economic Impacts of Wind Turbine Development in U.S. Counties

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

J., Brown; B., Hoen; E., Lantz

2011-07-25

The objective is to address the research question using post-project construction, county-level data, and econometric evaluation methods. Wind energy is expanding rapidly in the United States: Over the last 4 years, wind power has contributed approximately 35 percent of all new electric power capacity. Wind power plants are often developed in rural areas where local economic development impacts from the installation are projected, including land lease and property tax payments and employment growth during plant construction and operation. Wind energy represented 2.3 percent of the U.S. electricity supply in 2010, but studies show that penetrations of at least 20 percentmore » are feasible. Several studies have used input-output models to predict direct, indirect, and induced economic development impacts. These analyses have often been completed prior to project construction. Available studies have not yet investigated the economic development impacts of wind development at the county level using post-construction econometric evaluation methods. Analysis of county-level impacts is limited. However, previous county-level analyses have estimated operation-period employment at 0.2 to 0.6 jobs per megawatt (MW) of power installed and earnings at $9,000/MW to $50,000/MW. We find statistically significant evidence of positive impacts of wind development on county-level per capita income from the OLS and spatial lag models when they are applied to the full set of wind and non-wind counties. The total impact on annual per capita income of wind turbine development (measured in MW per capita) in the spatial lag model was $21,604 per MW. This estimate is within the range of values estimated in the literature using input-output models. OLS results for the wind-only counties and matched samples are similar in magnitude, but are not statistically significant at the 10-percent level. We find a statistically significant impact of wind development on employment in the OLS analysis for wind counties only, but not in the other models. Our estimates of employment impacts are not precise enough to assess the validity of employment impacts from input-output models applied in advance of wind energy project construction. The analysis provides empirical evidence of positive income effects at the county level from cumulative wind turbine development, consistent with the range of impacts estimated using input-output models. Employment impacts are less clear.« less

Logarithmic and power law input-output relations in sensory systems with fold-change detection.

PubMed

Adler, Miri; Mayo, Avi; Alon, Uri

2014-08-01

Two central biophysical laws describe sensory responses to input signals. One is a logarithmic relationship between input and output, and the other is a power law relationship. These laws are sometimes called the Weber-Fechner law and the Stevens power law, respectively. The two laws are found in a wide variety of human sensory systems including hearing, vision, taste, and weight perception; they also occur in the responses of cells to stimuli. However the mechanistic origin of these laws is not fully understood. To address this, we consider a class of biological circuits exhibiting a property called fold-change detection (FCD). In these circuits the response dynamics depend only on the relative change in input signal and not its absolute level, a property which applies to many physiological and cellular sensory systems. We show analytically that by changing a single parameter in the FCD circuits, both logarithmic and power-law relationships emerge; these laws are modified versions of the Weber-Fechner and Stevens laws. The parameter that determines which law is found is the steepness (effective Hill coefficient) of the effect of the internal variable on the output. This finding applies to major circuit architectures found in biological systems, including the incoherent feed-forward loop and nonlinear integral feedback loops. Therefore, if one measures the response to different fold changes in input signal and observes a logarithmic or power law, the present theory can be used to rule out certain FCD mechanisms, and to predict their cooperativity parameter. We demonstrate this approach using data from eukaryotic chemotaxis signaling.

Dependence of the bit error rate on the signal power and length of a single-channel coherent single-span communication line (100 Gbit s{sup -1}) with polarisation division multiplexing

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

Gurkin, N V; Konyshev, V A; Novikov, A G

2015-01-31

We have studied experimentally and using numerical simulations and a phenomenological analytical model the dependences of the bit error rate (BER) on the signal power and length of a coherent single-span communication line with transponders employing polarisation division multiplexing and four-level phase modulation (100 Gbit s{sup -1} DP-QPSK format). In comparing the data of the experiment, numerical simulations and theoretical analysis, we have found two optimal powers: the power at which the BER is minimal and the power at which the fade margin in the line is maximal. We have derived and analysed the dependences of the BER on themore » optical signal power at the fibre line input and the dependence of the admissible input signal power range for implementation of the communication lines with a length from 30 – 50 km up to a maximum length of 250 km. (optical transmission of information)« less

A low-power inverter-based CMOS level-crossing analog-to-digital converter for low-frequency biosignal sensing

NASA Astrophysics Data System (ADS)

Tanaka, Suiki; Niitsu, Kiichi; Nakazato, Kazuo

2016-03-01

Low-power analog-to-digital conversion is a key technique for power-limited biomedical applications such as power-limited continuous glucose monitoring. However, a conventional uniform-sampling analog-to-digital converter (ADC) is not suitable for nonuniform biosignals. A level-crossing ADC (LC-ADC) is a promising candidate for low-power biosignal processing because of its event-driven properties. The LC-ADC acquires data by level-crossing sampling. When an input signal crosses the threshold level, the LC-ADC samples the signal. The conventional LC-ADC employs a power-hungry comparator. In this paper, we present a low-power inverter-based LC-ADC. By adjusting the threshold level of the inverter, it can be used as a threshold-fixed window comparator. By using the inverter as an alternative to a comparator, power consumption can be markedly reduced. As a result, the total power consumption is successfully reduced by 90% of that of previous LC-ADC. The inverter-based LC-ADC was found to be very suitable for use in power-limited biomedical devices.

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.

Nonlinear distortion analysis for single heterojunction GaAs HEMT with frequency and temperature

NASA Astrophysics Data System (ADS)

Alim, Mohammad A.; Ali, Mayahsa M.; Rezazadeh, Ali A.

2018-07-01

Nonlinearity analysis using two-tone intermodulation distortion (IMD) technique for 0.5 μm gate-length AlGaAs/GaAs based high electron mobility transistor have been investigated based on biasing conditions, input power, frequency and temperature. The outcomes indicate a significant modification on the output IMD power and as well as the minimum distortion level. The input IMD power effects the output current and subsequently the threshold voltage reduces, resulting to an increment in the output IMD power. Both frequency and temperature reduces the magnitude of the output IMDs. In addition, the threshold voltage response with temperature alters the notch point of the nonlinear output IMD’s accordingly. The aforementioned investigation will help the circuit designers to evaluate the best biasing option in terms of minimum distortion, maximum gain for future design optimizations.

Performance Testing of a Prototypic Annular Linear Induction Pump for Fission Surface Power

NASA Technical Reports Server (NTRS)

Polzin, K. A.; Pearson, J. B.; Schoenfeld, M. P.; Webster, K.; Houts, M. G.; Godfroy, T. J.; Bossard, J. A.

2010-01-01

Results of performance testing of an annular linear induction pump are presented. The pump electromagnetically pumps liquid metal (NaK) through a circuit specially designed to allow for quantification of the performance. Testing was conducted over a range of conditions, including frequencies of 33, 36, 39, and 60 Hz, liquid metal temperatures from 25 to 525 C, and input voltages from 5 to 120 V. Pump performance spanned a range of flow rates from roughly 0.16 to 5.7 L/s (2.5 to 90 gpm), and pressure head <1 to 90 kPa (<0.145 to 13 psi). The maximum efficiency measured during testing was slightly greater than 6%. The efficiency was fairly insensitive to input frequency from 33 to 39 Hz, and was markedly lower at 60 Hz. In addition, the efficiency decreased as the NaK temperature was raised. While the pump was powered, the fluid responded immediately to changes in the input power level, but when power was removed altogether, there was a brief slow-down period before the fluid would come to rest. The performance of the pump operating on a variable frequency drive providing 60 Hz power compared favorably with the same pump operating on 60 Hz power drawn directly from the electrical grid.

RF rectifiers for EM power harvesting in a Deep Brain Stimulating device.

PubMed

Hosain, Md Kamal; Kouzani, Abbas Z; Tye, Susannah; Kaynak, Akif; Berk, Michael

2015-03-01

A passive deep brain stimulation (DBS) device can be equipped with a rectenna, consisting of an antenna and a rectifier, to harvest energy from electromagnetic fields for its operation. This paper presents optimization of radio frequency rectifier circuits for wireless energy harvesting in a passive head-mountable DBS device. The aim is to achieve a compact size, high conversion efficiency, and high output voltage rectifier. Four different rectifiers based on the Delon doubler, Greinacher voltage tripler, Delon voltage quadrupler, and 2-stage charge pumped architectures are designed, simulated, fabricated, and evaluated. The design and simulation are conducted using Agilent Genesys at operating frequency of 915 MHz. A dielectric substrate of FR-4 with thickness of 1.6 mm, and surface mount devices (SMD) components are used to fabricate the designed rectifiers. The performance of the fabricated rectifiers is evaluated using a 915 MHz radio frequency (RF) energy source. The maximum measured conversion efficiency of the Delon doubler, Greinacher tripler, Delon quadrupler, and 2-stage charge pumped rectifiers are 78, 75, 73, and 76 % at -5 dBm input power and for load resistances of 5-15 kΩ. The conversion efficiency of the rectifiers decreases significantly with the increase in the input power level. The Delon doubler rectifier provides the highest efficiency at both -5 and 5 dBm input power levels, whereas the Delon quadrupler rectifier gives the lowest efficiency for the same inputs. By considering both efficiency and DC output voltage, the charge pump rectifier outperforms the other three rectifiers. Accordingly, the optimised 2-stage charge pumped rectifier is used together with an antenna to harvest energy in our DBS device.

Power inverter with optical isolation

DOEpatents

Duncan, Paul G.; Schroeder, John Alan

2005-12-06

An optically isolated power electronic power conversion circuit that includes an input electrical power source, a heat pipe, a power electronic switch or plurality of interconnected power electronic switches, a mechanism for connecting the switch to the input power source, a mechanism for connecting comprising an interconnecting cable and/or bus bar or plurality of interconnecting cables and/or input bus bars, an optically isolated drive circuit connected to the switch, a heat sink assembly upon which the power electronic switch or switches is mounted, an output load, a mechanism for connecting the switch to the output load, the mechanism for connecting including an interconnecting cable and/or bus bar or plurality of interconnecting cables and/or output bus bars, at least one a fiber optic temperature sensor mounted on the heat sink assembly, at least one fiber optic current sensor mounted on the load interconnection cable and/or output bus bar, at least one fiber optic voltage sensor mounted on the load interconnection cable and/or output bus bar, at least one fiber optic current sensor mounted on the input power interconnection cable and/or input bus bar, and at least one fiber optic voltage sensor mounted on the input power interconnection cable and/or input bus bar.

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

Weimar, Mark R.; Daly, Don S.; Wood, Thomas W.

Both nuclear power and nuclear weapons programs should have (related) economic signatures which are detectible at some scale. We evaluated this premise in a series of studies using national economic input/output (IO) data. Statistical discrimination models using economic IO tables predict with a high probability whether a country with an unknown predilection for nuclear weapons proliferation is in fact engaged in nuclear power development or nuclear weapons proliferation. We analyzed 93 IO tables, spanning the years 1993 to 2005 for 37 countries that are either members or associates of the Organization for Economic Cooperation and Development (OECD). The 2009 OECDmore » input/output tables featured 48 industrial sectors based on International Standard Industrial Classification (ISIC) Revision 3, and described the respective economies in current country-of-origin valued currency. We converted and transformed these reported values to US 2005 dollars using appropriate exchange rates and implicit price deflators, and addressed discrepancies in reported industrial sectors across tables. We then classified countries with Random Forest using either the adjusted or industry-normalized values. Random Forest, a classification tree technique, separates and categorizes countries using a very small, select subset of the 2304 individual cells in the IO table. A nation’s efforts in nuclear power, be it for electricity or nuclear weapons, are an enterprise with a large economic footprint -- an effort so large that it should discernibly perturb coarse country-level economics data such as that found in yearly input-output economic tables. The neoclassical economic input-output model describes a country’s or region’s economy in terms of the requirements of industries to produce the current level of economic output. An IO table row shows the distribution of an industry’s output to the industrial sectors while a table column shows the input required of each industrial sector by a given industry.« less

Dynamics of drive systems for wind energy conversion

NASA Technical Reports Server (NTRS)

Martinez-Sanchez, M.

1978-01-01

Calculations are performed to determine the dynamic effects of mechanical power transmission from the nacelle of a horizontal axis wind machine to the ground or to an intermediate level. It is found that resonances are likely at 2 or 4/REV, but they occur at low power only, and seem easily correctable. Large reductions are found in the harmonic torque inputs to the generator at powers near rated.

System level latchup mitigation for single event and transient radiation effects on electronics

DOEpatents

Kimbrough, J.R.; Colella, N.J.

1997-09-30

A ``blink`` technique, analogous to a person blinking at a flash of bright light, is provided for mitigating the effects of single event current latchup and prompt pulse destructive radiation on a micro-electronic circuit. The system includes event detection circuitry, power dump logic circuitry, and energy limiting measures with autonomous recovery. The event detection circuitry includes ionizing radiation pulse detection means for detecting a pulse of ionizing radiation and for providing at an output terminal thereof a detection signal indicative of the detection of a pulse of ionizing radiation. The current sensing circuitry is coupled to the power bus for determining an occurrence of excess current through the power bus caused by ionizing radiation or by ion-induced destructive latchup of a semiconductor device. The power dump circuitry includes power dump logic circuitry having a first input terminal connected to the output terminal of the ionizing radiation pulse detection circuitry and having a second input terminal connected to the output terminal of the current sensing circuitry. The power dump logic circuitry provides an output signal to the input terminal of the circuitry for opening the power bus and the circuitry for shorting the power bus to a ground potential to remove power from the power bus. The energy limiting circuitry with autonomous recovery includes circuitry for opening the power bus and circuitry for shorting the power bus to a ground potential. The circuitry for opening the power bus and circuitry for shorting the power bus to a ground potential includes a series FET and a shunt FET. The invention provides for self-contained sensing for latchup, first removal of power to protect latched components, and autonomous recovery to enable transparent operation of other system elements. 18 figs.

System level latchup mitigation for single event and transient radiation effects on electronics

DOEpatents

Kimbrough, Joseph Robert; Colella, Nicholas John

1997-01-01

A "blink" technique, analogous to a person blinking at a flash of bright light, is provided for mitigating the effects of single event current latchup and prompt pulse destructive radiation on a micro-electronic circuit. The system includes event detection circuitry, power dump logic circuitry, and energy limiting measures with autonomous recovery. The event detection circuitry includes ionizing radiation pulse detection means for detecting a pulse of ionizing radiation and for providing at an output terminal thereof a detection signal indicative of the detection of a pulse of ionizing radiation. The current sensing circuitry is coupled to the power bus for determining an occurrence of excess current through the power bus caused by ionizing radiation or by ion-induced destructive latchup of a semiconductor device. The power dump circuitry includes power dump logic circuitry having a first input terminal connected to the output terminal of the ionizing radiation pulse detection circuitry and having a second input terminal connected to the output terminal of the current sensing circuitry. The power dump logic circuitry provides an output signal to the input terminal of the circuitry for opening the power bus and the circuitry for shorting the power bus to a ground potential to remove power from the power bus. The energy limiting circuitry with autonomous recovery includes circuitry for opening the power bus and circuitry for shorting the power bus to a ground potential. The circuitry for opening the power bus and circuitry for shorting the power bus to a ground potential includes a series FET and a shunt FET. The invention provides for self-contained sensing for latchup, first removal of power to protect latched components, and autonomous recovery to enable transparent operation of other system elements.

Traction Drives for Zero Stick-Slip Robots, and Reaction Free, Momentum Balanced Systems

NASA Technical Reports Server (NTRS)

Anderson, William J.; Shipitalo, William; Newman, Wyatt

1995-01-01

Two differential (dual input, single output) drives (a roller-gear and a pure roller), and a momentum balanced (single input, dual output) drive (pure roller ) were designed, fabricated, and tested. The differential drives are each rated at 295 rad/sec (2800 rpm) input speed, 450 N-m (4,000 in-lbf) output torque. The momentum balanced drive is rated at 302 rad/sec (2880 rpm) input speed, and dual output torques of 434N-m (3840 in-lbf). The Dual Input Differential Roller-Gear Drive (DC-700) has a planetary roller-gear system with a reduction ratio (one input driving the output with the second input fixed) of 29.23: 1. The Dual Input Differential Roller Drive (DC-500) has a planetary roller system with a reduction ratio of approximately 24:1. Each of the differential drives features dual roller-gear or roller arrangements consisting of a sun, four first row planets, four second row planets, and a ring. The Momentum Balanced (Grounded Ring) Drive (DC-400) has a planetary roller system with a reduction ratio of 24:1 with both outputs counterrotating at equal speed. Its single roller cluster consists of a sun, five first and five second row planets, a roller cage or spider and a ring. Outputs are taken from both the roller cage and the ring which counterrotate. Test results reported for all three drives include angular and torque ripple (linearity and cogging), viscous and Coulomb friction, and forward and reverse power efficiency. Of the two differential drives, the Differential Roller Drive had better linearity and less cogging than did the Differential Roller-Gear Drive, but it had higher friction and lower efficiency (particularly at low power throughput levels). Use of full preloading rather than a variable preload system in the Differential Roller Drive assessed a heavy penalty in part load efficiency. Maximum measured efficiency (ratio of power out to power in) was 95% for the Differential Roller-Gear Drive and 86% for the Differential Roller Drive. The Momentum Balanced (Grounded Ring) Drive performed as expected kinematically. Reduction r-atios to the two counterrotating outputs (design nominal=24:1) were measured to be 23.98:1 and 24.12:1 at zero load.. At 25ONm (2200 in-lbf) output torque the ratio changed 2% due to roller creep. This drive was the smoothest of all three as determined from linearity and cogging tests, and maximum measured efficiency (ratio of power out to power in) was 95%. The disadvantages of full preloading as comvared to variable preload were apparent in this drive as in the Differential Roller Drive. Efficiencies at part load were low, but improved dramatically with increases in torque. These were consistent with friction measurements which indicated losses primarily from Coulomb friction. The initial preload level setting was low so roller slip was encountered at higher torques during testing.

THERMOCOUPLE VACUUM GAUGE

DOEpatents

Price, G.W.

1954-08-01

A protector device is described for use in controlling the pressure within a cyclotron. In particular, an electrical circuit functions to actuate a vacuum pump when a predetermined low pressure is reached and disconnect the pump when the pressure increases abcve a certain value. The principal feature of the control circuit lies in the use of a voltage divider network at the input to a relay control tube comprising two parallel, adjustable resistances wherein one resistor is switched into the circuit when the relay connects the pump to a power source. With this arrangement the relay is energized at one input level received from a sensing element within the cyclotron chamber and is de-energized when a second input level, representing the higher pressure limit, is reached.

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.

Test Results of Selected Commercial DC/DC Converters under Cryogenic Temperatures - A Digest

NASA Technical Reports Server (NTRS)

Patterson, Richard; Hammoud, Ahmad

2010-01-01

DC/DC converters are widely used in space power systems in the areas of power management and distribution, signal conditioning, and motor control. Design of DC/DC converters to survive cryogenic temperatures will improve the power system performance, simplify design, and reduce development and launch costs. In this work, the performance of nine COTS modular, low-tomedium power DC/DC converters was investigated under cryogenic temperatures. The converters were evaluated in terms of their output regulation, efficiency, and input and output currents. At a given temperature, these properties were obtained at various input voltages and at different load levels. A summary on the performance of the tested converters was given. More comprehensive testing and in-depth analysis of performance under long-term exposure to extreme temperatures are deemed necessary to establish the suitability of these and other devices for use in the harsh environment of space exploration missions.

The advanced LIGO input optics

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

Mueller, Chris L., E-mail: cmueller@phys.ufl.edu; Arain, Muzammil A.; Ciani, Giacomo

The advanced LIGO gravitational wave detectors are nearing their design sensitivity and should begin taking meaningful astrophysical data in the fall of 2015. These resonant optical interferometers will have unprecedented sensitivity to the strains caused by passing gravitational waves. The input optics play a significant part in allowing these devices to reach such sensitivities. Residing between the pre-stabilized laser and the main interferometer, the input optics subsystem is tasked with preparing the laser beam for interferometry at the sub-attometer level while operating at continuous wave input power levels ranging from 100 mW to 150 W. These extreme operating conditions requiredmore » every major component to be custom designed. These designs draw heavily on the experience and understanding gained during the operation of Initial LIGO and Enhanced LIGO. In this article, we report on how the components of the input optics were designed to meet their stringent requirements and present measurements showing how well they have lived up to their design.« less

Dynamic analysis of a buckled asymmetric piezoelectric beam for energy harvesting

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

Van Blarigan, Louis, E-mail: louis01@umail.ucsb.edu; Moehlis, Jeff

2016-03-15

A model of a buckled beam energy harvester is analyzed to determine the phenomena behind the transition between high and low power output levels. It is shown that the presence of a chaotic attractor is a sufficient condition to predict high power output, though there are relatively small areas where high output is achieved without a chaotic attractor. The chaotic attractor appears as a product of a period doubling cascade or a boundary crisis. Bifurcation diagrams provide insight into the development of the chaotic region as the input power level is varied, as well as the intermixed periodic windows.

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

Experimental Results From a 2kW Brayton Power Conversion Unit

NASA Technical Reports Server (NTRS)

Hervol, David; Mason, Lee; Birchenough, Arthur

2003-01-01

This paper presents experimental test results from operation of a 2 kWe Brayton power conversion unit. The Brayton converter was developed for a solar dynamic power system flight experiment planned for the Mir Space Station in 1997. The flight experiment was cancelled, but the converter was tested at Glenn Research Center as part of the Solar Dynamic Ground Test Demonstration system which included a solar concentrator, heat receiver, and space radiator. In preparation for the current testing, the heat receiver was removed and replaced with an electrical resistance heater, simulating the thermal input of a steady-state nuclear source. The converter was operated over a full range of thermal input power levels and rotor speeds to generate an overall performance map. The converter unit will serve as the centerpiece of a Nuclear Electric Propulsion Testbed at Glenn. Future potential uses for the Testbed include high voltage electrical controller development, integrated electric thruster testing and advanced radiator demonstration testing to help guide high power Brayton technology development for Nuclear Electric Propulsion (NEP).

A Comparative Analysis between GaN-Based Current and Voltage Mode Class-D and E PAs for Communications

DTIC Science & Technology

2017-03-01

power level (5-10W) transmitters. The designs are analyzed and compared with respect to non-idealities such as bondwire effects and input signal duty...Hence, sub-optimum class- E/inverse class-E designs were implemented in this work and compared with respect to reduced duty cycle performance...inverse class E PA achieves 61.5% efficiency for medium power levels (37.7dBm) at 880MHz. The three designed PAs have been compared with respect to

Test Results from a Direct Drive Gas Reactor Simulator Coupled to a Brayton Power Conversion Unit

NASA Technical Reports Server (NTRS)

Hervol, David S.; Briggs, Maxwell H.; Owen, Albert K.; Bragg-Sitton, Shannon M.; Godfroy, Thomas J.

2010-01-01

Component level testing of power conversion units proposed for use in fission surface power systems has typically been done using relatively simple electric heaters for thermal input. These heaters do not adequately represent the geometry or response of proposed reactors. As testing of fission surface power systems transitions from the component level to the system level it becomes necessary to more accurately replicate these reactors using reactor simulators. The Direct Drive Gas-Brayton Power Conversion Unit test activity at the NASA Glenn Research Center integrates a reactor simulator with an existing Brayton test rig. The response of the reactor simulator to a change in Brayton shaft speed is shown as well as the response of the Brayton to an insertion of reactivity, corresponding to a drum reconfiguration. The lessons learned from these tests can be used to improve the design of future reactor simulators which can be used in system level fission surface power tests.

Characterization of the electrical output of flat-plate photovoltaic arrays

NASA Technical Reports Server (NTRS)

Gonzalez, C. C.; Hill, G. M.; Ross, R. G., Jr.

1982-01-01

The electric output of flat-plate photovoltaic arrays changes constantly, due primarily to changes in cell temperature and irradiance level. As a result, array loads such as direct-current to alternating-current power conditioners must be able to accommodate widely varying input levels, while maintaining operation at or near the array maximum power point.The results of an extensive computer simulation study that was used to define the parameters necessary for the systematic design of array/power-conditioner interfaces are presented as normalized ratios of power-conditioner parameters to array parameters, to make the results universally applicable to a wide variety of system sizes, sites, and operating modes. The advantages of maximum power tracking and a technique for computing average annual power-conditioner efficiency are discussed.

Research on design feasibility of high-power light-weight dc-to-dc converters for space power application

NASA Technical Reports Server (NTRS)

Wilson, T. G.

1980-01-01

The development of 5 kW converters with 100 kHz switching frequencies, consisting of two submodules each capable of 2.5 kW of output power, is discussed. Two semiconductor advances allowed increased power levels. Field effect transistors with ratings of 11 A and 400 V were operated in parallel to provide a converter output power of approximately 2000 W. Secondly, bipolar power switching transistor was operated in conjunction with a turn-off snubber circuit to provide converter output power levels approaching 1000 W. The interrelationships between mass, switching frequency, and efficiency were investigated. Converters were constructed for operation at a maximum output power level of 200 W, and a comparison was made for operation under similar input/output conditions for conversion frequencies of 20 kilohertz and 100 kilohertz. The effects of nondissipative turn-off snubber circuitry were also examined. Finally, a computerized instrumentation system allowing the measurement of pertinent converter operating conditions as well as the recording of converter waveforms is described.

High power density dc/dc converter: Component selection and design

NASA Technical Reports Server (NTRS)

Divan, Deepakraj M.

1989-01-01

Further work pertaining to design considerations for the new high power, high frequency dc/dc converters is discussed. The goal of the project is the development of high power, high power density dc/dc converters at power levels in the multi-kilowatt to megawatt range for aerospace applications. The prototype converter is rated for 50 kW at a switching frequency of 50 kHz, with an input voltage of 200 Vdc and an output of 2000 Vdc. The overall power density must be in the vicinity of 0.2 to 0.3 kg/kW.

Noise behavior of microwave amplifiers operating under nonlinear conditions

NASA Astrophysics Data System (ADS)

Escotte, L.; Gonneau, E.; Chambon, C.; Graffeuil, J.

2005-12-01

B The noise behavior of microwave amplifiers operating under a large-signal condition has been studied in this paper. A Gaussian noise is added to a microwave signal and they are applied at the input of several amplifying devices. Experimental data show a decrease of the output noise spectral density when the power of the microwave signal at the input of the devices increases due to the compression of the amplifiers. A distortion component due to the interaction of the signal and its harmonics with the noise is also demonstrated from a simplified theoretical model. The statistical properties of the signal and the noise have also been investigated in order to verify the Gaussianity of the noise at the output of the nonlinear circuits. We have also observed that the majority of the measured devices show some variations of their additive noise versus the input power level.

Convergence of Cortical and Sensory Driver Inputs on Single Thalamocortical Cells

PubMed Central

Groh, Alexander; Bokor, Hajnalka; Mease, Rebecca A.; Plattner, Viktor M.; Hangya, Balázs; Stroh, Albrecht; Deschenes, Martin; Acsády, László

2014-01-01

Ascending and descending information is relayed through the thalamus via strong, “driver” pathways. According to our current knowledge, different driver pathways are organized in parallel streams and do not interact at the thalamic level. Using an electron microscopic approach combined with optogenetics and in vivo physiology, we examined whether driver inputs arising from different sources can interact at single thalamocortical cells in the rodent somatosensory thalamus (nucleus posterior, POm). Both the anatomical and the physiological data demonstrated that ascending driver inputs from the brainstem and descending driver inputs from cortical layer 5 pyramidal neurons converge and interact on single thalamocortical neurons in POm. Both individual pathways displayed driver properties, but they interacted synergistically in a time-dependent manner and when co-activated, supralinearly increased the output of thalamus. As a consequence, thalamocortical neurons reported the relative timing between sensory events and ongoing cortical activity. We conclude that thalamocortical neurons can receive 2 powerful inputs of different origin, rather than only a single one as previously suggested. This allows thalamocortical neurons to integrate raw sensory information with powerful cortical signals and transfer the integrated activity back to cortical networks. PMID:23825316

An 11 μ w, two-electrode transimpedance biosignal amplifier with active current feedback stabilization.

PubMed

Inan, O T; Kovacs, G T A

2010-04-01

A novel two-electrode biosignal amplifier circuit is demonstrated by using a composite transimpedance amplifier input stage with active current feedback. Micropower, low gain-bandwidth product operational amplifiers can be used, leading to the lowest reported overall power consumption in the literature for a design implemented with off-the-shelf commercial integrated circuits (11 μW). Active current feedback forces the common-mode input voltage to stay within the supply rails, reducing baseline drift and amplifier saturation problems that can be present in two-electrode systems. The bandwidth of the amplifier extends from 0.05-200 Hz and the midband voltage gain (assuming an electrode-to-skin resistance of 100 kΩ) is 48 dB. The measured output noise level is 1.2 mV pp, corresponding to a voltage signal-to-noise ratio approaching 50 dB for a typical electrocardiogram (ECG) level input of 1 mVpp. Recordings were taken from a subject by using the proposed two-electrode circuit and, simultaneously, a three-electrode standard ECG circuit. The residual of the normalized ensemble averages for both measurements was computed, and the power of this residual was 0.54% of the power of the standard ECG measurement output. While this paper primarily focuses on ECG applications, the circuit can also be used for amplifying other biosignals, such as the electroencephalogram.

Impact of Wind Development on County-Level Income and Employment: A Review of Methods and an Empirical Analysis (Fact Sheet)

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

Not Available

2012-09-01

To gain an understanding of the long-term county-level impacts from a large sample of wind power projects and to understand the potential significance of methodological criticisms, the U.S. Department of Agriculture, the Lawrence Berkeley National Laboratory, and NREL recently joined efforts to complete a first-of-its-kind study that quantifies the annual impact on county-level personal income resulting from wind power installations in nearly 130 counties across 12 states. The results of this study, as well as a comparison with the prior county-level estimates generated from input-output models, are summarized here.

System and component design and test of a 10 hp, 18,000 rpm AC dynamometer utilizing a high frequency AC voltage link, part 1

NASA Technical Reports Server (NTRS)

Lipo, Thomas A.; Alan, Irfan

1991-01-01

Hard and soft switching test results conducted with one of the samples of first generation MOS-controlled thyristor (MCTs) and similar test results with several different samples of second generation MCT's are reported. A simple chopper circuit is used to investigate the basic switching characteristics of MCT under hard switching and various types of resonant circuits are used to determine soft switching characteristics of MCT under both zero voltage and zero current switching. Next, operation principles of a pulse density modulated converter (PDMC) for three phase (3F) to 3F two-step power conversion via parallel resonant high frequency (HF) AC link are reviewed. The details for the selection of power switches and other power components required for the construction of the power circuit for the second generation 3F to 3F converter system are discussed. The problems encountered in the first generation system are considered. Design and performance of the first generation 3F to 3F power converter system and field oriented induction moter drive based upon a 3 kVA, 20 kHz parallel resonant HF AC link are described. Low harmonic current at the input and output, unity power factor operation of input, and bidirectional flow capability of the system are shown via both computer and experimental results. The work completed on the construction and testing of the second generation converter and field oriented induction motor drive based upon specifications for a 10 hp squirrel cage dynamometer and a 20 kHz parallel resonant HF AC link is discussed. The induction machine is designed to deliver 10 hp or 7.46 kW when operated as an AC-dynamo with power fed back to the source through the converter. Results presented reveal that the proposed power level requires additional energy storage elements to overcome difficulties with a peak link voltage variation problem that limits reaching to the desired power level. The power level test of the second generation converter after the addition of extra energy storage elements to the HF link are described. The importance of the source voltage level to achieve a better current regulation for the source side PDMC is also briefly discussed. The power levels achieved in the motoring mode of operation show that the proposed power levels achieved in the generating mode of operation can also be easily achieved provided that no mechanical speed limitation were present to drive the induction machine at the proposed power level.

Oxygen-enriched air for MHD power plants

NASA Technical Reports Server (NTRS)

Ebeling, R. W., Jr.; Cutting, J. C.; Burkhart, J. A.

1979-01-01

Cryogenic air-separation process cycle variations and compression schemes are examined. They are designed to minimize net system power required to supply pressurized, oxygen-enriched air to the combustor of an MHD power plant with a coal input of 2000 MWt. Power requirements and capital costs for oxygen production and enriched air compression for enrichment levels from 13 to 50% are determined. The results are presented as curves from which total compression power requirements can be estimated for any desired enrichment level at any delivery pressure. It is found that oxygen enrichment and recuperative heating of MHD combustor air to 1400 F yields near-term power plant efficiencies in excess of 45%. A minimum power compression system requires 167 MW to supply 330 lb of oxygen per second and costs roughly 100 million dollars. Preliminary studies show MHD/steam power plants to be competitive with plants using high-temperature air preheaters burning gas.

Suppression of multipacting in high power RF couplers operating with superconducting cavities

NASA Astrophysics Data System (ADS)

Ostroumov, P. N.; Kazakov, S.; Morris, D.; Larter, T.; Plastun, A. S.; Popielarski, J.; Wei, J.; Xu, T.

2017-06-01

Capacitive input couplers based on a 50 Ω coaxial transmission line are frequently used to transmit RF power to superconducting (SC) resonators operating in CW mode. It is well known that coaxial transmission lines are prone to multipacting phenomenon in a wide range of RF power level and operating frequency. The Facility for Rare Isotope Beams (FRIB) being constructed at Michigan State University includes two types of quarter wave SC resonators (QWR) operating at 80.5 MHz and two types of half wave SC resonators (HWR) operating at 322 MHz. As was reported in ref. [1] a capacitive input coupler used with HWRs was experiencing strong multipacting that resulted in a long conditioning time prior the cavity testing at design levels of accelerating fields. We have developed an insert into 50 Ω coaxial transmission line that provides opportunity to bias the RF coupler antenna and protect the amplifier from the bias potential in the case of breakdown in DC isolation. Two of such devices have been built and are currently used for the off-line testing of 8 HWRs installed in the cryomodule.

Compact waveguide power divider with multiple isolated outputs

DOEpatents

Moeller, Charles P.

1987-01-01

A waveguide power divider (10) for splitting electromagnetic microwave power and directionally coupling the divided power includes an input waveguide (21) and reduced height output waveguides (23) interconnected by axial slots (22) and matched loads (25) and (26) positioned at the unused ends of input and output guides (21) and (23) respectively. The axial slots are of a length such that the wave in the input waveguide (21) is directionally coupled to the output waveguides (23). The widths of input guide (21) and output guides (23) are equal and the width of axial slots (22) is one half of the width of the input guide (21).

Crops Models for Varying Environmental Conditions

NASA Technical Reports Server (NTRS)

Jones, Harry; Cavazzoni, James; Keas, Paul

2001-01-01

New variable environment Modified Energy Cascade (MEC) crop models were developed for all the Advanced Life Support (ALS) candidate crops and implemented in SIMULINK. The MEC models are based on the Volk, Bugbee, and Wheeler Energy Cascade (EC) model and are derived from more recent Top-Level Energy Cascade (TLEC) models. The MEC models simulate crop plant responses to day-to-day changes in photosynthetic photon flux, photoperiod, carbon dioxide level, temperature, and relative humidity. The original EC model allows changes in light energy but uses a less accurate linear approximation. The simulation outputs of the new MEC models for constant nominal environmental conditions are very similar to those of earlier EC models that use parameters produced by the TLEC models. There are a few differences. The new MEC models allow setting the time for seed emergence, have realistic exponential canopy growth, and have corrected harvest dates for potato and tomato. The new MEC models indicate that the maximum edible biomass per meter squared per day is produced at the maximum allowed carbon dioxide level, the nominal temperatures, and the maximum light input. Reducing the carbon dioxide level from the maximum to the minimum allowed in the model reduces crop production significantly. Increasing temperature decreases production more than it decreases the time to harvest, so productivity in edible biomass per meter squared per day is greater at nominal than maximum temperatures, The productivity in edible biomass per meter squared per day is greatest at the maximum light energy input allowed in the model, but the edible biomass produced per light energy input unit is lower than at nominal light levels. Reducing light levels increases light and power use efficiency. The MEC models suggest we can adjust the light energy day-to- day to accommodate power shortages or Lise excess power while monitoring and controlling edible biomass production.

Statistical properties of radiation power levels from a high-gain free-electron laser at and beyond saturation

NASA Astrophysics Data System (ADS)

Schroeder, C. B.; Fawley, W. M.; Esarey, E.

2003-07-01

We investigate the statistical properties (e.g., shot-to-shot power fluctuations) of the radiation from a high-gain free-electron laser (FEL) operating in the nonlinear regime. We consider the case of an FEL amplifier reaching saturation whose shot-to-shot fluctuations in input radiation power follow a gamma distribution. We analyze the corresponding output power fluctuations at and beyond saturation, including beam energy spread effects, and find that there are well-characterized values of undulator length for which the fluctuations reach a minimum.

Thermal effects in the Input Optics of the Enhanced Laser Interferometer Gravitational-Wave Observatory interferometers.

PubMed

Dooley, Katherine L; Arain, Muzammil A; Feldbaum, David; Frolov, Valery V; Heintze, Matthew; Hoak, Daniel; Khazanov, Efim A; Lucianetti, Antonio; Martin, Rodica M; Mueller, Guido; Palashov, Oleg; Quetschke, Volker; Reitze, David H; Savage, R L; Tanner, D B; Williams, Luke F; Wu, Wan

2012-03-01

We present the design and performance of the LIGO Input Optics subsystem as implemented for the sixth science run of the LIGO interferometers. The Initial LIGO Input Optics experienced thermal side effects when operating with 7 W input power. We designed, built, and implemented improved versions of the Input Optics for Enhanced LIGO, an incremental upgrade to the Initial LIGO interferometers, designed to run with 30 W input power. At four times the power of Initial LIGO, the Enhanced LIGO Input Optics demonstrated improved performance including better optical isolation, less thermal drift, minimal thermal lensing, and higher optical efficiency. The success of the Input Optics design fosters confidence for its ability to perform well in Advanced LIGO.

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.

Photovoltaic power system tests on an 8-kilowatt single-phase line-commutated inverter

NASA Technical Reports Server (NTRS)

Stover, J. B.

1978-01-01

Efficiency and power factor were measured as functions of solar array voltage and current. The effects of input shunt capacitance and series inductance were determined. Tests were conducted from 15 to 75 percent of the 8 kW rated inverter input power. Measured efficiencies ranged from 76 percent to 88 percent at about 50 percent of rated inverter input power. Power factor ranged from 36 percent to 72 percent.

Fast algorithm of low power image reformation for OLED display

NASA Astrophysics Data System (ADS)

Lee, Myungwoo; Kim, Taewhan

2014-04-01

We propose a fast algorithm of low-power image reformation for organic light-emitting diode (OLED) display. The proposed algorithm scales the image histogram in a way to reduce power consumption in OLED display by remapping the gray levels of the pixels in the image based on the fast analysis of the histogram of the input image while maintaining contrast of the image. The key idea is that a large number of gray levels are never used in the images and these gray levels can be effectively exploited to reduce power consumption. On the other hand, to maintain the image contrast the gray level remapping is performed by taking into account the object size in the image to which each gray level is applied, that is, reforming little for the gray levels in the objects of large size. Through experiments with 24 Kodak images, it is shown that our proposed algorithm is able to reduce the power consumption by 10% even with 9% contrast enhancement. Our algorithm runs in a linear time so that it can be applied to moving pictures with high resolution.

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

High Input Voltage, Silicon Carbide Power Processing Unit Performance Demonstration

NASA Technical Reports Server (NTRS)

Bozak, Karin E.; Pinero, Luis R.; Scheidegger, Robert J.; Aulisio, Michael V.; Gonzalez, Marcelo C.; Birchenough, Arthur G.

2015-01-01

A silicon carbide brassboard power processing unit has been developed by the NASA Glenn Research Center in Cleveland, Ohio. The power processing unit operates from two sources - a nominal 300-Volt high voltage input bus and a nominal 28-Volt low voltage input bus. The design of the power processing unit includes four low voltage, low power supplies that provide power to the thruster auxiliary supplies, and two parallel 7.5 kilowatt power supplies that are capable of providing up to 15 kilowatts of total power at 300-Volts to 500-Volts to the thruster discharge supply. Additionally, the unit contains a housekeeping supply, high voltage input filter, low voltage input filter, and master control board, such that the complete brassboard unit is capable of operating a 12.5 kilowatt Hall Effect Thruster. The performance of unit was characterized under both ambient and thermal vacuum test conditions, and the results demonstrate the exceptional performance with full power efficiencies exceeding 97. With a space-qualified silicon carbide or similar high voltage, high efficiency power device, this design could evolve into a flight design for future missions that require high power electric propulsion systems.

Efficient Strategies for Predictive Cell-Level Control of Lithium-Ion Batteries

NASA Astrophysics Data System (ADS)

Xavier, Marcelo A.

This dissertation introduces a set of state-space based model predictive control (MPC) algorithms tailored to a non-zero feedthrough term to account for the ohmic resistance that is inherent to the battery dynamics. MPC is herein applied to the problem of regulating cell-level measures of performance for lithium-ion batteries; the control methodologies are used first to compute a fast charging profile that respects input, output, and state constraints, i.e., input current, terminal voltage, and state of charge for an equivalent circuit model of the battery cell, and extended later to a linearized physics-based reduced-order model. The novelty of this work can summarized as follows: (1) the MPC variants are employed to a physics based reduce-order model in order to make use of the available set of internal electrochemical variables and mitigate internal mechanisms of cell degradation. (e.g., lithium plating); (2) we developed a dual-mode MPC closed-loop paradigm that suits the battery control problem with the objective of reducing computational effort by solving simpler optimization routines and guaranteeing stability; and finally (3) we developed a completely new approach of the use of a predictive control strategy where MPC is employed as a "smart sensor" for power estimation. Results are presented that show the comparative performance of the MPC algorithms for both EMC and PBROM These results highlight that dual-mode MPC can deliver optimal input current profiles by using a shorter horizon while still guaranteeing stability. Additionally, rigorous mathematical developments are presented for the development of the MPC algorithms. The use of MPC as a "smart sensor" presents it self as an appealing method for power estimation, since MPC permits a fully dynamic input profile that is able to achieve performance right at the proper constraint boundaries. Therefore, MPC is expected to produce accurate power limits for each computed sample time when compared to the Bisection method [1] which assumes constant input values over the prediction interval.

SRG110 Stirling Generator Dynamic Simulator Vibration Test Results and Analysis Correlation

NASA Technical Reports Server (NTRS)

Suarez, Vicente J.; Lewandowski, Edward J.; Callahan, John

2006-01-01

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 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 was 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.

Photovoltaic array: Power conditioner interface characteristics

NASA Technical Reports Server (NTRS)

Gonzalez, C. C.; Hill, G. M.; Ross, R. G., Jr.

1982-01-01

The electrical output (power, current, and voltage) of flat plate solar arrays changes constantly, due primarily to changes in cell temperature and irradiance level. As a result, array loads such as dc-to-ac power conditioners must be capable of accommodating widely varying input levels while maintaining operation at or near the maximum power point of the array. The array operating characteristics and extreme output limits necessary for the systematic design of array load interfaces under a wide variety of climatic conditions are studied. A number of interface parameters are examined, including optimum operating voltage, voltage energy, maximum power and current limits, and maximum open circuit voltage. The effect of array degradation and I-V curve fill factor or the array power conditioner interface is also discussed. Results are presented as normalized ratios of power conditioner parameters to array parameters, making the results universally applicable to a wide variety of system sizes, sites, and operating modes.

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.

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

Laros, James H.; Grant, Ryan; Levenhagen, Michael J.

Measuring and controlling the power and energy consumption of high performance computing systems by various components in the software stack is an active research area. Implementations in lower level software layers are beginning to emerge in some production systems, which is very welcome. To be most effective, a portable interface to measurement and control features would significantly facilitate participation by all levels of the software stack. We present a proposal for a standard power Application Programming Interface (API) that endeavors to cover the entire software space, from generic hardware interfaces to the input from the computer facility manager.

Comprehensive evaluation of power grid projects' investment benefits under the reform of transmission and distribution price

NASA Astrophysics Data System (ADS)

Wang, Yongli; Wang, Gang; Zuo, Yi; Fan, Lisha; Ling, Yunpeng

2017-03-01

On March 15, 2015, the Central Office issued the "Opinions on Further Deepening the Reform of Electric Power System" (Zhong Fa No. 9). This policy marks the central government officially opened a new round of electricity reform. As a programmatic document under the new situation to comprehensively promote the reform of the power system, No. 9 document will be approved as a separate transmission and distribution of electricity prices, which is the first task of promoting the reform of the power system. Grid tariff reform is not only the transmission and distribution price of a separate approval, more of the grid company input-output relationship and many other aspects of deep-level adjustments. Under the background of the reform of the transmission and distribution price, the main factors affecting the input-output relationship, such as the main business, electricity pricing, and investment approval, financial accounting and so on, have changed significantly. The paper designed the comprehensive evaluation index system of power grid projects' investment benefits under the reform of transmission and distribution price to improve the investment efficiency of power grid projects after the power reform in China.

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

Lentine, Anthony L.; Cox, Jonathan Albert

Methods and systems for stabilizing a resonant modulator include receiving pre-modulation and post-modulation portions of a carrier signal, determining the average power from these portions, comparing an average input power to the average output power, and operating a heater coupled to the modulator based on the comparison. One system includes a pair of input structures, one or more processing elements, a comparator, and a control element. The input structures are configured to extract pre-modulation and post-modulation portions of a carrier signal. The processing elements are configured to determine average powers from the extracted portions. The comparator is configured to comparemore » the average input power and the average output power. The control element operates a heater coupled to the modulator based on the comparison.« less

High Input Voltage, Silicon Carbide Power Processing Unit Performance Demonstration

NASA Technical Reports Server (NTRS)

Bozak, Karin E.; Pinero, Luis R.; Scheidegger, Robert J.; Aulisio, Michael V.; Gonzalez, Marcelo C.; Birchenough, Arthur G.

2015-01-01

A silicon carbide brassboard power processing unit has been developed by the NASA Glenn Research Center in Cleveland, Ohio. The power processing unit operates from two sources: a nominal 300 Volt high voltage input bus and a nominal 28 Volt low voltage input bus. The design of the power processing unit includes four low voltage, low power auxiliary supplies, and two parallel 7.5 kilowatt (kW) discharge power supplies that are capable of providing up to 15 kilowatts of total power at 300 to 500 Volts (V) to the thruster. Additionally, the unit contains a housekeeping supply, high voltage input filter, low voltage input filter, and master control board, such that the complete brassboard unit is capable of operating a 12.5 kilowatt Hall effect thruster. The performance of the unit was characterized under both ambient and thermal vacuum test conditions, and the results demonstrate exceptional performance with full power efficiencies exceeding 97%. The unit was also tested with a 12.5kW Hall effect thruster to verify compatibility and output filter specifications. With space-qualified silicon carbide or similar high voltage, high efficiency power devices, this would provide a design solution to address the need for high power electric propulsion systems.

Development of model reference adaptive control theory for electric power plant control applications

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

Mabius, L.E.

1982-09-15

The scope of this effort includes the theoretical development of a multi-input, multi-output (MIMO) Model Reference Control (MRC) algorithm, (i.e., model following control law), Model Reference Adaptive Control (MRAC) algorithm and the formulation of a nonlinear model of a typical electric power plant. Previous single-input, single-output MRAC algorithm designs have been generalized to MIMO MRAC designs using the MIMO MRC algorithm. This MRC algorithm, which has been developed using Command Generator Tracker methodologies, represents the steady state behavior (in the adaptive sense) of the MRAC algorithm. The MRC algorithm is a fundamental component in the MRAC design and stability analysis.more » An enhanced MRC algorithm, which has been developed for systems with more controls than regulated outputs, alleviates the MRC stability constraint of stable plant transmission zeroes. The nonlinear power plant model is based on the Cromby model with the addition of a governor valve management algorithm, turbine dynamics and turbine interactions with extraction flows. An application of the MRC algorithm to a linearization of this model demonstrates its applicability to power plant systems. In particular, the generated power changes at 7% per minute while throttle pressure and temperature, reheat temperature and drum level are held constant with a reasonable level of control. The enhanced algorithm reduces significantly control fluctuations without modifying the output response.« less

Mid-IR soliton compression in silicon optical fibers and fiber tapers.

PubMed

Peacock, Anna C

2012-03-01

Numerical simulations are used to investigate soliton compression in silicon core optical fibers at 2.3 μm in the mid-infrared waveguide regime. Compression in both standard silicon fibers and fiber tapers is compared to establish the relative compression ratios for a range of input pulse conditions. The results show that tapered fibers can be used to obtain higher levels of compression for moderate soliton orders and thus lower input powers. © 2012 Optical Society of America

Bi-Level Arbitrage Potential Evaluation for Grid-Scale Energy Storage Considering Wind Power and LMP Smoothing Effect

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

Cui, Hantao; Li, Fangxing; Fang, Xin

Our paper deals with extended-term energy storage (ES) arbitrage problems to maximize the annual revenue in deregulated power systems with high penetration wind power. The conventional ES arbitrage model takes the locational marginal prices (LMP) as an input and is unable to account for the impacts of ES operations on system LMPs. This paper proposes a bi-level ES arbitrage model, where the upper level maximizes the ES arbitrage revenue and the lower level simulates the market clearing process considering wind power and ES. The bi-level model is formulated as a mathematical program with equilibrium constraints (MPEC) and then recast intomore » a mixed-integer linear programming (MILP) using strong duality theory. Wind power fluctuations are characterized by the GARCH forecast model and the forecast error is modeled by forecast-bin based Beta distributions. Case studies are performed on a modified PJM 5-bus system and an IEEE 118-bus system with a weekly time horizon over an annual term to show the validity of the proposed bi-level model. The results from the conventional model and the bi-level model are compared under different ES power and energy ratings, and also various load and wind penetration levels.« less

Bi-Level Arbitrage Potential Evaluation for Grid-Scale Energy Storage Considering Wind Power and LMP Smoothing Effect

DOE PAGES

Cui, Hantao; Li, Fangxing; Fang, Xin; ...

2017-10-04

Our paper deals with extended-term energy storage (ES) arbitrage problems to maximize the annual revenue in deregulated power systems with high penetration wind power. The conventional ES arbitrage model takes the locational marginal prices (LMP) as an input and is unable to account for the impacts of ES operations on system LMPs. This paper proposes a bi-level ES arbitrage model, where the upper level maximizes the ES arbitrage revenue and the lower level simulates the market clearing process considering wind power and ES. The bi-level model is formulated as a mathematical program with equilibrium constraints (MPEC) and then recast intomore » a mixed-integer linear programming (MILP) using strong duality theory. Wind power fluctuations are characterized by the GARCH forecast model and the forecast error is modeled by forecast-bin based Beta distributions. Case studies are performed on a modified PJM 5-bus system and an IEEE 118-bus system with a weekly time horizon over an annual term to show the validity of the proposed bi-level model. The results from the conventional model and the bi-level model are compared under different ES power and energy ratings, and also various load and wind penetration levels.« less

High Power Light Gas Helicon Plasma Source For VASMIR

NASA Technical Reports Server (NTRS)

Squire, J. P.; Chang-Diaz, F. R.; Glover, T. W.; Jacobson, V. T.; McCaskill, G. E.; Winter, D. S.; Baity, F. W.; Carter, M. D.; Goulding, R. H.

2004-01-01

The VASIMR space propulsion development effort relies on a high power (greater than 10kW) helicon source to produce a dense flowing plasma (H, D and He) target for ion cyclotron resonance (ICR) acceleration of the ions. Subsequent expansion in an expanding magnetic field (magnetic nozzle) converts ion lunetic energy to directed momentum. This plasma source must have critical features to enable an effective propulsion device. First, it must ionize most of the input neutral flux of gas, thus producing a plasma stream with a high degree of ionization for application of ICR power. This avoids propellant waste and potential power losses due to charge exchange. Next, the plasma stream must flow into a region of high magnetic field (approximately 0.5 T) for efficient ICR acceleration. Third, the ratio of input power to plasma flux must be low, providing an energy per ion-electron pair approaching 100 eV. Lastly, the source must be robust and capable of very long life-times (years). In our helicon experiment (VX-10) we have measured a ratio of input gas to plasma flux near 100%. The plasma flows from the helicon region (B approximately 0.1 T) into a region with a peak magnetic field of 0.8 T. The energy input per ion-electron pair has been measured at 300 plus or minus 100 eV. Recent results at Oak Ridge National Laboratory (ORNL) show an enhanced efficiency mode of operation with a high power density, over 5 kW in a 5 cm diameter tube. Our helicon is presently 9 cm in diameter and operates up to 3.5 kW of input power. An upgrade to a power level of 10 kW is underway. Much of our recent work has been with a Boswell double-saddle antenna design. We are also converting the antenna design to a helical type. With these modifications, we anticipate an improvement in the ionization efficiency. This paper presents the results from scaling the helicon in the VX-10 device from 3.5 to 10 kW. We also compare the operation with a double-saddle to a helical antenna design. Finally, we discuss modeling of these configurations using ORNL's EMIR code.

Evaluation of a microwave high-power reception-conversion array for wireless power transmission

NASA Technical Reports Server (NTRS)

Dickinson, R. M.

1975-01-01

Initial performance tests of a 24-sq m area array of rectenna elements are presented. The array is used as the receiving portion of a wireless microwave power transmission engineering verification test system. The transmitting antenna was located at a range of 1.54 km. Output dc voltage and power, input RF power, efficiency, and operating temperatures were obtained for a variety of dc load and RF incident power levels at 2388 MHz. Incident peak RF intensities of up to 170 mW/sq cm yielded up to 30.4 kW of dc output power. The highest derived collection-conversion efficiency of the array was greater than 80 percent.

Human Powered Centrifuge

NASA Technical Reports Server (NTRS)

Mulenburg, Gerald M. (Inventor); Vernikos, Joan (Inventor)

1997-01-01

A human powered centrifuge has independently established turntable angular velocity and human power input. A control system allows excess input power to be stored as electric energy in a battery or dissipated as heat through a resistors. In a mechanical embodiment, the excess power is dissipated in a friction brake.

Mecanismes physiques et fondements theoriques de la recuperation d'energie micro-ondes ambiante pour les dispositifs sans fil a faible consommation

NASA Astrophysics Data System (ADS)

Petzl Lorenz, Carlos Henrique

Powering low consumption and low duty cycle devices and circuits using Ambient Microwave Energy Harvesting (AMEH) has been the subject of several investigations in recent years. The interest for this research topic has been promoted mainly by various and new applications driven mainly by the Internet of things, Building Automation and new developments in devices for the Body Area Networks. A common characteristic among several of these applications is the need for a wireless source which does not require regular maintenance, and has a small size and low weight. Batteries are often too cumbersome and require a maintenance plan to recharge or replace them, which is not always possible. A new source of energy is thus necessary. Ambient energy harvesting is proposed as an alternative source of power to these low power consumption devices and circuits. This M.A.Sc. work is developed to explore the microwave ambient energy harvesting using diode rectifier circuits. A mathematical model is first developed to explain the mechanisms that contribute to the process of recovery of microwave energy in the range of power found in the ambient microwave energy harvesting applications. An evaluation of this model is made using simulation results and then measurements results from three prototypes developed under this M.A.Sc. program. The results show an excellent agreement between the three methods. The developed model includes losses in the parasitic components of the non-linear element used for the rectification of energy as well as the impedance matching network insertion losses. Based on this model, two possible ways of improving the efficiency of ambient microwave power rectifiers at the power levels found in the AMEH are explored. In this work, it is considered that the AMEH takes place within the range of powers with a peak value of -30 dBm, however at average power levels well below this threshold. First, a cooperative hybrid circuit of ambient energy harvesting is presented where collected microwave and mechanical energies are converted in a cooperative manner through a single nonlinear component. Theory, simulations and measurements show that the total power recovered by the proposed scheme can provide up to twice the efficiency of a circuit combining the output of two independent harvesters. Then, a work demonstrating for the first time that the limitations of a Schottky diode harvester can be overcome by using backward tunnel diodes is presented. It is shown that the limitation reached by the Schottky diodes half a century ago can be overcome thanks to a higher current responsivity obtained through tunneling transport. The measured power recovery efficiency was equal to 18.2% when a -30 dBm signal at 2.4 GHz was applied to the input of the microwave energy harvesting circuit. The efficiency of conversion for a similar circuit using Schottky diodes, which is presented in the first chapter together with the mathematical model, does not exceed 11% at the same input power level and similar frequency. On the date of publication of the articles presented in this thesis, the highest published microwave power conversion efficiency was close to 5% for input power levels equal to -30 dBm and frequency close to 2 GHz. Finally, an application of microwave power transfer is presented. A rectenna operating at 94 GHz is built and measured, an energy conversion efficiency equal to 37.7% was obtained for an input power equal to 3 dBm. This rectenna is proposed as an alternative power source for microrobots, which may not use batteries due to their small size and light weight.

The Impact of Wind Development on County-Level Income and Employment: A Review of Methods and an Empirical Analysis

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

Eric Lantz

2012-09-21

To gain an understanding of the long-term county-level impacts from a large sample of wind power projects and to understand the potential significance of methodological criticisms, the U.S. Department of Agriculture, the Lawrence Berkeley National Laboratory, and the National Renewable Energy Laboratory recently joined efforts to complete a first-of-its-kind study that quantifies the annual impact on county-level personal income resulting from wind power installations in nearly 130 counties across 12 states. The results of this study as well as a comparison with the prior county-level estimates generated from input-output models, are summarized in the fact sheet.

