Science.gov

Sample records for ac-ac matrix converter

  1. Operation Method for AC Motor Control during Power Interruption in Direct AC/AC Converter System

    NASA Astrophysics Data System (ADS)

    Shizu, Keiichiro; Azuma, Satoshi

    Direct AC/AC converters have been studied due to their potential use in power converters with no DC-link capacitor, which can contribute to the miniaturization of power converters. However, the absence of a DC-link capacitor makes it difficult to control the AC motor during power interruption. First, this paper proposes a system that realizes AC motor control during power interruption by utilizing a clamp capacitor. In general, direct AC/AC converters have a clamp circuit consisting of a rectifier diode(s) and a clamp capacitor in order to avoid over-voltages. In the proposed system, there is an additional semiconductor switch reverse-parallel to the rectifier diode(s), and the clamp capacitor voltage can be utilized for AC motor control by turning on the additional switch. Second, this paper discusses an operation method for AC motor control and clamp capacitor voltage control during power interruption. In the proposed method “DC-link voltage control”, the kinetic energy in the AC motor is transformed into electrical energy and stored in the clamp capacitor; the clamp capacitor is therefore charged and the capacitor voltage is controlled to remain constant at an instruction value. Third, this paper discusses a switching operation during power interruption. A dead-time is introduced between the operation of turning off all switches on the rectifier side and the operation of turning on the additional switch, which prevents the occurrence of a short circuit between the interrupted power source and the clamp capacitor. Finally, experimental results are presented. During power interruptions, an output current was continuously obtained and the clamp capacitor voltage was maintained to be equal to the instruction value of the capacitor voltage. These results indicate that both AC motor control and capacitor voltage control were successfully achieved by using the proposed system.

  2. Direct Space Vector PWM Strategy for Matrix Converters with Reduced Number of Switching Transitions

    NASA Astrophysics Data System (ADS)

    Tadano, Yugo; Hamada, Shizunori; Urushibata, Shota; Nomura, Masakatsu; Sato, Yukihiko; Ishida, Muneaki

    This paper proposes a novel “Direct Space Vector PWM (Direct SVPWM)” strategy based on the direct AC/AC conversion approach for three-phase to three-phase matrix converters. This method allows the sine input and sine output waveforms as a major premise, and gives top priority to the improvement of the output control performance in motor drive applications, for instance, provides maximum riding comfort for an elevator, etc. Output voltage harmonics, switching losses, and common-mode voltage can be reduced across the entire voltage region. In addition, the switching count can be reduced even further by fully utilizing the output current detection value. Direct space vectors are first defined, and the selection method of space vectors is described. Next, the PWM duty calculation technique is explained. Finally, the validity of the proposed method is proven from the comparison with the conventional virtual indirect method based on the experimental and analysis results.

  3. Boost matrix converters in clean energy systems

    NASA Astrophysics Data System (ADS)

    Karaman, Ekrem

    This dissertation describes an investigation of novel power electronic converters, based on the ultra-sparse matrix topology and characterized by the minimum number of semiconductor switches. The Z-source, Quasi Z-source, Series Z-source and Switched-inductor Z-source networks were originally proposed for boosting the output voltage of power electronic inverters. These ideas were extended here on three-phase to three-phase and three-phase to single-phase indirect matrix converters. For the three-phase to three-phase matrix converters, the Z-source networks are placed between the three-switch input rectifier stage and the output six-switch inverter stage. A brief shoot-through state produces the voltage boost. An optimal pulse width modulation technique was developed to achieve high boosting capability and minimum switching losses in the converter. For the three-phase to single-phase matrix converters, those networks are placed similarly. For control purposes, a new modulation technique has been developed. As an example application, the proposed converters constitute a viable alternative to the existing solutions in residential wind-energy systems, where a low-voltage variable-speed generator feeds power to the higher-voltage fixed-frequency grid. Comprehensive analytical derivations and simulation results were carried out to investigate the operation of the proposed converters. Performance of the proposed converters was then compared between each other as well as with conventional converters. The operation of the converters was experimentally validated using a laboratory prototype.

  4. High-frequency matrix converter with square wave input

    DOEpatents

    Carr, Joseph Alexander; Balda, Juan Carlos

    2015-03-31

    A device for producing an alternating current output voltage from a high-frequency, square-wave input voltage comprising, high-frequency, square-wave input a matrix converter and a control system. The matrix converter comprises a plurality of electrical switches. The high-frequency input and the matrix converter are electrically connected to each other. The control system is connected to each switch of the matrix converter. The control system is electrically connected to the input of the matrix converter. The control system is configured to operate each electrical switch of the matrix converter converting a high-frequency, square-wave input voltage across the first input port of the matrix converter and the second input port of the matrix converter to an alternating current output voltage at the output of the matrix converter.

  5. Novel Modulation Method for Multidirectional Matrix Converter

    PubMed Central

    Misron, Norhisam; Aris, Ishak Bin; Yamada, Hiroaki

    2014-01-01

    This study presents a new modulation method for multidirectional matrix converter (MDMC), based on the direct duty ratio pulse width modulation (DDPWM). In this study, a new structure of MDMC has been proposed to control the power flow direction through the stand-alone battery based system and hybrid vehicle. The modulation method acts based on the average voltage over one switching period concept. Therefore, in order to determine the duty ratio for each switch, the instantaneous input voltages are captured and compared with triangular waveform continuously. By selecting the proper switching pattern and changing the slope of the carriers, the sinusoidal input current can be synthesized with high power factor and desired output voltage. The proposed system increases the discharging time of the battery by injecting the power to the system from the generator and battery at the same time. Thus, it makes the battery life longer and saves more energy. This paper also derived necessary equation for proposed modulation method as well as detail of analysis and modulation algorithm. The theoretical and modulation concepts presented have been verified in MATLAB simulation. PMID:25298969

  6. Novel modulation method for multidirectional matrix converter.

    PubMed

    Toosi, Saman; Misron, Norhisam; Hanamoto, Tsuyoshi; Bin Aris, Ishak; Radzi, Mohd Amran Mohd; Yamada, Hiroaki

    2014-01-01

    This study presents a new modulation method for multidirectional matrix converter (MDMC), based on the direct duty ratio pulse width modulation (DDPWM). In this study, a new structure of MDMC has been proposed to control the power flow direction through the stand-alone battery based system and hybrid vehicle. The modulation method acts based on the average voltage over one switching period concept. Therefore, in order to determine the duty ratio for each switch, the instantaneous input voltages are captured and compared with triangular waveform continuously. By selecting the proper switching pattern and changing the slope of the carriers, the sinusoidal input current can be synthesized with high power factor and desired output voltage. The proposed system increases the discharging time of the battery by injecting the power to the system from the generator and battery at the same time. Thus, it makes the battery life longer and saves more energy. This paper also derived necessary equation for proposed modulation method as well as detail of analysis and modulation algorithm. The theoretical and modulation concepts presented have been verified in MATLAB simulation. PMID:25298969

