Triple voltage dc-to-dc converter and method
Su, Gui-Jia
2008-08-05
A circuit and method of providing three dc voltage buses and transforming power between a low voltage dc converter and a high voltage dc converter, by coupling a primary dc power circuit and a secondary dc power circuit through an isolation transformer; providing the gating signals to power semiconductor switches in the primary and secondary circuits to control power flow between the primary and secondary circuits and by controlling a phase shift between the primary voltage and the secondary voltage. The primary dc power circuit and the secondary dc power circuit each further comprising at least two tank capacitances arranged in series as a tank leg, at least two resonant switching devices arranged in series with each other and arranged in parallel with the tank leg, and at least one voltage source arranged in parallel with the tank leg and the resonant switching devices, said resonant switching devices including power semiconductor switches that are operated by gating signals. Additional embodiments having a center-tapped battery on the low voltage side and a plurality of modules on both the low voltage side and the high voltage side are also disclosed for the purpose of reducing ripple current and for reducing the size of the components.
Center for Applied Linguistics, Washington DC, USA
ERIC Educational Resources Information Center
Sugarman, Julie; Fee, Molly; Donovan, Anne
2015-01-01
The Center for Applied Linguistics (CAL) is a private, nonprofit organization with over 50 years' experience in the application of research on language and culture to educational and societal concerns. CAL carries out its mission to improve communication through better understanding of language and culture by engaging in a variety of projects in…
NASA Technical Reports Server (NTRS)
Schoenfeld, A. D.; Yu, Y.
1973-01-01
Versatile standardized pulse modulation nondissipatively regulated control signal processing circuits were applied to three most commonly used dc to dc power converter configurations: (1) the series switching buck-regulator, (2) the pulse modulated parallel inverter, and (3) the buck-boost converter. The unique control concept and the commonality of control functions for all switching regulators have resulted in improved static and dynamic performance and control circuit standardization. New power-circuit technology was also applied to enhance reliability and to achieve optimum weight and efficiency.
Duckworth, Robert C; Zhang, Yifei; Ha, Tam T; Gouge, Michael J
2011-01-01
In order to predict heat loads in future saturable core fault-current-limiting devices due to ac fringing fields, dynamic resistance in YBCO-coated conductors was measured at 77 K in peak ac fields up to 25 mT at 60 Hz and in dc fields up to 1 T. With the sample orientation set such that the conductor face was either parallel or perpendicular to the ac and dc applied fields, the dynamic resistance was measured at different fractions of the critical current to determine the relationship between the dc transport current and the applied fields. With respect to field orientation, the dynamic resistance for ac fields that were perpendicular to the conductor face was significantly higher than when the ac fields were parallel to the conductor face. It was also observed that the dynamic resistance: (1) increased with increasing fraction of the dc transport current to the critical current, (2) was proportional to the inverse of the critical current, and (3) demonstrated a linear dependence with the applied ac field once a threshold field was exceeded. This functional behavior was consistent with a critical state model for the dynamic resistance, but discrepancies in absolute value of the dynamic resistance suggested that further theoretical development is needed.
Refining Diagnoses: Applying the DC-LD to an Irish Population with Intellectual Disability
ERIC Educational Resources Information Center
Felstrom, A.; Mulryan, N.; Reidy, J.; Staines, M.; Hillery, J.
2005-01-01
Background: The diagnostic criteria for psychiatric disorders for use with adults with learning disabilities/mental retardation (DC-LD) is a diagnostic tool developed in 2001 to improve upon existing classification systems for adults with learning disability. The aim of this study was to apply the classification system described by the DC-LD to a…
NASA Technical Reports Server (NTRS)
Rheinfurth, M. H.; Wilson, H. B.
1991-01-01
The monograph was prepared to give the practicing engineer a clear understanding of dynamics with special consideration given to the dynamic analysis of aerospace systems. It is conceived to be both a desk-top reference and a refresher for aerospace engineers in government and industry. It could also be used as a supplement to standard texts for in-house training courses on the subject. Beginning with the basic concepts of kinematics and dynamics, the discussion proceeds to treat the dynamics of a system of particles. Both classical and modern formulations of the Lagrange equations, including constraints, are discussed and applied to the dynamic modeling of aerospace structures using the modal synthesis technique.
Siemens programmable variable speed DC drives applied to wet and dry expansion engines
Markley, Daniel J.
1997-07-01
This document describes the technical details of the Siemens SIMOREG line of DC variable speed drives as applied to Fermilab wet and dry mechanical expander engines. The expander engines are used throughout the lab in Helium refrigerator installations.
DC to DC power converters and methods of controlling the same
Steigerwald, Robert Louis; Elasser, Ahmed; Sabate, Juan Antonio; Todorovic, Maja Harfman; Agamy, Mohammed
2012-12-11
A power generation system configured to provide direct current (DC) power to a DC link is described. The system includes a first power generation unit configured to output DC power. The system also includes a first DC to DC converter comprising an input section and an output section. The output section of the first DC to DC converter is coupled in series with the first power generation unit. The first DC to DC converter is configured to process a first portion of the DC power output by the first power generation unit and to provide an unprocessed second portion of the DC power output of the first power generation unit to the output section.
Design of piezoelectric transformer for DC/DC converter with stochastic optimization method
NASA Astrophysics Data System (ADS)
Vasic, Dejan; Vido, Lionel
2016-04-01
Piezoelectric transformers were adopted in recent year due to their many inherent advantages such as safety, no EMI problem, low housing profile, and high power density, etc. The characteristics of the piezoelectric transformers are well known when the load impedance is a pure resistor. However, when piezoelectric transformers are used in AC/DC or DC/DC converters, there are non-linear electronic circuits connected before and after the transformer. Consequently, the output load is variable and due to the output capacitance of the transformer the optimal working point change. This paper starts from modeling a piezoelectric transformer connected to a full wave rectifier in order to discuss the design constraints and configuration of the transformer. The optimization method adopted here use the MOPSO algorithm (Multiple Objective Particle Swarm Optimization). We start with the formulation of the objective function and constraints; then the results give different sizes of the transformer and the characteristics. In other word, this method is looking for a best size of the transformer for optimal efficiency condition that is suitable for variable load. Furthermore, the size and the efficiency are found to be a trade-off. This paper proposes the completed design procedure to find the minimum size of PT in need. The completed design procedure is discussed by a given specification. The PT derived from the proposed design procedure can guarantee both good efficiency and enough range for load variation.
A method for simulating a flux-locked DC SQUID
NASA Technical Reports Server (NTRS)
Gutt, G. M.; Kasdin, N. J.; Condron, M. R., II; Muhlfelder, B.; Lockhart, J. M.; Cromar, M. W.
1993-01-01
The authors describe a computationally efficient and accurate method for simulating a dc SQUID's V-Phi (voltage-flux) and I-V characteristics which has proven valuable in evaluating and improving various SQUID readout methods. The simulation of the SQUID is based on fitting of previously acquired data from either a real or a modeled device using the Fourier transform of the V-Phi curve. This method does not predict SQUID behavior, but rather is a way of replicating a known behavior efficiently with portability into various simulation programs such as SPICE. The authors discuss the methods used to simulate the SQUID and the flux-locking control electronics, and present specific examples of this approach. Results include an estimate of the slew rate and linearity of a simple flux-locked loop using a characterized dc SQUID.
METHOD OF APPLYING METALLIC COATINGS
Robinson, J.W.; Eubank, L.D.
1961-08-01
A method for applying a protective coating to a uranium rod is described. The steps include preheating the unanium rod to the coating temperature, placement of the rod between two rotating rollers, pouring a coating metal such as aluminum-silicon in molten form between one of the rotating rollers and the uranium rod, and rotating the rollers continually until the coating is built up to the desired thickness. (AEC)
Self-pumped and double phase conjugation in GaAs with applied dc electric field
NASA Technical Reports Server (NTRS)
Chua, P. L.; Liu, D. T. H.; Cheng, L. J.
1990-01-01
Self-pumped and double phase conjugation are first demonstrated in undoped GaAs with applied dc electric field at 1.06 micron wavelength. Phase-conjugate reflectivities of up to 3 percent and 0.5 percent, respectively, are obtained and other dependences are reported. Reported values of the self-pumped phase-conjugate reflectivity are compared with those of InP.
A broadband reflective filter for applying dc biases to high-Q superconducting microwave cavities
NASA Astrophysics Data System (ADS)
Hao, Yu; Rouxinol, Francisco; Lahaye, Matt
2015-03-01
The integration of dc-bias circuitry into low-loss microwave cavities is an important technical issue for topics in many fields that include research with qubit- and cavity-coupled mechanical system, circuit QED and quantum dynamics of nonlinear systems. The applied potentials or currents serve a variety of functions such as maintaining the operating state of device or establishing tunable electrostatic interactions between devices (for example, in order to couple a nanomechanical resonator to a superconducting qubit to generate and detect quantum states of a mechanical resonator). Here we report a bias-circuit design that utilizes a broadband reflective filter to connect to a high-Q superconducting coplanar waveguide (CPW) cavity. Our design allows us to apply dc-voltages to the center trace of CPW, with negligible changes in loaded quality factors of the fundamental mode. Simulations and measurements of the filter demonstrate insertion loss greater than 20 dB in the range of 3 to 10 GHz. Transmission measurements of the voltage-biased CPW show that loaded quality factors exceeding 105 can be achieved for dc-voltages as high as V = +/- 20V for the cavity operated in the single photon regime. National Science Foundation under Grant No. DMR-1056423 and Grant No. DMR-1312421.
NASA Astrophysics Data System (ADS)
Hanlon, C. J.; Small, A.; Bose, S.; Young, G. S.; Verlinde, J.
2013-12-01
undertaken by DC3 investigators, depending on the scoring method used. Reliability diagram for the algorithmic system used to forecast isolated convective thunderstorms for the DC3 field campaign. The clustering of points around the 45-degree line indicates that the forecasting system is well-calibrated -- a critical requirement for an algorithmic flight decision recommendation system.
NASA Astrophysics Data System (ADS)
Kim, D. W.; Kim, J. G.; Kim, A. R.; Park, M.; Yu, I. K.; Sim, K. D.; Kim, S. H.; Lee, S. J.; Cho, J. W.; Won, Y. J.
2010-11-01
The authors calculated the loss of the High Temperature Superconducting (HTS) model cable using Norris ellipse formula, and measured the loss of the model cable experimentally. Two kinds of measuring method are used. One is the electrical method, and the other is the calorimetric method. The electrical method can be used only in AC condition. But the calorimetric method can be used in both AC and DC bias conditions. In order to propose an effective measuring approach for Ripple Dependent Loss (RDL) under DC bias condition using the calorimetric method, Bismuth Strontium Calcium Copper Oxide (BSCCO) wires were used for the HTS model cable, and the SUS tapes were used as a heating tape to make the same pattern of the temperature profiles as in the electrical method without the transport current. The temperature-loss relations were obtained by the electrical method, and then applied to the calorimetric method by which the RDL under DC bias condition was well estimated.
Effects of applied dc radial electric fields on particle transport in a bumpy torus plasma
NASA Technical Reports Server (NTRS)
Roth, J. R.
1978-01-01
The influence of applied dc radial electric fields on particle transport in a bumpy torus plasma is studied. The plasma, magnetic field, and ion heating mechanism are operated in steady state. Ion kinetic temperature is more than a factor of ten higher than electron temperature. The electric fields raise the ions to energies on the order of kilovolts and then point radially inward or outward. Plasma number density profiles are flat or triangular across the plasma diameter. It is suggested that the radial transport processes are nondiffusional and dominated by strong radial electric fields. These characteristics are caused by the absence of a second derivative in the density profile and the flat electron temperature profiles. If the electric field acting on the minor radius of the toroidal plasma points inward, plasma number density and confinement time are increased.
Circuit and Method for Communication Over DC Power Line
NASA Technical Reports Server (NTRS)
Krasowski, Michael J.; Prokop, Norman F.
2007-01-01
A circuit and method for transmitting and receiving on-off-keyed (OOK) signals with fractional signal-to-noise ratios uses available high-temperature silicon- on-insulator (SOI) components to move computational, sensing, and actuation abilities closer to high-temperature or high-ionizing radiation environments such as vehicle engine compartments, deep-hole drilling environments, industrial control and monitoring of processes like smelting, and operations near nuclear reactors and in space. This device allows for the networking of multiple, like nodes to each other and to a central processor. It can do this with nothing more than the already in-situ power wiring of the system. The device s microprocessor allows it to make intelligent decisions within the vehicle operational loop and to effect control outputs to its associated actuators. The figure illustrates how each node converts digital serial data to OOK 18-kHz in transmit mode and vice-versa in receive mode; though operations at lower frequencies or up to a megahertz are within reason using this method and these parts. This innovation s technique modulates a DC power bus with millivolt-level signals through a MOSFET (metal oxide semiconductor field effect transistor) and resistor by OOK. It receives and demodulates this signal from the DC power bus through capacitive coupling at high temperature and in high ionizing radiation environments. The demodulation of the OOK signal is accomplished by using an asynchronous quadrature detection technique realized by a quasi-discrete Fourier transform through use of the quadrature components (0 and 90 phases) of the carrier frequency as generated by the microcontroller and as a function of the selected crystal frequency driving its oscillator. The detected signal is rectified using an absolute-value circuit containing no diodes (diodes being non-operational at high temperatures), and only operational amplifiers. The absolute values of the two phases of the received signal
Body edge delineation in 2D DC resistivity imaging using differential method
NASA Astrophysics Data System (ADS)
Susanto, Kusnahadi; Fitrah Bahari, Mohammad
2016-01-01
DC resistivity is widely used to identify the kind of rock and the lithology contact. However, the image resulting from resistivity processing is shown in a contour image. There is be a problem to interpret where the edge of body location is. This study uses differential method to delineate the edge of body in DC resistivity contour. This method was applied to the boundary between gravel and underlying clay layer. The first and the second order differential method is applied to the delineation of lithology contact. The profiling curve has to be sliced and extracted from the resistivity contour before the differential method can be used. The spectral analysis shows the frequency and wavenumber of the profiling curve used to make gridding. The slicing process was conducted horizontally and vertically in order to get the mesh size which will be used in the differential method. The second order differential, the Laplace operator, is able to show the edge of body more clearly than the first order differential and shows the contact between gravel and clay.
Modelling of stress fields during LFEM DC casting of aluminium billets by a meshless method
NASA Astrophysics Data System (ADS)
Mavrič, B.; Šarler, B.
2015-06-01
Direct Chill (DC) casting of aluminium alloys is a widely established technology for efficient production of aluminium billets and slabs. The procedure is being further improved by the application of Low Frequency Electromagnetic Field (LFEM) in the area of the mold. Novel LFEM DC processing technique affects many different phenomena which occur during solidification, one of them being the stresses and deformations present in the billet. These quantities can have a significant effect on the quality of the cast piece, since they impact porosity, hot-tearing and cold cracking. In this contribution a novel local radial basis function collocation method (LRBFCM) is successfully applied to the problem of stress field calculation during the stationary state of DC casting of aluminium alloys. The formulation of the method is presented in detail, followed by the presentation of the tackled physical problem. The model describes the deformations of linearly elastic, inhomogeneous isotropic solid with a given temperature field. The temperature profile is calculated using the in-house developed heat and mass transfer model. The effects of low frequency EM casting process parameters on the vertical, circumferential and radial stress and on the deformation of billet surface are presented. The application of the LFEM appears to decrease the amplitudes of the tensile stress occurring in the billet.
Synthesis of silicon nanotubes by DC arc plasma method
Tank, C. M.; Bhoraskar, S. V.; Mathe, V. L.
2012-06-05
Plasma synthesis is a novel technique of synthesis of nanomaterials as they provide high rate of production and promote metastable reactions. Very thin walled silicon nanotubes were synthesized in a DC direct arc thermal plasma reactor. The effect of parameters of synthesis i.e. arc current and presence of hydrogen on the morphology of Si nanoparticles is reported. Silicon nanotubes were characterized by Transmission Electron Microscopy (TEM), Local Energy Dispersive X-ray analysis (EDAX), and Scanning Tunneling Microscopy (STM).
NASA Astrophysics Data System (ADS)
Hanlon, Christopher J.; Small, Arthur A.; Bose, Satyajit; Young, George S.; Verlinde, Johannes
2014-10-01
Automated decision systems have shown the potential to increase data yields from field experiments in atmospheric science. The present paper describes the construction and performance of a flight decision system designed for a case in which investigators pursued multiple, potentially competing objectives. The Deep Convective Clouds and Chemistry (DC3) campaign in 2012 sought in situ airborne measurements of isolated deep convection in three study regions: northeast Colorado, north Alabama, and a larger region extending from central Oklahoma through northwest Texas. As they confronted daily flight launch decisions, campaign investigators sought to achieve two mission objectives that stood in potential tension to each other: to maximize the total amount of data collected while also collecting approximately equal amounts of data from each of the three study regions. Creating an automated decision system involved understanding how investigators would themselves negotiate the trade-offs between these potentially competing goals, and representing those preferences formally using a utility function that served to rank-order the perceived value of alternative data portfolios. The decision system incorporated a custom-built method for generating probabilistic forecasts of isolated deep convection and estimated climatologies calibrated to historical observations. Monte Carlo simulations of alternative future conditions were used to generate flight decision recommendations dynamically consistent with the expected future progress of the campaign. Results show that a strict adherence to the recommendations generated by the automated system would have boosted the data yield of the campaign by between 10 and 57%, depending on the metrics used to score success, while improving portfolio balance.
Test case set generation method on MC/DC based on binary tree
NASA Astrophysics Data System (ADS)
Wang, Jun-jie; Zhang, Bo; Chen, Yuan
2013-03-01
Exploring efficient, reliable test case design methods has been tester pursuit of the goal. Along with the aerospace software logic complexity of improving and software scale enlarging, this requirement also gets more compelling. Test case design techniques suited for MC/DC improved test case design efficiency, increase the test coverage. It is suitable to test the software that logical relationship is complicated comparatively. Some software test tools provide the function to calculate the test coverage. And it can assess the test cases whether on the MC/DC or not. But the software tester needs the reverse thinking. The paper puts forward that design the test case by Unique-cause and Masking approach. And it proposes automatic generation method of test case on MC/DC. It improved the efficiency and correctness of generation the test case set on DC/DC.
Su, Gui-Jia
2003-06-10
A multilevel DC link inverter and method for improving torque response and current regulation in permanent magnet motors and switched reluctance motors having a low inductance includes a plurality of voltage controlled cells connected in series for applying a resulting dc voltage comprised of one or more incremental dc voltages. The cells are provided with switches for increasing the resulting applied dc voltage as speed and back EMF increase, while limiting the voltage that is applied to the commutation switches to perform PWM or dc voltage stepping functions, so as to limit current ripple in the stator windings below an acceptable level, typically 5%. Several embodiments are disclosed including inverters using IGBT's, inverters using thyristors. All of the inverters are operable in both motoring and regenerating modes.
Three dimensional finite element methods: Their role in the design of DC accelerator systems
Podaru, Nicolae C.; Gottdang, A.; Mous, D. J. W.
2013-04-19
High Voltage Engineering has designed, built and tested a 2 MV dual irradiation system that will be applied for radiation damage studies and ion beam material modification. The system consists of two independent accelerators which support simultaneous proton and electron irradiation (energy range 100 keV - 2 MeV) of target sizes of up to 300 Multiplication-Sign 300 mm{sup 2}. Three dimensional finite element methods were used in the design of various parts of the system. The electrostatic solver was used to quantify essential parameters of the solid-state power supply generating the DC high voltage. The magnetostatic solver and ray tracing were used to optimize the electron/ion beam transport. Close agreement between design and measurements of the accelerator characteristics as well as beam performance indicate the usefulness of three dimensional finite element methods during accelerator system design.
Three dimensional finite element methods: Their role in the design of DC accelerator systems
NASA Astrophysics Data System (ADS)
Podaru, Nicolae C.; Gottdang, A.; Mous, D. J. W.
2013-04-01
High Voltage Engineering has designed, built and tested a 2 MV dual irradiation system that will be applied for radiation damage studies and ion beam material modification. The system consists of two independent accelerators which support simultaneous proton and electron irradiation (energy range 100 keV - 2 MeV) of target sizes of up to 300 × 300 mm2. Three dimensional finite element methods were used in the design of various parts of the system. The electrostatic solver was used to quantify essential parameters of the solid-state power supply generating the DC high voltage. The magnetostatic solver and ray tracing were used to optimize the electron/ion beam transport. Close agreement between design and measurements of the accelerator characteristics as well as beam performance indicate the usefulness of three dimensional finite element methods during accelerator system design.
Method to eliminate flux linkage DC component in load transformer for static transfer switch.
He, Yu; Mao, Chengxiong; Lu, Jiming; Wang, Dan; Tian, Bing
2014-01-01
Many industrial and commercial sensitive loads are subject to the voltage sags and interruptions. The static transfer switch (STS) based on the thyristors is applied to improve the power quality and reliability. However, the transfer will result in severe inrush current in the load transformer, because of the DC component in the magnetic flux generated in the transfer process. The inrush current which is always 2 ~ 30 p.u. can cause the disoperation of relay protective devices and bring potential damage to the transformer. The way to eliminate the DC component is to transfer the related phases when the residual flux linkage of the load transformer and the prospective flux linkage of the alternate source are equal. This paper analyzes how the flux linkage of each winding in the load transformer changes in the transfer process. Based on the residual flux linkage when the preferred source is completely disconnected, the method to calculate the proper time point to close each phase of the alternate source is developed. Simulation and laboratory experiments results are presented to show the effectiveness of the transfer method. PMID:25133255
Method to Eliminate Flux Linkage DC Component in Load Transformer for Static Transfer Switch
2014-01-01
Many industrial and commercial sensitive loads are subject to the voltage sags and interruptions. The static transfer switch (STS) based on the thyristors is applied to improve the power quality and reliability. However, the transfer will result in severe inrush current in the load transformer, because of the DC component in the magnetic flux generated in the transfer process. The inrush current which is always 2~30 p.u. can cause the disoperation of relay protective devices and bring potential damage to the transformer. The way to eliminate the DC component is to transfer the related phases when the residual flux linkage of the load transformer and the prospective flux linkage of the alternate source are equal. This paper analyzes how the flux linkage of each winding in the load transformer changes in the transfer process. Based on the residual flux linkage when the preferred source is completely disconnected, the method to calculate the proper time point to close each phase of the alternate source is developed. Simulation and laboratory experiments results are presented to show the effectiveness of the transfer method. PMID:25133255
[Montessori method applied to dementia - literature review].
Brandão, Daniela Filipa Soares; Martín, José Ignacio
2012-06-01
The Montessori method was initially applied to children, but now it has also been applied to people with dementia. The purpose of this study is to systematically review the research on the effectiveness of this method using Medical Literature Analysis and Retrieval System Online (Medline) with the keywords dementia and Montessori method. We selected lo studies, in which there were significant improvements in participation and constructive engagement, and reduction of negative affects and passive engagement. Nevertheless, systematic reviews about this non-pharmacological intervention in dementia rate this method as weak in terms of effectiveness. This apparent discrepancy can be explained because the Montessori method may have, in fact, a small influence on dimensions such as behavioral problems, or because there is no research about this method with high levels of control, such as the presence of several control groups or a double-blind study. PMID:23155599
The averaging method in applied problems
NASA Astrophysics Data System (ADS)
Grebenikov, E. A.
1986-04-01
The totality of methods, allowing to research complicated non-linear oscillating systems, named in the literature "averaging method" has been given. THe author is describing the constructive part of this method, or a concrete form and corresponding algorithms, on mathematical models, sufficiently general , but built on concrete problems. The style of the book is that the reader interested in the Technics and algorithms of the asymptotic theory of the ordinary differential equations, could solve individually such problems. For specialists in the area of applied mathematics and mechanics.
System and Method for Determining Rate of Rotation Using Brushless DC Motor
NASA Technical Reports Server (NTRS)
Howard, David E. (Inventor); Smith, Dennis A. (Inventor)
2000-01-01
A system and method are provided for measuring rate of rotation. A brushless DC motor is rotated and produces a back electromagnetic force (emf) on each winding thereof. Each winding's back-emf is squared. The squared outputs associated with each winding are combined, with the square root being taken of such combination, to produce a DC output proportional only to the rate of rotation of the motor's shaft.
A new method for speed control of a DC motor using magnetorheological clutch
NASA Astrophysics Data System (ADS)
Nguyen, Quoc Hung; Choi, Seung-Bok
2014-03-01
In this research, a new method to control speed of DC motor using magnetorheological (MR) clutch is proposed and realized. Firstly, the strategy of a DC motor speed control using MR clutch is proposed. The MR clutch configuration is then proposed and analyzed based on Bingham-plastic rheological model of MR fluid. An optimal designed of the MR clutch is then studied to find out the optimal geometric dimensions of the clutch that can transform a required torque with minimum mass. A prototype of the optimized MR clutch is then manufactured and its performance characteristics are experimentally investigated. A DC motor speed control system featuring the optimized MR clutch is designed and manufactured. A PID controller is then designed to control the output speed of the system. In order to evaluate the effectiveness of the proposed DC motor speed control system, experimental results of the system such as speed tracking performance are obtained and presented with discussions.
Investigation of an innovative method for DC flow suppression of double-inlet pulse tube coolers
NASA Astrophysics Data System (ADS)
Hu, J. Y.; Luo, E. C.; Wu, Z. H.; Dai, W.; Zhu, S. L.
2007-05-01
The use of double-inlet mode in the pulse tube cooler opens up a possibility of DC flow circulating around the regenerator and the pulse tube. The DC flow sometimes deteriorates the performance of the cryocooler because such a steady flow adds an unwanted thermal load to the cold heat exchanger. It seems that this problem is still not well solved although a lot of effort has been made. Here we introduce a membrane-barrier method for DC flow suppression in double-inlet pulse tube coolers. An elastic membrane is installed between the pulse tube cooler inlet and the double-inlet valve to break the closed-loop flow path of DC flow. The membrane is acoustically transparent, but would block the DC flow completely. Thus the DC flow is thoroughly suppressed and the merit of double-inlet mode is remained. With this method, a temperature reduction of tens of Kelvin was obtained in our single-stage pulse tube cooler and the lowest temperature reached 29.8 K.