Analysis of key factors influencing the evaporation performances of an oriented linear cutting copper fiber sintered felt

NASA Astrophysics Data System (ADS)

Pan, Minqiang; Zhong, Yujian

2018-01-01

Porous structure can effectively enhance the heat transfer efficiency. A kind of micro vaporizer using the oriented linear cutting copper fiber sintered felt is proposed in this work. Multiple long cutting copper fibers are firstly fabricated with a multi-tooth tool and then sintered together in parallel to form uniform thickness metal fiber sintered felts that provided a characteristic of oriented microchannels. The temperature rise response and thermal conversion efficiency are experimentally investigated to evaluate the influences of porosity, surface structure, feed flow rate and input power on the evaporation characteristics. It is indicated that the temperature rise response of water is mainly affected by input power and feed flow rate. High input power and low feed flow rate present better temperature rise response of water. Porosity rather than surface structure plays an important role in the temperature rise response of water at a relatively high input power. The thermal conversion efficiency is dominated by the input power and surface structure. The oriented linear cutting copper fiber sintered felts for three kinds of porosities show better thermal conversion efficiency than that of the oriented linear copper wire sintered felt when the input power is less than 115 W. All the sintered felts have almost the same performance of thermal conversion at a high input power.

47 CFR 15.31 - Measurement standards.

Code of Federal Regulations, 2010 CFR

2010-10-01

... the installation site, such as perimeter protection systems, carrier current systems, and systems... variation of the input power or the radiated signal level of the fundamental frequency component of the... nominal rated supply voltage. For battery operated equipment, the equipment tests shall be performed using...

Effect of Power Point Enhanced Teaching (Visual Input) on Iranian Intermediate EFL Learners' Listening Comprehension Ability

ERIC Educational Resources Information Center

Sehati, Samira; Khodabandehlou, Morteza

2017-01-01

The present investigation was an attempt to study on the effect of power point enhanced teaching (visual input) on Iranian Intermediate EFL learners' listening comprehension ability. To that end, a null hypothesis was formulated as power point enhanced teaching (visual input) has no effect on Iranian Intermediate EFL learners' listening…

The capacity credit of grid-connected photovoltaic systems

NASA Astrophysics Data System (ADS)

Alsema, E. A.; van Wijk, A. J. M.; Turkenburg, W. C.

The capacity credit due photovoltaic (PV) power plants if integrated into the Netherlands grid was investigated, together with an estimate of the total allowable penetration. An hourly simulation was performed based on meteorological data from five stations and considering tilted surfaces, the current grid load pattern, and the load pattern after PV-power augmentation. The reliability of the grid was assessed in terms of a loss of load probability analysis, assuming power drops were limited to 1 GW. A projected tolerance for 2.5 GW of PV power was calculated. Peak demands were determined to be highest in winter, contrary to highest insolation levels; however, daily insolation levels coincided with daily peak demands. Combining the PV input with an equal amount of wind turbine power production was found to augment the capacity credit for both at aggregate outputs of 2-4 GW.

Network-State Modulation of Power-Law Frequency-Scaling in Visual Cortical Neurons

PubMed Central

Béhuret, Sébastien; Baudot, Pierre; Yger, Pierre; Bal, Thierry; Destexhe, Alain; Frégnac, Yves

2009-01-01

Various types of neural-based signals, such as EEG, local field potentials and intracellular synaptic potentials, integrate multiple sources of activity distributed across large assemblies. They have in common a power-law frequency-scaling structure at high frequencies, but it is still unclear whether this scaling property is dominated by intrinsic neuronal properties or by network activity. The latter case is particularly interesting because if frequency-scaling reflects the network state it could be used to characterize the functional impact of the connectivity. In intracellularly recorded neurons of cat primary visual cortex in vivo, the power spectral density of Vm activity displays a power-law structure at high frequencies with a fractional scaling exponent. We show that this exponent is not constant, but depends on the visual statistics used to drive the network. To investigate the determinants of this frequency-scaling, we considered a generic recurrent model of cortex receiving a retinotopically organized external input. Similarly to the in vivo case, our in computo simulations show that the scaling exponent reflects the correlation level imposed in the input. This systematic dependence was also replicated at the single cell level, by controlling independently, in a parametric way, the strength and the temporal decay of the pairwise correlation between presynaptic inputs. This last model was implemented in vitro by imposing the correlation control in artificial presynaptic spike trains through dynamic-clamp techniques. These in vitro manipulations induced a modulation of the scaling exponent, similar to that observed in vivo and predicted in computo. We conclude that the frequency-scaling exponent of the Vm reflects stimulus-driven correlations in the cortical network activity. Therefore, we propose that the scaling exponent could be used to read-out the “effective” connectivity responsible for the dynamical signature of the population signals measured at different integration levels, from Vm to LFP, EEG and fMRI. PMID:19779556

Network-state modulation of power-law frequency-scaling in visual cortical neurons.

PubMed

El Boustani, Sami; Marre, Olivier; Béhuret, Sébastien; Baudot, Pierre; Yger, Pierre; Bal, Thierry; Destexhe, Alain; Frégnac, Yves

2009-09-01

Various types of neural-based signals, such as EEG, local field potentials and intracellular synaptic potentials, integrate multiple sources of activity distributed across large assemblies. They have in common a power-law frequency-scaling structure at high frequencies, but it is still unclear whether this scaling property is dominated by intrinsic neuronal properties or by network activity. The latter case is particularly interesting because if frequency-scaling reflects the network state it could be used to characterize the functional impact of the connectivity. In intracellularly recorded neurons of cat primary visual cortex in vivo, the power spectral density of V(m) activity displays a power-law structure at high frequencies with a fractional scaling exponent. We show that this exponent is not constant, but depends on the visual statistics used to drive the network. To investigate the determinants of this frequency-scaling, we considered a generic recurrent model of cortex receiving a retinotopically organized external input. Similarly to the in vivo case, our in computo simulations show that the scaling exponent reflects the correlation level imposed in the input. This systematic dependence was also replicated at the single cell level, by controlling independently, in a parametric way, the strength and the temporal decay of the pairwise correlation between presynaptic inputs. This last model was implemented in vitro by imposing the correlation control in artificial presynaptic spike trains through dynamic-clamp techniques. These in vitro manipulations induced a modulation of the scaling exponent, similar to that observed in vivo and predicted in computo. We conclude that the frequency-scaling exponent of the V(m) reflects stimulus-driven correlations in the cortical network activity. Therefore, we propose that the scaling exponent could be used to read-out the "effective" connectivity responsible for the dynamical signature of the population signals measured at different integration levels, from Vm to LFP, EEG and fMRI.

Microwave Driven Magnetic Plasma Accelerator Studies (CYCLOPS)

NASA Technical Reports Server (NTRS)

Crimi, G. F.; Eckert, A. C.; Miller, D. B.

1967-01-01

A microwave-driven cyclotron resonance plasma acceleration device was investigated using argon, krypton, xenon, and mercury as propellants. Limited ranges of propellant flow rate, input power, and magnetic field strength were used. Over-all efficiencies (including the 65% efficiency of the input polarizer) less than 10% were obtained for specific impulse values between 500 and 1500 sec. Power transfer efficiencies, however, approached 100% of the input power available in the right-hand component of the incident circularly polarized radiation. Beam diagnostics using Langmuir probes, cold gas mapping, r-f mapping and ion energy analyses were performed in conjunction with an engine operating in a pulsed mode. Measurements of transverse electron energies at the position of cyclotron resonant absorption yielded energy values more than an order of magnitude lower than anticipated. The measured electron energies were, however, consistent with the low values of average ion energy measured by retarding potential techniques. The low values of average ion energy were also consistent with the measured thrust values. It is hypothesized that ionization and radiation limit the electron kinetic energy to low-values thus limiting the energy which is finally transferred to the ion. Thermalization by electron-electron collision was also identified as an additional loss mechanism. The use of light alkali metals, which have relatively few low lying energy levels to excite, with the input power to mass ratio selected so as to limit the electron energies to less than the second ionization potential, is suggested. It is concluded, however, that the over-all efficiency for such propellants would be less than 40 per cent.

Minimal Power Latch for Single-Slope ADCs

NASA Technical Reports Server (NTRS)

Hancock, Bruce R.

2013-01-01

Column-parallel analog-to-digital converters (ADCs) for imagers involve simultaneous operation of many ADCs. Single-slope ADCs are well adapted to this use because of their simplicity. Each ADC contains a comparator, comparing its input signal level to an increasing reference signal (ramp). When the ramp is equal to the input, the comparator triggers a latch that captures an encoded counter value (code). Knowing the captured code, the ramp value and hence the input signal are determined. In a column-parallel ADC, each column contains only the comparator and the latches; the ramp and code generation are shared. In conventional latch or flip-flop circuits, there is an input stage that tracks the input signal, and this stage consumes switching current every time the input changes. With many columns, many bits, and high code rates, this switching current can be substantial. It will also generate noise that may corrupt the analog signals. A latch was designed that does not track the input, and consumes power only at the instant of latching the data value. The circuit consists of two S-R (set-reset) latches, gated by the comparator. One is set by high data values and the other by low data values. The latches are cross-coupled so that the first one to set blocks the other. In order that the input data not need an inversion, which would consume power, the two latches are made in complementary polarity. This requires complementary gates from the comparator, instead of complementary data values, but the comparator only triggers once per conversion, and usually has complementary outputs to begin with. An efficient CMOS (complementary metal oxide semiconductor) implementation of this circuit is shown in the figure, where C is the comparator output, D is the data (code), and Q0 and Q1 are the outputs indicating the capture of a zero or one value. The latch for Q0 has a negative-true set signal and output, and is implemented using OR-AND-INVERT logic, while the latch for Q1 uses positive- true signals and is implemented using AND-OR-INVERT logic. In this implementation, both latches are cleared when the comparator is reset. Two redundant transistors are removed from the reset side of each latch, making for a compact layout. CMOS imagers with column-parallel ADCs have demonstrated high performance for remote sensing applications. With this latch circuit, the power consumption and noise can be further reduced. This innovation can be used in CMOS imagers and very-low-power electronics

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

Wierer, Jonathan J.; Tsao, Jeffrey Y.; Sizov, Dmitry S.

Solid-state lighting (SSL) is now the most efficient source of high color quality white light ever created. Nevertheless, the blue InGaN light-emitting diodes (LEDs) that are the light engine of SSL still have significant performance limitations. Foremost among these is the decrease in efficiency at high input current densities widely known as “efficiency droop.” Efficiency droop limits input power densities, contrary to the desire to produce more photons per unit LED chip area and to make SSL more affordable. Pending a solution to efficiency droop, an alternative device could be a blue laser diode (LD). LDs, operated in stimulated emission,more » can have high efficiencies at much higher input power densities than LEDs can. In this article, LEDs and LDs for future SSL are explored by comparing: their current state-of-the-art input-power-density-dependent power-conversion efficiencies; potential improvements both in their peak power-conversion efficiencies and in the input power densities at which those efficiencies peak; and their economics for practical SSL.« less

Performance of a Low-Power Cylindrical Hall Thruster

NASA Technical Reports Server (NTRS)

Polzin, Kurt A.; Markusic, Thomas E.; Stanojev, Boris J.; Dehoyos, Amado; Raitses, Yevgeny; Smirnov, Artem; Fisch, Nathaniel J.

2007-01-01

Recent mission studies have shown that a Hall thruster which operates at relatively constant thrust efficiency (45-55%) over a broad power range (300W - 3kW) is enabling for deep space science missions when compared with slate-of-the-art ion thrusters. While conventional (annular) Hall thrusters can operate at high thrust efficiency at kW power levels, it is difficult to construct one that operates over a broad power envelope down to 0 (100 W) while maintaining relatively high efficiency. In this note we report the measured performance (I(sub sp), thrust and efficiency) of a cylindrical Hall thruster operating at 0 (100 W) input power.

47 CFR 73.51 - Determining operating power.

Code of Federal Regulations, 2011 CFR

2011-10-01

... stage of the transmitter, using the following formula: Where: Antenna input power = Ep × Ip × F Ep=DC input voltage of final radio stage. Ip=Total DC input current of final radio stage. F= Efficiency factor...

Integrated controls design optimization

DOEpatents

Lou, Xinsheng; Neuschaefer, Carl H.

2015-09-01

A control system (207) for optimizing a chemical looping process of a power plant includes an optimizer (420), an income algorithm (230) and a cost algorithm (225) and a chemical looping process models. The process models are used to predict the process outputs from process input variables. Some of the process in puts and output variables are related to the income of the plant; and some others are related to the cost of the plant operations. The income algorithm (230) provides an income input to the optimizer (420) based on a plurality of input parameters (215) of the power plant. The cost algorithm (225) provides a cost input to the optimizer (420) based on a plurality of output parameters (220) of the power plant. The optimizer (420) determines an optimized operating parameter solution based on at least one of the income input and the cost input, and supplies the optimized operating parameter solution to the power plant.

Surface EMG and intra-socket force measurement to control a prosthetic device

NASA Astrophysics Data System (ADS)

Sanford, Joe; Patterson, Rita; Popa, Dan

2015-06-01

Surface electromyography (SEMG) has been shown to be a robust and reliable interaction method allowing for basic control of powered prosthetic devices. Research has shown a marked decrease in EMG-classification efficiency throughout activities of daily life due to socket shift and movement and fatigue as well as changes in degree of fit of the socket throughout the subject's lifetime. Users with the most severe levels of amputation require the most complex devices with the greatest number of degrees of freedom. Controlling complex dexterous devices with limited available inputs requires the addition of sensing and interaction modalities. However, the larger the amputation severity, the fewer viable SEMG sites are available as control inputs. Previous work reported the use of intra-socket pressure, as measured during wrist flexion and extension, and has shown that it is possible to control a powered prosthetic device with pressure sensors. In this paper, we present data correlations of SEMG data with intra-socket pressure data. Surface EMG sensors and force sensors were housed within a simulated prosthetic cuff fit to a healthy-limbed subject. EMG and intra-socket force data was collected from inside the cuff as a subject performed pre-defined grip motions with their dominant hand. Data fusion algorithms were explored and allowed a subject to use both intra-socket pressure and SEMG data as control inputs for a powered prosthetic device. This additional input modality allows for an improvement in input classification as well as information regarding socket fit through out activities of daily life.

Continuous Time Level Crossing Sampling ADC for Bio-Potential Recording Systems

PubMed Central

Tang, Wei; Osman, Ahmad; Kim, Dongsoo; Goldstein, Brian; Huang, Chenxi; Martini, Berin; Pieribone, Vincent A.

2013-01-01

In this paper we present a fixed window level crossing sampling analog to digital convertor for bio-potential recording sensors. This is the first proposed and fully implemented fixed window level crossing ADC without local DACs and clocks. The circuit is designed to reduce data size, power, and silicon area in future wireless neurophysiological sensor systems. We built a testing system to measure bio-potential signals and used it to evaluate the performance of the circuit. The bio-potential amplifier offers a gain of 53 dB within a bandwidth of 200 Hz-20 kHz. The input-referred rms noise is 2.8 µV. In the asynchronous level crossing ADC, the minimum delta resolution is 4 mV. The input signal frequency of the ADC is up to 5 kHz. The system was fabricated using the AMI 0.5 µm CMOS process. The chip size is 1.5 mm by 1.5 mm. The power consumption of the 4-channel system from a 3.3 V supply is 118.8 µW in the static state and 501.6 µW with a 240 kS/s sampling rate. The conversion efficiency is 1.6 nJ/conversion. PMID:24163640

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.

An Approach to Sensorless Detection of Human Input Torque and Its Application to Power Assist Motion in Electric Wheelchair

NASA Astrophysics Data System (ADS)

Kaida, Yukiko; Murakami, Toshiyuki

A wheelchair is an important apparatus of mobility for people with disability. Power-assist motion in an electric wheelchair is to expand the operator's field of activities. This paper describes force sensorless detection of human input torque. Reaction torque estimation observer calculates the total disturbance torque first. Then, the human input torque is extracted from the estimated disturbance. In power-assist motion, assist torque is synthesized according to the product of assist gain and the average torque of the right and left input torque. Finally, the proposed method is verified through the experiments of power-assist motion.

Quelling Cabin Noise in Turboprop Aircraft via Active Control

NASA Technical Reports Server (NTRS)

Kincaid, Rex K.; Laba, Keith E.; Padula, Sharon L.

1997-01-01

Cabin noise in turboprop aircraft causes passenger discomfort, airframe fatigue, and employee scheduling constraints due to OSHA standards for exposure to high levels of noise. The noise levels in the cabins of turboprop aircraft are typically 10 to 30 decibels louder than commercial jet noise levels. However. unlike jet noise the turboprop noise spectrum is dominated by a few low frequency tones. Active structural acoustic control is a method in which the control inputs (used to reduce interior noise) are applied directly to a vibrating structural acoustic system. The control concept modeled in this work is the application of in-plane force inputs to piezoceramic patches bonded to the wall of a vibrating cylinder. The goal is to determine the force inputs and locations for the piezoceramic actuators so that: (1) the interior noise is effectively damped; (2) the level of vibration of the cylinder shell is not increased; and (3) the power requirements needed to drive the actuators are not excessive. Computational experiments for data taken from a computer generated model and from a laboratory test article at NASA Langley Research Center are provided.

A new high dynamic range ROIC with smart light intensity control unit

NASA Astrophysics Data System (ADS)

Yazici, Melik; Ceylan, Omer; Shafique, Atia; Abbasi, Shahbaz; Galioglu, Arman; Gurbuz, Yasar

2017-05-01

This journal presents a new high dynamic range ROIC with smart pixel which consists of two pre-amplifiers that are controlled by a circuit inside the pixel. Each pixel automatically decides which pre-amplifier is used according to the incoming illumination level. Instead of using single pre-amplifier, two input pre-amplifiers, which are optimized for different signal levels, are placed inside each pixel. The smart circuit mechanism, which decides the best input circuit according to the incoming light level, is also designed for each pixel. In short, an individual pixel has the ability to select the best input amplifier circuit that performs the best/highest SNR for the incoming signal level. A 32 × 32 ROIC prototype chip is designed to demonstrate the concept in 0.18 μ m CMOS technology. The prototype is optimized for NIR and SWIR bands. Instead of a detector, process variation optimized current sources are placed inside the ROIC. The chip achieves minimum 8.6 e- input referred noise and 98.9 dB dynamic range. It has the highest dynamic range in the literature in terms of analog ROICs for SWIR band. It is operating in room temperature and power consumption is 2.8 μ W per pixel.

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

NASA Astrophysics Data System (ADS)

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

2018-04-01

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

Transient boiling heat transfer in saturated liquid nitrogen and F113 at standard and zero gravity

NASA Technical Reports Server (NTRS)

Oker, E.; Merte, H., Jr.

1973-01-01

Transient and steady state nucleate boiling in saturated LN2 and F113 at standard and near zero gravity conditions were investigated for the horizontal up, vertical and horizontal down orientations of the heating surface. Two distinct regimes of heat transfer mechanisms were observed during the interval from the step increase of power input to the onset of nucleate boiling: the conduction and convection dominated regimes. The time duration in each regime was considerably shorter with LN2 than with F113, and decreased as heat flux increased, as gravity was reduced, and as the orientation was changed from horizontal up to horizontal down. In transient boiling, boiling initiates at a single point following the step increase in power, and then spreads over the surface. The delay time for the inception of boiling at the first site, and the velocity of spread of boiling varies depending upon the heat flux, orientation, body force, surface roughness and liquid properties, and are a consequence of changes in boundary layer temperature levels associated with changes in natural convection. Following the step increase in power input, surface temperature overshoot and undershoot occur before the steady state boiling temperature level is established.

Advanced Stirling Convertor Dynamic Test Approach and Results

NASA Technical Reports Server (NTRS)

Meer, David W.; Hill, Dennis; Ursic, Joseph

2009-01-01

The U.S. Department of Energy (DOE), Lockheed Martin (LM), and NASA Glenn Research Center (GRC) have been developing the Advanced Stirling Radioisotope Generator (ASRG) for use as a power system for space science missions. As part of the extended operation testing of this power system, the Advanced Stirling Converters (ASC) at NASA John H. Glenn Research Center undergo a vibration test sequence intended to simulate the vibration history of an ASC used in an ASRG for a space mission. This sequence includes testing at Workmanship and Flight Acceptance levels interspersed with periods of extended operation to simulate pre and post fueling. The final step in the test sequence utilizes additional testing at Flight Acceptance levels to simulate launch. To better replicate the acceleration profile seen by an ASC incorporated into an ASRG, the input spectra used in testing the convertors was modified based on dynamic testing of the ASRG Engineering Unit ( ASRG-EU) at Lockheed Martin. This paper presents the vibration test plan for current and future ASC units, including the modified input spectra, and the results of recent tests using these spectra. The test results include data from several accelerometers mounted on the convertors as well as the piston position and output power variables.

Position-insensitive long range inductive power transfer

NASA Astrophysics Data System (ADS)

Kwan, Christopher H.; Lawson, James; Yates, David C.; Mitcheson, Paul D.

2014-11-01

This paper presents results of an improved inductive wireless power transfer system for reliable long range powering of sensors with milliwatt-level consumption. An ultra-low power flyback impedance emulator operating in open loop is used to present the optimal load to the receiver's resonant tank. Transmitter power modulation is implemented in order to maintain constant receiver power and to prevent damage to the receiver electronics caused by excessive received voltage. Received power is steady up to 3 m at around 30 mW. The receiver electronics and feedback system consumes 3.1 mW and so with a transmitter input power of 163.3 W the receiver becomes power neutral at 4.75 m. Such an IPT system can provide a reliable alternative to energy harvesters for supplying power concurrently to multiple remote sensors.

Hybrid zero-voltage switching (ZVS) control for power inverters

DOEpatents

Amirahmadi, Ahmadreza; Hu, Haibing; Batarseh, Issa

2016-11-01

A power inverter combination includes a half-bridge power inverter including first and second semiconductor power switches receiving input power having an intermediate node therebetween providing an inductor current through an inductor. A controller includes input comparison circuitry receiving the inductor current having outputs coupled to first inputs of pulse width modulation (PWM) generation circuitry, and a predictive control block having an output coupled to second inputs of the PWM generation circuitry. The predictive control block is coupled to receive a measure of Vin and an output voltage at a grid connection point. A memory stores a current control algorithm configured for resetting a PWM period for a switching signal applied to control nodes of the first and second power switch whenever the inductor current reaches a predetermined upper limit or a predetermined lower limit.

Input and output budgets of radiocesium concerning the forest floor in the mountain forest of Fukushima released from the TEPCO's Fukushima Dai-ichi nuclear power plant accident.

PubMed

Niizato, Tadafumi; Abe, Hironobu; Mitachi, Katsuaki; Sasaki, Yoshito; Ishii, Yasuo; Watanabe, Takayoshi

2016-09-01

Estimations of radiocesium input and output concerning the forest floor within a mountain forest region have been conducted in the north and central part of the Abukuma Mountains of Fukushima, northeast Japan, after a 2-3 year period following the TEPCO Fukushima Dai-ichi nuclear power plant accident. The radiocesium input and output associated with surface washoff, throughfall, stemflow, and litterfall processes at experimental plots installed on the forest floor of evergreen Japanese cedars and deciduous Konara oaks have been monitored. Despite the high output potential in the mountainous forest of Fukushima, the results at both monitoring locations show the radiocesium input to be 4-50 times higher than the output during the summer monsoon in Fukushima. These results indicate that the radiocesium tends to be preserved in the forest ecosystem due to extremely low output ratios (0.05%-0.19%). Thus, the associated fluxes throughout the circulation process are key issues for the projecting the environmental fate of the radiocesium levels, along with the subsequent reconstruction of life emphasized within the setting. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

NIF Ignition Target 3D Point Design

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

Jones, O; Marinak, M; Milovich, J

2008-11-05

We have developed an input file for running 3D NIF hohlraums that is optimized such that it can be run in 1-2 days on parallel computers. We have incorporated increasing levels of automation into the 3D input file: (1) Configuration controlled input files; (2) Common file for 2D and 3D, different types of capsules (symcap, etc.); and (3) Can obtain target dimensions, laser pulse, and diagnostics settings automatically from NIF Campaign Management Tool. Using 3D Hydra calculations to investigate different problems: (1) Intrinsic 3D asymmetry; (2) Tolerance to nonideal 3D effects (e.g. laser power balance, pointing errors); and (3) Syntheticmore » diagnostics.« less

Statistical inference, the bootstrap, and neural-network modeling with application to foreign exchange rates.

PubMed

White, H; Racine, J

2001-01-01

We propose tests for individual and joint irrelevance of network inputs. Such tests can be used to determine whether an input or group of inputs "belong" in a particular model, thus permitting valid statistical inference based on estimated feedforward neural-network models. The approaches employ well-known statistical resampling techniques. We conduct a small Monte Carlo experiment showing that our tests have reasonable level and power behavior, and we apply our methods to examine whether there are predictable regularities in foreign exchange rates. We find that exchange rates do appear to contain information that is exploitable for enhanced point prediction, but the nature of the predictive relations evolves through time.

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.

Uncertainty analysis of geothermal energy economics

NASA Astrophysics Data System (ADS)

Sener, Adil Caner

This dissertation research endeavors to explore geothermal energy economics by assessing and quantifying the uncertainties associated with the nature of geothermal energy and energy investments overall. The study introduces a stochastic geothermal cost model and a valuation approach for different geothermal power plant development scenarios. The Monte Carlo simulation technique is employed to obtain probability distributions of geothermal energy development costs and project net present values. In the study a stochastic cost model with incorporated dependence structure is defined and compared with the model where random variables are modeled as independent inputs. One of the goals of the study is to attempt to shed light on the long-standing modeling problem of dependence modeling between random input variables. The dependence between random input variables will be modeled by employing the method of copulas. The study focuses on four main types of geothermal power generation technologies and introduces a stochastic levelized cost model for each technology. Moreover, we also compare the levelized costs of natural gas combined cycle and coal-fired power plants with geothermal power plants. The input data used in the model relies on the cost data recently reported by government agencies and non-profit organizations, such as the Department of Energy, National Laboratories, California Energy Commission and Geothermal Energy Association. The second part of the study introduces the stochastic discounted cash flow valuation model for the geothermal technologies analyzed in the first phase. In this phase of the study, the Integrated Planning Model (IPM) software was used to forecast the revenue streams of geothermal assets under different price and regulation scenarios. These results are then combined to create a stochastic revenue forecast of the power plants. The uncertainties in gas prices and environmental regulations will be modeled and their potential impacts will be captured in the valuation model. Finally, the study will compare the probability distributions of development cost and project value and discusses the market penetration potential of the geothermal power generation. There is a recent world wide interest in geothermal utilization projects. There are several reasons for the recent popularity of geothermal energy, including the increasing volatility of fossil fuel prices, need for domestic energy sources, approaching carbon emission limitations and state renewable energy standards, increasing need for baseload units, and new technology to make geothermal energy more attractive for power generation. It is our hope that this study will contribute to the recent progress of geothermal energy by shedding light on the uncertainty of geothermal energy project costs.

A chip-scale, telecommunications-band frequency conversion interface for quantum emitters.

PubMed

Agha, Imad; Ates, Serkan; Davanço, Marcelo; Srinivasan, Kartik

2013-09-09

We describe a chip-scale, telecommunications-band frequency conversion interface designed for low-noise operation at wavelengths desirable for common single photon emitters. Four-wave-mixing Bragg scattering in silicon nitride waveguides is used to demonstrate frequency upconversion and downconversion between the 980 nm and 1550 nm wavelength regions, with signal-to-background levels > 10 and conversion efficiency of ≈ -60 dB at low continuous wave input pump powers (< 50 mW). Finite element simulations and the split-step Fourier method indicate that increased input powers of ≈ 10 W (produced by amplified nanosecond pulses, for example) will result in a conversion efficiency > 25 % in existing geometries. Finally, we present waveguide designs that can be used to connect shorter wavelength (637 nm to 852 nm) quantum emitters with 1550 nm.

A geothermal AMTEC system

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

Schuller, M.J.; LeMire, R.A.; Horner-Richardson, K.

1995-12-31

The Phillips Laboratory Power and Thermal Management Division (PL/VTP), with the support of ORION International Technologies, is investigating new methods of advanced thermal to electric power conversion for space and terrestrial applications. The alkali metal thermal-to-electric converter (AMTEC), manufactured primarily by Advanced Modular Power Systems (AMPS) of Ann Arbor, MI, has reached a level of technological maturity which would allow its use in a constant, unattended thermal source, such as a geothermal field. Approximately 95,000 square miles in the western United States has hot dry rock with thermal gradients of 60 C/km and higher. Several places in the United Statesmore » and the world have thermal gradients of 500 C/km. Such heat sources represent an excellent thermal source for a system of modular power units using AMTEC devices to convert the heat to electricity. AMTEC cells using sodium as a working fluid require heat input at temperatures between 500 and 1,000 C to generate power. The present state of the art is capable of 15% efficiency with 800 C heat input and has demonstrated 18% efficiency for single cells. This paper discusses the basics of AMTEC operation, current drilling technology as a cost driver, design of modular AMTEC power units, heat rejection technologies, materials considerations, and estimates of power production from a geothermal AMTEC concept.« less

A CMOS Low-Power Optical Front-End for 5 Gbps Applications

NASA Astrophysics Data System (ADS)

Zohoori, Soorena; Dolatshahi, Mehdi

2018-01-01

In this paper, a new low-power optical receiver front-end is proposed in 90 nm CMOS technology for 5 Gb/s AApplications. However, to improve the gain-bandwidth trade-off, the proposed Trans-Impedance Amplifier (TIA) uses an active modified inverter-based topology followed by a common-source amplifier, which uses active inductive peaking technique to enhance the frequency bandwidth in an increased gain level for a reasonable power consumption value. The proposed TIA is analyzed and simulated in HSPICE using 90 nm CMOS technology parameters. Simulation results show a 53.5dBΩ trans-impedance gain, 3.5 GHz frequency bandwidth, 16.8pA/√Hz input referred noise, and 1.28 mW of power consumption at 1V supply voltage. The Optical receiver is completed using three stages of differential limiting amplifiers (LAs), which provide 27 dB voltage gain while consume 3.1 mW of power. Finally, the whole optical receiver front-end consumes only 5.6 mW of power at 1 V supply and amplifies the input signal by 80 dB, while providing 3.7 GHz of frequency bandwidth. Finally, the simulation results indicate that the proposed optical receiver is a proper candidate to be used in a low-power 5 Gbps optical communication system.

Ultra-low-power conversion and management techniques for thermoelectric energy harvesting applications

NASA Astrophysics Data System (ADS)

Fleming, Jerry W.

2010-04-01

Thermoelectric energy harvesting has increasingly gained acceptance as a potential power source that can be used for numerous commercial and military applications. However, power electronic designers have struggled to incorporate energy harvesting methods into their designs due to the relatively small voltage levels available from many harvesting device technologies. In order to bridge this gap, an ultra-low input voltage power conversion method is needed to convert small amounts of scavenged energy into a usable form of electricity. Such a method would be an enabler for new and improved medical devices, sensor systems, and other portable electronic products. This paper addresses the technical challenges involved in ultra-low-voltage power conversion by providing a solution utilizing novel power conversion techniques and applied technologies. Our solution utilizes intelligent power management techniques to control unknown startup conditions. The load and supply management functionality is also controlled in a deterministic manner. The DC to DC converter input operating voltage is 20mV with a conversion efficiency of 90% or more. The output voltage is stored into a storage device such as an ultra-capacitor or lithium-ion battery for use during brown-out or unfavorable harvesting conditions. Applications requiring modular, low power, extended maintenance cycles, such as wireless instrumentation would significantly benefit from the novel power conversion and harvesting techniques outlined in this paper.

Binary power multiplier for electromagnetic energy

DOEpatents

Farkas, Zoltan D.

1988-01-01

A technique for converting electromagnetic pulses to higher power amplitude and shorter duration, in binary multiples, splits an input pulse into two channels, and subjects the pulses in the two channels to a number of binary pulse compression operations. Each pulse compression operation entails combining the pulses in both input channels and selectively steering the combined power to one output channel during the leading half of the pulses and to the other output channel during the trailing half of the pulses, and then delaying the pulse in the first output channel by an amount equal to half the initial pulse duration. Apparatus for carrying out each of the binary multiplication operation preferably includes a four-port coupler (such as a 3 dB hybrid), which operates on power inputs at a pair of input ports by directing the combined power to either of a pair of output ports, depending on the relative phase of the inputs. Therefore, by appropriately phase coding the pulses prior to any of the pulse compression stages, the entire pulse compression (with associated binary power multiplication) can be carried out solely with passive elements.

RF safety assessment of a bilateral four-channel transmit/receive 7 Tesla breast coil: SAR versus tissue temperature limits.

PubMed

Fiedler, Thomas M; Ladd, Mark E; Bitz, Andreas K

2017-01-01

The purpose of this work was to perform an RF safety evaluation for a bilateral four-channel transmit/receive breast coil and to determine the maximum permissible input power for which RF exposure of the subject stays within recommended limits. The safety evaluation was done based on SAR as well as on temperature simulations. In comparison to SAR, temperature is more directly correlated with tissue damage, which allows a more precise safety assessment. The temperature simulations were performed by applying three different blood perfusion models as well as two different ambient temperatures. The goal was to evaluate whether the SAR and temperature distributions correlate inside the human body and whether SAR or temperature is more conservative with respect to the limits specified by the IEC. A simulation model was constructed including coil housing and MR environment. Lumped elements and feed networks were modeled by a network co-simulation. The model was validated by comparison of S-parameters and B 1 + maps obtained in an anatomical phantom. Three numerical body models were generated based on 3 Tesla MRI images to conform to the coil housing. SAR calculations were performed and the maximal permissible input power was calculated based on IEC guidelines. Temperature simulations were performed based on the Pennes bioheat equation with the power absorption from the RF simulations as heat source. The blood perfusion was modeled as constant to reflect impaired patients as well as with a linear and exponential temperature-dependent increase to reflect two possible models for healthy subjects. Two ambient temperatures were considered to account for cooling effects from the environment. The simulation model was validated with a mean deviation of 3% between measurement and simulation results. The highest 10 g-averaged SAR was found in lung and muscle tissue on the right side of the upper torso. The maximum permissible input power was calculated to be 17 W. The temperature simulations showed that temperature maximums do not correlate well with the position of the SAR maximums in all considered cases. The body models with an exponential blood perfusion increase did not exceed the temperature limit when an RF power according to the SAR limit was applied; in this case, a higher input power level by up to 73% would be allowed. The models with a constant or linear perfusion exceeded the limit for the local temperature when the local SAR limit was adhered to and would require a decrease in the input power level by up to 62%. The maximum permissible input power was determined based on SAR simulations with three newly generated body models and compared with results from temperature simulations. While SAR calculations are state-of-the-art and well defined as they are based on more or less well-known material parameters, temperature simulations depend strongly on additional material, environmental and physiological parameters. The simulations demonstrated that more consideration needs be made by the MR community in defining the parameters for temperature simulations in order to apply temperature limits instead of SAR limits in the context of MR RF safety evaluations. © 2016 American Association of Physicists in Medicine.

Gallium Arsenide Domino Circuit

NASA Technical Reports Server (NTRS)

Yang, Long; Long, Stephen I.

1990-01-01

Advantages include reduced power and high speed. Experimental gallium arsenide field-effect-transistor (FET) domino circuit replicated in large numbers for use in dynamic-logic systems. Name of circuit denotes mode of operation, which logic signals propagate from each stage to next when successive stages operated at slightly staggered clock cycles, in manner reminiscent of dominoes falling in a row. Building block of domino circuit includes input, inverter, and level-shifting substages. Combinational logic executed in input substage. During low half of clock cycle, result of logic operation transmitted to following stage.

Characterization and Modeling of High Power Microwave Effects in CMOS Microelectronics

DTIC Science & Technology

2010-01-01

margin measurement 28 Any voltage above the line marked VIH is considered a valid logic high on the input of the gate. VIH and VIL are defined...can handle any voltage noise level at the input up to VIL without changing state. The region in between VIL and VIH is considered an invalid logic...29 Table 2.2: Intrinsic device characteristics derived from SPETCRE simulations   VIH  (V)  VIL (V)  High Noise Margin  (V)  Low Noise Margin (V

Characterization testing of Lockheed Martin high-power micro pulse tube cryocooler

NASA Astrophysics Data System (ADS)

McKinley, I. M.; Hummel, C. D.; Johnson, D. L.; Rodriguez, J. I.

2017-12-01

This paper describes the thermal vacuum, microphonics, magnetics, and radiation testing and results of a Lockheed Martin high-power micro pulse tube cryocooler. The thermal performance of the microcooler was measured in vacuum for heat reject temperatures between 185 and 300 K. The cooler was driven with a Chroma 61602 AC power source for input powers ranging from 10 to 60 W and drive frequency between 115 and 140 Hz during thermal performance testing. The optimal drive frequency was dependent on both input power and heat reject temperature. In addition, the microphonics of the cooler were measured with the cooler driven by Iris Technologies LCCE-2 and HP-LCCE drive electronics for input powers ranging from 10 to 60 W and drive frequency between 135 and 145 Hz. The exported forces were strongly dependent on input power while only weakly dependent on the drive frequency. Moreover, the exported force in the compressor axis was minimized by closed loop control with the HP-LCCE. The cooler also survived a 500 krad radiation dose while being continuously operated with 30 W of input power at 220 K heat rejection temperature in vacuum. Finally, the DC and AC magnetic fields around the cooler were measured at various locations.

Spectral Changes in Metal Halide and High-pressure Sodium Lamps Equipped with Electronic Dimming

NASA Technical Reports Server (NTRS)

Bubenheim, David L.; Sargis, Raman; Wilson, David

1995-01-01

Electronic dimming of high-intensity discharge lamps offers control of photosynthetic photon flux (PPF) but is often characterized as causing significant spectral changes. Growth chambers with 400-W metal halide (MH) and high-pressure sodium (HPS) lamps were equipped with a dimmer system using silicon-controlled rectifiers (SCR) as high-speed switches. Phase control operation turned the line power off for some period of the alternating current cycle. At full power, the electrical input to HPS and MH lamps was 480 W (root mean squared) and could be decreased to 267 W and 428 W, respectively, before the arc was extinguished. Concomitant with this decrease in input power, PPF decreased by 60% in HPS and 50% in MH. The HPS lamp has characteristic spectral peaks at 589 and 595 nm. As power to the HPS lamps was decreased, the 589-nm peak remained constant while the 595-nm peak decreased, equaling the 589-nm peak at 345-W input, and the 589-nm peak was almost absent at 270-W input. The MH lamp has a broader spectral output but also has a peak at 589 nm and another smaller peak at 545 nm. As input power to the MH lamps decreased, the peak at 589 diminished to equal the 545-nm peak. As input power approached 428 W, the 589-nm peak shifted to 570 nm. While the spectrum changed as input power was decreased in the MH and HPS lamps, the phytochrome equilibrium ratio (P(sub fr):P(sub tot)) remains unchanged for both lamp types.

Comprehensive evaluation of power grid enterprises' credit rating under the reform of transmission and distribution price

NASA Astrophysics Data System (ADS)

Wang, Yongli; Wang, Gang; Zuo, Yi; Fan, Lisha; Wei, Jiaxiang

2017-03-01

On March 15, 2015, the central office issued the "Opinions on Further Deepening the Reform of Electric Power System" (in the 2015 No. 9). This policy marks the central government officially opened a new round of electricity reform. As a programmatic document under the new situation to comprehensively promote the reform of the power system, No. 9 document will be approved as a separate transmission and distribution of electricity prices, which is the first task of promoting the reform of the power system. Grid tariff reform is not only the transmission and distribution price of a separate approval, more of the grid company input-output relationship and many other aspects of deep-level adjustments. Under the background of the reform of the transmission and distribution price, the main factors affecting the input-output relationship, such as the main business, electricity pricing, and investment approval, financial accounting and so on, have changed significantly. The paper designed the comprehensive evaluation index system of power grid enterprises' credit rating under the reform of transmission and distribution price to reduce the impact of the reform on the company's international rating results and the ability to raise funds.

AIRCRAFT REACTOR CONTROL SYSTEM APPLICABLE TO TURBOJET AND TURBOPROP POWER PLANTS

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

Gorker, G.E.

1955-07-19

Control systems proposed for direct cycle nuclear powered aircraft commonly involve control of engine speed, nuclear energy input, and chcmical energy input. A system in which these parameters are controlled by controlling the total energy input, the ratio of nuclear and chemical energy input, and the engine speed is proposed. The system is equally applicable to turbojet or turboprop applications. (auth)

Photon-trapping micro/nanostructures for high linearity in ultra-fast photodiodes

NASA Astrophysics Data System (ADS)

Cansizoglu, Hilal; Gao, Yang; Perez, Cesar Bartolo; Ghandiparsi, Soroush; Ponizovskaya Devine, Ekaterina; Cansizoglu, Mehmet F.; Yamada, Toshishige; Elrefaie, Aly F.; Wang, Shih-Yuan; Islam, M. Saif

2017-08-01

Photodetectors (PDs) in datacom and computer networks where the link length is up to 300 m, need to handle higher than typical input power used in other communication links. Also, to reduce power consumption due to equalization at high speed (>25Gb/s), the datacom links will use PAM-4 signaling instead of NRZ with stringent receiver linearity requirements. Si PDs with photon-trapping micro/nanostructures are shown to have high linearity in output current verses input optical power. Though there is less silicon material due to the holes, the micro-/nanostructured holes collectively reradiate the light to an in-plane direction of the PD surface and can avoid current crowding in the PD. Consequently, the photocurrent per unit volume remains at a low level contributing to high linearity in the photocurrent. We present the effect of design and lattice patterns of micro/nanostructures on the linearity of ultra-fast silicon PDs designed for high speed multi gigabit data networks.

Design and performance study of a DC-DC flyback converter based on wide bandgap power devices for photovoltaic applications

NASA Astrophysics Data System (ADS)

Alharbi, Salah S.; Alharbi, Saleh S.; Al-bayati, Ali M. S.; Matin, Mohammad

2017-08-01

This paper presents a high-performance dc-dc flyback converter design based on wide bandgap (WBG) semiconductor devices for photovoltaic (PV) applications. Two different power devices, a gallium nitride (GaN)-transistor and a silicon (Si)-MOSFET, are implemented individually in the flyback converter to examine their impact on converter performance. The total power loss of the converter with different power devices is analyzed for various switching frequencies. Converter efficiency is evaluated at different switching frequencies, input voltages, and output power levels. The results reveal that the converter with the GaN-transistor has lower total power loss and better efficiency compared to the converter with the conventional Si-MOSFET.

A new RF transmit coil for foot and ankle imaging at 7T MRI.

PubMed

Santini, Tales; Kim, Junghwan; Wood, Sossena; Krishnamurthy, Narayanan; Farhat, Nadim; Maciel, Carlos; Raval, Shailesh B; Zhao, Tiejun; Ibrahim, Tamer S

2018-01-01

A four-channel Tic-Tac-Toe (TTT) transmit RF coil was designed and constructed for foot and ankle imaging at 7T MRI. Numerical simulations using an in-house developed FDTD package and experimental analyses using a homogenous phantom show an excellent agreement in terms of B 1 + field distribution and s-parameters. Simulations performed on an anatomically detailed human lower leg model demonstrated an B 1 + field distribution with a coefficient of variation (CV) of 23.9%/15.6%/28.8% and average B 1 + of 0.33μT/0.56μT/0.43μT for 1W input power (i.e., 0.25W per channel) in the ankle/calcaneus/mid foot respectively. In-vivo B 1 + mapping shows an average B 1 + of 0.29μT over the entire foot/ankle. This newly developed RF coil also presents acceptable levels of average SAR (0.07W/kg for 10g per 1W of input power) and peak SAR (0.34W/kg for 10g per 1W of input power) over the whole lower leg. Preliminary in-vivo images in the foot/ankle were acquired using the T2-DESS MRI sequence without the use of a dedicated receive-only array. Copyright © 2017. Published by Elsevier Inc.

Hollow cathode heater development for the Space Station plasma contactor

NASA Technical Reports Server (NTRS)

Soulas, George C.

1993-01-01

A hollow cathode-based plasma contactor has been selected for use on the Space Station. During the operation of the plasma contactor, the hollow cathode heater will endure approximately 12000 thermal cycles. Since a hollow cathode heater failure would result in a plasma contactor failure, a hollow cathode heater development program was established to produce a reliable heater design. The development program includes the heater design, process documents for both heater fabrication and assembly, and heater testing. The heater design was a modification of a sheathed ion thruster cathode heater. Three heaters have been tested to date using direct current power supplies. Performance testing was conducted to determine input current and power requirements for achieving activation and ignition temperatures, single unit operational repeatability, and unit-to-unit operational repeatability. Comparisons of performance testing data at the ignition input current level for the three heaters show the unit-to-unit repeatability of input power and tube temperature near the cathode tip to be within 3.5 W and 44 degrees C, respectively. Cyclic testing was then conducted to evaluate reliability under thermal cycling. The first heater, although damaged during assembly, completed 5985 ignition cycles before failing. Two additional heaters were subsequently fabricated and have completed 3178 cycles to date in an on-going test.

Ka-Band TWT High-Efficiency Power Combiner for High-Rate Data Transmission

NASA Technical Reports Server (NTRS)

Wintucky, Edwin G.; Simons, Rainee; Vaden, Karl R.; Lesny, Gary G.; Glass, Jeffrey L.

2007-01-01

A four-port magic-T hybrid waveguide junction serves as the central component of a high-efficiency two-way power combiner circuit for transmitting a high-rate phase-modulated digital signal at a carrier frequency in the Ka-band (between 27 and 40 GHz). This power combiner was developed to satisfy a specific requirement to efficiently combine the coherent outputs of two traveling-wavetube (TWT) amplifiers that are typically characterized by power levels on the order of 100 W or more. In this application, the use of a waveguide-based power combiner (instead of a coaxial-cable- or microstrip-based power combiner, for example) is dictated by requirements for low loss, high power-handling capability, and broadband response. Combiner efficiencies were typically 90 percent or more over both the linear and saturated output power regions of operation of the TWTs . Figure 1 depicts the basic configuration of the magic-T hybrid junction. The coherent outputs of the two TWTs enter through ports 1 and 4. As a result of the orientations of the electromagnetic fields, which also provides a needed high port-to-port isolation, of these two input signals and the interior design of the magic-T junction, the input powers are divided so as to add in phase at one output port (port 2), and to be opposite in phase and hence cancel each other at the opposite coplanar output port (port 3). The net result is that the output power at port 2 is essentially double that of the output of one TWT, minus the power lost in the magic-T hybrid junction. Optimum performance as a high-efficiency power combiner thus requires a balance of both power and phase at the input ports of the magic-T. Replicas of this two-way combiner can be arranged in a binary configuration to obtain a 2n-way (where n is an integer) combiner. For example, Figure 2 illustrates the use of three two-way combiners to combine the outputs of four TWTs.

Properties of Miniature Cantilever-Type Ultrasonic Motor Using Lead-Free Array-Type Multilayer Piezoelectric Ceramics of (Sr,Ca)2NaNb5O15 under High Input Power

NASA Astrophysics Data System (ADS)

Doshida, Yutaka; Shimizu, Hiroyuki; Mizuno, Youich; Tamura, Hideki

2012-07-01

The properties of miniature cantilever-type ultrasonic motors using lead-free array-type multilayer piezoelectric ceramics of (Sr,Ca)2NaNb5O15 (SCNN) developed using the design rule were investigated under high input power by comparison with the high-power properties of SCNN ceramics. The frequency dependence of the revolution speed reflected the nonlinear behavior of SCNN ceramics with the hard-spring effect and showed a mirror-reversed image relative to that of the motor of Pb(Zr,Ti)O3 (PZT) ceramics. The output power increased linearly with increasing input power up to 110 mW without heat generation, and the driving properties were almost the same as the expectations under low input power. The output power density characteristics of the motors were high in comparison with those of the commercialized motors of PZT ceramics. It appeared that the motors have a high potential as an environmental friendly piezoelectric device with excellent properties, reflecting the high-power properties of SCNN ceramics.

A 5 nW Quasi-Linear CMOS Hot-Electron Injector for Self-Powered Monitoring of Biomechanical Strain Variations.

PubMed

Zhou, Liang; Abraham, Adam C; Tang, Simon Y; Chakrabartty, Shantanu

2016-12-01

Piezoelectricity-driven hot-electron injectors (p-HEI) are used for self-powered monitoring of mechanical activity in biomechanical implants and structures. Previously reported p-HEI devices operate by harvesting energy from a piezoelectric transducer to generate current and voltage references which are then used for initiating and controlling the process of hot-electron injection. As a result, the minimum energy required to activate the device is limited by the power requirements of the reference circuits. In this paper we present a p-HEI device that operates by directly exploiting the self-limiting capability of an energy transducer when driving the process of hot-electron injection in a pMOS floating-gate transistor. As a result, the p-HEI device can activate itself at input power levels less than 5 nW. Using a prototype fabricated in a 0.5- [Formula: see text] bulk CMOS process we validate the functionality of the proposed injector and show that for a fixed input power, its dynamics is quasi-linear with respect to time. The paper also presents measurement results using a cadaver phantom where the fabricated p-HEI device has been integrated with a piezoelectric transducer and is used for self-powered monitoring of mechanical activity.

Probabilistic Density Function Method for Stochastic ODEs of Power Systems with Uncertain Power Input

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

Wang, Peng; Barajas-Solano, David A.; Constantinescu, Emil

Wind and solar power generators are commonly described by a system of stochastic ordinary differential equations (SODEs) where random input parameters represent uncertainty in wind and solar energy. The existing methods for SODEs are mostly limited to delta-correlated random parameters (white noise). Here we use the Probability Density Function (PDF) method for deriving a closed-form deterministic partial differential equation (PDE) for the joint probability density function of the SODEs describing a power generator with time-correlated power input. The resulting PDE is solved numerically. A good agreement with Monte Carlo Simulations shows accuracy of the PDF method.

Nested-cone transformer antenna

DOEpatents

Ekdahl, C.A.

1991-05-28

A plurality of conical transmission lines are concentrically nested to form an output antenna for pulsed-power, radio-frequency, and microwave sources. The diverging conical conductors enable a high power input density across a bulk dielectric to be reduced below a breakdown power density at the antenna interface with the transmitting medium. The plurality of cones maintain a spacing between conductors which minimizes the generation of high order modes between the conductors. Further, the power input feeds are isolated at the input while enabling the output electromagnetic waves to add at the transmission interface. Thus, very large power signals from a pulse rf, or microwave source can be radiated. 6 figures.

Nested-cone transformer antenna

DOEpatents

Ekdahl, Carl A.

1991-01-01

A plurality of conical transmission lines are concentrically nested to form n output antenna for pulsed-power, radio-frequency, and microwave sources. The diverging conical conductors enable a high power input density across a bulk dielectric to be reduced below a breakdown power density at the antenna interface with the transmitting medium. The plurality of cones maintain a spacing between conductors which minimizes the generation of high order modes between the conductors. Further, the power input feeds are isolated at the input while enabling the output electromagnetic waves to add at the transmission interface. Thus, very large power signals from a pulse rf, or microwave source can be radiated.

System and method to determine electric motor efficiency nonintrusively

DOEpatents

Lu, Bin [Kenosha, WI; Habetler, Thomas G [Snellville, GA; Harley, Ronald G [Lawrenceville, GA

2011-08-30

A system and method for nonintrusively determining electric motor efficiency includes a processor programed to, while the motor is in operation, determine a plurality of stator input currents, electrical input data, a rotor speed, a value of stator resistance, and an efficiency of the motor based on the determined rotor speed, the value of stator resistance, the plurality of stator input currents, and the electrical input data. The determination of the rotor speed is based on one of the input power and the plurality of stator input currents. The determination of the value of the stator resistance is based on at least one of a horsepower rating and a combination of the plurality of stator input currents and the electrical input data. The electrical input data includes at least one of an input power and a plurality of stator input voltages.

Investigation of an X-band gigawatt long pulse multi-beam relativistic klystron amplifier

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

Liu, Zhenbang; Huang, Hua; Lei, Lurong

2015-09-15

To achieve a gigawatt-level long pulse radiation power in X-band, a multi-beam relativistic klystron amplifier is proposed and studied experimentally. By introducing 18 electron drift tubes and extended interaction cavities, the power capacity of the device is increased. A radiation power of 1.23 GW with efficiency of 41% and amplifier gain of 46 dB is obtained in the particle-in-cell simulation. Under conditions of a 10 Hz repeat frequency and an input RF power of 30 kW, a radiation power of 0.9 GW, frequency of 9.405 GHz, pulse duration of 105 ns, and efficiency of 30% is generated in the experiment, and the amplifier gain is aboutmore » 45 dB. Both the simulation and the experiment prove that the multi-beam relativistic klystron amplifier can generate a long pulse GW-level radiation power in X-band.« less

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

Kung, C. C.; Kramer, G. J.; Johnson, E.

Reflectometry, which uses the microwave radar technique to probe the magnetically confined fusion plasmas, is a very powerful tool to observe the density fluctuations in the fusion plasmas. Typically, two or more microwave beams of different frequencies are used to study the plasma density fluctuations. The frequency separation between these two beams of the PPPL designed reflectometer system upgrade on the DIII-D tokamak can be varied over 18 GHz. Due to the performance of the associated electronics, the local oscillator (LO) power level at the LO port of the I/Q demodulator suffers more than 12 dB of power fluctuations whenmore » the frequency separation is varied. Thus, the I/Q demodulator performance is impaired. In order to correct this problem, a power leveling circuit is introduced in the PPPL upgrade. According to the test results, the LO power fluctuation was regulated to be within 1 dB for greater than 16 dB of input power variation over the full dynamic bandwidth of the receiver.« less

The series-elastic shock absorber: tendons attenuate muscle power during eccentric actions.

PubMed

Roberts, Thomas J; Azizi, Emanuel

2010-08-01

Elastic tendons can act as muscle power amplifiers or energy-conserving springs during locomotion. We used an in situ muscle-tendon preparation to examine the mechanical function of tendons during lengthening contractions, when muscles absorb energy. Force, length, and power were measured in the lateral gastrocnemius muscle of wild turkeys. Sonomicrometry was used to measure muscle fascicle length independently from muscle-tendon unit (MTU) length, as measured by a muscle lever system (servomotor). A series of ramp stretches of varying velocities was applied to the MTU in fully activated muscles. Fascicle length changes were decoupled from length changes imposed on the MTU by the servomotor. Under most conditions, muscle fascicles shortened on average, while the MTU lengthened. Energy input to the MTU during the fastest lengthenings was -54.4 J/kg, while estimated work input to the muscle fascicles during this period was only -11.24 J/kg. This discrepancy indicates that energy was first absorbed by elastic elements, then released to do work on muscle fascicles after the lengthening phase of the contraction. The temporary storage of energy by elastic elements also resulted in a significant attenuation of power input to the muscle fascicles. At the fastest lengthening rates, peak instantaneous power input to the MTU reached -2,143.9 W/kg, while peak power input to the fascicles was only -557.6 W/kg. These results demonstrate that tendons may act as mechanical buffers by limiting peak muscle forces, lengthening rates, and power inputs during energy-absorbing contractions.

Optimization of Multi-Fidelity Computer Experiments via the EQIE Criterion

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

He, Xu; Tuo, Rui; Jeff Wu, C. F.

Computer experiments based on mathematical models are powerful tools for understanding physical processes. This article addresses the problem of kriging-based optimization for deterministic computer experiments with tunable accuracy. Our approach is to use multi- delity computer experiments with increasing accuracy levels and a nonstationary Gaussian process model. We propose an optimization scheme that sequentially adds new computer runs by following two criteria. The first criterion, called EQI, scores candidate inputs with given level of accuracy, and the second criterion, called EQIE, scores candidate combinations of inputs and accuracy. Here, from simulation results and a real example using finite element analysis,more » our method out-performs the expected improvement (EI) criterion which works for single-accuracy experiments.« less

Optimization of Multi-Fidelity Computer Experiments via the EQIE Criterion

DOE PAGES

He, Xu; Tuo, Rui; Jeff Wu, C. F.

2017-01-31

Computer experiments based on mathematical models are powerful tools for understanding physical processes. This article addresses the problem of kriging-based optimization for deterministic computer experiments with tunable accuracy. Our approach is to use multi- delity computer experiments with increasing accuracy levels and a nonstationary Gaussian process model. We propose an optimization scheme that sequentially adds new computer runs by following two criteria. The first criterion, called EQI, scores candidate inputs with given level of accuracy, and the second criterion, called EQIE, scores candidate combinations of inputs and accuracy. Here, from simulation results and a real example using finite element analysis,more » our method out-performs the expected improvement (EI) criterion which works for single-accuracy experiments.« less

Experimental investigation of conical bubble structure and acoustic flow structure in ultrasonic field.