  7. MatrixConverter: Facilitating construction of phenomic character matrices1

    PubMed Central

    Liu, Jing; Endara, Lorena; Burleigh, J. Gordon

    2015-01-01

    • Premise of the study: While numerous software packages enable scientists to evaluate molecular data and transform them for phylogenetic analyses, few such tools exist for phenomic data. We introduce MatrixConverter, a program that helps expedite and facilitate the transformation of raw phenomic character data into discrete character matrices that can be used in most evolutionary inference programs. • Methods and Results: MatrixConverter is an open source program written in Java; a platform-independent binary executable, as well as sample data sets and a user’s manual, are available at https://github.com/gburleigh/MatrixConverter/tree/master/distribution. MatrixConverter has a simple, intuitive user interface that enables the user to immediately begin scoring phenomic characters. We demonstrate the performance of MatrixConverter on a phenomic data set from cycads. • Conclusions: New technologies and software make it possible to obtain phenomic data from species across the tree of life, and MatrixConverter helps to transform these new data for evolutionary or ecological inference. PMID:25699217

  8. Systems and methods for deactivating a matrix converter

    DOEpatents

    Ransom, Ray M.

    2013-04-02

    Systems and methods are provided for deactivating a matrix conversion module. An electrical system comprises an alternating current (AC) interface, a matrix conversion module coupled to the AC interface, an inductive element coupled between the AC interface and the matrix conversion module, and a control module. The control module is coupled to the matrix conversion module, and in response to a shutdown condition, the control module is configured to operate the matrix conversion module to deactivate the first conversion module when a magnitude of a current through the inductive element is less than a threshold value.

  9. Preliminary Geologic Mapping of the Ac-S-3 Hemisphere of Ceres from NASA's Dawn Mission

    NASA Astrophysics Data System (ADS)

    Buczkowski, D. L.; Yingst, R. A.; Williams, D. A.; Scully, J. E. C.; Mest, S. C.; Crown, D. A.; Jaumann, R.; Russell, C. T.; Raymond, C. A.; Schenk, P. M.; Marchi, S.; O'Brien, D. P.; Nathues, A.; Hoffmann, M.; Schafer, M.; Platz, T.; Roatsch, T.; Kersten, E.; Preusker, F.; Stephan, K.

    2015-10-01

    NASA's Dawn spacecraft [1] was captured into orbit by the dwarf planet (1) Ceres on March 6, 2015. During the Approach phase capture was preceded and followed by a series of optical navigation and rotation characterization observations by Dawn's Framing Camera (FC) [2], which provided the first images of Ceres' surface. As was done at Vesta [3], the Dawn Science Team will conduct a geological mapping campaign at Ceres during the Nominal Mission, including iterative mapping using data obtained during each orbital phase. In this presentation we will describe the approach of the Ceres Mapping Campaign and discuss the preliminary geological mapping of the Ac-S-3 (180- 360˚E) hemisphere of Ceres.

  10. High voltage AC/AC electrochemical capacitor operating at low temperature in salt aqueous electrolyte

    NASA Astrophysics Data System (ADS)

    Abbas, Qamar; Béguin, François

    2016-06-01

    We demonstrate that an activated carbon (AC)-based electrochemical capacitor implementing aqueous lithium sulfate electrolyte in 7:3 vol:vol water/methanol mixture can operate down to -40 °C with good electrochemical performance. Three-electrode cell investigations show that the faradaic contributions related with hydrogen chemisorption in the negative AC electrode are thermodynamically unfavored at -40 °C, enabling the system to work as a typical electrical double-layer (EDL) capacitor. After prolonged floating of the AC/AC capacitor at 1.6 V and -40°C, the capacitance, equivalent series resistance and efficiency remain constant, demonstrating the absence of ageing related with side redox reactions at this temperature. Interestingly, when temperature is increased back to 24 °C, the redox behavior due to hydrogen storage reappears and the system behaves as a freshly prepared one.

  11. Method for Visualizing Switching Patterns for a Matrix Converter Using Instantaneous Space Vector Diagrams

    NASA Astrophysics Data System (ADS)

    Haruna, Junnosuke; Itoh, Jun-Ichi

    This paper discusses the characteristics of a matrix converter determined using instantaneous space vector diagrams. Since 27 switching patterns are available for the matrix converter, 27 types of output voltages and input currents can be obtained. The instantaneous output voltages and input currents are plotted on an instantaneous output voltage diagram and an input current diagram, respectively. Then, the switching patterns of the matrix converter are visualized. From the instantaneous space vector diagrams, the output voltage ripple and input current ripple can be determined on the basis of the vector selected from among 27 instantaneous output voltage/input current vectors. In addition, the instantaneous space vector diagrams can be used to analyze the switching times. In this study, six different of control methods for the matrix converter are evaluated by using instantaneous space vector diagrams and the total harmonic distortion of the output voltage and input current. The results lead to the conclusion that characteristics of the matrix converter can be effectively evaluated using the instantaneous space vector diagrams.

  12. Sustainable AC/AC hybrid electrochemical capacitors in aqueous electrolyte approaching the performance of organic systems

    NASA Astrophysics Data System (ADS)

    Abbas, Qamar; Babuchowska, Paulina; Frąckowiak, Elżbieta; Béguin, François

    2016-09-01

    A high energy hybrid AC/AC electrochemical capacitor has been realized in aqueous Li2SO4+KI electrolyte mixture. Owing to the redox processes associated with the 2I-/I2 system, the positive electrode operates in narrow potential range and displays high capacity. During prolonged potentiostatic floating at 1.6 V, the hybrid cell demonstrates remarkably stable capacitance and resistance. Analyses by temperature programmed desorption after floating at 1.6 V proved that oxidation of the positive AC electrode is prevented by the use of Li2SO4+KI, which enables the maximum potential of this electrode to be shifted below the water oxidation potential. When charged at 0.2 A g-1 up to U = 1.6 V, the hybrid cell displays a high capacitance of 75 F g-1 (300 F g-1 per mass of one electrode) compared to 47 F g-1 (188 F g-1 per mass of one electrode) for a symmetric cell in Li2SO4. At 0.2 A g-1 up to 1.6 V, the hybrid capacitor in Li2SO4+KI displays an energy density of 26 Wh kg-1 which approaches the energy density of 30.9 Wh kg-1 measured when the same carbon is implemented in a capacitor using TEABF4/ACN electrolyte and charged up to 2.5 V.