Entropy viscosity method applied to Euler equations
Delchini, M. O.; Ragusa, J. C.; Berry, R. A.
2013-07-01
The entropy viscosity method [4] has been successfully applied to hyperbolic systems of equations such as Burgers equation and Euler equations. The method consists in adding dissipative terms to the governing equations, where a viscosity coefficient modulates the amount of dissipation. The entropy viscosity method has been applied to the 1-D Euler equations with variable area using a continuous finite element discretization in the MOOSE framework and our results show that it has the ability to efficiently smooth out oscillations and accurately resolve shocks. Two equations of state are considered: Ideal Gas and Stiffened Gas Equations Of State. Results are provided for a second-order time implicit schemes (BDF2). Some typical Riemann problems are run with the entropy viscosity method to demonstrate some of its features. Then, a 1-D convergent-divergent nozzle is considered with open boundary conditions. The correct steady-state is reached for the liquid and gas phases with a time implicit scheme. The entropy viscosity method correctly behaves in every problem run. For each test problem, results are shown for both equations of state considered here. (authors)
Novel ac Heating-dc Detection Method for Active Thermoelectric Scanning Thermal Microscopy
NASA Astrophysics Data System (ADS)
Miao, Tingting; Ma, Weigang; Zhang, Xing
2015-11-01
A novel and reliable ac heating-dc detection method is developed for active thermoelectric scanning thermal microscopy, which can map out local thermal property imaging by point-heating and point-sensing with nanoscale spatial resolution. The thermoelectric probe is electrically heated by an ac current, and the corresponding dc thermoelectric voltage is detected. Using the measured dc voltage, the temperature information can be extracted with the known Seebeck coefficient of the thermoelectric probe. The validity and accuracy of this method have been verified by a 25.4 \\upmu m thick K-type thermocouple by both experiment and numerical simulation in high vacuum and in air. The experimental results show that the proposed method is reliable and convenient to monitor the temperature of the junction.
NASA Technical Reports Server (NTRS)
Mendrek, M. J.; Higgins, R. H.; Danford, M. D.
1988-01-01
To investigate metal surface corrosion and the breakdown of metal protective coatings, the ac impedance method is applied to six systems of primer coated and primer topcoated 4130 steel. Two primers were used: a zinc-rich epoxy primer and a red lead oxide epoxy primer. The epoxy-polyamine topcoat was used in four of the systems. The EG and G-PARC Model 368 ac impedance measurement system, along with dc measurements with the same system using the polarization resistance method, were used to monitor changing properties of coated 4230 steel disks immersed in 3.5 percent NaCl solutions buffered at pH 5.4 over periods of 40 to 60 days. The corrosion system can be represented by an electronic analog called an equivalent circuit consisting of resistors and capacitors in specific arrangements. This equivalent circuit parallels the impedance behavior of the corrosion system during a frequency scan. Values for the resistors and capacitors, that can be assigned in the equivalent circuit following a least-squares analysis of the data, describe changes that occur on the corroding metal surface and in the protective coatings. Two equivalent circuits have been determined that predict the correct Bode phase and magnitude of the experimental sample at different immersion times. The dc corrosion current density data are related to equivalent circuit element parameters. Methods for determining corrosion rate with ac impedance parameters are verified by the dc method.
A novel method for simulation of brushless DC motor servo-control system based on MATLAB
NASA Astrophysics Data System (ADS)
Tao, Keyan; Yan, Yingmin
2006-11-01
This paper provides a research about the simulation of brush-less DC motor (BLDCM) servo control system. Based on the mathematical model of Brush-less DC motor (BLDCM), built the system simulation model with the MATLAB software. When the system model is made, the isolated functional blocks, such as BLDCM block, the rotor's position detection block, change-phase logic block etc. have been modeled. By the organic combination of these blocks, the model of BLDCM can be established easily. The reasonability and validity have been testified by the simulation results and this novel method offers a new thought way for designing and debugging actual motors.
New Current Control Method of DC Power Supply for Magnetic Perturbation Coils on J-TEXT
NASA Astrophysics Data System (ADS)
Zeng, Wubing; Ding, Yonghua; Yi, Bin; Xu, Hangyu; Rao, Bo; Zhang, Ming; Liu, Minghai
2014-11-01
In order to advance the research on suppressing tearing modes and driving plasma rotation, a DC power supply (PS) system has been developed for dynamic resonant magnetic perturbation (DRMP) coils and applied in the J-TEXT experiment. To enrich experimental phenomena in the J-TEXT tokamak, applying the circulating current four-quadrant operation mode in the DRMP DC PS system is proposed. By using the circulating current four-quadrant operation, DRMP coils can be smoothly controlled without the dead-time when the current polarity reverses. Essential circuit analysis, control optimization and simulation of desired scenarios have been performed for normal current. Relevant simulation and test results are also presented.
Quasilinearization method applied to multidimensional quantum tunneling
NASA Astrophysics Data System (ADS)
Razavy, M.; Cote, Vincent J.
1994-04-01
We apply the quasilinearization method of Bellman and Kalaba [Quasilinearization and Nonlinear Boundary-Value Problems (Elsevier, New York, 1965)] to find approximate solutions for the multidimensional quantum tunneling for separable as well as nonseparable wave equations. By introducing the idea of the complex ``semiclassical trajectory'' which is valid for the motion over and under the barrier, and which, in the proper limit, reduces to the real classical trajectory in the allowed region, we obtain an eigenvalue equation for the characteristic wave numbers. This eigenvalue equation is similar to the corresponding equation obtained from the WKB approximation and yields complex eigenvalues with negative imaginary parts. When the barrier changes very rapidly as a function of the radial distance, we can replace the concept of the semiclassical trajectory, which may not be applicable in this case, by the concept of a complex ``quantum trajectory.'' The trajectory defined either way depends on a constant of integration, and by minimizing the action with respect to this constant we can obtain the minimum escape path. The case of two-dimensional tunneling is discussed as an example of this method.
Adaptable DC offset correction
NASA Technical Reports Server (NTRS)
Golusky, John M. (Inventor); Muldoon, Kelly P. (Inventor)
2009-01-01
Methods and systems for adaptable DC offset correction are provided. An exemplary adaptable DC offset correction system evaluates an incoming baseband signal to determine an appropriate DC offset removal scheme; removes a DC offset from the incoming baseband signal based on the appropriate DC offset scheme in response to the evaluated incoming baseband signal; and outputs a reduced DC baseband signal in response to the DC offset removed from the incoming baseband signal.
Forward modeling of marine DC resistivity method for a layered anisotropic earth
NASA Astrophysics Data System (ADS)
Yin, Chang-Chun; Zhang, Ping; Cai, Jing
2016-06-01
Since the ocean bottom is a sedimentary environment wherein stratification is well developed, the use of an anisotropic model is best for studying its geology. Beginning with Maxwell's equations for an anisotropic model, we introduce scalar potentials based on the divergence-free characteristic of the electric and magnetic (EM) fields. We then continue the EM fields down into the deep earth and upward into the seawater and couple them at the ocean bottom to the transmitting source. By studying both the DC apparent resistivity curves and their polar plots, we can resolve the anisotropy of the ocean bottom. Forward modeling of a high-resistivity thin layer in an anisotropic half-space demonstrates that the marine DC resistivity method in shallow water is very sensitive to the resistive reservoir but is not influenced by airwaves. As such, it is very suitable for oil and gas exploration in shallowwater areas but, to date, most modeling algorithms for studying marine DC resistivity are based on isotropic models. In this paper, we investigate one-dimensional anisotropic forward modeling for marine DC resistivity method, prove the algorithm to have high accuracy, and thus provide a theoretical basis for 2D and 3D forward modeling.
Method and apparatus for generating radiation utilizing DC to AC conversion with a conductive front
Dawson, John M.; Mori, Warren B.; Lai, Chih-Hsiang; Katsouleas, Thomas C.
1998-01-01
Method and apparatus for generating radiation of high power, variable duration and broad tunability over several orders of magnitude from a laser-ionized gas-filled capacitor array. The method and apparatus convert a DC electric field pattern into a coherent electromagnetic wave train when a relativistic ionization front passes between the capacitor plates. The frequency and duration of the radiation is controlled by the gas pressure and capacitor spacing.
Method and apparatus for generating radiation utilizing DC to AC conversion with a conductive front
Dawson, J.M.; Mori, W.B.; Lai, C.H.; Katsouleas, T.C.
1998-07-14
Method and apparatus ar disclosed for generating radiation of high power, variable duration and broad tunability over several orders of magnitude from a laser-ionized gas-filled capacitor array. The method and apparatus convert a DC electric field pattern into a coherent electromagnetic wave train when a relativistic ionization front passes between the capacitor plates. The frequency and duration of the radiation is controlled by the gas pressure and capacitor spacing. 4 figs.
Applied Mathematical Methods in Theoretical Physics
NASA Astrophysics Data System (ADS)
Masujima, Michio
2005-04-01
All there is to know about functional analysis, integral equations and calculus of variations in a single volume. This advanced textbook is divided into two parts: The first on integral equations and the second on the calculus of variations. It begins with a short introduction to functional analysis, including a short review of complex analysis, before continuing a systematic discussion of different types of equations, such as Volterra integral equations, singular integral equations of Cauchy type, integral equations of the Fredholm type, with a special emphasis on Wiener-Hopf integral equations and Wiener-Hopf sum equations. After a few remarks on the historical development, the second part starts with an introduction to the calculus of variations and the relationship between integral equations and applications of the calculus of variations. It further covers applications of the calculus of variations developed in the second half of the 20th century in the fields of quantum mechanics, quantum statistical mechanics and quantum field theory. Throughout the book, the author presents over 150 problems and exercises -- many from such branches of physics as quantum mechanics, quantum statistical mechanics, and quantum field theory -- together with outlines of the solutions in each case. Detailed solutions are given, supplementing the materials discussed in the main text, allowing problems to be solved making direct use of the method illustrated. The original references are given for difficult problems. The result is complete coverage of the mathematical tools and techniques used by physicists and applied mathematicians Intended for senior undergraduates and first-year graduates in science and engineering, this is equally useful as a reference and self-study guide.
Study of New Start Method for Position Sensorless Brushless DC Motor
NASA Astrophysics Data System (ADS)
Kawabata, Yukio; Endo, Tsunehiro; Takakura, Yuhachi; Ishii, Makoto
The position sensor-less drive technique based on the back electromotive force (EMF) has been widely used for brush-less DC motor drives. However, it is impossible to detect the rotor position at low-speed by using this technique. Therefore, the motor must be accelerated by the open loop based synchronous drive up to the middle speed. The open loop based synchronous drive extremely influences the motor performance. The torque pulsation and the over current can be occurred by using that. This paper proposes a new start method for the brush-less DC motors. In this method, the rotor position can be detected the moment the motor is driven. As a result, the open loop based synchronous drive can be eliminated, rapid acceleration and high performance of the motor drives are achieved. Effectiveness of the proposed method is shown by experimental results.
An IPOT meshless method using DC PSE approximation for fluid flow equations in 2D and 3D geometries
NASA Astrophysics Data System (ADS)
Bourantas, G. C.; Loukopoulos, V. C.; Skouras, E. D.; Burganos, V. N.; Nikiforidis, G. C.
2016-06-01
Navier-Stokes (N-S) equations, in their primitive variable (u-v-p) formulation, are numerically solved using the Implicit Potential (IPOT) numerical scheme in the context of strong form Meshless Point Collocation (MPC) method. The unknown field functions are computed using the Discretization Correction Particle Strength Exchange (DC PSE) approximation method. The latter makes use of discrete moment conditions to derive the operator kernels, which leads to low condition number for the moment matrix compared to other meshless interpolation methods and increased stability for the numerical solution. The proposed meshless scheme is applied on 2D and 3D spatial domains, using uniform or irregular set of nodes to represent the domain. The numerical results obtained are compared against those obtained using well-established methods.
Method of measuring the dc electric field and other tokamak parameters
Fisch, Nathaniel J.; Kirtz, Arnold H.
1992-01-01
A method including externally imposing an impulsive momentum-space flux to perturb hot tokamak electrons thereby producing a transient synchrotron radiation signal, in frequency-time space, and the inference, using very fast algorithms, of plasma parameters including the effective ion charge state Z.sub.eff, the direction of the magnetic field, and the position and width in velocity space of the impulsive momentum-space flux, and, in particular, the dc toroidal electric field.
NASA Astrophysics Data System (ADS)
Boughariou, F.; Chouikhi, S.; Kallel, A.; Belgaroui, E.
2015-12-01
In this paper, we present a new theoretical and numerical formulation for the electrical and thermal breakdown phenomena, induced by charge packet dynamics, in low-density polyethylene (LDPE) insulating film under dc high applied field. The theoretical physical formulation is composed by the equations of bipolar charge transport as well as by the thermo-electric coupled equation associated for the first time in modeling to the bipolar transport problem. This coupled equation is resolved by the finite-element numerical model. For the first time, all bipolar transport results are obtained under non-uniform temperature distributions in the sample bulk. The principal original results show the occurring of very sudden abrupt increase in local temperature associated to a very sharp increase in external and conduction current densities appearing during the steady state. The coupling between these electrical and thermal instabilities reflects physically the local coupling between electrical conduction and thermal joule effect. The results of non-uniform temperature distributions induced by non-uniform electrical conduction current are also presented for several times. According to our formulation, the strong injection current is the principal factor of the electrical and thermal breakdown of polymer insulating material. This result is shown in this work. Our formulation is also validated experimentally.
Bootstrapping Methods Applied for Simulating Laboratory Works
ERIC Educational Resources Information Center
Prodan, Augustin; Campean, Remus
2005-01-01
Purpose: The aim of this work is to implement bootstrapping methods into software tools, based on Java. Design/methodology/approach: This paper presents a category of software e-tools aimed at simulating laboratory works and experiments. Findings: Both students and teaching staff use traditional statistical methods to infer the truth from sample…
Perturbation approach applied to modal diffraction methods.
Bischoff, Joerg; Hehl, Karl
2011-05-01
Eigenvalue computation is an important part of many modal diffraction methods, including the rigorous coupled wave approach (RCWA) and the Chandezon method. This procedure is known to be computationally intensive, accounting for a large proportion of the overall run time. However, in many cases, eigenvalue information is already available from previous calculations. Some of the examples include adjacent slices in the RCWA, spectral- or angle-resolved scans in optical scatterometry and parameter derivatives in optimization. In this paper, we present a new technique that provides accurate and highly reliable solutions with significant improvements in computational time. The proposed method takes advantage of known eigensolution information and is based on perturbation method. PMID:21532698
Applying Human Computation Methods to Information Science
ERIC Educational Resources Information Center
Harris, Christopher Glenn
2013-01-01
Human Computation methods such as crowdsourcing and games with a purpose (GWAP) have each recently drawn considerable attention for their ability to synergize the strengths of people and technology to accomplish tasks that are challenging for either to do well alone. Despite this increased attention, much of this transformation has been focused on…
Surface Analytical Methods Applied to Magnesium Corrosion.
Dauphin-Ducharme, Philippe; Mauzeroll, Janine
2015-08-01
Understanding magnesium alloy corrosion is of primary concern, and scanning probe techniques are becoming key analytical characterization methods for that purpose. This Feature presents recent trends in this field as the progressive substitution of steel and aluminum car components by magnesium alloys to reduce the overall weight of vehicles is an irreversible trend. PMID:25826577
METHOD OF APPLYING COPPER COATINGS TO URANIUM
Gray, A.G.
1959-07-14
A method is presented for protecting metallic uranium, which comprises anodic etching of the uranium in an aqueous phosphoric acid solution containing chloride ions, cleaning the etched uranium in aqueous nitric acid solution, promptly electro-plating the cleaned uranium in a copper electro-plating bath, and then electro-plating thereupon lead, tin, zinc, cadmium, chromium or nickel from an aqueous electro-plating bath.
Metal alloy coatings and methods for applying
Merz, Martin D.; Knoll, Robert W.
1991-01-01
A method of coating a substrate comprises plasma spraying a prealloyed feed powder onto a substrate, where the prealloyed feed powder comprises a significant amount of an alloy of stainless steel and at least one refractory element selected from the group consisting of titanium, zirconium, hafnium, niobium, tantalum, molybdenum, and tungsten. The plasma spraying of such a feed powder is conducted in an oxygen containing atmosphere and forms an adherent, corrosion resistant, and substantially homogenous metallic refractory alloy coating on the substrate.
Applying New Methods to Diagnose Coral Diseases
Kellogg, Christina A.; Zawada, David G.
2009-01-01
Coral disease, one of the major causes of reef degradation and coral death, has been increasing worldwide since the 1970s, particularly in the Caribbean. Despite increased scientific study, simple questions about the extent of disease outbreaks and the causative agents remain unanswered. A component of the U.S. Geological Survey Coral Reef Ecosystem STudies (USGS CREST) project is focused on developing and using new methods to approach the complex problem of coral disease.
METHOD OF APPLYING NICKEL COATINGS ON URANIUM
Gray, A.G.
1959-07-14
A method is presented for protectively coating uranium which comprises etching the uranium in an aqueous etching solution containing chloride ions, electroplating a coating of nickel on the etched uranium and heating the nickel plated uranium by immersion thereof in a molten bath composed of a material selected from the group consisting of sodium chloride, potassium chloride, lithium chloride, and mixtures thereof, maintained at a temperature of between 700 and 800 deg C, for a time sufficient to alloy the nickel and uranium and form an integral protective coating of corrosion-resistant uranium-nickel alloy.
ALLOY COATINGS AND METHOD OF APPLYING
Eubank, L.D.; Boller, E.R.
1958-08-26
A method for providing uranium articles with a pro tective coating by a single dip coating process is presented. The uranium article is dipped into a molten zinc bath containing a small percentage of aluminum. The resultant product is a uranium article covered with a thin undercoat consisting of a uranium-aluminum alloy with a small amount of zinc, and an outer layer consisting of zinc and aluminum. The article may be used as is, or aluminum sheathing may then be bonded to the aluminum zinc outer layer.
Scanning methods applied to bitemark analysis
NASA Astrophysics Data System (ADS)
Bush, Peter J.; Bush, Mary A.
2010-06-01
The 2009 National Academy of Sciences report on forensics focused criticism on pattern evidence subdisciplines in which statements of unique identity are utilized. One principle of bitemark analysis is that the human dentition is unique to the extent that a perpetrator may be identified based on dental traits in a bitemark. Optical and electron scanning methods were used to measure dental minutia and to investigate replication of detail in human skin. Results indicated that being a visco-elastic substrate, skin effectively reduces the resolution of measurement of dental detail. Conclusions indicate caution in individualization statements.
Optimization methods applied to hybrid vehicle design
NASA Technical Reports Server (NTRS)
Donoghue, J. F.; Burghart, J. H.
1983-01-01
The use of optimization methods as an effective design tool in the design of hybrid vehicle propulsion systems is demonstrated. Optimization techniques were used to select values for three design parameters (battery weight, heat engine power rating and power split between the two on-board energy sources) such that various measures of vehicle performance (acquisition cost, life cycle cost and petroleum consumption) were optimized. The apporach produced designs which were often significant improvements over hybrid designs already reported on in the literature. The principal conclusions are as follows. First, it was found that the strategy used to split the required power between the two on-board energy sources can have a significant effect on life cycle cost and petroleum consumption. Second, the optimization program should be constructed so that performance measures and design variables can be easily changed. Third, the vehicle simulation program has a significant effect on the computer run time of the overall optimization program; run time can be significantly reduced by proper design of the types of trips the vehicle takes in a one year period. Fourth, care must be taken in designing the cost and constraint expressions which are used in the optimization so that they are relatively smooth functions of the design variables. Fifth, proper handling of constraints on battery weight and heat engine rating, variables which must be large enough to meet power demands, is particularly important for the success of an optimization study. Finally, the principal conclusion is that optimization methods provide a practical tool for carrying out the design of a hybrid vehicle propulsion system.
Point of collapse and continuation methods for large ac/dc systems
Canizares, C.A. ); Alvarado, F.L. )
1993-02-01
This paper describes the implementation of both Point of Collapse (PoC) methods and continuation methods for the computation of voltage collapse points (saddle-node bifurcations) in large ac/dc systems. A comparison of the performance of these methods is presented for real systems of up to 2,158 buses. The paper discusses computational details of the implementation of the PoC and continuation methods, and the unique challenges encountered due to the presence of high voltage direct current (HVDC) transmission, area interchange power control regulating transformers, and voltage and reactive power limits. The characteristics of a robust PoC power flow program are presented, and its application to detection and solution of voltage stability problems is demonstrated.
Reflections on Mixing Methods in Applied Linguistics Research
ERIC Educational Resources Information Center
Hashemi, Mohammad R.
2012-01-01
This commentary advocates the use of mixed methods research--that is the integration of qualitative and quantitative methods in a single study--in applied linguistics. Based on preliminary findings from a research project in progress, some reflections on the current practice of mixing methods as a new trend in applied linguistics are put forward.…
NASA Astrophysics Data System (ADS)
Riba, Jordi-Roger
2015-09-01
This paper analyzes the skin and proximity effects in different conductive nonmagnetic straight conductor configurations subjected to applied alternating currents and voltages. These effects have important consequences, including a rise of the ac resistance, which in turn increases power loss, thus limiting the rating for the conductor. Alternating current (ac) resistance is important in power conductors and bus bars for line frequency applications, as well as in smaller conductors for high frequency applications. Despite the importance of this topic, it is not usually analyzed in detail in undergraduate and even in graduate studies. To address this, this paper compares the results provided by available exact formulas for simple geometries with those obtained by means of two-dimensional finite element method (FEM) simulations and experimental results. The paper also shows that FEM results are very accurate and more general than those provided by the formulas, since FEM models can be applied in a wide range of electrical frequencies and configurations.
NASA Astrophysics Data System (ADS)
Bradley, A. M.
2013-12-01
My poster will describe dc3dm, a free open source software (FOSS) package that efficiently forms and applies the linear operator relating slip and traction components on a nonuniformly discretized rectangular planar fault in a homogeneous elastic (HE) half space. This linear operator implements what is called the displacement discontinuity method (DDM). The key properties of dc3dm are: 1. The mesh can be nonuniform. 2. Work and memory scale roughly linearly in the number of elements (rather than quadratically). 3. The order of accuracy of my method on a nonuniform mesh is the same as that of the standard method on a uniform mesh. Property 2 is achieved using my FOSS package hmmvp [AGU 2012]. A nonuniform mesh (property 1) is natural for some problems. For example, in a rate-state friction simulation, nucleation length, and so required element size, scales reciprocally with effective normal stress. Property 3 assures that if a nonuniform mesh is more efficient than a uniform mesh (in the sense of accuracy per element) at one level of mesh refinement, it will remain so at all further mesh refinements. I use the routine DC3D of Y. Okada, which calculates the stress tensor at a receiver resulting from a rectangular uniform dislocation source in an HE half space. On a uniform mesh, straightforward application of this Green's function (GF) yields a DDM I refer to as DDMu. On a nonuniform mesh, this same procedure leads to artifacts that degrade the order of accuracy of the DDM. I have developed a method I call IGA that implements the DDM using this GF for a nonuniformly discretized mesh having certain properties. Importantly, IGA's order of accuracy on a nonuniform mesh is the same as DDMu's on a uniform one. Boundary conditions can be periodic in the surface-parallel direction (in both directions if the GF is for a whole space), velocity on any side, and free surface. The mesh must have the following main property: each uniquely sized element must tile each element
PLURAL METALLIC COATINGS ON URANIUM AND METHOD OF APPLYING SAME
Gray, A.G.
1958-09-16
A method is described of applying protective coatings to uranlum articles. It consists in applying chromium plating to such uranium articles by electrolysis in a chromic acid bath and subsequently applying, to this minum containing alloy. This aluminum contalning alloy (for example one of aluminum and silicon) may then be used as a bonding alloy between the chromized surface and an aluminum can.
Control method for peak power delivery with limited DC-bus voltage
Edwards, John; Xu, Longya; Bhargava, Brij B.
2006-09-05
A method for driving a neutral point-clamped multi-level voltage source inverter supplying a synchronous motor is provided. A DC current is received at a neutral point-clamped multi-level voltage source inverter. The inverter has first, second, and third output nodes. The inverter also has a plurality of switches. A desired speed of a synchronous motor connected to the inverter by the first second and third nodes is received by the inverter. The synchronous motor has a rotor and the speed of the motor is defined by the rotational rate of the rotor. A position of the rotor is sensed, current flowing to the motor out of at least two of the first, second, and third output nodes is sensed, and predetermined switches are automatically activated by the inverter responsive to the sensed rotor position, the sensed current, and the desired speed.
Moukalled, F.; Aziz, A. Abdel; Darwish, M.
2009-09-09
This paper reports on the performance of a high resolution implemented as part of an implicit fully coupled velocity-pressure algorithm for the solution of laminar incompressible flow problems. The numerical implementation of high resolution convective schemes follows two techniques; (i) the Deferred Correction (DC) approach, and (ii) the Normalized Weighting Factor (NWF) method. The superiority of the NWF method over the DC approach is demonstrated by solving the sudden expansion in a square cavity problem. Results indicate that the number of iterations needed by the NWF solver is grid independent. Moreover, recorded CPU time values reveal that the NWF method substantially reduces the computational cost.
DC voltage-voltage method to measure the interface traps in sub-micron MOSTs
NASA Astrophysics Data System (ADS)
Jie, B. B.; Li, M. F.; Chim, W. K.; Chan, D. S. H.; Lo, K. F.