PubMed

Ma, Xiaojian; Huang, Biao; Wang, Guoyu; Zhang, Mindi

2017-01-01

The objective of this paper is to investigate the transient conical bubble structure (CBS) and acoustic flow structure in ultrasonic field. In the experiment, the high-speed video and particle image velocimetry (PIV) techniques are used to measure the acoustic cavitation patterns, as well as the flow velocity and vorticity fields. Results are presented for a high power ultrasound with a frequency of 18kHz, and the range of the input power is from 50W to 250W. The results of the experiment show the input power significantly affects the structures of CBS, with the increase of input power, the cavity region of CBS and the velocity of bubbles increase evidently. For the transient motion of bubbles on radiating surface, two different types could be classified, namely the formation, aggregation and coalescence of cavitation bubbles, and the aggregation, shrink, expansion and collapse of bubble cluster. Furthermore, the thickness of turbulent boundary layer near the sonotrode region is found to be much thicker, and the turbulent intensities are much higher for relatively higher input power. The vorticity distribution is prominently affected by the spatial position and input power. Copyright © 2016 Elsevier B.V. All rights reserved.

Quantitative investigation of hydraulic mixing energy input during batch mode anaerobic digestion and its impact on performance.

PubMed

McLeod, James; Othman, Maazuza Z; Parthasarathy, Rajarathinam

2018-05-26

The relationship between mixing energy input and biogas production was investigated by anaerobically digesting sewage sludge in lab scale, hydraulically mixed, batch mode digesters at six different specific energy inputs. The goal was to identify how mixing energy influenced digestion performance at quantitative levels to help explain the varying results in other published works. The results showed that digester homogeneity was largely uninfluenced by energy input, whereas cumulative biogas production and solids destruction were. With similar solids distributions between conditions, the observed differences were attributed to shear forces disrupting substrate-microbe flocs rather than the formation of temperature and/or concentration gradients. Disruption of the substrate-microbe flocs produced less favourable conditions for hydrolytic bacteria, resulting in less production of biomass and more biogas. Overall, this hypothesis explains the current body of research including the inhibitory conditions reported at extreme mixing power inputs. However, further work is required to definitively prove it. Copyright © 2018 Elsevier Ltd. All rights reserved.

Thales Cryogenics rotary cryocoolers for HOT applications

NASA Astrophysics Data System (ADS)

Martin, Jean-Yves; Cauquil, Jean-Marc; Benschop, Tonny; Freche, Sébastien

2012-06-01

Thales Cryogenics has an extensive background in delivering reliable linear and rotary coolers for military, civil and space programs. Recent work carried out at detector level enable to consider a higher operation temperature for the cooled detectors. This has a direct impact on the cooling power required to the cryocooler. In continuation of the work presented last year, Thales cryogenics has studied the operation and optimization of the rotary cryocoolers at high cold regulation temperature. In this paper, the performances of the Thales Cryogenics rotary cryocoolers at elevated cold regulation temperature will be presented. From these results, some trade-offs can be made to combine correct operation of the cryocooler on all the ambient operational range and maximum efficiency of the cryocooler. These trade-offs and the impact on MTTF of elevated cold regulation temperature will be presented and discussed. In correlation with the increase of the cold operation temperature, the cryocooler input power is significantly decreased. As a consequence, the cooler drive electronics own consumption becomes relatively important and must be reduced in order to minimize global input power to the cooling function (cryocooler and cooler drive electronics). Thales Cryogenics has developed a new drive electronics optimized for low input power requirements. In parallel, improvements on RM1 and RM2 cryocoolers have been defined and implemented. The main impacts on performances of these new designs will be presented. Thales cryogenics is now able to propose an efficient cooling function for application requiring a high cold regulation temperature including a range of tuned rotary coolers.

Investigation of 16 × 10 Gbps DWDM System Based on Optimized Semiconductor Optical Amplifier

NASA Astrophysics Data System (ADS)

Rani, Aruna; Dewra, Sanjeev

2017-08-01

This paper investigates the performance of an optical system based on optimized semiconductor optical amplifier (SOA) at 160 Gbps with 0.8 nm channel spacing. Transmission distances up to 280 km at -30 dBm input signal power and up to 247 km at -32 dBm input signal power with acceptable bit error rate (BER) and Q-factor are examined. It is also analyzed that the transmission distance up to 292 km has been covered at -28 dBm input signal power using Dispersion Shifted (DS)-Normal fiber without any power compensation methods.

High power, high efficiency, continuous-wave supercontinuum generation using standard telecom fibers

NASA Astrophysics Data System (ADS)

Arun, S.; Choudhury, Vishal; Balaswamy, V.; Prakash, Roopa; Supradeepa, V. R.

2018-04-01

We demonstrate a simple module for octave spanning continuous-wave supercontinuum generation using standard telecom fiber. This module can accept any high power Ytterbium-doped fiber laser as input. The input light is transferred into the anomalous dispersion region of the telecom fiber through a cascade of Raman shifts. A recently proposed Raman laser architecture with distributed feedback efficiently performs these Raman conversions. A spectrum spanning over 1000nm(>1 octave) from 880-1900nm is demonstrated. The average power from the supercontinuum is ~34W with a high conversion efficiency of 44%. Input wavelength agility is demonstrated with similar supercontinua over a wide input wavelength range.

Power selective optical filter devices and optical systems using same

DOEpatents

Koplow, Jeffrey P

2014-10-07

In an embodiment, a power selective optical filter device includes an input polarizer for selectively transmitting an input signal. The device includes a wave-plate structure positioned to receive the input signal, which includes at least one substantially zero-order, zero-wave plate. The zero-order, zero-wave plate is configured to alter a polarization state of the input signal passing in a manner that depends on the power of the input signal. The zero-order, zero-wave plate includes an entry and exit wave plate each having a fast axis, with the fast axes oriented substantially perpendicular to each other. Each entry wave plate is oriented relative to a transmission axis of the input polarizer at a respective angle. An output polarizer is positioned to receive a signal output from the wave-plate structure and selectively transmits the signal based on the polarization state.

On-Chip Power-Combining for High-Power Schottky Diode Based Frequency Multipliers

NASA Technical Reports Server (NTRS)

Siles Perez, Jose Vicente (Inventor); Chattopadhyay, Goutam (Inventor); Lee, Choonsup (Inventor); Schlecht, Erich T. (Inventor); Jung-Kubiak, Cecile D. (Inventor); Mehdi, Imran (Inventor)

2015-01-01

A novel MMIC on-chip power-combined frequency multiplier device and a method of fabricating the same, comprising two or more multiplying structures integrated on a single chip, wherein each of the integrated multiplying structures are electrically identical and each of the multiplying structures include one input antenna (E-probe) for receiving an input signal in the millimeter-wave, submillimeter-wave or terahertz frequency range inputted on the chip, a stripline based input matching network electrically connecting the input antennas to two or more Schottky diodes in a balanced configuration, two or more Schottky diodes that are used as nonlinear semiconductor devices to generate harmonics out of the input signal and produce the multiplied output signal, stripline based output matching networks for transmitting the output signal from the Schottky diodes to an output antenna, and an output antenna (E-probe) for transmitting the output signal off the chip into the output waveguide transmission line.

Use of a Geothermal-Solar Hybrid Power Plant to Mitigate Declines in Geothermal Resource Productivity

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

Dan Wendt; Greg Mines

2014-09-01

Many, if not all, geothermal resources are subject to decreasing productivity manifested in the form of decreasing brine temperature, flow rate, or both during the life span of the associated power generation project. The impacts of resource productivity decline on power plant performance can be significant; a reduction in heat input to a power plant not only decreases the thermal energy available for conversion to electrical power, but also adversely impacts the power plant conversion efficiency. The reduction in power generation is directly correlated to a reduction in revenues from power sales. Further, projects with Power Purchase Agreement (PPA) contractsmore » in place may be subject to significant economic penalties if power generation falls below the default level specified. A potential solution to restoring the performance of a power plant operating from a declining productivity geothermal resource involves the use of solar thermal energy to restore the thermal input to the geothermal power plant. There are numerous technical merits associated with a renewable geothermal-solar hybrid plant in which the two heat sources share a common power block. The geo-solar hybrid plant could provide a better match to typical electrical power demand profiles than a stand-alone geothermal plant. The hybrid plant could also eliminate the stand-alone concentrated solar power plant thermal storage requirement for operation during times of low or no solar insolation. This paper identifies hybrid plant configurations and economic conditions for which solar thermal retrofit of a geothermal power plant could improve project economics. The net present value of the concentrated solar thermal retrofit of an air-cooled binary geothermal plant is presented as functions of both solar collector array cost and electricity sales price.« less

Lower power dc arcjet operations with hydrogen hydrogen/nitrogen propellant mixtures

NASA Technical Reports Server (NTRS)

Curran, F. M.; Nakanishi, S.

1986-01-01

The arcjet assembly from a flight model system was modified with a new thoriated tungsten nozzle insert and has been tested with hydrogen-nitrogen mixtures simulating the decomposition products of ammonia and hydrazine. Arcjet power consumption ranged from 0.7 to 1.15 kW depending on low rate, input current, and mixture composition. At a nominal 1 kW power level the ammonia mixtures thrust efficiency was about 0.31 at specific impulse values ranging between 460 and 500 sec. Hydrazine mixtures gave similar thrust efficiencies at the same power level with specific impulse values between 395 and 430 sec. Large, spontaneous voltage mode changes were not observed once the thruster had passed a period of instability immediately following start up. This period of instability, and the startup at low pressure, were seen as major causes of constrictor damage during the tests.

Power-control switch

NASA Technical Reports Server (NTRS)

Kessler, L. L.

1976-01-01

Constant-current source creates drive current independent of input-voltage variations, 50% reduction in power loss in base drive circuitry, maintains essentially constant charge rate, and improves rise-time consistency over input voltage range.

Investigation of poly(γ-glutamic acid) production via online determination of viscosity and oxygen transfer rate in shake flasks.

PubMed

Regestein Née Meissner, Lena; Arndt, Julia; Palmen, Thomas G; Jestel, Tim; Mitsunaga, Hitoshi; Fukusaki, Eiichiro; Büchs, Jochen

2017-01-01

Poly(γ-glutamic acid) (γ-PGA) is a biopolymer with many useful properties making it applicable for instance in food and skin care industries, in wastewater treatment, in biodegradable plastics or in the pharmaceutical industry. γ-PGA is usually produced microbially by different Bacillus spp. The produced γ-PGA increases the viscosity of the fermentation broth. In case of shake flask fermentations, this results in an increase of the volumetric power input. The power input in shake flasks can be determined by measuring the torque of an orbitally rotating lab shaker. The online measurement of the volumetric power input enables to continuously monitor the formation or degradation of viscous products like γ-PGA. Combined with the online measurement of the oxygen transfer rate (OTR), the respiration activity of the organisms can be observed at the same time. Two different Bacillus licheniformis strains and three medium compositions were investigated using online volumetric power input and OTR measurements as well as thorough offline analysis. The online volumetric power input measurement clearly depicted changes in γ-PGA formation due to different medium compositions as well as differences in the production behavior of the two investigated strains. A higher citric acid concentration and the addition of trace elements to the standard medium showed a positive influence on γ-PGA production. The online power input signal was used to derive an online viscosity signal which was validated with offline determined viscosity values. The online measurement of the OTR proved to be a valuable tool to follow the respiration activity of the cultivated strains and to determine its reproducibility under different cultivation conditions. The combination of the volumetric power input and the OTR allows for an easy and reliable investigation of new strains, cultivation conditions and medium compositions for their potential in γ-PGA production. The power input signal and the derived online viscosity directly reflect changes in γ-PGA molecular weight and concentration, respectively, due to different cultivation conditions or production strains.

Performance Characteristics of the NEXT Long-Duration Test After 16,550 h and 337 kg of Xenon Processed

NASA Technical Reports Server (NTRS)

Soulas, George C.; Patterson, Michael J.; Herman, Daniel A.

2009-01-01

The NASA s Evolutionary Xenon Thruster (NEXT) program is developing the next-generation ion propulsion system with significant enhancements beyond the state-of-the-art in ion propulsion to provide future NASA science missions with enhanced mission capabilities at a low total development cost. As part of a comprehensive thruster service life assessment utilizing both testing and analyses, a Long-Duration Test (LDT) was initiated to verify the NEXT propellant throughput capability to a qualification-level of 450 kg, 1.5 times the anticipated throughput requirement of 300 kg from mission analyses conducted utilizing the NEXT propulsion system. The LDT is being conducted with a modified, flight-representative NEXT engineering model ion thruster, designated EM3. As of June 25, 2008, the thruster has accumulated 16,550 h of operation: the first 13,042 h at the thruster full-input-power of 6.9 kW with 3.52 A beam current and 1800 V beam power supply voltage. Operation since 13,042 h, i.e., the most recent 3,508 h, has been at an input power of 4.7 kW with 3.52 A beam current and 1180 V beam power supply voltage. The thruster has processed 337 kg of xenon (Xe) surpassing the NSTAR propellant throughput demonstrated during the extended life testing of the Deep Space 1 flight spare ion thruster. The NEXT LDT has demonstrated a total impulse of 13.3 106 N s; the highest total impulse ever demonstrated by an ion thruster. Thruster performance tests are conducted periodically over the entire NEXT throttle table with input power ranging 0.5 to 6.9 kW. Thruster performance parameters including thrust, input power, specific impulse, and thruster efficiency have been nominal with little variation to date. This paper presents the performance of the NEXT LDT to date with emphasis on performance variations following throttling of the thruster to the new operating condition and comparison of performance to the NSTAR extended life test.

The series-elastic shock absorber: tendons attenuate muscle power during eccentric actions

PubMed Central

Azizi, Emanuel

2010-01-01

Elastic tendons can act as muscle power amplifiers or energy-conserving springs during locomotion. We used an in situ muscle-tendon preparation to examine the mechanical function of tendons during lengthening contractions, when muscles absorb energy. Force, length, and power were measured in the lateral gastrocnemius muscle of wild turkeys. Sonomicrometry was used to measure muscle fascicle length independently from muscle-tendon unit (MTU) length, as measured by a muscle lever system (servomotor). A series of ramp stretches of varying velocities was applied to the MTU in fully activated muscles. Fascicle length changes were decoupled from length changes imposed on the MTU by the servomotor. Under most conditions, muscle fascicles shortened on average, while the MTU lengthened. Energy input to the MTU during the fastest lengthenings was −54.4 J/kg, while estimated work input to the muscle fascicles during this period was only −11.24 J/kg. This discrepancy indicates that energy was first absorbed by elastic elements, then released to do work on muscle fascicles after the lengthening phase of the contraction. The temporary storage of energy by elastic elements also resulted in a significant attenuation of power input to the muscle fascicles. At the fastest lengthening rates, peak instantaneous power input to the MTU reached −2,143.9 W/kg, while peak power input to the fascicles was only −557.6 W/kg. These results demonstrate that tendons may act as mechanical buffers by limiting peak muscle forces, lengthening rates, and power inputs during energy-absorbing contractions. PMID:20507964

OAST Space Theme Workshop. Volume 3: Working group summary. 6: Power (P-2). A. Statement. B. Technology needs (form 1). C. Priority assessment (form 2)

NASA Technical Reports Server (NTRS)

1976-01-01

Power requirements for the multipurpose space power platform, for space industrialization, SETI, the solar system exploration facility, and for global services are assessed for various launch dates. Priorities and initiatives for the development of elements of space power systems are described for systems using light power input (solar energy source) or thermal power input, (solar, chemical, nuclear, radioisotopes, reactors). Systems for power conversion, power processing, distribution and control are likewise examined.

Preliminary design for a reverse Brayton cycle cryogenic cooler

NASA Technical Reports Server (NTRS)

Swift, Walter L.

1993-01-01

A long life, single stage, reverse Brayton cycle cryogenic cooler is being developed for applications in space. The system is designed to provide 5 W of cooling at a temperature of 65 Kelvin with a total cycle input power of less than 200 watts. Key features of the approach include high speed, miniature turbomachines; an all metal, high performance, compact heat exchanger; and a simple, high frequency, three phase motor drive. In Phase 1, a preliminary design of the system was performed. Analyses and trade studies were used to establish the thermodynamic performance of the system and the performance specifications for individual components. Key mechanical features for components were defined and assembly layouts for the components and the system were prepared. Critical materials and processes were identified. Component and brassboard system level tests were conducted at cryogenic temperatures. The system met the cooling requirement of 5 W at 65 K. The system was also operated over a range of cooling loads from 0.5 W at 37 K to 10 W at 65 K. Input power to the system was higher than target values. The heat exchanger and inverter met or exceeded their respective performance targets. The compresssor/motor assembly was marginally below its performance target. The turboexpander met its aerodynamic efficiency target, but overall performance was below target because of excessive heat leak. The heat leak will be reduced to an acceptable value in the engineering model. The results of Phase 1 indicate that the 200 watt input power requirement can be met with state-of-the-art technology in a system which has very flexible integration requirements and negligible vibration levels.

Preliminary design for a reverse Brayton cycle cryogenic cooler

NASA Astrophysics Data System (ADS)

Swift, Walter L.

1993-12-01

A long life, single stage, reverse Brayton cycle cryogenic cooler is being developed for applications in space. The system is designed to provide 5 W of cooling at a temperature of 65 Kelvin with a total cycle input power of less than 200 watts. Key features of the approach include high speed, miniature turbomachines; an all metal, high performance, compact heat exchanger; and a simple, high frequency, three phase motor drive. In Phase 1, a preliminary design of the system was performed. Analyses and trade studies were used to establish the thermodynamic performance of the system and the performance specifications for individual components. Key mechanical features for components were defined and assembly layouts for the components and the system were prepared. Critical materials and processes were identified. Component and brassboard system level tests were conducted at cryogenic temperatures. The system met the cooling requirement of 5 W at 65 K. The system was also operated over a range of cooling loads from 0.5 W at 37 K to 10 W at 65 K. Input power to the system was higher than target values. The heat exchanger and inverter met or exceeded their respective performance targets. The compresssor/motor assembly was marginally below its performance target. The turboexpander met its aerodynamic efficiency target, but overall performance was below target because of excessive heat leak. The heat leak will be reduced to an acceptable value in the engineering model. The results of Phase 1 indicate that the 200 watt input power requirement can be met with state-of-the-art technology in a system which has very flexible integration requirements and negligible vibration levels.

Solid-state repetitive generator with a gyromagnetic nonlinear transmission line operating as a peak power amplifier

NASA Astrophysics Data System (ADS)

Gusev, A. I.; Pedos, M. S.; Rukin, S. N.; Timoshenkov, S. P.

2017-07-01

In this work, experiments were made in which gyromagnetic nonlinear transmission line (NLTL) operates as a peak power amplifier of the input pulse. At such an operating regime, the duration of the input pulse is close to the period of generated oscillations, and the main part of the input pulse energy is transmitted only to the first peak of the oscillations. Power amplification is achieved due to the voltage amplitude of the first peak across the NLTL output exceeding the voltage amplitude of the input pulse. In the experiments, the input pulse with an amplitude of 500 kV and a half-height pulse duration of 7 ns is applied to the NLTL with a natural oscillation frequency of ˜300 MHz. At the output of the NLTL in 40 Ω coaxial transmission line, the pulse amplitude is increased to 740 kV and the pulse duration is reduced to ˜2 ns, which correspond to power amplification of the input pulse from ˜6 to ˜13 GW. As a source of input pulses, a solid-state semiconductor opening switch generator was used, which allowed carrying out experiments at pulse repetition frequency up to 1 kHz in the burst mode of operation.

Design and performance of 10-Gb/s L-band REAM-SOA for OLT Transmitter in next generation access networks.

PubMed

Lee, Dong-Hun; Jeong, Jong Sool; Kim, Ki-Soo; Kim, Hyun-Soo; Kim, Dong Churl; Park, Mi-Ran; Han, Yong-Tak; Kwon, Oh Kee; Kwon, O-Kyun

2015-02-09

We present a 10-Gb/s L-band reflective electro-absorption modulator integrated with a semiconductor optical amplifier (REAM-SOA) having improved transmission performance at very low input power of seed light. To decrease the input power of seed light, the absorption characteristics of the REAM are adjusted to reduce the amplified spontaneous emission light returned into the SOA, suppressing the gain saturation effect of the SOA. At a considerably low input power of -16 dBm, the REAM-SOA exhibits a low transmission penalty of about 1.2 dB after 50-km SMF transmission. Over a wide input power range from -16 dBm to 5 dBm, a penalty of less than 1.6 dB is achieved at 50-km transmission.

Spectral Changes in Metal Halide and High-Pressure Sodium Lamps Equipped with Electronic Dimming

NASA Technical Reports Server (NTRS)

Bubenheim, David L.; Sargis, Raman; Wilson, David

1995-01-01

Electronic dimming of high-intensity discharge lamps offers control of Photosynthetic Photon Flux (PPF) but is often characterized as causing significant spectral changes. Growth chambers with 400-W Metal Halide (MH) and High-Pressure Sodium (HPS) lamps were equipped with a dimmer system using Silicon-Controlled Rectifiers (SCR) as high-speed switches. Phase control operation turned the line power off for some period of the alternating current cycle. At full power, the electrical input to HPS and MH lamps was 480 W (root mean squared) and could be decreased to 267 W and 428 W, respectively, before the arc was extinguished. Concomitant with this decrease in input power, PPF decreased by 60% in HPS and 50% in MH. The HPS lamp has characteristic spectral peaks at 589 and 595 nm. As power to the HPS lamps was decreased, the 589-nm peak remained constant while the 595-nm peak decreased, equaling the 589-nm peak at 345-W input, and 589-nm peak was almost absent at 270-W input. The MH lamp has a broader spectral output but also has a peak at 589 nm and another smaller peak at 545 nm. As input power approached 428 W, the 589-nm peak shifted to 570 nm. While the spectrum changed as input power was decreased in the MH and HPS lamps, the phytochrome equilibrium ratio (P(sub ft):P(sub tot)) remains unchanged for both lamp types.

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

System for detecting and limiting electrical ground faults within electrical devices

DOEpatents

Gaubatz, Donald C.

1990-01-01

An electrical ground fault detection and limitation system for employment with a nuclear reactor utilizing a liquid metal coolant. Elongate electromagnetic pumps submerged within the liquid metal coolant and electrical support equipment experiencing an insulation breakdown occasion the development of electrical ground fault current. Without some form of detection and control, these currents may build to damaging power levels to expose the pump drive components to liquid metal coolant such as sodium with resultant undesirable secondary effects. Such electrical ground fault currents are detected and controlled through the employment of an isolated power input to the pumps and with the use of a ground fault control conductor providing a direct return path from the affected components to the power source. By incorporating a resistance arrangement with the ground fault control conductor, the amount of fault current permitted to flow may be regulated to the extent that the reactor may remain in operation until maintenance may be performed, notwithstanding the existence of the fault. Monitors such as synchronous demodulators may be employed to identify and evaluate fault currents for each phase of a polyphase power, and control input to the submerged pump and associated support equipment.

Performance analysis of electronic power transformer based on neuro-fuzzy controller.

PubMed

Acikgoz, Hakan; Kececioglu, O Fatih; Yildiz, Ceyhun; Gani, Ahmet; Sekkeli, Mustafa

2016-01-01

In recent years, electronic power transformer (EPT), which is also called solid state transformer, has attracted great interest and has been used in place of the conventional power transformers. These transformers have many important functions as high unity power factor, low harmonic distortion, constant DC bus voltage, regulated output voltage and compensation capability. In this study, proposed EPT structure contains a three-phase pulse width modulation rectifier that converts 800 Vrms AC to 2000 V DC bus at input stage, a dual active bridge converter that provides 400 V DC bus with 5:1 high frequency transformer at isolation stage and a three-phase two level inverter that is used to obtain AC output at output stage. In order to enhance dynamic performance of EPT structure, neuro fuzzy controllers which have durable and nonlinear nature are used in input and isolation stages instead of PI controllers. The main aim of EPT structure with the proposed controller is to improve the stability of power system and to provide faster response against disturbances. Moreover, a number of simulation results are carried out to verify EPT structure designed in MATLAB/Simulink environment and to analyze compensation ability for voltage harmonics, voltage flicker and voltage sag/swell conditions.

High power, high efficiency, continuous-wave supercontinuum generation using standard telecom fibers.

PubMed

Arun, S; Choudhury, Vishal; Balaswamy, V; Prakash, Roopa; Supradeepa, V R

2018-04-02

We demonstrate a simple module for octave spanning continuous-wave supercontinuum generation using standard telecom fiber. This module can accept any high power ytterbium-doped fiber laser as input. The input light is transferred into the anomalous dispersion region of the telecom fiber through a cascade of Raman shifts. A recently proposed Raman laser architecture with distributed feedback efficiently performs these Raman conversions. A spectrum spanning over 1000nm (>1 octave) from 880 to 1900nm is demonstrated. The average power from the supercontinuum is ~34W with a high conversion efficiency of 44%. Input wavelength agility is demonstrated with similar supercontinua over a wide input wavelength range.

Femtosecond soliton source with fast and broad spectral tunability.

PubMed

Masip, Martin E; Rieznik, A A; König, Pablo G; Grosz, Diego F; Bragas, Andrea V; Martinez, Oscar E

2009-03-15

We present a complete set of measurements and numerical simulations of a femtosecond soliton source with fast and broad spectral tunability and nearly constant pulse width and average power. Solitons generated in a photonic crystal fiber, at the low-power coupling regime, can be tuned in a broad range of wavelengths, from 850 to 1200 nm using the input power as the control parameter. These solitons keep almost constant time duration (approximately 40 fs) and spectral widths (approximately 20 nm) over the entire measured spectra regardless of input power. Our numerical simulations agree well with measurements and predict a wide working wavelength range and robustness to input parameters.

Straight and chopped dc performance data for a Prestolite MTC-4001 motor and a general electric EV-1 controller

NASA Technical Reports Server (NTRS)

Edie, P. C.

1981-01-01

Performance data on the Prestolite MTC-4001 series wound dc motor and General Electric EV-1 Chopper Controller is supplied for the electric vehicle manufacturer. Data are provided for both straight and chopped dc input to the motor, at 2 motor temperature levels. Testing was done at 6 voltage increments to the motor, and 2 voltage increments to the controller. Data results are presented in both tabular and graphical forms. Tabular information includes motor voltage and current input data, motor speed and torque output data, power data and temperature data. Graphical information includes torque-speed, motor power output-speed, torque-current, and efficiency-speed plots under the various operating conditions. The data resulting from this testing show the speed-torque plots to have the most variance with operating temperature. The maximum motor efficiency is between 76% and 82%, regardless of temperature or mode of operation.

Development of a 1 kW, 200 C Mapham Inventor

NASA Technical Reports Server (NTRS)

Hammoud, Ahmad; Gerber, Scott; Bauman, Eric; Overton, Eric; Myers, Ira; Bercaw, Robert

1995-01-01

Electronic systems and components are often exposed to high temperature environment in space-based applications, nuclear power facilities, and geothermal energy extraction fields. A key requirement for these systems is, therefore, to withstand the high temperature exposure while maintaining efficient and reliable operation. Efforts were taken to design and develop a high temperature power inverter capable of 200 C operation. A 1 kW, 20 kHz Mapham inverter was designed and evaluated as a function of temperature at different load levels. The inverter system, excluding its input, control, and logic circuits, was characterized at temperatures from ambient to 200 C at 0%, 50%, and 100% resistive loading. With an applied input voltage of 75 VDC, the inverter produced an output of 250 VAC. The results obtained, which indicate good operational characteristics of the inverter up to 200 C, are presented and discussed.

Experimental study of the visible-light photocatalytic activity of oxygen-deficient TiO2 prepared with Ar/H2 plasma surface treatment

NASA Astrophysics Data System (ADS)

Nakano, Takuma; Yazawa, Shota; Araki, Shota; Kogoshi, Sumio; Katayama, Noboru; Kudo, Yusuke; Nakanishi, Tetsuya

2015-01-01

Oxygen-deficient TiO2 (TiO2-x) has been proposed as a visible-light-responsive photocatalyst. TiO2-x thin films were prepared by Ar/H2 plasma surface treatment, applying varying levels of microwave input power and processing times. The highest visible light photocatalytic activity was observed when using an input power of 200 W, a plasma processing time of 10 min, and a 1:1 \\text{Ar}:\\text{H}2 ratio, conditions that generate an electron temperature of 5.7(±1.0) eV and an electron density of 8.5 × 1010 cm-3. The maximum formaldehyde (HCHO) removal rate of the TiO2-x film was 2.6 times higher than that obtained from a TiO2-xNx film under the same test conditions.

Signaling mechanisms underlying the robustness and tunability of the plant immune network

PubMed Central

Kim, Yungil; Tsuda, Kenichi; Igarashi, Daisuke; Hillmer, Rachel A.; Sakakibara, Hitoshi; Myers, Chad L.; Katagiri, Fumiaki

2014-01-01

Summary How does robust and tunable behavior emerge in a complex biological network? We sought to understand this for the signaling network controlling pattern-triggered immunity (PTI) in Arabidopsis. A dynamic network model containing four major signaling sectors, the jasmonate, ethylene, PAD4, and salicylate sectors, which together explain up to 80% of the PTI level, was built using data for dynamic sector activities and PTI levels under exhaustive combinatorial sector perturbations. Our regularized multiple regression model had a high level of predictive power and captured known and unexpected signal flows in the network. The sole inhibitory sector in the model, the ethylene sector, was central to the network robustness via its inhibition of the jasmonate sector. The model's multiple input sites linked specific signal input patterns varying in strength and timing to different network response patterns, indicating a mechanism enabling tunability. PMID:24439900

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.

Evidence of charge exchange pumping in calcium-xenon system

NASA Technical Reports Server (NTRS)

Chubb, D. L.

1973-01-01

Charge exchange between xenon ions and calcium atoms may produce an inversion between the 5s or 4d and 4p energy levels of the calcium ions. A low power flowing xenon plasma seeded with calcium was utilized to determine if charge exchange or electron collisions populate the 5s and 4d levels Ca(+). Line intensity ratios proportional to the density ratios n5s/n4p and n4d/n4p were measured. From the dependence of these intensity ratios on power input to the xenon plasma it was concluded that charge exchange pumping of the 5s and 4d levels predominates over electron collisional pumping of these levels. Also, by comparing intensity ratios obtained using argon and krypton in place of xenon with those obtained in xenon the same conclusion was made.

The effect of thermal de-phasing on the beam quality of a high-power single-pass second harmonic generation

NASA Astrophysics Data System (ADS)

Sadat Hashemi, Somayeh; Ghavami Sabouri, Saeed; Khorsandi, Alireza

2018-04-01

We present a theoretical model in order to study the effect of a thermally loaded crystal on the quality of a second-harmonic (SH) beam generated in a high-power pumping regime. The model is provided based on using a particular structure of oven considered for MgO:PPsLT nonlinear crystal to compensate for the thermal de-phasing effect that as the pumping power reaches up to 50 W degrades the conversion efficiency and beam quality of the interacting beams. Hereupon, the quality of fundamental beam is involved in the modeling to investigate the final effect on the beam quality of generated SH beam. Beam quality evaluation is subsequently simulated using Hermite-Gaussian modal decomposition approach for a range of fundamental beam qualities varied from 1 to 3 and for different levels of input powers. To provide a meaningful comparison numerical simulation is correlated with real data deduced from a high-power SH generation (SHG) experimental device. It is found that when using the open-top oven scheme and fixing the fundamental M 2-factor at nearly 1, for a range of input powers changing from 15 to 30 W, the M 2-factor of SHG beam is degraded from 9% to 24%, respectively, confirming very good consistency with the reported experimental results.

State of the NASA Aeropropulsion Discipline Input from the Glenn Research Center

NASA Technical Reports Server (NTRS)

Reddy, D. R.; Schmidt, George

2017-01-01

PROBLEM: Current power turbines are designed for single operating speed, and performance degrades rapidly as power turbine speed decreases. OBJECTIVES: Demonstrate 50 improvement in efficient operational capability using a Variable Speed Power Turbine concept. (Refer to figure lower left, where the goal is to raise efficiency from the current technology line to the green line which represents the AVSPOT VSPT goal.APPROACH: Conduct RD required to advance the technology readiness level of VSPT technology to TRL 4Partner with DoD and leverage DOD AVSPOT contract to share government cost (5050) of contracted efforts to GE and PW for VSPT TRL 45 demonstration.

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

Laros III, James H.; DeBonis, David; Grant, Ryan

Measuring and controlling the power and energy consumption of high performance computing systems by various components in the software stack is an active research area [13, 3, 5, 10, 4, 21, 19, 16, 7, 17, 20, 18, 11, 1, 6, 14, 12]. Implementations in lower level software layers are beginning to emerge in some production systems, which is very welcome. To be most effective, a portable interface to measurement and control features would significantly facilitate participation by all levels of the software stack. We present a proposal for a standard power Application Programming Interface (API) that endeavors to cover themore » entire software space, from generic hardware interfaces to the input from the computer facility manager.« less

Power conditioning unit for photovoltaic power systems

NASA Astrophysics Data System (ADS)

Beghin, G.; Nguyen Phuoc, V. T.

Operational features and components of a power conditioning unit for interconnecting solar cell module powers with a utility grid are outlined. The two-stage unit first modifies the voltage to desired levels on an internal dc link, then inverts the current in 2 power transformers connected to a vector summation control to neutralize harmonic distortion up to the 11th harmonic. The system operates in parallel with the grid with extra inductors to absorb line-to-line voltage and phase differences, and permits peak power use from the PV array. Reactive power is gained internally, and a power system controller monitors voltages, frequencies, and currents. A booster preregulator adjusts the input voltage from the array to provide voltage regulation for the inverter, and can commutate 450 amps. A total harmonic distortion of less than 5 percent is claimed, with a rating of 5 kVA, 50/60 Hz, 3-phase, and 4-wire.

Measured thermal images of a gallium arsenide power MMIC with and without RF applied to the input

NASA Astrophysics Data System (ADS)

Oxley, C. H.; Coaker, B. M.; Priestley, N. E.

2003-04-01

A gallium arsenide microwave monolithic integrated circuit (MMIC) power amplifier (M/ACom type MAAM71100) has been measured using infra-red microscope technology, with and without the application of a RF input signal. A reduction of approximately 10 °C in chip temperature was observed with the application of a RF input signal, which will influence the MTTF of the chip. Further, the measurement technique may be used to monitor the thermal impedance and dynamic cooling of RF power devices under operational conditions in complex circuits.

Allan deviation computations of a linear frequency synthesizer system using frequency domain techniques

NASA Technical Reports Server (NTRS)

Wu, Andy

1995-01-01

Allan Deviation computations of linear frequency synthesizer systems have been reported previously using real-time simulations. Even though it takes less time compared with the actual measurement, it is still very time consuming to compute the Allan Deviation for long sample times with the desired confidence level. Also noises, such as flicker phase noise and flicker frequency noise, can not be simulated precisely. The use of frequency domain techniques can overcome these drawbacks. In this paper the system error model of a fictitious linear frequency synthesizer is developed and its performance using a Cesium (Cs) atomic frequency standard (AFS) as a reference is evaluated using frequency domain techniques. For a linear timing system, the power spectral density at the system output can be computed with known system transfer functions and known power spectral densities from the input noise sources. The resulting power spectral density can then be used to compute the Allan Variance at the system output. Sensitivities of the Allan Variance at the system output to each of its independent input noises are obtained, and they are valuable for design trade-off and trouble-shooting.

How the type of input function affects the dynamic response of conducting polymer actuators

NASA Astrophysics Data System (ADS)

Xiang, Xingcan; Alici, Gursel; Mutlu, Rahim; Li, Weihua

2014-10-01

There has been a growing interest in smart actuators typified by conducting polymer actuators, especially in their (i) fabrication, modeling and control with minimum external data and (ii) applications in bio-inspired devices, robotics and mechatronics. Their control is a challenging research problem due to the complex and nonlinear properties of these actuators, which cannot be predicted accurately. Based on an input-shaping technique, we propose a new method to improve the conducting polymer actuators’ command-following ability, while minimizing their electric power consumption. We applied four input functions with smooth characteristics to a trilayer conducting polymer actuator to experimentally evaluate its command-following ability under an open-loop control strategy and a simulated feedback control strategy, and, more importantly, to quantify how the type of input function affects the dynamic response of this class of actuators. We have found that the four smooth inputs consume less electrical power than sharp inputs such as a step input with discontinuous higher-order derivatives. We also obtained an improved transient response performance from the smooth inputs, especially under the simulated feedback control strategy, which we have proposed previously [X Xiang, R Mutlu, G Alici, and W Li, 2014 “Control of conducting polymer actuators without physical feedback: simulated feedback control approach with particle swarm optimization’, Journal of Smart Materials and Structure, 23]. The idea of using a smooth input command, which results in lower power consumption and better control performance, can be extended to other smart actuators. Consuming less electrical energy or power will have a direct effect on enhancing the operational life of these actuators.

Simulation of electric vehicles with hybrid power systems

NASA Astrophysics Data System (ADS)

Burke, A. F.; Cole, G. H.

Computer programs for the simulation of the operation of electric vehicles with hybrid power systems are described. These programs treat cases in which high energy density ultracapacitors or high power density pulse batteries are used to load level the main energy storage battery in the vehicle. A generalized control strategy for splitting the power between the main battery and the pulse power devices is implemented such that the user can specify the nominal battery power as a function of the state-of-charge of the ultracapacitor or pulse power battery. The programs display graphically on the screen, as they run, the power from both the main battery and the pulse power device and the state-of-charge of the pulse power device. After each run is completed, a summary is printed out from which the effect of load leveling the battery on vehicle range and energy consumption can be determined. Default input files are provided with the programs so various combinations of vehicles, driveline components, and batteries of special current interest to the EV community can be run with either type of pulse power device. Typical simulation results are shown including cases in which the pulse power devices are connected in parallel with the main battery without interface electronics.

Control Board Digital Interface Input Devices – Touchscreen, Trackpad, or Mouse?

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

Thomas A. Ulrich; Ronald L. Boring; Roger Lew

The authors collaborated with a power utility to evaluate input devices for use in the human system interface (HSI) for a new digital Turbine Control System (TCS) at a nuclear power plant (NPP) undergoing a TCS upgrade. A standalone dynamic software simulation of the new digital TCS and a mobile kiosk were developed to conduct an input device study to evaluate operator preference and input device effectiveness. The TCS software presented the anticipated HSI for the TCS and mimicked (i.e., simulated) the turbine systems’ responses to operator commands. Twenty-four licensed operators from the two nuclear power units participated in themore » study. Three input devices were tested: a trackpad, mouse, and touchscreen. The subjective feedback from the survey indicates the operators preferred the touchscreen interface. The operators subjectively rated the touchscreen as the fastest and most comfortable input device given the range of tasks they performed during the study, but also noted a lack of accuracy for selecting small targets. The empirical data suggest the mouse input device provides the most consistent performance for screen navigation and manipulating on screen controls. The trackpad input device was both empirically and subjectively found to be the least effective and least desired input device.« less

Tests of Transport Theory and Reduced Impurity Influx with Highly Radiative Plasmas in TFTR

NASA Astrophysics Data System (ADS)

Hill, K. W.

1997-11-01

The electron and ion temperature profiles in beam-heated plasmas were observed to be remarkably invariant when radiative losses were increased significantly through gas puffing of high-Z impurities (argon, krypton, xenon) in the Tokamak Fusion Test Reactor. Without impurity puffing, radiative losses accounted for typically only ~ 25\\char'45 of the input power and the radiation profile was strongly peaked at the plasma edge, where the dominant carbon impurity was not fully stripped. At central electron temperatures, T_eo, of ~ 6 keV, trace concentrations of krypton and xenon (n_z/ne ~ 10-3) generated flat and centrally peaked radiation profiles respectively, and a significant fraction of the input power (45-100\\char'45 ) was lost through radiation. This loss provided a nearly ideal technique for studying local heat transport in tokamaks because it perturbed the net heating profile strongly and in a measureable way, with little effect on the density and the beam deposition profiles. In supershot plasmas, Ti >> T_e, the ion temperature profile remained constant, or even increased modestly, as the radiated power fraction was increased to 75-90\\char'45 with krypton and xenon. This observation is surprising because ion-electron coupling is the dominant power loss term for the ions in the core of supershot plasmas, and the central Ti would have decreased a factor of two if the local ion thermal diffusivity had remained constant at its value without impurity puffing. In L-mode plasmas where ion-electron power coupling is a smaller term in the power balance, the electron temperature during impurity puffing also changed only ~ 10-15\\char'45 even as the net power flow through the electrons was decreased by a factor of ~ 3. The ``stiffness" of the temperature profiles to net input power is supportive of transport mechanisms which have a marginal-stability character. Preliminary comparisons of the temperature changes with predictions of the IFS/PPPL transport model,(M. Kotschenreuther, W. Dorland, M. A. Beer, and G. W. Hammett, Phys. Plasmas 2, 2381 (1995)) which has strong marginal-stability behavior, are reasonable; more detailed comparisons are in progress. Use of high-Z radiators did not impair fusion performance, confirming they can be used to reduce the heat flux to the plasma facing components with minimal ion dilution. At input power level s of 30-33 MW, enhanced radiation through krypton and xenon puffing eliminated serious carbon influx (carbon ``blooms") which occurred in comparable plasmas without impurity puffing.

Inhibitory Gating of Basolateral Amygdala Inputs to the Prefrontal Cortex

PubMed Central

McGarry, Laura M.

2016-01-01

Interactions between the prefrontal cortex (PFC) and basolateral amygdala (BLA) regulate emotional behaviors. However, a circuit-level understanding of functional connections between these brain regions remains incomplete. The BLA sends prominent glutamatergic projections to the PFC, but the overall influence of these inputs is predominantly inhibitory. Here we combine targeted recordings and optogenetics to examine the synaptic underpinnings of this inhibition in the mouse infralimbic PFC. We find that BLA inputs preferentially target layer 2 corticoamygdala over neighboring corticostriatal neurons. However, these inputs make even stronger connections onto neighboring parvalbumin and somatostatin expressing interneurons. Inhibitory connections from these two populations of interneurons are also much stronger onto corticoamygdala neurons. Consequently, BLA inputs are able to drive robust feedforward inhibition via two parallel interneuron pathways. Moreover, the contributions of these interneurons shift during repetitive activity, due to differences in short-term synaptic dynamics. Thus, parvalbumin interneurons are activated at the start of stimulus trains, whereas somatostatin interneuron activation builds during these trains. Together, these results reveal how the BLA impacts the PFC through a complex interplay of direct excitation and feedforward inhibition. They also highlight the roles of targeted connections onto multiple projection neurons and interneurons in this cortical circuit. Our findings provide a mechanistic understanding for how the BLA can influence the PFC circuit, with important implications for how this circuit participates in the regulation of emotion. SIGNIFICANCE STATEMENT The prefrontal cortex (PFC) and basolateral amygdala (BLA) interact to control emotional behaviors. Here we show that BLA inputs elicit direct excitation and feedforward inhibition of layer 2 projection neurons in infralimbic PFC. BLA inputs are much stronger at corticoamygdala neurons compared with nearby corticostriatal neurons. However, these inputs are even more powerful at parvalbumin and somatostatin expressing interneurons. BLA inputs thus activate two parallel inhibitory networks, whose contributions change during repetitive activity. Finally, connections from these interneurons are also more powerful at corticoamygdala neurons compared with corticostriatal neurons. Together, our results demonstrate how the BLA predominantly inhibits the PFC via a complex sequence involving multiple cell-type and input-specific connections. PMID:27605614

Inhibitory Gating of Basolateral Amygdala Inputs to the Prefrontal Cortex.

PubMed

McGarry, Laura M; Carter, Adam G

2016-09-07

Interactions between the prefrontal cortex (PFC) and basolateral amygdala (BLA) regulate emotional behaviors. However, a circuit-level understanding of functional connections between these brain regions remains incomplete. The BLA sends prominent glutamatergic projections to the PFC, but the overall influence of these inputs is predominantly inhibitory. Here we combine targeted recordings and optogenetics to examine the synaptic underpinnings of this inhibition in the mouse infralimbic PFC. We find that BLA inputs preferentially target layer 2 corticoamygdala over neighboring corticostriatal neurons. However, these inputs make even stronger connections onto neighboring parvalbumin and somatostatin expressing interneurons. Inhibitory connections from these two populations of interneurons are also much stronger onto corticoamygdala neurons. Consequently, BLA inputs are able to drive robust feedforward inhibition via two parallel interneuron pathways. Moreover, the contributions of these interneurons shift during repetitive activity, due to differences in short-term synaptic dynamics. Thus, parvalbumin interneurons are activated at the start of stimulus trains, whereas somatostatin interneuron activation builds during these trains. Together, these results reveal how the BLA impacts the PFC through a complex interplay of direct excitation and feedforward inhibition. They also highlight the roles of targeted connections onto multiple projection neurons and interneurons in this cortical circuit. Our findings provide a mechanistic understanding for how the BLA can influence the PFC circuit, with important implications for how this circuit participates in the regulation of emotion. The prefrontal cortex (PFC) and basolateral amygdala (BLA) interact to control emotional behaviors. Here we show that BLA inputs elicit direct excitation and feedforward inhibition of layer 2 projection neurons in infralimbic PFC. BLA inputs are much stronger at corticoamygdala neurons compared with nearby corticostriatal neurons. However, these inputs are even more powerful at parvalbumin and somatostatin expressing interneurons. BLA inputs thus activate two parallel inhibitory networks, whose contributions change during repetitive activity. Finally, connections from these interneurons are also more powerful at corticoamygdala neurons compared with corticostriatal neurons. Together, our results demonstrate how the BLA predominantly inhibits the PFC via a complex sequence involving multiple cell-type and input-specific connections. Copyright © 2016 the authors 0270-6474/16/369391-16$15.00/0.

Proton-decoupled, Overhauser-enhanced, spatially localized carbon-13 spectroscopy in humans.

PubMed

Bottomley, P A; Hardy, C J; Roemer, P B; Mueller, O M

1989-12-01

Spatially localized, natural abundance, carbon (13C) NMR spectroscopy has been combined with proton (1H) decoupling and nuclear Overhauser enhancement to improve 13C sensitivity up to five-fold in the human leg, liver, and heart. Broadhand-decoupled 13C spectra were acquired in 1 s to 17 min with a conventional 1.5-T imaging/spectroscopy system, an auxiliary 1H decoupler, an air-cooled dual-coil coplanar surface probe, and both depth-resolved surface coil spectroscopy (DRESS) and one-dimensional phase-encoding gradient NMR pulse sequences. The surface coil probe comprised circular and figure-eight-shaped coils to eliminate problems with mutual coupling of coils at high decoupling power levels applied during 13C reception. Peak decoupler RF power deposition in tissue was computed numerically from electromagnetic theory assuming a semi-infinite plane of uniform biological conductor. Peak values at the surface were calculated at 4 to 6 W/kg in any gram of tissue for each watt of decoupler power input excluding all coil and cable losses, warning of potential local RF heating problems in these and related experiments. The average power deposition was about 9 mW/kg per watt input, which should present no systemic hazard. At 3 W input, human 13C spectra were decoupled to a depth of about 5 cm while some Overhauser enhancement was sustained up to about 3 cm depth, without ill effect. The observation of glycogen in localized natural abundance 13C spectra of heart and muscle suggests that metabolites in the citric acid cycle should be observable noninvasively using 13C-labeled substrates.

Carbon emissions and resources use by Chinese economy 2007: A 135-sector inventory and input-output embodiment

NASA Astrophysics Data System (ADS)

Chen, G. Q.; Chen, Z. M.

2010-11-01

A 135-sector inventory and embodiment analysis for carbon emissions and resources use by Chinese economy 2007 is presented in this paper by an ecological input-output modeling based on the physical entry scheme. Included emissions and resources belong to six categories as: (1) greenhouse gas (GHG) in terms of CO 2, CH 4, and N 2O; (2) energy in terms of coal, crude oil, natural gas, hydropower, nuclear power, and firewood; (3) water in terms of freshwater; (4) exergy in terms of coal, crude oil, natural gas, grain, bean, tuber, cotton, peanut, rapeseed, sesame, jute, sugarcane, sugar beet, tobacco, silkworm feed, tea, fruits, vegetables, wood, bamboo, pulp, meat, egg, milk, wool, aquatic products, iron ore, copper ore, bauxite, lead ore, zinc ore, pyrite, phosphorite, gypsum, cement, nuclear fuel, and hydropower; (5) and (6) solar and cosmic emergies in terms of sunlight, wind power, deep earth heat, chemical power of rain, geopotential power of rain, chemical power of stream, geopotential power of stream, wave power, geothermal power, tide power, topsoil loss, coal, crude oil, natural gas, ferrous metal ore, non-ferrous metal ore, non-metal ore, cement, and nuclear fuel. Accounted based on the embodied intensities are carbon emissions and resources use embodied in the final use as rural consumption, urban consumption, government consumption, gross fixed capital formation, change in inventories, and export, as well as in the international trade balance. The resulted database is basic to environmental account of carbon emissions and resources use at various levels.

Weld geometry strength effect in 2219-T87 aluminum

NASA Technical Reports Server (NTRS)

Nunes, A. C., Jr.; Novak, H. L.; Mcilwain, M. C.

1981-01-01

A theory of the effect of geometry on the mechanical properties of a butt weld joint is worked out based upon the soft interlayer weld model. Tensile tests of 45 TIG butt welds and 6 EB beads-on-plate in 1/4-in. 2219-T87 aluminum plate made under a wide range of heat sink and power input conditions are analyzed using this theory. The analysis indicates that purely geometrical effects dominate in determining variations in weld joint strength with heat sink and power input. Variations in weld dimensions with cooling rate are significant as well as with power input. Weld size is suggested as a better indicator of the condition of a weld joint than energy input.

Impact of input data uncertainty on environmental exposure assessment models: A case study for electromagnetic field modelling from mobile phone base stations.

PubMed

Beekhuizen, Johan; Heuvelink, Gerard B M; Huss, Anke; Bürgi, Alfred; Kromhout, Hans; Vermeulen, Roel

2014-11-01

With the increased availability of spatial data and computing power, spatial prediction approaches have become a standard tool for exposure assessment in environmental epidemiology. However, such models are largely dependent on accurate input data. Uncertainties in the input data can therefore have a large effect on model predictions, but are rarely quantified. With Monte Carlo simulation we assessed the effect of input uncertainty on the prediction of radio-frequency electromagnetic fields (RF-EMF) from mobile phone base stations at 252 receptor sites in Amsterdam, The Netherlands. The impact on ranking and classification was determined by computing the Spearman correlations and weighted Cohen's Kappas (based on tertiles of the RF-EMF exposure distribution) between modelled values and RF-EMF measurements performed at the receptor sites. The uncertainty in modelled RF-EMF levels was large with a median coefficient of variation of 1.5. Uncertainty in receptor site height, building damping and building height contributed most to model output uncertainty. For exposure ranking and classification, the heights of buildings and receptor sites were the most important sources of uncertainty, followed by building damping, antenna- and site location. Uncertainty in antenna power, tilt, height and direction had a smaller impact on model performance. We quantified the effect of input data uncertainty on the prediction accuracy of an RF-EMF environmental exposure model, thereby identifying the most important sources of uncertainty and estimating the total uncertainty stemming from potential errors in the input data. This approach can be used to optimize the model and better interpret model output. Copyright © 2014 Elsevier Inc. All rights reserved.

Emissions-critical charge cooling using an organic rankine cycle

DOEpatents

Ernst, Timothy C.; Nelson, Christopher R.

2014-07-15

The disclosure provides a system including a Rankine power cycle cooling subsystem providing emissions-critical charge cooling of an input charge flow. The system includes a boiler fluidly coupled to the input charge flow, an energy conversion device fluidly coupled to the boiler, a condenser fluidly coupled to the energy conversion device, a pump fluidly coupled to the condenser and the boiler, an adjuster that adjusts at least one parameter of the Rankine power cycle subsystem to change a temperature of the input charge exiting the boiler, and a sensor adapted to sense a temperature characteristic of the vaporized input charge. The system includes a controller that can determine a target temperature of the input charge sufficient to meet or exceed predetermined target emissions and cause the adjuster to adjust at least one parameter of the Rankine power cycle to achieve the predetermined target emissions.

CMOS single-stage input-powered bridge rectifier with boost switch and duty cycle control

NASA Astrophysics Data System (ADS)

Radzuan, Roskhatijah; Mohd Salleh, Mohd Khairul; Hamzah, Mustafar Kamal; Ab Wahab, Norfishah

2017-06-01

This paper presents a single-stage input-powered bridge rectifier with boost switch for wireless-powered devices such as biomedical implants and wireless sensor nodes. Realised using CMOS process technology, it employs a duty cycle switch control to achieve high output voltage using boost technique, leading to a high output power conversion. It has only six external connections with the boost inductance. The input frequency of the bridge rectifier is set at 50 Hz, while the switching frequency is 100 kHz. The proposed circuit is fabricated on a single 0.18-micron CMOS die with a space area of 0.024 mm2. The simulated and measured results show good agreement.

Powered ankle-foot prosthesis to assist level-ground and stair-descent gaits.

PubMed

Au, Samuel; Berniker, Max; Herr, Hugh

2008-05-01

The human ankle varies impedance and delivers net positive work during the stance period of walking. In contrast, commercially available ankle-foot prostheses are passive during stance, causing many clinical problems for transtibial amputees, including non-symmetric gait patterns, higher gait metabolism, and poorer shock absorption. In this investigation, we develop and evaluate a myoelectric-driven, finite state controller for a powered ankle-foot prosthesis that modulates both impedance and power output during stance. The system employs both sensory inputs measured local to the external prosthesis, and myoelectric inputs measured from residual limb muscles. Using local prosthetic sensing, we first develop two finite state controllers to produce biomimetic movement patterns for level-ground and stair-descent gaits. We then employ myoelectric signals as control commands to manage the transition between these finite state controllers. To transition from level-ground to stairs, the amputee flexes the gastrocnemius muscle, triggering the prosthetic ankle to plantar flex at terminal swing, and initiating the stair-descent state machine algorithm. To transition back to level-ground walking, the amputee flexes the tibialis anterior muscle, triggering the ankle to remain dorsiflexed at terminal swing, and initiating the level-ground state machine algorithm. As a preliminary evaluation of clinical efficacy, we test the device on a transtibial amputee with both the proposed controller and a conventional passive-elastic control. We find that the amputee can robustly transition between the finite state controllers through direct muscle activation, allowing rapid transitioning from level-ground to stair walking patterns. Additionally, we find that the proposed finite state controllers result in a more biomimetic ankle response, producing net propulsive work during level-ground walking and greater shock absorption during stair descent. The results of this study highlight the potential of prosthetic leg controllers that exploit neural signals to trigger terrain-appropriate, local prosthetic leg behaviors.

Development of Solar Powered Irrigation System

NASA Astrophysics Data System (ADS)

Abdelkerim, A. I.; Sami Eusuf, M. M. R.; Salami, M. J. E.; Aibinu, A.; Eusuf, M. A.

2013-12-01

Development of a solar powered irrigation system has been discussed in this paper. This system would be SCADA-based and quite useful in areas where there is plenty of sunshine but insufficient water to carry out farming activities, such as rubber plantation, strawberry plantation, or any plantation, that requires frequent watering. The system is powered by solar system as a renewable energy which uses solar panel module to convert Sunlight into electricity. The development and implementation of an automated SCADA controlled system that uses PLC as a controller is significant to agricultural, oil and gas monitoring and control purpose purposes. In addition, the system is powered by an intelligent solar system in which solar panel targets the radiation from the Sun. Other than that, the solar system has reduced energy cost as well as pollution. The system is equipped with four input sensors; two soil moisture sensors, two level detection sensors. Soil moisture sensor measures the humidity of the soil, whereas the level detection sensors detect the level of water in the tank. The output sides consist of two solenoid valves, which are controlled respectively by two moistures sensors.

Design of ultra-low power biopotential amplifiers for biosignal acquisition applications.

PubMed

Zhang, Fan; Holleman, Jeremy; Otis, Brian P

2012-08-01

Rapid development in miniature implantable electronics are expediting advances in neuroscience by allowing observation and control of neural activities. The first stage of an implantable biosignal recording system, a low-noise biopotential amplifier (BPA), is critical to the overall power and noise performance of the system. In order to integrate a large number of front-end amplifiers in multichannel implantable systems, the power consumption of each amplifier must be minimized. This paper introduces a closed-loop complementary-input amplifier, which has a bandwidth of 0.05 Hz to 10.5 kHz, an input-referred noise of 2.2 μ Vrms, and a power dissipation of 12 μW. As a point of comparison, a standard telescopic-cascode closed-loop amplifier with a 0.4 Hz to 8.5 kHz bandwidth, input-referred noise of 3.2 μ Vrms, and power dissipation of 12.5 μW is presented. Also for comparison, we show results from an open-loop complementary-input amplifier that exhibits an input-referred noise of 3.6 μ Vrms while consuming 800 nW of power. The two closed-loop amplifiers are fabricated in a 0.13 μ m CMOS process. The open-loop amplifier is fabricated in a 0.5 μm SOI-BiCMOS process. All three amplifiers operate with a 1 V supply.

Hybrid life-cycle assessment (LCA) of CO2 emission with management alternatives for household food wastes in Japan.