  13. Evidence on the Molecular Basis of the Ac/ac Adaptive Cyanogenesis Polymorphism in White Clover (Trifolium repens L.)

    PubMed Central

    Olsen, Kenneth M.; Hsu, Shih-Chung; Small, Linda L.

    2008-01-01

    White clover is polymorphic for cyanogenesis, with both cyanogenic and acyanogenic plants occurring in nature. This chemical defense polymorphism is one of the longest-studied and best-documented examples of an adaptive polymorphism in plants. It is controlled by two independently segregating genes: Ac/ac controls the presence/absence of cyanogenic glucosides; and Li/li controls the presence/absence of their hydrolyzing enzyme, linamarase. Whereas Li is well characterized at the molecular level, Ac has remained unidentified. Here we report evidence that Ac corresponds to a gene encoding a cytochrome P450 of the CYP79D protein subfamily (CYP79D15), and we describe the apparent molecular basis of the Ac/ac polymorphism. CYP79D orthologs catalyze the first step in cyanogenic glucoside biosynthesis in other cyanogenic plant species. In white clover, Southern hybridizations indicate that CYP79D15 occurs as a single-copy gene in cyanogenic plants but is absent from the genomes of ac plants. Gene-expression analyses by RT–PCR corroborate this finding. This apparent molecular basis of the Ac/ac polymorphism parallels our previous findings for the Li/li polymorphism, which also arises through the presence/absence of a single-copy gene. The nature of these polymorphisms may reflect white clover's evolutionary origin as an allotetraploid derived from cyanogenic and acyanogenic diploid progenitors. PMID:18458107

  14. Absorption and Attenuation Coefficients Using the WET Labs ac-s in the Mid-Atlantic Bight: Field Measurements and Data Analysis

    NASA Technical Reports Server (NTRS)

    Ohi, Nobuaki; Makinen, Carla P.; Mitchell, Richard; Moisan, Tiffany A.

    2008-01-01

    Ocean color algorithms are based on the parameterization of apparent optical properties as a function of inherent optical properties. WET Labs underwater absorption and attenuation meters (ac-9 and ac-s) measure both the spectral beam attenuation [c (lambda)] and absorption coefficient [a (lambda)]. The ac-s reports in a continuous range of 390-750 nm with a band pass of 4 nm, totaling approximately 83 distinct wavelengths, while the ac-9 reports at 9 wavelengths. We performed the ac-s field measurements at nine stations in the Mid-Atlantic Bight from water calibrations to data analysis. Onboard the ship, the ac-s was calibrated daily using Milli Q-water. Corrections for the in situ temperature and salinity effects on optical properties of water were applied. Corrections for incomplete recovery of the scattered light in the ac-s absorption tube were performed. The fine scale of spectral and vertical distributions of c (lambda) and a (lambda) were described from the ac-s. The significant relationships between a (674) and that of spectrophotometric analysis and chlorophyll a concentration of discrete water samples were observed.

  15. Study of switching transients in high frequency converters

    NASA Technical Reports Server (NTRS)

    Zinger, Donald S.; Elbuluk, Malik E.; Lee, Tony

    1993-01-01

    As the semiconductor technologies progress rapidly, the power densities and switching frequencies of many power devices are improved. With the existing technology, high frequency power systems become possible. Use of such a system is advantageous in many aspects. A high frequency ac source is used as the direct input to an ac/ac pulse-density-modulation (PDM) converter. This converter is a new concept which employs zero voltage switching techniques. However, the development of this converter is still in its infancy stage. There are problems associated with this converter such as a high on-voltage drop, switching transients, and zero-crossing detecting. Considering these problems, the switching speed and power handling capabilities of the MOS-Controlled Thyristor (MCT) makes the device the most promising candidate for this application. A complete insight of component considerations for building an ac/ac PDM converter for a high frequency power system is addressed. A power device review is first presented. The ac/ac PDM converter requires switches that can conduct bi-directional current and block bi-directional voltage. These bi-directional switches can be constructed using existing power devices. Different bi-directional switches for the converter are investigated. Detailed experimental studies of the characteristics of the MCT under hard switching and zero-voltage switching are also presented. One disadvantage of an ac/ac converter is that turn-on and turn-off of the switches has to be completed instantaneously when the ac source is at zero voltage. Otherwise shoot-through current or voltage spikes can occur which can be hazardous to the devices. In order for the devices to switch softly in the safe operating area even under non-ideal cases, a unique snubber circuit is used in each bi-directional switch. Detailed theory and experimental results for circuits using these snubbers are presented. A current regulated ac/ac PDM converter built using MCT's and IGBT's is

  16. Systems and methods for commutating inductor current using a matrix converter

    DOEpatents

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

    2012-10-16

    Systems and methods are provided for delivering current using a matrix converter in a vehicle. An electrical system comprises an AC interface, a first conversion module coupled to the AC interface, an inductive element coupled between the AC interface and the first conversion module, and a control module coupled to the first conversion module. The control module is configured to operate the first conversion module in a bidirectional operating mode to commutate current bidirectionally. When a magnitude of the current through the inductive element is greater than a first threshold value, the control module operates the conversion module in a unidirectional operating mode, wherein current is commutated unidirectionally.

  17. Novel Control for Voltage Boosted Matrix Converter based Wind Energy Conversion System with Practicality

    NASA Astrophysics Data System (ADS)

    Kumar, Vinod; Joshi, Raghuveer Raj; Yadav, Dinesh Kumar; Garg, Rahul Kumar

    2016-06-01

    This paper presents the implementation and investigation of novel voltage boosted matrix converter (MC) based permanent magnet wind energy conversion system (WECS). In this paper, on-line tuned adaptive fuzzy control algorithm cooperated with reversed MC is proposed to yield maximum energy. The control system is implemented on a dSPACE DS1104 real time board. Feasibility of the proposed system has been experimentally verified using a laboratory 1.2 kW prototype of WECS under steady-state and dynamic conditions.

  18. Three-phase ac-to-ac series-resonant power converter with a reduced number of thyristors

    SciTech Connect

    Klaassens, J.B.; de Beer, F. )

    1991-07-01

    This paper reports that ac-ac series-resonant converters have been proven to be functional and useful. Power pulse modulation with internal frequencies of tens of kHz and suited for multikilowatt power levels is applied to a series-resonant converter system for generating synthesized multiphase bipolar waveforms with reversible power flow and flow distortion. The use of a series-resonant circuit for power transfer and control obtains natural current commutation of the thyristors and the prevention of excessive stresses on components. Switches are required which have bidirectional current conduction and voltage blocking ability. The conventional series-resonant ac-ac converter applies a total for 24 anti-parallel thyristors. An alternative circuit configuration for the series-resonant ac-ac converter with only 12 thyristors is also presented. The alternative power circuit has three neutrals, related to the polyphase source, the load and the converter, which may be interconnected. If they are connected, the high-frequency component of the source and load currents will flow through the connection between the neutrals. The test results of a converter system generating three-phase sinusoidal input and output waveforms have demonstrated the significant aspects of this type of power interfaces.