1999-07-01
A dc voltage-voltage technique for the measurement of stress-generated interface traps in submicron MOSTs is demonstrated. This method uses the source-bulk-drain of a submicron MOST as an effective lateral bipolar transistor when the channel region is out of inversion under the control of the gate voltage Vgb. The emitter injects the minority carriers to the base region and the collector is open. The Vcb versus Vgb spectrum can be explained quantitatively in the spirit of the extended Ebers-Moll equations and interface trap SRH recombination. The spectrum shows clear information on stress-generated interface traps located at the collector-junction region. The new method has the advantages of simplicity, high sensitivity and wide application range to different device structures. A single effective interface trap at the source or drain side could be detected, and interface traps at the source side can be separated from those at the drain side by the new method. Moreover, we propose an improved gated-diode method to separate interface traps at the source side from those at the drain side.
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.
Building "Applied Linguistic Historiography": Rationale, Scope, and Methods
ERIC Educational Resources Information Center
Smith, Richard
2016-01-01
In this article I argue for the establishment of "Applied Linguistic Historiography" (ALH), that is, a new domain of enquiry within applied linguistics involving a rigorous, scholarly, and self-reflexive approach to historical research. Considering issues of rationale, scope, and methods in turn, I provide reasons why ALH is needed and…
Applying Mixed Methods Research at the Synthesis Level: An Overview
ERIC Educational Resources Information Center
Heyvaert, Mieke; Maes, Bea; Onghena, Patrick
2011-01-01
Historically, qualitative and quantitative approaches have been applied relatively separately in synthesizing qualitative and quantitative evidence, respectively, in several research domains. However, mixed methods approaches are becoming increasingly popular nowadays, and practices of combining qualitative and quantitative research components at…
Zolper, John C.; Sherwin, Marc E.; Baca, Albert G.
2000-01-01
A method for making compound semiconductor devices including the use of a p-type dopant is disclosed wherein the dopant is co-implanted with an n-type donor species at the time the n-channel is formed and a single anneal at moderate temperature is then performed. Also disclosed are devices manufactured using the method. In the preferred embodiment n-MESFETs and other similar field effect transistor devices are manufactured using C ions co-implanted with Si atoms in GaAs to form an n-channel. C exhibits a unique characteristic in the context of the invention in that it exhibits a low activation efficiency (typically, 50% or less) as a p-type dopant, and consequently, it acts to sharpen the Si n-channel by compensating Si donors in the region of the Si-channel tail, but does not contribute substantially to the acceptor concentration in the buried p region. As a result, the invention provides for improved field effect semiconductor and related devices with enhancement of both DC and high-frequency performance.
ERIC Educational Resources Information Center
Ates, Salih
2005-01-01
This study was undertaken to explore the effectiveness of the learning-cycle method when teaching direct current (DC) circuits to university students. Four Physics II classes participated in the study, which lasted approximately two and a half weeks in the middle of the spring semester of 2003. Participants were 120 freshmen (55 females and 65…
Optical methods of stress analysis applied to cracked components
NASA Technical Reports Server (NTRS)
Smith, C. W.
1991-01-01
After briefly describing the principles of frozen stress photoelastic and moire interferometric analyses, and the corresponding algorithms for converting optical data from each method into stress intensity factors (SIF), the methods are applied to the determination of crack shapes, SIF determination, crack closure displacement fields, and pre-crack damage mechanisms in typical aircraft component configurations.
Applied AC and DC magnetic fields cause alterations in the mitotic cycle of early sea urchin embryos
Levin, M.; Ernst, S.G.
1995-09-01
This study demonstrates that exposure to 60 Hz magnetic fields (3.4--8.8 mt) and magnetic fields over the range DC-600 kHz (2.5--6.5 mT) can alter the early embryonic development of sea urchin embryos by inducing alterations in the timing of the cell cycle. Batches of fertilized eggs were exposed to the fields produced by a coil system. Samples of the continuous cultures were taken and scored for cell division. The times of both the first and second cell divisions were advanced by ELF AC fields and by static fields. The magnitude of the 60 Hz effect appears proportional to the field strength over the range tested. the relationship to field frequency was nonlinear and complex. For certain frequencies above the ELF range, the exposure resulted in a delay of the onset of mitosis. The advance of mitosis was also dependent on the duration of exposure and on the timing of exposure relative to fertilization.
Fokker-Planck equation with arbitrary dc and ac fields: continued fraction method.
Lee, Chee Kong; Gong, Jiangbin
2011-07-01
The continued fraction method (CFM) is used to solve the Fokker-Planck equation with arbitrary dc and ac fields. With an appropriate choice of basis functions, the Fokker-Planck equation is converted into a set of linear algebraic equations with short-ranged coupling and then CFM is implemented to obtain numerical solutions with high efficiency. Both a proposed perturbative CFM and the numerically exact matrix CFM are used to study the nonlinear response of driven systems, with their results compared to assess the validity regime of the perturbative approach. The proposed perturbative CFM approach needs scalar quantities only and hence is more efficient within its validity regime. Two nonlinear systems of different nature are used as examples: molecular dipole (rotational Brownian motion) and particle in a periodic potential (translational Brownian motion). The associated full dynamics is presented in the compact form of hysteresis loops. It is observed that as the strength of an AC driving field increases, pronounced nonlinear effects are manifested in the deformation of the hysteresis loops. PMID:21867110
Lawler, J.S.
2001-10-29
The brushless dc motor (BDCM) has high-power density and efficiency relative to other motor types. These properties make the BDCM well suited for applications in electric vehicles provided a method can be developed for driving the motor over the 4 to 6:1 constant power speed range (CPSR) required by such applications. The present state of the art for constant power operation of the BDCM is conventional phase advance (CPA) [1]. In this paper, we identify key limitations of CPA. It is shown that the CPA has effective control over the developed power but that the current magnitude is relatively insensitive to power output and is inversely proportional to motor inductance. If the motor inductance is low, then the rms current at rated power and high speed may be several times larger than the current rating. The inductance required to maintain rms current within rating is derived analytically and is found to be large relative to that of BDCM designs using high-strength rare earth magnets. Th us, the CPA requires a BDCM with a large equivalent inductance.
Design and development of DC high current sensor using Hall-Effect method
NASA Astrophysics Data System (ADS)
Dewi, Sasti Dwi Tungga; Panatarani, C.; Joni, I. Made
2016-02-01
This paper report a newly developed high DC current sensor by using a Hall effect method and also the measurement system. The Hall effect sensor receive the magnetic field generated by a current carrying conductor wire. The SS49E (Honeywell) magnetoresistive sensor was employed to sense the magnetic field from the field concentrator. The voltage received from SS49E then converted into digital by using analog to digital converter (ADC-10 bit). The digital data then processed in the microcontroller to be displayed as the value of the electric current in the LCD display. In addition the measurement was interfaced into Personal Computer (PC) using the communication protocols of RS232 which was finally displayed in real-time graphical form on the PC display. The performance test on the range ± 40 Ampere showed that the maximum relative error is 5.26%. It is concluded that the sensors and the measurement system worked properly according to the design with acceptable accuracy.
Aircraft operability methods applied to space launch vehicles
Young, D.
1997-01-01
The commercial space launch market requirement for low vehicle operations costs necessitates the application of methods and technologies developed and proven for complex aircraft systems. The {open_quotes}building in{close_quotes} of reliability and maintainability, which is applied extensively in the aircraft industry, has yet to be applied to the maximum extent possible on launch vehicles. Use of vehicle system and structural health monitoring, automated ground systems and diagnostic design methods derived from aircraft applications support the goal of achieving low cost launch vehicle operations. Transforming these operability techniques to space applications where diagnostic effectiveness has significantly different metrics is critical to the success of future launch systems. These concepts will be discussed with reference to broad launch vehicle applicability. Lessons learned and techniques used in the adaptation of these methods will be outlined drawing from recent aircraft programs and implementation on phase 1 of the X-33/RLV technology development program. {copyright} {ital 1997 American Institute of Physics.}
Aircraft operability methods applied to space launch vehicles
NASA Astrophysics Data System (ADS)
Young, Douglas
1997-01-01
The commercial space launch market requirement for low vehicle operations costs necessitates the application of methods and technologies developed and proven for complex aircraft systems. The ``building in'' of reliability and maintainability, which is applied extensively in the aircraft industry, has yet to be applied to the maximum extent possible on launch vehicles. Use of vehicle system and structural health monitoring, automated ground systems and diagnostic design methods derived from aircraft applications support the goal of achieving low cost launch vehicle operations. Transforming these operability techniques to space applications where diagnostic effectiveness has significantly different metrics is critical to the success of future launch systems. These concepts will be discussed with reference to broad launch vehicle applicability. Lessons learned and techniques used in the adaptation of these methods will be outlined drawing from recent aircraft programs and implementation on phase 1 of the X-33/RLV technology development program.
Probabilistic Methods for Uncertainty Propagation Applied to Aircraft Design
NASA Technical Reports Server (NTRS)
Green, Lawrence L.; Lin, Hong-Zong; Khalessi, Mohammad R.
2002-01-01
Three methods of probabilistic uncertainty propagation and quantification (the method of moments, Monte Carlo simulation, and a nongradient simulation search method) are applied to an aircraft analysis and conceptual design program to demonstrate design under uncertainty. The chosen example problems appear to have discontinuous design spaces and thus these examples pose difficulties for many popular methods of uncertainty propagation and quantification. However, specific implementation features of the first and third methods chosen for use in this study enable successful propagation of small uncertainties through the program. Input uncertainties in two configuration design variables are considered. Uncertainties in aircraft weight are computed. The effects of specifying required levels of constraint satisfaction with specified levels of input uncertainty are also demonstrated. The results show, as expected, that the designs under uncertainty are typically heavier and more conservative than those in which no input uncertainties exist.
Applying Taguchi Methods To Brazing Of Rocket-Nozzle Tubes
NASA Technical Reports Server (NTRS)
Gilbert, Jeffrey L.; Bellows, William J.; Deily, David C.; Brennan, Alex; Somerville, John G.
1995-01-01
Report describes experimental study in which Taguchi Methods applied with view toward improving brazing of coolant tubes in nozzle of main engine of space shuttle. Dr. Taguchi's parameter design technique used to define proposed modifications of brazing process reducing manufacturing time and cost by reducing number of furnace brazing cycles and number of tube-gap inspections needed to achieve desired small gaps between tubes.
Alternating method applied to edge and surface crack problems.
NASA Technical Reports Server (NTRS)
Hartranft, R. J.; Sih, G. C.
1973-01-01
The alternating method, which intimately combines analytical results with numerical calculations, as applied to edge crack problems in two dimensions and surface crack problems in three dimensions, is treated. The case of a crack perpendicular to the edge of a semiinfinite material is considered. One of the crack geometries that has received continual interest in fracture mechanics is that of a semielliptical crack whose major axis lies on a stress free surface. In order to demonstrate the sensitivity of the solution to the influence of the free surface the semicircular crack problem is again treated by the alternating method.
Newton-Krylov methods applied to nonequilibrium radiation diffusion
Knoll, D.A.; Rider, W.J.; Olsen, G.L.
1998-03-10
The authors present results of applying a matrix-free Newton-Krylov method to a nonequilibrium radiation diffusion problem. Here, there is no use of operator splitting, and Newton`s method is used to convert the nonlinearities within a time step. Since the nonlinear residual is formed, it is used to monitor convergence. It is demonstrated that a simple Picard-based linearization produces a sufficient preconditioning matrix for the Krylov method, thus elevating the need to form or store a Jacobian matrix for Newton`s method. They discuss the possibility that the Newton-Krylov approach may allow larger time steps, without loss of accuracy, as compared to an operator split approach where nonlinearities are not converged within a time step.
NASA Astrophysics Data System (ADS)
Kohara, Yusuke; Kubo, Naoya; Nishiyama, Tomofumi; Koizuka, Taiki; Alimudin, Mohammad; Rahmat, Amirul; Okamura, Hitoshi; Yamanokuchi, Tomoyuki; Nakamura, Kazuyuki
2016-04-01
Two new parallel bus coding methods for generating a DC-balanced code with additional bits are proposed to achieve the self-stabilization of the intermediate power level in Stacked-Vdd integrated circuits. They contribute to producing a uniform switching current in parallel inputs and outputs (I/Os). Type I coding minimizes the difference in the number of switchings between the upper and lower CMOS I/Os by 8B/10B coding followed by toggle conversion. Type II coding, in which the multi-value running disparity control feature is integrated into the bus-invert coding, requires only one redundant bit for any wider bus. Their DC-balanced feature and the stability effect of the intermediate power level in the Stacked-Vdd structure were experimentally confirmed from the measurement results obtained from the developed test chips.
Minami, Tadatsugu; Ohtani, Yuusuke; Miyata, Toshihiro; Kuboi, Takeshi
2007-07-15
A newly developed Al-doped ZnO (AZO) thin-film magnetron-sputtering deposition technique that decreases resistivity, improves resistivity distribution, and produces high-rate depositions has been demonstrated by dc magnetron-sputtering depositions that incorporate rf power (dc+rf-MS), either with or without the introduction of H{sub 2} gas into the deposition chamber. The dc+rf-MS preparations were carried out in a pure Ar or an Ar+H{sub 2} (0%-2%) gas atmosphere at a pressure of 0.4 Pa by adding a rf component (13.56 MHz) to a constant dc power of 80 W. The deposition rate in a dc+rf-MS deposition incorporating a rf power of 150 W was approximately 62 nm/min, an increase from the approximately 35 nm/min observed in dc magnetron sputtering with a dc power of 80 W. A resistivity as low as 3x10{sup -4} {omega} cm and an improved resistivity distribution could be obtained in AZO thin films deposited on substrates at a low temperature of 150 deg. C by dc+rf-MS with the introduction of hydrogen gas with a content of 1.5%. This article describes the effects of adding a rf power component (i.e., dc+rf-MS deposition) as well as introducing H{sub 2} gas into dc magnetron-sputtering preparations of transparent conducting AZO thin films.
Applying Quantitative Genetic Methods to Primate Social Behavior
Brent, Lauren J. N.
2013-01-01
Increasingly, behavioral ecologists have applied quantitative genetic methods to investigate the evolution of behaviors in wild animal populations. The promise of quantitative genetics in unmanaged populations opens the door for simultaneous analysis of inheritance, phenotypic plasticity, and patterns of selection on behavioral phenotypes all within the same study. In this article, we describe how quantitative genetic techniques provide studies of the evolution of behavior with information that is unique and valuable. We outline technical obstacles for applying quantitative genetic techniques that are of particular relevance to studies of behavior in primates, especially those living in noncaptive populations, e.g., the need for pedigree information, non-Gaussian phenotypes, and demonstrate how many of these barriers are now surmountable. We illustrate this by applying recent quantitative genetic methods to spatial proximity data, a simple and widely collected primate social behavior, from adult rhesus macaques on Cayo Santiago. Our analysis shows that proximity measures are consistent across repeated measurements on individuals (repeatable) and that kin have similar mean measurements (heritable). Quantitative genetics may hold lessons of considerable importance for studies of primate behavior, even those without a specific genetic focus. PMID:24659839
Methods for model selection in applied science and engineering.
Field, Richard V., Jr.
2004-10-01
Mathematical models are developed and used to study the properties of complex systems and/or modify these systems to satisfy some performance requirements in just about every area of applied science and engineering. A particular reason for developing a model, e.g., performance assessment or design, is referred to as the model use. Our objective is the development of a methodology for selecting a model that is sufficiently accurate for an intended use. Information on the system being modeled is, in general, incomplete, so that there may be two or more models consistent with the available information. The collection of these models is called the class of candidate models. Methods are developed for selecting the optimal member from a class of candidate models for the system. The optimal model depends on the available information, the selected class of candidate models, and the model use. Classical methods for model selection, including the method of maximum likelihood and Bayesian methods, as well as a method employing a decision-theoretic approach, are formulated to select the optimal model for numerous applications. There is no requirement that the candidate models be random. Classical methods for model selection ignore model use and require data to be available. Examples are used to show that these methods can be unreliable when data is limited. The decision-theoretic approach to model selection does not have these limitations, and model use is included through an appropriate utility function. This is especially important when modeling high risk systems, where the consequences of using an inappropriate model for the system can be disastrous. The decision-theoretic method for model selection is developed and applied for a series of complex and diverse applications. These include the selection of the: (1) optimal order of the polynomial chaos approximation for non-Gaussian random variables and stationary stochastic processes, (2) optimal pressure load model to be
Applied methods of testing and evaluation for IR imaging system
NASA Astrophysics Data System (ADS)
Liao, Xiao-yue; Lu, Jin
2009-07-01
Different methods of testing and evaluation for IR imaging system are used with the application of the 2nd and the 3rd generation infrared detectors. The performance of IR imaging system can be reflected by many specifications, such as Noise Equivalent Temperature Difference (NETD), Nonuniformity, system Modulation Transfer Function (MTF), Minimum Resolvable Temperature Difference (MRTD), and Minimum Detectable Temperature Difference (MRTD) etc. The sensitivity of IR sensors is estimated by NETD. The sensitivity of thermal imaging sensors and space resolution are evaluated by MRTD, which is the chief specification of system. In this paper, the theoretical analysis of different testing methods is introduced. The characteristics of them are analyzed and compared. Based on discussing the factors that affect measurement results, an applied method of testing NETD and MRTD for IR system is proposed.
The Lattice Boltzmann Method applied to neutron transport
Erasmus, B.; Van Heerden, F. A.
2013-07-01
In this paper the applicability of the Lattice Boltzmann Method to neutron transport is investigated. One of the main features of the Lattice Boltzmann method is the simultaneous discretization of the phase space of the problem, whereby particles are restricted to move on a lattice. An iterative solution of the operator form of the neutron transport equation is presented here, with the first collision source as the starting point of the iteration scheme. A full description of the discretization scheme is given, along with the quadrature set used for the angular discretization. An angular refinement scheme is introduced to increase the angular coverage of the problem phase space and to mitigate lattice ray effects. The method is applied to a model problem to investigate its applicability to neutron transport and the results are compared to a reference solution calculated, using MCNP. (authors)
Kang, Kwan Hyoung; Li, Dongqing
2005-06-15
There is a concentration-polarization (CP) force acting on a particle submerged in an electrolyte solution with a concentration (conductivity) gradient under an externally applied DC electric field. This force originates from the two mechanisms: (i) gradient of electrohydrodynamic pressure around the particle developed by the Coulombic force acting on induced free charges by the concentration polarization, and (ii) dielectric force due to nonuniform electric field induced by the conductivity gradient. A perturbation analysis is performed for the electric field, the concentration field, and the hydrodynamic field, under the assumptions of creeping flow and small concentration gradient. The leading order component of this force acting on a dielectric spherical particle is obtained by integrating the Maxwell and the hydrodynamic stress tensors. The analytical results are validated by comparing the surface pressure and the skin friction to those of a numerical analysis. The CP force is proportional to square of the applied electric field, effective for electrically neutral particles, and always directs towards the region of higher ionic concentration. The magnitude of the CP force is compared to that of the electrophoretic and the conventional dielectrophoretic forces. PMID:15897097
Advancing MODFLOW Applying the Derived Vector Space Method
NASA Astrophysics Data System (ADS)
Herrera, G. S.; Herrera, I.; Lemus-García, M.; Hernandez-Garcia, G. D.
2015-12-01
The most effective domain decomposition methods (DDM) are non-overlapping DDMs. Recently a new approach, the DVS-framework, based on an innovative discretization method that uses a non-overlapping system of nodes (the derived-nodes), was introduced and developed by I. Herrera et al. [1, 2]. Using the DVS-approach a group of four algorithms, referred to as the 'DVS-algorithms', which fulfill the DDM-paradigm (i.e. the solution of global problems is obtained by resolution of local problems exclusively) has been derived. Such procedures are applicable to any boundary-value problem, or system of such equations, for which a standard discretization method is available and then software with a high degree of parallelization can be constructed. In a parallel talk, in this AGU Fall Meeting, Ismael Herrera will introduce the general DVS methodology. The application of the DVS-algorithms has been demonstrated in the solution of several boundary values problems of interest in Geophysics. Numerical examples for a single-equation, for the cases of symmetric, non-symmetric and indefinite problems were demonstrated before [1,2]. For these problems DVS-algorithms exhibited significantly improved numerical performance with respect to standard versions of DDM algorithms. In view of these results our research group is in the process of applying the DVS method to a widely used simulator for the first time, here we present the advances of the application of this method for the parallelization of MODFLOW. Efficiency results for a group of tests will be presented. References [1] I. Herrera, L.M. de la Cruz and A. Rosas-Medina. Non overlapping discretization methods for partial differential equations, Numer Meth Part D E, (2013). [2] Herrera, I., & Contreras Iván "An Innovative Tool for Effectively Applying Highly Parallelized Software To Problems of Elasticity". Geofísica Internacional, 2015 (In press)
About the method of investigation of applied unstable process
NASA Astrophysics Data System (ADS)
Romanova, O. V.; Sapega, V. F.
2003-04-01
ABOUT THE METHOD OF INVESTIGATION OF APPLIED UNSTABLE PROCESS O.V. Romanova (1), V.F. Sapega (1) (1) All-russian geological institute (VSEGEI) zapgeo@mail.wpus.net (mark: for Romanova)/Fax: +7-812-3289283 Samples of Late Proterosoic (Rephean) rocks from Arkhangelsk, Jaroslav and Leningrad regions were prepared by the developed method of sample preparation and researched by X-ray analysis. The presence of mantle fluid process had been previously estabished in some of the samples (injecting tuffizites) (Kazak, Jakobsson, 1999). It appears that unchanged rephean rocks contain the set of low-temperature minerals as illite, chlorite, vermiculite, goethite, indicates conditions of diagenesis with temperature less than 300° C. Presense of corrensite, rectorite, illite-montmorillonite indicates application of the post-diagenesis low-temperature process to the original sediment rock. At the same time the rocks involved in the fluid process, contain such minerals as olivine, pyrope, graphite and indicate application of the high-temperature process not less than 650-800°C. Within these samples a set of low-temperature minerals occur also, this demonstrates the short-timing and disequilibrium of the applied high-temperature process. Therefore implementation of the x-ray method provides unambiguous criterion to the establishment of the fluid process which as a rule is coupled with the development of kimberlite rock fields.
Modeling of DC spacecraft power systems
NASA Technical Reports Server (NTRS)
Berry, F. C.
1995-01-01
Future spacecraft power systems must be capable of supplying power to various loads. This delivery of power may necessitate the use of high-voltage, high-power dc distribution systems to transmit power from the source to the loads. Using state-of-the-art power conditioning electronics such as dc-dc converters, complex series and parallel configurations may be required at the interface between the source and the distribution system and between the loads and the distribution system. This research will use state-variables to model and simulate a dc spacecraft power system. Each component of the dc power system will be treated as a multiport network, and a state model will be written with the port voltages as the inputs. The state model of a component will be solved independently from the other components using its state transition matrix. A state-space averaging method is developed first in general for any dc-dc switching converter, and then demonstrated in detail for the particular case of the boost power stage. General equations for both steady-state (dc) and dynamic effects (ac) are obtained, from which important transfer functions are derived and applied to a special case of the boost power stage.
"Influence Method" applied to measure a moderated neutron flux
NASA Astrophysics Data System (ADS)
Rios, I. J.; Mayer, R. E.
2016-01-01
The "Influence Method" is conceived for the absolute determination of a nuclear particle flux in the absence of known detector efficiency. This method exploits the influence of the presence of one detector, in the count rate of another detector when they are placed one behind the other and define statistical estimators for the absolute number of incident particles and for the efficiency. The method and its detailed mathematical description were recently published (Rios and Mayer, 2015 [1]). In this article we apply it to the measurement of the moderated neutron flux produced by an 241AmBe neutron source surrounded by a light water sphere, employing a pair of 3He detectors. For this purpose, the method is extended for its application where particles arriving at the detector obey a Poisson distribution and also, for the case when efficiency is not constant over the energy spectrum of interest. Experimental distributions and derived parameters are compared with theoretical predictions of the method and implications concerning the potential application to the absolute calibration of neutron sources are considered.
Extrapolation techniques applied to matrix methods in neutron diffusion problems
NASA Technical Reports Server (NTRS)
Mccready, Robert R
1956-01-01
A general matrix method is developed for the solution of characteristic-value problems of the type arising in many physical applications. The scheme employed is essentially that of Gauss and Seidel with appropriate modifications needed to make it applicable to characteristic-value problems. An iterative procedure produces a sequence of estimates to the answer; and extrapolation techniques, based upon previous behavior of iterants, are utilized in speeding convergence. Theoretically sound limits are placed on the magnitude of the extrapolation that may be tolerated. This matrix method is applied to the problem of finding criticality and neutron fluxes in a nuclear reactor with control rods. The two-dimensional finite-difference approximation to the two-group neutron fluxes in a nuclear reactor with control rods. The two-dimensional finite-difference approximation to the two-group neutron-diffusion equations is treated. Results for this example are indicated.
Adapted G-mode Clustering Method applied to Asteroid Taxonomy
NASA Astrophysics Data System (ADS)
Hasselmann, Pedro H.; Carvano, Jorge M.; Lazzaro, D.
2013-11-01
The original G-mode was a clustering method developed by A. I. Gavrishin in the late 60's for geochemical classification of rocks, but was also applied to asteroid photometry, cosmic rays, lunar sample and planetary science spectroscopy data. In this work, we used an adapted version to classify the asteroid photometry from SDSS Moving Objects Catalog. The method works by identifying normal distributions in a multidimensional space of variables. The identification starts by locating a set of points with smallest mutual distance in the sample, which is a problem when data is not planar. Here we present a modified version of the G-mode algorithm, which was previously written in FORTRAN 77, in Python 2.7 and using NumPy, SciPy and Matplotlib packages. The NumPy was used for array and matrix manipulation and Matplotlib for plot control. The Scipy had a import role in speeding up G-mode, Scipy.spatial.distance.mahalanobis was chosen as distance estimator and Numpy.histogramdd was applied to find the initial seeds from which clusters are going to evolve. Scipy was also used to quickly produce dendrograms showing the distances among clusters. Finally, results for Asteroids Taxonomy and tests for different sample sizes and implementations are presented.