PubMed

Inaba, Rokuta; Nansai, Keisuke; Fujii, Minoru; Hashimoto, Seiji

2010-06-01

In this study, we conducted a hybrid life-cycle assessment (LCA) to evaluate reductions in CO(2) emissions by food waste biogasification of household food wastes in Japan. Two alternative scenarios were examined. In one alternative (Ref), all combustible municipal solid wastes (MSWs), including food waste, are incinerated. In the other (Bio), food waste is biogasified, while the other combustible wastes are incinerated. An inventory analysis of energy and material flow in the MSW management system was conducted. Subsequently, the inventory data were summarized into an input-output format, and a make-use input-output framework was applied. Furthermore, a production equilibrium model was established using a matrix representing the input- output relationship of energy and materials among the processes and sectors. Several levels of power generation efficiency from incineration were applied as a sensitivity analysis. The hybrid LCA indicated that the difference between the Bio and Ref scenarios, from the perspective of CO( 2) emissions, is relatively small. However, a 13-14% reduction of CO(2) emissions of the total waste management sector in Japan may be achieved by improving the efficiency of power generation from incineration from 10% to 25%.

Noise propagation effects in power supply distribution systems for high-energy physics experiments

NASA Astrophysics Data System (ADS)

Arteche, F.; Rivetta, C.; Iglesias, M.; Echeverria, I.; Pradas, A.; Arcega, F. J.

2017-12-01

High-energy physics experiments are supplied by thousands of power supply units placed in distant areas from the front-end electronics. The power supply units and the front-end electronics are connected through long power cables that propagate the output noise from the power supplies to the detector. This paper addresses the effect of long cables on the noise propagation and the impact that those cables have on the conducted emission levels required for the power supplies and the selection of EMI filters for the front-end electronic low-voltage input. This analysis is part of the electromagnetic compatibility based design focused on functional safety to define the type of cable, shield connections, EMI filters and power supply specifications required to ensure the successful integration of the detector and, specifically, to achieve the designed performance of the front-end electronics.

Noise propagation effects in power supply distribution systems for high-energy physics experiments

DOE PAGES

Arteche, F.; Rivetta, C.; Iglesias, M.; ...

2017-12-05

High-energy physics experiments are supplied by thousands of power supply units placed in distant areas from the front-end electronics. The power supply units and the front-end electronics are connected through long power cables that propagate the output noise from the power supplies to the detector. Here, this paper addresses the effect of long cables on the noise propagation and the impact that those cables have on the conducted emission levels required for the power supplies and the selection of EMI filters for the front-end electronic low-voltage input. Lastly, this analysis is part of the electromagnetic compatibility based design focused onmore » functional safety to define the type of cable, shield connections, EMI filters and power supply specifications required to ensure the successful integration of the detector and, specifically, to achieve the designed performance of the front-end electronics.« less

Noise propagation effects in power supply distribution systems for high-energy physics experiments

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

Arteche, F.; Rivetta, C.; Iglesias, M.

High-energy physics experiments are supplied by thousands of power supply units placed in distant areas from the front-end electronics. The power supply units and the front-end electronics are connected through long power cables that propagate the output noise from the power supplies to the detector. Here, this paper addresses the effect of long cables on the noise propagation and the impact that those cables have on the conducted emission levels required for the power supplies and the selection of EMI filters for the front-end electronic low-voltage input. Lastly, this analysis is part of the electromagnetic compatibility based design focused onmore » functional safety to define the type of cable, shield connections, EMI filters and power supply specifications required to ensure the successful integration of the detector and, specifically, to achieve the designed performance of the front-end electronics.« less

Vibration Power Flow In A Constrained Layer Damping Cylindrical Shell

NASA Astrophysics Data System (ADS)

Wang, Yun; Zheng, Gangtie

2012-07-01

In this paper, the vibration power flow in a constrained layer damping (CLD) cylindrical shell using wave propagation approach is investigated. The dynamic equations of the shell are derived with the Hamilton principle in conjunction with the Donnell shell assumption. With these equations, the dynamic responses of the system under a line circumferential cosine harmonic exciting force is obtained by employing the Fourier transform and the residue theorem. The vibration power flows inputted to the system and transmitted along the shell axial direction are both studied. The results show that input power flow varies with driving frequency and circumferential mode order, and the constrained damping layer can obviously restrict the exciting force from inputting power flow into the base shell especially for a thicker viscoelastic layer, a thicker or stiffer constraining layer (CL), and a higher circumferential mode order, can rapidly attenuate the vibration power flow transmitted along the base shell axial direction.

Identification of single-input-single-output quantum linear systems

NASA Astrophysics Data System (ADS)

Levitt, Matthew; GuÅ£ǎ, Mǎdǎlin

2017-03-01

The purpose of this paper is to investigate system identification for single-input-single-output general (active or passive) quantum linear systems. For a given input we address the following questions: (1) Which parameters can be identified by measuring the output? (2) How can we construct a system realization from sufficient input-output data? We show that for time-dependent inputs, the systems which cannot be distinguished are related by symplectic transformations acting on the space of system modes. This complements a previous result of Guţă and Yamamoto [IEEE Trans. Autom. Control 61, 921 (2016), 10.1109/TAC.2015.2448491] for passive linear systems. In the regime of stationary quantum noise input, the output is completely determined by the power spectrum. We define the notion of global minimality for a given power spectrum, and characterize globally minimal systems as those with a fully mixed stationary state. We show that in the case of systems with a cascade realization, the power spectrum completely fixes the transfer function, so the system can be identified up to a symplectic transformation. We give a method for constructing a globally minimal subsystem direct from the power spectrum. Restricting to passive systems the analysis simplifies so that identifiability may be completely understood from the eigenvalues of a particular system matrix.

Series-Connected Buck Boost Regulators

NASA Technical Reports Server (NTRS)

Birchenough, Arthur G.

2005-01-01

A series-connected buck boost regulator (SCBBR) is an electronic circuit that bucks a power-supply voltage to a lower regulated value or boosts it to a higher regulated value. The concept of the SCBBR is a generalization of the concept of the SCBR, which was reported in "Series-Connected Boost Regulators" (LEW-15918), NASA Tech Briefs, Vol. 23, No. 7 (July 1997), page 42. Relative to prior DC-voltage-regulator concepts, the SCBBR concept can yield significant reductions in weight and increases in power-conversion efficiency in many applications in which input/output voltage ratios are relatively small and isolation is not required, as solar-array regulation or battery charging with DC-bus regulation. Usually, a DC voltage regulator is designed to include a DC-to-DC converter to reduce its power loss, size, and weight. Advances in components, increases in operating frequencies, and improved circuit topologies have led to continual increases in efficiency and/or decreases in the sizes and weights of DC voltage regulators. The primary source of inefficiency in the DC-to-DC converter portion of a voltage regulator is the conduction loss and, especially at high frequencies, the switching loss. Although improved components and topology can reduce the switching loss, the reduction is limited by the fact that the converter generally switches all the power being regulated. Like the SCBR concept, the SCBBR concept involves a circuit configuration in which only a fraction of the power is switched, so that the switching loss is reduced by an amount that is largely independent of the specific components and circuit topology used. In an SCBBR, the amount of power switched by the DC-to-DC converter is only the amount needed to make up the difference between the input and output bus voltage. The remaining majority of the power passes through the converter without being switched. The weight and power loss of a DC-to-DC converter are determined primarily by the amount of power processed. In the SCBBR, the unswitched majority of the power is passed through with very little power loss, and little if any increase in the sizes of the converter components is needed to enable the components to handle the unswitched power. As a result, the power-conversion efficiency of the regulator can be very high, as shown in the example of Figure 1. A basic SCBBR includes a DC-to-DC converter (see Figure 2). The switches and primary winding of a transformer in the converter is connected across the input bus, while the secondary winding and switches are connected in series with the output bus, so that the output voltage is the sum of the input voltage and the secondary voltage of the converter. In the breadboard SCBBR, the input voltage applied to the primary winding is switched by use of metal oxide/semiconductor field-effect transistors (MOSFETs) in a full bridge circuit; the secondary winding is center-tapped, with two MOSFET switches and diode rectifiers connected in opposed series in each leg. The sets of opposed switches and rectifiers are what enable operation in either a boost or a buck mode. In the boost mode, input voltage and current, and the output voltage and current are all positive; that is, the secondary voltage is added to the input voltage and the net output voltage can be regulated at a value equal or greater than the input voltage. In the buck mode, input voltage is still positive and the current still flows in the same direction in the secondary, but the switches are controlled such that some power flows from the secondary to the primary. The voltage across the secondary and the current into the primary are reversed. The result is that the output voltage is lower than the input voltage, and some power is recirculated from the converter secondary back to the input. Quantitatively, the advantage of an SCBBR is a direct function of the regulation range required. If, for example, a regulation range of 20 percent is required for a 500-W supply, th it suffices to design the DC-to-DC converter in the SCBBR for a power rating of only 100 W. The switching loss and size are much smaller than those of a conventional regulator that must be rated for switching of all 500 W. The reduction in size and the increase in efficiency are not directly proportional to switched-power ratio of 5:1 because the additional switches contribute some conduction loss and the input and output filters must be larger than those typically required for a 100-W converter. Nevertheless, the power loss and the size can be much smaller than those of a 500-W converter.

Voltage balanced multilevel voltage source converter system

DOEpatents

Peng, Fang Zheng; Lai, Jih-Sheng

1997-01-01

A voltage balanced multilevel converter for high power AC applications such as adjustable speed motor drives and back-to-back DC intertie of adjacent power systems. This converter provides a multilevel rectifier, a multilevel inverter, and a DC link between the rectifier and the inverter allowing voltage balancing between each of the voltage levels within the multilevel converter. The rectifier is equipped with at least one phase leg and a source input node for each of the phases. The rectifier is further equipped with a plurality of rectifier DC output nodes. The inverter is equipped with at least one phase leg and a load output node for each of the phases. The inverter is further equipped with a plurality of inverter DC input nodes. The DC link is equipped with a plurality of rectifier charging means and a plurality of inverter discharging means. The plurality of rectifier charging means are connected in series with one of the rectifier charging means disposed between and connected in an operable relationship with each adjacent pair of rectifier DC output nodes. The plurality of inverter discharging means are connected in series with one of the inverter discharging means disposed between and connected in an operable relationship with each adjacent pair of inverter DC input nodes. Each of said rectifier DC output nodes are individually electrically connected to the respective inverter DC input nodes. By this means, each of the rectifier DC output nodes and each of the inverter DC input nodes are voltage balanced by the respective charging and discharging of the rectifier charging means and the inverter discharging means.

Voltage balanced multilevel voltage source converter system

DOEpatents

Peng, F.Z.; Lai, J.S.

1997-07-01

Disclosed is a voltage balanced multilevel converter for high power AC applications such as adjustable speed motor drives and back-to-back DC intertie of adjacent power systems. This converter provides a multilevel rectifier, a multilevel inverter, and a DC link between the rectifier and the inverter allowing voltage balancing between each of the voltage levels within the multilevel converter. The rectifier is equipped with at least one phase leg and a source input node for each of the phases. The rectifier is further equipped with a plurality of rectifier DC output nodes. The inverter is equipped with at least one phase leg and a load output node for each of the phases. The inverter is further equipped with a plurality of inverter DC input nodes. The DC link is equipped with a plurality of rectifier charging means and a plurality of inverter discharging means. The plurality of rectifier charging means are connected in series with one of the rectifier charging means disposed between and connected in an operable relationship with each adjacent pair of rectifier DC output nodes. The plurality of inverter discharging means are connected in series with one of the inverter discharging means disposed between and connected in an operable relationship with each adjacent pair of inverter DC input nodes. Each of said rectifier DC output nodes are individually electrically connected to the respective inverter DC input nodes. By this means, each of the rectifier DC output nodes and each of the inverter DC input nodes are voltage balanced by the respective charging and discharging of the rectifier charging means and the inverter discharging means. 15 figs.

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.

The behavior of gain and saturation characteristics versus temperature in a copper bromide laser

NASA Astrophysics Data System (ADS)

Mohammadpour Lima, S.; Behrouzinia, S.; Salem, M. K.; Elahei, M.; Khorasani, K.; Dorranian, D.

2017-05-01

A pair of copper bromide lasers in an oscillator-amplifier configuration was used to investigate the temperature dependence of the small-signal gain, saturation intensity, and output power of the laser. The observations were explained in terms of the electron temperature and energy levels of transition. An optimum electrical input power of 1.6 kW and a corresponding operational temperature of 510 °C were determined for the maximum values of these parameters. The balance between the microscopic parameters, such as stimulated emission cross-section, laser upper-level lifetime, and population inversion, which determine the behavior of the amplifying parameters and laser output power with respect to the operational temperature, has been investigated. We used the steady-state rate equation from the Hargrove model to determine the amplifying parameters, instead of the Frantz-Nodvik formula. The power extracted from the amplifier exceeds that achieved with the same device as the oscillator by more than 60%.

Input-current shaped ac to dc converters

NASA Technical Reports Server (NTRS)

1986-01-01

The problem of achieving near unity power factor while supplying power to a dc load from a single phase ac source of power is examined. Power processors for this application must perform three functions: input current shaping, energy storage, and output voltage regulation. The methods available for performing each of these three functions are reviewed. Input current shaping methods are either active or passive, with the active methods divided into buck-like and boost-like techniques. In addition to large reactances, energy storage methods include resonant filters, active filters, and active storage schemes. Fast voltage regulation can be achieved by post regulation or by supplementing the current shaping topology with an extra switch. Some indications of which methods are best suited for particular applications concludes the discussion.

Method and system for conserving power in a telecommunications network during emergency situations

DOEpatents

Conrad, Stephen H [Algodones, NM; O'Reilly, Gerard P [Manalapan, NJ

2011-10-11

Disclosed is a method and apparatus for conserving power in a telecommunications network during emergency situations. A permissible number list of emergency and/or priority numbers is stored in the telecommunications network. In the event of an emergency or power failure, input digits of a call to the telecommunications network are compared to the permissible number list. The call is processed in the telecommunications network and routed to its destination if the input digits match an entry in the permissible number list. The call is dropped without any further processing if the input digits do not match an entry in the permissible number list. Thus, power can be conserved in emergency situations by only allowing emergency and/or priority calls.

Development of size reduction equations for calculating power input for grinding pine wood chips using hammer mill

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

Naimi, Ladan J.; Collard, Flavien; Bi, Xiaotao

Size reduction is an unavoidable operation for preparing biomass for biofuels and bioproduct conversion. Yet, there is considerable uncertainty in power input requirement and the uniformity of ground biomass. Considerable gains are possible if the required power input for a size reduction ratio is estimated accurately. In this research three well-known mechanistic equations attributed to Rittinger, Kick, and Bond available for predicting energy input for grinding pine wood chips were tested against experimental grinding data. Prior to testing, samples of pine wood chips were conditioned to 11.7% wb, moisture content. The wood chips were successively ground in a hammer millmore » using screen sizes of 25.4 mm, 10 mm, 6.4 mm, and 3.2 mm. The input power and the flow of material into the grinder were recorded continuously. The recorded power input vs. mean particle size showed that the Rittinger equation had the best fit to the experimental data. The ground particle sizes were 4 to 7 times smaller than the size of installed screen. Geometric mean size of particles were calculated using two methods (1) Tyler sieves and using particle size analysis and (2) Sauter mean diameter calculated from the ratio of volume to surface that were estimated from measured length and width. The two mean diameters agreed well, pointing to the fact that either mechanical sieving or particle imaging can be used to characterize particle size. In conclusion, specific energy input to the hammer mill increased from 1.4 kWh t –1 (5.2 J g –1) for large 25.1-mm screen to 25 kWh t –1 (90.4 J g –1) for small 3.2-mm screen.« less

Development of size reduction equations for calculating power input for grinding pine wood chips using hammer mill

DOE PAGES

Naimi, Ladan J.; Collard, Flavien; Bi, Xiaotao; ...

2016-01-05

Size reduction is an unavoidable operation for preparing biomass for biofuels and bioproduct conversion. Yet, there is considerable uncertainty in power input requirement and the uniformity of ground biomass. Considerable gains are possible if the required power input for a size reduction ratio is estimated accurately. In this research three well-known mechanistic equations attributed to Rittinger, Kick, and Bond available for predicting energy input for grinding pine wood chips were tested against experimental grinding data. Prior to testing, samples of pine wood chips were conditioned to 11.7% wb, moisture content. The wood chips were successively ground in a hammer millmore » using screen sizes of 25.4 mm, 10 mm, 6.4 mm, and 3.2 mm. The input power and the flow of material into the grinder were recorded continuously. The recorded power input vs. mean particle size showed that the Rittinger equation had the best fit to the experimental data. The ground particle sizes were 4 to 7 times smaller than the size of installed screen. Geometric mean size of particles were calculated using two methods (1) Tyler sieves and using particle size analysis and (2) Sauter mean diameter calculated from the ratio of volume to surface that were estimated from measured length and width. The two mean diameters agreed well, pointing to the fact that either mechanical sieving or particle imaging can be used to characterize particle size. In conclusion, specific energy input to the hammer mill increased from 1.4 kWh t –1 (5.2 J g –1) for large 25.1-mm screen to 25 kWh t –1 (90.4 J g –1) for small 3.2-mm screen.« less

High power density dc-to-dc converters for aerospace applications

NASA Technical Reports Server (NTRS)

Divan, Deepakraj M.

1990-01-01

Three dc-to-dc converter topologies aimed at high-power high-frequency applications are introduced. Major system parasitics, namely, the leakage inductance of the transformer and the device output capacitance are efficiently utilized. Of the three circuits, the single-phase and three-phase versions of the dual active bridge topology demonstrate minimal stresses, better utilization of the transformer, bidirectional, and buck-boost modes of operation. All circuits operate at a constant switching frequency, thus simplifying design of the reactive elements. The power transfer characteristics and soft-switching regions on the Vout-Iout plane are identified. Two coaxial transformers with different cross-sections were built for a rating of 50 kVA. Based on the single-phase dual active bridge topology, a 50 kW, 50 kHz converter operating at an input voltage of 200 Vdc and an output voltage of 1600 Vdc was fabricated. Characteristics of current-fed output make the dual active bridge topologies amenable to paralleling and hence extension to megawatt power levels. Projections to a 1 MW system operating from a 500 Vdc input, at an output voltage of 10 kVdc and a switching frequency of 50 kHz, using MOS-controlled thyristors, coaxially wound transformers operating at three times the present current density with cooling, and multilayer ceramic capacitors, suggests an overall power density of 0.075 to 0.08 kg/kW and an overall efficiency of 96 percent.

Scaling of Ion Thrusters to Low Power

NASA Technical Reports Server (NTRS)

Patterson, Michael J.; Grisnik, Stanley P.; Soulas, George C.

1998-01-01

Analyses were conducted to examine ion thruster scaling relationships in detail to determine performance limits, and lifetime expectations for thruster input power levels below 0.5 kW. This was motivated by mission analyses indicating the potential advantages of high performance, high specific impulse systems for small spacecraft. The design and development status of a 0.1-0.3 kW prototype small thruster and its components are discussed. Performance goals include thruster efficiencies on the order of 40% to 54% over a specific impulse range of 2000 to 3000 seconds, with a lifetime in excess of 8000 hours at full power. Thruster technologies required to achieve the performance and lifetime targets are identified.

Ion optics for high power 50-cm-diam ion thrusters

NASA Technical Reports Server (NTRS)

Rawlin, Vincent K.; Millis, Marc G.

1989-01-01

The process used at the NASA-Lewis to fabricate 30 and 50-cm-diameter ion optics is described. The ion extraction capabilities of the 30 and 50-cm diameter ion optics were evaluated on divergent field and ring-cusp discharge chambers and compared. Perveance was found to be sensitive to the effects of the type and power of the discharge chamber and to the accelerator electrode hole diameter. Levels of up to 0.64 N and 20 kW for thrust and input power, respectively, were demonstrated with the divergent-field discharge chamber. Thruster efficiencies and specific impulse values up to 79 percent and 5000 sec., respectively, were achieved with the ring-cusp discharge chamber.

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.

High-power, single-frequency, continuous-wave second-harmonic-generation of ytterbium fiber laser in PPKTP and MgO:sPPLT.

PubMed

Kumar, S Chaitanya; Samanta, G K; Ebrahim-Zadeh, M

2009-08-03

Characteristics of high-power, narrow-linewidth, continuous-wave (cw) green radiation obtained by simple single-pass second-harmonic-generation (SHG) of a cw ytterbium fiber laser at 1064 nm in the nonlinear crystals of PPKTP and MgO:sPPLT are studied and compared. Temperature tuning and SHG power scaling up to nearly 10 W for input fundamental power levels up to 30 W are performed. Various contributions to thermal effects in both crystals, limiting the SHG conversion efficiency, are studied. Optimal focusing conditions and thermal management schemes are investigated to maximize SHG performance in MgO:sPPLT. Stable green output power and high spatial beam quality with M(2)<1.33 and M(2)<1.34 is achieved in MgO:sPPLT and PPKTP, respectively.

JEDI: Jobs and Economic Development Impacts Model, National Renewable Energy Laboratory (NREL) (Fact Sheet)

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

Not Available

2009-12-01

The Jobs and Economic Development Impact (JEDI) models are user-friendly tools that estimate the economic impacts of constructing and operating power generation and biofuel plants at the local (usually state) level. First developed by NREL's Wind Powering America program to model wind energy jobs and impacts, JEDI has been expanded to biofuels, concentrating solar power, coal, and natural gas power plants. Based on project-specific and default inputs (derived from industry norms), JEDI estimates the number of jobs and economic impacts to a local area (usually a state) that could reasonably be supported by a power generation project. For example, JEDImore » estimates the number of in-state construction jobs from a new wind farm. This fact sheet provides an overview of the JEDI model as it pertains to wind energy projects.« less

System design of ELITE power processing unit

NASA Astrophysics Data System (ADS)

Caldwell, David J.

The Electric Propulsion Insertion Transfer Experiment (ELITE) is a space mission planned for the mid 1990s in which technological readiness will be demonstrated for electric orbit transfer vehicles (EOTVs). A system-level design of the power processing unit (PPU), which conditions solar array power for the arcjet thruster, was performed to optimize performance with respect to reliability, power output, efficiency, specific mass, and radiation hardness. The PPU system consists of multiphased parallel switchmode converters, configured as current sources, connected directly from the array to the thruster. The PPU control system includes a solar array peak power tracker (PPT) to maximize the power delivered to the thruster regardless of variations in array characteristics. A stability analysis has been performed to verify that the system is stable despite the nonlinear negative impedance of the PPU input and the arcjet thruster. Performance specifications are given to provide the required spacecraft capability with existing technology.

An Integrated Gate Driver in 4H-SiC for Power Converter Applications

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

Ericson, Milton Nance; Frank, Steven Shane; Britton, Charles

2014-01-01

A gate driver fabricated in a 2-um 4H silicon carbide (SiC) process is presented. This process was optimized for vertical power MOSFET fabrication but accommodated integration of a few low-voltage device types including N-channel MOSFETs, resistors, and capacitors. The gate driver topology employed incorporates an input level translator, variable power connections, and separate power supply connectivity allowing selection of the output signal drive amplitude. The output stage utilizes a source follower pull-up device that is both overdriven and body source connected to improve rise time behavior. Full characterization of this design driving a SiC power MOSFET is presented including risemore » and fall times, propagation delays, and power consumption. All parameters were measured to elevated temperatures exceeding 300 C. Details of the custom test system hardware and software utilized for gate driver testing are also provided.« less

Analysis of control system responses for aircraft stability and efficient numerical techniques for real-time simulations

NASA Astrophysics Data System (ADS)

Stroe, Gabriela; Andrei, Irina-Carmen; Frunzulica, Florin

2017-01-01

The objectives of this paper are the study and the implementation of both aerodynamic and propulsion models, as linear interpolations using look-up tables in a database. The aerodynamic and propulsion dependencies on state and control variable have been described by analytic polynomial models. Some simplifying hypotheses were made in the development of the nonlinear aircraft simulations. The choice of a certain technique to use depends on the desired accuracy of the solution and the computational effort to be expended. Each nonlinear simulation includes the full nonlinear dynamics of the bare airframe, with a scaled direct connection from pilot inputs to control surface deflections to provide adequate pilot control. The engine power dynamic response was modeled with an additional state equation as first order lag in the actual power level response to commanded power level was computed as a function of throttle position. The number of control inputs and engine power states varied depending on the number of control surfaces and aircraft engines. The set of coupled, nonlinear, first-order ordinary differential equations that comprise the simulation model can be represented by the vector differential equation. A linear time-invariant (LTI) system representing aircraft dynamics for small perturbations about a reference trim condition is given by the state and output equations present. The gradients are obtained numerically by perturbing each state and control input independently and recording the changes in the trimmed state and output equations. This is done using the numerical technique of central finite differences, including the perturbations of the state and control variables. For a reference trim condition of straight and level flight, linearization results in two decoupled sets of linear, constant-coefficient differential equations for longitudinal and lateral / directional motion. The linearization is valid for small perturbations about the reference trim condition. Experimental aerodynamic and thrust data are used to model the applied aerodynamic and propulsion forces and moments for arbitrary states and controls. There is no closed form solution to such problems, so the equations must be solved using numerical integration. Techniques for solving this initial value problem for ordinary differential equations are employed to obtain approximate solutions at discrete points along the aircraft state trajectory.

Experimental study of an X-band phase-locked relativistic backward wave oscillator

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

Wu, Y.; Science and Technology on High Power Microwave Laboratory, Mianyang 621900; Li, Z. H.

2015-11-15

To achieve high power microwave combined with high frequency band, an X-band phase-locked relativistic backward wave oscillator (RBWO) is proposed and investigated theoretically and experimentally using a modulated electron beam. In the device, an overmoded input cavity and a buncher cavity are employed to premodulate the electron beam. Particle-in-cell simulation shows that an input power of 90 kW is sufficient to lock the frequency and phase of 1.5 GW output microwave with the locking bandwidth of 60 MHz. Moreover, phase and frequency locking of an RBWO has been accomplished experimentally with an output power of 1.5 GW. The fluctuation of the relative phase differencemore » between output microwave and input RF signal is less than ±20° with the locking duration of about 50 ns. The input RF power required to lock the oscillator is only 90 kW.« less

Single-stage three-phase boost power factor correction circuit for AC-DC converter

NASA Astrophysics Data System (ADS)

Azazi, Haitham Z.; Ahmed, Sayed M.; Lashine, Azza E.

2018-01-01

This article presents a single-stage three-phase power factor correction (PFC) circuit for AC-to-DC converter using a single-switch boost regulator, leading to improve the input power factor (PF), reducing the input current harmonics and decreasing the number of required active switches. A novel PFC control strategy which is characterised as a simple and low-cost control circuit was adopted, for achieving a good dynamic performance, unity input PF, and minimising the harmonic contents of the input current, at which it can be applied to low/medium power converters. A detailed analytical, simulation and experimental studies were therefore conducted. The effectiveness of the proposed controller algorithm is validated by the simulation results, which were carried out using MATLAB/SIMULINK environment. The proposed system is built and tested in the laboratory using DSP-DS1104 digital control board for an inductive load. The results revealed that the total harmonic distortion in the supply current was very low. Finally, a good agreement between simulation and experimental results was achieved.

Modelling of fluid flow phenomenon in laser+GMAW hybrid welding of aluminum alloy considering three phase coupling and arc plasma shear stress

NASA Astrophysics Data System (ADS)

Xu, Guoxiang; Li, Pengfei; Cao, Qingnan; Hu, Qingxian; Gu, Xiaoyan; Du, Baoshuai

2018-03-01

The present study aims to develop a unified three dimensional numerical model for fiber laser+GMAW hybrid welding, which is used to study the fluid flow phenomena in hybrid welding of aluminum alloy and the influence of laser power on weld pool dynamic behavior. This model takes into account the coupling of gas, liquid and metal phases. Laser heat input is described using a cone heat source model with changing peak power density, its height being determined based on the keyhole size. Arc heat input is modeled as a double ellipsoid heat source. The arc plasma flow and droplet transfer are simulated through the two simplified models. The temperature and velocity fields for different laser powers are calculated. The computed results are in general agreement with the experimental data. Both the peak and average values of fluid flow velocity during hybrid welding are much higher than those of GMAW. At a low level of laser power, both the arc force and droplet impingement force play a relatively large role on fluid flow in the hybrid welding. Keyhole depth always oscillates within a range. With an increase in laser power, the weld pool behavior becomes more complex. An anti-clockwise vortex is generated and the stability of keyhole depth is improved. Besides, the effects of laser power on different driving forces of fluid flow in weld pool are also discussed.

The SPS interference problem-electronic system effects and mitigation techniques

NASA Technical Reports Server (NTRS)

Juroshek, J. R.

1980-01-01

The potential for interference between solar power satellites (SPS) and other Earth satellite operations was examined along with interference problems involving specific electronic devices. Conclusions indicate that interference is likely in the 2500 MHz to 2690 MHz direct broadcast satellite band adjacent to SPS. Estimates of the adjacent channel noise from SPS in this band are as high as -124 dBc/4 kHz and -100 dBc/MHz, where dBc represents decibels relative to the total power in the fundamental. A second potential problem is the 7350 MHz, 3d harmonic from SPS that falls within the 7300 MHz to 7450 MHz space to Earth, government, satellite assignment. Catastrophic failures can be produced in integrated circuits when the microwave power levels coupled into inputs and power leads reach 1 to 100 watts. The failures are typically due to bonding wire melting, metallization failures, and junction shorting. Nondestructive interaction or interference, however, generally occurs with coupled power levels of the order of 10 milliwatts. This integration is due to the rectification of microwave energy by the numerous pn junctions within these circuits.

Human responses to upright tilt: a window on central autonomic integration

NASA Technical Reports Server (NTRS)

Cooke, W. H.; Hoag, J. B.; Crossman, A. A.; Kuusela, T. A.; Tahvanainen, K. U.; Eckberg, D. L.

1999-01-01

1. We examined interactions between haemodynamic and autonomic neural oscillations during passive upright tilt, to gain better insight into human autonomic regulatory mechanisms. 2. We recorded the electrocardiogram, finger photoplethysmographic arterial pressure, respiration and peroneal nerve muscle sympathetic activity in nine healthy young adults. Subjects breathed in time with a metronome at 12 breaths min-1 (0.2 Hz) for 5 min each, in supine, and 20, 40, 60, 70 and 80 deg head-up positions. We performed fast Fourier transform (and autoregressive) power spectral analyses and integrated low-frequency (0.05-0.15 Hz) and respiratory-frequency (0. 15-0.5 Hz) spectral powers. 3. Integrated areas of muscle sympathetic bursts and their low- and respiratory-frequency spectral powers increased directly and significantly with the tilt angle. The centre frequency of low-frequency sympathetic oscillations was constant before and during tilt. Sympathetic bursts occurred more commonly during expiration than inspiration at low tilt angles, but occurred equally in expiration and inspiration at high tilt angles. 4. Systolic and diastolic pressures and their low- and respiratory-frequency spectral powers increased, and R-R intervals and their respiratory-frequency spectral power decreased progressively with the tilt angle. Low-frequency R-R interval spectral power did not change. 5. The cross-spectral phase angle between systolic pressures and R-R intervals remained constant and consistently negative at the low frequency, but shifted progressively from positive to negative at the respiratory frequency during tilt. The arterial baroreflex modulus, calculated from low-frequency cross-spectra, decreased at high tilt angles. 6. Our results document changes of baroreflex responses during upright tilt, which may reflect leftward movement of subjects on their arterial pressure sympathetic and vagal response relations. The intensity, but not the centre frequency of low-frequency cardiovascular rhythms, is modulated by the level of arterial baroreceptor input. Tilt reduces respiratory gating of sympathetic and vagal motoneurone responsiveness to stimulatory inputs for different reasons; during tilt, sympathetic stimulation increases to a level that overwhelms the respiratory gate, and vagal stimulation decreases to a level below that necessary for maximal respiratory gating to occur.

Human responses to upright tilt: a window on central autonomic integration.

PubMed

Cooke, W H; Hoag, J B; Crossman, A A; Kuusela, T A; Tahvanainen, K U; Eckberg, D L

1999-06-01

1. We examined interactions between haemodynamic and autonomic neural oscillations during passive upright tilt, to gain better insight into human autonomic regulatory mechanisms. 2. We recorded the electrocardiogram, finger photoplethysmographic arterial pressure, respiration and peroneal nerve muscle sympathetic activity in nine healthy young adults. Subjects breathed in time with a metronome at 12 breaths min-1 (0.2 Hz) for 5 min each, in supine, and 20, 40, 60, 70 and 80 deg head-up positions. We performed fast Fourier transform (and autoregressive) power spectral analyses and integrated low-frequency (0.05-0.15 Hz) and respiratory-frequency (0. 15-0.5 Hz) spectral powers. 3. Integrated areas of muscle sympathetic bursts and their low- and respiratory-frequency spectral powers increased directly and significantly with the tilt angle. The centre frequency of low-frequency sympathetic oscillations was constant before and during tilt. Sympathetic bursts occurred more commonly during expiration than inspiration at low tilt angles, but occurred equally in expiration and inspiration at high tilt angles. 4. Systolic and diastolic pressures and their low- and respiratory-frequency spectral powers increased, and R-R intervals and their respiratory-frequency spectral power decreased progressively with the tilt angle. Low-frequency R-R interval spectral power did not change. 5. The cross-spectral phase angle between systolic pressures and R-R intervals remained constant and consistently negative at the low frequency, but shifted progressively from positive to negative at the respiratory frequency during tilt. The arterial baroreflex modulus, calculated from low-frequency cross-spectra, decreased at high tilt angles. 6. Our results document changes of baroreflex responses during upright tilt, which may reflect leftward movement of subjects on their arterial pressure sympathetic and vagal response relations. The intensity, but not the centre frequency of low-frequency cardiovascular rhythms, is modulated by the level of arterial baroreceptor input. Tilt reduces respiratory gating of sympathetic and vagal motoneurone responsiveness to stimulatory inputs for different reasons; during tilt, sympathetic stimulation increases to a level that overwhelms the respiratory gate, and vagal stimulation decreases to a level below that necessary for maximal respiratory gating to occur.

Plasma core power exhaust in ELMy H-Mode in JET with ITER-Like Wall

NASA Astrophysics Data System (ADS)

Guillemaut, C.; Metzger, C.; Appel, L.; Drewelow, P.; Horvath, L.; Matthews, G. F.; Szepesi, G.; Solano, E. R.; contributors, JET

2018-07-01

The mitigation of target heat load in future steady state fusion devices will require dissipation of a significant amount of power through radiation. Plasma operations relying on ELMy H-modes could be problematic since ELMs may transport substantial amounts of power to the target without significant dissipation. Therefore, estimation of the average ELM power exhaust from the plasma core is crucial to evaluate the potential limitation on the power dissipation in ELMy H-mode regime. A series of more than 50 Type-I ELMy H-mode discharges in JET with ITER-Like Wall (JET-ILW) with a wide range of conditions has been used here to compare the average ELM power to the average input power. The effect of input power, ELM frequency, plasma current, confinement and radiation on ELM power exhaust has been studied and reported in this paper. Good agreement has been found here with previous studies made in carbon machines. This work suggests that it should not be possible to dissipate more than 70%–80% of the input power in Type-I ELMy H-modes in JET-ILW which is consistent with the maximum radiative fraction found experimentally.

Optical power splitter for splitting high power light

DOEpatents

English, Jr., Ronald E.; Christensen, John J.

1995-01-01

An optical power splitter for the distribution of high-power light energy has a plurality of prisms arranged about a central axis to form a central channel. The input faces of the prisms are in a common plane which is substantially perpendicular to the central axis. A beam of light which is substantially coaxial to the central axis is incident on the prisms and at least partially strikes a surface area of each prism input face. The incident beam also partially passes through the central channel.

Piezoelectric transformer and modular connections for high power and high voltage power supplies

NASA Technical Reports Server (NTRS)

Vazquez Carazo, Alfredo (Inventor)

2006-01-01

A modular design for combining piezoelectric transformers is provided for high voltage and high power conversion applications. The input portions of individual piezoelectric transformers are driven for a single power supply. This created the vibration and the conversion of electrical to electrical energy from the input to the output of the transformers. The output portions of the single piezoelectric transformers are combining in series and/or parallel to provide multiple outputs having different rating of voltage and current.

Second harmonic generation in gallium phosphide photonic crystal nanocavities with ultralow continuous wave pump power.

PubMed

Rivoire, Kelley; Lin, Ziliang; Hatami, Fariba; Masselink, W Ted; Vucković, Jelena

2009-12-07

We demonstrate second harmonic generation in photonic crystal nanocavities fabricated in the semiconductor gallium phosphide. We observe second harmonic radiation at 750 nm with input powers of only nanowatts coupled to the cavity and conversion effciency P(out)/P(2)(in,coupled)=430%/W. The large electronic band gap of GaP minimizes absorption loss, allowing effcient conversion. Our results are promising for integrated, low-power light sources and on-chip reduction of input power in other nonlinear processes.

The efficiency of ultrasonic oscillations transfer into the load

NASA Astrophysics Data System (ADS)

Abramov, O. V.; Abramov, V. O.; Mullakaev, M. S.; Artem'ev, V. V.

2009-11-01

The results of ultrasonic action to the substances have been presented. It is examined, the correlation between the electrical parameters of ultrasonic equipment and acoustic performances of the ultrasonic field in treating the medium, the efficiency of ultrasonic technological facility, and the peculiarities of oscillations introduced into the load under cavitation development. The correlation between the acoustic powers of oscillations securing the needed level of cavitation and desired technological effect, and the electrical parameters of the ultrasonic facility, first of all, the power, is established. The peculiarities of cavitation development in liquids with different physical-chemical properties (including the molten low-melting metals) have been studied, and the acoustic power of oscillations introduced into the load under input variation of electric power to the generator has been also estimated.

Radiation characteristics of input power from surface wave sustained plasma antenna

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

Naito, T., E-mail: Naito.Teruki@bc.MitsubishiElectric.co.jp; Yamaura, S.; Fukuma, Y.

This paper reports radiation characteristics of input power from a surface wave sustained plasma antenna investigated theoretically and experimentally, especially focusing on the power consumption balance between the plasma generation and the radiation. The plasma antenna is a dielectric tube filled with argon and small amount of mercury, and the structure is a basic quarter wavelength monopole antenna at 2.45 GHz. Microwave power at 2.45 GHz is supplied to the plasma antenna. The input power is partially consumed to sustain the plasma, and the remaining part is radiated as a signal. The relationship between the antenna gain and the input powermore » is obtained by an analytical derivation and numerical simulations. As a result, the antenna gain is kept at low values, and most of the input power is consumed to increase the plasma volume until the tube is filled with the plasma whose electron density is higher than the critical electron density required for sustaining the surface wave. On the other hand, the input power is consumed to increase the electron density after the tube is fully filled with the plasma, and the antenna gain increases with increasing the electron density. The dependence of the antenna gain on the electron density is the same as that of a plasma antenna sustained by a DC glow discharge. These results are confirmed by experimental results of the antenna gain and radiation patterns. The antenna gain of the plasma is a few dB smaller than that of the identical metal antenna. The antenna gain of the plasma antenna is sufficient for the wireless communication, although it is difficult to substitute the plasma antenna for metal antennas completely. The plasma antenna is suitable for applications having high affinity with the plasma characteristics such as low interference and dynamic controllability.« less

On the use of an Arduino-based controller to control the charging process of a wind turbine

NASA Astrophysics Data System (ADS)

Mahmuddin, Faisal; Yusran, Ahmad Muhtam; Klara, Syerly

2017-02-01

In order to avoid an excessive charging voltage which can damage power storage when converting wind energy using a turbine, it is necessary to control the charging voltage of the turbine generator. In the present study, a charging controller which uses an Arduino microcontroller, is designed. 3 (three) indicator lights are installed to indicate the battery charging process, power diversion to dummy load and battery power level. The performance of the designed controller is evaluated by simulating 3 cases. In this simulation, a battery with maximum voltage of 12.4 V is used. Case 1 is performed with input voltage equals the one set in Arduino which is 10 V. In this case, the battery is charged up to 10.8 V. In case 2, the input voltage is 13 V while the maximum voltage set in Arduino is also 13 V. In this case, the battery is charged up to maximum voltage of the battery. Moreover, the dummy load indicator is ON and charging indicator is OFF after the maximum charging voltage is reached because the electricity is flowed to the dummy load. In the final case, the input voltage is set to be 16 V while the maximum voltage set in Arduino is 13 V. In this case, the charging indicator is OFF and dummy load indicator is ON which means that the Arduino has successfully switched the power to be flowed to dummy load. From the 3 (three) cases, it can be concluded that the designed controller works perfectly to control the charging process of the wind turbine. Moreover, the charging time needed in each case can also be determined.

Optimization of light quality from color mixing light-emitting diode systems for general lighting

NASA Astrophysics Data System (ADS)

Thorseth, Anders

2012-03-01

Given the problem of metamerisms inherent in color mixing in light-emitting diode (LED) systems with more than three distinct colors, a method for optimizing the spectral output of multicolor LED system with regards to standardized light quality parameters has been developed. The composite spectral power distribution from the LEDs are simulated using spectral radiometric measurements of single commercially available LEDs for varying input power, to account for the efficiency droop and other non-linear effects in electrical power vs. light output. The method uses electrical input powers as input parameters in a randomized steepest decent optimization. The resulting spectral power distributions are evaluated with regard to the light quality using the standard characteristics: CIE color rendering index, correlated color temperature and chromaticity distance. The results indicate Pareto optimal boundaries for each system, mapping the capabilities of the simulated lighting systems with regard to the light quality characteristics.

Hybrid powertrain system including smooth shifting automated transmission

DOEpatents

Beaty, Kevin D.; Nellums, Richard A.

2006-10-24

A powertrain system is provided that includes a prime mover and a change-gear transmission having an input, at least two gear ratios, and an output. The powertrain system also includes a power shunt configured to route power applied to the transmission by one of the input and the output to the other one of the input and the output. A transmission system and a method for facilitating shifting of a transmission system are also provided.

Control oriented concentrating solar power (CSP) plant model and its applications

NASA Astrophysics Data System (ADS)

Luo, Qi

Solar receivers in concentrating solar thermal power plants (CSP) undergo over 10,000 start-ups and shutdowns, and over 25,000 rapid rate of change in temperature on receivers due to cloud transients resulting in performance degradation and material fatigue in their expected lifetime of over 30 years. The research proposes to develop a three-level controller that uses multi-input-multi-output (MIMO) control technology to minimize the effect of these disturbances, improve plant performance, and extend plant life. The controller can be readily installed on any vendor supplied state-of-the-art control hardware. We propose a three-level controller architecture using multi-input-multi-output (MIMO) control for CSP plants that can be implemented on existing plants to improve performance, reliability, and extend the life of the plant. This architecture optimizes the performance on multiple time scalesreactive level (regulation to temperature set points), tactical level (adaptation of temperature set points), and strategic level (trading off fatigue life due to thermal cycling and current production). This controller unique to CSP plants operating at temperatures greater than 550 °C, will make CSPs competitive with conventional power plants and contribute significantly towards the Sunshot goal of 0.06/kWh(e), while responding with agility to both market dynamics and changes in solar irradiance such as due to passing clouds. Moreover, our development of control software with performance guarantees will avoid early stage failures and permit smooth grid integration of the CSP power plants. The proposed controller can be implemented with existing control hardware infrastructure with little or no additional equipment. In the thesis, we demonstrate a dynamics model of CSP, of which different components are modelled with different time scales. We also show a real time control strategy of CSP control oriented model in steady state. Furthermore, we shown different controllers design for disturbance rejection and reference tracking to handle complex receiver dynamics under system disturbance and measurement noise. At last, we show different applications of this control oriented CSP model including life cycle enhancement and electricity load forecasting using both neural network and regression tree.

Static inverter with synchronous output waveform synthesized by time-optimal-response feedback

NASA Technical Reports Server (NTRS)

Kernick, A.; Stechschulte, D. L.; Shireman, D. W.

1976-01-01

Time-optimal-response 'bang-bang' or 'bang-hang' technique, using four feedback control loops, synthesizes static-inverter sinusoidal output waveform by self-oscillatory but yet synchronous pulse-frequency-modulation (SPFM). A single modular power stage per phase of ac output entails the minimum of circuit complexity while providing by feedback synthesis individual phase voltage regulation, phase position control and inherent compensation simultaneously for line and load disturbances. Clipped sinewave performance is described under off-limit load or input voltage conditions. Also, approaches to high power levels, 3-phase arraying and parallel modular connection are given.

Writing and compiling code into biochemistry.

PubMed

Shea, Adam; Fett, Brian; Riedel, Marc D; Parhi, Keshab

2010-01-01

This paper presents a methodology for translating iterative arithmetic computation, specified as high-level programming constructs, into biochemical reactions. From an input/output specification, we generate biochemical reactions that produce output quantities of proteins as a function of input quantities performing operations such as addition, subtraction, and scalar multiplication. Iterative constructs such as "while" loops and "for" loops are implemented by transferring quantities between protein types, based on a clocking mechanism. Synthesis first is performed at a conceptual level, in terms of abstract biochemical reactions - a task analogous to high-level program compilation. Then the results are mapped onto specific biochemical reactions selected from libraries - a task analogous to machine language compilation. We demonstrate our approach through the compilation of a variety of standard iterative functions: multiplication, exponentiation, discrete logarithms, raising to a power, and linear transforms on time series. The designs are validated through transient stochastic simulation of the chemical kinetics. We are exploring DNA-based computation via strand displacement as a possible experimental chassis.

Dosimetry of a set-up for the exposure of newborn mice to 2.45-GHZ WiFi frequencies.

PubMed

Pinto, R; Lopresto, V; Galloni, P; Marino, C; Mancini, S; Lodato, R; Pioli, C; Lovisolo, G A

2010-08-01

This work describes the dosimetry of a two waveguide cell system designed to expose newborn mice to electromagnetic fields associated with wireless fidelity signals in the frequency band of 2.45 GHz. The dosimetric characterisation of the exposure system was performed both numerically and experimentally. Specific measures were adopted with regard to the increase in both weight and size of the biological target during the exposure period. The specific absorption rate (SAR, W kg(-1)) for 1 W of input power vs. weight curve was assessed. The curve evidenced an SAR pattern varying from <1 W kg(-1) to >6 W kg(-1) during the first 5 weeks of the life of mice, with a peak resonance phenomenon at a weight around 5 g. This curve was used to set the appropriate level of input power during experimental sessions to expose the growing mice to a defined and constant dose.

Compound hydraulic shear-modulated vortex amplifiers

NASA Technical Reports Server (NTRS)

Goldschmied, F. R.

1977-01-01

A novel two-stage shear-modulated hydraulic vortex amplifier (U.S. patent 3,520,317) has been fabricated and put through preliminary steady-state testing at the 1000 psi supply pressure level with flows up to 15 gpm. The invention comprises a conventional fluidic vortex power stage and a shear-modulated pilot stage. In the absence of any mechanical moving parts, water may be used as the hydraulic medium thus opening the way to many underseas applications. At blocked load, a control input from 0 to 150 psi was required to achieve an output from 0 to 900 psi; at wide-open load, a control input of 0 to 120 psi was needed to achieve an output from 0 to 15 gpm. The power stage has been found unsuitable for the proportional control mode because of its nonlinear performance in the intermediate load range and because of strong pressure fluctuations (plus or minus 150 psi) in the intermediate control range. The addition of the shear-modulated pilot stage improves intermediate load linearity.

Scanned Laser Illuminator/Receiver

DTIC Science & Technology

1976-11-01

0.21/cm | | Optical Power 20 Watts i input I Optical Power 100 Watts | output ! Input Power 10 kW The oscillator ...8217.rectional due to the oscillating mirror. Again, con- siderable optical magnification is provided between object space and the scan mirror to minimize the...for a 100W (14) R. A. McClatchey, et al, " Optical Properties of the Atmosphere (Third Edition)," Air Force Cambridge Research Laboratories, Tech

Active Vibration Control for Helicopter Interior Noise Reduction Using Power Minimization

NASA Technical Reports Server (NTRS)

Mendoza, J.; Chevva, K.; Sun, F.; Blanc, A.; Kim, S. B.

2014-01-01

This report describes work performed by United Technologies Research Center (UTRC) for NASA Langley Research Center (LaRC) under Contract NNL11AA06C. The objective of this program is to develop technology to reduce helicopter interior noise resulting from multiple gear meshing frequencies. A novel active vibration control approach called Minimum Actuation Power (MAP) is developed. MAP is an optimal control strategy that minimizes the total input power into a structure by monitoring and varying the input power of controlling sources. MAP control was implemented without explicit knowledge of the phasing and magnitude of the excitation sources by driving the real part of the input power from the controlling sources to zero. It is shown that this occurs when the total mechanical input power from the excitation and controlling sources is a minimum. MAP theory is developed for multiple excitation sources with arbitrary relative phasing for single or multiple discrete frequencies and controlled by a single or multiple controlling sources. Simulations and experimental results demonstrate the feasibility of MAP for structural vibration reduction of a realistic rotorcraft interior structure. MAP control resulted in significant average global vibration reduction of a single frequency and multiple frequency excitations with one controlling actuator. Simulations also demonstrate the potential effectiveness of the observed vibration reductions on interior radiated noise.

Advanced insulated gate bipolar transistor gate drive

DOEpatents

Short, James Evans [Monongahela, PA; West, Shawn Michael [West Mifflin, PA; Fabean, Robert J [Donora, PA

2009-08-04

A gate drive for an insulated gate bipolar transistor (IGBT) includes a control and protection module coupled to a collector terminal of the IGBT, an optical communications module coupled to the control and protection module, a power supply module coupled to the control and protection module and an output power stage module with inputs coupled to the power supply module and the control and protection module, and outputs coupled to a gate terminal and an emitter terminal of the IGBT. The optical communications module is configured to send control signals to the control and protection module. The power supply module is configured to distribute inputted power to the control and protection module. The control and protection module outputs on/off, soft turn-off and/or soft turn-on signals to the output power stage module, which, in turn, supplies a current based on the signal(s) from the control and protection module for charging or discharging an input capacitance of the IGBT.

The Impact of School Level and Socioeconomic Variables on the Adoption of School Community Based Management in Hawaii's Public Schools.

ERIC Educational Resources Information Center

O'Hora-Weir, M. Eileen; Ganopole, Selina

The School Community Based Management (SCBM) process for the Hawaii public school system, legislated in 1989, elicits input from administrators, teachers, support staff, parents, students, and community members. SCBM shifts some of the decision making powers to the school and can be adopted by a school on a voluntary basis. This study develops a…

Systems and methods for compensating for electrical converter nonlinearities

DOEpatents

Perisic, Milun; Ransom, Ray M.; Kajouke, Lateef A.

2013-06-18

Systems and methods are provided for delivering energy from an input interface to an output interface. An electrical system includes an input interface, an output interface, an energy conversion module coupled between the input interface and the output interface, and a control module. The control module determines a duty cycle control value for operating the energy conversion module to produce a desired voltage at the output interface. The control module determines an input power error at the input interface and adjusts the duty cycle control value in a manner that is influenced by the input power error, resulting in a compensated duty cycle control value. The control module operates switching elements of the energy conversion module to deliver energy to the output interface with a duty cycle that is influenced by the compensated duty cycle control value.

Automatic insulation resistance testing apparatus

DOEpatents

Wyant, Francis J.; Nowlen, Steven P.; Luker, Spencer M.

2005-06-14

An apparatus and method for automatic measurement of insulation resistances of a multi-conductor cable. In one embodiment of the invention, the apparatus comprises a power supply source, an input measuring means, an output measuring means, a plurality of input relay controlled contacts, a plurality of output relay controlled contacts, a relay controller and a computer. In another embodiment of the invention the apparatus comprises a power supply source, an input measuring means, an output measuring means, an input switching unit, an output switching unit and a control unit/data logger. Embodiments of the apparatus of the invention may also incorporate cable fire testing means. The apparatus and methods of the present invention use either voltage or current for input and output measured variables.

47 CFR 73.1820 - Station log.

Code of Federal Regulations, 2011 CFR

2011-10-01

... values): (A) Common point current. (B) When the operating power is determined by the indirect method, the efficiency factor F and either the product of the final amplifier input voltage and current or the calculated antenna input power. See § 73.51(e). (C) Antenna monitor phase or phase deviation indications. (D) Antenna...

Effects of vibration and shock on the performance of gas-bearing space-power Brayton cycle turbomachinery. Part 3: Sinusoidal and random vibration data reduction and evaluation, and random vibration probability analysis

NASA Technical Reports Server (NTRS)

Tessarzik, J. M.; Chiang, T.; Badgley, R. H.

1973-01-01

The random vibration response of a gas bearing rotor support system has been experimentally and analytically investigated in the amplitude and frequency domains. The NASA Brayton Rotating Unit (BRU), a 36,000 rpm, 10 KWe turbogenerator had previously been subjected in the laboratory to external random vibrations, and the response data recorded on magnetic tape. This data has now been experimentally analyzed for amplitude distribution and magnetic tape. This data has now been experimentally analyzed for amplitude distribution and frequency content. The results of the power spectral density analysis indicate strong vibration responses for the major rotor-bearing system components at frequencies which correspond closely to their resonant frequencies obtained under periodic vibration testing. The results of amplitude analysis indicate an increasing shift towards non-Gaussian distributions as the input level of external vibrations is raised. Analysis of axial random vibration response of the BRU was performed by using a linear three-mass model. Power spectral densities, the root-mean-square value of the thrust bearing surface contact were calculated for specified input random excitation.

RF-DC converter for HF RFID sensing applications powered by a near-field loop antenna

NASA Astrophysics Data System (ADS)

Colella, R.; Pasca, M.; Catarinucci, L.; Tarricone, L.; D'Amico, S.

2016-07-01

In this paper, an RF-DC converter operating at 13.56 MHz (HF radio frequency identification (RFID) frequency band) is presented. Its architecture provides RF to load isolation, reducing the losses due to the reverse saturation current and improving the sensitivity. Fed by a loop antenna, the RF-DC converter is made by a Dickson's RF-DC rectifier and an additional Pelliconi's charge pump driven by a fully integrated 50 kHz ring oscillator realized using an application-specific integrated circuit (ASIC). The input RF signal from the reader is converted to DC supply voltage and stored on a 1 μF capacitor. Mathematical model of the converter is developed and verified through measurements. Silicon prototypes of the ASIC have been realized in 350 nm complementary metal-oxide semiconductor technology. Measurements have been done on 10 different samples showing an output voltage in the range of 0.5 V-3.11 V in correspondence of an RF input signal power in the range of -19 dBm-0 dBm. These output voltage levels are suitable to power HF RFID sensing platforms and sensor nodes of body sensor networks.

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.

Identifying the location of the OMP separatrix in DIII-D using power accounting

DOE PAGES

Stangeby, Peter C.; Canik, John M.; Elder, J. D.; ...

2015-08-07

In order to identify reliable scalings for the scrape-off layer (SOL) power width it is necessary to know the location of the separatrix in divertor tokamaks as accurately as possible, specifically its location at the outside midplane (OMP) the standard reference location. Two methods are described which use power accounting to improve the accuracy of identifying the location of the OMP separatrix. The first uses the infrared-measured deposited power profile at the outer target as the primary input, the 'more » $$P_{{\\rm SOL}}^{{\\rm exhaust}}$$ method'. The second uses the measured power input to the SOL, obtained by subtracting the power radiated from inside the separatrix from the total heating power, the ' $$P_{{\\rm SOL}}^{{\\rm input}}$$ method'. Furthermore, these two power accounting methods are illustrated with the examples of 21 H-mode DIII-D discharges. High spatial resolution Thomson scattering measured profiles of ne and Te for the main SOL near the OMP are also used as primary input to the analysis; only between-edge localized mode data are used here. The Thomson profiles are used to calculate the electron parallel conducted heat flux profiles which are then matched to the measured $$P_{{\\rm SOL}}^{{\\rm exhaust}}$$ and $$P_{{\\rm SOL}}^{{\\rm input}}$$ by adjusting the location of the OMP separatrix relative to that of the Thomson data. For these attached discharges, it is found that the values of $$R_{{\\rm sep}}^{{\\rm omp}}$$ given by the two power accounting methods agree to within ~1 mm of each other and also to within ~1 mm of the values given by the 'standard DIII-D method' described by Porter et al (1998 Phys. Plasmas 5 1410). Lastly, the shifted $$R_{{\\rm sep}}^{{\\rm omp}}$$ results in only modest changes to the values of ne and Te at the OMP separatrix relative to the 'standard' values, increasing $$n_{{\\rm e}}^{{\\rm sep}}$$ by 8% and $$T_{{\\rm e}}^{{\\rm sep}}$$ by 20%.« less

The Conditional Entropy Power Inequality for Bosonic Quantum Systems

NASA Astrophysics Data System (ADS)

De Palma, Giacomo; Trevisan, Dario

2018-06-01

We prove the conditional Entropy Power Inequality for Gaussian quantum systems. This fundamental inequality determines the minimum quantum conditional von Neumann entropy of the output of the beam-splitter or of the squeezing among all the input states where the two inputs are conditionally independent given the memory and have given quantum conditional entropies. We also prove that, for any couple of values of the quantum conditional entropies of the two inputs, the minimum of the quantum conditional entropy of the output given by the conditional Entropy Power Inequality is asymptotically achieved by a suitable sequence of quantum Gaussian input states. Our proof of the conditional Entropy Power Inequality is based on a new Stam inequality for the quantum conditional Fisher information and on the determination of the universal asymptotic behaviour of the quantum conditional entropy under the heat semigroup evolution. The beam-splitter and the squeezing are the central elements of quantum optics, and can model the attenuation, the amplification and the noise of electromagnetic signals. This conditional Entropy Power Inequality will have a strong impact in quantum information and quantum cryptography. Among its many possible applications there is the proof of a new uncertainty relation for the conditional Wehrl entropy.