  19. Angiotensin-converting enzyme and matrix metalloproteinase inhibition with developing heart failure: comparative effects on left ventricular function and geometry

    NASA Technical Reports Server (NTRS)

    McElmurray, J. H. 3rd; Mukherjee, R.; New, R. B.; Sampson, A. C.; King, M. K.; Hendrick, J. W.; Goldberg, A.; Peterson, T. J.; Hallak, H.; Zile, M. R.; Spinale, F. G.

    1999-01-01

    The progression of congestive heart failure (CHF) is left ventricular (LV) myocardial remodeling. The matrix metalloproteinases (MMPs) contribute to tissue remodeling and therefore MMP inhibition may serve as a useful therapeutic target in CHF. Angiotensin converting enzyme (ACE) inhibition favorably affects LV myocardial remodeling in CHF. This study examined the effects of specific MMP inhibition, ACE inhibition, and combined treatment on LV systolic and diastolic function in a model of CHF. Pigs were randomly assigned to five groups: 1) rapid atrial pacing (240 beats/min) for 3 weeks (n = 8); 2) ACE inhibition (fosinopril, 2.5 mg/kg b.i.d. orally) and rapid pacing (n = 8); 3) MMP inhibition (PD166793 2 mg/kg/day p.o.) and rapid pacing (n = 8); 4) combined ACE and MMP inhibition (2.5 mg/kg b.i.d. and 2 mg/kg/day, respectively) and rapid pacing (n = 8); and 5) controls (n = 9). LV peak wall stress increased by 2-fold with rapid pacing and was reduced in all treatment groups. LV fractional shortening fell by nearly 2-fold with rapid pacing and increased in all treatment groups. The circumferential fiber shortening-systolic stress relation was reduced with rapid pacing and increased in the ACE inhibition and combination groups. LV myocardial stiffness constant was unchanged in the rapid pacing group, increased nearly 2-fold in the MMP inhibition group, and was normalized in the ACE inhibition and combination treatment groups. Increased MMP activation contributes to the LV dilation and increased wall stress with pacing CHF and a contributory downstream mechanism of ACE inhibition is an effect on MMP activity.

  20. Mechanosensing and mechanochemical transduction: how is mechanical energy sensed and converted into chemical energy in an extracellular matrix?

    PubMed

    Silver, Frederick H; Siperko, Lorraine M

    2003-01-01

    Gravity plays a central role in vertebrate development and evolution. Gravitational forces acting on mammalian tissues cause the net muscle forces required for locomotion to be higher on earth than on a body subjected to a microgravitational field. As body mass increases during development, the musculoskeleton must be able to adapt by increasing the size of its functional units. Thus mechanical forces required to do the work (mechanical energy) of locomotion must be sensed by cells and converted into chemical energy (synthesis of new tissue). Extracellular matrices (ECMs) are multicomponent tissues that transduce internal and external mechanical signals into changes in tissue structure and function through a process termed mechanochemical transduction. Under the influence of an external gravitational field, both mineralized and unmineralized vertebrate tissues exhibit internal tensile forces that serve to preserve a synthetic phenotype in the resident cell population. Application of additional external forces alters the balance between the external gravitational force and internal forces acting on resident cells leading to changes in the expression of genes and production of protein that ultimately may alter the exact structure and function of the extracellular matrix. Changes in the equilibrium between internal and external forces acting on ECMs and changes in mechanochemical transduction processes at the cellular level appear to be important mechanisms by which mammals adjust their needs to store, transmit, and dissipate energy that is required during development and for bodily movements. Mechanosensing is postulated to involve many different cellular and extracellular components. Mechanical forces cause direct stretching of protein-cell surface integrin binding sites that occur on all eukaryotic cells. Stress-induced conformational changes in the extracellular matrix may alter integrin structure and lead to activation of several secondary messenger pathways

  1. SVPWM Technique with Varying DC-Link Voltage for Common Mode Voltage Reduction in a Matrix Converter and Analytical Estimation of its Output Voltage Distortion

    NASA Astrophysics Data System (ADS)

    Padhee, Varsha

    Common Mode Voltage (CMV) in any power converter has been the major contributor to premature motor failures, bearing deterioration, shaft voltage build up and electromagnetic interference. Intelligent control methods like Space Vector Pulse Width Modulation (SVPWM) techniques provide immense potential and flexibility to reduce CMV, thereby targeting all the afore mentioned problems. Other solutions like passive filters, shielded cables and EMI filters add to the volume and cost metrics of the entire system. Smart SVPWM techniques therefore, come with a very important advantage of being an economical solution. This thesis discusses a modified space vector technique applied to an Indirect Matrix Converter (IMC) which results in the reduction of common mode voltages and other advanced features. The conventional indirect space vector pulse-width modulation (SVPWM) method of controlling matrix converters involves the usage of two adjacent active vectors and one zero vector for both rectifying and inverting stages of the converter. By suitable selection of space vectors, the rectifying stage of the matrix converter can generate different levels of virtual DC-link voltage. This capability can be exploited for operation of the converter in different ranges of modulation indices for varying machine speeds. This results in lower common mode voltage and improves the harmonic spectrum of the output voltage, without increasing the number of switching transitions as compared to conventional modulation. To summarize it can be said that the responsibility of formulating output voltages with a particular magnitude and frequency has been transferred solely to the rectifying stage of the IMC. Estimation of degree of distortion in the three phase output voltage is another facet discussed in this thesis. An understanding of the SVPWM technique and the switching sequence of the space vectors in detail gives the potential to estimate the RMS value of the switched output voltage of any

  2. Thermionic energy converters

    DOEpatents

    Monroe, Jr., James E.

    1977-08-09

    A thermionic device for converting nuclear energy into electrical energy comprising a tubular anode spaced from and surrounding a cylindrical cathode, the cathode having an outer emitting surface of ruthenium, and nuclear fuel on the inner cylindrical surface. The nuclear fuel is a ceramic composition of fissionable material in a metal matrix. An axial void is provided to collect and contain fission product gases.

  3. XTL Converter

    SciTech Connect

    Spurgeon, Steven R

    2015-10-07

    "XTL Converter" is a short Python script for electron microscopy simulation. The program takes an input crystal file in the VESTA *.XTL format and converts it to a text format readable by the multislice simulation program ìSTEM. The process of converting a crystal *.XTL file to the format used by the ìSTEM simulation program is quite tedious; it generally requires the user to select dozens or hundreds of atoms, rearranging and reformatting their position. Header information must also be reformatted to a specific style to be read by ìSTEM. "XTL Converter" simplifies this process, saving the user time and allowing for easy batch processing of crystals.