NASA Astrophysics Data System (ADS)
Vasilchenko, V. E.; Kharintsev, S. S.; Salakhov, M. Kh
2013-12-01
This paper presents a modified dc-pulsed low voltage electrochemical method in which a duty cycle is self tuned while etching. A higher yield of gold tips suitable for performing tip-enhanced Raman scattering (TERS) measurements is demonstrated. The improvement is caused by the self-control of the etching rate along the full surface of the tip. A capability of the gold tips to enhance a Raman signal is exemplified by TERS spectroscopy of single walled carbon nanotubes bundle, sulfur and vanadium oxide.
Yang, Ping; Nai, Chang-Xin; Dong, Lu; Wang, Qi; Wang, Yan-Wen
2006-01-01
Two types of double high density polyethylene (HDPE) liners landfill that clay or geogrid was added between the two HDPE liners. The general resistance of the second mode is 15% larger than the general resistance of the first mode in the primary HDPE liner detection, and 20% larger than that of the first one in the secondary HDPE liner detection. High voltage DC method can accomplish the leakage detection and location of these two types of landfill and the error of leakage location is less than 10cm when electrode space is 1m. PMID:16599145
The Exoplanet Census: A General Method Applied to Kepler
NASA Astrophysics Data System (ADS)
Youdin, Andrew N.
2011-11-01
We develop a general method to fit the underlying planetary distribution function (PLDF) to exoplanet survey data. This maximum likelihood method accommodates more than one planet per star and any number of planet or target star properties. We apply the method to announced Kepler planet candidates that transit solar-type stars. The Kepler team's estimates of the detection efficiency are used and are shown to agree with theoretical predictions for an ideal transit survey. The PLDF is fit to a joint power law in planet radius, down to 0.5 R ⊕, and orbital period, up to 50 days. The estimated number of planets per star in this sample is ~0.7-1.4, where the range covers systematic uncertainties in the detection efficiency. To analyze trends in the PLDF we consider four planet samples, divided between shorter and longer periods at 7 days and between large and small radii at 3 R ⊕. The size distribution changes appreciably between these four samples, revealing a relative deficit of ~3 R ⊕ planets at the shortest periods. This deficit is suggestive of preferential evaporation and sublimation of Neptune- and Saturn-like planets. If the trend and explanation hold, it would be spectacular observational support of the core accretion and migration hypotheses, and would allow refinement of these theories.
Analytical methods applied to diverse types of Brazilian propolis
2011-01-01
Propolis is a bee product, composed mainly of plant resins and beeswax, therefore its chemical composition varies due to the geographic and plant origins of these resins, as well as the species of bee. Brazil is an important supplier of propolis on the world market and, although green colored propolis from the southeast is the most known and studied, several other types of propolis from Apis mellifera and native stingless bees (also called cerumen) can be found. Propolis is usually consumed as an extract, so the type of solvent and extractive procedures employed further affect its composition. Methods used for the extraction; analysis the percentage of resins, wax and insoluble material in crude propolis; determination of phenolic, flavonoid, amino acid and heavy metal contents are reviewed herein. Different chromatographic methods applied to the separation, identification and quantification of Brazilian propolis components and their relative strengths are discussed; as well as direct insertion mass spectrometry fingerprinting. Propolis has been used as a popular remedy for several centuries for a wide array of ailments. Its antimicrobial properties, present in propolis from different origins, have been extensively studied. But, more recently, anti-parasitic, anti-viral/immune stimulating, healing, anti-tumor, anti-inflammatory, antioxidant and analgesic activities of diverse types of Brazilian propolis have been evaluated. The most common methods employed and overviews of their relative results are presented. PMID:21631940
Understanding the impulse response method applied to concrete bridge decks
NASA Astrophysics Data System (ADS)
Clem, D. J.; Popovics, J. S.; Schumacher, T.; Oh, T.; Ham, S.; Wu, D.
2013-01-01
The Impulse Response (IR) method is a well-established form of non-destructive testing (NDT) where the dynamic response of an element resulting from an impact event (hammer blow) is measured with a geophone to make conclusions about the element's integrity, stiffness, and/or support conditions. The existing ASTM Standard C1740-10 prescribes a set of parameters that can be used to evaluate the conditions above. These parameters are computed from the so-called `mobility' spectrum which is obtained by dividing the measured bridge deck response by the measured impact force in the frequency domain. While applying the test method in the laboratory as well as on an actual in-service concrete bridge deck, the authors of this paper observed several limitations that are presented and discussed in this paper. In order to better understand the underlying physics of the IR method, a Finite Element (FE) model was created. Parameters prescribed in the Standard were then computed from the FE data and are discussed. One main limitation appears to be the use of a fixed upper frequency of 800 Hz. Test data from the real bridge deck as well as the FE model both show that most energy is found above that limit. This paper presents and discusses limitations of the ASTM Standard found by the authors and suggests ways for improving it.
THE EXOPLANET CENSUS: A GENERAL METHOD APPLIED TO KEPLER
Youdin, Andrew N.
2011-11-20
We develop a general method to fit the underlying planetary distribution function (PLDF) to exoplanet survey data. This maximum likelihood method accommodates more than one planet per star and any number of planet or target star properties. We apply the method to announced Kepler planet candidates that transit solar-type stars. The Kepler team's estimates of the detection efficiency are used and are shown to agree with theoretical predictions for an ideal transit survey. The PLDF is fit to a joint power law in planet radius, down to 0.5 R{sub Circled-Plus }, and orbital period, up to 50 days. The estimated number of planets per star in this sample is {approx}0.7-1.4, where the range covers systematic uncertainties in the detection efficiency. To analyze trends in the PLDF we consider four planet samples, divided between shorter and longer periods at 7 days and between large and small radii at 3 R{sub Circled-Plus }. The size distribution changes appreciably between these four samples, revealing a relative deficit of {approx}3 R{sub Circled-Plus} planets at the shortest periods. This deficit is suggestive of preferential evaporation and sublimation of Neptune- and Saturn-like planets. If the trend and explanation hold, it would be spectacular observational support of the core accretion and migration hypotheses, and would allow refinement of these theories.
Six Sigma methods applied to cryogenic coolers assembly line
NASA Astrophysics Data System (ADS)
Ventre, Jean-Marc; Germain-Lacour, Michel; Martin, Jean-Yves; Cauquil, Jean-Marc; Benschop, Tonny; Griot, René
2009-05-01
Six Sigma method have been applied to manufacturing process of a rotary Stirling cooler: RM2. Name of the project is NoVa as main goal of the Six Sigma approach is to reduce variability (No Variability). Project has been based on the DMAIC guideline following five stages: Define, Measure, Analyse, Improve, Control. Objective has been set on the rate of coolers succeeding performance at first attempt with a goal value of 95%. A team has been gathered involving people and skills acting on the RM2 manufacturing line. Measurement System Analysis (MSA) has been applied to test bench and results after R&R gage show that measurement is one of the root cause for variability in RM2 process. Two more root causes have been identified by the team after process mapping analysis: regenerator filling factor and cleaning procedure. Causes for measurement variability have been identified and eradicated as shown by new results from R&R gage. Experimental results show that regenerator filling factor impacts process variability and affects yield. Improved process haven been set after new calibration process for test bench, new filling procedure for regenerator and an additional cleaning stage have been implemented. The objective for 95% coolers succeeding performance test at first attempt has been reached and kept for a significant period. RM2 manufacturing process is now managed according to Statistical Process Control based on control charts. Improvement in process capability have enabled introduction of sample testing procedure before delivery.
New method of applying conformal group to quantum fields
NASA Astrophysics Data System (ADS)
Han, Lei; Wang, Hai-Jun
2015-09-01
Most of previous work on applying the conformal group to quantum fields has emphasized its invariant aspects, whereas in this paper we find that the conformal group can give us running quantum fields, with some constants, vertex and Green functions running, compatible with the scaling properties of renormalization group method (RGM). We start with the renormalization group equation (RGE), in which the differential operator happens to be a generator of the conformal group, named dilatation operator. In addition we link the operator/spatial representation and unitary/spinor representation of the conformal group by inquiring a conformal-invariant interaction vertex mimicking the similar process of Lorentz transformation applied to Dirac equation. By this kind of application, we find out that quite a few interaction vertices are separately invariant under certain transformations (generators) of the conformal group. The significance of these transformations and vertices is explained. Using a particular generator of the conformal group, we suggest a new equation analogous to RGE which may lead a system to evolve from asymptotic regime to nonperturbative regime, in contrast to the effect of the conventional RGE from nonperturbative regime to asymptotic regime. Supported by NSFC (91227114)
Teaching organization theory for healthcare management: three applied learning methods.
Olden, Peter C
2006-01-01
Organization theory (OT) provides a way of seeing, describing, analyzing, understanding, and improving organizations based on patterns of organizational design and behavior (Daft 2004). It gives managers models, principles, and methods with which to diagnose and fix organization structure, design, and process problems. Health care organizations (HCOs) face serious problems such as fatal medical errors, harmful treatment delays, misuse of scarce nurses, costly inefficiency, and service failures. Some of health care managers' most critical work involves designing and structuring their organizations so their missions, visions, and goals can be achieved-and in some cases so their organizations can survive. Thus, it is imperative that graduate healthcare management programs develop effective approaches for teaching OT to students who will manage HCOs. Guided by principles of education, three applied teaching/learning activities/assignments were created to teach OT in a graduate healthcare management program. These educationalmethods develop students' competency with OT applied to HCOs. The teaching techniques in this article may be useful to faculty teaching graduate courses in organization theory and related subjects such as leadership, quality, and operation management. PMID:16566496
Method for applying photographic resists to otherwise incompatible substrates
NASA Technical Reports Server (NTRS)
Fuhr, W. (Inventor)
1981-01-01
A method for applying photographic resists to otherwise incompatible substrates, such as a baking enamel paint surface, is described wherein the uncured enamel paint surface is coated with a non-curing lacquer which is, in turn, coated with a partially cured lacquer. The non-curing lacquer adheres to the enamel and a photo resist material satisfactorily adheres to the partially cured lacquer. Once normal photo etching techniques are employed the lacquer coats can be easily removed from the enamel leaving the photo etched image. In the case of edge lighted instrument panels, a coat of uncured enamel is placed over the cured enamel followed by the lacquer coats and the photo resists which is exposed and developed. Once the etched uncured enamel is cured, the lacquer coats are removed leaving an etched panel.
NASA Astrophysics Data System (ADS)
Saito, Tatsuhito; Kondo, Keiichiro; Koseki, Takafumi
A DC-electrified railway system that is fed by diode rectifiers at a substation is unable to return the electric power to an AC grid. Accordingly, the braking cars have to restrict regenerative braking power when the power consumption of the powering cars is not sufficient. However, the characteristics of a DC-electrified railway system, including the powering cars, is not known, and a mathematical model for designing a controller has not been established yet. Hence, the object of this study is to obtain the mathematical model for an analytical design method of the regenerative braking control system. In the first part of this paper, the static characteristics of this system are presented to show the position of the equilibrium point. The linearization of this system at the equilibrium point is then performed to describe the dynamic characteristics of the system. An analytical design method is then proposed on the basis of these characteristics. The proposed design method is verified by experimental tests with a 1kW class miniature model, and numerical simulations.
Single-Case Designs and Qualitative Methods: Applying a Mixed Methods Research Perspective
ERIC Educational Resources Information Center
Hitchcock, John H.; Nastasi, Bonnie K.; Summerville, Meredith
2010-01-01
The purpose of this conceptual paper is to describe a design that mixes single-case (sometimes referred to as single-subject) and qualitative methods, hereafter referred to as a single-case mixed methods design (SCD-MM). Minimal attention has been given to the topic of applying qualitative methods to SCD work in the literature. These two…
ERIC Educational Resources Information Center
Dynarski, Mark; Betts, Julian; Feldman, Jill
2016-01-01
The DC Opportunity Scholarship Program (OSP), established in 2004, is the only federally-funded private school voucher program for low-income parents in the United States. This evaluation brief describes findings using data from more than 2,000 applicants' parents, who applied to the program from spring 2011 to spring 2013 following…
Random-breakage mapping method applied to human DNA sequences
NASA Technical Reports Server (NTRS)
Lobrich, M.; Rydberg, B.; Cooper, P. K.; Chatterjee, A. (Principal Investigator)
1996-01-01
The random-breakage mapping method [Game et al. (1990) Nucleic Acids Res., 18, 4453-4461] was applied to DNA sequences in human fibroblasts. The methodology involves NotI restriction endonuclease digestion of DNA from irradiated calls, followed by pulsed-field gel electrophoresis, Southern blotting and hybridization with DNA probes recognizing the single copy sequences of interest. The Southern blots show a band for the unbroken restriction fragments and a smear below this band due to radiation induced random breaks. This smear pattern contains two discontinuities in intensity at positions that correspond to the distance of the hybridization site to each end of the restriction fragment. By analyzing the positions of those discontinuities we confirmed the previously mapped position of the probe DXS1327 within a NotI fragment on the X chromosome, thus demonstrating the validity of the technique. We were also able to position the probes D21S1 and D21S15 with respect to the ends of their corresponding NotI fragments on chromosome 21. A third chromosome 21 probe, D21S11, has previously been reported to be close to D21S1, although an uncertainty about a second possible location existed. Since both probes D21S1 and D21S11 hybridized to a single NotI fragment and yielded a similar smear pattern, this uncertainty is removed by the random-breakage mapping method.
Turbulence profiling methods applied to ESO's adaptive optics facility
NASA Astrophysics Data System (ADS)
Valenzuela, Javier; Béchet, Clémentine; Garcia-Rissmann, Aurea; Gonté, Frédéric; Kolb, Johann; Le Louarn, Miska; Neichel, Benoît; Madec, Pierre-Yves; Guesalaga, Andrés.
2014-07-01
Two algorithms were recently studied for C2n profiling from wide-field Adaptive Optics (AO) measurements on GeMS (Gemini Multi-Conjugate AO system). They both rely on the Slope Detection and Ranging (SLODAR) approach, using spatial covariances of the measurements issued from various wavefront sensors. The first algorithm estimates the C2n profile by applying the truncated least-squares inverse of a matrix modeling the response of slopes covariances to various turbulent layer heights. In the second method, the profile is estimated by deconvolution of these spatial cross-covariances of slopes. We compare these methods in the new configuration of ESO Adaptive Optics Facility (AOF), a high-order multiple laser system under integration. For this, we use measurements simulated by the AO cluster of ESO. The impact of the measurement noise and of the outer scale of the atmospheric turbulence is analyzed. The important influence of the outer scale on the results leads to the development of a new step for outer scale fitting included in each algorithm. This increases the reliability and robustness of the turbulence strength and profile estimations.
Urban drainage control applying rational method and geographic information technologies
NASA Astrophysics Data System (ADS)
Aldalur, Beatriz; Campo, Alicia; Fernández, Sandra
2013-09-01
The objective of this study is to develop a method of controlling urban drainages in the town of Ingeniero White motivated by the problems arising as a result of floods, water logging and the combination of southeasterly and high tides. A Rational Method was applied to control urban watersheds and used tools of Geographic Information Technology (GIT). A Geographic Information System was developed on the basis of 28 panchromatic aerial photographs of 2005. They were georeferenced with control points measured with Global Positioning Systems (basin: 6 km2). Flow rates of basins and sub-basins were calculated and it was verified that the existing open channels have a low slope with the presence of permanent water and generate stagnation of water favored by the presence of trash. It is proposed for the output of storm drains, the use of an existing channel to evacuate the flow. The solution proposed in this work is complemented by the placement of three pumping stations: one on a channel to drain rain water which will allow the drain of the excess water from the lower area where is located the Ingeniero White city and the two others that will drain the excess liquid from the port area.
RAMSES: Applied research on separation methods using space electrophoresis
NASA Astrophysics Data System (ADS)
Jamin Changeart, F.; Faure, F.; Sanchez, V.; Schoot, B.; Simonis, M.; Renard, A.; Collete, J. P.; Perez, D.; Val, J. M.; de Olano, A. l.
Eight european industrial companies, the CNRS and University Paul Sabatier and CNES/ Centre National d'Etudes Spatiales collaborate on the SBS (Space Bio Separation) project which aims at demonstrating the possibility of preparing high-purity biomaterials under microgravity conditions. As a first step of SBS, the proposal of a cooperative flight of the RAMSES facility on board Spacelab during the IML-2 mission, scheduled January 1993, has been selected by NASA. RAMSES allows basic and applied research on free flow zone electrophoresis, in order to assess the influence of a low-gravity environment on the purification of biological products. Experiments will be performed by European and American scientists. The facility will be integrated in a Spacelab single rack. Using in situ diagnostics with a U.V. photometer and a cross illuminator, RAMSES investigates a wide variety of transport phenomena to better understand the basic mechanisms which govern electrophoresis method. RAMSES should be a basis for a more complete facility dedicated to the purification of biomaterials, associating various separation methods. This paper will provide an overview of this space facility RAMSES with emphasis on continuous flow zone electrophoresis technique, scientific back-ground, RAMSES experimental program, RAMSES main functions and an overall description of the RAMSES main units.
P, Rajeeva M.; S, Naveen C.; Lamani, Ashok R.; Jayanna, H. S.; Bothla, V Prasad
2015-06-24
Nanocrystalline tin oxide (SnO{sub 2}) material of different particle size was synthesized using gel combustion method by varying oxidizer (HNO{sub 3}) and keeping fuel as a constant. The prepared samples were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM) and Energy Dispersive Analysis X-ray Spectroscope (EDAX). The effect of oxidizer in the gel combustion method was investigated by inspecting the particle size of nano SnO{sub 2} powder. The particle size was found to be increases with the increase of oxidizer from 8 to 12 moles. The X-ray diffraction patterns of the calcined product showed the formation of high purity tetragonal tin (IV) oxide with the particle size in the range of 17 to 31 nm which was calculated by Scherer’s formula. The particles and temperature dependence of direct (DC) electrical conductivity of SnO{sub 2} nanomaterial was studied using Keithley source meter. The DC electrical conductivity of SnO{sub 2} nanomaterial increases with the temperature from 80 to 300K and decrease with the particle size at constant temperature.
Advanced Signal Processing Methods Applied to Digital Mammography
NASA Technical Reports Server (NTRS)
Stauduhar, Richard P.
1997-01-01
without further support. Task 5: Better modeling does indeed make an improvement in the detection output. After the proposal ended, we came up with some new theoretical explanations that helps in understanding when the D4 filter should be better. This work is currently in the review process. Task 6: N/A. This no longer applies in view of Tasks 4-5. Task 7: Comprehensive plans for further work have been completed. These plans are the subject of two proposals, one to NASA and one to HHS. These proposals represent plans for a complete evaluation of the methods for identifying normal mammograms, augmented with significant further theoretical work.
Applying sociodramatic methods in teaching transition to palliative care.
Baile, Walter F; Walters, Rebecca
2013-03-01
We introduce the technique of sociodrama, describe its key components, and illustrate how this simulation method was applied in a workshop format to address the challenge of discussing transition to palliative care. We describe how warm-up exercises prepared 15 learners who provide direct clinical care to patients with cancer for a dramatic portrayal of this dilemma. We then show how small-group brainstorming led to the creation of a challenging scenario wherein highly optimistic family members of a 20-year-old young man with terminal acute lymphocytic leukemia responded to information about the lack of further anticancer treatment with anger and blame toward the staff. We illustrate how the facilitators, using sociodramatic techniques of doubling and role reversal, helped learners to understand and articulate the hidden feelings of fear and loss behind the family's emotional reactions. By modeling effective communication skills, the facilitators demonstrated how key communication skills, such as empathic responses to anger and blame and using "wish" statements, could transform the conversation from one of conflict to one of problem solving with the family. We also describe how we set up practice dyads to give the learners an opportunity to try out new skills with each other. An evaluation of the workshop and similar workshops we conducted is presented. PMID:22889858
Hargrove, Douglas L.
2004-09-14
A portable, hand-held meter used to measure direct current (DC) attenuation in low impedance electrical signal cables and signal attenuators. A DC voltage is applied to the signal input of the cable and feedback to the control circuit through the signal cable and attenuators. The control circuit adjusts the applied voltage to the cable until the feedback voltage equals the reference voltage. The "units" of applied voltage required at the cable input is the system attenuation value of the cable and attenuators, which makes this meter unique. The meter may be used to calibrate data signal cables, attenuators, and cable-attenuator assemblies.
NASA Technical Reports Server (NTRS)
Mclyman, C. W.
1983-01-01
Compact dc/dc inverter uses single integrated-circuit package containing six inverter gates that generate and amplify 100-kHz square-wave switching signal. Square-wave switching inverts 10-volt local power to isolated voltage at another desired level. Relatively high operating frequency reduces size of filter capacitors required, resulting in small package unit.
A GIS modeling method applied to predicting forest songbird habitat
Dettmers, Randy; Bart, Jonathan
1999-01-01
We have developed an approach for using a??presencea?? data to construct habitat models. Presence data are those that indicate locations where the target organism is observed to occur, but that cannot be used to define locations where the organism does not occur. Surveys of highly mobile vertebrates often yield these kinds of data. Models developed through our approach yield predictions of the amount and the spatial distribution of good-quality habitat for the target species. This approach was developed primarily for use in a GIS context; thus, the models are spatially explicit and have the potential to be applied over large areas. Our method consists of two primary steps. In the first step, we identify an optimal range of values for each habitat variable to be used as a predictor in the model. To find these ranges, we employ the concept of maximizing the difference between cumulative distribution functions of (1) the values of a habitat variable at the observed presence locations of the target organism, and (2) the values of that habitat variable for all locations across a study area. In the second step, multivariate models of good habitat are constructed by combining these ranges of values, using the Boolean operators a??anda?? and a??or.a?? We use an approach similar to forward stepwise regression to select the best overall model. We demonstrate the use of this method by developing species-specific habitat models for nine forest-breeding songbirds (e.g., Cerulean Warbler, Scarlet Tanager, Wood Thrush) studied in southern Ohio. These models are based on speciesa?? microhabitat preferences for moisture and vegetation characteristics that can be predicted primarily through the use of abiotic variables. We use slope, land surface morphology, land surface curvature, water flow accumulation downhill, and an integrated moisture index, in conjunction with a land-cover classification that identifies forest/nonforest, to develop these models. The performance of these
NASA Astrophysics Data System (ADS)
Li, Bin; Zhang, Qin-Jian; Shi, Yan-Chao; Li, Jia-Jun; Li, Hong; Lu, Fan-Xiu; Chen, Guang-Chao
2014-08-01
A nano-crystlline diamond film is grown by the dc arcjet chemical vapor deposition method. The film is characterized by scanning electron microscopy, high-resolution transmission electron microscopy (HRTEM), x-ray diffraction (XRD) and Raman spectra, respectively. The nanocrystalline grains are averagely with 80 nm in the size measured by XRD, and further proven by Raman and HRTEM. The observed novel morphology of the growth surface, pineapple-like morphology, is constructed by cubo-octahedral growth zones with a smooth faceted top surface and coarse side surfaces. The as-grown film possesses (100) dominant surface containing a little amorphous sp2 component, which is far different from the nano-crystalline film with the usual cauliflower-like morphology.
Naveen, C. S. Jayanna, H. S. Lamani, Ashok R. Rajeeva, M. P.
2014-04-24
ZnO nanoparticles of different size were prepared by varying the molar ratio of glycine and zinc nitrate hexahydrate as fuel and oxidizer (F/O = 0.8, 1.11, 1.7) by simple solution combustion method. Powder samples were characterized by UV-Visible spectrophotometer, X-ray diffractometer, Scanning electron microscope (SEM). DC electrical conductivity measurements at room temperature and in the temperature range of 313-673K were carried out for the prepared thick films and it was found to increase with increase of temperature which confirms the semiconducting nature of the samples. Activation energies were calculated and it was found that, F/O molar ratio 1.7 has low E{sub AL} (Low temperature activation energy) and high E{sub AH} (High temperature activation energy) compared to other samples.
Technology Transfer Automated Retrieval System (TEKTRAN)
A comprehensive method for Vitamin D analysis has been developed by using the best aspects of currently available published methods. The comprehensive method can be applied to a wide range of food samples including dry breakfast cereal, diet supplement drinks, powdered infant formula, cheese and ot...
Early Oscillation Detection for DC/DC Converter Fault Diagnosis
NASA Technical Reports Server (NTRS)
Wang, Bright L.
2011-01-01
The electrical power system of a spacecraft plays a very critical role for space mission success. Such a modern power system may contain numerous hybrid DC/DC converters both inside the power system electronics (PSE) units and onboard most of the flight electronics modules. One of the faulty conditions for DC/DC converter that poses serious threats to mission safety is the random occurrence of oscillation related to inherent instability characteristics of the DC/DC converters and design deficiency of the power systems. To ensure the highest reliability of the power system, oscillations in any form shall be promptly detected during part level testing, system integration tests, flight health monitoring, and on-board fault diagnosis. The popular gain/phase margin analysis method is capable of predicting stability levels of DC/DC converters, but it is limited only to verification of designs and to part-level testing on some of the models. This method has to inject noise signals into the control loop circuitry as required, thus, interrupts the DC/DC converter's normal operation and increases risks of degrading and damaging the flight unit. A novel technique to detect oscillations at early stage for flight hybrid DC/DC converters was developed.
The method of characteristics applied to Stirling engines
Taylor, D.R.
1984-08-01
Since Finkelstein first proposed a method of solving the equations of continuity, momentum and energy in a rigorous fashion, most analysts have concentrated on the nodal method for simulating Stirling engines. Organ has proposed a set of isothermal equations which may be solved by the method of characteristics. A solution method, by Benson, of the full set of equations has been in use for several years for the analysis of diesel engines. This paper discusses the application of the method of characteristics to the simulation of Stirling cycle machines.
NASA Technical Reports Server (NTRS)
Gruber, R. P. (Inventor)
1984-01-01
A dc to dc converter which can start with a shorted output and which regulates output voltage and current is described. Voltage controlled switches directed current through the primary of a transformer the secondary of which includes virtual reactance. The switching frequency of the switches is appropriately varied to increase the voltage drop across the virtual reactance in the secondary winding to which there is connected a low impedance load. A starting circuit suitable for voltage switching devices is provided.