Retention of Antibacterial Activity in Geranium Plasma Polymer Thin Films

PubMed Central

Al-Jumaili, Ahmed; Bazaka, Kateryna

2017-01-01

Bacterial colonisation of biomedical devices demands novel antibacterial coatings. Plasma-enabled treatment is an established technique for selective modification of physicochemical characteristics of the surface and deposition of polymer thin films. We investigated the retention of inherent antibacterial activity in geranium based plasma polymer thin films. Attachment and biofilm formation by Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli was significantly reduced on the surfaces of samples fabricated at 10 W radio frequency (RF) power, compared to that of control or films fabricated at higher input power. This was attributed to lower contact angle and retention of original chemical functionality in the polymer films fabricated under low input power conditions. The topography of all surfaces was uniform and smooth, with surface roughness of 0.18 and 0.69 nm for films fabricated at 10 W and 100 W, respectively. Hardness and elastic modules of films increased with input power. Independent of input power, films were optically transparent within the visible wavelength range, with the main absorption at ~290 nm and optical band gap of ~3.6 eV. These results suggest that geranium extract-derived polymers may potentially be used as antibacterial coatings for contact lenses. PMID:28902134

The Conditional Entropy Power Inequality for Bosonic Quantum Systems

NASA Astrophysics Data System (ADS)

De Palma, Giacomo; Trevisan, Dario

2018-01-01

We prove the conditional Entropy Power Inequality for Gaussian quantum systems. This fundamental inequality determines the minimum quantum conditional von Neumann entropy of the output of the beam-splitter or of the squeezing among all the input states where the two inputs are conditionally independent given the memory and have given quantum conditional entropies. We also prove that, for any couple of values of the quantum conditional entropies of the two inputs, the minimum of the quantum conditional entropy of the output given by the conditional Entropy Power Inequality is asymptotically achieved by a suitable sequence of quantum Gaussian input states. Our proof of the conditional Entropy Power Inequality is based on a new Stam inequality for the quantum conditional Fisher information and on the determination of the universal asymptotic behaviour of the quantum conditional entropy under the heat semigroup evolution. The beam-splitter and the squeezing are the central elements of quantum optics, and can model the attenuation, the amplification and the noise of electromagnetic signals. This conditional Entropy Power Inequality will have a strong impact in quantum information and quantum cryptography. Among its many possible applications there is the proof of a new uncertainty relation for the conditional Wehrl entropy.

Diode amplifier of modulated optical beam power

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

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

2014-11-30

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

Power characteristics in GMAW: Experimental and numerical investigation

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

Joensson, P.G.; Szekely, J.; Madigan, R.B.

1995-03-01

The voltage and power distributions in gas metal arc welding (GMAW) were studied both experimentally and numerically. The principal voltage drop takes place in the arc, which also constitutes the dominant power contribution. Within the arc, the dominating voltage contributions are from the arc column and the cathode fall, while the anode fall and the electrode regions are less significant. The power input to the arc column increases with both increasing current and increasing arc length. These results indicate that it is critical to control the arc length in order to control the power input to the system.

Measuring case-mix complexity of tertiary care hospitals using DRGs.

PubMed

Park, Hayoung; Shin, Youngsoo

2004-02-01

The objectives of the study were to develop a model that measures and evaluates case-mix complexity of tertiary care hospitals, and to examine the characteristics of such a model. Physician panels defined three classes of case complexity and assigned disease categories represented by Adjacent Diagnosis Related Groups (ADRGs) to one of three case complexity classes. Three types of scores, indicating proportions of inpatients in each case complexity class standardized by the proportions at the national level, were defined to measure the case-mix complexity of a hospital. Discharge information for about 10% of inpatient episodes at 85 hospitals with bed size larger than 400 and their input structure and research and education activity were used to evaluate the case-mix complexity model. Results show its power to predict hospitals with the expected functions of tertiary care hospitals, i.e. resource intensive care, expensive input structure, and high levels of research and education activities.

Transcriptome Analysis at the Single-Cell Level Using SMART Technology.

PubMed

Fish, Rachel N; Bostick, Magnolia; Lehman, Alisa; Farmer, Andrew

2016-10-10

RNA sequencing (RNA-seq) is a powerful method for analyzing cell state, with minimal bias, and has broad applications within the biological sciences. However, transcriptome analysis of seemingly homogenous cell populations may in fact overlook significant heterogeneity that can be uncovered at the single-cell level. The ultra-low amount of RNA contained in a single cell requires extraordinarily sensitive and reproducible transcriptome analysis methods. As next-generation sequencing (NGS) technologies mature, transcriptome profiling by RNA-seq is increasingly being used to decipher the molecular signature of individual cells. This unit describes an ultra-sensitive and reproducible protocol to generate cDNA and sequencing libraries directly from single cells or RNA inputs ranging from 10 pg to 10 ng. Important considerations for working with minute RNA inputs are given. © 2016 by John Wiley & Sons, Inc. Copyright © 2016 John Wiley & Sons, Inc.

Energetics of the magnetosphere

NASA Technical Reports Server (NTRS)

Stern, D. P.

1980-01-01

The approximate magnitudes of several power inputs and energies associated with the Earth's magnetosphere will be derived. They include: Solar wind power impinging on the dayside magnetopause approximately 1.4 10 to the 13th power watt; power input to cross tail current approximately 3 10 to the 11th power watt; energy of moderate magnetic storm approximately 2 10 to the 15th power joule; power related to the flow of j approximately 1 to 3 10 to the 11th power watt; average power deposited by the aurora approximately 2 10 to the 10th power watt. Stored magnetic energy: released in a substorm approximately 1.5 10 to the 14th power joule. Compared to the above, the rate at which energy is released locally in magnetospheric regions where magnetic merging occurs is probably small. Merging is essential, however, for the existence of open field lines, which provide the most likely explanation for some major energy inputs listed here. Merging is also required if part of the open flux of the tail lobes is converted into closed flux, as seems to happen during substorms. Again, most of the energy release becomes evident only beyond the merging region, though some particles may gain appreciable energy in that region itself, if the plasma sheet is completely squeezed out and the high latitude lobes interact directly.

Frequency-band signatures of visual responses to naturalistic input in ferret primary visual cortex during free viewing.

PubMed

Sellers, Kristin K; Bennett, Davis V; Fröhlich, Flavio

2015-02-19

Neuronal firing responses in visual cortex reflect the statistics of visual input and emerge from the interaction with endogenous network dynamics. Artificial visual stimuli presented to animals in which the network dynamics were constrained by anesthetic agents or trained behavioral tasks have provided fundamental understanding of how individual neurons in primary visual cortex respond to input. In contrast, very little is known about the mesoscale network dynamics and their relationship to microscopic spiking activity in the awake animal during free viewing of naturalistic visual input. To address this gap in knowledge, we recorded local field potential (LFP) and multiunit activity (MUA) simultaneously in all layers of primary visual cortex (V1) of awake, freely viewing ferrets presented with naturalistic visual input (nature movie clips). We found that naturalistic visual stimuli modulated the entire oscillation spectrum; low frequency oscillations were mostly suppressed whereas higher frequency oscillations were enhanced. In average across all cortical layers, stimulus-induced change in delta and alpha power negatively correlated with the MUA responses, whereas sensory-evoked increases in gamma power positively correlated with MUA responses. The time-course of the band-limited power in these frequency bands provided evidence for a model in which naturalistic visual input switched V1 between two distinct, endogenously present activity states defined by the power of low (delta, alpha) and high (gamma) frequency oscillatory activity. Therefore, the two mesoscale activity states delineated in this study may define the degree of engagement of the circuit with the processing of sensory input. Copyright © 2014 Elsevier B.V. All rights reserved.

Enhanced visible light generation in an active microcavity via third-harmonic conversion beyond the non-depletion approximation

NASA Astrophysics Data System (ADS)

Yu, Rong; Ding, Chunling; Wang, Jiangpeng; Zhang, Duo

2017-12-01

We explore the possibility of using an active doubly resonant microtoroid resonator to produce high-efficiency third-harmonic generation (THG) by exploiting optical third-order nonlinearity. In a microresonator, the active fundamental mode is coherently driven with a continuous-wave input laser at the telecommunication wavelength (1550 nm), and then, the visible THG signal (517 nm) is monitored via an individual bus waveguide. We thoroughly compare our results with those obtained from the conventional passive (i.e., loss) microtoroid resonator by a systematic analysis and detailed numerical simulations based on the Heisenberg-Langevin equations of motion. It is shown that the achievable THG spectrum features an ultralow critical input power. The THG power transmission can be significantly enhanced by about three orders of magnitude at a low input power of 0.1 μ W as compared with the obtained results in the passive microtoroid resonator THG system. Moreover, the THG efficiency can reach up to 100% with optical critical input power as low as a few microwatts. In turn, the analytical expressions of the critical intracavity intensity of the light in the microcavity, the critical input pump power, and the maximum THG efficiency are obtained. The enhanced THG power transmission and high conversion efficiency are attributed to a gain-induced loss compensation in the microtoroid resonator, reducing the effective loss felt by the resonator photons. With state-of-the art technologies in the field of solid-state resonators, including but not limited to microtoroids, the proposed THG scheme is experimentally realizable.

Computer programs for producing single-event aircraft noise data for specific engine power and meteorological conditions for use with USAF (United States Air Force) community noise model (NOISEMAP)

NASA Astrophysics Data System (ADS)

Mohlman, H. T.

1983-04-01

The Air Force community noise prediction model (NOISEMAP) is used to describe the aircraft noise exposure around airbases and thereby aid airbase planners to minimize exposure and prevent community encroachment which could limit mission effectiveness of the installation. This report documents two computer programs (OMEGA 10 and OMEGA 11) which were developed to prepare aircraft flight and ground runup noise data for input to NOISEMAP. OMEGA 10 is for flight operations and OMEGA 11 is for aircraft ground runups. All routines in each program are documented at a level useful to a programmer working with the code or a reader interested in a general overview of what happens within a specific subroutine. Both programs input normalized, reference aircraft noise data; i.e., data at a standard reference distance from the aircraft, for several fixed engine power settings, a reference airspeed and standard day meteorological conditions. Both programs operate on these normalized, reference data in accordance with user-defined, non-reference conditions to derive single-event noise data for 22 distances (200 to 25,000 feet) in a variety of physical and psycho-acoustic metrics. These outputs are in formats ready for input to NOISEMAP.

Intermediate conductance calcium-activated potassium channels modulate summation of parallel fiber input in cerebellar Purkinje cells.

PubMed

Engbers, Jordan D T; Anderson, Dustin; Asmara, Hadhimulya; Rehak, Renata; Mehaffey, W Hamish; Hameed, Shahid; McKay, Bruce E; Kruskic, Mirna; Zamponi, Gerald W; Turner, Ray W

2012-02-14

Encoding sensory input requires the expression of postsynaptic ion channels to transform key features of afferent input to an appropriate pattern of spike output. Although Ca(2+)-activated K(+) channels are known to control spike frequency in central neurons, Ca(2+)-activated K(+) channels of intermediate conductance (KCa3.1) are believed to be restricted to peripheral neurons. We now report that cerebellar Purkinje cells express KCa3.1 channels, as evidenced through single-cell RT-PCR, immunocytochemistry, pharmacology, and single-channel recordings. Furthermore, KCa3.1 channels coimmunoprecipitate and interact with low voltage-activated Cav3.2 Ca(2+) channels at the nanodomain level to support a previously undescribed transient voltage- and Ca(2+)-dependent current. As a result, subthreshold parallel fiber excitatory postsynaptic potentials (EPSPs) activate Cav3 Ca(2+) influx to trigger a KCa3.1-mediated regulation of the EPSP and subsequent after-hyperpolarization. The Cav3-KCa3.1 complex provides powerful control over temporal summation of EPSPs, effectively suppressing low frequencies of parallel fiber input. KCa3.1 channels thus contribute to a high-pass filter that allows Purkinje cells to respond preferentially to high-frequency parallel fiber bursts characteristic of sensory input.

Apparatus for Controlling Low Power Voltages in Space Based Processing Systems

NASA Technical Reports Server (NTRS)

Petrick, David J. (Inventor)

2017-01-01

A low power voltage control circuit for use in space missions includes a switching device coupled between an input voltage and an output voltage. The switching device includes a control input coupled to an enable signal, wherein the control input is configured to selectively turn the output voltage on or off based at least in part on the enable signal. A current monitoring circuit is coupled to the output voltage and configured to produce a trip signal, wherein the trip signal is active when a load current flowing through the switching device is determined to exceed a predetermined threshold and is inactive otherwise. The power voltage control circuit is constructed of space qualified components.

Triboelectric generators and sensors

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

Wang, Zhong Lin; Wang, Sihong; Zhu, Guang

2017-10-17

A triboelectric power system includes a triboelectric generator, a rechargeable energy storage unit and a power management circuit. The rechargeable energy storage unit is associated to the triboelectric generator. The power management circuit is configured to receive an input current from the triboelectric generator and to deliver an output current corresponding to the input current to the rechargeable battery so that the output current has a current direction and a voltage that will recharge the rechargeable battery.

Regulation control and energy management scheme for wireless power transfer

DOEpatents

Miller, John M.

2015-12-29

Power transfer rate at a charging facility can be maximized by employing a feedback scheme. The state of charge (SOC) and temperature of the regenerative energy storage system (RESS) pack of a vehicle is monitored to determine the load due to the RESS pack. An optimal frequency that cancels the imaginary component of the input impedance for the output signal from a grid converter is calculated from the load of the RESS pack, and a frequency offset f* is made to the nominal frequency f.sub.0 of the grid converter output based on the resonance frequency of a magnetically coupled circuit. The optimal frequency can maximize the efficiency of the power transfer. Further, an optimal grid converter duty ratio d* can be derived from the charge rate of the RESS pack. The grid converter duty ratio d* regulates wireless power transfer (WPT) power level.

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

Current fluctuations in quantum absorption refrigerators

NASA Astrophysics Data System (ADS)

Segal, Dvira

2018-05-01

Absorption refrigerators transfer thermal energy from a cold bath to a hot bath without input power by utilizing heat from an additional "work" reservoir. Particularly interesting is a three-level design for a quantum absorption refrigerator, which can be optimized to reach the maximal (Carnot) cooling efficiency. Previous studies of three-level chillers focused on the behavior of the averaged cooling current. Here, we go beyond that and study the full counting statistics of heat exchange in a three-level chiller model. We explain how to obtain the complete cumulant generating function of the refrigerator in a steady state, then derive a partial cumulant generating function, which yields closed-form expressions for both the averaged cooling current and its noise. Our analytical results and simulations are beneficial for the design of nanoscale engines and cooling systems far from equilibrium, with their performance optimized according to different criteria, efficiency, power, fluctuations, and dissipation.

Method for fabricating five-level microelectromechanical structures and microelectromechanical transmission formed

DOEpatents

Rodgers, M. Steven; Sniegowski, Jeffry J.; Miller, Samuel L.; McWhorter, Paul J.

2000-01-01

A process for forming complex microelectromechanical (MEM) devices having five layers or levels of polysilicon, including four structural polysilicon layers wherein mechanical elements can be formed, and an underlying polysilicon layer forming a voltage reference plane. A particular type of MEM device that can be formed with the five-level polysilicon process is a MEM transmission for controlling or interlocking mechanical power transfer between an electrostatic motor and a self-assembling structure (e.g. a hinged pop-up mirror for use with an incident laser beam). The MEM transmission is based on an incomplete gear train and a bridging set of gears that can be moved into place to complete the gear train to enable power transfer. The MEM transmission has particular applications as a safety component for surety, and for this purpose can incorporate a pin-in-maze discriminator responsive to a coded input signal.

Modality-specific spectral dynamics in response to visual and tactile sequential shape information processing tasks: An MEG study using multivariate pattern classification analysis.

PubMed

Gohel, Bakul; Lee, Peter; Jeong, Yong

2016-08-01

Brain regions that respond to more than one sensory modality are characterized as multisensory regions. Studies on the processing of shape or object information have revealed recruitment of the lateral occipital cortex, posterior parietal cortex, and other regions regardless of input sensory modalities. However, it remains unknown whether such regions show similar (modality-invariant) or different (modality-specific) neural oscillatory dynamics, as recorded using magnetoencephalography (MEG), in response to identical shape information processing tasks delivered to different sensory modalities. Modality-invariant or modality-specific neural oscillatory dynamics indirectly suggest modality-independent or modality-dependent participation of particular brain regions, respectively. Therefore, this study investigated the modality-specificity of neural oscillatory dynamics in the form of spectral power modulation patterns in response to visual and tactile sequential shape-processing tasks that are well-matched in terms of speed and content between the sensory modalities. Task-related changes in spectral power modulation and differences in spectral power modulation between sensory modalities were investigated at source-space (voxel) level, using a multivariate pattern classification (MVPC) approach. Additionally, whole analyses were extended from the voxel level to the independent-component level to take account of signal leakage effects caused by inverse solution. The modality-specific spectral dynamics in multisensory and higher-order brain regions, such as the lateral occipital cortex, posterior parietal cortex, inferior temporal cortex, and other brain regions, showed task-related modulation in response to both sensory modalities. This suggests modality-dependency of such brain regions on the input sensory modality for sequential shape-information processing. Copyright © 2016 Elsevier B.V. All rights reserved.

Optical power splitter for splitting high power light

DOEpatents

English, R.E. Jr.; Christensen, J.J.

1995-04-18

An optical power splitter for the distribution of high-power light energy has a plurality of prisms arranged about a central axis to form a central channel. The input faces of the prisms are in a common plane which is substantially perpendicular to the central axis. A beam of light which is substantially coaxial to the central axis is incident on the prisms and at least partially strikes a surface area of each prism input face. The incident beam also partially passes through the central channel. 5 figs.

User's manual for the Shuttle Electric Power System analysis computer program (SEPS), volume 2 of program documentation

NASA Technical Reports Server (NTRS)

Bains, R. W.; Herwig, H. A.; Luedeman, J. K.; Torina, E. M.

1974-01-01

The Shuttle Electric Power System Analysis SEPS computer program which performs detailed load analysis including predicting energy demands and consumables requirements of the shuttle electric power system along with parameteric and special case studies on the shuttle electric power system is described. The functional flow diagram of the SEPS program is presented along with data base requirements and formats, procedure and activity definitions, and mission timeline input formats. Distribution circuit input and fixed data requirements are included. Run procedures and deck setups are described.

Image-classification-based global dimming algorithm for LED backlights in LCDs

NASA Astrophysics Data System (ADS)

Qibin, Feng; Huijie, He; Dong, Han; Lei, Zhang; Guoqiang, Lv

2015-07-01

Backlight dimming can help LCDs reduce power consumption and improve CR. With fixed parameters, dimming algorithm cannot achieve satisfied effects for all kinds of images. The paper introduces an image-classification-based global dimming algorithm. The proposed classification method especially for backlight dimming is based on luminance and CR of input images. The parameters for backlight dimming level and pixel compensation are adaptive with image classifications. The simulation results show that the classification based dimming algorithm presents 86.13% power reduction improvement compared with dimming without classification, with almost same display quality. The prototype is developed. There are no perceived distortions when playing videos. The practical average power reduction of the prototype TV is 18.72%, compared with common TV without dimming.

RF digital-to-analog converter

DOEpatents

Conway, Patrick H.; Yu, David U. L.

1995-01-01

A digital-to analogue converter for producing an RF output signal proportional to a digital input word of N bits from an RF reference input, N being an integer greater or equal to 2. The converter comprises a plurality of power splitters, power combiners and a plurality of mixers or RF switches connected in a predetermined configuration.

Toward a Renewed Focus. Literacy in Early Language Programs

ERIC Educational Resources Information Center

Met, Mimi

2013-01-01

This article promotes literacy as a a powerful tool for learning new language. Although learners frequently think of comprehensible input as language that is heard, comprehensible input from print can also be accessed. Research has shown that reading has a powerful impact on language learning: much of the vocabulary that educated adults know has…

Series resonant converter with auxiliary winding turns: analysis, design and implementation

NASA Astrophysics Data System (ADS)

Lin, Bor-Ren

2018-05-01

Conventional series resonant converters have researched and applied for high-efficiency power units due to the benefit of its low switching losses. The main problems of series resonant converters are wide frequency variation and high circulating current. Thus, resonant converter is limited at narrow input voltage range and large input capacitor is normally adopted in commercial power units to provide the minimum hold-up time requirement when AC power is off. To overcome these problems, the resonant converter with auxiliary secondary windings are presented in this paper to achieve high voltage gain at low input voltage case such as hold-up time duration when utility power is off. Since the high voltage gain is used at low input voltage cased, the frequency variation of the proposed converter compared to the conventional resonant converter is reduced. Compared to conventional resonant converter, the hold-up time in the proposed converter is more than 40ms. The larger magnetising inductance of transformer is used to reduce the circulating current losses. Finally, a laboratory prototype is constructed and experiments are provided to verify the converter performance.

Enhanced Passive RF-DC Converter Circuit Efficiency for Low RF Energy Harvesting

PubMed Central

Chaour, Issam; Fakhfakh, Ahmed; Kanoun, Olfa

2017-01-01

For radio frequency energy transmission, the conversion efficiency of the receiver is decisive not only for reducing sending power, but also for enabling energy transmission over long and variable distances. In this contribution, we present a passive RF-DC converter for energy harvesting at ultra-low input power at 868 MHz. The novel converter consists of a reactive matching circuit and a combined voltage multiplier and rectifier. The stored energy in the input inductor and capacitance, during the negative wave, is conveyed to the output capacitance during the positive one. Although Dickson and Villard topologies have principally comparable efficiency for multi-stage voltage multipliers, the Dickson topology reaches a better efficiency within the novel ultra-low input power converter concept. At the output stage, a low-pass filter is introduced to reduce ripple at high frequencies in order to realize a stable DC signal. The proposed rectifier enables harvesting energy at even a low input power from −40 dBm for a resistive load of 50 kΩ. It realizes a significant improvement in comparison with state of the art solutions. PMID:28282910

Enhanced Passive RF-DC Converter Circuit Efficiency for Low RF Energy Harvesting.

PubMed

Chaour, Issam; Fakhfakh, Ahmed; Kanoun, Olfa

2017-03-09

For radio frequency energy transmission, the conversion efficiency of the receiver is decisive not only for reducing sending power, but also for enabling energy transmission over long and variable distances. In this contribution, we present a passive RF-DC converter for energy harvesting at ultra-low input power at 868 MHz. The novel converter consists of a reactive matching circuit and a combined voltage multiplier and rectifier. The stored energy in the input inductor and capacitance, during the negative wave, is conveyed to the output capacitance during the positive one. Although Dickson and Villard topologies have principally comparable efficiency for multi-stage voltage multipliers, the Dickson topology reaches a better efficiency within the novel ultra-low input power converter concept. At the output stage, a low-pass filter is introduced to reduce ripple at high frequencies in order to realize a stable DC signal. The proposed rectifier enables harvesting energy at even a low input power from -40 dBm for a resistive load of 50 kΩ. It realizes a significant improvement in comparison with state of the art solutions.

Heat input and accumulation for ultrashort pulse processing with high average power

NASA Astrophysics Data System (ADS)

Finger, Johannes; Bornschlegel, Benedikt; Reininghaus, Martin; Dohrn, Andreas; Nießen, Markus; Gillner, Arnold; Poprawe, Reinhart

2018-05-01

Materials processing using ultrashort pulsed laser radiation with pulse durations <10 ps is known to enable very precise processing with negligible thermal load. However, even for the application of picosecond and femtosecond laser radiation, not the full amount of the absorbed energy is converted into ablation products and a distinct fraction of the absorbed energy remains as residual heat in the processed workpiece. For low average power and power densities, this heat is usually not relevant for the processing results and dissipates into the workpiece. In contrast, when higher average powers and repetition rates are applied to increase the throughput and upscale ultrashort pulse processing, this heat input becomes relevant and significantly affects the achieved processing results. In this paper, we outline the relevance of heat input for ultrashort pulse processing, starting with the heat input of a single ultrashort laser pulse. Heat accumulation during ultrashort pulse processing with high repetition rate is discussed as well as heat accumulation for materials processing using pulse bursts. In addition, the relevance of heat accumulation with multiple scanning passes and processing with multiple laser spots is shown.

Heat suppression of the fiber coating on a cladding light stripper in high-power fiber laser.

PubMed

Yan, Ming-Jian; Wang, Zheng; Meng, Ling-Qiang; Yin, Lu; Han, Zhi-Gang; Shen, Hua; Wang, Hai-Lin; Zhu, Ri-Hong

2018-01-20

We present a theoretical model for the thermal effect of the fiber coating on a high-power cladding light stripper, which is fabricated by chemical etching. For the input and output of the fiber coating, a novel segmented corrosion method and increasing attenuation method are proposed for heat suppression, respectively. The relationship between the attenuation and temperature rise of the fiber coating at the output is experimentally demonstrated. The temperature distribution of the fiber coating at the input as well as the return light power caused by scattering are measured for the etched fiber with different surface roughness values. The results suggest that the rise in temperature is primarily caused by the scattering light propagating into the coating. Finally, an attenuation of 27 dB is achieved. At a room temperature of 23°C and input pump power of 438 W, the highest temperature of the input fiber coating decreases from 39.5°C to 27.9°C by segmented corrosion, and the temperature rise of the output fiber coating is close to 0.

UWB dual burst transmit driver

DOEpatents

Dallum, Gregory E [Livermore, CA; Pratt, Garth C [Discovery Bay, CA; Haugen, Peter C [Livermore, CA; Zumstein, James M [Livermore, CA; Vigars, Mark L [Livermore, CA; Romero, Carlos E [Livermore, CA

2012-04-17

A dual burst transmitter for ultra-wideband (UWB) communication systems generates a pair of precisely spaced RF bursts from a single trigger event. An input trigger pulse produces two oscillator trigger pulses, an initial pulse and a delayed pulse, in a dual trigger generator. The two oscillator trigger pulses drive a gated RF burst (power output) oscillator. A bias driver circuit gates the RF output oscillator on and off and sets the RF burst packet width. The bias driver also level shifts the drive signal to the level that is required for the RF output device.

Thermodynamic and experimental study on heat transfer mechanism of miniature loop heat pipe with water-copper nanofluid

NASA Astrophysics Data System (ADS)

Wang, Xiao-wu; Wan, Zhen-ping; Tang, Yong

2018-02-01

A miniature loop heat pipe (mLHP) is a promising device for heat dissipation of electronic products. Experimental study of heat transfer performance of an mLHP employing Cu-water nanofluid as working fluid was conducted. It is found that, when input power is above 25 W, the temperature differences between the evaporator wall and vapor of nanofluid, Te - Tv, and the total heat resistance of mLHP using nanofluid are always lower than those of mLHP using de-ionized water. The values of Te - Tv and total heat resistance of mLHP using nanofluid with concentration 1.5 wt. % are the lowest, while when the input power is 25 W, the values of Te - Tv and total heat resistance of mLHP using de-ionized water are even lower than those of mLHP using nanofluid with concentration 2.0 wt. %. At larger input power, the dominant interaction is collision between small bubbles and nanoparticles which can facilitate heat transfer. While at lower input power, nanoparticles adhere to the surface of large bubble. This does not benefit boiling heat transfer. For mLHP using nanofluid with larger concentration, for example 2.0%, the heat transfer may even be worse compared with using de-ionized water at lower input power. The special structure of the mLHP in this study, two separated chambers in the evaporator, produces an extra pressure difference and contributes to the heat transfer performance of the mLHP.

A double-stage start-up structure to limit the inrush current used in current mode charge pump

NASA Astrophysics Data System (ADS)

Cong, Liu; Xinquan, Lai; Hanxiao, Du; Yuan, Chi

2016-06-01

A double-stage start-up structure to limit the inrush current used in current-mode charge pump with wide input range, fixed output and multimode operation is presented in this paper. As a widely utilized power source implement, a Li-battery is always used as the power supply for chips. Due to the internal resistance, a potential drop will be generated at the input terminal of the chip with an input current. A false shut down with a low supply voltage will happen if the input current is too large, leading to the degradation of the Li-battery's service life. To solve this problem, the inrush current is limited by introducing a new start-up state. All of the circuits have been implemented with the NUVOTON 0.6 μm CMOS process. The measurement results show that the inrush current can be limited below 1 A within all input supply ranges, and the power efficiency is higher than the conventional structure. Project supported by the National Natural Science Foundation of China (No. 61106026).

Universal sensor interface module (USIM)

NASA Astrophysics Data System (ADS)

King, Don; Torres, A.; Wynn, John

1999-01-01

A universal sensor interface model (USIM) is being developed by the Raytheon-TI Systems Company for use with fields of unattended distributed sensors. In its production configuration, the USIM will be a multichip module consisting of a set of common modules. The common module USIM set consists of (1) a sensor adapter interface (SAI) module, (2) digital signal processor (DSP) and associated memory module, and (3) a RF transceiver model. The multispectral sensor interface is designed around a low-power A/D converted, whose input/output interface consists of: -8 buffered, sampled inputs from various devices including environmental, acoustic seismic and magnetic sensors. The eight sensor inputs are each high-impedance, low- capacitance, differential amplifiers. The inputs are ideally suited for interface with discrete or MEMS sensors, since the differential input will allow direct connection with high-impedance bridge sensors and capacitance voltage sources. Each amplifier is connected to a 22-bit (Delta) (Sigma) A/D converter to enable simultaneous samples. The low power (Delta) (Sigma) converter provides 22-bit resolution at sample frequencies up to 142 hertz (used for magnetic sensors) and 16-bit resolution at frequencies up to 1168 hertz (used for acoustic and seismic sensors). The video interface module is based around the TMS320C5410 DSP. It can provide sensor array addressing, video data input, data calibration and correction. The processor module is based upon a MPC555. It will be used for mode control, synchronization of complex sensors, sensor signal processing, array processing, target classification and tracking. Many functions of the A/D, DSP and transceiver can be powered down by using variable clock speeds under software command or chip power switches. They can be returned to intermediate or full operation by DSP command. Power management may be based on the USIM's internal timer, command from the USIM transceiver, or by sleep mode processing management. The low power detection mode is implemented by monitoring any of the sensor analog outputs at lower sample rates for detection over a software controllable threshold.

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

Hessell, Steven M.; Morris, Robert L.; McGrogan, Sean W.

A powertrain including an engine and torque machines is configured to transfer torque through a multi-mode transmission to an output member. A method for controlling the powertrain includes employing a closed-loop speed control system to control torque commands for the torque machines in response to a desired input speed. Upon approaching a power limit of a power storage device transferring power to the torque machines, power limited torque commands are determined for the torque machines in response to the power limit and the closed-loop speed control system is employed to determine an engine torque command in response to the desiredmore » input speed and the power limited torque commands for the torque machines.« less

Two terminal micropower radar sensor

DOEpatents

McEwan, Thomas E.

1995-01-01

A simple, low power ultra-wideband radar motion sensor/switch configuration connects a power source and load to ground. The switch is connected to and controlled by the signal output of a radar motion sensor. The power input of the motion sensor is connected to the load through a diode which conducts power to the motion sensor when the switch is open. A storage capacitor or rechargeable battery is connected to the power input of the motion sensor. The storage capacitor or battery is charged when the switch is open and powers the motion sensor when the switch is closed. The motion sensor and switch are connected between the same two terminals between the source/load and ground.

Two terminal micropower radar sensor

DOEpatents

McEwan, T.E.

1995-11-07

A simple, low power ultra-wideband radar motion sensor/switch configuration connects a power source and load to ground. The switch is connected to and controlled by the signal output of a radar motion sensor. The power input of the motion sensor is connected to the load through a diode which conducts power to the motion sensor when the switch is open. A storage capacitor or rechargeable battery is connected to the power input of the motion sensor. The storage capacitor or battery is charged when the switch is open and powers the motion sensor when the switch is closed. The motion sensor and switch are connected between the same two terminals between the source/load and ground. 3 figs.

Power optimization in logic isomers

NASA Technical Reports Server (NTRS)

Panwar, Ramesh; Rennels, David; Alkalaj, Leon

1993-01-01

Logic isomers are labeled, 2-isomorphic graphs that implement the same logic function. Logic isomers may have significantly different power requirements even though they have the same number of transistors in the implementation. The power requirements of the isomers depend on the transition activity of the input signals. The power requirements of isomorphic graph isomers of n-input NAND and NOR gates are shown. Choosing the less power-consuming isomer instead of the others can yield significant power savings. Experimental results on a ripple-carry adder are presented to show that the implementation using the least power-consuming isomers requires approximately 10 percent less power than the implementation using the most power-consuming isomers. Simulations of other random logic designs also confirm that designs using less power-consuming isomers can reduce the logic power demand by approximately 10 percent as compared to designs using more power-consuming isomers.

Plasma gun with coaxial powder feed and adjustable cathode

NASA Technical Reports Server (NTRS)

Zaplatynsky, Isidor (Inventor)

1991-01-01

An improved plasma gun coaxially injects particles of ceramic materials having high melting temperatures into the central portion of a plasma jet. This results in a more uniform and higher temperature and velocity distribution of the sprayed particles. The position of the cathode is adjustable to facilitate optimization of the performance of the gun wherein grains of the ceramic material are melted at lower power input levels.

Characterization of a spray torch and analysis of process parameters

NASA Astrophysics Data System (ADS)

Ramasamy, R.; Selvarajan, V.

1999-07-01

Anode for a non-transferred DC plasma spray torch was designed to improve electrothermal efficiency. A theoretical calculation was made for the electrothermal efficiency in a DC plasma torch operating with argon at atmospheric pressure with power level in the range of 5.2 20 kW using energy balance equations. ANOVA for the two level factorial design was done. Plasma gas flow rate, current intensity, nozzle diameter and length were found to influence the efficiency. The efficiency was found to decrease with increase in current intensity and nozzle length and to increase with increase in nozzle diameter and gas flow rate. The overall energy balance calculations showed that the heat transfer to the plasma-forming gas decreases with increase in arc current and the same was more significant at higher flow rates. Plasma jet velocity for different flow rates, input to the torch and nozzle dimensions was calculated from the gas enthalpy. It was found that the velocity increased with increase in the power input to the torch and gas flow rate and decreased with increase in nozzle length and diameter. The current voltage characteristics of the torch operating with argon gas were studied for different gas flow rates. The Nottingham coefficients were calculated using least square method.

Specification for procurement of water-level sensing instrumentation, specification number HIF-I-1

USGS Publications Warehouse

Rapp, D.H.

1982-01-01

This specification is to communicate to instrument manufacturers the U.S. Geological Survey 's requirements. It covers systems for sensing the elevation of the water surface on open channels, rivers, lakes, reservoirs, storm-sewer pipes, and observation wells at Survey data-collection sites. The signal output (mechanical or electrical) must meet the signal input requirements of analog to digital and digital input recorders in use by the Survey. A classification of stage-sensing systems by common characteristics is used to aid Survey people making system selections. These characteristics are (1) system type (contact or noncontact), (2) sensor type and sensing distance, (3) accuracy, (4) range, (5) power requirements, (6) system size and weight, and (7) data output signal. Acceptable system requirements cover system configurations, signal outputs, materials, operation manuals, detailed environmental conditions, calibration procedures, system accuracy, power requirements, installation limitations, maintainability, safety, and workmanship. An outline of the qualification test procedures and failure criteria are also given. The Hydrologic Instrumentation Facility at NSTL Station, Mississippi will test available systems to determine if they meet the specification in this report for inclusion in the Survey 's 'Qualified Products List'. This list will be used for future procurement of water-level sensing systems by the Survey. (USGS)

The 30-cm ion thruster power processor

NASA Technical Reports Server (NTRS)

Herron, B. G.; Hopper, D. J.

1978-01-01

A power processor unit for powering and controlling the 30 cm Mercury Electron-Bombardment Ion Thruster was designed, fabricated, and tested. The unit uses a unique and highly efficient transistor bridge inverter power stage in its implementation. The system operated from a 200 to 400 V dc input power bus, provides 12 independently controllable and closely regulated dc power outputs, and has an overall power conditioning capacity of 3.5 kW. Protective circuitry was incorporated as an integral part of the design to assure failure-free operation during transient and steady-state load faults. The implemented unit demonstrated an electrical efficiency between 91.5 and 91.9 at its nominal rated load over the 200 to 400 V dc input bus range.

Two-electrode non-differential biopotential amplifier.

PubMed

Dobrev, D

2002-09-01

A circuit is proposed for a non-differential two-electrode biopotential amplifier, with a current source and a transimpedance amplifier as a potential equaliser for its inputs, fully emulating a differential amplifier. The principle of operation is that the current in the input of the transimpedance amplifier is sensed and made to flow with the same value in the other input. The circuit has a simple structure and uses a small number of components. The current source maintains balanced common-mode interference currents, thus ensuring high signal input impedance. In addition, these currents can be tolerated up to more than 10 microA per input, at a supply voltage of +/- 5 V. A two-electrode differential amplifier with 2 x 10 Mohm input resistances to the reference point allows less than 0.5 microA per input. The circuit can be useful in cases of biosignal acquisition by portable instruments, using low supply voltages, from subjects in areas of high electromagnetic fields. Examples include biosignal recordings in electric power stations and electrically powered locomotives, where traditionally designed input amplifier stages can be saturated.

Advanced medium-voltage bidirectional dc-dc conversion systems for future electric energy delivery and management systems

NASA Astrophysics Data System (ADS)

Fan, Haifeng

2011-12-01

The distributed renewable energy generation and utilization are constantly growing, and are expected to be integrated with the conventional grid. The growing pressure for innovative solutions will demand power electronics to take an even larger role in future electric energy delivery and management systems, since power electronics are required for the conversion and control of electric energy by most dispersed generation systems Furthermore, power electronics systems can provide additional intelligent energy management, grid stability and power quality capabilities. Medium-voltage isolated dc-dc converter will become one of the key interfaces for grid components with moderate power ratings. To address the demand of medium voltage (MV) and high power capability for future electric energy delivery and management systems, the power electronics community and industry have been reacting in two different ways: developing semiconductor technology or directly connecting devices in series/parallel to reach higher nominal voltages and currents while maintaining conventional converter topologies; and by developing new converter topologies with traditional semiconductor technology, known as multilevel converters or modular converters. The modular approach uses the well-known, mature, and cheaper power semiconductor devices by adopting new converter topologies. The main advantages of the modular approach include: significant improvement in reliability by introducing desired level of redundancy; standardization of components leading to reduction in manufacturing cost and time; power systems can be easily reconfigured to support varying input-output specifications; and possibly higher efficiency and power density of the overall system. Input-series output-parallel (ISOP) modular configuration is a good choice to realize MV to low voltage (LV) conversion for utility application. However, challenges still remain. First of all, for the high-frequency MV utility application, the low switching loss and conduction loss are must-haves for high efficiency, while bidirectional power flow capability is a must for power management requirement. To address the demand, the phase-shift dual-halfbridge (DHB) is proposed as the constituent module of ISOP configuration for MV application. The proposed ISOP DHB converter employs zero-voltage-switching (ZVS) technique combined with LV MOSFETs to achieve low switching and conduction losses under high frequency operation, and therefore high efficiency and high power density, and bidirectional power flow as well. Secondly, a large load range of high efficiency is desired rather than only a specific load point due to the continuous operation and large load variation range of utility application, which is of high importance because of the rising energy cost. This work proposes a novel DHB converter with an adaptive commutation inductor. By utilizing an adaptive inductor as the main energy transfer element, the output power can be controlled by not only the phase shift but also the commutation inductance, which allows the circulating energy to be optimized for different load conditions to maintain ZVS under light load conditions and minimize additional conduction losses under heavy load conditions as well. As a result, the efficiency at both light and heavy load can be significantly improved compared with the conventional DHB converter, and therefore extended high-efficiency range can be achieved. In addition, current stress of switch devices can be reduced. The theoretical analysis is presented and validated by the experimental results on a 50 kHz, 1 kW dc-dc converter module. Thirdly, input-voltage sharing and output-current sharing are critical to assure the advantages of the ISOP modular configuration. To solve this issue, an identically distributed control scheme is proposed in this work. The proposed control scheme, using only one distributed voltage loop to realize both input-voltage and output-current sharing, provides plug-and-play capability, possible high-level fault tolerance, and easy implementation. Another unique advantage of the proposed ISOP DHB converter is the power rating can be easily extended further by directly connecting multiple ISOP DHB converters in input-parallel-outparallel (IPOP) while no additional control is needed. The proposed control scheme is elaborated using the large-signal average model. Further, the stability of the control schemes is analyzed in terms of the constituent modules' topology as well as the configuration, and then an important fact that the stability of control scheme depends on not only the configuration but also the constituent module topology is first revealed in this work. Finally, the simulation and experimental results of an ISOP DHB converter consisting of three modules are presented to verify the proposed control scheme and the high frequency high efficiency operation.

Power flow as a complement to statistical energy analysis and finite element analysis

NASA Technical Reports Server (NTRS)

Cuschieri, J. M.

1987-01-01

Present methods of analysis of the structural response and the structure-borne transmission of vibrational energy use either finite element (FE) techniques or statistical energy analysis (SEA) methods. The FE methods are a very useful tool at low frequencies where the number of resonances involved in the analysis is rather small. On the other hand SEA methods can predict with acceptable accuracy the response and energy transmission between coupled structures at relatively high frequencies where the structural modal density is high and a statistical approach is the appropriate solution. In the mid-frequency range, a relatively large number of resonances exist which make finite element method too costly. On the other hand SEA methods can only predict an average level form. In this mid-frequency range a possible alternative is to use power flow techniques, where the input and flow of vibrational energy to excited and coupled structural components can be expressed in terms of input and transfer mobilities. This power flow technique can be extended from low to high frequencies and this can be integrated with established FE models at low frequencies and SEA models at high frequencies to form a verification of the method. This method of structural analysis using power flo and mobility methods, and its integration with SEA and FE analysis is applied to the case of two thin beams joined together at right angles.

Electron density and gas density measurements in a millimeter-wave discharge

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

Schaub, S. C., E-mail: sschaub@mit.edu; Hummelt, J. S.; Guss, W. C.

2016-08-15

Electron density and neutral gas density have been measured in a non-equilibrium air breakdown plasma using optical emission spectroscopy and two-dimensional laser interferometry, respectively. A plasma was created with a focused high frequency microwave beam in air. Experiments were run with 110 GHz and 124.5 GHz microwaves at powers up to 1.2 MW. Microwave pulses were 3 μs long at 110 GHz and 2.2 μs long at 124.5 GHz. Electron density was measured over a pressure range of 25 to 700 Torr as the input microwave power was varied. Electron density was found to be close to the critical density, where the collisional plasma frequency is equal tomore » the microwave frequency, over the pressure range studied and to vary weakly with input power. Neutral gas density was measured over a pressure range from 150 to 750 Torr at power levels high above the threshold for initiating breakdown. The two-dimensional structure of the neutral gas density was resolved. Intense, localized heating was found to occur hundreds of nanoseconds after visible plasma formed. This heating led to neutral gas density reductions of greater than 80% where peak plasma densities occurred. Spatial structure and temporal dynamics of gas heating at atmospheric pressure were found to agree well with published numerical simulations.« less

Phase Difference between Model Cortical Areas Determines Level of Information Transfer

PubMed Central

ter Wal, Marije; Tiesinga, Paul H.

2017-01-01

Communication between cortical sites is mediated by long-range synaptic connections. However, these connections are relatively static, while everyday cognitive tasks demand a fast and flexible routing of information in the brain. Synchronization of activity between distant cortical sites has been proposed as the mechanism underlying such a dynamic communication structure. Here, we study how oscillatory activity affects the excitability and input-output relation of local cortical circuits and how it alters the transmission of information between cortical circuits. To this end, we develop model circuits showing fast oscillations by the PING mechanism, of which the oscillatory characteristics can be altered. We identify conditions for synchronization between two brain circuits and show that the level of intercircuit coherence and the phase difference is set by the frequency difference between the intrinsic oscillations. We show that the susceptibility of the circuits to inputs, i.e., the degree of change in circuit output following input pulses, is not uniform throughout the oscillation period and that both firing rate, frequency and power are differentially modulated by inputs arriving at different phases. As a result, an appropriate phase difference between the circuits is critical for the susceptibility windows of the circuits in the network to align and for information to be efficiently transferred. We demonstrate that changes in synchrony and phase difference can be used to set up or abolish information transfer in a network of cortical circuits. PMID:28232796

Mean field model of acetylcholine mediated dynamics in the cerebral cortex.

PubMed

Clearwater, J M; Rennie, C J; Robinson, P A

2007-12-01

A recent continuum model of the large scale electrical activity of the cerebral cortex is generalized to include cholinergic modulation. In this model, dynamic modulation of synaptic strength acts over the time scales of nicotinic and muscarinic receptor action. The cortical model is analyzed to determine the effect of acetylcholine (ACh) on its steady states, linear stability, spectrum, and temporal responses to changes in subcortical input. ACh increases the firing rate in steady states of the system. Changing ACh concentration does not introduce oscillatory behavior into the system, but increases the overall spectral power. Model responses to pulses in subcortical input are affected by the tonic level of ACh concentration, with higher levels of ACh increasing the magnitude firing rate response of excitatory cortical neurons to pulses of subcortical input. Numerical simulations are used to explore the temporal dynamics of the model in response to changes in ACh concentration. Evidence is seen of a transition from a state in which intracortical inputs are emphasized to a state where thalamic afferents have enhanced influence. Perturbations in ACh concentration cause changes in the firing rate of cortical neurons, with rapid responses due to fast acting facilitatory effects of nicotinic receptors on subcortical afferents, and slower responses due to muscarinic suppression of intracortical connections. Together, these numerical simulations demonstrate that the actions of ACh could be a significant factor modulating early components of evoked response potentials.

Catecholamine and second messenger influences on prefrontal cortical networks of "representational knowledge": a rational bridge between genetics and the symptoms of mental illness.

PubMed

Arnsten, Amy F T

2007-09-01

Both dopamine (DA) and norepinephrine (NE) have powerful, inverted U influences on prefrontal cortical (PFC) cognitive function. Optimal NE levels engage alpha2A-adrenoceptors and increase "signals" via inhibition of cAMP-HCN (cAMP-hyperpolarization-activated cyclic nucleotide-gated cation channel) signaling near preferred inputs, whereas optimal levels of DA D1 receptor stimulation decrease "noise" by increasing cAMP signaling near nonpreferred inputs. Excessive levels of catecholamine release during stress impair working memory 1) by very high levels of cAMP-HCN signaling diminishing preferred as well as nonpreferred inputs and 2) by high levels of NE engaging alpha1 stimulation of phosphotidyl inositol (PI) signaling that suppresses cell firing. Common mental illnesses are associated with extracellular changes in these pathways: Attention Deficit Hyperactivity Disorder is linked to genetic changes that reduce catecholamine transmission to suboptimal levels and is treated with agents that increase catecholamine transmission, whereas Post-Traumatic Stress Disorder (PTSD) is associated with amplified noradrenergic transmission that impairs PFC but strengthens amygdala function. PTSD is now treated with agents that block alpha1 or beta adrenoceptors. In contrast, the more severe mental illnesses, schizophrenia and bipolar disorder, are associated with genetic changes in molecules regulating intracellular signaling pathways activated by stress. Specifically, DISC1 inhibits cAMP signaling whereas regulator of G-protein signaling 4 inhibits PI signaling. Loss of function in these genes may render patients vulnerable to profound stress-induced PFC dysfunction including symptoms of thought disorder.

The effect of cutting conditions on power inputs when machining

NASA Astrophysics Data System (ADS)

Petrushin, S. I.; Gruby, S. V.; Nosirsoda, Sh C.

2016-08-01

Any technological process involving modification of material properties or product form necessitates consumption of a certain power amount. When developing new technologies one should take into account the benefits of their implementation vs. arising power inputs. It is revealed that procedures of edge cutting machining are the most energy-efficient amongst the present day forming procedures such as physical and technical methods including electrochemical, electroerosion, ultrasound, and laser processing, rapid prototyping technologies etc, such as physical and technical methods including electrochemical, electroerosion, ultrasound, and laser processing, rapid prototyping technologies etc. An expanded formula for calculation of power inputs is deduced, which takes into consideration the mode of cutting together with the tip radius, the form of the replaceable multifaceted insert and its wear. Having taken as an example cutting of graphite iron by the assembled cutting tools with replaceable multifaceted inserts the authors point at better power efficiency of high feeding cutting in comparison with high-speed cutting.

Solar Energetic Proton Nowcast for Low Earth Orbits

NASA Astrophysics Data System (ADS)

Winter, L. M.; Quinn, R. A.

2013-12-01

Solar energetic proton flux levels above > 10 pfu can damage spacecraft and pose a hazard to astronauts as well as passengers and crew on polar commercial flights. While the GOES satellites provide real-time data of SEP levels in geosynchronous orbit, it is also important to determine the risk to objects in lower altitude orbits. To assess this risk in real-time, we created a web-based nowcast of SEP flux. The tool determines the current solar energetic proton flux level given input position (latitude, longitude, and altitude) and energy of the protons (e.g., > 10 MeV). The effective cutoff energy is calculated for the location and current geomagnetic storm level (i.e., the Kp value from SWPC) using the Shea & Smart (e.g., Smart et al. 1999abc, 2000) geomagnetic cutoff model, which uses a trajectory tracing technique through the Tsyganenko magnetospheric model for the geomagnetic field. With the cutoff energy and GOES proton flux measurements, a map of the current predicted proton flux level at the input energy is displayed along with the calculated integral spectrum for the input position. This operational tool is a powerful new diagnostic for assessing the risk to spacecraft from current solar proton levels, with easy to read color-coded maps generated for all GOES integral proton flux energies and a range of altitudes (1000 - 35000 km). The figures show example maps over a ';'quiet'' (03-26-13) and active (10-30-03) time, with high proton levels easily distinguishable at or above the NOAA warning level (yellow-orange-red). The tool also displays the current GOES integral spectrum and fit, and the estimated spectrum at a user-defined location and altitude.

Unity Power Factor Operated PFC Converter Based Power Supply for Computers

NASA Astrophysics Data System (ADS)

Singh, Shikha; Singh, Bhim; Bhuvaneswari, G.; Bist, Vashist

2017-11-01

Power Supplies (PSs) employed in personal computers pollute the single phase ac mains by drawing distorted current at a substandard Power Factor (PF). The harmonic distortion of the supply current in these personal computers are observed 75% to 90% with the Crest Factor (CF) being very high which escalates losses in the distribution system. To find a tangible solution to these issues, a non-isolated PFC converter is employed at the input of isolated converter that is capable of improving the input power quality apart from regulating the dc voltage at its output. This is given to the isolated stage that yields completely isolated and stiffly regulated multiple output voltages which is the prime requirement of computer PS. The operation of the proposed PS is evaluated under various operating conditions and the results show improved performance depicting nearly unity PF and low input current harmonics. The prototype of this PS is developed in laboratory environment and test results are recorded which corroborate the power quality improvement observed in simulation results under various operating conditions.

Energy Survey of Machine Tools: Separating Power Information of the Main Transmission System During Machining Process

NASA Astrophysics Data System (ADS)

Liu, Shuang; Liu, Fei; Hu, Shaohua; Yin, Zhenbiao

The major power information of the main transmission system in machine tools (MTSMT) during machining process includes effective output power (i.e. cutting power), input power and power loss from the mechanical transmission system, and the main motor power loss. These information are easy to obtain in the lab but difficult to evaluate in a manufacturing process. To solve this problem, a separation method is proposed here to extract the MTSMT power information during machining process. In this method, the energy flow and the mathematical models of major power information of MTSMT during the machining process are set up first. Based on the mathematical models and the basic data tables obtained from experiments, the above mentioned power information during machining process can be separated just by measuring the real time total input power of the spindle motor. The operation program of this method is also given.

A Power Conditioning Stage Based on Analog-Circuit MPPT Control and a Superbuck Converter for Thermoelectric Generators in Spacecraft Power Systems

NASA Astrophysics Data System (ADS)

Sun, Kai; Wu, Hongfei; Cai, Yan; Xing, Yan

2014-06-01

A thermoelectric generator (TEG) is a very important kind of power supply for spacecraft, especially for deep-space missions, due to its long lifetime and high reliability. To develop a practical TEG power supply for spacecraft, a power conditioning stage is indispensable, being employed to convert the varying output voltage of the TEG modules to a definite voltage for feeding batteries or loads. To enhance the system reliability, a power conditioning stage based on analog-circuit maximum-power-point tracking (MPPT) control and a superbuck converter is proposed in this paper. The input of this power conditioning stage is connected to the output of the TEG modules, and the output of this stage is connected to the battery and loads. The superbuck converter is employed as the main circuit, featuring low input current ripples and high conversion efficiency. Since for spacecraft power systems reliable operation is the key target for control circuits, a reset-set flip-flop-based analog circuit is used as the basic control circuit to implement MPPT, being much simpler than digital control circuits and offering higher reliability. Experiments have verified the feasibility and effectiveness of the proposed power conditioning stage. The results show the advantages of the proposed stage, such as maximum utilization of TEG power, small input ripples, and good stability.

Power MOSFET Linearizer of a High-Voltage Power Amplifier for High-Frequency Pulse-Echo Instrumentation.

PubMed

Choi, Hojong; Woo, Park Chul; Yeom, Jung-Yeol; Yoon, Changhan

2017-04-04

A power MOSFET linearizer is proposed for a high-voltage power amplifier (HVPA) used in high-frequency pulse-echo instrumentation. The power MOSFET linearizer is composed of a DC bias-controlled series power MOSFET shunt with parallel inductors and capacitors. The proposed scheme is designed to improve the gain deviation characteristics of the HVPA at higher input powers. By controlling the MOSFET bias voltage in the linearizer, the gain reduction into the HVPA was compensated, thereby reducing the echo harmonic distortion components generated by the ultrasonic transducers. In order to verify the performance improvement of the HVPA implementing the power MOSFET linearizer, we measured and found that the gain deviation of the power MOSFET linearizer integrated with HVPA under 10 V DC bias voltage was reduced (-1.8 and -0.96 dB, respectively) compared to that of the HVPA without the power MOSFET linearizer (-2.95 and -3.0 dB, respectively) when 70 and 80 MHz, three-cycle, and 26 dB m input pulse waveforms are applied, respectively. The input 1-dB compression point (an index of linearity) of the HVPA with power MOSFET linearizer (24.17 and 26.19 dB m at 70 and 80 MHz, respectively) at 10 V DC bias voltage was increased compared to that of HVPA without the power MOSFET linearizer (22.03 and 22.13 dB m at 70 and 80 MHz, respectively). To further verify the reduction of the echo harmonic distortion components generated by the ultrasonic transducers, the pulse-echo responses in the pulse-echo instrumentation were compared when using HVPA with and without the power MOSFET linearizer. When three-cycle 26 dB m input power was applied, the second, third, fourth, and fifth harmonic distortion components of a 75 MHz transducer driven by the HVPA with power MOSFET linearizer (-48.34, -44.21, -48.34, and -46.56 dB, respectively) were lower than that of the HVPA without the power MOSFET linearizer (-45.61, -41.57, -45.01, and -45.51 dB, respectively). When five-cycle 20 dB m input power was applied, the second, third, fourth, and fifth harmonic distortions of the HVPA with the power MOSFET linearizer (-41.54, -41.80, -48.86, and -46.27 dB, respectively) were also lower than that of the HVPA without the power MOSFET linearizer (-25.85, -43.56, -49.04, and -49.24 dB, respectively). Therefore, we conclude that the power MOSFET linearizer could reduce gain deviation of the HVPA, thus reducing the echo signal harmonic distortions generated by the high-frequency ultrasonic transducers in pulse-echo instrumentation.

Power MOSFET Linearizer of a High-Voltage Power Amplifier for High-Frequency Pulse-Echo Instrumentation

PubMed Central

Choi, Hojong; Woo, Park Chul; Yeom, Jung-Yeol; Yoon, Changhan

2017-01-01

A power MOSFET linearizer is proposed for a high-voltage power amplifier (HVPA) used in high-frequency pulse-echo instrumentation. The power MOSFET linearizer is composed of a DC bias-controlled series power MOSFET shunt with parallel inductors and capacitors. The proposed scheme is designed to improve the gain deviation characteristics of the HVPA at higher input powers. By controlling the MOSFET bias voltage in the linearizer, the gain reduction into the HVPA was compensated, thereby reducing the echo harmonic distortion components generated by the ultrasonic transducers. In order to verify the performance improvement of the HVPA implementing the power MOSFET linearizer, we measured and found that the gain deviation of the power MOSFET linearizer integrated with HVPA under 10 V DC bias voltage was reduced (−1.8 and −0.96 dB, respectively) compared to that of the HVPA without the power MOSFET linearizer (−2.95 and −3.0 dB, respectively) when 70 and 80 MHz, three-cycle, and 26 dBm input pulse waveforms are applied, respectively. The input 1-dB compression point (an index of linearity) of the HVPA with power MOSFET linearizer (24.17 and 26.19 dBm at 70 and 80 MHz, respectively) at 10 V DC bias voltage was increased compared to that of HVPA without the power MOSFET linearizer (22.03 and 22.13 dBm at 70 and 80 MHz, respectively). To further verify the reduction of the echo harmonic distortion components generated by the ultrasonic transducers, the pulse-echo responses in the pulse-echo instrumentation were compared when using HVPA with and without the power MOSFET linearizer. When three-cycle 26 dBm input power was applied, the second, third, fourth, and fifth harmonic distortion components of a 75 MHz transducer driven by the HVPA with power MOSFET linearizer (−48.34, −44.21, −48.34, and −46.56 dB, respectively) were lower than that of the HVPA without the power MOSFET linearizer (−45.61, −41.57, −45.01, and −45.51 dB, respectively). When five-cycle 20 dBm input power was applied, the second, third, fourth, and fifth harmonic distortions of the HVPA with the power MOSFET linearizer (−41.54, −41.80, −48.86, and −46.27 dB, respectively) were also lower than that of the HVPA without the power MOSFET linearizer (−25.85, −43.56, −49.04, and −49.24 dB, respectively). Therefore, we conclude that the power MOSFET linearizer could reduce gain deviation of the HVPA, thus reducing the echo signal harmonic distortions generated by the high-frequency ultrasonic transducers in pulse-echo instrumentation. PMID:28375165

Impact of CO2 laser and stannous fluoride on primary tooth erosion.