  4. XTL Converter

    2015-10-07

    "XTL Converter" is a short Python script for electron microscopy simulation. The program takes an input crystal file in the VESTA *.XTL format and converts it to a text format readable by the multislice simulation program ìSTEM. The process of converting a crystal *.XTL file to the format used by the ìSTEM simulation program is quite tedious; it generally requires the user to select dozens or hundreds of atoms, rearranging and reformatting their position. Headermore » information must also be reformatted to a specific style to be read by ìSTEM. "XTL Converter" simplifies this process, saving the user time and allowing for easy batch processing of crystals.« less

  5. Thermionic converter

    DOEpatents

    Fitzpatrick, G.O.

    1987-05-19

    A thermionic converter is set forth which includes an envelope having an electron collector structure attached adjacent to a wall. An electron emitter structure is positioned adjacent the collector structure and spaced apart from opposite wall. The emitter and collector structures are in a common chamber. The emitter structure is heated substantially only by thermal radiation. Very small interelectrode gaps can be maintained utilizing the thermionic converter whereby increased efficiency results. 10 figs.

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

    DOEpatents

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

    2016-04-26

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

  7. Definition of peptide inhibitors from a synthetic peptide library by targeting gelatinase B/matrix metalloproteinase-9 (MMP-9) and TNF-α converting enzyme (TACE/ADAM-17).

    PubMed

    Qiu, Zheng; Yan, Ming; Li, Qian; Liu, Datao; Van den Steen, Philippe E; Wang, Min; Opdenakker, Ghislain; Hu, Jialiang

    2012-08-01

    Gelatinase B/matrix metalloproteinase-9 (MMP-9) is a regulatory and effector metalloproteinase in inflammation. TNF-α is an important proinflammatory cytokine and is released by the action of a Zn(2+)-containing converting enzyme (TACE/ADAM-17). Both metallo-enzymes play important roles during the development of shock syndromes. Combinatorial chemical synthesis and subsequent library deconvolution were previously used to define a peptide inhibitor (Regasepin1) acting, almost to the same degree, on neutrophil collagenase/MMP-8 and MMP-9 in vitro, and protecting mice against lethal endotoxinemia in vivo. We have now extended this approach by incorporating D-form amino acids and residues preferred by TACE. A new peptide library was designed and synthesized, and by deconvolution new peptide inhibitors were defined. These included a TACE-specific inhibitor, an MMP-9- specific inhibitor, and inhibitors for both enzymes.

  8. Thermionic converter

    DOEpatents

    Fitzpatrick, Gary O.

    1987-05-19

    A thermionic converter (10) is set forth which includes an envelope (12) having an electron collector structure (22) attached adjacent to a wall (16). An electron emitter structure (24) is positioned adjacent the collector structure (22) and spaced apart from opposite wall (14). The emitter (24) and collector (22) structures are in a common chamber (20). The emitter structure (24) is heated substantially only by thermal radiation. Very small interelectrode gaps (28) can be maintained utilizing the thermionic converter (10) whereby increased efficiency results.

  9. Data of the natural and pharmaceutical angiotensin-converting enzyme inhibitor isoleucine-tryptophan as a potent blocker of matrix metalloproteinase-2 expression in rat aorta.

    PubMed

    Kopaliani, Irakli; Martin, Melanie; Zatschler, Birgit; Müller, Bianca; Deussen, Andreas

    2016-09-01

    The present data are related to the research article entitled "Whey peptide isoleucine-tryptophan inhibits expression and activity of matrix metalloproteinase-2 in rat aorta" [1]. Here we present data on removal of endothelium from aorta, endothelium dependent aortic relaxation and inhibition of expression of pro-MMP2 by di-peptide isoleucine-tryptophan (IW). Experiments were performed in rat aortic endothelial cells (EC) and smooth muscle cells (SMC) in vitro, along with isolated rat aorta ex vivo. The cells and isolated aorta were stimulated with angiotensin II (ANGII) or angiotensin I (ANGI). ACE activity was inhibited by treatment with either IW or captopril (CA). Losartan was used as a blocker of angiotensin type-1 receptor. IW inhibited MMP2 protein expression induced with ANGI in a dose-dependent manner. IW was effective both in ECs and SMCs, as well as in isolated aorta. Similarly, captopril (CA) inhibited ANGI-induced MMP2 protein expression in both in vitro and ex vivo. Neither IW nor CA inhibited ANGII-induced MMP2 protein expression in contrast to losartan. The data also displays that removal of endothelium in isolated rat aorta abolished the endothelium-dependent relaxation induced with acetylcholine. However, SMC-dependent relaxation induced with sodium nitroprusside remained intact. Finally, the data provides histological evidence of selective removal of endothelial cells from aorta. PMID:27508250

  10. Convertible Stadium

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Air flotation technology used in NASA's Apollo program has found an interesting application in Hawaii's Aloha Stadium near Honolulu. The stadium's configuration can be changed, by moving entire 7,000-seat sections on a cushion of air, for best accommodation of spectators and participants at different types of events. In most stadiums, only a few hundred seats can be moved, by rolling sections on wheels or rails. At Aloha Stadium, 28,000 of the 50,000 seats can be repositioned for better spectator viewing and, additionally, for improved playing conditions. For example, a stadium designed primarily for football may compromise the baseball diamond by providing only a shallow outfield. Aloha's convertibility allows a full-size baseball field as well as optimum configurations for many other types of sports and special events. The photos show examples. The stadium owes its versatility to air flotation technology developed by General Motors. Its first large-scale application was movement of huge segments of the mammoth Saturn V moonbooster during assembly operations at Marshall Space Flight Center.

  11. Thermionic converter

    DOEpatents

    Rasor, Ned S.; Britt, Edward J.

    1976-01-01

    A gas-filled thermionic converter is provided with a collector and an emitter having a main emitter region and an auxiliary emitter region in electrical contact with the main emitter region. The main emitter region is so positioned with respect to the collector that a main gap is formed therebetween and the auxiliary emitter region is so positioned with respect to the collector that an auxiliary gap is formed therebetween partially separated from the main gap with access allowed between the gaps to allow ionizable gas in each gap to migrate therebetween. With heat applied to the emitter the work function of the auxiliary emitter region is sufficiently greater than the work function of the collector so that an ignited discharge occurs in the auxiliary gap and the work function of the main emitter region is so related to the work function of the collector that an unignited discharge occurs in the main gap sustained by the ions generated in the auxiliary gap. A current flows through a load coupled across the emitter and collector due to the unignited discharge in the main gap.