Nessa, Fazilatun; Ismail, Zhari; Karupiah, Sundram; Mohamed, Nornisah
2005-09-01
A selective and sensitive reversed-phase (RP) high-performance liquid chromatographic method is developed for the quantitative analysis of five naturally occurring flavonoids of Blumea balsamifera DC, namely dihydroquercetin-7,4'-dimethyl ether (DQDE), blumeatin (BL), quercetin (QN), 5,7,3',5'-tetrahydroxyflavanone (THFE), and dihydroquercetin-4'-methyl ether (DQME). These compounds have been isolated using various chromatographic methods. The five compounds are completely separated within 35 min using an RP C18, Nucleosil column and with an isocratic methanol-0.5% phosphoric acid (50:50, v/v) mobile phase at the flow rate of 0.9 mL/min. The separation of the compounds is monitored at 285 nm using UV detection. Identifications of specific flavonoids are made by comparing their retention times with those of the standards. Reproducibility of the method is good, with coefficients of variation of 1.48% for DQME, 2.25% for THFE, 2.31% for QN, 2.23% for DQDE, and 1.51% for BL. The average recoveries of pure flavonoids upon addition to lyophilized powder and subsequent extraction are 99.8% for DQME, 99.9% for THFE, 100.0% for BL, 100.6% for DQDE, and 97.4% for QN. PMID:16212782
ELECTROCHEMICAL METHODS APPLIED TO THE ANALYSIS OF ENVIRONMENTAL SAMPLES
The fundamental principles of electroanalytical methods based on potentiometry, coulometry, conductance, and voltammetry are reviewed, and examples are given of applications to environmental analyses.
The flow curvature method applied to canard explosion
NASA Astrophysics Data System (ADS)
Ginoux, Jean-Marc; Llibre, Jaume
2011-11-01
The aim of this work is to establish that the bifurcation parameter value leading to a canard explosion in dimension 2 obtained by the so-called geometric singular perturbation method can be found according to the flow curvature method. This result will be then exemplified with the classical Van der Pol oscillator.
Applying Statistical Methods To The Proton Radius Puzzle
NASA Astrophysics Data System (ADS)
Higinbotham, Douglas
2016-03-01
In recent nuclear physics publications, one can find many examples where chi2 and reduced chi2 are the only tools used for the selection of models even though a chi2 difference test is only meaningful for nested models. With this in mind, we reanalyze electron scattering data, being careful to clearly define our selection criteria as well as using a co-variance matrix and confidence levels as per the statistics section of the particle data book. We will show that when applying such techniques to hydrogen elastic scattering data, the nested models often require fewer parameters than typically used and that non-nested models are often rejected inappropriately.
Fabrication of LiCoO{sub 2} thin film cathodes by DC magnetron sputtering method
Noh, Jung-pil; Cho, Gyu-bong; Jung, Ki-taek; Kang, Won-gyeong; Ha, Chung-wan; Ahn, Hyo-jun; Ahn, Jou-Hyeon; Nam, Tae-hyun; Kim, Ki-won
2012-10-15
LiCoO{sub 2} thin films were fabricated on Al substrate by direct current magnetron sputtering method. The effects of Ar/O{sub 2} gas rates and annealing temperatures were investigated. Crystal structures and surface morphologies of the deposited films were investigated by X-ray diffraction, Raman scattering spectroscopy and field emission scanning electron microscopy. The as-deposited LiCoO{sub 2} thin films exhibited amorphous structure. The crystallization starts at the annealing temperature over 400 °C. However, the annealed films have the partially disordered structure without completely ordered crystalline structure even at 600 °C annealing. The electrochemical properties of the LiCoO{sub 2} films were investigated by the charge–discharge and cycle measurements. The 500 °C annealing film has the highest capacity retention rate of 78.2% at 100th cycles.
A Method to Apply Friction Modifier in Railway System
NASA Astrophysics Data System (ADS)
Matsumoto, Kosuke; Suda, Yoshihiro; Iwasa, Takashi; Fujii, Takeshi; Tomeoka, Masao; Tanimoto, Masuhisa; Kishimoto, Yasushi; Nakai, Takuji
Controlling the friction between wheel and rail is direct and very effective measures to improve the curving performances of bogie trucks, because the curving performances of bogie truck depend much on friction characteristics. Authors have proposed a method, “friction control”, which utilizes friction modifier (KELTRACKTM HPF) with onboard spraying system. With the method, not only friction coefficient, but also friction characteristics are able to be controlled as expected. In this paper, results of fundamental experiments are reported which play an important role to realize the new method.
EMD Method Applied to Identification of Logging Sequence Strata
NASA Astrophysics Data System (ADS)
Zhao, Ni; Li, Rui
2015-10-01
In this work, we compare Fourier transform, wavelet transform, and empirical mode decomposition (EMD), and point out that EMD method decomposes complex signal into a series of component functions through curves of local mean value. Each of Intrinsic Mode Functions (IMFs - component functions) contains all the information on the original signal. Therefore, it is more suitable for the interface identification of logging sequence strata. Well logging data reflect rich geological information and belong to non-linear and non-stationary signals and EMD method can deal with non-stationary and non-linear signals very well. By selecting sensitive parameters combination that reflects the regional geological structure and lithology, the combined parameter can be decomposed through EMD method to study the correlation and the physical meaning of each intrinsic mode function. Meanwhile, it identifies the stratigraphy and cycle sequence perfectly and provides an effective signal treatment method for sequence interface.
Spectral methods applied to fluidized bed combustors. Final report
Brown, R.C.; Christofides, N.J.; Junk, K.W.; Raines, T.S.; Thiede, T.D.
1996-08-01
The objective of this project was to develop methods for characterizing fuels and sorbents from time-series data obtained during transient operation of fluidized bed boilers. These methods aimed at determining time constants for devolatilization and char burnout using carbon dioxide (CO{sub 2}) profiles and from time constants for the calcination and sulfation processes using CO{sub 2} and sulfur dioxide (SO{sub 2}) profiles.
Newton like: Minimal residual methods applied to transonic flow calculations
NASA Technical Reports Server (NTRS)
Wong, Y. S.
1984-01-01
A computational technique for the solution of the full potential equation is presented. The method consists of outer and inner iterations. The outer iterate is based on a Newton like algorithm, and a preconditioned Minimal Residual method is used to seek an approximate solution of the system of linear equations arising at each inner iterate. The present iterative scheme is formulated so that the uncertainties and difficulties associated with many iterative techniques, namely the requirements of acceleration parameters and the treatment of additional boundary conditions for the intermediate variables, are eliminated. Numerical experiments based on the new method for transonic potential flows around the NACA 0012 airfoil at different Mach numbers and different angles of attack are presented, and these results are compared with those obtained by the Approximate Factorization technique. Extention to three dimensional flow calculations and application in finite element methods for fluid dynamics problems by the present method are also discussed. The Inexact Newton like method produces a smoother reduction in the residual norm, and the number of supersonic points and circulations are rapidly established as the number of iterations is increased.
Optimal Scheduling Method of Controllable Loads in DC Smart Apartment Building
NASA Astrophysics Data System (ADS)
Shimoji, Tsubasa; Tahara, Hayato; Matayoshi, Hidehito; Yona, Atsushi; Senjyu, Tomonobu
2015-12-01
From the perspective of global warming suppression and the depletion of energy resources, renewable energies, such as the solar collector (SC) and photovoltaic generation (PV), have been gaining attention in worldwide. Houses or buildings with PV and heat pumps (HPs) are recently being used in residential areas widely due to the time of use (TOU) electricity pricing scheme which is essentially inexpensive during middle-night and expensive during day-time. If fixed batteries and electric vehicles (EVs) can be introduced in the premises, the electricity cost would be even more reduced. While, if the occupants arbitrarily use these controllable loads respectively, power demand in residential buildings may fluctuate in the future. Thus, an optimal operation of controllable loads such as HPs, batteries and EV should be scheduled in the buildings in order to prevent power flow from fluctuating rapidly. This paper proposes an optimal scheduling method of controllable loads, and the purpose is not only the minimization of electricity cost for the consumers, but also suppression of fluctuation of power flow on the power supply side. Furthermore, a novel electricity pricing scheme is also suggested in this paper.
Genualdi, Susie; MacMahon, Shaun; Robbins, Katherine; Farris, Samantha; Shyong, Nicole; DeJager, Lowri
2016-01-01
Sudan I, II, III and IV dyes are banned for use as food colorants in the United States and European Union because they are toxic and carcinogenic. These dyes have been illegally used as food additives in products such as chilli spices and palm oil to enhance their red colour. From 2003 to 2005, the European Union made a series of decisions requiring chilli spices and palm oil imported to the European Union to contain analytical reports declaring them free of Sudan I–IV. In order for the USFDA to investigate the adulteration of palm oil and chilli spices with unapproved colour additives in the United States, a method was developed for the extraction and analysis of Sudan dyes in palm oil, and previous methods were validated for Sudan dyes in chilli spices. Both LC-DAD and LC-MS/MS methods were examined for their limitations and effectiveness in identifying adulterated samples. Method validation was performed for both chilli spices and palm oil by spiking samples known to be free of Sudan dyes at concentrations close to the limit of detection. Reproducibility, matrix effects, and selectivity of the method were also investigated. Additionally, for the first time a survey of palm oil and chilli spices was performed in the United States, specifically in the Washington, DC, area. Illegal dyes, primarily Sudan IV, were detected in palm oil at concentrations from 150 to 24 000 ng ml−1. Low concentrations (< 21 μg kg−1) of Sudan dyes were found in 11 out of 57 spices and are most likely a result of cross-contamination during preparation and storage and not intentional adulteration. PMID:26824489
Genualdi, Susie; MacMahon, Shaun; Robbins, Katherine; Farris, Samantha; Shyong, Nicole; DeJager, Lowri
2016-01-01
Sudan I, II, III and IV dyes are banned for use as food colorants in the United States and European Union because they are toxic and carcinogenic. These dyes have been illegally used as food additives in products such as chilli spices and palm oil to enhance their red colour. From 2003 to 2005, the European Union made a series of decisions requiring chilli spices and palm oil imported to the European Union to contain analytical reports declaring them free of Sudan I-IV. In order for the USFDA to investigate the adulteration of palm oil and chilli spices with unapproved colour additives in the United States, a method was developed for the extraction and analysis of Sudan dyes in palm oil, and previous methods were validated for Sudan dyes in chilli spices. Both LC-DAD and LC-MS/MS methods were examined for their limitations and effectiveness in identifying adulterated samples. Method validation was performed for both chilli spices and palm oil by spiking samples known to be free of Sudan dyes at concentrations close to the limit of detection. Reproducibility, matrix effects, and selectivity of the method were also investigated. Additionally, for the first time a survey of palm oil and chilli spices was performed in the United States, specifically in the Washington, DC, area. Illegal dyes, primarily Sudan IV, were detected in palm oil at concentrations from 150 to 24 000 ng ml(-1). Low concentrations (< 21 µg kg(-1)) of Sudan dyes were found in 11 out of 57 spices and are most likely a result of cross-contamination during preparation and storage and not intentional adulteration. PMID:26824489
NASA Astrophysics Data System (ADS)
Walker, E.; Glover, P. W. J.; Ruel, J.
2014-02-01
High-quality streaming potential coupling coefficient measurements have been carried out using a newly designed cell with both a steady state methodology and a new pressure transient approach. The pressure transient approach has shown itself to be particularly good at providing high-quality streaming potential coefficient measurements as each transient increase or decrease allows thousands of measurements to be made at different pressures to which a good linear regression can be fitted. Nevertheless, the transient method can be up to 5 times as fast as the conventional measurement approaches because data from all flow rates are taken in the same transient measurement rather than separately. Test measurements have been made on samples of Berea and Boise sandstone as a function of salinity (approximately 18 salinities between 10-5 mol/dm3 and 2 mol/dm3). The data have also been inverted to obtain the zeta potential. The streaming potential coefficient becomes greater (more negative) for fluids with lower salinities, which is consistent with existing measurements. Our measurements are also consistent with the high-salinity streaming potential coefficient measurements made by Vinogradov et al. (2010). Both the streaming potential coefficient and the zeta potential have also been modeled using the theoretical approach of Glover (2012). This modeling allows the microstructural, electrochemical, and fluid properties of the saturated rock to be taken into account in order to provide a relationship that is unique to each particular rock sample. In all cases, we found that the experimental data were a good match to the theoretical model.
Three-dimensional unstructured grid method applied to turbomachinery
NASA Technical Reports Server (NTRS)
Kwon, Oh Joon; Hah, Chunill
1993-01-01
This work has three objectives: to develop a three-dimensional flow solver based on unstructured tetrahedral meshes for turbomachinery flows; to validate the solver through comparisons with experimental data; and to apply the solver for better understanding of the flow through turbomachinery geometries and design improvement. The work followed three different approaches: an existing external flow solver/grid generator (USM3D/VGRID) was extensively modified for internal flows; a three-dimensional, finite-volume solver based on Roe's flux-difference splitting and explicit Runge-Kutta time stepping; and three-dimensional unstructured tetrahedral mesh generation using an advancing-front technique. A discussion of these topics is presented in viewgraph form.
The colour analysis method applied to homogeneous rocks
NASA Astrophysics Data System (ADS)
Halász, Amadé; Halmai, Ákos
2015-12-01
Computer-aided colour analysis can facilitate cyclostratigraphic studies. Here we report on a case study involving the development of a digital colour analysis method for examination of the Boda Claystone Formation which is the most suitable in Hungary for the disposal of high-level radioactive waste. Rock type colours are reddish brown or brownish red, or any shade between brown and red. The method presented here could be used to differentiate similar colours and to identify gradual transitions between these; the latter are of great importance in a cyclostratigraphic analysis of the succession. Geophysical well-logging has demonstrated the existence of characteristic cyclic units, as detected by colour and natural gamma. Based on our research, colour, natural gamma and lithology correlate well. For core Ib-4, these features reveal the presence of orderly cycles with thicknesses of roughly 0.64 to 13 metres. Once the core has been scanned, this is a time- and cost-effective method.
Variance reduction methods applied to deep-penetration problems
Cramer, S.N.
1984-01-01
All deep-penetration Monte Carlo calculations require variance reduction methods. Before beginning with a detailed approach to these methods, several general comments concerning deep-penetration calculations by Monte Carlo, the associated variance reduction, and the similarities and differences of these with regard to non-deep-penetration problems will be addressed. The experienced practitioner of Monte Carlo methods will easily find exceptions to any of these generalities, but it is felt that these comments will aid the novice in understanding some of the basic ideas and nomenclature. Also, from a practical point of view, the discussions and developments presented are oriented toward use of the computer codes which are presented in segments of this Monte Carlo course.
DAKOTA reliability methods applied to RAVEN/RELAP-7.
Swiler, Laura Painton; Mandelli, Diego; Rabiti, Cristian; Alfonsi, Andrea
2013-09-01
This report summarizes the result of a NEAMS project focused on the use of reliability methods within the RAVEN and RELAP-7 software framework for assessing failure probabilities as part of probabilistic risk assessment for nuclear power plants. RAVEN is a software tool under development at the Idaho National Laboratory that acts as the control logic driver and post-processing tool for the newly developed Thermal-Hydraulic code RELAP-7. Dakota is a software tool developed at Sandia National Laboratories containing optimization, sensitivity analysis, and uncertainty quantification algorithms. Reliability methods are algorithms which transform the uncertainty problem to an optimization problem to solve for the failure probability, given uncertainty on problem inputs and a failure threshold on an output response. The goal of this work is to demonstrate the use of reliability methods in Dakota with RAVEN/RELAP-7. These capabilities are demonstrated on a demonstration of a Station Blackout analysis of a simplified Pressurized Water Reactor (PWR).
Carr, F.L.; Terrill, L.R.
1987-01-20
A DC to DC battery charger is described for a vehicle comprising: adapter plug means for making electrical connections to a first battery through a cigarette lighter socket in the vehicle; means of making electrical connections to a second battery to be charged; a DC to AC converter and an AC to DC rectifier for elevating the voltage from the first battery to a voltage above that of the second battery; integrated circuit means for generating a pulse width modulated current as a function for the charged condition of the second battery; transistor switch means supplied with the pulse width modulated current for developing a charging voltage; a choke coil and a capacitor serially connected to the transistor switch means; and a diode connected across the choke coil and the capacitor whereby the capacitor is charged during pulses of current from the transistor switch means through the choke coil. The choke coil reverses polarity at the termination of the pulses of current and continues to charge the battery through the diode. The DC rectified voltage is controlled by the integrated circuit means for regulating current through the choke coil.
System Identification and POD Method Applied to Unsteady Aerodynamics
NASA Technical Reports Server (NTRS)
Tang, Deman; Kholodar, Denis; Juang, Jer-Nan; Dowell, Earl H.
2001-01-01
The representation of unsteady aerodynamic flow fields in terms of global aerodynamic modes has proven to be a useful method for reducing the size of the aerodynamic model over those representations that use local variables at discrete grid points in the flow field. Eigenmodes and Proper Orthogonal Decomposition (POD) modes have been used for this purpose with good effect. This suggests that system identification models may also be used to represent the aerodynamic flow field. Implicit in the use of a systems identification technique is the notion that a relative small state space model can be useful in describing a dynamical system. The POD model is first used to show that indeed a reduced order model can be obtained from a much larger numerical aerodynamical model (the vortex lattice method is used for illustrative purposes) and the results from the POD and the system identification methods are then compared. For the example considered, the two methods are shown to give comparable results in terms of accuracy and reduced model size. The advantages and limitations of each approach are briefly discussed. Both appear promising and complementary in their characteristics.
[Synchrotron-based characterization methods applied to ancient materials (I)].
Anheim, Étienne; Thoury, Mathieu; Bertrand, Loïc
2015-12-01
This article aims at presenting the first results of a transdisciplinary research programme in heritage sciences. Based on the growing use and on the potentialities of micro- and nano-characterization synchrotron-based methods to study ancient materials (archaeology, palaeontology, cultural heritage, past environments), this contribution will identify and test conceptual and methodological elements of convergence between physicochemical and historical sciences. PMID:25200450
Method for applying pyrolytic carbon coatings to small particles
Beatty, Ronald L.; Kiplinger, Dale V.; Chilcoat, Bill R.
1977-01-01
A method for coating small diameter, low density particles with pyrolytic carbon is provided by fluidizing a bed of particles wherein at least 50 per cent of the particles have a density and diameter of at least two times the remainder of the particles and thereafter recovering the small diameter and coated particles.
GENERAL CONSIDERATIONS FOR GEOPHYSICAL METHODS APPLIED TO AGRICULTURE
Technology Transfer Automated Retrieval System (TEKTRAN)
Geophysics is the application of physical quantity measurement techniques to provide information on conditions or features beneath the earth’s surface. With the exception of borehole geophysical methods and soil probes like a cone penetrometer, these techniques are generally noninvasive with physica...
Wang, A.C.; Sanders, S.R.
1993-10-01
The regular switching action of a pulsewidth modulated (PWM) circuit generates conducted and radiated electro-magnetic interference (EMI), and may also generate acoustical disturbances. Programmed pulsewidth modulation techniques have been applied suing various methods to control harmonics inherent in switched power circuits. In this paper, a method to generate an optimal programmed switching waveform for a dc-dc converter is presented. This switching waveform is optimized to reduce the amplitude of harmonic peaks in the EMI generated by the converter. Experimental results, a brief discussion of sensitivity, and a practical implementation of a circuit to generate the PWM waveform are given.
Current Human Reliability Analysis Methods Applied to Computerized Procedures
Ronald L. Boring
2012-06-01
Computerized procedures (CPs) are an emerging technology within nuclear power plant control rooms. While CPs have been implemented internationally in advanced control rooms, to date no US nuclear power plant has implemented CPs in its main control room (Fink et al., 2009). Yet, CPs are a reality of new plant builds and are an area of considerable interest to existing plants, which see advantages in terms of enhanced ease of use and easier records management by omitting the need for updating hardcopy procedures. The overall intent of this paper is to provide a characterization of human reliability analysis (HRA) issues for computerized procedures. It is beyond the scope of this document to propose a new HRA approach or to recommend specific methods or refinements to those methods. Rather, this paper serves as a review of current HRA as it may be used for the analysis and review of computerized procedures.
Paraxial WKB Method Applied to the Lower Hybrid Wave Propagation
Bertelli, N; Poli, E; Harvey, R; Wright, J C; Bonoli, P T; Phillips, C K; Simov, A P; Valeo, E
2012-07-12
The paraxial WKB (pWKB) approximation, also called beam tracing method, has been employed in order to study the propagation of lower hybrid (LH) waves in a tokamak plasma. Analogous to the well-know ray tracing method, this approach reduces Maxwell's equations to a set of ordinary differential equations, while, in addition, retains the effects of the finite beam cross-section, and, thus, the effects of diffraction. A new code, LHBEAM (Lower Hybrid BEAM tracing), is presented, which solves the pWKB equations in tokamak geometry for arbitrary launching conditions and for analytic and experimental plasma equilibria. In addition, LHBEAM includes linear electron Landau damping for the evaluation of the absorbed power density and the reconstruction of the wave electric field in both the physical and Fourier space. Illustrative LHBEAM calculations are presented along with a comparison with the ray tracing code GENRAY and the full wave solver TORIC-LH.
MONTE CARLO ERROR ESTIMATION APPLIED TO NONDESTRUCTIVE ASSAY METHODS
R. ESTEP; ET AL
2000-06-01
Monte Carlo randomization of nuclear counting data into N replicate sets is the basis of a simple and effective method for estimating error propagation through complex analysis algorithms such as those using neural networks or tomographic image reconstructions. The error distributions of properly simulated replicate data sets mimic those of actual replicate measurements and can be used to estimate the std. dev. for an assay along with other statistical quantities. We have used this technique to estimate the standard deviation in radionuclide masses determined using the tomographic gamma scanner (TGS) and combined thermal/epithermal neutron (CTEN) methods. The effectiveness of this approach is demonstrated by a comparison of our Monte Carlo error estimates with the error distributions in actual replicate measurements and simulations of measurements. We found that the std. dev. estimated this way quickly converges to an accurate value on average and has a predictable error distribution similar to N actual repeat measurements. The main drawback of the Monte Carlo method is that N additional analyses of the data are required, which may be prohibitively time consuming with slow analysis algorithms.
Differential correction method applied to measurement of the FAST reflector
NASA Astrophysics Data System (ADS)
Li, Xin-Yi; Zhu, Li-Chun; Hu, Jin-Wen; Li, Zhi-Heng
2016-08-01
The Five-hundred-meter Aperture Spherical radio Telescope (FAST) adopts an active deformable main reflector which is composed of 4450 triangular panels. During an observation, the illuminated area of the reflector is deformed into a 300-m diameter paraboloid and directed toward a source. To achieve accurate control of the reflector shape, positions of 2226 nodes distributed around the entire reflector must be measured with sufficient precision within a limited time, which is a challenging task because of the large scale. Measurement of the FAST reflector makes use of stations and node targets. However, in this case the effect of the atmosphere on measurement accuracy is a significant issue. This paper investigates a differential correction method for total stations measurement of the FAST reflector. A multi-benchmark differential correction method, including a scheme for benchmark selection and weight assignment, is proposed. On-site evaluation experiments show there is an improvement of 70%–80% in measurement accuracy compared with the uncorrected measurement, verifying the effectiveness of the proposed method.
NASA Technical Reports Server (NTRS)
Stolzer, Alan J.; Halford, Carl
2007-01-01
In a previous study, multiple regression techniques were applied to Flight Operations Quality Assurance-derived data to develop parsimonious model(s) for fuel consumption on the Boeing 757 airplane. The present study examined several data mining algorithms, including neural networks, on the fuel consumption problem and compared them to the multiple regression results obtained earlier. Using regression methods, parsimonious models were obtained that explained approximately 85% of the variation in fuel flow. In general data mining methods were more effective in predicting fuel consumption. Classification and Regression Tree methods reported correlation coefficients of .91 to .92, and General Linear Models and Multilayer Perceptron neural networks reported correlation coefficients of about .99. These data mining models show great promise for use in further examining large FOQA databases for operational and safety improvements.
Atomistic Method Applied to Computational Modeling of Surface Alloys
NASA Technical Reports Server (NTRS)
Bozzolo, Guillermo H.; Abel, Phillip B.
2000-01-01
The formation of surface alloys is a growing research field that, in terms of the surface structure of multicomponent systems, defines the frontier both for experimental and theoretical techniques. Because of the impact that the formation of surface alloys has on surface properties, researchers need reliable methods to predict new surface alloys and to help interpret unknown structures. The structure of surface alloys and when, and even if, they form are largely unpredictable from the known properties of the participating elements. No unified theory or model to date can infer surface alloy structures from the constituents properties or their bulk alloy characteristics. In spite of these severe limitations, a growing catalogue of such systems has been developed during the last decade, and only recently are global theories being advanced to fully understand the phenomenon. None of the methods used in other areas of surface science can properly model even the already known cases. Aware of these limitations, the Computational Materials Group at the NASA Glenn Research Center at Lewis Field has developed a useful, computationally economical, and physically sound methodology to enable the systematic study of surface alloy formation in metals. This tool has been tested successfully on several known systems for which hard experimental evidence exists and has been used to predict ternary surface alloy formation (results to be published: Garces, J.E.; Bozzolo, G.; and Mosca, H.: Atomistic Modeling of Pd/Cu(100) Surface Alloy Formation. Surf. Sci., 2000 (in press); Mosca, H.; Garces J.E.; and Bozzolo, G.: Surface Ternary Alloys of (Cu,Au)/Ni(110). (Accepted for publication in Surf. Sci., 2000.); and Garces, J.E.; Bozzolo, G.; Mosca, H.; and Abel, P.: A New Approach for Atomistic Modeling of Pd/Cu(110) Surface Alloy Formation. (Submitted to Appl. Surf. Sci.)). Ternary alloy formation is a field yet to be fully explored experimentally. The computational tool, which is based on
SHUFFLE: A New Statistical Bootstrap Method: Applied to Cosmological Filaments
NASA Astrophysics Data System (ADS)
Bhavsar, Suketu P.; Bharadwaj, Somnath; Sheth, Jatush V.