PubMed

Rocha, Cristiane Tomaz; Turssi, Cecilia Pedroso; Rodrigues-Júnior, Antonio Luiz; Corona, Silmara Aparecida Milori

2016-04-01

This study evaluated in vitro the effect of input power of CO2 laser, either associated or not to stannous fluoride (SnF2) gel, for the control of intrinsic erosion in primary teeth. One hundred four enamel slabs (3 × 3 × 2 mm) from human primary molars were flattened and polished. Adhesive tapes were placed on their surface leaving a window of 3 × 1 mm. Slabs were then cycled four times in 0.01 M hydrochloric acid (pH 2, 2 min) and in artificial saliva (2 h) for creation of erosive lesions. Specimens were randomly assigned into eight groups (n = 13) according to fluoride application [absent (control) or 0.4% stannous fluoride gel (SnF2)] and input power of CO2 laser [unlased (control), 0.5, 1.0 or 1.5 W]. The CO2 laser irradiation was performed in an ultra-pulse mode (100 μs of pulse duration), 4-mm working distance, for 10 s. Specimens were then submitted to further erosive episodes for 5 days and evaluated for enamel relative permeability. Fluoride did not show any protective effect for any of the laser-treated groups or control (p = 0.185). However, a significant effect was detected for input power of CO2 laser (p = 0.037). Tukey's test showed that there was a significant statistically difference between specimens irradiated with 0.5 and 1.5 W (p = 0.028). The input power of 0.5 W showed lower permeability. Variation of input power CO2 laser can influence enamel permeability, at the power of 1.5 W which promoted greater permeability.

Two new families of high-gain dc-dc power electronic converters for dc-microgrids

NASA Astrophysics Data System (ADS)

Prabhala, Venkata Anand Kishore

Distributing the electric power in dc form is an appealing solution in many applications such as telecommunications, data centers, commercial buildings, and microgrids. A high gain dc-dc power electronic converter can be used to individually link low-voltage elements such as solar panels, fuel cells, and batteries to the dc voltage bus which is usually 400 volts. This way, it is not required to put such elements in a series string to build up their voltages. Consequently, each element can function at it optimal operating point regardless of the other elements in the system. In this dissertation, first a comparative study of dc microgrid architectures and their advantages over their ac counterparts is presented. Voltage level selection of dc distribution systems is discussed from the cost, reliability, efficiency, and safety standpoints. Next, a new family of non-isolated high-voltage-gain dc-dc power electronic converters with unidirectional power flow is introduced. This family of converters benefits from a low voltage stress across its switches. The proposed topologies are versatile as they can be utilized as single-input or double-input power converters. In either case, they draw continuous currents from their sources. Lastly, a bidirectional high-voltage-gain dc-dc power electronic converter is proposed. This converter is comprised of a bidirectional boost converter which feeds a switched-capacitor architecture. The switched-capacitor stage suggested here has several advantages over the existing approaches. For example, it benefits from a higher voltage gain while it uses less number of capacitors. The proposed converters are highly efficient and modular. The operating modes, dc voltage gain, and design procedure for each converter are discussed in details. Hardware prototypes have been developed in the lab. The results obtained from the hardware agree with those of the simulation models.

Measurement of ozone production scaling in a helium plasma jet with oxygen admixture

NASA Astrophysics Data System (ADS)

Sands, Brian; Ganguly, Biswa

2012-10-01

Capillary dielectric barrier plasma jet devices that generate confined streamer-like discharges along a rare gas flow can produce significant quantities of reactive oxygen species with average input powers ranging from 100 mW to >1 W. We have measured spatially-resolved ozone production in a He plasma jet with O2 admixture concentrations up to 5% using absorption spectroscopy of the O3 Hartley band system. A 20-ns risetime, 10-13 kV positive unipolar voltage pulse train was used to power the discharge, with pulse repetition rates varied from 1-20 kHz. The discharge was operated in a transient glow mode to scale the input power by adjusting the gap width between the anode and downstream cathodic plane. Peak ozone number densities in the range of 10^16 - 10^17 cm-3 were measured. At a given voltage, the density of ozone increased monotonically up to 3% O2 admixture (6 mm gap) as the peak discharge current decreased by an order of magnitude. Ozone production increased with distance from the capillary, consistent with observations by other groups. Atomic oxygen production inferred from O-atom 777 nm emission intensity did not scale with ozone as the input power was increased. The spatial distribution of ozone and scaling with input power will be presented.

RF digital-to-analog converter

DOEpatents

Conway, P.H.; Yu, D.U.L.

1995-02-28

A digital-to-analog converter is disclosed for producing an RF output signal proportional to a digital input word of N bits from an RF reference input, N being an integer greater or equal to 2. The converter comprises a plurality of power splitters, power combiners and a plurality of mixers or RF switches connected in a predetermined configuration. 18 figs.

Quantum dot SOA input power dynamic range improvement for differential-phase encoded signals.

PubMed

Vallaitis, T; Bonk, R; Guetlein, J; Hillerkuss, D; Li, J; Brenot, R; Lelarge, F; Duan, G H; Freude, W; Leuthold, J

2010-03-15

Experimentally we find a 10 dB input power dynamic range advantage for amplification of phase encoded signals with quantum dot SOA as compared to low-confinement bulk SOA. An analysis of amplitude and phase effects shows that this improvement can be attributed to the lower alpha-factor found in QD SOA.

High-Power, High-Efficiency Ka-Band Space Traveling-Wave Tube

NASA Technical Reports Server (NTRS)

Krawczyk, Richard; Wilson, Jeffrey; Simons, Rainee; Williams, Wallace; Bhasin, Kul; Robbins, Neal; Dibb, Daniel; Menninger, William; Zhai, Xiaoling; Benton, Robert;

Electric vehicle drive train with contactor protection

DOEpatents

Konrad, Charles E.; Benson, Ralph A.

1994-01-01

A drive train for an electric vehicle includes a traction battery, a power drive circuit, a main contactor for connecting and disconnecting the traction battery and the power drive circuit, a voltage detector across contacts of the main contactor, and a controller for controlling the main contactor to prevent movement of its contacts to the closed position when the voltage across the contacts exceeds a predetermined threshold, to thereby protect the contacts of the contactor. The power drive circuit includes an electric traction motor and a DC-to-AC inverter with a capacitive input filter. The controller also inhibits the power drive circuit from driving the motor and thereby discharging the input capacitor if the contacts are inadvertently opened during motoring. A precharging contactor is controlled to charge the input filter capacitor prior to closing the main contactor to further protect the contacts of the main contactor.

Electric vehicle drive train with contactor protection

DOEpatents

Konrad, C.E.; Benson, R.A.

1994-11-29

A drive train for an electric vehicle includes a traction battery, a power drive circuit, a main contactor for connecting and disconnecting the traction battery and the power drive circuit, a voltage detector across contacts of the main contactor, and a controller for controlling the main contactor to prevent movement of its contacts to the closed position when the voltage across the contacts exceeds a predetermined threshold, to thereby protect the contacts of the contactor. The power drive circuit includes an electric traction motor and a DC-to-AC inverter with a capacitive input filter. The controller also inhibits the power drive circuit from driving the motor and thereby discharging the input capacitor if the contacts are inadvertently opened during motoring. A precharging contactor is controlled to charge the input filter capacitor prior to closing the main contactor to further protect the contacts of the main contactor. 3 figures.

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.

Multiple high voltage output DC-to-DC power converter

NASA Technical Reports Server (NTRS)

Cronin, Donald L. (Inventor); Farber, Bertrand F. (Inventor); Gehm, Hartmut K. (Inventor); Goldin, Daniel S. (Inventor)

1977-01-01

Disclosed is a multiple output DC-to-DC converter. The DC input power is filtered and passed through a chopper preregulator. The chopper output is then passed through a current source inverter controlled by a squarewave generator. The resultant AC is passed through the primary winding of a transformer, with high voltages induced in a plurality of secondary windings. The high voltage secondary outputs are each solid-state rectified for passage to individual output loads. Multiple feedback loops control the operation of the chopper preregulator, one being responsive to the current through the primary winding and another responsive to the DC voltage level at a selected output.

Characteristic of a Digital Correlation Radiometer Back End with Finite Wordlength

NASA Technical Reports Server (NTRS)

Biswas, Sayak K.; Hyde, David W.; James, Mark W.; Cecil, Daniel J.

2017-01-01

The performance characteristic of a digital correlation radiometer signal processing back end (DBE) is analyzed using a simulator. The particular design studied here corresponds to the airborne Hurricane Imaging radiometer which was jointly developed by the NASA Marshall Space Flight Center, University of Michigan, University of Central Florida and NOAA. Laboratory and flight test data is found to be in accord with the simulation results. Overall design seems to be optimum for the typical input signal dynamic range. It was found that the performance of the digital kurtosis could be improved by lowering the DBE input power level. An unusual scaling between digital correlation channels observed in the instrument data is confirmed to be a DBE characteristic.

On the physical basis of succussion.

PubMed

Torres, J L

2002-10-01

It is argued that succussion drives the homeopathic tincture undergoing potentisation to a turbulent regime, where vortices continually form and disappear, ranging in size from the linear extent of the container to a minimum scale determined by viscosity and the rate of energy dissipation. Input mechanical energy cascades down this population of eddies and becomes available at the microscopic level to perform work (chemical, electrical, etc). A structure generated in the tincture would be rupted by vortices smaller than it, and this sets definite limits on the strength of succussion, so the power input leads to larger vortices than the structures one is trying to create and preserve through potentisation. An experimental procedure to test this proposal is suggested, based on Rayleigh scattering.

Low-Power Ion Thruster Development Status

NASA Technical Reports Server (NTRS)

Patterson, Michael J.

1999-01-01

An effort is on-going to examine scaling relationships and design criteria for ion propulsion systems, and to address the need for a light weight, low power, high specific impulse propulsion option for small spacecraft. An element of this activity is the development of a low-power (sub-0.5 kW) ion thruster. This development effort has led to the fabrication and preliminary performance assessment of an 8 cm prototype xenon ion thruster operating over an input power envelope of 0.1-0.3 kW. Efficiencies for the thruster vary from 0.31 at 1750 seconds specific impulse at 0.1 kW, to about 0.48 at 2700 seconds specific impulse and 0.3 kW input power. Discharge losses for the thruster over this power range varied from about 320-380 W/A down to about 220-250 W/A. Ion optics performance compare favorably to that obtained with 30 cm ion optics, when scaled for the difference in beam area. The neutralizer, fabricated using 3 mm hollow cathode technology, operated at keeper currents of about 0.2-0.3 A, at a xenon flow rate of about 0.06 mg/s, over the 0.1-0.3 kW thruster input power envelope.

Development and Testing of an Ultra Low Power System-On-Chip (SOC) Platform for Marine Mammal Tags and Passive Acoustic Signal Processing

DTIC Science & Technology

2014-09-30

current (3-5mA). The system can harvest 16 power from a DC input source like a thermoelectric generator (TEG) or photovoltaic cell (PV). The boost...results from components to report. Designed for thermoelectric energy harvesting in 130nm CMOS, the boost converter reduces the achievable input...harvesting. The boost converter further incorporates maximum power point tracking for harvesting from both thermoelectric generators (TEGs) and solar

Computational Design of Materials: Planetary Entry to Electric Aircraft and Beyond

NASA Technical Reports Server (NTRS)

Thompson, Alexander; Lawson, John W.

2014-01-01

NASA's projects and missions push the bounds of what is possible. To support the agency's work, materials development must stay on the cutting edge in order to keep pace. Today, researchers at NASA Ames Research Center perform multiscale modeling to aid the development of new materials and provide insight into existing ones. Multiscale modeling enables researchers to determine micro- and macroscale properties by connecting computational methods ranging from the atomic level (density functional theory, molecular dynamics) to the macroscale (finite element method). The output of one level is passed on as input to the next level, creating a powerful predictive model.

Development and Testing of a High Level Axial Array Duct Sound Source for the NASA Flow Impedance Test Facility

NASA Technical Reports Server (NTRS)

Johnson, Marty E.; Fuller, Chris R.; Jones, Michael G. (Technical Monitor)

2000-01-01

In this report both a frequency domain method for creating high level harmonic excitation and a time domain inverse method for creating large pulses in a duct are developed. To create controllable, high level sound an axial array of six JBL-2485 compression drivers was used. The pressure downstream is considered as input voltages to the sources filtered by the natural dynamics of the sources and the duct. It is shown that this dynamic behavior can be compensated for by filtering the inputs such that both time delays and phase changes are taken into account. The methods developed maximize the sound output while (i) keeping within the power constraints of the sources and (ii) maintaining a suitable level of reproduction accuracy. Harmonic excitation pressure levels of over 155dB were created experimentally over a wide frequency range (1000-4000Hz). For pulse excitation there is a tradeoff between accuracy of reproduction and sound level achieved. However, the accurate reproduction of a pulse with a maximum pressure level over 6500Pa was achieved experimentally. It was also shown that the throat connecting the driver to the duct makes it difficult to inject sound just below the cut-on of each acoustic mode (pre cut-on loading effect).

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.

Flexible and multi-directional piezoelectric energy harvester for self-powered human motion sensor

NASA Astrophysics Data System (ADS)

Kim, Min-Ook; Pyo, Soonjae; Oh, Yongkeun; Kang, Yunsung; Cho, Kyung-Ho; Choi, Jungwook; Kim, Jongbaeg

2018-03-01

A flexible piezoelectric strain energy harvester that is responsive to multi-directional input forces produced by various human motions is proposed. The structure of the harvester, which includes a polydimethylsiloxane (PDMS) bump, facilitates the effective conversion of strain energy, produced by input forces applied in random directions, into electrical energy. The structural design of the PDMS bump and frame as well as the slits in the piezoelectric polyvinylidene fluoride (PVDF) film provide mechanical flexibility and enhance the strain induced in the PVDF film under input forces applied at various angles. The amount and direction of the strain induced in PVDF can be changed by the direction of the applied force; thus, the generated output power can be varied. The measured maximum output peak voltage is 1.75, 1.29, and 0.98 V when an input force of 4 N (2 Hz) is applied at angles of 0°, 45°, and 90°, and the corresponding maximum output power is 0.064, 0.026, and 0.02 μW, respectively. Moreover, the harvester stably generates output voltage over 1.4 × 104 cycles. Thus, the proposed harvester successfully identifies and converts strain energy produced by multi-directional input forces by various human motions into electrical energy. We demonstrate the potential utility of the proposed flexible energy harvester as a self-powered human motion sensor for wireless healthcare systems.

Quality factor concept in piezoceramic transformer performance description.

PubMed

Mezheritsky, Alex V

2006-02-01

A new general approach based on the quality factor concept to piezoceramic transformer (PT) performance description is proposed. The system's quality factor, material elastic anisotropy, and coupling factors of the input and output sections of an electrically excited and electrically loaded PT fully characterize its resonance and near-resonance behavior. The PT efficiency, transformation ratio, and input and output power were analytically analyzed and simulated as functions of the load and frequency for the simplest classical Langevin-type and Rosen-type PT designs. A new formulation of the electrical input impedance allows one to separate the power consumed by PT from the power transferred into the load. The system's PT quality factor takes into account losses in each PT "input-output-load" functional components. The loading process is changing PT input electrical impedance on the way that under loading the minimum series impedance is increasing and the maximum parallel impedance is decreasing coincidentally. The quality-factors ratio, between the states of fully loaded and nonloaded PT, is one of the best measures of PTs dynamic performance--practically, the lower the ratio is, the better PT efficiency. A simple and effective method for the loaded PT quality factor determination is proposed. As was found, a piezoceramic with low piezoelectric anisotropy is required to provide maximum PT efficiency and higher corresponding voltage gain. Limitations on the PT output voltage and power, caused by nonlinear effects in piezoceramics, were established.

On-Chip Power-Combining for High-Power Schottky Diode-Based Frequency Multipliers

NASA Technical Reports Server (NTRS)

Chattopadhyay, Goutam; Mehdi, Imran; Schlecht, Erich T.; Lee, Choonsup; Siles, Jose V.; Maestrini, Alain E.; Thomas, Bertrand; Jung, Cecile D.

2013-01-01

A 1.6-THz power-combined Schottky frequency tripler was designed to handle approximately 30 mW input power. The design of Schottky-based triplers at this frequency range is mainly constrained by the shrinkage of the waveguide dimensions with frequency and the minimum diode mesa sizes, which limits the maximum number of diodes that can be placed on the chip to no more than two. Hence, multiple-chip power-combined schemes become necessary to increase the power-handling capabilities of high-frequency multipliers. The design presented here overcomes difficulties by performing the power-combining directly on-chip. Four E-probes are located at a single input waveguide in order to equally pump four multiplying structures (featuring two diodes each). The produced output power is then recombined at the output using the same concept.

Optimal wide-area monitoring and nonlinear adaptive coordinating neurocontrol of a power system with wind power integration and multiple FACTS devices.

PubMed

Qiao, Wei; Venayagamoorthy, Ganesh K; Harley, Ronald G

2008-01-01

Wide-area coordinating control is becoming an important issue and a challenging problem in the power industry. This paper proposes a novel optimal wide-area coordinating neurocontrol (WACNC), based on wide-area measurements, for a power system with power system stabilizers, a large wind farm and multiple flexible ac transmission system (FACTS) devices. An optimal wide-area monitor (OWAM), which is a radial basis function neural network (RBFNN), is designed to identify the input-output dynamics of the nonlinear power system. Its parameters are optimized through particle swarm optimization (PSO). Based on the OWAM, the WACNC is then designed by using the dual heuristic programming (DHP) method and RBFNNs, while considering the effect of signal transmission delays. The WACNC operates at a global level to coordinate the actions of local power system controllers. Each local controller communicates with the WACNC, receives remote control signals from the WACNC to enhance its dynamic performance and therefore helps improve system-wide dynamic and transient performance. The proposed control is verified by simulation studies on a multimachine power system.

Effects of vibration and shock on the performance of gas-bearing space-power Brayton cycle turbomachinery. 2: Sinusoidal and random vibration

NASA Technical Reports Server (NTRS)

Tessarzik, J. M.; Chiang, T.; Badgley, R. H.

1973-01-01

The vibration response of a gas-bearing rotor-support system was analyzed experimentally documented for sinusoidal and random vibration environments. The NASA Brayton Rotating Unit (BRU), 36,000 rpm; 10 KWe turbogenerator; was subjected in the laboratory to sinusoidal and random vibrations to evaluate the capability of the BRU to (1) survive the vibration levels expected to be encountered during periods of nonoperation and (2) operate satisfactorily (that is, without detrimental bearing surface contacts) at the vibration levels expected during normal BRU operation. Response power spectral density was calculated for specified input random excitation, with particular emphasis upon the dynamic motions of the thrust bearing runner and stator. A three-mass model with nonlinear representation of the engine isolator mounts was used to calculate axial rotor-bearing shock response.

Microwave applicator for in-drum processing of radioactive waste slurry

DOEpatents

White, Terry L.

1994-01-01

A microwave applicator for processing of radioactive waste slurry uses a waveguide network which splits an input microwave of TE.sub.10 rectangular mode to TE.sub.01 circular mode. A cylindrical body has four openings, each receiving 1/4 of the power input. The waveguide network includes a plurality of splitters to effect the 1/4 divisions of power.

Fabrication of Scalable Indoor Light Energy Harvester and Study for Agricultural IoT Applications

NASA Astrophysics Data System (ADS)

Watanabe, M.; Nakamura, A.; Kunii, A.; Kusano, K.; Futagawa, M.

2015-12-01

A scalable indoor light energy harvester was fabricated by microelectromechanical system (MEMS) and printing hybrid technology and evaluated for agricultural IoT applications under different environmental input power density conditions, such as outdoor farming under the sun, greenhouse farming under scattered lighting, and a plant factory under LEDs. We fabricated and evaluated a dye- sensitized-type solar cell (DSC) as a low cost and “scalable” optical harvester device. We developed a transparent conductive oxide (TCO)-less process with a honeycomb metal mesh substrate fabricated by MEMS technology. In terms of the electrical and optical properties, we achieved scalable harvester output power by cell area sizing. Second, we evaluated the dependence of the input power scalable characteristics on the input light intensity, spectrum distribution, and light inlet direction angle, because harvested environmental input power is unstable. The TiO2 fabrication relied on nanoimprint technology, which was designed for optical optimization and fabrication, and we confirmed that the harvesters are robust to a variety of environments. Finally, we studied optical energy harvesting applications for agricultural IoT systems. These scalable indoor light harvesters could be used in many applications and situations in smart agriculture.

Digital Control Technologies for Modular DC-DC Converters

NASA Technical Reports Server (NTRS)

Button, Robert M.; Kascak, Peter E.; Lebron-Velilla, Ramon

2002-01-01

Recent trends in aerospace Power Management and Distribution (PMAD) systems focus on using commercial off-the-shelf (COTS) components as standard building blocks. This move to more modular designs has been driven by a desire to reduce costs and development times, but is also due to the impressive power density and efficiency numbers achieved by today's commercial DC-DC converters. However, the PMAD designer quickly learns of the hidden "costs" of using COTS converters. The most significant cost is the required addition of external input filters to meet strict electromagnetic interference (MIAMI) requirements for space systems. In fact, the high power density numbers achieved by the commercial manufacturers are greatly due to the lack of necessary input filters included in the COTS module. The NASA Glenn Research Center is currently pursuing a digital control technology that addresses this problem with modular DC-DC converters. This paper presents the digital control technologies that have been developed to greatly reduce the input filter requirements for paralleled, modular DC-DC converters. Initial test result show that the input filter's inductor size was reduced by 75 percent, and the capacitor size was reduced by 94 percent while maintaining the same power quality specifications.

Real power regulation for the utility power grid via responsive loads

DOEpatents

McIntyre, Timothy J [Knoxville, TN; Kirby, Brendan J [Knoxville, TN; Kisner, Roger A

2009-05-19

A system for dynamically managing an electrical power system that determines measures of performance and control criteria for the electric power system, collects at least one automatic generation control (AGC) input parameter to at least one AGC module and at least one automatic load control (ALC) input parameter to at least one ALC module, calculates AGC control signals and loads as resources (LAR) control signals in response to said measures of performance and control criteria, propagates AGC control signals to power generating units in response to control logic in AGC modules, and propagates LAR control signals to at least one LAR in response to control logic in ALC modules.

Quality engineering tools focused on high power LED driver design using boost power stages in switch mode

NASA Astrophysics Data System (ADS)

Ileana, Ioan; Risteiu, Mircea; Marc, Gheorghe

2016-12-01

This paper is a part of our research dedicated to high power LED lamps designing. The boost-up selected technology wants to meet driver producers' tendency in the frame of efficiency and disturbances constrains. In our work we used modeling and simulation tools for implementing scenarios of the driver work when some controlling functions are executed (output voltage/ current versus input voltage and fixed switching frequency, input and output electric power transfer versus switching frequency, transient inductor voltage analysis, and transient out capacitor analysis). Some electrical and thermal stress conditions are also analyzed. Based on these aspects, a high reliable power LED driver has been designed.

Contributions of tidal lung inflation to human R-R interval and arterial pressure fluctuations

NASA Technical Reports Server (NTRS)

Koh, J.; Brown, T. E.; Beightol, L. A.; Eckberg, D. L.

1998-01-01

We studied the effects of mechanical lung inflation on respiratory frequency R-R interval and arterial pressure fluctuations in nine healthy young adults undergoing elective orthopedic surgery. We conducted this research to define the contribution of pulmonary and thoracic stretch receptor input to respiratory sinus arrhythmia. We compared fast Fourier transform spectral power during three modes of ventilation: (1) spontaneous, frequency-controlled (0.25 Hz) breathing, (2) intermittent positive pressure ventilation (0.25 Hz, with a tidal volume of 8 ml/kg) and (3) high frequency jet ventilation (5.0 Hz, 2.5 kg/cm2), after sedation and vecuronium paralysis. Mean R-R intervals, arterial pressures and arterial blood gas levels were comparable during all three breathing conditions. Respiratory frequency systolic pressure spectral power was comparable during spontaneous breathing and conventional mechanical ventilation, but was significantly reduced during high frequency jet ventilation (P < 0.05). Respiratory frequency R-R interval spectral power (used as an index of respiratory sinus arrhythmia) declined dramatically with sedation and muscle paralysis (P < 0.05), but was greater during conventional mechanical, than high frequency jet ventilation (P < 0.05). These results suggest that although phasic inputs from pulmonary and thoracic stretch receptors make a statistically significant contribution to respiratory sinus arrhythmia, that contribution is small.

Power oscillator

DOEpatents

Gitsevich, Aleksandr

2001-01-01

An oscillator includes an amplifier having an input and an output, and an impedance transformation network connected between the input of the amplifier and the output of the amplifier, wherein the impedance transformation network is configured to provide suitable positive feedback from the output of the amplifier to the input of the amplifier to initiate and sustain an oscillating condition, and wherein the impedance transformation network is configured to protect the input of the amplifier from a destructive feedback signal. One example of the oscillator is a single active element device capable of providing over 70 watts of power at over 70% efficiency. Various control circuits may be employed to match the driving frequency of the oscillator to a plurality of tuning states of the lamp.

Meter circuit for tuning RF amplifiers

NASA Technical Reports Server (NTRS)

Longthorne, J. E.

1973-01-01

Circuit computes and indicates efficiency of RF amplifier as inputs and other parameters are varied. Voltage drop across internal resistance of ammeter is amplified by operational amplifier and applied to one multiplier input. Other input is obtained through two resistors from positive terminal of power supply.

Cloud-Based Orchestration of a Model-Based Power and Data Analysis Toolchain

NASA Technical Reports Server (NTRS)

Post, Ethan; Cole, Bjorn; Dinkel, Kevin; Kim, Hongman; Lee, Erich; Nairouz, Bassem

2016-01-01

The proposed Europa Mission concept contains many engineering and scientific instruments that consume varying amounts of power and produce varying amounts of data throughout the mission. System-level power and data usage must be well understood and analyzed to verify design requirements. Numerous cross-disciplinary tools and analysis models are used to simulate the system-level spacecraft power and data behavior. This paper addresses the problem of orchestrating a consistent set of models, tools, and data in a unified analysis toolchain when ownership is distributed among numerous domain experts. An analysis and simulation environment was developed as a way to manage the complexity of the power and data analysis toolchain and to reduce the simulation turnaround time. A system model data repository is used as the trusted store of high-level inputs and results while other remote servers are used for archival of larger data sets and for analysis tool execution. Simulation data passes through numerous domain-specific analysis tools and end-to-end simulation execution is enabled through a web-based tool. The use of a cloud-based service facilitates coordination among distributed developers and enables scalable computation and storage needs, and ensures a consistent execution environment. Configuration management is emphasized to maintain traceability between current and historical simulation runs and their corresponding versions of models, tools and data.

Wave-plate structures, power selective optical filter devices, and optical systems using same

DOEpatents

Koplow, Jeffrey P [San Ramon, CA

2012-07-03

In an embodiment, an optical filter device includes an input polarizer for selectively transmitting an input signal. The device includes a wave-plate structure positioned to receive the input signal, which includes first and second substantially zero-order, zero-wave plates arranged in series with and oriented at an angle relative to each other. The first and second zero-wave plates are configured to alter a polarization state of the input signal passing in a manner that depends on the power of the input signal. Each zero-wave plate includes an entry and exit wave plate each having a fast axis, with the fast axes oriented substantially perpendicular to each other. Each entry wave plate is oriented relative to a transmission axis of the input polarizer at a respective angle. An output polarizer is positioned to receive a signal output from the wave-plate structure and selectively transmits the signal based on the polarization state.

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.

NASA's Evolutionary Xenon Thruster (NEXT) Prototype Model 1R (PM1R) Ion Thruster and Propellant Management System Wear Test Results

NASA Technical Reports Server (NTRS)

VanNoord, Jonathan L.; Soulas, George C.; Sovey, James S.

2010-01-01

The results of the NEXT wear test are presented. This test was conducted with a 36-cm ion engine (designated PM1R) and an engineering model propellant management system. The thruster operated with beam extraction for a total of 1680 hr and processed 30.5 kg of xenon during the wear test, which included performance testing and some operation with an engineering model power processing unit. A total of 1312 hr was accumulated at full power, 277 hr at low power, and the remainder was at intermediate throttle levels. Overall ion engine performance, which includes thrust, thruster input power, specific impulse, and thrust efficiency, was steady with no indications of performance degradation. The propellant management system performed without incident during the wear test. The ion engine and propellant management system were also inspected following the test with no indication of anomalous hardware degradation from operation.

Intermediate photovoltaic system application experiment operational performance report. Volume 6: Beverly High School, Beverly, Mass.

NASA Astrophysics Data System (ADS)

1982-03-01

Performance data are given for the month of February, 1982 for a photovoltaic power supply at a Massachusetts high school. Data given include: monthly and daily electrical energy yield; monthly and daily insolation; monthly and daily array efficiency; energy production as a function of power level, voltage, cell temperature, and hour of day; insolation as a function of hour of the day; input, output and efficiency for each of two power conditioning units and for the total power conditioning system; energy supplied to the load by the photovoltaic system and by the grid; photovoltaic system efficiency; dollar value of the energy supplied by the photovoltaic system; capacity factor; daily photovoltaic energy to load; daily system availability and hours of daylight; heating and cooling degree days; hourly cell temperature, ambient temperature, wind speed, and insolation; average monthly wind speed; wind direction distribution; and daily data acquisition mode and recording interval plot.

The CMOS integration of a power inverter

NASA Astrophysics Data System (ADS)

Mannarino, Eric Francis

Due to their falling costs, the use of renewable energy systems is expanding around the world. These systems require the conversion of DC power into grid-synchronous AC power. Currently, the inverters that carry out this task are built using discrete transistors. TowerJazz Semiconductor Corp. has created a commercial CMOS process that allows for blocking voltages of up to 700 V, effectively removing the barrier to integrating power inverters onto a single chip. This thesis explores this process using two topologies. The first is a cell-based switched-capacitor topology first presented by Ke Zou. The second is a novel topology that explores the advantage of using a bused input-output system, as in digital electronics. Simulations run on both topologies confirm the high-efficiency demonstrated in Zou’s process as well as the advantage the bus-based system has in output voltage levels.

Intermediate photovoltaic system application experiment operational performance report: Volume 5, for Beverly High School, Beverly, Mass.

NASA Astrophysics Data System (ADS)

1982-02-01

Performance data for the month of January, 1982 for a grid connected photovoltaic power supply in Massachusetts are presented. Data include: monthly and daily electrical energy produced; monthly and daily solar energy incident on the array; monthly and daily array efficiency; plots of energy produced as a function of power level, voltage, cell temperature and time of day; power conditioner input, output and efficiency for each of two individual units and for the total power conditioning system; photovoltaic system efficiency; capacity factor; PV system to load and grid to load energies and corresponding dollar values; daily energy supplies to the load by the PV system; daily PV system availability; monthly and hourly insolation; monthly and hourly temperature average; monthly and hourly wind speed; wind direction distribution; average heating and cooling degree days; number of freeze/thaw cycles; and the data acquisition mode and recording interval plot.

Bosch CO2 Reduction System Development

NASA Technical Reports Server (NTRS)

Holmes, R. F.; King, C. D.; Keller, E. E.

1975-01-01

Refinements in the design of a Bosch CO2 reduction unit for spacecraft O2 production are described. Sealing of the vacuum insulation jacket was simplified so that high vacuum and high insulation performance are easily maintained. The device includes a relatively simple concentric shell recuperative heat exchanger which operates at approximately 95% temperature effectiveness and helps lower power consumption. The influence of reactor temperature, pressure, and recycle gas composition on power consumption was investigated. In general, precise control is not required since power consumption is not very sensitive to moderate variations of these parameters near their optimum values. There are two process rate control modes which match flow rate to process demand. Catalyst conditioning, support, and packing pattern developments assure consistent starts, reduced energy consumption, and extended cartridge life. Operation levels for four or five men were maintained with overall power input values of 50 to 60 watts per man.

Stability testing and analysis of a PMAD dc test bed for the Space Station Freedom

NASA Technical Reports Server (NTRS)

Button, Robert M.; Brush, Andrew S.

1992-01-01

The Power Management and Distribution (PMAD) dc Test Bed at the NASA Lewis Research Center is introduced. Its usefulness to the Space Station Freedom Electrical Power (EPS) development and design are discussed in context of verifying system stability. Stability criteria developed by Middlebrook and Cuk are discussed as they apply to constant power dc to dc converters exhibiting negative input impedance at low frequencies. The utility-type Secondary Subsystem is presented and each component is described. The instrumentation used to measure input and output impedance under load is defined. Test results obtained from input and output impedance measurements of test bed components are presented. It is shown that the PMAD dc Test Bed Secondary Subsystem meets the Middlebrook stability criterion for certain loading conditions.

Stability Testing and Analysis of a PMAD DC Test Bed for the Space Station Freedom

NASA Technical Reports Server (NTRS)

Button, Robert M.; Brush, Andrew S.

1992-01-01

The Power Management and Distribution (PMAD) DC Test Bed at the NASA Lewis Research Center is introduced. Its usefulness to the Space Station Freedom Electrical Power (EPS) development and design are discussed in context of verifying system stability. Stability criteria developed by Middlebrook and Cuk are discussed as they apply to constant power DC to DC converters exhibiting negative input impedance at low frequencies. The utility-type Secondary Subsystem is presented and each component is described. The instrumentation used to measure input and output impedance under load is defined. Test results obtained from input and output impedance measurements of test bed components are presented. It is shown that the PMAD DC Test Bed Secondary Subsystem meets the Middlebrook stability criterion for certain loading conditions.

Status of the NEXT Ion Thruster Long Duration Test

NASA Technical Reports Server (NTRS)

Frandina, Michael M.; Arrington, Lynn A.; Soulas, George C.; Hickman, Tyler A.; Patterson, Michael J.

2005-01-01

The status of NASA's Evolutionary Xenon Thruster (NEXT) Long Duration Test (LDT) is presented. The test will be conducted with a 36 cm diameter engineering model ion thruster, designated EM3, to validate and qualify the NEXT thruster propellant throughput capability of 450 kg xenon. The ion thruster will be operated at various input powers from the NEXT throttle table. Pretest performance assessments demonstrated that EM3 satisfies all thruster performance requirements. As of June 26, 2005, the ion thruster has accumulated 493 hours of operation and processed 10.2 kg of xenon at a thruster input power of 6.9 kW. Overall ion thruster performance, which includes thrust, thruster input power, specific impulse, and thrust efficiency, has been steady to date with very little variation in performance parameters.

Optically-powered Voltage-supply-device for Effective Utilization of Optical Energy in the Fiber-To-The-Home Network

NASA Astrophysics Data System (ADS)

Fukano, Hideki; Shinagawa, Takeshi; Tsuruta, Kenji

An optically powered device with using InGaAs-Photodiode has been developed. This study aims to harvest light energy (2.8∼500μW) from the FTTH (Fiber To The Home) network and to utilize it for operating remote sensors without external energy sources. First, we designed and evaluated the characteristics of the booster circuit and confirmed that it could boost an input voltage of 0.3 V to 3.0 V. Next, we also evaluated the characteristics of InGaAs photodiode and confirmed that it can output a voltage over 0.3 V at 10-μW input light. We demonstrate that a ready-made sensor can be operated with an input optical power as low as 10 μW.

Active C4 Electrodes for Local Field Potential Recording Applications

PubMed Central

Wang, Lu; Freedman, David; Sahin, Mesut; Ünlü, M. Selim; Knepper, Ronald

2016-01-01

Extracellular neural recording, with multi-electrode arrays (MEAs), is a powerful method used to study neural function at the network level. However, in a high density array, it can be costly and time consuming to integrate the active circuit with the expensive electrodes. In this paper, we present a 4 mm × 4 mm neural recording integrated circuit (IC) chip, utilizing IBM C4 bumps as recording electrodes, which enable a seamless active chip and electrode integration. The IC chip was designed and fabricated in a 0.13 μm BiCMOS process for both in vitro and in vivo applications. It has an input-referred noise of 4.6 μVrms for the bandwidth of 10 Hz to 10 kHz and a power dissipation of 11.25 mW at 2.5 V, or 43.9 μW per input channel. This prototype is scalable for implementing larger number and higher density electrode arrays. To validate the functionality of the chip, electrical testing results and acute in vivo recordings from a rat barrel cortex are presented. PMID:26861324

Power in methods: language to infants in structured and naturalistic contexts.

PubMed

Tamis-LeMonda, Catherine S; Kuchirko, Yana; Luo, Rufan; Escobar, Kelly; Bornstein, Marc H

2017-11-01

Methods can powerfully affect conclusions about infant experiences and learning. Data from naturalistic observations may paint a very different picture of learning and development from those based on structured tasks, as illustrated in studies of infant walking, object permanence, intention understanding, and so forth. Using language as a model system, we compared the speech of 40 mothers to their 13-month-old infants during structured play and naturalistic home routines. The contrasting methods yielded unique portrayals of infant language experiences, while simultaneously underscoring cross-situational correspondence at an individual level. Infants experienced substantially more total words and different words per minute during structured play than they did during naturalistic routines. Language input during structured play was consistently dense from minute to minute, whereas language during naturalistic routines showed striking fluctuations interspersed with silence. Despite these differences, infants' language experiences during structured play mirrored the peak language interactions infants experienced during naturalistic routines, and correlations between language inputs in the two conditions were strong. The implications of developmental methods for documenting the nature of experiences and individual differences are discussed. © 2017 John Wiley & Sons Ltd.

Straight and chopped dc performance data for a General Electric 5BT 2366C10 motor and an EV-1 controller

NASA Technical Reports Server (NTRS)

Edie, P. C.

1981-01-01

Performance data on the General Electric 5BT 2366C10 series wound dc motor and EV-1 Chopper Controller is supplied for the electric vehicle manufacturer. Data is provided for both straight and chopped dc input to the motor, at 2 motor temperature levels. Testing was done at 6 voltage increments to the motor, and 2 voltage increments to the controller. Data results are presented in both tabular and graphical forms. Tabular information includes motor voltage and current input data, motor speed and torque output data, power data and temperature data. Graphical information includes torque-speed, motor power output-speed, torque-current, and efficiency-speed plots under the various operating conditions. The data resulting from this testing shows the speed-torque plots to have the most variance with operating temperature. The maximum motor efficiency is between 86% and 87%, regardless of temperature or mode of operation. When the chopper is utilized, maximum motor efficiency occurs when the chopper duty cycle approaches 100%.

Input Power Characteristics of a Three-Phase Thyristor Converter

DOT National Transportation Integrated Search

1973-10-01

A phase delay rectifier operating into a passive resistive load was instrumented in the laboratory. Techniques for accurate measurement of power, displacement reactive power, harmonic components, and distortion reactive power are presented. The chara...

xLPR Sim Editor 1.0 User's Guide

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

Mariner, Paul E.

2017-03-01

The United States Nuclear Regulatory Commission in cooperation with the Electric Power Research Institute contracted Sandia National Laboratories to develop the framework of a probabilistic fracture mechanics assessment code called xLPR ( Extremely Low Probability of Rupture) Version 2.0 . The purpose of xLPR is to evaluate degradation mechanisms in piping systems at nuclear power plants and to predict the probability of rupture. This report is a user's guide for xLPR Sim Editor 1.0 , a graphical user interface for creating and editing the xLPR Version 2.0 input file and for creating, editing, and using the xLPR Version 2.0 databasemore » files . The xLPR Sim Editor, provides a user - friendly way for users to change simulation options and input values, s elect input datasets from xLPR data bases, identify inputs needed for a simulation, and create and modify an input file for xLPR.« less

A low power low noise analog front end for portable healthcare system

NASA Astrophysics Data System (ADS)

Yanchao, Wang; Keren, Ke; Wenhui, Qin; Yajie, Qin; Ting, Yi; Zhiliang, Hong

2015-10-01

The presented analog front end (AFE) used to process human bio-signals consists of chopping instrument amplifier (IA), chopping spikes filter and programmable gain and bandwidth amplifier. The capacitor-coupling input of AFE can reject the DC electrode offset. The power consumption of current-feedback based IA is reduced by adopting capacitor divider in the input and feedback network. Besides, IA's input thermal noise is decreased by utilizing complementary CMOS input pairs which can offer higher transconductance. Fabricated in Global Foundry 0.35 μm CMOS technology, the chip consumes 3.96 μA from 3.3 V supply. The measured input noise is 0.85 μVrms (0.5-100 Hz) and the achieved noise efficient factor is 6.48. Project supported by the Science and Technology Commission of Shanghai Municipality (No. 13511501100), the State Key Laboratory Project of China (No. 11MS002), and the State Key Laboratory of ASIC & System, Fudan University.

Impedance Matching Antenna-Integrated High-Efficiency Energy Harvesting Circuit

PubMed Central

Shinki, Yuharu; Shibata, Kyohei; Mansour, Mohamed

2017-01-01

This paper describes the design of a high-efficiency energy harvesting circuit with an integrated antenna. The circuit is composed of series resonance and boost rectifier circuits for converting radio frequency power into boosted direct current (DC) voltage. The measured output DC voltage is 5.67 V for an input of 100 mV at 900 MHz. Antenna input impedance matching is optimized for greater efficiency and miniaturization. The measured efficiency of this antenna-integrated energy harvester is 60% for −4.85 dBm input power and a load resistance equal to 20 kΩ at 905 MHz. PMID:28763043

Impedance Matching Antenna-Integrated High-Efficiency Energy Harvesting Circuit.

PubMed

Shinki, Yuharu; Shibata, Kyohei; Mansour, Mohamed; Kanaya, Haruichi

2017-08-01

This paper describes the design of a high-efficiency energy harvesting circuit with an integrated antenna. The circuit is composed of series resonance and boost rectifier circuits for converting radio frequency power into boosted direct current (DC) voltage. The measured output DC voltage is 5.67 V for an input of 100 mV at 900 MHz. Antenna input impedance matching is optimized for greater efficiency and miniaturization. The measured efficiency of this antenna-integrated energy harvester is 60% for -4.85 dBm input power and a load resistance equal to 20 kΩ at 905 MHz.

Device and method for measuring the coefficient of performance of a heat pump

DOEpatents

Brantley, V.R.; Miller, D.R.

1982-05-18

A method and instrument is provided which allows quick and accurate measurement of the coefficient of performance of an installed electrically powered heat pump including auxiliary resistane heaters. Temperature-sensitive resistors are placed in the return and supply air ducts to measure the temperature increase of the air across the refrigerant and resistive-heating elements of the system. The voltages across the resistors which are directly proportional to the respective duct tempertures are applied to the inputs of a differential amplifier so that its output voltage is proportional to the temperature difference across the unit. A voltage-to-frequency converter connected to the output of the differential amplifier converts the voltage signal to a proportional-frequency signal. A digital watt meter is used to measure the power to the unit and produces a signal having a frequency proportional to the input power. A digital logic circuit ratios the temperature difference signal and the electric power input signal in a unique manner to produce a single number which is the coefficient of performance of the unit over the test interval. The digital logic and an in-situ calibration procedure enables the instrument to make these measurements in such a way that the ratio of heat flow/power input is obtained without computations. No specialized knowledge of thermodynamics or electrons is required to operate the instrument.

Device and method for measuring the coefficient of performance of a heat pump

DOEpatents

Brantley, Vanston R.; Miller, Donald R.

1984-01-01

A method and instrument is provided which allows quick and accurate measurement of the coefficient of performance of an installed electrically powered heat pump including auxiliary resistance heaters. Temperature sensitive resistors are placed in the return and supply air ducts to measure the temperature increase of the air across the refrigerant and resistive heating elements of the system. The voltages across the resistors which are directly proportional to the respective duct temperatures are applied to the inputs of a differential amplifier so that its output voltage is proportional to the temperature difference across the unit. A voltage-to-frequency converter connected to the output of the differential amplifier converts the voltage signal to a proportional frequency signal. A digital watt meter is used to measure the power to the unit and produces a signal having a frequency proportional to the input power. A digital logic circuit ratios the temperature difference signal and the electric power input signal in a unique manner to produce a single number which is the coefficient of performance of the unit over the test interval. The digital logic and an in-situ calibration procedure enables the instrument to make these measurements in such a way that the ratio of heat flow/power input is obtained without computations. No specialized knowledge of thermodynamics or electronics is required to operate the instrument.

Modeling of a resonant heat engine

NASA Astrophysics Data System (ADS)

Preetham, B. S.; Anderson, M.; Richards, C.

2012-12-01

A resonant heat engine in which the piston assembly is replaced by a sealed elastic cavity is modeled and analyzed. A nondimensional lumped-parameter model is derived and used to investigate the factors that control the performance of the engine. The thermal efficiency predicted by the model agrees with that predicted from the relation for the Otto cycle based on compression ratio. The predictions show that for a fixed mechanical load, increasing the heat input results in increased efficiency. The output power and power density are shown to depend on the loading for a given heat input. The loading condition for maximum output power is different from that required for maximum power density.

Multiple output power supply circuit for an ion engine with shared upper inverter

NASA Technical Reports Server (NTRS)

Cardwell, Jr., Gilbert I. (Inventor); Phelps, Thomas K. (Inventor)

2001-01-01

A power supply circuit for an ion engine suitable for a spacecraft is coupled to a bus having a bus input and a bus return. The power supply circuit has a first primary winding of a first transformer. An upper inverter circuit is coupled to the bus input and the first primary winding. The power supply circuit further includes a first lower inverter circuit coupled to the bus return and the first primary winding. The second primary winding of a second transformer is coupled to the upper inverter circuit. A second lower inverter circuit is coupled to the bus return and the second primary winding.

A Within-subjects Experimental Protocol to Assess the Effects of Social Input on Infant EEG.

PubMed

St John, Ashley M; Kao, Katie; Chita-Tegmark, Meia; Liederman, Jacqueline; Grieve, Philip G; Tarullo, Amanda R

2017-05-03

Despite the importance of social interactions for infant brain development, little research has assessed functional neural activation while infants socially interact. Electroencephalography (EEG) power is an advantageous technique to assess infant functional neural activation. However, many studies record infant EEG only during one baseline condition. This protocol describes a paradigm that is designed to comprehensively assess infant EEG activity in both social and nonsocial contexts as well as tease apart how different types of social inputs differentially relate to infant EEG. The within-subjects paradigm includes four controlled conditions. In the nonsocial condition, infants view objects on computer screens. The joint attention condition involves an experimenter directing the infant's attention to pictures. The joint attention condition includes three types of social input: language, face-to-face interaction, and the presence of joint attention. Differences in infant EEG between the nonsocial and joint attention conditions could be due to any of these three types of input. Therefore, two additional conditions (one with language input while the experimenter is hidden behind a screen and one with face-to-face interaction) were included to assess the driving contextual factors in patterns of infant neural activation. Representative results demonstrate that infant EEG power varied by condition, both overall and differentially by brain region, supporting the functional nature of infant EEG power. This technique is advantageous in that it includes conditions that are clearly social or nonsocial and allows for examination of how specific types of social input relate to EEG power. This paradigm can be used to assess how individual differences in age, affect, socioeconomic status, and parent-infant interaction quality relate to the development of the social brain. Based on the demonstrated functional nature of infant EEG power, future studies should consider the role of EEG recording context and design conditions that are clearly social or nonsocial.

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.

Microwave applicator for in-drum processing of radioactive waste slurry

DOEpatents

White, T.L.

1994-06-28

A microwave applicator for processing of radioactive waste slurry uses a waveguide network which splits an input microwave of TE[sub 10] rectangular mode to TE[sub 01] circular mode. A cylindrical body has four openings, each receiving 1/4 of the power input. The waveguide network includes a plurality of splitters to effect the 1/4 divisions of power. 4 figures.

Evaluation of the power consumption of a high-speed parallel robot

NASA Astrophysics Data System (ADS)

Han, Gang; Xie, Fugui; Liu, Xin-Jun

2018-06-01

An inverse dynamic model of a high-speed parallel robot is established based on the virtual work principle. With this dynamic model, a new evaluation method is proposed to measure the power consumption of the robot during pick-and-place tasks. The power vector is extended in this method and used to represent the collinear velocity and acceleration of the moving platform. Afterward, several dynamic performance indices, which are homogenous and possess obvious physical meanings, are proposed. These indices can evaluate the power input and output transmissibility of the robot in a workspace. The distributions of the power input and output transmissibility of the high-speed parallel robot are derived with these indices and clearly illustrated in atlases. Furtherly, a low-power-consumption workspace is selected for the robot.

Power Electronics Development for the SPT-100 Thruster

NASA Technical Reports Server (NTRS)

Hamley, John A.; Hill, Gerald M.; Sankovic, John M.

1994-01-01

Russian electric propulsion technologies have recently become available on the world market. Of significant interest is the Stationary Plasma Thruster (SPT) which has a significant flight heritage in the former Soviet space program. The SPT has performance levels of up to 1600 seconds of specific impulse at a thrust efficiency of 0.50. Studies have shown that this level of performance is well suited for stationkeeping applications, and the SPT-100, with a 1.35 kW input power level, is presently being evaluated for use on Western commercial satellites. Under a program sponsored by the Innovative Science and Technology Division of the Ballistic Missile Defense Organization, a team of U.S. electric propulsion specialists observed the operation of the SPT-100 in Russia. Under this same program, power electronics were developed to operate the SPT-100 to characterize thruster performance and operation in the U.S. The power electronics consisted of a discharge, cathode heater, and pulse igniter power supplies to operate the thruster with manual flow control. A Russian designed matching network was incorporated in the discharge supply to ensure proper operation with the thruster. The cathode heater power supply and igniter were derived from ongoing development projects. No attempts were made to augment thruster electromagnet current in this effort. The power electronics successfully started and operated the SPT-100 thruster in performance tests at NASA Lewis, with minimal oscillations in the discharge current. The efficiency of the main discharge supply was measured at 0.92, and straightforward modifications were identified which could increase the efficiency to 0.94.

Status of the NEXT Ion Thruster Long-Duration Test After 10,100 hr and 207 kg Demonstrated

NASA Technical Reports Server (NTRS)

Herman, Daniel A.; Soulas, George C.; Patterson, Michael J.

2008-01-01

The NASA s Evolutionary Xenon Thruster (NEXT) program is developing the next-generation ion propulsion system with significant enhancements beyond the state-of-the-art in ion propulsion to provide future NASA science missions with enhanced mission capabilities at a low total development cost. As part of a comprehensive thruster service life assessment utilizing both testing and analyses, a Long-Duration Test (LDT) was initiated to validate and qualify the NEXT propellant throughput capability to a qualification-level of 450 kg, 1.5 times the mission-derived throughput requirement of 300 kg. This wear test is being conducted with a modified, flight-representative NEXT engineering model ion thruster, designated EM3. As of June 21, 2007, the thruster has accumulated 10,100 hr of operation at the thruster full-input-power of 6.9 kW with 3.52 A beam current and 1800 V beam power supply voltage. The thruster has processed 207 kg of xenon and demonstrated a total impulse of 8.5 106 N-s; the highest total impulse ever demonstrated by an ion thruster in the history of space propulsion. Thruster performance tests are conducted periodically over the entire NEXT throttle table with input power ranging 0.5 to 6.9 kW. Overall ion thruster performance parameters including thrust, input power, specific impulse, and thruster efficiency have been nominal with little variation to date. Lifetime-limiting component erosion rates have been consistent with the NEXT service life assessment, which predicts the earliest failure sometime after 750 kg of xenon propellant throughput; well beyond the mission-derived lifetime requirement. The NEXT wear test data confirm that the erosion of the discharge keeper orifice, enlarging of nominal-current-density accelerator grid aperture cusps, and the decrease in cold grid-gap observed during the NSTAR Extended Life Test have been mitigated. This paper presents the status of the NEXT LDT to date.

Relations between the efficiency, power and dissipation for linear irreversible heat engine at maximum trade-off figure of merit

NASA Astrophysics Data System (ADS)

Iyyappan, I.; Ponmurugan, M.

2018-03-01

A trade of figure of merit (\\dotΩ ) criterion accounts the best compromise between the useful input energy and the lost input energy of the heat devices. When the heat engine is working at maximum \\dotΩ criterion its efficiency increases significantly from the efficiency at maximum power. We derive the general relations between the power, efficiency at maximum \\dotΩ criterion and minimum dissipation for the linear irreversible heat engine. The efficiency at maximum \\dotΩ criterion has the lower bound \

Novel Driving Control of Power Assisted Wheelchair Based on Minimum Jerk Trajectory

NASA Astrophysics Data System (ADS)

Seki, Hirokazu; Sugimoto, Takeaki; Tadakuma, Susumu

This paper describes a novel trajectory control scheme for power assisted wheelchair. Human input torque patterns are always intermittent in power assisted wheelchairs, therefore, the suitable trajectories must be generated also after the human decreases his/her input torque. This paper tries to solve this significant problem based on minimum jerk model minimizing the changing rate of acceleration. The proposed control system based on minimum jerk trajectory is expected to improve the ride quality, stability and safety. Some experiments show the effectiveness of the proposed method.

Self-seeded injection-locked FEL amplifer

DOEpatents

Sheffield, Richard L.

1999-01-01

A self-seeded free electron laser (FEL) provides a high gain and extraction efficiency for the emitted light. An accelerator outputs a beam of electron pulses to a permanent magnet wiggler having an input end for receiving the electron pulses and an output end for outputting light and the electron pulses. An optical feedback loop collects low power light in a small signal gain regime at the output end of said wiggler and returns the low power light to the input end of the wiggler while outputting high power light in a high signal gain regime.

Computer program to predict aircraft noise levels

NASA Technical Reports Server (NTRS)

Clark, B. J.

1981-01-01

Methods developed at the NASA Lewis Research Center for predicting the noise contributions from various aircraft noise sources were programmed to predict aircraft noise levels either in flight or in ground tests. The noise sources include fan inlet and exhaust, jet, flap (for powered lift), core (combustor), turbine, and airframe. Noise propagation corrections are available for atmospheric attenuation, ground reflections, extra ground attenuation, and shielding. Outputs can include spectra, overall sound pressure level, perceived noise level, tone-weighted perceived noise level, and effective perceived noise level at locations specified by the user. Footprint contour coordinates and approximate footprint areas can also be calculated. Inputs and outputs can be in either System International or U.S. customary units. The subroutines for each noise source and propagation correction are described. A complete listing is given.

Design and implementation of an audio indicator

NASA Astrophysics Data System (ADS)

Zheng, Shiyong; Li, Zhao; Li, Biqing

2017-04-01

This page proposed an audio indicator which designed by using C9014, LED by operational amplifier level indicator, the decimal count/distributor of CD4017. The experimental can control audibly neon and holiday lights through the signal. Input audio signal after C9014 composed of operational amplifier for power amplifier, the adjust potentiometer extraction amplification signal input voltage CD4017 distributors make its drive to count, then connect the LED display running situation of the circuit. This simple audio indicator just use only U1 and can produce two colors LED with the audio signal tandem come pursuit of the running effect, from LED display the running of the situation takes can understand the general audio signal. The variation in the audio and the frequency of the signal and the corresponding level size. In this light can achieve jump to change, slowly, atlas, lighting four forms, used in home, hotel, discos, theater, advertising and other fields, and a wide range of USES, rU1h life in a modern society.

Multi-service highly sensitive rectifier for enhanced RF energy scavenging.

PubMed

Shariati, Negin; Rowe, Wayne S T; Scott, James R; Ghorbani, Kamran

2015-05-07

Due to the growing implications of energy costs and carbon footprints, the need to adopt inexpensive, green energy harvesting strategies are of paramount importance for the long-term conservation of the environment and the global economy. To address this, the feasibility of harvesting low power density ambient RF energy simultaneously from multiple sources is examined. A high efficiency multi-resonant rectifier is proposed, which operates at two frequency bands (478-496 and 852-869 MHz) and exhibits favorable impedance matching over a broad input power range (-40 to -10 dBm). Simulation and experimental results of input reflection coefficient and rectified output power are in excellent agreement, demonstrating the usefulness of this innovative low-power rectification technique. Measurement results indicate an effective efficiency of 54.3%, and an output DC voltage of 772.8 mV is achieved for a multi-tone input power of -10 dBm. Furthermore, the measured output DC power from harvesting RF energy from multiple services concurrently exhibits a 3.14 and 7.24 fold increase over single frequency rectification at 490 and 860 MHz respectively. Therefore, the proposed multi-service highly sensitive rectifier is a promising technique for providing a sustainable energy source for low power applications in urban environments.