  12. Nanocrystal doped matrixes

    SciTech Connect

    Parce, J. Wallace; Bernatis, Paul; Dubrow, Robert; Freeman, William P.; Gamoras, Joel; Kan, Shihai; Meisel, Andreas; Qian, Baixin; Whiteford, Jeffery A.; Ziebarth, Jonathan

    2010-01-12

    Matrixes doped with semiconductor nanocrystals are provided. In certain embodiments, the semiconductor nanocrystals have a size and composition such that they absorb or emit light at particular wavelengths. The nanocrystals can comprise ligands that allow for mixing with various matrix materials, including polymers, such that a minimal portion of light is scattered by the matrixes. The matrixes of the present invention can also be utilized in refractive index matching applications. In other embodiments, semiconductor nanocrystals are embedded within matrixes to form a nanocrystal density gradient, thereby creating an effective refractive index gradient. The matrixes of the present invention can also be used as filters and antireflective coatings on optical devices and as down-converting layers. Processes for producing matrixes comprising semiconductor nanocrystals are also provided. Nanostructures having high quantum efficiency, small size, and/or a narrow size distribution are also described, as are methods of producing indium phosphide nanostructures and core-shell nanostructures with Group II-VI shells.

  13. Feasibility study for convertible engine torque converter

    NASA Technical Reports Server (NTRS)

    1985-01-01

    The feasibility study has shown that a dump/fill type torque converter has excellent potential for the convertible fan/shaft engine. The torque converter space requirement permits internal housing within the normal flow path of a turbofan engine at acceptable engine weight. The unit permits operating the engine in the turboshaft mode by decoupling the fan. To convert to turbofan mode, the torque converter overdrive capability bring the fan speed up to the power turbine speed to permit engagement of a mechanical lockup device when the shaft speed are synchronized. The conversion to turbofan mode can be made without drop of power turbine speed in less than 10 sec. Total thrust delivered to the aircraft by the proprotor, fan, and engine during tansient can be controlled to prevent loss of air speed or altitude. Heat rejection to the oil is low, and additional oil cooling capacity is not required. The turbofan engine aerodynamic design is basically uncompromised by convertibility and allows proper fan design for quiet and efficient cruise operation. Although the results of the feasibility study are exceedingly encouraging, it must be noted that they are based on extrapolation of limited existing data on torque converters. A component test program with three trial torque converter designs and concurrent computer modeling for fluid flow, stress, and dynamics, updated with test results from each unit, is recommended.

  14. Portable convertible blast effects shield

    DOEpatents

    Pastrnak, John W.; Hollaway, Rocky; Henning, Carl D.; Deteresa, Steve; Grundler, Walter; Hagler, Lisle B.; Kokko, Edwin; Switzer, Vernon A

    2007-05-22

    A rapidly deployable portable convertible blast effects shield/ballistic shield includes a set two or more telescoping cylindrical rings operably connected to each other to convert between a telescopically-collapsed configuration for storage and transport, and a telescopically-extended upright configuration forming an expanded inner volume. In a first embodiment, the upright configuration provides blast effects shielding, such as against blast pressures, shrapnel, and/or fire balls. And in a second embodiment, the upright configuration provides ballistic shielding, such as against incoming weapons fire, shrapnel, etc. Each ring has a high-strength material construction, such as a composite fiber and matrix material, capable of substantially inhibiting blast effects and impinging projectiles from passing through the shield. And the set of rings are releasably securable to each other in the telescopically-extended upright configuration, such as by click locks.

  15. Portable convertible blast effects shield

    DOEpatents

    Pastrnak, John W.; Hollaway, Rocky; Henning, Carl D.; Deteresa, Steve; Grundler, Walter; Hagler,; Lisle B.; Kokko, Edwin; Switzer, Vernon A

    2010-10-26

    A rapidly deployable portable convertible blast effects shield/ballistic shield includes a set two or more telescoping cylindrical rings operably connected to each other to convert between a telescopically-collapsed configuration for storage and transport, and a telescopically-extended upright configuration forming an expanded inner volume. In a first embodiment, the upright configuration provides blast effects shielding, such as against blast pressures, shrapnel, and/or fire balls. And in a second embodiment, the upright configuration provides ballistic shielding, such as against incoming weapons fire, shrapnel, etc. Each ring has a high-strength material construction, such as a composite fiber and matrix material, capable of substantially inhibiting blast effects and impinging projectiles from passing through the shield. And the set of rings are releasably securable to each other in the telescopically-extended upright configuration, such as by click locks.

  16. Portable convertible blast effects shield

    DOEpatents

    Pastrnak, John W.; Hollaway, Rocky; Henning, Carl D.; Deteresa, Steve; Grundler, Walter; Hagler, Lisle B.; Kokko, Edwin; Switzer, Vernon A.

    2011-03-15

    A rapidly deployable portable convertible blast effects shield/ballistic shield includes a set two or more frusto-conically-tapered telescoping rings operably connected to each other to convert between a telescopically-collapsed configuration for storage and transport, and a telescopically-extended upright configuration forming an expanded inner volume. In a first embodiment, the upright configuration provides blast effects shielding, such as against blast pressures, shrapnel, and/or fire balls. And in a second embodiment, the upright configuration provides ballistic shielding, such as against incoming weapons fire, shrapnel, etc. Each ring has a high-strength material construction, such as a composite fiber and matrix material, capable of substantially inhibiting blast effects and impinging projectiles from passing through the shield. And the set of rings are releasably securable to each other in the telescopically-extended upright configuration by the friction fit of adjacent pairs of frusto-conically-tapered rings to each other.

  17. Rotorcraft convertible engine study

    NASA Technical Reports Server (NTRS)

    Gill, J. C.; Earle, R. V.; Mar, H. M.

    1982-01-01

    The objective of the Rotorcraft Convertible Engine Study was to define future research and technology effort required for commercial development by 1988 of convertible fan/shaft gas turbine engines for unconventional rotorcraft transports. Two rotorcraft and their respective missions were defined: a Fold Tilt Rotor aircraft and an Advancing Blade Concept (ABC) rotorcraft. Sensitivity studies were conducted with these rotorcraft to determine parametrically the influence of propulsion characteristics on aircraft size, mission fuel requirements, and direct operating costs (DOC). The two rotorcraft were flown with conventional propulsion systems (separate lift/cruise engines) and with convertible propulsion systems to determine the benefits to be derived from convertible engines. Trade-off studies were conducted to determine the optimum engine cycle and staging arrangement for a convertible engine. Advanced technology options applicable to convertible engines were studied. Research and technology programs were identified which would ensure technology readiness for commercial development of convertible engines by 1988.