2003-05-01
We introduce Shuffle, a powerful statistical procedure devised by Bhavsar and Ling [1] to determine the true physical extent of the filaments in the Las Campanas Redshift Survey [LCRS]. At its heart, Shuffle falls in the category of bootstrap like methods [2]. We find that the longest physical filamentary structures in 5 of the 6 LCRS slices are longer than 50 h-1 Mpc but not quite extending to 70 h-1 Mpc. The -3 degree slice contains filamentary structure longer than 70 h-1 Mpc.
Error behaviour of multistep methods applied to unstable differential systems
NASA Technical Reports Server (NTRS)
Brown, R. L.
1978-01-01
The problem of modelling a dynamic system described by a system of ordinary differential equations which has unstable components for limited periods of time is discussed. It is shown that the global error in a multistep numerical method is the solution to a difference equation initial value problem, and the approximate solution is given for several popular multistep integration formulae. Inspection of the solution leads to the formulation of four criteria for integrators appropriate to unstable problems. A sample problem is solved numerically using three popular formulae and two different stepsizes to illustrate the appropriateness of the criteria.
System And Method Of Applying Energetic Ions For Sterlization
Schmidt, John A.
2002-06-11
A method of sterilization of a container is provided whereby a cold plasma is caused to be disposed near a surface to be sterilized, and the cold plasma is then subjected to a pulsed voltage differential for producing energized ions in the plasma. Those energized ions then operate to achieve spore destruction on the surface to be sterilized. Further, a system for sterilization of a container which includes a conductive or non-conductive container, a cold plasma in proximity to the container, and a high voltage source for delivering a pulsed voltage differential between an electrode and the container and across the cold plasma, is provided.
System and method of applying energetic ions for sterilization
Schmidt, John A.
2003-12-23
A method of sterilization of a container is provided whereby a cold plasma is caused to be disposed near a surface to be sterilized, and the cold plasma is then subjected to a pulsed voltage differential for producing energized ions in the plasma. Those energized ions then operate to achieve spore destruction on the surface to be sterilized. Further, a system for sterilization of a container which includes a conductive or non-conductive container, a cold plasma in proximity to the container, and a high voltage source for delivering a pulsed voltage differential between an electrode and the container and across the cold plasma, is provided.
Applied high resolution geophysical methods: Offshore geoengineering hazards
Trabant, P.K.
1984-01-01
This book is an examination of the purpose, methodology, equipment, and data interpretation of high-resolution geophysical methods, which are used to assess geological and manmade engineering hazards at offshore construction locations. It is a state-of-the-art review. Contents: 1. Introduction. 2. Maring geophysics, an overview. 3. Marine geotechnique, an overview. 4. Echo sounders. 5. Side scan sonar. 6. Subbottom profilers. 7. Seismic sources. 8. Single-channel seismic reflection systems. 9. Multifold acquisition and digital processing. 10. Marine magnetometers. 11. Marine geoengineering hazards. 12. Survey organization, navigation, and future developments. Appendix. Glossary. References. Index.
Algebraic multigrid methods applied to problems in computational structural mechanics
NASA Technical Reports Server (NTRS)
Mccormick, Steve; Ruge, John
1989-01-01
The development of algebraic multigrid (AMG) methods and their application to certain problems in structural mechanics are described with emphasis on two- and three-dimensional linear elasticity equations and the 'jacket problems' (three-dimensional beam structures). Various possible extensions of AMG are also described. The basic idea of AMG is to develop the discretization sequence based on the target matrix and not the differential equation. Therefore, the matrix is analyzed for certain dependencies that permit the proper construction of coarser matrices and attendant transfer operators. In this manner, AMG appears to be adaptable to structural analysis applications.
Microcanonical ensemble simulation method applied to discrete potential fluids.
Sastre, Francisco; Benavides, Ana Laura; Torres-Arenas, José; Gil-Villegas, Alejandro
2015-09-01
In this work we extend the applicability of the microcanonical ensemble simulation method, originally proposed to study the Ising model [A. Hüller and M. Pleimling, Int. J. Mod. Phys. C 13, 947 (2002)0129-183110.1142/S0129183102003693], to the case of simple fluids. An algorithm is developed by measuring the transition rates probabilities between macroscopic states, that has as advantage with respect to conventional Monte Carlo NVT (MC-NVT) simulations that a continuous range of temperatures are covered in a single run. For a given density, this new algorithm provides the inverse temperature, that can be parametrized as a function of the internal energy, and the isochoric heat capacity is then evaluated through a numerical derivative. As an illustrative example we consider a fluid composed of particles interacting via a square-well (SW) pair potential of variable range. Equilibrium internal energies and isochoric heat capacities are obtained with very high accuracy compared with data obtained from MC-NVT simulations. These results are important in the context of the application of the Hüller-Pleimling method to discrete-potential systems, that are based on a generalization of the SW and square-shoulder fluids properties. PMID:26465582
Steered Molecular Dynamics Methods Applied to Enzyme Mechanism and Energetics.
Ramírez, C L; Martí, M A; Roitberg, A E
2016-01-01
One of the main goals of chemistry is to understand the underlying principles of chemical reactions, in terms of both its reaction mechanism and the thermodynamics that govern it. Using hybrid quantum mechanics/molecular mechanics (QM/MM)-based methods in combination with a biased sampling scheme, it is possible to simulate chemical reactions occurring inside complex environments such as an enzyme, or aqueous solution, and determining the corresponding free energy profile, which provides direct comparison with experimental determined kinetic and equilibrium parameters. Among the most promising biasing schemes is the multiple steered molecular dynamics method, which in combination with Jarzynski's Relationship (JR) allows obtaining the equilibrium free energy profile, from a finite set of nonequilibrium reactive trajectories by exponentially averaging the individual work profiles. However, obtaining statistically converged and accurate profiles is far from easy and may result in increased computational cost if the selected steering speed and number of trajectories are inappropriately chosen. In this small review, using the extensively studied chorismate to prephenate conversion reaction, we first present a systematic study of how key parameters such as pulling speed, number of trajectories, and reaction progress are related to the resulting work distributions and in turn the accuracy of the free energy obtained with JR. Second, and in the context of QM/MM strategies, we introduce the Hybrid Differential Relaxation Algorithm, and show how it allows obtaining more accurate free energy profiles using faster pulling speeds and smaller number of trajectories and thus smaller computational cost. PMID:27497165
Statistical methods for texture analysis applied to agronomical images
NASA Astrophysics Data System (ADS)
Cointault, F.; Journaux, L.; Gouton, P.
2008-02-01
For activities of agronomical research institute, the land experimentations are essential and provide relevant information on crops such as disease rate, yield components, weed rate... Generally accurate, they are manually done and present numerous drawbacks, such as penibility, notably for wheat ear counting. In this case, the use of color and/or texture image processing to estimate the number of ears per square metre can be an improvement. Then, different image segmentation techniques based on feature extraction have been tested using textural information with first and higher order statistical methods. The Run Length method gives the best results closed to manual countings with an average error of 3%. Nevertheless, a fine justification of hypothesis made on the values of the classification and description parameters is necessary, especially for the number of classes and the size of analysis windows, through the estimation of a cluster validity index. The first results show that the mean number of classes in wheat image is of 11, which proves that our choice of 3 is not well adapted. To complete these results, we are currently analysing each of the class previously extracted to gather together all the classes characterizing the ears.
Applied methods to verify LP turbine performance after retrofit
Overby, R.; Lindberg, G.
1996-12-31
With increasing operational hours of power plants, many utilities may find it necessary to replace turbine components, i.e., low pressure turbines. In order to decide between different technical and economic solutions, the utility often takes the opportunity to choose between an OEM or non-OEM supplier. This paper will deal with the retrofitting of LP turbines. Depending on the scope of supply the contract must define the amount of improvement and specifically how to verify this improvement. Unfortunately, today`s Test Codes, such as ASME PTC 6 and 6.1, do not satisfactorily cover these cases. The methods used by Florida Power and Light (FP and L) and its supplier to verify the improvement of the low pressure turbine retrofit at the Martin No. 1 and Sanford No. 4 units will be discussed and the experience gained will be presented. In particular the influence of the thermal cycle on the applicability of the available methods will be analyzed and recommendations given.
Microcanonical ensemble simulation method applied to discrete potential fluids
NASA Astrophysics Data System (ADS)
Sastre, Francisco; Benavides, Ana Laura; Torres-Arenas, José; Gil-Villegas, Alejandro
2015-09-01
In this work we extend the applicability of the microcanonical ensemble simulation method, originally proposed to study the Ising model [A. Hüller and M. Pleimling, Int. J. Mod. Phys. C 13, 947 (2002), 10.1142/S0129183102003693], to the case of simple fluids. An algorithm is developed by measuring the transition rates probabilities between macroscopic states, that has as advantage with respect to conventional Monte Carlo NVT (MC-NVT) simulations that a continuous range of temperatures are covered in a single run. For a given density, this new algorithm provides the inverse temperature, that can be parametrized as a function of the internal energy, and the isochoric heat capacity is then evaluated through a numerical derivative. As an illustrative example we consider a fluid composed of particles interacting via a square-well (SW) pair potential of variable range. Equilibrium internal energies and isochoric heat capacities are obtained with very high accuracy compared with data obtained from MC-NVT simulations. These results are important in the context of the application of the Hüller-Pleimling method to discrete-potential systems, that are based on a generalization of the SW and square-shoulder fluids properties.
Artificial Intelligence Methods Applied to Parameter Detection of Atrial Fibrillation
NASA Astrophysics Data System (ADS)
Arotaritei, D.; Rotariu, C.
2015-09-01
In this paper we present a novel method to develop an atrial fibrillation (AF) based on statistical descriptors and hybrid neuro-fuzzy and crisp system. The inference of system produce rules of type if-then-else that care extracted to construct a binary decision system: normal of atrial fibrillation. We use TPR (Turning Point Ratio), SE (Shannon Entropy) and RMSSD (Root Mean Square of Successive Differences) along with a new descriptor, Teager- Kaiser energy, in order to improve the accuracy of detection. The descriptors are calculated over a sliding window that produce very large number of vectors (massive dataset) used by classifier. The length of window is a crisp descriptor meanwhile the rest of descriptors are interval-valued type. The parameters of hybrid system are adapted using Genetic Algorithm (GA) algorithm with fitness single objective target: highest values for sensibility and sensitivity. The rules are extracted and they are part of the decision system. The proposed method was tested using the Physionet MIT-BIH Atrial Fibrillation Database and the experimental results revealed a good accuracy of AF detection in terms of sensitivity and specificity (above 90%).
The Movable Type Method Applied to Protein-Ligand Binding
Zheng, Zheng; Ucisik, Melek N.; Merz, Kenneth M.
2013-01-01
Accurately computing the free energy for biological processes like protein folding or protein-ligand association remains a challenging problem. Both describing the complex intermolecular forces involved and sampling the requisite configuration space make understanding these processes innately difficult. Herein, we address the sampling problem using a novel methodology we term “movable type”. Conceptually it can be understood by analogy with the evolution of printing and, hence, the name movable type. For example, a common approach to the study of protein-ligand complexation involves taking a database of intact drug-like molecules and exhaustively docking them into a binding pocket. This is reminiscent of early woodblock printing where each page had to be laboriously created prior to printing a book. However, printing evolved to an approach where a database of symbols (letters, numerals, etc.) was created and then assembled using a movable type system, which allowed for the creation of all possible combinations of symbols on a given page, thereby, revolutionizing the dissemination of knowledge. Our movable type (MT) method involves the identification of all atom pairs seen in protein-ligand complexes and then creating two databases: one with their associated pairwise distant dependent energies and another associated with the probability of how these pairs can combine in terms of bonds, angles, dihedrals and non-bonded interactions. Combining these two databases coupled with the principles of statistical mechanics allows us to accurately estimate binding free energies as well as the pose of a ligand in a receptor. This method, by its mathematical construction, samples all of configuration space of a selected region (the protein active site here) in one shot without resorting to brute force sampling schemes involving Monte Carlo, genetic algorithms or molecular dynamics simulations making the methodology extremely efficient. Importantly, this method explores the
The Movable Type Method Applied to Protein-Ligand Binding.
Zheng, Zheng; Ucisik, Melek N; Merz, Kenneth M
2013-12-10
Accurately computing the free energy for biological processes like protein folding or protein-ligand association remains a challenging problem. Both describing the complex intermolecular forces involved and sampling the requisite configuration space make understanding these processes innately difficult. Herein, we address the sampling problem using a novel methodology we term "movable type". Conceptually it can be understood by analogy with the evolution of printing and, hence, the name movable type. For example, a common approach to the study of protein-ligand complexation involves taking a database of intact drug-like molecules and exhaustively docking them into a binding pocket. This is reminiscent of early woodblock printing where each page had to be laboriously created prior to printing a book. However, printing evolved to an approach where a database of symbols (letters, numerals, etc.) was created and then assembled using a movable type system, which allowed for the creation of all possible combinations of symbols on a given page, thereby, revolutionizing the dissemination of knowledge. Our movable type (MT) method involves the identification of all atom pairs seen in protein-ligand complexes and then creating two databases: one with their associated pairwise distant dependent energies and another associated with the probability of how these pairs can combine in terms of bonds, angles, dihedrals and non-bonded interactions. Combining these two databases coupled with the principles of statistical mechanics allows us to accurately estimate binding free energies as well as the pose of a ligand in a receptor. This method, by its mathematical construction, samples all of configuration space of a selected region (the protein active site here) in one shot without resorting to brute force sampling schemes involving Monte Carlo, genetic algorithms or molecular dynamics simulations making the methodology extremely efficient. Importantly, this method explores the free
Data Reduction Methods Applied to the Fastrac Engine
NASA Technical Reports Server (NTRS)
Santi, L. Michael
1999-01-01
The Fastrac rocket engine is currently being developed for the X-34 technology demonstrator vehicle. The engine performance model must be calibrated to support accurate performance prediction. Data reduction is the process of estimating hardware characteristics from available test data, and is essential for effective performance model calibration and prediction. A new data reduction procedure was developed, implemented, and tested using data from Fastrac engine tests. The procedure selects hardware and test measurements to use in the reduction process based on examination of the model influence matrix condition number. Predicted hardware characteristics are recovered from the solution of a quadratic programming problem. Computational tests indicate that the new procedure provides a significant improvement in test data reduction capability. Enhancements include improved test data utilization and time history data reduction capability. The new method is generically applicable to other systems.
Use Conditions and Efficiency Measurements of DC Power Optimizers for Photovoltaic Systems: Preprint
Deline, C.; MacAlpine, S.
2013-10-01
No consensus standard exists for estimating annual conversion efficiency of DC-DC converters or power optimizers in photovoltaic (PV) applications. The performance benefits of PV power electronics including per-panel DC-DC converters depend in large part on the operating conditions of the PV system, along with the performance characteristics of the power optimizer itself. This work presents acase study of three system configurations that take advantage of the capabilities of DC power optimizers. Measured conversion efficiencies of DC-DC converters are applied to these scenarios to determine the annual weighted operating efficiency. A simplified general method of reporting weighted efficiency is given, based on the California Energy Commission's CEC efficiency rating and severalinput / output voltage ratios. Efficiency measurements of commercial power optimizer products are presented using the new performance metric, along with a description of the limitations of the approach.
Applying the partitioned multiobjective risk method (PMRM) to portfolio selection.
Reyes Santos, Joost; Haimes, Yacov Y
2004-06-01
The analysis of risk-return tradeoffs and their practical applications to portfolio analysis paved the way for Modern Portfolio Theory (MPT), which won Harry Markowitz a 1992 Nobel Prize in Economics. A typical approach in measuring a portfolio's expected return is based on the historical returns of the assets included in a portfolio. On the other hand, portfolio risk is usually measured using volatility, which is derived from the historical variance-covariance relationships among the portfolio assets. This article focuses on assessing portfolio risk, with emphasis on extreme risks. To date, volatility is a major measure of risk owing to its simplicity and validity for relatively small asset price fluctuations. Volatility is a justified measure for stable market performance, but it is weak in addressing portfolio risk under aberrant market fluctuations. Extreme market crashes such as that on October 19, 1987 ("Black Monday") and catastrophic events such as the terrorist attack of September 11, 2001 that led to a four-day suspension of trading on the New York Stock Exchange (NYSE) are a few examples where measuring risk via volatility can lead to inaccurate predictions. Thus, there is a need for a more robust metric of risk. By invoking the principles of the extreme-risk-analysis method through the partitioned multiobjective risk method (PMRM), this article contributes to the modeling of extreme risks in portfolio performance. A measure of an extreme portfolio risk, denoted by f(4), is defined as the conditional expectation for a lower-tail region of the distribution of the possible portfolio returns. This article presents a multiobjective problem formulation consisting of optimizing expected return and f(4), whose solution is determined using Evolver-a software that implements a genetic algorithm. Under business-as-usual market scenarios, the results of the proposed PMRM portfolio selection model are found to be compatible with those of the volatility-based model
Integrated Research Methods for Applied Urban Hydrogeology of Karst Sites
NASA Astrophysics Data System (ADS)
Epting, J.; Romanov, D. K.; Kaufmann, G.; Huggenberger, P.
2008-12-01
measures. Theories describing the evolution of karst systems are mainly based on conceptual models. Although these models are based on fundamental and well established physical and chemical principles that allow studying important processes from initial small scale fracture networks to the mature karst, systems for monitoring the evolution of karst phenomena are rare. Integrated process-oriented investigation methods are presented, comprising the combination of multiple data sources (lithostratigraphic information of boreholes, extensive groundwater monitoring, dye tracer tests, geophysics) with high-resolution numerical groundwater modeling and model simulations of karstification below the dam. Subsequently, different scenarios evaluated the future development of the groundwater flow regime, the karstification processes as well as possible remediation measures. The approach presented assists in optimizing investigation methods, including measurement and monitoring technologies with predictive character for similar subsidence problems within karst environments in urban areas.
Taguchi methods applied to oxygen-enriched diesel engine experiments
Marr, W.W.; Sekar, R.R.; Cole, R.L.; Marciniak, T.J. ); Longman, D.E. )
1992-01-01
This paper describes a test series conducted on a six-cylinder diesel engine to study the impacts of controlled factors (i.e., oxygen content of the combustion air, water content of the fuel, fuel rate, and fuel-injection timing) on engine emissions using Taguchi methods. Three levels of each factor were used in the tests. Only the main effects of the factors were examined; no attempt was made to analyze the interactions among the factors. It was found that, as in the case of the single-cylinder engine tests, oxygen in the combustion air was very effective in reducing particulate and smoke emissions. Increases in NO[sub x] due to the oxygen enrichment observed in the single-cylinder tests also occurred in the present six-cylinder tests. Water in the emulsified fuel was found to be much less effective in decreasing NO[sub x] emissions for the six-cylinder engine than it was for the single-cylinder engine.
Taguchi methods applied to oxygen-enriched diesel engine experiments
Marr, W.W.; Sekar, R.R.; Cole, R.L.; Marciniak, T.J.; Longman, D.E.
1992-12-01
This paper describes a test series conducted on a six-cylinder diesel engine to study the impacts of controlled factors (i.e., oxygen content of the combustion air, water content of the fuel, fuel rate, and fuel-injection timing) on engine emissions using Taguchi methods. Three levels of each factor were used in the tests. Only the main effects of the factors were examined; no attempt was made to analyze the interactions among the factors. It was found that, as in the case of the single-cylinder engine tests, oxygen in the combustion air was very effective in reducing particulate and smoke emissions. Increases in NO{sub x} due to the oxygen enrichment observed in the single-cylinder tests also occurred in the present six-cylinder tests. Water in the emulsified fuel was found to be much less effective in decreasing NO{sub x} emissions for the six-cylinder engine than it was for the single-cylinder engine.
Applying dynamic methods in off-line signature recognition
NASA Astrophysics Data System (ADS)
Igarza, Juan Jose; Hernaez, Inmaculada; Goirizelaia, Inaki; Espinosa, Koldo
2004-08-01
In this paper we present the work developed on off-line signature verification using Hidden Markov Models (HMM). HMM is a well-known technique used by other biometric features, for instance, in speaker recognition and dynamic or on-line signature verification. Our goal here is to extend Left-to-Right (LR)-HMM to the field of static or off-line signature processing using results provided by image connectivity analysis. The chain encoding of perimeter points for each blob obtained by this analysis is an ordered set of points in the space, clockwise around the perimeter of the blob. We discuss two different ways of generating the models depending on the way the blobs obtained from the connectivity analysis are ordered. In the first proposed method, blobs are ordered according to their perimeter length. In the second proposal, blobs are ordered in their natural reading order, i.e. from the top to the bottom and left to right. Finally, two LR-HMM models are trained using the parameters obtained by the mentioned techniques. Verification results of the two techniques are compared and some improvements are proposed.
A Probabilistic Design Method Applied to Smart Composite Structures
NASA Technical Reports Server (NTRS)
Shiao, Michael C.; Chamis, Christos C.
1995-01-01
A probabilistic design method is described and demonstrated using a smart composite wing. Probabilistic structural design incorporates naturally occurring uncertainties including those in constituent (fiber/matrix) material properties, fabrication variables, structure geometry and control-related parameters. Probabilistic sensitivity factors are computed to identify those parameters that have a great influence on a specific structural reliability. Two performance criteria are used to demonstrate this design methodology. The first criterion requires that the actuated angle at the wing tip be bounded by upper and lower limits at a specified reliability. The second criterion requires that the probability of ply damage due to random impact load be smaller than an assigned value. When the relationship between reliability improvement and the sensitivity factors is assessed, the results show that a reduction in the scatter of the random variable with the largest sensitivity factor (absolute value) provides the lowest failure probability. An increase in the mean of the random variable with a negative sensitivity factor will reduce the failure probability. Therefore, the design can be improved by controlling or selecting distribution parameters associated with random variables. This can be implemented during the manufacturing process to obtain maximum benefit with minimum alterations.
Random particle methods applied to broadband fan interaction noise
NASA Astrophysics Data System (ADS)
Dieste, M.; Gabard, G.
2012-10-01
Predicting broadband fan noise is key to reduce noise emissions from aircraft and wind turbines. Complete CFD simulations of broadband fan noise generation remain too expensive to be used routinely for engineering design. A more efficient approach consists in synthesizing a turbulent velocity field that captures the main features of the exact solution. This synthetic turbulence is then used in a noise source model. This paper concentrates on predicting broadband fan noise interaction (also called leading edge noise) and demonstrates that a random particle mesh method (RPM) is well suited for simulating this source mechanism. The linearized Euler equations are used to describe sound generation and propagation. In this work, the definition of the filter kernel is generalized to include non-Gaussian filters that can directly follow more realistic energy spectra such as the ones developed by Liepmann and von Kármán. The velocity correlation and energy spectrum of the turbulence are found to be well captured by the RPM. The acoustic predictions are successfully validated against Amiet's analytical solution for a flat plate in a turbulent stream. A standard Langevin equation is used to model temporal decorrelation, but the presence of numerical issues leads to the introduction and validation of a second-order Langevin model.
Mesoscopic electronics beyond DC transport
NASA Astrophysics Data System (ADS)
di Carlo, Leonardo
Since the inception of mesoscopic electronics in the 1980's, direct current (dc) measurements have underpinned experiments in quantum transport. Novel techniques complementing dc transport are becoming paramount to new developments in mesoscopic electronics, particularly as the road is paved toward quantum information processing. This thesis describes seven experiments on GaAs/AlGaAs and graphene nanostructures unified by experimental techniques going beyond traditional dc transport. Firstly, dc current induced by microwave radiation applied to an open chaotic quantum dot is investigated. Asymmetry of mesoscopic fluctuations of induced current in perpendicular magnetic field is established as a tool for separating the quantum photovoltaic effect from classical rectification. A differential charge sensing technique is next developed using integrated quantum point contacts to resolve the spatial distribution of charge inside a double quantum clot. An accurate method for determining interdot tunnel coupling and electron temperature using charge sensing is demonstrated. A two-channel system for detecting current noise in mesoscopic conductors is developed, enabling four experiments where shot noise probes transmission properties not available in dc transport and Johnson noise serves as an electron thermometer. Suppressed shot noise is observed in quantum point contacts at zero parallel magnetic field, associated with the 0.7 structure in conductance. This suppression evolves with increasing field into the shot-noise signature of spin-lifted mode degeneracy. Quantitative agreement is found with a phenomenological model for density-dependent mode splitting. Shot noise measurements of multi-lead quantum-dot structures in the Coulomb blockade regime distill the mechanisms by which Coulomb interaction and quantum indistinguishability correlate electron flow. Gate-controlled sign reversal of noise cross correlation in two capacitively-coupled dots is observed, and shown to
7 CFR 632.16 - Methods of applying planned land use and treatment.
Code of Federal Regulations, 2013 CFR
2013-01-01
... 7 Agriculture 6 2013-01-01 2013-01-01 false Methods of applying planned land use and treatment... Qualifications § 632.16 Methods of applying planned land use and treatment. (a) Land users may arrange to apply... administer a contract to perform the required treatment in accordance with 41 CFR chapters I and IV....
7 CFR 632.16 - Methods of applying planned land use and treatment.
Code of Federal Regulations, 2012 CFR
2012-01-01
... 7 Agriculture 6 2012-01-01 2012-01-01 false Methods of applying planned land use and treatment... Qualifications § 632.16 Methods of applying planned land use and treatment. (a) Land users may arrange to apply... administer a contract to perform the required treatment in accordance with 41 CFR chapters I and IV....
7 CFR 632.16 - Methods of applying planned land use and treatment.
Code of Federal Regulations, 2010 CFR
2010-01-01
... 7 Agriculture 6 2010-01-01 2010-01-01 false Methods of applying planned land use and treatment... Qualifications § 632.16 Methods of applying planned land use and treatment. (a) Land users may arrange to apply... administer a contract to perform the required treatment in accordance with 41 CFR chapters I and IV....