Multi-Service Highly Sensitive Rectifier for Enhanced RF Energy Scavenging

PubMed Central

Shariati, Negin; Rowe, Wayne S. T.; Scott, James R.; Ghorbani, Kamran

2015-01-01

Due to the growing implications of energy costs and carbon footprints, the need to adopt inexpensive, green energy harvesting strategies are of paramount importance for the long-term conservation of the environment and the global economy. To address this, the feasibility of harvesting low power density ambient RF energy simultaneously from multiple sources is examined. A high efficiency multi-resonant rectifier is proposed, which operates at two frequency bands (478–496 and 852–869 MHz) and exhibits favorable impedance matching over a broad input power range (−40 to −10 dBm). Simulation and experimental results of input reflection coefficient and rectified output power are in excellent agreement, demonstrating the usefulness of this innovative low-power rectification technique. Measurement results indicate an effective efficiency of 54.3%, and an output DC voltage of 772.8 mV is achieved for a multi-tone input power of −10 dBm. Furthermore, the measured output DC power from harvesting RF energy from multiple services concurrently exhibits a 3.14 and 7.24 fold increase over single frequency rectification at 490 and 860 MHz respectively. Therefore, the proposed multi-service highly sensitive rectifier is a promising technique for providing a sustainable energy source for low power applications in urban environments. PMID:25951137

Diamond Heat-Spreader for Submillimeter-Wave Frequency Multipliers

NASA Technical Reports Server (NTRS)

Lin, Robert H.; Schlecht, Erich T.; Chattopadhyay, Goutam; Gill, John J.; Mehdi, Imran; Siegel, Peter H.; Ward, John S.; Lee, Choonsup; Thomas, Bertrand C.; Maestrini, Alain

2010-01-01

The planar GaAs Shottky diode frequency multiplier is a critical technology for the local oscillator (LO) for submillimeter- wave heterodyne receivers due to low mass, tenability, long lifetime, and room-temperature operation. The use of a W-band (75-100 GHz) power amplifier followed by a frequency multiplier is the most common for submillimeter-wave sources. Its greatest challenge is to provide enough input power to the LO for instruments onboard future planetary missions. Recently, JPL produced 800 mW at 92.5 GHz by combining four MMICs in parallel in a balanced configuration. As more power at W-band is available to the multipliers, their power-handling capability be comes more important. High operating temperatures can lead to degradation of conversion efficiency or catastrophic failure. The goal of this innovation is to reduce the thermal resistance by attaching diamond film as a heat-spreader on the backside of multipliers to improve their power-handling capability. Polycrystalline diamond is deposited by hot-filament chemical vapor deposition (CVD). This diamond film acts as a heat-spreader to both the existing 250- and 300-GHz triplers, and has a high thermal conductivity (1,000-1,200 W/mK). It is approximately 2.5 times greater than copper (401 W/mK) and 20 times greater than GaAs (46 W/mK). It is an electrical insulator (resistivity approx. equals 10(exp 15) Ohms-cm), and has a low relative dielectric constant of 5.7. Diamond heat-spreaders reduce by at least 200 C at 250 mW of input power, compared to the tripler without diamond, according to thermal simulation. This superior thermal management provides a 100-percent increase in power-handling capability. For example, with this innovation, 40-mW output power has been achieved from a 250-GHz tripler at 350-mW input power, while the previous triplers, without diamond, suffered catastrophic failures. This breakthrough provides a stepping-stone for frequency multipliers-based LO up to 3 THz. The future work for this design is to apply the high output power from both the 250 and 300 GHz to multiple chains in order to generate milliwatts at 2.3 THz. Using the first generation of results for this innovation, 40 mW of output power were produced from a 240-GHz tripler at 350-mW input power, and 27- mW output power was produced from a 300-GHz tripler at 408-mW input power. This is two times higher than the current state-of-the-art output power capability. A finite-element thermal simulation also shows that 30-microns thick diamond dropped the temperature of the anodes by at least 200 C.

Evaluation of Advanced Stirling Convertor Net Heat Input Correlation Methods Using a Thermal Standard

NASA Technical Reports Server (NTRS)

Briggs, Maxwell; Schifer, Nicholas

2011-01-01

Test hardware used to validate net heat prediction models. Problem: Net Heat Input cannot be measured directly during operation. Net heat input is a key parameter needed in prediction of efficiency for convertor performance. Efficiency = Electrical Power Output (Measured) divided by Net Heat Input (Calculated). Efficiency is used to compare convertor designs and trade technology advantages for mission planning.

Fuel Cell/Electrochemical Cell Voltage Monitor

NASA Technical Reports Server (NTRS)

Vasquez, Arturo

2012-01-01

A concept has been developed for a new fuel cell individual-cell-voltage monitor that can be directly connected to a multi-cell fuel cell stack for direct substack power provisioning. It can also provide voltage isolation for applications in high-voltage fuel cell stacks. The technology consists of basic modules, each with an 8- to 16-cell input electrical measurement connection port. For each basic module, a power input connection would be provided for direct connection to a sub-stack of fuel cells in series within the larger stack. This power connection would allow for module power to be available in the range of 9-15 volts DC. The relatively low voltage differences that the module would encounter from the input electrical measurement connection port, coupled with the fact that the module's operating power is supplied by the same substack voltage input (and so will be at similar voltage), provides for elimination of high-commonmode voltage issues within each module. Within each module, there would be options for analog-to-digital conversion and data transfer schemes. Each module would also include a data-output/communication port. Each of these ports would be required to be either non-electrical (e.g., optically isolated) or electrically isolated. This is necessary to account for the fact that the plurality of modules attached to the stack will normally be at a range of voltages approaching the full range of the fuel cell stack operating voltages. A communications/ data bus could interface with the several basic modules. Options have been identified for command inputs from the spacecraft vehicle controller, and for output-status/data feeds to the vehicle.

VLF Transmitter Signal Power Loss to Quasi-Electrostatic Whistler Mode Waves in Regions Containing Plasma Density Irregularities

NASA Astrophysics Data System (ADS)

Bell, T. F.; Foust, F.; Inan, U. S.; Lehtinen, N. G.

2010-12-01

The energetic particles comprising the Earth’s radiation belts are an important component of Space Weather. The commonly accepted model of the quasi-steady radiation belts developed by Abel and Thorne [1998] proposes that VLF signals from powerful ground based transmitters determine the lifetimes of energetic radiation belt electrons (100 keV-1.5 MeV) on L shells in the range 1.3-2.8. The primary mechanism of interaction is pitch angle scattering during gyro-resonance. Recent observations [Starks et al., 2008] from multiple spacecraft suggest that the actual night time intensity of VLF transmitter signals in the radiation belts is approximately 20 dB below the level assumed in the Abel and Thorne model and approximately 10 dB below model values during the day. In this work we discuss one mechanism which might be responsible for a large portion of this intensity discrepancy. The mechanism is linear mode coupling between electromagnetic whistler mode waves and quasi-electrostatic whistler mode waves. As VLF electromagnetic whistler mode waves propagate through regions containing small scale (2-100 m) magnetic-field-aligned plasma density irregularities, they excite quasi-electrostatic whistler mode waves, and this excitation represents a power loss for the input waves. We construct plausible models of the irregularities in order to use numerical simulations to determine the characteristics of the mode coupling mechanism and the conditions under which the input VLF waves can lose significant power to the excited quasi-electrostatic whistler mode waves.

Solid-state laser source of narrowband ultraviolet B light for skin disease care

NASA Astrophysics Data System (ADS)

Tarasov, Aleksandr A.; Chu, Hong

2013-03-01

We report about the development of all-solid-state laser source of narrowband UV-B light for medical applications. The device is based on a gain-switched Ti: Sapphire laser with volume Bragg grating, pumped at 532 nm and operating at 931.8 nm, followed by a third harmonic generator and a fiber optic beam homogenizer. The maximum available pulse energy exceeded 5 mJ at 310.6 nm, with a pulse repetition rates of 50 Hz. The output characteristics satisfy the medical requirements for psoriasis and vitiligo treatment. A new optical scheme for third harmonic generation enhancement at moderate levels of input intensities is proposed and investigated. As a result, 40% harmonic efficiency was obtained, when input pulse power was only 300 kW.

High energy efficient solid state laser sources

NASA Technical Reports Server (NTRS)

Byer, Robert L.

1987-01-01

Diode-laser-pumped solid-state laser oscillators and nonlinear processes were investigated. A new generation on nonplanar oscillator was fabricated, and it is anticipated that passive linewidths will be pushed to the kilohertz regime. A number of diode-pumped laser transitions were demonstrated in the rod configuration. Second-harmonic conversion efficiencies as high as 15% are routinely obtained in a servo-locked external resonant doubling crystal at 15 mW cw input power levels at 1064 nm.

Develop Measures of Effectiveness and Deployment Optimization Rules for Networked Ground Micro-Sensors

DTIC Science & Technology

2001-05-01

types and total #) Ø Control of Sensors ( Scheduling ) Ø Coverage (Time & Area) Uncontrollable Inputs ØWeather Ø Atmospheric Effects Ø Equipment...are widely scattered and used to cue or wakeup other higher-level sensors. Trip line sensors consist of some combination of acoustic, seismic and...Employ a mix if different sensor types in order to increase detection probability 4.4.4.2 Minimize Battery Power • Set schedule turn on and off

Ka-Band Waveguide Two-Way Hybrid Combiner for MMIC Amplifiers

NASA Technical Reports Server (NTRS)

Simons, Rainee N.; Chevalier, Christine T.; Wintucky, Edwin G.; Freeman, Jon C.

2010-01-01

The design, simulation, and characterization of a novel Ka-band (32.05 0.25 GHz) rectangular waveguide two-way branch-line hybrid unequal power combiner (with port impedances matched to that of a standard WR-28 waveguide) has been created to combine input signals, which are in phase and with an amplitude ratio of two. The measured return loss and isolation of the branch-line hybrid are better than 22 and 27 dB, respectively. The measured combining efficiency is 92.9 percent at the center frequency of 32.05 GHz. This circuit is efficacious in combining the unequal output power from two Ka-band GaAs pseudomorphic high electron mobility transistor (pHEMT) monolithic microwave integrated circuit (MMIC) power amplifiers (PAs) with high efficiency. The component parts include the branch-line hybrid-based power combiner and the MMIC-based PAs. A two-way branch-line hybrid is a four-port device with all ports matched; power entering port 1 is divided in phase, and into the ratio 2:1 between ports 3 and 4. No power is coupled to port 2. MMICs are a type of integrated circuit fabricated on GaAs that operates at microwave frequencies, and performs the function of signal amplification. The power combiner is designed to operate over the frequency band of 31.8 to 32.3 GHz, which is NASA's deep space frequency band. The power combiner would have an output return loss better than 20 dB. Isolation between the output port and the isolated port is greater than 25 dB. Isolation between the two input ports is greater than 25 dB. The combining efficiency would be greater than 90 percent when the ratio of the two input power levels is two. The power combiner is machined from aluminum with E-plane split-block arrangement, and has excellent reliability. The flexibility of this design allows the combiner to be customized for combining the power from MMIC PAs with an arbitrary power output ratio. In addition, it allows combining a low-power GaAs MMIC with a high-power GaN MMIC. The arbitrary port impedance allows matching the output impedance of the MMIC PA directly to the waveguide impedance without transitioning first into a transmission line with characteristic impedance of 50 ohms. Thus, by eliminating the losses associated with a transition, the overall SSPA efficiency is enhanced. For reducing the cost and weight when required in very large quantities, such as in the beam-forming networks of phased-array antenna systems, the combiner can be manufactured using metal-plated plastic. Two hybrid unequal power combiners can be cascaded to realize a non-binary combiner (for e.g., a three-way) and can be synergistically optimized for low VSWR (voltage standing wave ratio), low insertion loss, high isolation, and wide bandwidth using commercial off-the-shelf electromagnetic software design tools.

Average BER analysis of SCM-based free-space optical systems by considering the effect of IM3 with OSSB signals under turbulence channels.

PubMed

Lim, Wansu; Cho, Tae-Sik; Yun, Changho; Kim, Kiseon

2009-11-09

In this paper, we derive the average bit error rate (BER) of subcarrier multiplexing (SCM)-based free space optics (FSO) systems using a dual-drive Mach-Zehnder modulator (DD-MZM) for optical single-sideband (OSSB) signals under atmospheric turbulence channels. In particular, we consider the third-order intermodulation (IM3), a significant performance degradation factor, in the case of high input signal power systems. The derived average BER, as a function of the input signal power and the scintillation index, is employed to determine the optimum number of SCM users upon the designing FSO systems. For instance, when the user number doubles, the input signal power decreases by almost 2 dBm under the log-normal and exponential turbulence channels at a given average BER.

Traveling wave linear accelerator with RF power flow outside of accelerating cavities

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

Dolgashev, Valery A.

A high power RF traveling wave accelerator structure includes a symmetric RF feed, an input matching cell coupled to the symmetric RF feed, a sequence of regular accelerating cavities coupled to the input matching cell at an input beam pipe end of the sequence, one or more waveguides parallel to and coupled to the sequence of regular accelerating cavities, an output matching cell coupled to the sequence of regular accelerating cavities at an output beam pipe end of the sequence, and output waveguide circuit or RF loads coupled to the output matching cell. Each of the regular accelerating cavities hasmore » a nose cone that cuts off field propagating into the beam pipe and therefore all power flows in a traveling wave along the structure in the waveguide.« less

X-Band, 17-Watt Solid-State Power Amplifier

NASA Technical Reports Server (NTRS)

Mittskus, Anthony; Stone, Ernest; Boger, William; Burgess, David; Honda, Richard; Nuckolls, Carl

2005-01-01

An advanced solid-state power amplifier that can generate an output power of as much as 17 W at a design operating frequency of 8.4 GHz has been designed and constructed as a smaller, lighter, less expensive alternative to traveling-wave-tube X-band amplifiers and to prior solid-state X-band power amplifiers of equivalent output power. This amplifier comprises a monolithic microwave integrated circuit (MMIC) amplifier module and a power-converter module integrated into a compact package (see Figure 1). The amplifier module contains an input variable-gain amplifier (VGA), an intermediate driver stage, a final power stage, and input and output power monitors (see Figure 2). The VGA and the driver amplifier are 0.5-m GaAs-based metal semiconductor field-effect transistors (MESFETs). The final power stage contains four parallel high-efficiency, GaAs-based pseudomorphic high-electron-mobility transistors (PHEMTs). The gain of the VGA is voltage-variable over a range of 10 to 24 dB. To provide for temperature compensation of the overall amplifier gain, the gain-control voltage is generated by an operational-amplifier circuit that includes a resistor/thermistor temperature-sensing network. The driver amplifier provides a gain of 14 dB to an output power of 27 dBm to drive the four parallel output PHEMTs, each of which is nominally capable of putting out as much as 5 W. The driver output is sent to the input terminals of the four parallel PHEMTs through microstrip power dividers; the outputs of these PHEMTs are combined by microstrip power combiners (which are similar to the microstrip power dividers) to obtain the final output power of 17 W.

Novel High-Voltage, High-Power Piezoelectric Transformer Developed and Demonstrated for Space Communications Applications

NASA Technical Reports Server (NTRS)

Carazo, Alfredo V.; Wintucky, Edwin G.

2004-01-01

Improvements in individual piezoelectric transformer (PT) performance and the combination of these PTs in a unique modular topology under a Phase I contract with the NASA Glenn Research Center have enabled for the first time the simultaneous achievement of both high voltage and high power at much higher levels than previously obtained with any PT. Feasibility was demonstrated by a prototype transformer (called a Tap-Soner), which is shown in the preceding photograph as part of a direct-current to direct-current (dc-dc) converter having two outputs rated at 1.5 kV/5 W and 4.5 kV/20 W. The power density of 3.5 W/cm3 is significantly lower than for magnetic transformers with the same voltage and power output. This development, which is being done under a Small Business Innovation Research (SBIR) contract by Face Electronics, LC (Norfolk, VA), is based on improvements in the materials and design of Face's basic patented Transoner-T3 PT, shown in the left in the following figure. The T3 PT is most simply described as a resonant multilayer transducer where electrical energy at the input section is efficiently mechanically coupled to the output section, which then vibrates in a fundamental longitudinal mode to generate a high gain in voltage. The piezoelectric material used is a modified lead-zirconium-titanate-based ceramic. One of the significant improvements in PT design was the incorporation of a symmetrical double input layer, shown on the right in the following figure, which eliminated the lossy bending vibration modes characteristic of a single input layer. The performance of the improved PT was optimized to 1.5 kV/5 W. The next step was devising a way to combine the individual PTs in a modular circuit topology needed to achieve the desired high voltage and power output. Since the optimum performance of the individual PT occurs at resonance, the most efficient operation of the modular transformer was achieved by using a separate drive circuit for each PT. The output section consists of a separate output rectifier for each PT connected in series.

Underwater thrust and power generation using flexible piezoelectric composites: an experimental investigation toward self-powered swimmer-sensor platforms

NASA Astrophysics Data System (ADS)

Erturk, Alper; Delporte, Ghislain

2011-12-01

Fiber-based flexible piezoelectric composites offer several advantages to use in energy harvesting and biomimetic locomotion. These advantages include ease of application, high power density, effective bending actuation, silent operation over a range of frequencies, and light weight. Piezoelectric materials exhibit the well-known direct and converse piezoelectric effects. The direct piezoelectric effect has received growing attention for low-power generation to use in wireless electronic applications while the converse piezoelectric effect constitutes an alternative to replace the conventional actuators used in biomimetic locomotion. In this paper, underwater thrust and electricity generation are investigated experimentally by focusing on biomimetic structures with macro-fiber composite piezoelectrics. Fish-like bimorph configurations with and without a passive caudal fin (tail) are fabricated and compared. The favorable effect of having a passive caudal fin on the frequency bandwidth is reported. The presence of a passive caudal fin is observed to bring the second bending mode close to the first one, yielding a wideband behavior in thrust generation. The same smart fish configuration is tested for underwater piezoelectric power generation in response to harmonic excitation from its head. Resonant piezohydroelastic actuation is reported to generate milli-newton level hydrodynamic thrust using milli-watt level actuation power input. The average actuation power requirement for generating a mean thrust of 19 mN at 6 Hz using a 10 g piezoelastic fish with a caudal fin is measured as 120 mW. This work also discusses the feasibility of thrust generation using the harvested energy toward enabling self-powered swimmer-sensor platforms with comparisons based on the capacity levels of structural thin-film battery layers as well as harvested solar and vibrational energy.

Understanding GPU Power. A Survey of Profiling, Modeling, and Simulation Methods

DOE PAGES

Bridges, Robert A.; Imam, Neena; Mintz, Tiffany M.

2016-09-01

Modern graphics processing units (GPUs) have complex architectures that admit exceptional performance and energy efficiency for high throughput applications.Though GPUs consume large amounts of power, their use for high throughput applications facilitate state-of-the-art energy efficiency and performance. Consequently, continued development relies on understanding their power consumption. Our work is a survey of GPU power modeling and profiling methods with increased detail on noteworthy efforts. Moreover, as direct measurement of GPU power is necessary for model evaluation and parameter initiation, internal and external power sensors are discussed. Hardware counters, which are low-level tallies of hardware events, share strong correlation to powermore » use and performance. Statistical correlation between power and performance counters has yielded worthwhile GPU power models, yet the complexity inherent to GPU architectures presents new hurdles for power modeling. Developments and challenges of counter-based GPU power modeling is discussed. Often building on the counter-based models, research efforts for GPU power simulation, which make power predictions from input code and hardware knowledge, provide opportunities for optimization in programming or architectural design. Noteworthy strides in power simulations for GPUs are included along with their performance or functional simulator counterparts when appropriate. Lastly, possible directions for future research are discussed.« less

Understanding GPU Power. A Survey of Profiling, Modeling, and Simulation Methods

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

Bridges, Robert A.; Imam, Neena; Mintz, Tiffany M.

Modern graphics processing units (GPUs) have complex architectures that admit exceptional performance and energy efficiency for high throughput applications.Though GPUs consume large amounts of power, their use for high throughput applications facilitate state-of-the-art energy efficiency and performance. Consequently, continued development relies on understanding their power consumption. Our work is a survey of GPU power modeling and profiling methods with increased detail on noteworthy efforts. Moreover, as direct measurement of GPU power is necessary for model evaluation and parameter initiation, internal and external power sensors are discussed. Hardware counters, which are low-level tallies of hardware events, share strong correlation to powermore » use and performance. Statistical correlation between power and performance counters has yielded worthwhile GPU power models, yet the complexity inherent to GPU architectures presents new hurdles for power modeling. Developments and challenges of counter-based GPU power modeling is discussed. Often building on the counter-based models, research efforts for GPU power simulation, which make power predictions from input code and hardware knowledge, provide opportunities for optimization in programming or architectural design. Noteworthy strides in power simulations for GPUs are included along with their performance or functional simulator counterparts when appropriate. Lastly, possible directions for future research are discussed.« less

Environmental Loss Characterization of an Advanced Stirling Convertor (ASC-E2) Insulation Package Using a Mock Heater Head

NASA Technical Reports Server (NTRS)

Schifer, Nicholas A.; Briggs, Maxwell H.

2012-01-01

The U.S. Department of Energy (DOE) and Lockheed Martin Space Systems Company (LMSSC) have been developing the Advanced Stirling Radioisotope Generator (ASRG) for use as a power system for space science missions. This generator would use two highefficiency Advanced Stirling Convertors (ASCs), developed by Sunpower Inc. and NASA Glenn Research Center (GRC). As part of ground testing of these ASCs, different operating conditions are used to simulate expected mission conditions. These conditions require achieving a specified electrical power output for a given net heat input. While electrical power output can be precisely quantified, thermal power input to the Stirling cycle cannot be directly measured. In an effort to improve net heat input predictions, the Mock Heater Head was developed with the same relative thermal paths as a convertor using a conducting rod to represent the Stirling cycle and tested to provide a direct comparison to numerical and empirical models used to predict convertor net heat input. The Mock Heater Head also served as the pathfinder for a higher fidelity version of validation test hardware, known as the Thermal Standard. This paper describes how the Mock Heater Head was tested and utilized to validate a process for the Thermal Standard.

Sympathovagal imbalance in hyperthyroidism.

PubMed

Burggraaf, J; Tulen, J H; Lalezari, S; Schoemaker, R C; De Meyer, P H; Meinders, A E; Cohen, A F; Pijl, H

2001-07-01

We assessed sympathovagal balance in thyrotoxicosis. Fourteen patients with Graves' hyperthyroidism were studied before and after 7 days of treatment with propranolol (40 mg 3 times a day) and in the euthyroid state. Data were compared with those obtained in a group of age-, sex-, and weight-matched controls. Autonomic inputs to the heart were assessed by power spectral analysis of heart rate variability. Systemic exposure to sympathetic neurohormones was estimated on the basis of 24-h urinary catecholamine excretion. The spectral power in the high-frequency domain was considerably reduced in hyperthyroid patients, indicating diminished vagal inputs to the heart. Increased heart rate and mid-frequency/high-frequency power ratio in the presence of reduced total spectral power and increased urinary catecholamine excretion strongly suggest enhanced sympathetic inputs in thyrotoxicosis. All abnormal features of autonomic balance were completely restored to normal in the euthyroid state. beta-Adrenoceptor antagonism reduced heart rate in hyperthyroid patients but did not significantly affect heart rate variability or catecholamine excretion. This is in keeping with the concept of a joint disruption of sympathetic and vagal inputs to the heart underlying changes in heart rate variability. Thus thyrotoxicosis is characterized by profound sympathovagal imbalance, brought about by increased sympathetic activity in the presence of diminished vagal tone.

Bi-directional power control system for voltage converter

DOEpatents

Garrigan, Neil Richard; King, Robert Dean; Schwartz, James Edward

1999-01-01

A control system for a voltage converter includes: a power comparator for comparing a power signal on input terminals of the converter with a commanded power signal and producing a power comparison signal; a power regulator for transforming the power comparison signal to a commanded current signal; a current comparator for comparing the commanded current signal with a measured current signal on output terminals of the converter and producing a current comparison signal; a current regulator for transforming the current comparison signal to a pulse width modulator (PWM) duty cycle command signal; and a PWM for using the PWM duty cycle command signal to control electrical switches of the converter. The control system may further include: a command multiplier for converting a voltage signal across the output terminals of the converter to a gain signal having a value between zero (0) and unity (1), and a power multiplier for multiplying the commanded power signal by the gain signal to provide a limited commanded power signal, wherein power comparator compares the limited commanded power signal with the power signal on the input terminals.

Bi-directional power control system for voltage converter

DOEpatents

Garrigan, N.R.; King, R.D.; Schwartz, J.E.

1999-05-11

A control system for a voltage converter includes: a power comparator for comparing a power signal on input terminals of the converter with a commanded power signal and producing a power comparison signal; a power regulator for transforming the power comparison signal to a commanded current signal; a current comparator for comparing the commanded current signal with a measured current signal on output terminals of the converter and producing a current comparison signal; a current regulator for transforming the current comparison signal to a pulse width modulator (PWM) duty cycle command signal; and a PWM for using the PWM duty cycle command signal to control electrical switches of the converter. The control system may further include: a command multiplier for converting a voltage signal across the output terminals of the converter to a gain signal having a value between zero (0) and unity (1), and a power multiplier for multiplying the commanded power signal by the gain signal to provide a limited commanded power signal, wherein power comparator compares the limited commanded power signal with the power signal on the input terminals. 10 figs.

Design, fabrication and testing of a CFA for use in the solar power satellite

NASA Technical Reports Server (NTRS)

Brown, W. C.

1978-01-01

A crossed field amplifier was designed to meet the performance objectives of high signal to noise ratio, an efficiency of 85%, a CW microwave power output of 5-8 kW, and a frequency of 2450 MHz. The signal to noise ratio achieved was better than 69 db/MHz in a 2000 MHz band centered on the carrier. High circuit efficiency of 97% and a sharp knee on voltage current characteristic were achieved. The basic problem of maintaining good transfer of heat to the external radiator while providing for adequate connections to input and output was solved. Maximum efficiency achieved was 70.5% and gain and power level were below objectives. An investigation of causes of reduced performance indicated the poor field pattern in the cathode anode interaction area of the tube was a major cause.

Bolometer Results in the Long-Microwave-Heated WEGA Stellarator

NASA Astrophysics Data System (ADS)

Zhang, D.; Otte, M.; Giannone, L.

2006-01-01

A 12 channel bolometer camera based on a gold foil absorber has been installed on the WEGA stellarator to measure the radiation power losses of the plasma. The measured total radiation power is typically less than 30% of the ECRH input power. However, this radiated power fraction depends on the ECRH input power, the magnetic configuration and the field strength as well as the working gas. For separatrix-bounded configurations, core-peaked radiation intensity profiles are usually detected, while in a limiter-configuration they are flatter, broader and more asymmetric. In addition, significant radiation originating from the SOL region is measured for all the cases studied. The SOL radiation changes with changing the plasma-wave interaction region, indicating a strong correlation between radiation and power deposition. Under the WEGA-plasma conditions (Te<10 eV), it is considered that the radiation profile reflects the plasma pressure associated with the power deposition distribution of the ECRH.

Constant Switching Frequency DTC for Matrix Converter Fed Speed Sensorless Induction Motor Drive

NASA Astrophysics Data System (ADS)

Mir, Tabish Nazir; Singh, Bhim; Bhat, Abdul Hamid

2018-05-01

The paper presents a constant switching frequency scheme for speed sensorless Direct Torque Control (DTC) of Matrix Converter fed Induction Motor Drive. The use of matrix converter facilitates improved power quality on input as well as motor side, along with Input Power Factor control, besides eliminating the need for heavy passive elements. Moreover, DTC through Space Vector Modulation helps in achieving a fast control over the torque and flux of the motor, with added benefit of constant switching frequency. A constant switching frequency aids in maintaining desired power quality of AC mains current even at low motor speeds, and simplifies input filter design of the matrix converter, as compared to conventional hysteresis based DTC. Further, stator voltage estimation from sensed input voltage, and subsequent stator (and rotor) flux estimation is done. For speed sensorless operation, a Model Reference Adaptive System is used, which emulates the speed dependent rotor flux equations of the induction motor. The error between conventionally estimated rotor flux (reference model) and the rotor flux estimated through the adaptive observer is processed through PI controller to generate the rotor speed estimate.

Low reflectance high power RF load

DOEpatents

Ives, R. Lawrence; Mizuhara, Yosuke M.

2016-02-02

A load for traveling microwave energy has an absorptive volume defined by cylindrical body enclosed by a first end cap and a second end cap. The first end cap has an aperture for the passage of an input waveguide with a rotating part that is coupled to a reflective mirror. The inner surfaces of the absorptive volume consist of a resistive material or are coated with a coating which absorbs a fraction of incident RF energy, and the remainder of the RF energy reflects. The angle of the reflector and end caps is selected such that reflected RF energy dissipates an increasing percentage of the remaining RF energy at each reflection, and the reflected RF energy which returns to the rotating mirror is directed to the back surface of the rotating reflector, and is not coupled to the input waveguide. Additionally, the reflector may have a surface which generates a more uniform power distribution function axially and laterally, to increase the power handling capability of the RF load. The input waveguide may be corrugated for HE11 mode input energy.

Renewable Electrolysis | Hydrogen and Fuel Cells | NREL

Science.gov Websites

variable-input power conditions Designing and developing shared power-electronics packages and controllers Development NREL develops power electronics interfaces for renewable electrolysis systems to characterize and constant voltage DC bus and power electronics to regulate power output and to convert wild alternating

47 CFR 80.859 - Main power supply.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 5 2010-10-01 2010-10-01 false Main power supply. 80.859 Section 80.859... power supply. (a) The main power supply must simultaneously energize the radiotelephone transmitter at... main power supply at the radiotelephone input terminals must not deviate from its rated potential by...

47 CFR 80.859 - Main power supply.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 5 2011-10-01 2011-10-01 false Main power supply. 80.859 Section 80.859... power supply. (a) The main power supply must simultaneously energize the radiotelephone transmitter at... main power supply at the radiotelephone input terminals must not deviate from its rated potential by...

Waveguide Power Combiner Demonstration for Multiple High Power Millimeter Wave TWTAs

NASA Technical Reports Server (NTRS)

Wintucky, Edwin G.; Simons, Rainee N.; Lesny, Gary G.; Glass, Jeffrey L.

2004-01-01

NASA is presently developing nuclear reactor technologies, under Project Prometheus, which will provide spacecraft with greatly increased levels of sustained onboard power and thereby dramatically enhance the capability for future deep space exploration. The first mission planned for use of this high power technology is the Jupiter Icy Moons Orbiter (JIMO). In addition to electric propulsion and science, there will also be unprecedented onboard power available for deep space communications. A 32 GHz transmitter with 1 kW of RF output power is being considered to enable the required very high data transmission rates. One approach to achieving the 1 kW RF power, now being investigated at NASA GRC, is the possible power combining of a number of 100-1 50 W TWTs now under development. The work presented here is the results of a proof-of-concept demonstration of the power combining Ka-band waveguide circuit design and test procedure using two Ka- band TWTAs (Varian model VZA6902V3 and Logimetrics model A440/KA-1066), both of which were previously employed in data uplink evaluation terminals at 29.36 GHz for the NASA Advanced Communications Technology Satellite (ACTS) program. The characterization of the individual TWTAs and power combining demonstration were done over a 500 MHz bandwidth from 29.1 to 29.6 GHz to simulate the Deep Space Network (DSN) bandwidth of 3 1.8 to 32.3 GHz. Figures 1-3 show some of the power transfer and gain measurements of the TWTAs using a swept signal generator (Agilent 83640b) for the RF input. The input and output powers were corrected for circuit insertion losses due to the waveguide components. The RF saturated powers of both ACTS TWTAs were on the order of 120 W, which is comparable to the expected output powers of the 32 GHz TWTs. Additional results for the individual TWTAs will be presented (AM/AM, AM/PM conversion and gain compression), some of which were obtained from swept frequency and power measurements using a vector network analyzer. The results for the power combining demonstration as well as a more detailed description of the power combining test circuit and test procedure will also be presented.

High Efficiency Ka-Band Solid State Power Amplifier Waveguide Power Combiner

NASA Technical Reports Server (NTRS)

Wintucky, Edwin G.; Simons, Rainee N.; Chevalier, Christine T.; Freeman, Jon C.

2010-01-01

A novel Ka-band high efficiency asymmetric waveguide four-port combiner for coherent combining of two Monolithic Microwave Integrated Circuit (MMIC) Solid State Power Amplifiers (SSPAs) having unequal outputs has been successfully designed, fabricated and characterized over the NASA deep space frequency band from 31.8 to 32.3 GHz. The measured combiner efficiency is greater than 90 percent, the return loss greater than 18 dB and input port isolation greater than 22 dB. The manufactured combiner was designed for an input power ratio of 2:1 but can be custom designed for any arbitrary power ratio. Applications considered are NASA s space communications systems needing 6 to 10 W of radio frequency (RF) power. This Technical Memorandum (TM) is an expanded version of the article recently published in Institute of Engineering and Technology (IET) Electronics Letters.

Operational trends in the temperature of a high-pressure microwave powered sulfur lamp

NASA Astrophysics Data System (ADS)

Johnston, C. W.; Jonkers, J.; van der Mullen, J. J. A. M.

2002-10-01

Temperatures have been measured in a high-pressure microwave sulfur lamp using sulfur atomic lines found in the spectrum at 867, 921 and 1045 nm. The absolute intensities were determined for 3, 5 and 7 bar lamps at several input powers, ranging from 400 to 600 W. On average, temperatures are found to be 4.1+/-0.15 kK and increase slightly with increasing pressure and input power. These values and trends agree well with our simulations. However, the power trend is reversed to that demonstrated by the model, which might be an indication that the skin-depth model for the electric field may be incomplete.

Reconstructed Sediment Mobilization Processes in a Large Reservoir Using Short Sediment Cores

NASA Astrophysics Data System (ADS)

Cockburn, J.; Feist, S.

2014-12-01

Williston Reservoir in northern British Columbia (56°10'31"N, 124°06'33") was formed when the W.A.C. Bennett Dam was created in the late 1960s, is the largest inland body of water in BC and facilitates hydroelectric power generation. Annually the reservoir level rises and lowers with the hydroelectric dam operation, and this combined with the inputs from several river systems (Upper Peace, Finlay, Parsnip, and several smaller creeks) renews suspended sediment sources. Several short-cores retrieved from shallow bays of the Finlay Basin reveal near-annual sedimentary units and distinct patterns related to both hydroclimate variability and the degree to which the reservoir lowered in a particular year. Thin section and sedimentology from short-cores collected in three bays are used to evaluate sediment mobilization processes. The primary sediment sources in each core location is linked to physical inputs from rivers draining into the bays, aeolian contributions, and reworked shoreline deposits as water levels fluctuate. Despite uniform water level lowering across the reservoir, sediment sequences differed at each site, reflecting the local stream inputs. However, distinct organic-rich units, facilitated correlation across the sites. Notable differences in particle size distributions from each core points to important aeolian derived sediment sources. Using these sedimentary records, we can evaluate the processes that contribute to sediment deposition in the basin. This work will contribute to decisions regarding reservoir water levels to reduce adverse impacts on health, economic activities and recreation in the communities along the shores of the reservoir.

Glutamate-Bound NMDARs Arising from In Vivo-like Network Activity Extend Spatio-temporal Integration in a L5 Cortical Pyramidal Cell Model

PubMed Central

Farinella, Matteo; Ruedt, Daniel T.; Gleeson, Padraig; Lanore, Frederic; Silver, R. Angus

2014-01-01

In vivo, cortical pyramidal cells are bombarded by asynchronous synaptic input arising from ongoing network activity. However, little is known about how such ‘background’ synaptic input interacts with nonlinear dendritic mechanisms. We have modified an existing model of a layer 5 (L5) pyramidal cell to explore how dendritic integration in the apical dendritic tuft could be altered by the levels of network activity observed in vivo. Here we show that asynchronous background excitatory input increases neuronal gain and extends both temporal and spatial integration of stimulus-evoked synaptic input onto the dendritic tuft. Addition of fast and slow inhibitory synaptic conductances, with properties similar to those from dendritic targeting interneurons, that provided a ‘balanced’ background configuration, partially counteracted these effects, suggesting that inhibition can tune spatio-temporal integration in the tuft. Excitatory background input lowered the threshold for NMDA receptor-mediated dendritic spikes, extended their duration and increased the probability of additional regenerative events occurring in neighbouring branches. These effects were also observed in a passive model where all the non-synaptic voltage-gated conductances were removed. Our results show that glutamate-bound NMDA receptors arising from ongoing network activity can provide a powerful spatially distributed nonlinear dendritic conductance. This may enable L5 pyramidal cells to change their integrative properties as a function of local network activity, potentially allowing both clustered and spatially distributed synaptic inputs to be integrated over extended timescales. PMID:24763087

Analytical and experimental comparisons of electromechanical vibration response of a piezoelectric bimorph beam for power harvesting

NASA Astrophysics Data System (ADS)

Lumentut, M. F.; Howard, I. M.

2013-03-01

Power harvesters that extract energy from vibrating systems via piezoelectric transduction show strong potential for powering smart wireless sensor devices in applications of health condition monitoring of rotating machinery and structures. This paper presents an analytical method for modelling an electromechanical piezoelectric bimorph beam with tip mass under two input base transverse and longitudinal excitations. The Euler-Bernoulli beam equations were used to model the piezoelectric bimorph beam. The polarity-electric field of the piezoelectric element is excited by the strain field caused by base input excitation, resulting in electrical charge. The governing electromechanical dynamic equations were derived analytically using the weak form of the Hamiltonian principle to obtain the constitutive equations. Three constitutive electromechanical dynamic equations based on independent coefficients of virtual displacement vectors were formulated and then further modelled using the normalised Ritz eigenfunction series. The electromechanical formulations include both the series and parallel connections of the piezoelectric bimorph. The multi-mode frequency response functions (FRFs) under varying electrical load resistance were formulated using Laplace transformation for the multi-input mechanical vibrations to provide the multi-output dynamic displacement, velocity, voltage, current and power. The experimental and theoretical validations reduced for the single mode system were shown to provide reasonable predictions. The model results from polar base excitation for off-axis input motions were validated with experimental results showing the change to the electrical power frequency response amplitude as a function of excitation angle, with relevance for practical implementation.

Flexible power and bandwidth allocation in mobile satellites

NASA Astrophysics Data System (ADS)

Keyes, L. A.

The introduction of L-band mobile communication services by spot beam satellites creates a payload design challenge due to uncertainty in the location and size of the new market to be served. A combination of payload technologies that allow a flexible allocation of power and bandwidth to any portion of the coverage area is described. Power flexibility is achieved by a novel combination of a low-level beam-forming network and a matrix power module which ensures equal sharing of power among individual amplifiers. This eliminates the loss of efficiency and increased mass when an amplifier associated with a beam must be over-designed to meet uncertainties in power distribution between beams. Flexibility in allocation of bandwidth to beams is achieved by intermediate frequency subdivision of the L-band service categories defined by ITU. These spectral subdivisions are assigned to beams by an IF interconnect matrix having beam ports and filter ports as inputs and outputs, respectively. Two such filter switch matrices are required, one for the inbound L-band to feeder link transponder, and one for the outbound feeder link to L-band transponder.

47 CFR 80.915 - Main power supply.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 5 2010-10-01 2010-10-01 false Main power supply. 80.915 Section 80.915... supply. (a) There must be readily available for use under normal load conditions a main power supply... required receiver. Under this load condition the potential of the main power supply at the power input...

47 CFR 80.915 - Main power supply.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 5 2011-10-01 2011-10-01 false Main power supply. 80.915 Section 80.915... supply. (a) There must be readily available for use under normal load conditions a main power supply... required receiver. Under this load condition the potential of the main power supply at the power input...

Potential Damage to Flight Hardware from MIL-STD-462 CS02 Setup

NASA Technical Reports Server (NTRS)

Harris, Patrick K.; Block, Nathan F.

2003-01-01

The MIL-STD-462 CS02 conducted susceptibility test setup includes an audio transformer, with the secondary used as an inductor, and a large capacitor. Together, these two components form an L-type low-pass filter to minimize the injected test signal input into the power source. Some flight hardware power input configurations are not compatible with this setup and break into oscillation when powered up. This, in turn, can damage flight hardware. Such an oscillation resulted in the catastrophic failure of an item tested in the Goddard Space Flight Center (GSFC) Large electromagnetic compatibility (EMC) Test Facility.

Potential Damage to Flight Hardware from MIL-STD-462 CS02 Setup

NASA Technical Reports Server (NTRS)

Harris, Patrick K.; Block, Nathan F.

2002-01-01

The MIL-STD-462 CS02 conducted susceptibility test setup, performed during electromagnetic compatibility (EMC) testing, consists of an audio transformer with the secondary used as an inductor and a large capacitor. Together, these two components form an L-type low-pass filter to minimize the injected test signal input into the power source. Some flight hardware power input configurations are not compatible with this setup and break into oscillation when powered up. This can damage flight hardware and caused a catastrophic failure to an item tested in the Goddard Space Flight Center (GSFC) Large EMC Test Facility.

Optimizing pulsed Nd:YAG laser beam welding process parameters to attain maximum ultimate tensile strength for thin AISI316L sheet using response surface methodology and simulated annealing algorithm

NASA Astrophysics Data System (ADS)

Torabi, Amir; Kolahan, Farhad

2018-07-01

Pulsed laser welding is a powerful technique especially suitable for joining thin sheet metals. In this study, based on experimental data, pulsed laser welding of thin AISI316L austenitic stainless steel sheet has been modeled and optimized. The experimental data required for modeling are gathered as per Central Composite Design matrix in Response Surface Methodology (RSM) with full replication of 31 runs. Ultimate Tensile Strength (UTS) is considered as the main quality measure in laser welding. Furthermore, the important process parameters including peak power, pulse duration, pulse frequency and welding speed are selected as input process parameters. The relation between input parameters and the output response is established via full quadratic response surface regression with confidence level of 95%. The adequacy of the regression model was verified using Analysis of Variance technique results. The main effects of each factor and the interactions effects with other factors were analyzed graphically in contour and surface plot. Next, to maximum joint UTS, the best combinations of parameters levels were specified using RSM. Moreover, the mathematical model is implanted into a Simulated Annealing (SA) optimization algorithm to determine the optimal values of process parameters. The results obtained by both SA and RSM optimization techniques are in good agreement. The optimal parameters settings for peak power of 1800 W, pulse duration of 4.5 ms, frequency of 4.2 Hz and welding speed of 0.5 mm/s would result in a welded joint with 96% of the base metal UTS. Computational results clearly demonstrate that the proposed modeling and optimization procedures perform quite well for pulsed laser welding process.

Energy prices and substitution in United States manufacturing plants

NASA Astrophysics Data System (ADS)

Grim, Cheryl

Persistent regional disparities in electricity prices, growth in wholesale power markets, and recent deregulation attempts have intensified interest in the performance of the U.S. electric power industry, while skyrocketing fuel prices have brought renewed interest in the effect of changes in prices of all energy types on the U.S. economy. This dissertation examines energy prices and substitution between energy types in U.S. manufacturing. I use a newly constructed database that includes information on purchased electricity and electricity expenditures for more than 48,000 plants per year and additional data on the utilities that supply electricity to study the distribution of electricity prices paid by U.S. manufacturing plants from 1963 to 2000. I find a large compression in the dispersion of electricity prices from 1963 to 1978 due primarily to a decrease in quantity discounts for large electricity purchasers. I also find that spatial dispersion in retail electricity prices among states, counties and utility service territories is large, rises over time for smaller purchasers, and does not diminish as wholesale power markets expand in the 1990s. In addition, I examine energy type consumption patterns, prices, and substitution in U.S. manufacturing plants. I develop a plant-level dataset for 1998 with data on consumption and expenditures on energy and non-energy production inputs, output, and other plant characteristics. I find energy type consumption patterns vary widely across manufacturing plants. Further, I find a large amount of dispersion across plants in the prices paid for electricity, oil, natural gas, and coal. These high levels of dispersion are accounted for by the plant's location, industry, and purchase quantity. Finally, I present estimates of own- and cross-price elasticities of demand for both the energy and non-energy production inputs.

Equations For Rotary Transformers

NASA Technical Reports Server (NTRS)

Salomon, Phil M.; Wiktor, Peter J.; Marchetto, Carl A.

1988-01-01

Equations derived for input impedance, input power, and ratio of secondary current to primary current of rotary transformer. Used for quick analysis of transformer designs. Circuit model commonly used in textbooks on theory of ac circuits.

Evaluation of Advanced Stirling Convertor Net Heat Input Correlation Methods Using a Thermal Standard

NASA Technical Reports Server (NTRS)

Briggs, Maxwell H.; Schifer, Nicholas A.

2012-01-01

The U.S. Department of Energy (DOE) and Lockheed Martin Space Systems Company (LMSSC) have been developing the Advanced Stirling Radioisotope Generator (ASRG) for use as a power system for space science missions. This generator would use two high-efficiency Advanced Stirling Convertors (ASCs), developed by Sunpower Inc. and NASA Glenn Research Center (GRC). The ASCs convert thermal energy from a radioisotope heat source into electricity. As part of ground testing of these ASCs, different operating conditions are used to simulate expected mission conditions. These conditions require achieving a particular operating frequency, hot end and cold end temperatures, and specified electrical power output for a given net heat input. In an effort to improve net heat input predictions, numerous tasks have been performed which provided a more accurate value for net heat input into the ASCs, including testing validation hardware, known as the Thermal Standard, to provide a direct comparison to numerical and empirical models used to predict convertor net heat input. This validation hardware provided a comparison for scrutinizing and improving empirical correlations and numerical models of ASC-E2 net heat input. This hardware simulated the characteristics of an ASC-E2 convertor in both an operating and non-operating mode. This paper describes the Thermal Standard testing and the conclusions of the validation effort applied to the empirical correlation methods used by the Radioisotope Power System (RPS) team at NASA Glenn.

Fission Surface Power Systems (FSPS) Project Final Report for the Exploration Technology Development Program (ETDP): Fission Surface Power, Transition Face to Face

NASA Technical Reports Server (NTRS)

Palac, Donald T.

2011-01-01

The Fission Surface Power Systems Project became part of the ETDP on October 1, 2008. Its goal was to demonstrate fission power system technology readiness in an operationally relevant environment, while providing data on fission system characteristics pertinent to the use of a fission power system on planetary surfaces. During fiscal years 08 to 10, the FSPS project activities were dominated by hardware demonstrations of component technologies, to verify their readiness for inclusion in the fission surface power system. These Pathfinders demonstrated multi-kWe Stirling power conversion operating with heat delivered via liquid metal NaK, composite Ti/H2O heat pipe radiator panel operations at 400 K input water temperature, no-moving-part electromagnetic liquid metal pump operation with NaK at flight-like temperatures, and subscale performance of an electric resistance reactor simulator capable of reproducing characteristics of a nuclear reactor for the purpose of system-level testing, and a longer list of component technologies included in the attached report. Based on the successful conclusion of Pathfinder testing, work began in 2010 on design and development of the Technology Demonstration Unit (TDU), a full-scale 1/4 power system-level non-nuclear assembly of a reactor simulator, power conversion, heat rejection, instrumentation and controls, and power management and distribution. The TDU will be developed and fabricated during fiscal years 11 and 12, culminating in initial testing with water cooling replacing the heat rejection system in 2012, and complete testing of the full TDU by the end of 2014. Due to its importance for Mars exploration, potential applicability to missions preceding Mars missions, and readiness for an early system-level demonstration, the Enabling Technology Development and Demonstration program is currently planning to continue the project as the Fission Power Systems project, including emphasis on the TDU completion and testing.

Third order intermodulation distortion in HTS Josephson Junction downconverter at 12GHz

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

Suzuki, Katsumi; Hayashi, Kunihiko; Fujimoto, Manabu

1994-12-31

Here the authors first report on the microwave characteristics of the third order intermodulation distortion(IMD3) in High-Tc Superconductor (HTS) Josephson Junction (JJ) Downconverter at 12GHz. They have successfully developed high quality nonlinear YBCO microbridge Josephson junctions for such an active MMIC as a mixer with RF, LO, IF and bias filters, which have been fabricated on (100) MgO substrates with 20mm x 20mm x 0.5mm dimensions. The minimum conversion loss of the JJ mixer is 11 dB at very small local microwave input power LO= {minus}20dBm which is two order less than Schottky diode mixer. Consequently, this small optimum LOmore » power gives the small RF input power at which the output IF power of the YBCO mixer saturates. Two-tone third-order intercept point(IP3) performance is a significantly important figure of merit typically used to define linearity of devices and circuits. The RF input power = {minus}15dBm at the IP3 point is obtained for the YBCO mixer at 15K and LO = 10.935GHz with {minus}22dBm. The have successfully measured the dependence of IMD3 on temperature, bias current and LO power.« less

Analysis of the power flow in nonlinear oscillators driven by random excitation using the first Wiener kernel

NASA Astrophysics Data System (ADS)

Hawes, D. H.; Langley, R. S.

2018-01-01

Random excitation of mechanical systems occurs in a wide variety of structures and, in some applications, calculation of the power dissipated by such a system will be of interest. In this paper, using the Wiener series, a general methodology is developed for calculating the power dissipated by a general nonlinear multi-degree-of freedom oscillatory system excited by random Gaussian base motion of any spectrum. The Wiener series method is most commonly applied to systems with white noise inputs, but can be extended to encompass a general non-white input. From the extended series a simple expression for the power dissipated can be derived in terms of the first term, or kernel, of the series and the spectrum of the input. Calculation of the first kernel can be performed either via numerical simulations or from experimental data and a useful property of the kernel, namely that the integral over its frequency domain representation is proportional to the oscillating mass, is derived. The resulting equations offer a simple conceptual analysis of the power flow in nonlinear randomly excited systems and hence assist the design of any system where power dissipation is a consideration. The results are validated both numerically and experimentally using a base-excited cantilever beam with a nonlinear restoring force produced by magnets.

Power play in the supercontinuum spectra of saturable nonlinear media

NASA Astrophysics Data System (ADS)

Nithyanandan, K.; Vasantha Jayakantha Raja, R.; Porsezian, K.

2014-04-01

We investigate the role of pump power in the generation of supercontinua spectra induced by modulational instability (MI) in saturable nonlinear media (SNL). First, we analyze the dynamics of MI in the SNL using linear stability analysis. We then deal with the generation of a broadband spectrum by virtue of the instability process, and identify the unique behavior of MI in the SNL system. Unlike the case of Kerr-type nonlinearity, the so-called critical modulational frequency (CMF) does not monotonically increase, but behaves in a unique way, such that the increase in power increases the CMF up to the saturation power, and a further increase in power decreases the CMF. This behavior is identified to be unusual in the context of MI and thus makes the study of MI and supercontinuum generation (SCG) of interest. In order to confirm the above stated behavior in relation to SCG, we numerically analyzed the SCG using a split-step Fourier method, and the results confirm that at input power equal to saturation power, phase matching occurs at a short distance relative to other power levels and leads to a maximum enhancement of SCG in certain SNL materials.

Programmable differential capacitance-to-voltage converter for MEMS accelerometers

NASA Astrophysics Data System (ADS)

Royo, G.; Sánchez-Azqueta, C.; Gimeno, C.; Aldea, C.; Celma, S.

2017-05-01

Capacitive MEMS sensors exhibit an excellent noise performance, high sensitivity and low power consumption. They offer a huge range of applications, being the accelerometer one of its main uses. In this work, we present the design of a capacitance-to-voltage converter in CMOS technology to measure the acceleration from the capacitance variations. It is based on a low-power, fully-differential transimpedance amplifier with low input impedance and a very low input noise.

47 CFR 25.212 - Narrowband analog transmissions and digital transmissions in the GSO Fixed Satellite Service.

Code of Federal Regulations, 2013 CFR

2013-10-01

... kHz if the maximum input power spectral density into the antenna does not exceed −8 dBW/4 kHz and the maximum transmitted satellite carrier EIRP density does not exceed 17 dBW/4 kHz. (2) In the 14.0... services, if the maximum input spectral power density into the antenna does not exceed −14 dBW/4 kHz, and...

Electromagnetic interference filter for automotive electrical systems

DOEpatents

Herron, Nicholas Hayden; Carlson, Douglas S; Tang, David; Korich, Mark D

2013-07-02

A filter for an automotive electrical system includes a substrate having first and second conductive members. First and second input terminals are mounted to the substrate. The first input terminal is electrically connected to the first conductive member, and the second input terminal is electrically connected to the second conductive member. A plurality of capacitors are mounted to the substrate. Each of the capacitors is electrically connected to at least one of the first and second conductive members. First and second power connectors are mounted to the substrate. The first power connector is electrically connected to the first conductive member, and the second power connector is electrically connected to the second conductive member. A common mode choke is coupled to the substrate and arranged such that the common mode choke extends around at least a portion of the substrate and the first and second conductive members.

Chlorine incorporation in silicon films deposited by low-pressure rf discharges in gas mixtures of SICL/sub 4/ + H/sup 2/ + AR

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

Manory, R; Auni, R; Grill, A

1984-12-01

Silicon films were deposited from tetrachlorosilane by its dissociation in argon and hydrogen rf plasma at a pressure of 2 Torr. The concentration of chlorine incorporated in the films was found to be dependent on the macrovariables of the plasma such as power input and substrate position in the plasma reactor. Mass spectrometric measurements of the plasma showed that the concentration of HCI in the plasma was strongly dependent on the power input and on position in the plasma along the gas stream. At high input powers the HCI formed in the plasma dissociates to free radicals, contributing to amore » recombination process in the gas phase and codeposition with silicon on the substrate. The correlation between the HCI reactions in the plasma and the incorporation of CL in the deposit is shown.« less

Mode control in a high-gain relativistic klystron amplifier

NASA Astrophysics Data System (ADS)

Li, Zheng-Hong; Zhang, Hong; Ju, Bing-Quan; Su, Chang; Wu, Yang

2010-05-01

Middle cavities between the input and output cavity can be used to decrease the required input RF power for the relativistic klystron amplifier. Meanwhile higher modes, which affect the working mode, are also easy to excite in a device with more middle cavities. In order for the positive feedback process for higher modes to be excited, a special measure is taken to increase the threshold current for such modes. Higher modes' excitation will be avoided when the threshold current is significantly larger than the beam current. So a high-gain S-band relativistic klystron amplifier is designed for the beam of current 5 kA and beam voltage 600 kV. Particle in cell simulations show that the gain is 1.6 × 105 with the input RF power of 6.8 kW, and that the output RF power reaches 1.1 GW.

High efficiency 40 K single-stage Stirling-type pulse tube cryocooler

NASA Astrophysics Data System (ADS)

Wu, X. L.; Chen, L. B.; Pan, C. Z.; Cui, C.; Wang, J. J.; Zhou, Y.

2017-12-01

A high efficiency single-stage Stirling-type coaxial pulse tube cryocooler (SPTC) operating at around 40 K has been designed, built and tested. The double-inlet and the inertance tubes together with the gas reservoir were adopted as the phase shifters. Under the conditions of 2.5 MPa charging pressure and 30 Hz operating frequency, the prototype has achieved a no-load temperature of 23.8 K with 330 W of electric input power at a rejection temperature of 279 K. When the input power increases to 400 W, it can achieve a cooling capacity of 4.7 W/40 K while rejecting heat at 279 K yielding an efficiency of 7.02% relative to Carnot. It achieves a cooling capacity of 5 W/40 K with an input power of 450 W. It takes 10 minutes for the SPTC to cool to its no-load temperature of 40 K from 295 K.

Flat and ultra-broadband two-pump fiber optical parametric amplifiers based on photonic crystal fibers

NASA Astrophysics Data System (ADS)

Cao, Nan; Zhu, Hongna; Li, Peipei; Taccheo, Stefano; Zhu, Yuanna; Gao, Xiaorong; Wang, Zeyong

2018-06-01

A two-pump fiber optical parametric amplifier (FOPA) based on the photonic crystal fiber (PCF) in the telecommunication region is investigated numerically. The fiber loss and pump depletion are considered. The influences of the fiber length, input signal power, input pump power, and the center pump wavelength on the gain bandwidth, flatness, and peak gain are discussed. The 6-wave model-based analysis of two-pump FOPA is also achieved and compared with that based on the 4-wave model; furthermore, the gain properties of the FOPA based on the 6-wave model are optimized and investigated. The comparison results show that the PCF-based two-pump FOPA achieves flatter and wider gain spectra with less fiber length and input pump power compared to the two-pump FOPA based on the normal highly nonlinear fiber, where the obtained results show the great potential of the FOPA for the optical communication system.

Flat and ultra-broadband two-pump fiber optical parametric amplifiers based on photonic crystal fibers

NASA Astrophysics Data System (ADS)

Cao, Nan; Zhu, Hongna; Li, Peipei; Taccheo, Stefano; Zhu, Yuanna; Gao, Xiaorong; Wang, Zeyong

2018-03-01

A two-pump fiber optical parametric amplifier (FOPA) based on the photonic crystal fiber (PCF) in the telecommunication region is investigated numerically. The fiber loss and pump depletion are considered. The influences of the fiber length, input signal power, input pump power, and the center pump wavelength on the gain bandwidth, flatness, and peak gain are discussed. The 6-wave model-based analysis of two-pump FOPA is also achieved and compared with that based on the 4-wave model; furthermore, the gain properties of the FOPA based on the 6-wave model are optimized and investigated. The comparison results show that the PCF-based two-pump FOPA achieves flatter and wider gain spectra with less fiber length and input pump power compared to the two-pump FOPA based on the normal highly nonlinear fiber, where the obtained results show the great potential of the FOPA for the optical communication system.