  18. ITER convertible blanket evaluation

    SciTech Connect

    Wong, C.P.C.; Cheng, E.

    1995-09-01

    Proposed International Thermonuclear Experimental Reactor (ITER) convertible blankets were reviewed. Key design difficulties were identified. A new particle filter concept is introduced and key performance parameters estimated. Results show that this particle filter concept can satisfy all of the convertible blanket design requirements except the generic issue of Be blanket lifetime. If the convertible blanket is an acceptable approach for ITER operation, this particle filter option should be a strong candidate.

  19. Interleaved power converter

    DOEpatents

    Zhu, Lizhi

    2007-11-13

    A power converter architecture interleaves full bridge converters to alleviate thermal management problems in high current applications, and may, for example, double the output power capability while reducing parts count and costs. For example, one phase of a three phase inverter is shared between two transformers, which provide power to a rectifier such as a current doubler rectifier to provide two full bridge DC/DC converters with three rather than four high voltage inverter legs.

  20. Cascaded resonant bridge converters

    NASA Technical Reports Server (NTRS)

    Stuart, Thomas A. (Inventor)

    1989-01-01

    A converter for converting a low voltage direct current power source to a higher voltage, high frequency alternating current output for use in an electrical system where it is desired to use low weight cables and other circuit elements. The converter has a first stage series resonant (Schwarz) converter which converts the direct current power source to an alternating current by means of switching elements that are operated by a variable frequency voltage regulator, a transformer to step up the voltage of the alternating current, and a rectifier bridge to convert the alternating current to a direct current first stage output. The converter further has a second stage series resonant (Schwarz) converter which is connected in series to the first stage converter to receive its direct current output and convert it to a second stage high frequency alternating current output by means of switching elements that are operated by a fixed frequency oscillator. The voltage of the second stage output is controlled at a relatively constant value by controlling the first stage output voltage, which is accomplished by controlling the frequency of the first stage variable frequency voltage controller in response to second stage voltage. Fault tolerance in the event of a load short circuit is provided by making the operation of the first stage variable frequency voltage controller responsive to first and second stage current limiting devices. The second stage output is connected to a rectifier bridge whose output is connected to the input of the second stage to provide good regulation of output voltage wave form at low system loads.

  1. Microminiature thermionic converters

    DOEpatents

    King, Donald B.; Sadwick, Laurence P.; Wernsman, Bernard R.

    2001-09-25

    Microminiature thermionic converts (MTCs) having high energy-conversion efficiencies and variable operating temperatures. Methods of manufacturing those converters using semiconductor integrated circuit fabrication and micromachine manufacturing techniques are also disclosed. The MTCs of the invention incorporate cathode to anode spacing of about 1 micron or less and use cathode and anode materials having work functions ranging from about 1 eV to about 3 eV. Existing prior art thermionic converter technology has energy conversion efficiencies ranging from 5-15%. The MTCs of the present invention have maximum efficiencies of just under 30%, and thousands of the devices can be fabricated at modest costs.

  2. Converting Nonclassicality into Entanglement.

    PubMed

    Killoran, N; Steinhoff, F E S; Plenio, M B

    2016-02-26

    Quantum mechanics exhibits a wide range of nonclassical features, of which entanglement in multipartite systems takes a central place. In several specific settings, it is well known that nonclassicality (e.g., squeezing, spin squeezing, coherence) can be converted into entanglement. In this work, we present a general framework, based on superposition, for structurally connecting and converting nonclassicality to entanglement. In addition to capturing the previously known results, this framework also allows us to uncover new entanglement convertibility theorems in two broad scenarios, one which is discrete and one which is continuous. In the discrete setting, the classical states can be any finite linearly independent set. For the continuous setting, the pertinent classical states are "symmetric coherent states," connected with symmetric representations of the group SU(K). These results generalize and link convertibility properties from the resource theory of coherence, spin coherent states, and optical coherent states, while also revealing important connections between local and nonlocal pictures of nonclassicality.

  3. Converting Nonclassicality into Entanglement.

    PubMed

    Killoran, N; Steinhoff, F E S; Plenio, M B

    2016-02-26

    Quantum mechanics exhibits a wide range of nonclassical features, of which entanglement in multipartite systems takes a central place. In several specific settings, it is well known that nonclassicality (e.g., squeezing, spin squeezing, coherence) can be converted into entanglement. In this work, we present a general framework, based on superposition, for structurally connecting and converting nonclassicality to entanglement. In addition to capturing the previously known results, this framework also allows us to uncover new entanglement convertibility theorems in two broad scenarios, one which is discrete and one which is continuous. In the discrete setting, the classical states can be any finite linearly independent set. For the continuous setting, the pertinent classical states are "symmetric coherent states," connected with symmetric representations of the group SU(K). These results generalize and link convertibility properties from the resource theory of coherence, spin coherent states, and optical coherent states, while also revealing important connections between local and nonlocal pictures of nonclassicality. PMID:26967398

  4. Digital scale converter

    DOEpatents

    Upton, Richard G.

    1978-01-01

    A digital scale converter is provided for binary coded decimal (BCD) conversion. The converter may be programmed to convert a BCD value of a first scale to the equivalent value of a second scale according to a known ratio. The value to be converted is loaded into a first BCD counter and counted down to zero while a second BCD counter registers counts from zero or an offset value depending upon the conversion. Programmable rate multipliers are used to generate pulses at selected rates to the counters for the proper conversion ratio. The value present in the second counter at the time the first counter is counted to the zero count is the equivalent value of the second scale. This value may be read out and displayed on a conventional seven-segment digital display.

  5. Vector generator scan converter

    DOEpatents

    Moore, J.M.; Leighton, J.F.

    1988-02-05

    High printing speeds for graphics data are achieved with a laser printer by transmitting compressed graphics data from a main processor over an I/O channel to a vector generator scan converter which reconstructs a full graphics image for input to the laser printer through a raster data input port. The vector generator scan converter includes a microprocessor with associated microcode memory containing a microcode instruction set, a working memory for storing compressed data, vector generator hardware for drawing a full graphic image from vector parameters calculated by the microprocessor, image buffer memory for storing the reconstructed graphics image and an output scanner for reading the graphics image data and inputting the data to the printer. The vector generator scan converter eliminates the bottleneck created by the I/O channel for transmitting graphics data from the main processor to the laser printer, and increases printer speed up to thirty fold. 7 figs.

  6. Vector generator scan converter

    DOEpatents

    Moore, James M.; Leighton, James F.