7 CFR 632.16 - Methods of applying planned land use and treatment.
Code of Federal Regulations, 2011 CFR
2011-01-01
... 7 Agriculture 6 2011-01-01 2011-01-01 false Methods of applying planned land use and treatment... Qualifications § 632.16 Methods of applying planned land use and treatment. (a) Land users may arrange to apply... administer a contract to perform the required treatment in accordance with 41 CFR chapters I and IV....
NASA Astrophysics Data System (ADS)
Urabe, Keiichiro; Shirai, Naoki; Tomita, Kentaro; Akiyama, Tsuyoshi; Murakami, Tomoyuki
2016-08-01
The density and temperature of electrons and key heavy particles were measured in an atmospheric-pressure pulsed-dc helium discharge plasma with a nitrogen molecular impurity generated using system with a liquid or metal anode and a metal cathode. To obtain these parameters, we conducted experiments using several laser-aided methods: Thomson scattering spectroscopy to obtain the spatial profiles of electron density and temperature, Raman scattering spectroscopy to obtain the neutral molecular nitrogen rotational temperature, phase-modulated dispersion interferometry to determine the temporal variation of the electron density, and time-resolved laser absorption spectroscopy to analyze the temporal variation of the helium metastable atom density. The electron density and temperature measured by Thomson scattering varied from 2.4 × 1014 cm‑3 and 1.8 eV at the center of the discharge to 0.8 × 1014 cm‑3 and 1.5 eV near the outer edge of the plasma in the case of the metal anode, respectively. The electron density obtained with the liquid anode was approximately 20% smaller than that obtained with the metal anode, while the electron temperature was not significantly affected by the anode material. The molecular nitrogen rotational temperatures were 1200 K with the metal anode and 1650 K with the liquid anode at the outer edge of the plasma column. The density of helium metastable atoms decreased by a factor of two when using the liquid anode.
Rundle, T.A.
1983-10-07
Hydrofracturing tests are to be performed to obtain experimental data regarding the magnitudes and orientations of the principal stresses in candidate repository horizons within the reference repository location (RRL). The tests are to be conducted in boreholes RRL-6 and DC-4 located in the reference repository location on the Hanford Site. This series of tests is to be limited to the performance of a maximum of 16 tests in each borehole. Basalt flows to be tested in borehole RRL-6 include the Rocky Coulee, Cohassett, McCoy Canyon, and Umtanum. Testing in borehole DC-4 will be in the Rocky Coulee and Cohassett basalt flows.
Analysis of self-oscillating dc-to-dc converters
NASA Technical Reports Server (NTRS)
Burger, P.
1974-01-01
The basic operational characteristics of dc-to-dc converters are analyzed along with the basic physical characteristics of power converters. A simple class of dc-to-dc power converters are chosen which could satisfy any set of operating requirements, and three different controlling methods in this class are described in detail. Necessary conditions for the stability of these converters are measured through analog computer simulation whose curves are related to other operational characteristics, such as ripple and regulation. Further research is suggested for the solution of absolute stability and efficient physical design of this class of power converters.
Near-infrared radiation curable multilayer coating systems and methods for applying same
Bowman, Mark P; Verdun, Shelley D; Post, Gordon L
2015-04-28
Multilayer coating systems, methods of applying and related substrates are disclosed. The coating system may comprise a first coating comprising a near-IR absorber, and a second coating deposited on a least a portion of the first coating. Methods of applying a multilayer coating composition to a substrate may comprise applying a first coating comprising a near-IR absorber, applying a second coating over at least a portion of the first coating and curing the coating with near infrared radiation.
ERIC Educational Resources Information Center
Cohen, Ayala; Nahum-Shani, Inbal; Doveh, Etti
2010-01-01
In their seminal paper, Edwards and Parry (1993) presented the polynomial regression as a better alternative to applying difference score in the study of congruence. Although this method is increasingly applied in congruence research, its complexity relative to other methods for assessing congruence (e.g., difference score methods) was one of the…
Radiation-Tolerant DC-DC Converters
NASA Technical Reports Server (NTRS)
Skutt, Glenn; Sable, Dan; Leslie, Leonard; Graham, Shawn
2012-01-01
A document discusses power converters suitable for space use that meet the DSCC MIL-PRF-38534 Appendix G radiation hardness level P classification. A method for qualifying commercially produced electronic parts for DC-DC converters per the Defense Supply Center Columbus (DSCC) radiation hardened assurance requirements was developed. Development and compliance testing of standard hybrid converters suitable for space use were completed for missions with total dose radiation requirements of up to 30 kRad. This innovation provides the same overall performance as standard hybrid converters, but includes assurance of radiation- tolerant design through components and design compliance testing. This availability of design-certified radiation-tolerant converters can significantly reduce total cost and delivery time for power converters for space applications that fit the appropriate DSCC classification (30 kRad).
Full wave dc-to-dc converter using energy storage transformers
NASA Technical Reports Server (NTRS)
Moore, E. T.; Wilson, T. G.
1969-01-01
Full wave dc-to-dc converter, for an ion thrustor, uses energy storage transformers to provide a method of dc-to-dc conversion and regulation. The converter has a high degree of physical simplicity, is lightweight and has high efficiency.
NASA Astrophysics Data System (ADS)
Kimura, Akira
In inverter-converter driving systems for AC electric cars, the DC input voltage of an inverter contains a ripple component with a frequency that is twice as high as the line voltage frequency, because of a single-phase converter. The ripple component of the inverter input voltage causes pulsations on torques and currents of driving motors. To decrease the pulsations, a beat-less control method, which modifies a slip frequency depending on the ripple component, is applied to the inverter control. In the present paper, the beat-less control method was analyzed in the frequency domain. In the first step of the analysis, transfer functions, which revealed the relationship among the ripple component of the inverter input voltage, the slip frequency, the motor torque pulsation and the current pulsation, were derived with a synchronous rotating model of induction motors. An analysis model of the beat-less control method was then constructed using the transfer functions. The optimal setting of the control method was obtained according to the analysis model. The transfer functions and the analysis model were verified through simulations.
NASA Technical Reports Server (NTRS)
Hamilton, H. B.; Strangas, E.
1980-01-01
The time dependent solution of the magnetic field is introduced as a method for accounting for the variation, in time, of the machine parameters in predicting and analyzing the performance of the electrical machines. The method of time dependent finite element was used in combination with an also time dependent construction of a grid for the air gap region. The Maxwell stress tensor was used to calculate the airgap torque from the magnetic vector potential distribution. Incremental inductances were defined and calculated as functions of time, depending on eddy currents and saturation. The currents in all the machine circuits were calculated in the time domain based on these inductances, which were continuously updated. The method was applied to a chopper controlled DC series motor used for electric vehicle drive, and to a salient pole sychronous motor with damper bars. Simulation results were compared to experimentally obtained ones.
Eom, Ji Mi; Oh, Hyun Gon; Cho, Il Hwan; Kwon, Sang Jik; Cho, Eou Sik
2013-11-01
Niobium oxide (Nb2O5) films were deposited on p-type Si wafers and sodalime glasses at a room temperature using in-line pulsed-DC magnetron sputtering system with various duty ratios. The different duty ratio was obtained by varying the reverse voltage time of pulsed DC power from 0.5 to 2.0 micros at the fixed frequency of 200 kHz. From the structural and optical characteristics of the sputtered NbOx films, it was possible to obtain more uniform and coherent NbOx films in case of the higher reverse voltage time as a result of the cleaning effect on the Nb2O5 target surface. The electrical characteristics from the metal-insulator-semiconductor (MIS) fabricated with the NbOx films shows the leakage currents are influenced by the reverse voltage time and the Schottky barrier diode characteristics. PMID:24245329
High-mobility ZrInO thin-film transistor prepared by an all-DC-sputtering method at room temperature
Xiao, Peng; Dong, Ting; Lan, Linfeng; Lin, Zhenguo; Song, Wei; Luo, Dongxiang; Xu, Miao; Peng, Junbiao
2016-01-01
Thin-film transistors (TFTs) with zirconium-doped indium oxide (ZrInO) semiconductor were successfully fabricated by an all-DC-sputtering method at room temperature. The ZrInO TFT without any intentionally annealing steps exhibited a high saturation mobility of 25.1 cm2V−1s−1. The threshold voltage shift was only 0.35 V for the ZrInO TFT under positive gate bias stress for 1 hour. Detailed studies showed that the room-temperature ZrInO thin film was in the amorphous state with low carrier density because of the strong bonding strength of Zr-O. The room-temperature process is attractive for its compatibility with almost all kinds of the flexible substrates, and the DC sputtering process is good for the production efficiency improvement and the fabrication cost reduction. PMID:27118177
Xiao, Peng; Dong, Ting; Lan, Linfeng; Lin, Zhenguo; Song, Wei; Luo, Dongxiang; Xu, Miao; Peng, Junbiao
2016-01-01
Thin-film transistors (TFTs) with zirconium-doped indium oxide (ZrInO) semiconductor were successfully fabricated by an all-DC-sputtering method at room temperature. The ZrInO TFT without any intentionally annealing steps exhibited a high saturation mobility of 25.1 cm(2)V(-1)s(-1). The threshold voltage shift was only 0.35 V for the ZrInO TFT under positive gate bias stress for 1 hour. Detailed studies showed that the room-temperature ZrInO thin film was in the amorphous state with low carrier density because of the strong bonding strength of Zr-O. The room-temperature process is attractive for its compatibility with almost all kinds of the flexible substrates, and the DC sputtering process is good for the production efficiency improvement and the fabrication cost reduction. PMID:27118177
High-mobility ZrInO thin-film transistor prepared by an all-DC-sputtering method at room temperature
NASA Astrophysics Data System (ADS)
Xiao, Peng; Dong, Ting; Lan, Linfeng; Lin, Zhenguo; Song, Wei; Luo, Dongxiang; Xu, Miao; Peng, Junbiao
2016-04-01
Thin-film transistors (TFTs) with zirconium-doped indium oxide (ZrInO) semiconductor were successfully fabricated by an all-DC-sputtering method at room temperature. The ZrInO TFT without any intentionally annealing steps exhibited a high saturation mobility of 25.1 cm2V‑1s‑1. The threshold voltage shift was only 0.35 V for the ZrInO TFT under positive gate bias stress for 1 hour. Detailed studies showed that the room-temperature ZrInO thin film was in the amorphous state with low carrier density because of the strong bonding strength of Zr-O. The room-temperature process is attractive for its compatibility with almost all kinds of the flexible substrates, and the DC sputtering process is good for the production efficiency improvement and the fabrication cost reduction.
Rajeeva, M. P. Jayanna, H. S. Ashok, R. L.; Naveen, C. S.; Bothla, V. Prasad
2014-04-24
Nanocrystalline Tin oxide material with different grain size was synthesized using gel combustion method by varying the fuel (C{sub 6}H{sub 8}O{sub 7}) to oxidizer (HNO{sub 3}) molar ratio by keeping the amount of fuel as constant. The prepared samples were characterized by using X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM) and Energy Dispersive Analysis X-ray Spectroscopy (EDAX). The effect of fuel to oxidizer molar ratio in the gel combustion method was investigated by inspecting the grain size of nano SnO{sub 2} powder. The grain size was found to be reduced with the amount of oxidizer increases from 0 to 6 moles in the step of 2. The X-ray diffraction patterns of the calcined product showed the formation of high purity tetragonal tin (IV) oxide with the grain size in the range of 12 to 31 nm which was calculated by Scherer's formula. Molar ratio and temperature dependence of DC electrical conductivity of SnO{sub 2} nanomaterial was studied using Keithley source meter. DC electrical conductivity of SnO{sub 2} nanomaterial increases with the temperature from 80K to 300K. From the study it was observed that the DC electrical conductivity of SnO{sub 2} nanomaterial decreases with the grain size at constant temperature.
Analysis of Monte Carlo methods applied to blackbody and lower emissivity cavities.
Pahl, Robert J; Shannon, Mark A
2002-02-01
Monte Carlo methods are often applied to the calculation of the apparent emissivities of blackbody cavities. However, for cavities with complex as well as some commonly encountered geometries, the emission Monte Carlo method experiences problems of convergence. The emission and absorption Monte Carlo methods are compared on the basis of ease of implementation and convergence speed when applied to blackbody sources. A new method to determine solution convergence compatible with both methods is developed, and the convergence speeds of the two methods are compared through the application of both methods to a right-circular cylinder cavity. It is shown that the absorption method converges faster and is easier to implement than the emission method when applied to most blackbody and lower emissivity cavities. PMID:11993915
Efficient Design in a DC to DC Converter Unit
NASA Technical Reports Server (NTRS)
Bruemmer, Joel E.; Williams, Fitch R.; Schmitz, Gregory V.
2002-01-01
Space Flight hardware requires high power conversion efficiencies due to limited power availability and weight penalties of cooling systems. The International Space Station (ISS) Electric Power System (EPS) DC-DC Converter Unit (DDCU) power converter is no exception. This paper explores the design methods and tradeoffs that were utilized to accomplish high efficiency in the DDCU. An isolating DC to DC converter was selected for the ISS power system because of requirements for separate primary and secondary grounds and for a well-regulated secondary output voltage derived from a widely varying input voltage. A flyback-current-fed push-pull topology or improved Weinberg circuit was chosen for this converter because of its potential for high efficiency and reliability. To enhance efficiency, a non-dissipative snubber circuit for the very-low-Rds-on Field Effect Transistors (FETs) was utilized, redistributing the energy that could be wasted during the switching cycle of the power FETs. A unique, low-impedance connection system was utilized to improve contact resistance over a bolted connection. For improved consistency in performance and to lower internal wiring inductance and losses a planar bus system is employed. All of these choices contributed to the design of a 6.25 KW regulated dc to dc converter that is 95 percent efficient. The methodology used in the design of this DC to DC Converter Unit may be directly applicable to other systems that require a conservative approach to efficient power conversion and distribution.
Early Oscillation Detection Technique for Hybrid DC/DC Converters
NASA Technical Reports Server (NTRS)
Wang, Bright L.
2011-01-01
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.
Single event AC - DC electrospraying
NASA Astrophysics Data System (ADS)
Stachewicz, U.; Dijksman, J. F.; Marijnissen, J. C. M.
2008-12-01
Electrospraying is an innovative method to deposit very small amounts of, for example, biofluids (far less than 1 p1) that include DNA or protein molecules. An electric potential is applied between a nozzle filled with liquid and a counter electrode placed at 1-2 millimeter distance from the nozzle. In our set-up we use an AC field superposed on a DC field to control the droplet generation process. Our approach is to create single events of electrospraying triggered by one single AC pulse. During this pulse, the equilibrium meniscus (determined by surface tension, static pressure and the DC field) of the liquid changes rapidly into a cone and subsequently into a jet formed at the cone apex. Next, the jet breaks-up into fine droplets and the spraying stops. The meniscus returns to its equilibrium shape again. So far we obtained a stable and reproducible single event process for ethanol and ethylene glycol with water using glass pipettes. The results will be used to generate droplets on demand in a controlled way and deposit them on a pre-defined place on the substrate.
High-Efficiency dc/dc Converter
NASA Technical Reports Server (NTRS)
Sturman, J.
1982-01-01
High-efficiency dc/dc converter has been developed that provides commonly used voltages of plus or minus 12 Volts from an unregulated dc source of from 14 to 40 Volts. Unique features of converter are its high efficiency at low power level and ability to provide output either larger or smaller than input voltage.
An Aural Learning Project: Assimilating Jazz Education Methods for Traditional Applied Pedagogy
ERIC Educational Resources Information Center
Gamso, Nancy M.
2011-01-01
The Aural Learning Project (ALP) was developed to incorporate jazz method components into the author's classical practice and her applied woodwind lesson curriculum. The primary objective was to place a more focused pedagogical emphasis on listening and hearing than is traditionally used in the classical applied curriculum. The components of the…
Optimum Design of CMOS DC-DC Converter for Mobile Applications
NASA Astrophysics Data System (ADS)
Katayama, Yasushi; Edo, Masaharu; Denta, Toshio; Kawashima, Tetsuya; Ninomiya, Tamotsu
In recent years, low output power CMOS DC-DC converters which integrate power stage MOSFETs and a PWM controller using CMOS process have been used in many mobile applications. In this paper, we propose the calculation method of CMOS DC-DC converter efficiency and report optimum design of CMOS DC-DC converter based on this method. By this method, converter efficiencies are directly calculated from converter specifications, dimensions of power stage MOSFET and device parameters. Therefore, this method can be used for optimization of CMOS DC-DC converter design, such as dimensions of power stage MOSFET and switching frequency. The efficiency calculated by the proposed method agrees well with the experimental results.
Method of error analysis for phase-measuring algorithms applied to photoelasticity.
Quiroga, J A; González-Cano, A
1998-07-10
We present a method of error analysis that can be applied for phase-measuring algorithms applied to photoelasticity. We calculate the contributions to the measurement error of the different elements of a circular polariscope as perturbations of the Jones matrices associated with each element. The Jones matrix of the real polariscope can then be calculated as a sum of the nominal matrix and a series of contributions that depend on the errors associated with each element separately. We apply this method to the analysis of phase-measuring algorithms for the determination of isoclinics and isochromatics, including comparisons with real measurements. PMID:18285900
Daud, Muhamad Zalani; Mohamed, Azah; Hannan, M. A.
2014-01-01
This paper presents an evaluation of an optimal DC bus voltage regulation strategy for grid-connected photovoltaic (PV) system with battery energy storage (BES). The BES is connected to the PV system DC bus using a DC/DC buck-boost converter. The converter facilitates the BES power charge/discharge to compensate for the DC bus voltage deviation during severe disturbance conditions. In this way, the regulation of DC bus voltage of the PV/BES system can be enhanced as compared to the conventional regulation that is solely based on the voltage-sourced converter (VSC). For the grid side VSC (G-VSC), two control methods, namely, the voltage-mode and current-mode controls, are applied. For control parameter optimization, the simplex optimization technique is applied for the G-VSC voltage- and current-mode controls, including the BES DC/DC buck-boost converter controllers. A new set of optimized parameters are obtained for each of the power converters for comparison purposes. The PSCAD/EMTDC-based simulation case studies are presented to evaluate the performance of the proposed optimized control scheme in comparison to the conventional methods. PMID:24883374
Daud, Muhamad Zalani; Mohamed, Azah; Hannan, M A
2014-01-01
This paper presents an evaluation of an optimal DC bus voltage regulation strategy for grid-connected photovoltaic (PV) system with battery energy storage (BES). The BES is connected to the PV system DC bus using a DC/DC buck-boost converter. The converter facilitates the BES power charge/discharge to compensate for the DC bus voltage deviation during severe disturbance conditions. In this way, the regulation of DC bus voltage of the PV/BES system can be enhanced as compared to the conventional regulation that is solely based on the voltage-sourced converter (VSC). For the grid side VSC (G-VSC), two control methods, namely, the voltage-mode and current-mode controls, are applied. For control parameter optimization, the simplex optimization technique is applied for the G-VSC voltage- and current-mode controls, including the BES DC/DC buck-boost converter controllers. A new set of optimized parameters are obtained for each of the power converters for comparison purposes. The PSCAD/EMTDC-based simulation case studies are presented to evaluate the performance of the proposed optimized control scheme in comparison to the conventional methods. PMID:24883374
Czosnek, Cezary; Bućko, Mirosław M.; Janik, Jerzy F.; Olejniczak, Zbigniew; Bystrzejewski, Michał; Łabędź, Olga; Huczko, Andrzej
2015-03-15
Highlights: • Make-up of the SiC-based nanopowders is a function of the C:Si:O ratio in precursor. • Two-stage aerosol-assisted synthesis offers conditions close to equilibrium. • DC thermal plasma synthesis yields kinetically controlled SiC products. - Abstract: Nanosized SiC-based powders were prepared from selected liquid-phase organosilicon precursors by the aerosol-assisted synthesis, the DC thermal plasma synthesis, and a combination of the two methods. The two-stage aerosol-assisted synthesis method provides at the end conditions close to thermodynamic equilibrium. The single-stage thermal plasma method is characterized by short particle residence times in the reaction zone, which can lead to kinetically controlled products. The by-products and final nanopowders were characterized by powder XRD, infrared spectroscopy FT-IR, scanning electron microscopy SEM, and {sup 29}Si MAS NMR spectroscopy. BET specific surface areas of the products were determined by standard physical adsorption of nitrogen at 77 K. The major component in all synthesis routes was found to be cubic silicon carbide β-SiC with average crystallite sizes ranging from a few to tens of nanometers. In some cases, it was accompanied by free carbon, elemental silicon or silica nanoparticles. The final mesoporous β-SiC-based nanopowders have a potential as affordable catalyst supports.
DC-Compensated Current Transformer.
Ripka, Pavel; Draxler, Karel; Styblíková, Renata
2016-01-01
Instrument current transformers (CTs) measure AC currents. The DC component in the measured current can saturate the transformer and cause gross error. We use fluxgate detection and digital feedback compensation of the DC flux to suppress the overall error to 0.15%. This concept can be used not only for high-end CTs with a nanocrystalline core, but it also works for low-cost CTs with FeSi cores. The method described here allows simultaneous measurements of the DC current component. PMID:26805830
Algebraic parameters identification of DC motors: methodology and analysis
NASA Astrophysics Data System (ADS)
Becedas, J.; Mamani, G.; Feliu, V.
2010-10-01
A fast, non-asymptotic, algebraic parameter identification method is applied to an uncertain DC motor to estimate the uncertain parameters: viscous friction coefficient and inertia. In this work, the methodology is developed and analysed, its convergence, a comparative study between the traditional recursive least square method and the algebraic identification method is carried out, and an analysis of the estimator in a noisy system is presented. Computer simulations were carried out to validate the suitability of the identification algorithm.
NASA Astrophysics Data System (ADS)
Radeva, Veselka S.
Several interactive methods, applied in the astronomy education during creation of the project about a colony in the Space, are presented. The methods Pyramid, Brainstorm, Snow-slip (Snowball) and Aquarium give the opportunity for schooler to understand and learn well a large packet of astronomical knowledge.
Methods for Smoothing Expectancy Tables Applied to the Prediction of Success in College
ERIC Educational Resources Information Center
Perrin, David W.; Whitney, Douglas R.
1976-01-01
The gains in accuracy resulting from applying any of the smoothing methods appear sufficient to justify the suggestion that all expectancy tables used by colleges for admission, guidance, or planning purposes should be smoothed. These methods on the average, reduce the criterion measure (an index of inaccuracy) by 30 percent. (Author/MV)
An Empirical Study of Applying Associative Method in College English Vocabulary Learning
ERIC Educational Resources Information Center
Zhang, Min
2014-01-01
Vocabulary is the basis of any language learning. To many Chinese non-English majors it is difficult to memorize English words. This paper applied associative method in presenting new words to them. It is found that associative method did receive a better result both in short-term and long-term retention of English words. Compared with the…
7 CFR 632.16 - Methods of applying planned land use and treatment.
Code of Federal Regulations, 2014 CFR
2014-01-01
... 7 Agriculture 6 2014-01-01 2014-01-01 false Methods of applying planned land use and treatment. 632.16 Section 632.16 Agriculture Regulations of the Department of Agriculture (Continued) NATURAL RESOURCES CONSERVATION SERVICE, DEPARTMENT OF AGRICULTURE LONG TERM CONTRACTING RURAL ABANDONED MINE PROGRAM Qualifications § 632.16 Methods of...
METHODS FOR EVALUATING THE BIOLOGICAL IMPACT OF POTENTIALLY TOXIC WASTE APPLIED TO SOILS
The study was designed to evaluate two methods that can be used to estimate the biological impact of organics and inorganics that may be in wastes applied to land for treatment and disposal. The two methods were the contact test and the artificial soil test. The contact test is a...
Accurate Simulation of MPPT Methods Performance When Applied to Commercial Photovoltaic Panels
2015-01-01
A new, simple, and quick-calculation methodology to obtain a solar panel model, based on the manufacturers' datasheet, to perform MPPT simulations, is described. The method takes into account variations on the ambient conditions (sun irradiation and solar cells temperature) and allows fast MPPT methods comparison or their performance prediction when applied to a particular solar panel. The feasibility of the described methodology is checked with four different MPPT methods applied to a commercial solar panel, within a day, and under realistic ambient conditions. PMID:25874262
Accurate simulation of MPPT methods performance when applied to commercial photovoltaic panels.
Cubas, Javier; Pindado, Santiago; Sanz-Andrés, Ángel
2015-01-01
A new, simple, and quick-calculation methodology to obtain a solar panel model, based on the manufacturers' datasheet, to perform MPPT simulations, is described. The method takes into account variations on the ambient conditions (sun irradiation and solar cells temperature) and allows fast MPPT methods comparison or their performance prediction when applied to a particular solar panel. The feasibility of the described methodology is checked with four different MPPT methods applied to a commercial solar panel, within a day, and under realistic ambient conditions. PMID:25874262
Active Problem Solving and Applied Research Methods in a Graduate Course on Numerical Methods
ERIC Educational Resources Information Center
Maase, Eric L.; High, Karen A.
2008-01-01
"Chemical Engineering Modeling" is a first-semester graduate course traditionally taught in a lecture format at Oklahoma State University. The course as taught by the author for the past seven years focuses on numerical and mathematical methods as necessary skills for incoming graduate students. Recent changes to the course have included Visual…
NASA Astrophysics Data System (ADS)
Ando, Yoshinobu; Eguchi, Yuya; Mizukawa, Makoto
In this research, we proposed and evaluated a management method of college mechatronics education. We applied the project management to college mechatronics education. We practiced our management method to the seminar “Microcomputer Seminar” for 3rd grade students who belong to Department of Electrical Engineering, Shibaura Institute of Technology. We succeeded in management of Microcomputer Seminar in 2006. We obtained the good evaluation for our management method by means of questionnaire.