Road simulation for four-wheel vehicle whole input power spectral density

NASA Astrophysics Data System (ADS)

Wang, Jiangbo; Qiang, Baomin

2017-05-01

As the vibration of running vehicle mainly comes from road and influence vehicle ride performance. So the road roughness power spectral density simulation has great significance to analyze automobile suspension vibration system parameters and evaluate ride comfort. Firstly, this paper based on the mathematical model of road roughness power spectral density, established the integral white noise road random method. Then in the MATLAB/Simulink environment, according to the research method of automobile suspension frame from simple two degree of freedom single-wheel vehicle model to complex multiple degrees of freedom vehicle model, this paper built the simple single incentive input simulation model. Finally the spectrum matrix was used to build whole vehicle incentive input simulation model. This simulation method based on reliable and accurate mathematical theory and can be applied to the random road simulation of any specified spectral which provides pavement incentive model and foundation to vehicle ride performance research and vibration simulation.

NEXT Long-Duration Test After 11,570 h and 237 kg of Xenon Processed

NASA Technical Reports Server (NTRS)

Soulas, George C.; Patterson, Michael J.; Herman, Daniel A.

2009-01-01

The NASA s Evolutionary Xenon Thruster (NEXT) program is developing the next-generation ion propulsion system with significant enhancements beyond the state-of-the-art in ion propulsion to provide future NASA science missions with enhanced mission capabilities at a low total development cost. As part of a comprehensive thruster service life assessment utilizing both testing and analyses, a Long-Duration Test (LDT) was initiated to validate and qualify the NEXT propellant throughput capability to a qualification-level of 450 kg, 1.5 times the mission-derived throughput requirement of 300 kg. This wear test is being conducted with a modified, flight-representative NEXT engineering model ion thruster, designated EM3. As of September 1, 2007, the thruster has accumulated 11,570 h of operation primarily at the thruster full-input-power of 6.9 kW with 3.52 A beam current and 1800 V beam power supply voltage. The thruster has processed 237 kg of xenon surpassing the NSTAR propellant throughput demonstrated during the extended life testing of the Deep Space 1 (DS1) flight spare. The NEXT LDT has demonstrated a total impulse of 9.78 10(exp 6) N(dot)s; the highest total impulse ever demonstrated by an ion thruster. Thruster performance tests are conducted periodically over the entire NEXT throttle table with input power ranging 0.5 to 6.9 kW. Thruster performance parameters including thrust, input power, specific impulse, and thruster efficiency have been nominal with little variation to date. Lifetime-limiting component erosion rates have been consistent with the NEXT service life assessment, which predicts the earliest failure sometime after 750 kg of xenon propellant throughput; well beyond the mission-derived lifetime requirement. The NEXT wear test data confirm that the erosion of the discharge keeper orifice, enlarging of nominal-current-density accelerator grid aperture cusps at full-power, and the decrease in cold grid-gap observed during NSTAR wear testing have been mitigated in the NEXT design. NEXT grid-gap data indicate a hot grid-gap at full-power that is 60 percent of the nominal cold grid-gap. This paper presents the status of the NEXT LDT to date with emphasis on comparison to the NSTAR extended life test results.

NEXT Long-Duration Test Plume and Wear Characteristics after 16,550 h of Operation and 337 kg of Xenon Processed

NASA Technical Reports Server (NTRS)

Herman, Daniel A.; Soulas, George C.; Patterson, Michael J.

2009-01-01

The NASA s Evolutionary Xenon Thruster (NEXT) program is developing the next-generation ion propulsion system with significant enhancements beyond the state-of-the-art. The NEXT ion propulsion system provides improved mission capabilities for future NASA science missions to enhance and enable Discovery, New Frontiers, and Flagship-type NASA missions. As part of a comprehensive thruster service life assessment utilizing both testing and analyses, a Long-Duration Test (LDT) was initiated to validate and qualify the NEXT propellant throughput capability to a qualification-level of 450 kg, 1.5 times the mission-derived throughput requirement of 300 kg. This wear test is being conducted with a modified, flight-representative NEXT engineering model ion thruster, designated EM3. As of June 25, 2008, the thruster has accumulated 16,550 h of operation: the first 13,042 h at the thruster full-input-power of 6.9 kW with 3.52 A beam current and 1800 V beam power supply voltage. Operation since 13,042 h, i.e., the most recent 3,508 h, has been at an input power of 4.7 kW with 3.52 A beam current and 1180 V beam power supply voltage. The thruster has processed 337 kg of xenon (Xe) surpassing the NSTAR propellant throughput demonstrated during the extended life testing of the Deep Space 1 flight spare. The NEXT LDT has demonstrated a total impulse of 13.3 106 N s; the highest total impulse ever demonstrated by an ion thruster. Thruster plume diagnostics and erosion measurements are obtained periodically over the entire NEXT throttle table with input power ranging 0.5 to 6.9 kW. Observed thruster component erosion rates are consistent with predictions and the thruster service life assessment. There have not been any observed anomalous erosion and all erosion estimates indicate a thruster throughput capability that exceeds 750 kg of Xe, an equivalent of 36,500 h of continuous operation at the full-power operating condition. This paper presents the erosion measurements and plume diagnostic results for the NEXT LDT to date with emphasis on the change in thruster operating condition and resulting impact on wear characteristics. Ion optics grid-gap data, both cold and operating, are presented. Performance and wear predictions for the LDT throttle profile are presented.

On-chip remote charger model using plasmonic island circuit

NASA Astrophysics Data System (ADS)

Ali, J.; Youplao, P.; Pornsuwancharoen, N.; Aziz, M. S.; Chiangga, S.; Amiri, I. S.; Punthawanunt, S.; Singh, G.; Yupapin, P.

2018-06-01

We propose the remote charger model using the light fidelity (LiFi) transmission and integrate microring resonator circuit. It consists of the stacked layers of silicon-graphene-gold materials known as a plasmonic island placed at the center of the modified add-drop filter. The input light power from the remote LiFi can enter into the island via a silicon waveguide. The optimized input power is obtained by the coupled micro-lens on the silicon surface. The induced electron mobility generated in the gold layer by the interfacing layer between silicon-graphene. This is the reversed interaction of the whispering gallery mode light power of the microring system, in which the generated power is fed back into the microring circuit. The electron mobility is the required output and obtained at the device ports and characterized for the remote current source applications. The obtained calculation results have shown that the output current of ∼2.5 × 10-11 AW-1, with the gold height of 1.0 μm and the input power of 5.0 W is obtained at the output port, which is shown the potential application for a short range free pace remote charger.

Design of control system based on SCM music fountain

NASA Astrophysics Data System (ADS)

Li, Biqing; Li, Zhao; Jiang, Suping

2018-06-01

The design of the design of a microprocessor controlled by simple circuit, introduced this design applied to the components, and draw the main flow chart presentation. System is the use of an external music source, the intensity of the input audio signal lights will affect the light off, the fountain spray of water level will be based on changes in the lantern light off. This design uses a single-chip system is simple, powerful, good reliability and low cost.

The effect of variable S/N on the subjective evaluation of protection ratios for direct-TV satellite services

NASA Technical Reports Server (NTRS)

Groumpos, P. P.; Dimitriadis, B. D.; Whyte, W.

1984-01-01

Protection ratios, the ratio of wanted-to-unwanted signal power at the receiver input, for acceptable picture quality were experimentally evaluated for four different still pictures. The variation of carrier-to-interference, C/I, with picture impairment grade is investigated when different noise levels are present. Results are presented which show the relationship between the impairment grade and the C/I ratio for FM/TV co-channel systems under variable S/N conditions.

Probabilistic Analysis Techniques Applied to Complex Spacecraft Power System Modeling

NASA Technical Reports Server (NTRS)

Hojnicki, Jeffrey S.; Rusick, Jeffrey J.

2005-01-01

Electric power system performance predictions are critical to spacecraft, such as the International Space Station (ISS), to ensure that sufficient power is available to support all the spacecraft s power needs. In the case of the ISS power system, analyses to date have been deterministic, meaning that each analysis produces a single-valued result for power capability because of the complexity and large size of the model. As a result, the deterministic ISS analyses did not account for the sensitivity of the power capability to uncertainties in model input variables. Over the last 10 years, the NASA Glenn Research Center has developed advanced, computationally fast, probabilistic analysis techniques and successfully applied them to large (thousands of nodes) complex structural analysis models. These same techniques were recently applied to large, complex ISS power system models. This new application enables probabilistic power analyses that account for input uncertainties and produce results that include variations caused by these uncertainties. Specifically, N&R Engineering, under contract to NASA, integrated these advanced probabilistic techniques with Glenn s internationally recognized ISS power system model, System Power Analysis for Capability Evaluation (SPACE).

Increased Energy Delivery for Parallel Battery Packs with No Regulated Bus

NASA Astrophysics Data System (ADS)

Hsu, Chung-Ti

In this dissertation, a new approach to paralleling different battery types is presented. A method for controlling charging/discharging of different battery packs by using low-cost bi-directional switches instead of DC-DC converters is proposed. The proposed system architecture, algorithms, and control techniques allow batteries with different chemistry, voltage, and SOC to be properly charged and discharged in parallel without causing safety problems. The physical design and cost for the energy management system is substantially reduced. Additionally, specific types of failures in the maximum power point tracking (MPPT) in a photovoltaic (PV) system when tracking only the load current of a DC-DC converter are analyzed. The periodic nonlinear load current will lead MPPT realized by the conventional perturb and observe (P&O) algorithm to be problematic. A modified MPPT algorithm is proposed and it still only requires typically measured signals, yet is suitable for both linear and periodic nonlinear loads. Moreover, for a modular DC-DC converter using several converters in parallel, the input power from PV panels is processed and distributed at the module level. Methods for properly implementing distributed MPPT are studied. A new approach to efficient MPPT under partial shading conditions is presented. The power stage architecture achieves fast input current change rate by combining a current-adjustable converter with a few converters operating at a constant current.

Improved NASA-ANOPP Noise Prediction Computer Code for Advanced Subsonic Propulsion Systems. Volume 2; Fan Suppression Model Development

NASA Technical Reports Server (NTRS)

Kontos, Karen B.; Kraft, Robert E.; Gliebe, Philip R.

1996-01-01

The Aircraft Noise Predication Program (ANOPP) is an industry-wide tool used to predict turbofan engine flyover noise in system noise optimization studies. Its goal is to provide the best currently available methods for source noise prediction. As part of a program to improve the Heidmann fan noise model, models for fan inlet and fan exhaust noise suppression estimation that are based on simple engine and acoustic geometry inputs have been developed. The models can be used to predict sound power level suppression and sound pressure level suppression at a position specified relative to the engine inlet.

Payload accommodation and development planning tools - A Desktop Resource Leveling Model (DRLM)

NASA Technical Reports Server (NTRS)

Hilchey, John D.; Ledbetter, Bobby; Williams, Richard C.

1989-01-01

The Desktop Resource Leveling Model (DRLM) has been developed as a tool to rapidly structure and manipulate accommodation, schedule, and funding profiles for any kind of experiments, payloads, facilities, and flight systems or other project hardware. The model creates detailed databases describing 'end item' parameters, such as mass, volume, power requirements or costs and schedules for payload, subsystem, or flight system elements. It automatically spreads costs by calendar quarters and sums costs or accommodation parameters by total project, payload, facility, payload launch, or program phase. Final results can be saved or printed out, automatically documenting all assumptions, inputs, and defaults.

Sliding-mode control of single input multiple output DC-DC converter

NASA Astrophysics Data System (ADS)

Zhang, Libo; Sun, Yihan; Luo, Tiejian; Wan, Qiyang

2016-10-01

Various voltage levels are required in the vehicle mounted power system. A conventional solution is to utilize an independent multiple output DC-DC converter whose cost is high and control scheme is complicated. In this paper, we design a novel SIMO DC-DC converter with sliding mode controller. The proposed converter can boost the voltage of a low-voltage input power source to a controllable high-voltage DC bus and middle-voltage output terminals, which endow the converter with characteristics of simple structure, low cost, and convenient control. In addition, the sliding mode control (SMC) technique applied in our converter can enhance the performances of a certain SIMO DC-DC converter topology. The high-voltage DC bus can be regarded as the main power source to the high-voltage facility of the vehicle mounted power system, and the middle-voltage output terminals can supply power to the low-voltage equipment on an automobile. In the respect of control algorithm, it is the first time to propose the SMC-PID (Proportion Integration Differentiation) control algorithm, in which the SMC algorithm is utilized and the PID control is attended to the conventional SMC algorithm. The PID control increases the dynamic ability of the SMC algorithm by establishing the corresponding SMC surface and introducing the attached integral of voltage error, which endow the sliding-control system with excellent dynamic performance. At last, we established the MATLAB/SIMULINK simulation model, tested performance of the system, and built the hardware prototype based on Digital Signal Processor (DSP). Results show that the sliding mode control is able to track a required trajectory, which has robustness against the uncertainties and disturbances.

Sliding-mode control of single input multiple output DC-DC converter.

PubMed

Zhang, Libo; Sun, Yihan; Luo, Tiejian; Wan, Qiyang

2016-10-01

Various voltage levels are required in the vehicle mounted power system. A conventional solution is to utilize an independent multiple output DC-DC converter whose cost is high and control scheme is complicated. In this paper, we design a novel SIMO DC-DC converter with sliding mode controller. The proposed converter can boost the voltage of a low-voltage input power source to a controllable high-voltage DC bus and middle-voltage output terminals, which endow the converter with characteristics of simple structure, low cost, and convenient control. In addition, the sliding mode control (SMC) technique applied in our converter can enhance the performances of a certain SIMO DC-DC converter topology. The high-voltage DC bus can be regarded as the main power source to the high-voltage facility of the vehicle mounted power system, and the middle-voltage output terminals can supply power to the low-voltage equipment on an automobile. In the respect of control algorithm, it is the first time to propose the SMC-PID (Proportion Integration Differentiation) control algorithm, in which the SMC algorithm is utilized and the PID control is attended to the conventional SMC algorithm. The PID control increases the dynamic ability of the SMC algorithm by establishing the corresponding SMC surface and introducing the attached integral of voltage error, which endow the sliding-control system with excellent dynamic performance. At last, we established the MATLAB/SIMULINK simulation model, tested performance of the system, and built the hardware prototype based on Digital Signal Processor (DSP). Results show that the sliding mode control is able to track a required trajectory, which has robustness against the uncertainties and disturbances.

Ferroelectric Based High Power Components for L-Band Accelerator Applications

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

Kanareykin, Alex; Jing, Chunguang; Kostin, Roman

2018-01-16

We are developing a new electronic device to control the power in particle accelerators. The key technology is a new nanostructured material developed by Euclid that changes its properties with an applied electric field. Both superconducting and conventional accelerating structures require fast electronic control of the input rf power. A fast controllable phase shifter would allow for example the control of the rf power delivered to multiple accelerating cavities from a single power amplifier. Nonlinear ferroelectric microwave components can control the tuning or the input power coupling for rf cavities. Applying a bias voltage across a nonlinear ferroelectric changes itsmore » permittivity. This effect can be used to cause a phase change of a propagating rf signal or change the resonant frequency of a cavity. The key is the development of a low loss highly tunable ferroelectric material.« less

A multi-channel isolated power supply in non-equipotential circuit

NASA Astrophysics Data System (ADS)

Li, Xiang; Zhao, Bo-Wen; Zhang, Yan-Chi; Xie, Da

2018-04-01

A multi-channel isolation power supply is designed for the problems of different MOSFET or IGBT in the non-equipotential circuit in this paper. It mainly includes the square wave generation circuit, the high-frequency transformer and the three-terminal stabilized circuit. The first part is used to generate the 24V square wave, and as the input of the magnetic ring transformer. In the second part, the magnetic ring transformer consists of one input and three outputs to realize multi-channel isolation output. The third part can output different potential and realize non-equal potential function through the three-terminal stabilized chip. In addition, the multi-channel isolation power source proposed in this paper is Small size, high reliability and low price, and it is convenient for power electronic switches that operate on multiple different potentials. Therefore, the research on power supply of power electronic circuit has practical significance.

The Impacts of Heating Strategy on Soil Moisture Estimation Using Actively Heated Fiber Optics.

PubMed

Dong, Jianzhi; Agliata, Rosa; Steele-Dunne, Susan; Hoes, Olivier; Bogaard, Thom; Greco, Roberto; van de Giesen, Nick

2017-09-13

Several recent studies have highlighted the potential of Actively Heated Fiber Optics (AHFO) for high resolution soil moisture mapping. In AHFO, the soil moisture can be calculated from the cumulative temperature ( T cum ), the maximum temperature ( T max ), or the soil thermal conductivity determined from the cooling phase after heating ( λ ). This study investigates the performance of the T cum , T max and λ methods for different heating strategies, i.e., differences in the duration and input power of the applied heat pulse. The aim is to compare the three approaches and to determine which is best suited to field applications where the power supply is limited. Results show that increasing the input power of the heat pulses makes it easier to differentiate between dry and wet soil conditions, which leads to an improved accuracy. Results suggest that if the power supply is limited, the heating strength is insufficient for the λ method to yield accurate estimates. Generally, the T cum and T max methods have similar accuracy. If the input power is limited, increasing the heat pulse duration can improve the accuracy of the AHFO method for both of these techniques. In particular, extending the heating duration can significantly increase the sensitivity of T cum to soil moisture. Hence, the T cum method is recommended when the input power is limited. Finally, results also show that up to 50% of the cable temperature change during the heat pulse can be attributed to soil background temperature, i.e., soil temperature changed by the net solar radiation. A method is proposed to correct this background temperature change. Without correction, soil moisture information can be completely masked by the background temperature error.

The Impacts of Heating Strategy on Soil Moisture Estimation Using Actively Heated Fiber Optics

PubMed Central

Dong, Jianzhi; Agliata, Rosa; Steele-Dunne, Susan; Hoes, Olivier; Bogaard, Thom; Greco, Roberto; van de Giesen, Nick

2017-01-01

Several recent studies have highlighted the potential of Actively Heated Fiber Optics (AHFO) for high resolution soil moisture mapping. In AHFO, the soil moisture can be calculated from the cumulative temperature (Tcum), the maximum temperature (Tmax), or the soil thermal conductivity determined from the cooling phase after heating (λ). This study investigates the performance of the Tcum, Tmax and λ methods for different heating strategies, i.e., differences in the duration and input power of the applied heat pulse. The aim is to compare the three approaches and to determine which is best suited to field applications where the power supply is limited. Results show that increasing the input power of the heat pulses makes it easier to differentiate between dry and wet soil conditions, which leads to an improved accuracy. Results suggest that if the power supply is limited, the heating strength is insufficient for the λ method to yield accurate estimates. Generally, the Tcum and Tmax methods have similar accuracy. If the input power is limited, increasing the heat pulse duration can improve the accuracy of the AHFO method for both of these techniques. In particular, extending the heating duration can significantly increase the sensitivity of Tcum to soil moisture. Hence, the Tcum method is recommended when the input power is limited. Finally, results also show that up to 50% of the cable temperature change during the heat pulse can be attributed to soil background temperature, i.e., soil temperature changed by the net solar radiation. A method is proposed to correct this background temperature change. Without correction, soil moisture information can be completely masked by the background temperature error. PMID:28902141

Control and optimization system

DOEpatents

Xinsheng, Lou

2013-02-12

A system for optimizing a power plant includes a chemical loop having an input for receiving an input parameter (270) and an output for outputting an output parameter (280), a control system operably connected to the chemical loop and having a multiple controller part (230) comprising a model-free controller. The control system receives the output parameter (280), optimizes the input parameter (270) based on the received output parameter (280), and outputs an optimized input parameter (270) to the input of the chemical loop to control a process of the chemical loop in an optimized manner.

Generation of electrical power

DOEpatents

Hursen, Thomas F.; Kolenik, Steven A.; Purdy, David L.

1976-01-01

A heat-to-electricity converter is disclosed which includes a radioactive heat source and a thermoelectric element of relatively short overall length capable of delivering a low voltage of the order of a few tenths of a volt. Such a thermoelectric element operates at a higher efficiency than longer higher-voltage elements; for example, elements producing 6 volts. In the generation of required power, thermoelectric element drives a solid-state converter which is controlled by input current rather than input voltage and operates efficiently for a high signal-plus-noise to signal ratio of current. The solid-state converter has the voltage gain necessary to deliver the required voltage at the low input of the thermoelectric element.

TRIAC/SCR proportional control circuit

DOEpatents

Hughes, Wallace J.

1999-01-01

A power controller device which uses a voltage-to-frequency converter in conjunction with a zero crossing detector to linearly and proportionally control AC power being supplied to a load. The output of the voltage-to frequency converter controls the "reset" input of a R-S flip flop, while an "0" crossing detector controls the "set" input. The output of the flip flop triggers a monostable multivibrator controlling the SCR or TRIAC firing circuit connected to the load. Logic gates prevent the direct triggering of the multivibrator in the rare instance where the "reset" and "set" inputs of the flip flop are in coincidence. The control circuit can be supplemented with a control loop, providing compensation for line voltage variations.

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

Chinthavali, Madhu Sudhan; Campbell, Steven L

This paper presents an analytical model for wireless power transfer system used in electric vehicle application. The equivalent circuit model for each major component of the system is described, including the input voltage source, resonant network, transformer, nonlinear diode rectifier load, etc. Based on the circuit model, the primary side compensation capacitance, equivalent input impedance, active / reactive power are calculated, which provides a guideline for parameter selection. Moreover, the voltage gain curve from dc output to dc input is derived as well. A hardware prototype with series-parallel resonant stage is built to verify the developed model. The experimental resultsmore » from the hardware are compared with the model predicted results to show the validity of the model.« less

Signal bi-amplification in networks of unidirectionally coupled MEMS

NASA Astrophysics Data System (ADS)

Tchakui, Murielle Vanessa; Woafo, Paul; Colet, Pere

2016-01-01

The purpose of this paper is to analyze the propagation and the amplification of an input signal in networks of unidirectionally coupled micro-electro-mechanical systems (MEMS). Two types of external excitations are considered: sinusoidal and stochastic signals. We show that sinusoidal signals are amplified up to a saturation level which depends on the transmission rate and despite MEMS being nonlinear the sinusoidal shape is well preserved if the number of MEMS is not too large. However, increasing the number of MEMS, there is an instability that leads to chaotic behavior and which is triggered by the amplification of the harmonics generated by the nonlinearities. We also show that for stochastic input signals, the MEMS array acts as a band-pass filter and after just a few elements the signal has a narrow power spectra.

solar thermal power systems advanced solar thermal technology project, advanced subsystems development

NASA Technical Reports Server (NTRS)

1979-01-01

The preliminary design for a prototype small (20 kWe) solar thermal electric generating unit was completed, consisting of several subsystems. The concentrator and the receiver collect solar energy and a thermal buffer storage with a transport system is used to provide a partially smoothed heat input to the Stirling engine. A fossil-fuel combustor is included in the receiver designs to permit operation with partial or no solar insolation (hybrid). The engine converts the heat input into mechanical action that powers a generator. To obtain electric power on a large scale, multiple solar modules will be required to operate in parallel. The small solar electric power plant used as a baseline design will provide electricity at remote sites and small communities.

Three phase power factor controller

NASA Technical Reports Server (NTRS)

Nola, F. J. (Inventor)

1984-01-01

A power control circuit for a three phase induction motor is described. Power factors for the three phases are summed to provide a control signal, and this control signal is particularly filtered and then employed to control the duty cycle of each phase of input power to the motor.

Design of a 0.13 µm SiGe Limiting Amplifier with 14.6 THz Gain-Bandwidth-Product

NASA Astrophysics Data System (ADS)

Park, Sehoon; Du, Xuan-Quang; Grözing, Markus; Berroth, Manfred

2017-09-01

This paper presents the design of a limiting amplifier with 1-to-3 fan-out implementation in a 0.13 µm SiGe BiCMOS technology and gives a detailed guideline to determine the circuit parameters of the amplifier for optimum high-frequency performance based on simplified gain estimations. The proposed design uses a Cherry-Hooper topology for bandwidth enhancement and is optimized for maximum group delay flatness to minimize phase distortion of the input signal. With regard to a high integration density and a small chip area, the design employs no passive inductors which might be used to boost the circuit bandwidth with inductive peaking. On a RLC-extracted post-layout simulation level, the limiting amplifier exhibits a gain-bandwidth-product of 14.6 THz with 56.6 dB voltage gain and 21.5 GHz 3 dB bandwidth at a peak-to-peak input voltage of 1.5 mV. The group delay variation within the 3 dB bandwidth is less than 0.5 ps and the power dissipation at a power supply voltage of 3 V including output drivers is 837 mW.

A Reactor Development Scenario for the FUZE Shear-flow Stabilized Z-pinch

NASA Astrophysics Data System (ADS)

McLean, H. S.; Higginson, D. P.; Schmidt, A.; Tummel, K. K.; Shumlak, U.; Nelson, B. A.; Claveau, E. L.; Golingo, R. P.; Weber, T. R.

2016-10-01

We present a conceptual design, scaling calculations, and a development path for a pulsed fusion reactor based on the shear-flow-stabilized Z-pinch device. Experiments performed on the ZaP device have demonstrated stable operation for 40 us at 150 kA total discharge current (with 100 kA in the pinch) for pinches that are 1cm in diameter and 100 cm long. Scaling calculations show that achieving stabilization for a pulse of 100 usec, for discharge current 1.5 MA, in a shortened pinch 50 cm, results in a pinch diameter of 200 um and a reactor plant Q 5 for reasonable assumptions of the various system efficiencies. We propose several key intermediate performance levels in order to justify further development. These include achieving operation at pinch currents of 300 kA, where Te and Ti are calculated to exceed 1 keV, 700 kA where fusion power exceeds pinch input power, and 1 MA where fusion energy per pulse exceeds input energy per pulse. This work funded by USDOE ARPAe ALPHA Program and performed under the auspices of Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-697801.

Helicon double layer thruster operation in a low magnetic field mode

NASA Astrophysics Data System (ADS)

Harle, T.; Pottinger, S. J.; Lappas, V. J.

2013-02-01

Direct thrust measurements are made of a helicon double layer thruster operating in a low magnetic field mode. The relationship between the imposed axial magnetic field and generated thrust is investigated for a radio frequency input power range 200-500 W for propellant flow rates of 16.5 and 20 sccm (0.46 and 0.55 mg s-1) of argon. The measured thrust shows a strong dependence on the magnetic field strength, increasing by up to a factor of 5 compared with the minimum thrust level recorded. A peak thrust of 0.4-1.1 mN depending on thruster operating conditions is obtained. This increase is observed to take place over a small range of peak magnetic field strengths in the region of 70-110 G. The magnitude of the thrust and the corresponding magnitude of the magnetic field at which the peak thrust occurs is shown to increase with increasing input power for a given propellant flow rate. The ion current determined using a retarding field energy analyser and the electron number density found using a microwave resonator probe both correlate with the observed trend in thrust as a function of applied magnetic field.

The impact of visual gaze direction on auditory object tracking.

PubMed

Pomper, Ulrich; Chait, Maria

2017-07-05

Subjective experience suggests that we are able to direct our auditory attention independent of our visual gaze, e.g when shadowing a nearby conversation at a cocktail party. But what are the consequences at the behavioural and neural level? While numerous studies have investigated both auditory attention and visual gaze independently, little is known about their interaction during selective listening. In the present EEG study, we manipulated visual gaze independently of auditory attention while participants detected targets presented from one of three loudspeakers. We observed increased response times when gaze was directed away from the locus of auditory attention. Further, we found an increase in occipital alpha-band power contralateral to the direction of gaze, indicative of a suppression of distracting input. Finally, this condition also led to stronger central theta-band power, which correlated with the observed effect in response times, indicative of differences in top-down processing. Our data suggest that a misalignment between gaze and auditory attention both reduce behavioural performance and modulate underlying neural processes. The involvement of central theta-band and occipital alpha-band effects are in line with compensatory neural mechanisms such as increased cognitive control and the suppression of task irrelevant inputs.

225-255-GHz InP DHBT Frequency Tripler MMIC Using Complementary Split-Ring Resonator

NASA Astrophysics Data System (ADS)

Li, Xiao; Zhang, Yong; Li, Oupeng; Sun, Yan; Lu, Haiyan; Cheng, Wei; Xu, Ruimin

2017-02-01

In this paper, a novel design of frequency tripler monolithic microwave integrated circuit (MMIC) using complementary split-ring resonator (CSRR) is proposed based on 0.5-μm InP DHBT process. The CSRR-loaded microstrip structure is integrated in the tripler as a part of impedance matching network to suppress the fundamental harmonic, and another frequency tripler based on conventional band-pass filter is presented for comparison. The frequency tripler based on CSRR-loaded microstrip generates an output power between -8 and -4 dBm from 228 to 255 GHz when the input power is 6 dBm. The suppression of fundamental harmonic is better than 20 dBc at 77-82 GHz input frequency within only 0.15 × 0.15 mm2 chip area of the CSRR structure on the ground layer. Compared with the frequency tripler based on band-pass filter, the tripler using CSRR-loaded microstrip obtains a similar suppression level of unwanted harmonics and higher conversion gain within a much smaller chip area. To our best knowledge, it is the first time that CSRR is used for harmonic suppression of frequency multiplier at such high frequency band.

High Frequency Single-Stage Multi-Bypass Pulse Tube Cryocooler for 23.8K

NASA Astrophysics Data System (ADS)

Yang, Junling; Hou, Xiaofeng; Yang, Luwei; Zhou, Yuan; Zhang, Liang

2008-03-01

A below 30K single-stage high-frequency multi-bypass pulse tube cryocooler(PTC) is introduced in this paper. At present, the lowest temperature of 27.46K has been achieved with input power of 100W and 23.8K with input power of 200W. Experiments show that if the area of multi-bypass and the length of inertance tube matching well, a better performance of PTC will be obtained.

PLEXOS Input Data Generator

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

The PLEXOS Input Data Generator (PIDG) is a tool that enables PLEXOS users to better version their data, automate data processing, collaborate in developing inputs, and transfer data between different production cost modeling and other power systems analysis software. PIDG can process data that is in a generalized format from multiple input sources, including CSV files, PostgreSQL databases, and PSS/E .raw files and write it to an Excel file that can be imported into PLEXOS with only limited manual intervention.

Analog phase lock between two lasers at LISA power levels

NASA Astrophysics Data System (ADS)

Diekmann, Christian; Steier, Frank; Sheard, Benjamin; Heinzel, Gerhard; Danzmann, Karsten

2009-03-01

This paper presents the implementation of an analog optical phase-locked-loop with an offset frequency of about 20MHz between two lasers, where the detected light powers were of the order of 31 pW and 200 μW. The goal of this setup was the design and characterization of a photodiode transimpedance amplifier for application in LISA. By application of a transimpedance amplifier designed to have low noise and low power consumption, the phase noise between the two lasers was a factor of two above the shot noise limit down to 60mHz. The achievable phase sensitivity depends ultimately on the available power of the highly attenuated master laser and on the input current noise of the transimpedance amplifier of the photodetector. The limiting noise source below 60mHz was the analog phase measurement system that was used in this experiment. A digital phase measurement system that is currently under development at the AEI will be used in the near future. Its application should improve the sensitivity.

An All-Digital Fast Tracking Switching Converter with a Programmable Order Loop Controller for Envelope Tracking RF Power Amplifiers

PubMed Central

Anabtawi, Nijad; Ferzli, Rony; Harmanani, Haidar M.

2017-01-01

This paper presents a step down, switched mode power converter for use in multi-standard envelope tracking radio frequency power amplifiers (RFPA). The converter is based on a programmable order sigma delta modulator that can be configured to operate with either 1st, 2nd, 3rd or 4th order loop filters, eliminating the need for a bulky passive output filter. Output ripple, sideband noise and spectral emission requirements of different wireless standards can be met by configuring the modulator’s filter order and converter’s sampling frequency. The proposed converter is entirely digital and is implemented in 14nm bulk CMOS process for post layout verification. For an input voltage of 3.3V, the converter’s output can be regulated to any voltage level from 0.5V to 2.5V, at a nominal switching frequency of 150MHz. It achieves a maximum efficiency of 94% at 1.5 W output power. PMID:28919657

Brayton Power Conversion System Parametric Design Modelling for Nuclear Electric Propulsion

NASA Technical Reports Server (NTRS)

Ashe, Thomas L.; Otting, William D.

1993-01-01

The parametrically based closed Brayton cycle (CBC) computer design model was developed for inclusion into the NASA LeRC overall Nuclear Electric Propulsion (NEP) end-to-end systems model. The code is intended to provide greater depth to the NEP system modeling which is required to more accurately predict the impact of specific technology on system performance. The CBC model is parametrically based to allow for conducting detailed optimization studies and to provide for easy integration into an overall optimizer driver routine. The power conversion model includes the modeling of the turbines, alternators, compressors, ducting, and heat exchangers (hot-side heat exchanger and recuperator). The code predicts performance to significant detail. The system characteristics determined include estimates of mass, efficiency, and the characteristic dimensions of the major power conversion system components. These characteristics are parametrically modeled as a function of input parameters such as the aerodynamic configuration (axial or radial), turbine inlet temperature, cycle temperature ratio, power level, lifetime, materials, and redundancy.

Experiments and analysis of a compact electrothermal thruster

NASA Technical Reports Server (NTRS)

Asmussen, Jes; Whitehair, Stan

1988-01-01

The description and experimental performance of a compact microwave electrothermal thruster (MET) are presented. This thruster uses a coaxial applicator to couple microwave power into a high pressure discharge. Unlike earlier experiments, it uses no fused quartz in the discharge chamber or the nozzle. This allows high temperatures in the discharge chamber without quartz erosion and melting, thereby improving thruster performance and lifetime. The thruster design is compact, enhancing its potential as a space engine. Experimental tests using nitrogen and helium propellants with input powers levels of 200 W to 1.5 kW are presented. Experimental results, which produce energy efficiencies of 20 to 60 percent and specific impulse of 250 to 450 sec, compare favorably to previous experimental MET performance.

Multistaged stokes injected Raman capillary waveguide amplifier

DOEpatents

Kurnit, Norman A.

1980-01-01

A multistaged Stokes injected Raman capillary waveguide amplifier for providing a high gain Stokes output signal. The amplifier uses a plurality of optically coupled capillary waveguide amplifiers and one or more regenerative amplifiers to increase Stokes gain to a level sufficient for power amplification. Power amplification is provided by a multifocused Raman gain cell or a large diameter capillary waveguide. An external source of CO.sub.2 laser radiation can be injected into each of the capillary waveguide amplifier stages to increase Raman gain. Devices for injecting external sources of CO.sub.2 radiation include: dichroic mirrors, prisms, gratings and Ge Brewster plates. Alternatively, the CO.sub.2 input radiation to the first stage can be coupled and amplified between successive stages.

Transient Stability Assessment of Power Systems With Uncertain Renewable Generation: Preprint

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

Villegas Pico, Hugo Nestor; Aliprantis, Dionysios C.; Lin, Xiaojun

2017-08-09

The transient stability of a power system depends heavily on its operational state at the moment of a fault. In systems where the penetration of renewable generation is significant, the dispatch of the conventional fleet of synchronous generators is uncertain at the time of dynamic security analysis. Hence, the assessment of transient stability requires the solution of a system of nonlinear ordinary differential equations with unknown initial conditions and inputs. To this end, we set forth a computational framework that relies on Taylor polynomials, where variables are associated with the level of renewable generation. This paper describes the details ofmore » the method and illustrates its application on a nine-bus test system.« less

Cryogenic Evaluation of an Advanced DC/DC Converter Module for Deep Space Applications

NASA Technical Reports Server (NTRS)

Elbuluk, Malik E.; Hammoud, Ahmad; Gerber, Scott S.; Patterson, Richard

2003-01-01

DC/DC converters are widely used in power management, conditioning, and control of space power systems. Deep space applications require electronics that withstand cryogenic temperature and meet a stringent radiation tolerance. In this work, the performance of an advanced, radiation-hardened (rad-hard) commercial DC/DC converter module was investigated at cryogenic temperatures. The converter was investigated in terms of its steady state and dynamic operations. The output voltage regulation, efficiency, terminal current ripple characteristics, and output voltage response to load changes were determined in the temperature range of 20 to -140 C. These parameters were obtained at various load levels and at different input voltages. The experimental procedures along with the results obtained on the investigated converter are presented and discussed.

High performance ripple feedback for the buck unity-power-factor rectifier

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

Lo, Y.W.; King, R.J.

1995-03-01

The buck unity-power-factor rectifier has harmonic-free input current with complete load regulation down to zero output voltage. A new ``nonlinear ripple feedback`` is proposed which exactly cancels the spoiling effect of dc-side current ripple on the low-distortion ac line current waveforms, even for large amounts of ripple. This cancellation is independent of operating point and readily implemented with analog hardware, thereby permitting economies in the design of the dc filter while maintaining harmonic-free operation. Both large-signal and incremental analyses of the rectifier are given. Confirming experimental results from a 1-kW 48-V isolated battery charger operating with current-ripple levels ranging frommore » 50% to discontinuous-conduction-mode operation are given.« less

The Increase of Power Efficiency of Underground Coal Mining by the Forecasting of Electric Power Consumption

NASA Astrophysics Data System (ADS)

Efremenko, Vladimir; Belyaevsky, Roman; Skrebneva, Evgeniya

2017-11-01

In article the analysis of electric power consumption and problems of power saving on coal mines are considered. Nowadays the share of conditionally constant costs of electric power for providing safe working conditions underground on coal mines is big. Therefore, the power efficiency of underground coal mining depends on electric power expense of the main technological processes and size of conditionally constant costs. The important direction of increase of power efficiency of coal mining is forecasting of a power consumption and monitoring of electric power expense. One of the main approaches to reducing of electric power costs is increase in accuracy of the enterprise demand in the wholesale electric power market. It is offered to use artificial neural networks to forecasting of day-ahead power consumption with hourly breakdown. At the same time use of neural and indistinct (hybrid) systems on the principles of fuzzy logic, neural networks and genetic algorithms is more preferable. This model allows to do exact short-term forecasts at a small array of input data. A set of the input parameters characterizing mining-and-geological and technological features of the enterprise is offered.

A study on macroeconomic cost of CCS in Korea

NASA Astrophysics Data System (ADS)

Kim, Ji-Whan; Kim, Yoon Kyung

2015-04-01

CCS is an important measure for mitigating the problem of World Climate Change and already several projects are entered the step of commercialization. The benefits of CCS implementation ultimately depends on the alleviation level of CO2 on earth because it is caused by the mitigation of the World Climate Change problem. Thus it is possible not to coincide at same time between starting the CCS and getting the benefits. Considering the high costs of CCS, the time mismatch between imposing the costs and getting the benefits is apt to impose some heavy burden on the individual national economy. For this reason, at the political decision-making, the policy makers should consider the macroeconomic effects. Meanwhile, Korean electricity market's supply side is comprised of competitive production and a sole distributor(public enterprise) and then electricity is supplied by a single price structure(administered pricing). Under this condition, if CCS is introduced to power setor, electric charges must be increased and production costs will go high. High production costs will have unfavourable effects on disposable income, price level, purchasing power and so on. In order to minimize these effects, policy makers have to consider the economic effects of introducing CCS. This study estimates the microscopic cost of CCS using ICCSEM 2.0 methodology made by CO2CRC and after that, the macroeconomic effects of introducing CCS is estimated on the basis of microscopic cost estimating results. The macroeconomic effects of CCS applied to Power Generation sector are estimated using macroeconometrics model and Input-Output analysis. A macroeconometrics model is an analytical tool designed to describe the operation of the national economy. This model is usually applied to examine the dynamics of aggregate quantities such as the total amount of goods and services produced, total income earned, the level of employment of productive resources, the level of prices and so forth. Introducing the input-output relationship of Korean industries, the macroeconometrics model can show what response is caused by the CCS cost as supply and demand shock. This study is intended to provide a basic information for making reasonable policies which is to minimize the economic costs of introducing CCS.

Antitheft container for instruments

NASA Technical Reports Server (NTRS)

Kerley, J. J., Jr.

1979-01-01

Antitheft container is used to prevent theft of calculators, portable computers, and other small instruments. Container design is simple and flexible enough to allow easy access to display or input systems of instruments, while not interfering with power input to device.

High power ferrite microwave switch

NASA Technical Reports Server (NTRS)

Bardash, I.; Roschak, N. K.

1975-01-01

A high power ferrite microwave switch was developed along with associated electronic driver circuits for operation in a spaceborne high power microwave transmitter in geostationary orbit. Three units were built and tested in a space environment to demonstrate conformance to the required performance characteristics. Each unit consisted of an input magic-tee hybrid, two non-reciprocal latching ferrite phase shifters, an out short-slot 3 db quadrature coupler, a dual driver electronic circuit, and input logic interface circuitry. The basic mode of operation of the high power ferrite microwave switch is identical to that of a four-port, differential phase shift, switchable circulator. By appropriately designing the phase shifters and electronic driver circuits to operate in the flux-transfer magnetization mode, power and temperature insensitive operation was achieved. A list of the realized characteristics of the developed units is given.

Direct current ballast circuit for metal halide lamp

NASA Technical Reports Server (NTRS)

Lutus, P. (Inventor)

1981-01-01

A direct current ballast circuit for a two electrode metal halide lamp is described. Said direct current ballast circuit includes a low voltage DC input and a high frequency power amplifier and power transformer for developing a high voltage output. The output voltage is rectified by diodes and filtered by inductor and capacitor to provide a regulated DC output through commutating diodes to one terminal of the lamp at the output terminal. A feedback path from the output of the filter capacitor through the bias resistor to power the high frequency circuit which includes the power amplifier and the power transformer for sustaining circuit operations during low voltage transients on the input DC supply is described. A current sensor connected to the output of the lamp through terminal for stabilizing lamp current following breakdown of the lamp is described.

Push-pull switching power amplifier

NASA Technical Reports Server (NTRS)

Cuk, Slobodan M. (Inventor)

1980-01-01

A true push-pull switching power amplifier is disclosed utilizing two dc-to-dc converters. Each converter is comprised of two inductances, one inductance in series with a DC source and the other inductor in series with the output load, and an electrical energy transferring device with storage capability, namely storage capacitance, with suitable switching means between the inductances to obtain DC level conversion, where the switching means allows bidirectional current (and power) flow, and the switching means of one dc-to-dc converter is driven by the complement of a square-wave switching signal for the other dc-to-dc converter for true push-pull operation. For reduction of current ripple, the inductances in each of the two converters may be coupled, and with proper design of the coupling, the ripple can be reduced to zero at either the input or the output, but preferably the output.

Investigation of Saturation Effects in Ceramic Phosphors for Laser Lighting

PubMed Central

Krasnoshchoka, Anastasiia; Dam-Hansen, Carsten; Corell, Dennis Dan; Petersen, Paul Michael

2017-01-01

We report observations of saturation effects in a Ce:LuAG and Eu-doped nitride ceramic phosphor for conversion of blue laser light for white light generation. The luminous flux from the phosphors material increases linearly with the input power until saturation effects limit the conversion. It is shown that the temperature of the phosphor layer influences the saturation power level and the conversion efficiency. It is also shown that the correlated color temperature (CCT), phosphor conversion efficiency and color rendering index (CRI) are dependent both on the incident power and spot size diameter of the illumination. A phosphor conversion efficiency up to 140.8 lm/W with CRI of 89.4 was achieved. The saturation in a ceramic phosphor, when illuminated by high intensity laser diodes, is estimated to play the main role in limiting the available luminance from laser-based lighting systems. PMID:29292770

Dual regression physiological modeling of resting-state EPI power spectra: Effects of healthy aging.

PubMed

Viessmann, Olivia; Möller, Harald E; Jezzard, Peter

2018-02-02

Aging and disease-related changes in the arteriovasculature have been linked to elevated levels of cardiac cycle-induced pulsatility in the cerebral microcirculation. Functional magnetic resonance imaging (fMRI), acquired fast enough to unalias the cardiac frequency contributions, can be used to study these physiological signals in the brain. Here, we propose an iterative dual regression analysis in the frequency domain to model single voxel power spectra of echo planar imaging (EPI) data using external recordings of the cardiac and respiratory cycles as input. We further show that a data-driven variant, without external physiological traces, produces comparable results. We use this framework to map and quantify cardiac and respiratory contributions in healthy aging. We found a significant increase in the spatial extent of cardiac modulated white matter voxels with age, whereas the overall strength of cardiac-related EPI power did not show an age effect. Copyright © 2018. Published by Elsevier Inc.

A 4H Silicon Carbide Gate Buffer for Integrated Power Systems

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

Ericson, N; Frank, S; Britton, C

2014-02-01

A gate buffer fabricated in a 2-mu m 4H silicon carbide (SiC) process is presented. The circuit is composed of an input buffer stage with a push-pull output stage, and is fabricated using enhancement mode N-channel FETs in a process optimized for SiC power switching devices. Simulation and measurement results of the fabricated gate buffer are presented and compared for operation at various voltage supply levels, with a capacitive load of 2 nF. Details of the design including layout specifics, simulation results, and directions for future improvement of this buffer are presented. In addition, plans for its incorporation into anmore » isolated high-side/low-side gate-driver architecture, fully integrated with power switching devices in a SiC process, are briefly discussed. This letter represents the first reported MOSFET-based gate buffer fabricated in 4H SiC.« less

Heating performances of a IC in-blanket ring array

NASA Astrophysics Data System (ADS)

Bosia, G.; Ragona, R.

2015-12-01

An important limiting factor to the use of ICRF as candidate heating method in a commercial reactor is due to the evanescence of the fast wave in vacuum and in most of the SOL layer, imposing proximity of the launching structure to the plasma boundary and causing, at the highest power level, high RF standing and DC rectified voltages at the plasma periphery, with frequent voltage breakdowns and enhanced local wall loading. In a previous work [1] the concept for an Ion Cyclotron Heating & Current Drive array (and using a different wave guide technology, a Lower Hybrid array) based on the use of periodic ring structure, integrated in the reactor blanket first wall and operating at high input power and low power density, was introduced. Based on the above concept, the heating performance of such array operating on a commercial fusion reactor is estimated.

Heating performances of a IC in-blanket ring array

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

Bosia, G., E-mail: gbosia@to.infn.it; Ragona, R.

2015-12-10

An important limiting factor to the use of ICRF as candidate heating method in a commercial reactor is due to the evanescence of the fast wave in vacuum and in most of the SOL layer, imposing proximity of the launching structure to the plasma boundary and causing, at the highest power level, high RF standing and DC rectified voltages at the plasma periphery, with frequent voltage breakdowns and enhanced local wall loading. In a previous work [1] the concept for an Ion Cyclotron Heating & Current Drive array (and using a different wave guide technology, a Lower Hybrid array) basedmore » on the use of periodic ring structure, integrated in the reactor blanket first wall and operating at high input power and low power density, was introduced. Based on the above concept, the heating performance of such array operating on a commercial fusion reactor is estimated.« less

MHD retrofit of steam power plants. Feasibility study. Summary and conclusions, Part I

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

Not Available

1979-07-01

The US Department of Energy Division of Magnetohydrodynamics (DOE/MHD) initiated this study to evaluate the feasibility of a retrofit option to reduce the time and cost of commercializing MHD. The MHD retrofit option will integrate a nominal 260 megawatt thermal (MWt) MHD topping cycle into an existing or scheduled private utility steam plant; this facility will test both the MHD system and the combined operation of the MHD/steam plant. The 260 MWt input level was determined to be the size which could most effectively demonstrate and verify the engineering design and operational characteristics of a coal-fired, open-cycle, MHD power plant.more » Details are presented. A goal of the MHD program is to have operational by the year 2003 a commercial size, fully integrated MHD plant. This would be accomplished by demonstrating commercial scale, baseload performance of a fully integrated, MHD/steam power plant. (WHK)« less

Design of an ultra low power third order continuous time current mode ΣΔ modulator for WLAN applications.

PubMed

Behzadi, Kobra; Baghelani, Masoud

2014-05-01

This paper presents a third order continuous time current mode ΣΔ modulator for WLAN 802.11b standard applications. The proposed circuit utilized feedback architecture with scaled and optimized DAC coefficients. At circuit level, we propose a modified cascade current mirror integrator with reduced input impedance which results in more bandwidth and linearity and hence improves the dynamic range. Also, a very fast and precise novel dynamic latch based current comparator is introduced with low power consumption. This ultra fast comparator facilitates increasing the sampling rate toward GHz frequencies. The modulator exhibits dynamic range of more than 60 dB for 20 MHz signal bandwidth and OSR of 10 while consuming only 914 μW from 1.8 V power supply. The FoM of the modulator is calculated from two different methods, and excellent performance is achieved for proposed modulator.

Design of an ultra low power third order continuous time current mode ΣΔ modulator for WLAN applications

PubMed Central

Behzadi, Kobra; Baghelani, Masoud

2013-01-01

This paper presents a third order continuous time current mode ΣΔ modulator for WLAN 802.11b standard applications. The proposed circuit utilized feedback architecture with scaled and optimized DAC coefficients. At circuit level, we propose a modified cascade current mirror integrator with reduced input impedance which results in more bandwidth and linearity and hence improves the dynamic range. Also, a very fast and precise novel dynamic latch based current comparator is introduced with low power consumption. This ultra fast comparator facilitates increasing the sampling rate toward GHz frequencies. The modulator exhibits dynamic range of more than 60 dB for 20 MHz signal bandwidth and OSR of 10 while consuming only 914 μW from 1.8 V power supply. The FoM of the modulator is calculated from two different methods, and excellent performance is achieved for proposed modulator. PMID:25685504

Design of an Input-Parallel Output-Parallel LLC Resonant DC-DC Converter System for DC Microgrids

NASA Astrophysics Data System (ADS)

Juan, Y. L.; Chen, T. R.; Chang, H. M.; Wei, S. E.

2017-11-01

Compared with the centralized power system, the distributed modularized power system is composed of several power modules with lower power capacity to provide a totally enough power capacity for the load demand. Therefore, the current stress of the power components in each module can then be reduced, and the flexibility of system setup is also enhanced. However, the parallel-connected power modules in the conventional system are usually controlled to equally share the power flow which would result in lower efficiency in low loading condition. In this study, a modular power conversion system for DC micro grid is developed with 48 V dc low voltage input and 380 V dc high voltage output. However, in the developed system control strategy, the numbers of power modules enabled to share the power flow is decided according to the output power at lower load demand. Finally, three 350 W power modules are constructed and parallel-connected to setup a modular power conversion system. From the experimental results, compared with the conventional system, the efficiency of the developed power system in the light loading condition is greatly improved. The modularized design of the power system can also decrease the power loss ratio to the system capacity.

Advanced Power Conditioning System

NASA Technical Reports Server (NTRS)

Johnson, N. L.

1971-01-01

The second portion of the advanced power conditioning system development program is reported. Five 100-watt parallel power stages with majority-vote-logic feedback-regulator were breadboarded and tested to the design goals. The input voltage range was 22.1 to 57.4 volts at loads from zero to 500 watts. The maximum input ripple current was 200 mA pk-pk (not including spikes) at 511 watts load; the output voltage was 56V dc with a maximum change of 0.89 volts for all variations of line, load, and temperature; the maximum output ripple was 320 mV pk-pk at 512 watts load (dependent on filter capacitance value); the maximum efficiency was 93.9% at 212 watts and 50V dc input; the minimum efficiency was 87.2% at 80-watt load and 50V dc input; the efficiency was above 90% from 102 watts to 372 watts; the maximum excursion for an 80-watt load change was 2.1 volts with a recovery time of 7 milliseconds; and the unit performed within regulation limits from -20 C to +85 C. During the test sequence, margin tests and failure mode tests were run with no resulting degradation in performance.

Responsivity drop due to conductance modulation in GaN metal-semiconductor-metal Schottky based UV photodetectors on Si(111)

NASA Astrophysics Data System (ADS)

Ravikiran, L.; Radhakrishnan, K.; Dharmarasu, N.; Agrawal, M.; Wang, Zilong; Bruno, Annalisa; Soci, Cesare; Lihuang, Tng; Kian Siong, Ang

2016-09-01

GaN Schottky metal-semiconductor-metal (MSM) UV photodetectors were fabricated on a 600 nm thick GaN layer, grown on 100 mm Si (111) substrate using an ammonia-MBE growth technique. In this report, the effect of device dimensions, applied bias and input power on the linearity of the GaN Schottky-based MSM photodetectors on Si substrate were investigated. Devices with larger interdigitated spacing, ‘S’ of 9.0 μm between the fingers resulted in good linearity and flat responsivity characteristics as a function of input power with an external quantum efficiency (EQE) of ˜33% at an applied bias of 15 V and an input power of 0.8 W m-2. With the decrease of ‘S’ to 3.0 μm, the EQE was found to increase to ˜97%. However, devices showed non linearity and drop in responsivity from flatness at higher input power. Moreover, the position of dropping from flatter responsivity was found to shift to lower powers with increased bias. The drop in the responsivity was attributed to the modulation of conductance in the MSM due to the trapping of electrons at the dislocations, resulting in the formation of depletion regions around them. In devices with lower ‘S’, both the image force reduction and the enhanced collection efficiency increased the photocurrent as well as the charging of the dislocations. This resulted in the increased depletion regions around the dislocations leading to the modulation of conductance and non-linearity.

The impact of frequency on the performance of microwave ablation.

PubMed

Sawicki, James F; Shea, Jacob D; Behdad, Nader; Hagness, Susan C

2017-02-01

The use of higher frequencies in percutaneous microwave ablation (MWA) may offer compelling interstitial antenna design advantages over the 915 MHz and 2.45 GHz frequencies typically employed in current systems. To evaluate the impact of higher frequencies on ablation performance, we conducted a comprehensive computational and experimental study of microwave absorption and tissue heating as a function of frequency. We performed electromagnetic and thermal simulations of MWA in ex vivo and in vivo porcine muscle at discrete frequencies in the 1.9-26 GHz range. Ex vivo ablation experiments were performed in the 1.9-18 GHz range. We tracked the size of the ablation zone across frequency for constant input power and ablation duration. Further, we conducted simulations to investigate antenna feed line heating as a function of frequency, input power, and cable diameter. As the frequency was increased from 1.9 to 26 GHz the resulting ablation zone dimensions decreased in the longitudinal direction while remaining relatively constant in the radial direction; thus at higher frequencies the overall ablation zone was more spherical. However, cable heating at higher frequencies became more problematic for smaller diameter cables at constant input power. Comparably sized ablation zones are achievable well above 1.9 GHz, despite increasingly localised power absorption. Specific absorption rate alone does not accurately predict ablation performance, particularly at higher frequencies where thermal diffusion plays an important role. Cable heating due to ohmic losses at higher frequencies may be controlled through judicious choices of input power and cable diameter.

The Series Connected Buck Boost Regulator Concept for High Efficiency Light Weight DC Voltage Regulation

NASA Technical Reports Server (NTRS)

Birchenough, Arthur G.

2003-01-01

Improvements in the efficiency and size of DC-DC converters have resulted from advances in components, primarily semiconductors, and improved topologies. One topology, which has shown very high potential in limited applications, is the Series Connected Boost Unit (SCBU), wherein a small DC-DC converter output is connected in series with the input bus to provide an output voltage equal to or greater than the input voltage. Since the DC-DC converter switches only a fraction of the power throughput, the overall system efficiency is very high. But this technique is limited to applications where the output is always greater than the input. The Series Connected Buck Boost Regulator (SCBBR) concept extends partial power processing technique used in the SCBU to operation when the desired output voltage is higher or lower than the input voltage, and the implementation described can even operate as a conventional buck converter to operate at very low output to input voltage ratios. This paper describes the operation and performance of an SCBBR configured as a bus voltage regulator providing 50 percent voltage regulation range, bus switching, and overload limiting, operating above 98 percent efficiency. The technique does not provide input-output isolation.

Derated ion thruster design issues

NASA Technical Reports Server (NTRS)

Patterson, Michael J.; Rawlin, Vincent K.

1991-01-01

Preliminary activities to develop and refine a lightweight 30 cm engineering model ion thruster are discussed. The approach is to develop a 'derated' ion thruster capable of performing both auxiliary and primary propulsion roles over an input power range of at least 0.5 to 5.0 kilo-W. Design modifications to a baseline thruster to reduce mass and volume are discussed. Performance data over an order of magnitude input power range are presented, with emphasis on the performance impact of engine throttling. Thruster design modifications to optimize performance over specific power envelopes are discussed. Additionally, lifetime estimates based on wear test measurements are made for the operation envelope of the engine.

Power supply

DOEpatents

Yakymyshyn, Christopher Paul; Hamilton, Pamela Jane; Brubaker, Michael Allen

2007-12-04

A modular, low weight impedance dropping power supply with battery backup is disclosed that can be connected to a high voltage AC source and provide electrical power at a lower voltage. The design can be scaled over a wide range of input voltages and over a wide range of output voltages and delivered power.