NASA Technical Reports Server (NTRS)
Atkins, H. L.; Shu, Chi-Wang
2001-01-01
The explicit stability constraint of the discontinuous Galerkin method applied to the diffusion operator decreases dramatically as the order of the method is increased. Block Jacobi and block Gauss-Seidel preconditioner operators are examined for their effectiveness at accelerating convergence. A Fourier analysis for methods of order 2 through 6 reveals that both preconditioner operators bound the eigenvalues of the discrete spatial operator. Additionally, in one dimension, the eigenvalues are grouped into two or three regions that are invariant with order of the method. Local relaxation methods are constructed that rapidly damp high frequencies for arbitrarily large time step.
A study of two statistical methods as applied to shuttle solid rocket booster expenditures
NASA Technical Reports Server (NTRS)
Perlmutter, M.; Huang, Y.; Graves, M.
1974-01-01
The state probability technique and the Monte Carlo technique are applied to finding shuttle solid rocket booster expenditure statistics. For a given attrition rate per launch, the probable number of boosters needed for a given mission of 440 launches is calculated. Several cases are considered, including the elimination of the booster after a maximum of 20 consecutive launches. Also considered is the case where the booster is composed of replaceable components with independent attrition rates. A simple cost analysis is carried out to indicate the number of boosters to build initially, depending on booster costs. Two statistical methods were applied in the analysis: (1) state probability method which consists of defining an appropriate state space for the outcome of the random trials, and (2) model simulation method or the Monte Carlo technique. It was found that the model simulation method was easier to formulate while the state probability method required less computing time and was more accurate.
WU, TIANLIANG; ZANG, HONGCHENG
2016-01-01
The ultrasound probe and advancement of the needle during real-time ultrasound-assisted guidance of catheterization of the right internal jugular vein (RIJV) tend to collapse the vein, which reduces the success rate of the procedure. We have developed a novel puncture point-traction method (PPTM) to facilitate RIJV cannulation. The present study examined whether this method facilitated the performance of RIJV catheterization in anesthetized patients. In this study, 120 patients were randomly assigned to a group in which PPTM was performed (PPTM group, n=60) or a group in which it was not performed (non-PPTM group, n=60). One patient was excluded because of internal carotid artery puncture and 119 patients remained for analysis. The cross-sectional area (CSA), anteroposterior diameter (AD) and transverse diameter (TD) of the RIJV at the cricoid cartilage level following the induction of anesthesia and during catheterization were measured, and the number with obvious loss of resistance (NOLR), the number with easy aspiration of blood into syringe (NEABS) during advancement of the needle, and the number of first-pass punctures (NFPP) during catheterization were determined. In the non-PPTM group, the CSA was smaller during catheterization compared with that following the induction of anesthesia (P<0.01). In the PPTM group compared with the non-PPTM group during catheterization, the CSA was larger (P<0.01) and the AD (P<0.01) and TD (P<0.05) were wider; NOLR (P<0.01), NEABS (P<0.01) and NFPP (P<0.01) increased significantly. The findings from this study confirmed that the PPTM facilitated catheterization of the RIJV and improved the success rate of RIJV catheterization in anesthetized patients in the supine position. PMID:27347054
Applying Item Response Theory Methods to Design a Learning Progression-Based Science Assessment
ERIC Educational Resources Information Center
Chen, Jing
2012-01-01
Learning progressions are used to describe how students' understanding of a topic progresses over time and to classify the progress of students into steps or levels. This study applies Item Response Theory (IRT) based methods to investigate how to design learning progression-based science assessments. The research questions of this study are: (1)…
NASA Astrophysics Data System (ADS)
Evtushenko, Yu. G.; Posypkin, M. A.
2013-02-01
The nonuniform covering method is applied to multicriteria optimization problems. The ɛ-Pareto set is defined, and its properties are examined. An algorithm for constructing an ɛ-Pareto set with guaranteed accuracy ɛ is described. The efficiency of implementing this approach is discussed, and numerical results are presented.
A Method of Measuring the Costs and Benefits of Applied Research.
ERIC Educational Resources Information Center
Sprague, John W.
The Bureau of Mines studied the application of the concepts and methods of cost-benefit analysis to the problem of ranking alternative applied research projects. Procedures for measuring the different classes of project costs and benefits, both private and public, are outlined, and cost-benefit calculations are presented, based on the criteria of…
Small, Joshua; Fruehling, Adam; Garg, Anurag; Liu, Xiaoguang; Peroulis, Dimitrios
2014-01-01
Mechanically underdamped electrostatic fringing-field MEMS actuators are well known for their fast switching operation in response to a unit step input bias voltage. However, the tradeoff for the improved switching performance is a relatively long settling time to reach each gap height in response to various applied voltages. Transient applied bias waveforms are employed to facilitate reduced switching times for electrostatic fringing-field MEMS actuators with high mechanical quality factors. Removing the underlying substrate of the fringing-field actuator creates the low mechanical damping environment necessary to effectively test the concept. The removal of the underlying substrate also a has substantial improvement on the reliability performance of the device in regards to failure due to stiction. Although DC-dynamic biasing is useful in improving settling time, the required slew rates for typical MEMS devices may place aggressive requirements on the charge pumps for fully-integrated on-chip designs. Additionally, there may be challenges integrating the substrate removal step into the back-end-of-line commercial CMOS processing steps. Experimental validation of fabricated actuators demonstrates an improvement of 50x in switching time when compared to conventional step biasing results. Compared to theoretical calculations, the experimental results are in good agreement. PMID:25145811
Small, Joshua; Fruehling, Adam; Garg, Anurag; Liu, Xiaoguang; Peroulis, Dimitrios
2014-01-01
Mechanically underdamped electrostatic fringing-field MEMS actuators are well known for their fast switching operation in response to a unit step input bias voltage. However, the tradeoff for the improved switching performance is a relatively long settling time to reach each gap height in response to various applied voltages. Transient applied bias waveforms are employed to facilitate reduced switching times for electrostatic fringing-field MEMS actuators with high mechanical quality factors. Removing the underlying substrate of the fringing-field actuator creates the low mechanical damping environment necessary to effectively test the concept. The removal of the underlying substrate also a has substantial improvement on the reliability performance of the device in regards to failure due to stiction. Although DC-dynamic biasing is useful in improving settling time, the required slew rates for typical MEMS devices may place aggressive requirements on the charge pumps for fully-integrated on-chip designs. Additionally, there may be challenges integrating the substrate removal step into the back-end-of-line commercial CMOS processing steps. Experimental validation of fabricated actuators demonstrates an improvement of 50x in switching time when compared to conventional step biasing results. Compared to theoretical calculations, the experimental results are in good agreement. PMID:25145811
Kannan, R; Ramakrishna, T V; Rajagopalan, S R
1985-05-01
A method is described for the sequential determination of phosphorus, arsenic and silicon at ng/ml levels by d.c. polarography. These elements are converted into their heteropolymolybdates and separated by selective solvent extraction. Determination of the molybdenum in the extract gives an enhancement factor of 12 for determination of the hetero-atom. A further enhancement by a factor of 40 is achieved by determining the molybdenum by catalytic polarography in nitrate medium. Charging-current compensation is employed to improve precision and the detection limit. The detection limits for phosphorus, arsenic and silicon are 0.5, 4.7 and 3.1 mu/gl., respectively and the relative standard deviation is 2-2.5%. PMID:18963870
NASA Astrophysics Data System (ADS)
Mohamed, Galal A.; Mohamed, El-Maghraby; Abu El-Fadl, A.
2001-12-01
Thin films of zinc oxide doped with Zn 1- xLi xO with x=0.2 (ZnO : Li), have been prepared on sapphire, MgO and quartz substrates by DC magnetron sputtering method at 5 mTorr. The substrate temperatures were fixed to about 573 K. We have measured the transmission and reflection spectra and determined the absorption coefficient, optical band-gap ( Egdopt), the high frequency dielectric constant ε‧ ∞ and the carrier concentration N for the as-prepared films at room temperature. The films show direct allowed optical transitions with Egdopt values of 3.38, 3.43 and 3.29 eV for films deposited on sapphire, MgO and quartz substrates, respectively. The dependence of the obtained results on the substrate type are discussed.
The application of standardized control and interface circuits to three dc to dc power converters.
NASA Technical Reports Server (NTRS)
Yu, Y.; Biess, J. J.; Schoenfeld, A. D.; Lalli, V. R.
1973-01-01
Standardized control and interface circuits were applied to the three most commonly used dc to dc converters: the buck-boost converter, the series-switching buck regulator, and the pulse-modulated parallel inverter. The two-loop ASDTIC regulation control concept was implemented by using a common analog control signal processor and a novel digital control signal processor. This resulted in control circuit standardization and superior static and dynamic performance of the three dc-to-dc converters. Power components stress control, through active peak current limiting and recovery of switching losses, was applied to enhance reliability and converter efficiency.
Applying Padé via Lanczos to the finite element method for electromagnetic radiation problems
NASA Astrophysics Data System (ADS)
Slone, Rodney Daryl; Lee, Robert
2000-03-01
Recently there has been a great deal of interest in using the Padé via Lanczos (PVL) technique to analyze the transfer functions and impulse responses of large-scale linear circuits. In this paper, matrix-Padé via Lanczos (MPVL), which can be used on multiple-input multiple-output systems, is applied to solve models resulting from applying the finite element method (FEM) to electromagnetic wave propagation problems in the frequency domain. The resulting solution procedure of using MPVL to solve FEM equations allows for wideband frequency simulations with a reduction in total computation time. Several issues arise during this application, and each is addressed in detail. Numerical simulations using this method are shown along with traditional methods using an LU decomposition at each frequency point of interest. Comparisons in accuracy as well as computation time are also given.
An applied study using systems engineering methods to prioritize green systems options
Lee, Sonya M; Macdonald, John M
2009-01-01
For many years, there have been questions about the effectiveness of applying different green solutions. If you're building a home and wish to use green technologies, where do you start? While all technologies sound promising, which will perform the best over time? All this has to be considered within the cost and schedule of the project. The amount of information available on the topic can be overwhelming. We seek to examine if Systems Engineering methods can be used to help people choose and prioritize technologies that fit within their project and budget. Several methods are used to gain perspective into how to select the green technologies, such as the Analytic Hierarchy Process (AHP) and Kepner-Tregoe. In our study, subjects applied these methods to analyze cost, schedule, and trade-offs. Results will document whether the experimental approach is applicable to defining system priorities for green technologies.
Non-invasive imaging methods applied to neo- and paleontological cephalopod research
NASA Astrophysics Data System (ADS)
Hoffmann, R.; Schultz, J. A.; Schellhorn, R.; Rybacki, E.; Keupp, H.; Gerden, S. R.; Lemanis, R.; Zachow, S.
2013-11-01
Several non-invasive methods are common practice in natural sciences today. Here we present how they can be applied and contribute to current topics in cephalopod (paleo-) biology. Different methods will be compared in terms of time necessary to acquire the data, amount of data, accuracy/resolution, minimum-maximum size of objects that can be studied, of the degree of post-processing needed and availability. Main application of the methods is seen in morphometry and volumetry of cephalopod shells in order to improve our understanding of diversity and disparity, functional morphology and biology of extinct and extant cephalopods.
NASA Technical Reports Server (NTRS)
Miles, J. H.
1975-01-01
A computer method for obtaining a rational function representation of an acoustic spectrum and for correcting reflection effects is introduced. The functional representation provides a means of compact storage of data and the nucleus of the data analysis method. The method is applied to noise from a full-scale externally blown flap system with a quiet 6:1 bypass ratio turbofan engine and a three-flap wing section designed to simulate the take-off condition of a conceptual STOL aircraft.
Two methods of measuring muscle tone applied in patients with decerebrate rigidity.
Tsementzis, S A; Gillingham, F J; Gordon, A; Lakie, M D
1980-01-01
Two methods were used to measure muscle tone in patients with decerebrate rigidity. In the first method forces of square waveform were applied and the calculated compliance of the joint was used as an index of rigidity. Oscillatory transients were seen at the same frequency as the physiological tremor. The range of normal variation in compliance was large and the values measured in the patients flucuated markedly which limited the value of this index. In the second method, where forces of sinusoidal waveform were employed, the resonant frequency of the joint was measured and used as an index of rigidity. This index proved reliable and reproducible. PMID:7354353
Method of applying coatings to substrates and the novel coatings produced thereby
Hendricks, C.D.
1987-09-15
A method for applying novel coatings to substrates is provided. The ends of a multiplicity of rods of different materials are melted by focused beams of laser light. Individual electric fields are applied to each of the molten rod ends, thereby ejecting charged particles that include droplets, atomic clusters, molecules, and atoms. The charged particles are separately transported, by the accelerations provided by electric potentials produced by an electrode structure, to substrates where they combine and form the coatings. Layered and thickness graded coatings comprised of hitherto unavailable compositions, are provided. 2 figs.
Method of applying a cerium diffusion coating to a metallic alloy
Jablonski, Paul D.; Alman, David E.
2009-06-30
A method of applying a cerium diffusion coating to a preferred nickel base alloy substrate has been discovered. A cerium oxide paste containing a halide activator is applied to the polished substrate and then dried. The workpiece is heated in a non-oxidizing atmosphere to diffuse cerium into the substrate. After cooling, any remaining cerium oxide is removed. The resulting cerium diffusion coating on the nickel base substrate demonstrates improved resistance to oxidation. Cerium coated alloys are particularly useful as components in a solid oxide fuel cell (SOFC).
Construction of a dc-dc transformer - A model of transitory behavior under load
NASA Astrophysics Data System (ADS)
Louail, G.
A numerical model is presented for the construction of high performance dc-dc transformers for industrial applications, taking into account a variety of control techniques. Control logic to minimize fluctuations during load dumping intervals are defined. Problems linked to the demagnetization of the core are investigated and solutions are proposed. Attention is given to the selection of a commutator for a given application of a transformer, and functional characteristics of bipolar and MOS transistors are described. The principles are applied to the construction of a prototype second order transformer which is amenable to modular use. Finally, two methods of numerical modeling are presented: the first with simplified hypotheses for use with a hand calculator, and the second more rigourous, using discretized equations in a static regime. It is shown that a sudden power surge is the most critical phase for a power commutator. Progressively loading logic is devised, and the fabrication of 150 A commutators is indicated
NASA Astrophysics Data System (ADS)
Hadavand Mirzaei, Hossein; Hadi Meshkatalsadat, Mohammad; Soheilivand, Saeed
Chemical composition of the essential oil of the Prangos acaulis was extracted by Hydrodistillation (HD) and Supercritical Fluid Extraction (SFE) methods from aerial parts at full flowering stage. Their compositions were identified using GC/MS as the method of analysis. The analyses reveal that samples differ quantitatively and qualitatively. A total of 21 compounds constituting 89.1% of aerial parts oil were in SFE method. The oil obtained by SFE was under condition: pressure 120 bar, temperature 45°C and extraction time 45 min. On the other hand, 26 compounds constituting 98.74% of oil were in HD method. In according to our results, in both extracts, the two compounds present in the biggest quantity were: Α-pinene (13.7 versus 22.87% in the SFE and HD oil, respectively) and 3-ethylidene-2-methyl-1-hexen-4-yne (14.3 versus 21.36%).
Simultaneous distribution of AC and DC power
Polese, Luigi Gentile
2015-09-15
A system and method for the transport and distribution of both AC (alternating current) power and DC (direct current) power over wiring infrastructure normally used for distributing AC power only, for example, residential and/or commercial buildings' electrical wires is disclosed and taught. The system and method permits the combining of AC and DC power sources and the simultaneous distribution of the resulting power over the same wiring. At the utilization site a complementary device permits the separation of the DC power from the AC power and their reconstruction, for use in conventional AC-only and DC-only devices.
Marine organism repellent covering for protection of underwater objects and method of applying same
Fischer, K.J.
1993-07-13
A method is described of protecting the surface of underwater objects from fouling by growth of marine organisms thereon comprising the steps of: (A) applying a layer of waterproof adhesive to the surface to be protected; (B) applying to the waterproof adhesive layer, a deposit of cayenne pepper material; (C) applying a permeable layer of copper containing material to the adhesive layer in such a configuration as to leave certain areas of the outer surface of the adhesive layer exposed, through open portions of the permeable layer, to the ambient environment of the surface to be protected when such surface is submerged in water; (D) the permeable layer having the property of being a repellent to marine organisms.
Optimization methods of the net emission computation applied to cylindrical sodium vapor plasma
Hadj Salah, S. Hajji, S.; Ben Hamida, M. B.; Charrada, K.
2015-01-15
An optimization method based on a physical analysis of the temperature profile and different terms in the radiative transfer equation is developed to reduce the time computation of the net emission. This method has been applied for the cylindrical discharge in sodium vapor. Numerical results show a relative error of spectral flux density values lower than 5% with an exact solution, whereas the computation time is about 10 orders of magnitude less. This method is followed by a spectral method based on the rearrangement of the lines profile. Results are shown for Lorentzian profile and they demonstrated a relative error lower than 10% with the reference method and gain in computation time about 20 orders of magnitude.
Multigrid method applied to the solution of an elliptic, generalized eigenvalue problem
Alchalabi, R.M.; Turinsky, P.J.
1996-12-31
The work presented in this paper is concerned with the development of an efficient MG algorithm for the solution of an elliptic, generalized eigenvalue problem. The application is specifically applied to the multigroup neutron diffusion equation which is discretized by utilizing the Nodal Expansion Method (NEM). The underlying relaxation method is the Power Method, also known as the (Outer-Inner Method). The inner iterations are completed using Multi-color Line SOR, and the outer iterations are accelerated using Chebyshev Semi-iterative Method. Furthermore, the MG algorithm utilizes the consistent homogenization concept to construct the restriction operator, and a form function as a prolongation operator. The MG algorithm was integrated into the reactor neutronic analysis code NESTLE, and numerical results were obtained from solving production type benchmark problems.
NASA Astrophysics Data System (ADS)
Stewart, M. K.
2015-06-01
Understanding and modelling the relationship between rainfall and runoff has been a driving force in hydrology for many years. Baseflow separation and recession analysis have been two of the main tools for understanding runoff generation in catchments, but there are many different methods for each. The new baseflow separation method presented here (the bump and rise method or BRM) aims to accurately simulate the shape of tracer-determined baseflow or pre-event water. Application of the method by calibrating its parameters, using (a) tracer data or (b) an optimising method, is demonstrated for the Glendhu Catchment, New Zealand. The calibrated BRM algorithm is then applied to the Glendhu streamflow record. The new recession approach advances the thesis that recession analysis of streamflow alone gives misleading information on catchment storage reservoirs because streamflow is a varying mixture of components of very different origins and characteristics (at the simplest level, quickflow and baseflow as identified by the BRM method). Recession analyses of quickflow, baseflow and streamflow show that the steep power-law slopes often observed for streamflow at intermediate flows are artefacts due to mixing and are not representative of catchment reservoirs. Applying baseflow separation before recession analysis could therefore shed new light on water storage reservoirs in catchments and possibly resolve some current problems with recession analysis. Among other things it shows that both quickflow and baseflow reservoirs in the studied catchment have (non-linear) quadratic characteristics.
NASA Astrophysics Data System (ADS)
Langer, Stefan
2014-11-01
For unstructured finite volume methods an agglomeration multigrid with an implicit multistage Runge-Kutta method as a smoother is developed for solving the compressible Reynolds averaged Navier-Stokes (RANS) equations. The implicit Runge-Kutta method is interpreted as a preconditioned explicit Runge-Kutta method. The construction of the preconditioner is based on an approximate derivative. The linear systems are solved approximately with a symmetric Gauss-Seidel method. To significantly improve this solution method grid anisotropy is treated within the Gauss-Seidel iteration in such a way that the strong couplings in the linear system are resolved by tridiagonal systems constructed along these directions of strong coupling. The agglomeration strategy is adapted to this procedure by taking into account exactly these anisotropies in such a way that a directional coarsening is applied along these directions of strong coupling. Turbulence effects are included by a Spalart-Allmaras model, and the additional transport-type equation is approximately solved in a loosely coupled manner with the same method. For two-dimensional and three-dimensional numerical examples and a variety of differently generated meshes we show the wide range of applicability of the solution method. Finally, we exploit the GMRES method to determine approximate spectral information of the linearized RANS equations. This approximate spectral information is used to discuss and compare characteristics of multistage Runge-Kutta methods.
Applying Mathematical Optimization Methods to an ACT-R Instance-Based Learning Model
Said, Nadia; Engelhart, Michael; Kirches, Christian; Körkel, Stefan; Holt, Daniel V.
2016-01-01
Computational models of cognition provide an interface to connect advanced mathematical tools and methods to empirically supported theories of behavior in psychology, cognitive science, and neuroscience. In this article, we consider a computational model of instance-based learning, implemented in the ACT-R cognitive architecture. We propose an approach for obtaining mathematical reformulations of such cognitive models that improve their computational tractability. For the well-established Sugar Factory dynamic decision making task, we conduct a simulation study to analyze central model parameters. We show how mathematical optimization techniques can be applied to efficiently identify optimal parameter values with respect to different optimization goals. Beyond these methodological contributions, our analysis reveals the sensitivity of this particular task with respect to initial settings and yields new insights into how average human performance deviates from potential optimal performance. We conclude by discussing possible extensions of our approach as well as future steps towards applying more powerful derivative-based optimization methods. PMID:27387139
The Role of Applied Epidemiology Methods in the Disaster Management Cycle
Malilay, Josephine; Heumann, Michael; Perrotta, Dennis; Wolkin, Amy F.; Schnall, Amy H.; Podgornik, Michelle N.; Cruz, Miguel A.; Horney, Jennifer A.; Zane, David; Roisman, Rachel; Greenspan, Joel R.; Thoroughman, Doug; Anderson, Henry A.; Wells, Eden V.; Simms, Erin F.
2015-01-01
Disaster epidemiology (i.e., applied epidemiology in disaster settings) presents a source of reliable and actionable information for decision-makers and stakeholders in the disaster management cycle. However, epidemiological methods have yet to be routinely integrated into disaster response and fully communicated to response leaders. We present a framework consisting of rapid needs assessments, health surveillance, tracking and registries, and epidemiological investigations, including risk factor and health outcome studies and evaluation of interventions, which can be practiced throughout the cycle. Applying each method can result in actionable information for planners and decision-makers responsible for preparedness, response, and recovery. Disaster epidemiology, once integrated into the disaster management cycle, can provide the evidence base to inform and enhance response capability within the public health infrastructure. PMID:25211748
REMARKS ON THE MAXIMUM ENTROPY METHOD APPLIED TO FINITE TEMPERATURE LATTICE QCD.
UMEDA, T.; MATSUFURU, H.
2005-07-25
We make remarks on the Maximum Entropy Method (MEM) for studies of the spectral function of hadronic correlators in finite temperature lattice QCD. We discuss the virtues and subtlety of MEM in the cases that one does not have enough number of data points such as at finite temperature. Taking these points into account, we suggest several tests which one should examine to keep the reliability for the results, and also apply them using mock and lattice QCD data.
Applied Ecosystem Analysis - - a Primer : EDT the Ecosystem Diagnosis and Treatment Method.
Lestelle, Lawrence C.; Mobrand, Lars E.
1996-05-01
The aim of this document is to inform and instruct the reader about an approach to ecosystem management that is based upon salmon as an indicator species. It is intended to provide natural resource management professionals with the background information needed to answer questions about why and how to apply the approach. The methods and tools the authors describe are continually updated and refined, so this primer should be treated as a first iteration of a sequentially revised manual.
Campbell, Jeremy B; Newson, Steve
2013-02-26
Embodiments of DC source assemblies of power inverter systems of the type suitable for deployment in a vehicle having an electrically grounded chassis are provided. An embodiment of a DC source assembly comprises a housing, a DC source disposed within the housing, a first terminal, and a second terminal. The DC source also comprises a first capacitor having a first electrode electrically coupled to the housing, and a second electrode electrically coupled to the first terminal. The DC source assembly further comprises a second capacitor having a first electrode electrically coupled to the housing, and a second electrode electrically coupled to the second terminal.
Smart, JC
2016-01-01
Background The National HIV/AIDS Strategy calls for active surveillance programs for human immunodeficiency virus (HIV) to more accurately measure access to and retention in care across the HIV care continuum for persons living with HIV within their jurisdictions and to identify persons who may need public health services. However, traditional public health surveillance methods face substantial technological and privacy-related barriers to data sharing. Objective This study developed a novel data-sharing approach to improve the timeliness and quality of HIV surveillance data in three jurisdictions where persons may often travel across the borders of the District of Columbia, Maryland, and Virginia. Methods A deterministic algorithm of approximately 1000 lines was developed, including a person-matching system with Enhanced HIV/AIDS Reporting System (eHARS) variables. Person matching was defined in categories (from strongest to weakest): exact, very high, high, medium high, medium, medium low, low, and very low. The algorithm was verified using conventional component testing methods, manual code inspection, and comprehensive output file examination. Results were validated by jurisdictions using internal review processes. Results Of 161,343 uploaded eHARS records from District of Columbia (N=49,326), Maryland (N=66,200), and Virginia (N=45,817), a total of 21,472 persons were matched across jurisdictions over various strengths in a matching process totaling 21 minutes and 58 seconds in the privacy device, leaving 139,871 uniquely identified with only one jurisdiction. No records matched as medium low or low. Over 80% of the matches were identified as either exact or very high matches. Three separate validation methods were conducted for this study, and they all found ≥90% accuracy between records matched by this novel method and traditional matching methods. Conclusions This study illustrated a novel data-sharing approach that may facilitate timelier and better
NASA Astrophysics Data System (ADS)
Nobile, Lucio; Nobile, Stefano
This paper gives an overview of some recent advances of ultrasonic methods applied to materials and structures (including biological ones), exploring typical applications of these emerging inspection technologies to civil engineering and medicine. In confirmation of this trend, some results of an experimental research carried out involving both destructive and non-destructive testing methods for the evaluation of structural performance of existing reinforced concrete (RC) structures are discussed in terms of reliability. As a result, Ultrasonic testing can usefully supplement coring thus permitting less expensive and more representative evaluation of the concrete strength throughout the whole structure under examination.