    1990-01-01

    High printing speeds for graphics data are achieved with a laser printer by transmitting compressed graphics data from a main processor over an I/O (input/output) channel to a vector generator scan converter which reconstructs a full graphics image for input to the laser printer through a raster data input port. The vector generator scan converter includes a microprocessor with associated microcode memory containing a microcode instruction set, a working memory for storing compressed data, vector generator hardward for drawing a full graphic image from vector parameters calculated by the microprocessor, image buffer memory for storing the reconstructed graphics image and an output scanner for reading the graphics image data and inputting the data to the printer. The vector generator scan converter eliminates the bottleneck created by the I/O channel for transmitting graphics data from the main processor to the laser printer, and increases printer speed up to thirty fold.

  7. Rotorcraft convertible engine study

    NASA Technical Reports Server (NTRS)

    Goldstein, D. N.; Hirschkron, R.; Smith, C. E.

    1983-01-01

    Convertible propulsion systems for advanced rotorcraft are evaluated in terms of their impact on aircraft operating economics and fuel consumption. A variety of propulsion system concepts, including separate thrust and power producing engines, convertible fan/shaft engines, and auxiliary propeller configurations are presented. The merits of each are evaluated in two different rotorcraft missions: an intercity, commercial transport of the ABC(TM) type, and an offshore oil ring supply ship of the X-wing type. The variable inlet guide vane fan/shaft converting engine and auxiliary propeller configurations are shown to offer significant advantages over all the other systems evaluated, in terms of both direct operating cost and fuel consumption.

  8. Vector generator scan converter

    SciTech Connect

    Moore, J.M.; Leighton, J.F.

    1990-04-17

    This patent describes high printing speeds for graphics data that are achieved with a laser printer by transmitting compressed graphics data from a main processor over an I/O (input/output) channel to a vector generator scan converter which reconstructs a full graphics image for input to the laser printer through a raster data input port. The vector generator scan converter includes a microprocessor with associated microcode memory containing a microcode instruction set, a working memory for storing compressed data, vector generator hardware for drawing a full graphic image from vector parameters calculated by the microprocessor, image buffer memory for storing the reconstructed graphics image and an output scanner for reading the graphics image data and inputting the data to the printer. The vector generator scan converter eliminates the bottleneck created by the I/O channel for transmitting graphics data from the main processor to the laser printer, and increases printer speed up to thirty fold.

  9. Fractional Watt AMTEC Converter

    NASA Astrophysics Data System (ADS)

    Hunt, T. K.; Rasmussen, J. R.

    2006-01-01

    We report here the long term performance of a small, multi-tube AMTEC converter. This converter was designed to operate and produce approximately 12 watt of electrical output from a small, 4 to 6 watt radioisotope heat source for remote power applications. It was built and put on test in 1999 using electrical heaters as stand-ins for the radioisotope capsule. Since that time it has accumulated more than 5 years of run time at an input heater temperature of 700 °C, with numerous thermal cycles to ambient that were generally related to grid power failures or physical moves of the test apparatus. The power output has remained, with variations due to orientation changes and minor variations due to small temperature changes, essentially constant at 0.40 W to 0.60 W over the test period and operation is ongoing. The converter casing and mechanical structure was fabricated from 316 SS and the electrodes are sputtered titanium nitride films. Separate static tests of a multilayer insulation package suitable for use with the converter showed the capability to reach 700 °C with a thermal input of < 4 watts.

  10. Liquid metal thermal electric converter

    DOEpatents

    Abbin, Joseph P.; Andraka, Charles E.; Lukens, Laurance L.; Moreno, James B.

    1989-01-01

    A liquid metal thermal electric converter which converts heat energy to electrical energy. The design of the liquid metal thermal electric converter incorporates a unique configuration which directs the metal fluid pressure to the outside of the tube which results in the structural loads in the tube to be compressive. A liquid metal thermal electric converter refluxing boiler with series connection of tubes and a multiple cell liquid metal thermal electric converter are also provided.

  11. Development of AC and DC Power Supply Direct Interface Converter

    NASA Astrophysics Data System (ADS)

    Kato, Koji; Itoh, Jun-Ichi

    This paper proposes a novel control method for a direct interface converter for management of the energy flow in either an AC or DC supply. The proposed converter is constructed based on an indirect matrix converter. Therefore a proposed control strategy is based on an indirect control method with a triangular carrier wave. The basic operation of the proposed control method is confirmed by experimental results. In addition, this paper also proposes a commutation error compensation method of an output voltage error and an input current error for an indirect matrix converter. In the proposed method, the output voltage and input current error by the commutation can be compensated at the same time, because the PWM pulse of each switch is directly compensated. The validity of the proposed method is confirmed by experimental results. Those results prove that the proposed compensation method can decrease total harmonic distortion (THD) of the input and output current.

  12. Digital to synchro converter

    NASA Technical Reports Server (NTRS)

    Predina, Joseph P. (Inventor)

    1989-01-01

    A digital-to-synchro converter is provided where a binary input code specifies a desired shaft angle and where an resolver type position transducer is employed with additional circuitry to generate a shaft position error signal indicative of the angular difference between the desired shaft angle and the actual shaft angle. The additional circuitry corrects for known and calculated errors in the shaft position detection process and equipment.

  13. Multilevel converters -- A new breed of power converters

    SciTech Connect

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

    1995-09-01

    Multilevel voltage source converters are emerging as a new breed of power converter options for high-power applications. The multilevel voltage source converters typically synthesize the staircase voltage wave from several levels of dc capacitor voltages. One of the major limitations of the multilevel converters is the voltage unbalance between different levels. The techniques to balance the voltage between different levels normally involve voltage clamping or capacitor charge control. There are several ways of implementing voltage balance in multilevel converters. Without considering the traditional magnetic coupled converters, this paper presents three recently developed multilevel voltage source converters: (1) diode-clamp, (2) flying-capacitors, and (3) cascaded-inverters with separate dc sources. The operating principle, features, constraints, and potential applications of these converters will be discussed.

  14. Transistorized converter provides nondissipative regulation

    NASA Technical Reports Server (NTRS)

    1964-01-01

    A transistorized regulator converter efficiently converts fluctuating input voltages to a constant output voltage, avoiding the use of saturable reactors. It is nondissipative in operation and functions in an open loop through variable duty cycles.

  15. Converting amine concentrations

    SciTech Connect

    Carroll, J.J. )

    1994-03-01

    Aqueous solutions of alkanolamines are commonly used solvents and remove acid gas components from natural and synthesis gas. The literature is full of experimental data for these systems and examples of their application. One problem with comparing data from different sources is that different concentration units are used. A BASIC program was written to simplify the conversion process between these common concentration units: weight fraction or mass fraction, X, kg solute/kg solution; mole fraction, x, mol solute/mol solution; molarity, M, mol solute/l solution; and molarity, m, mol solute/kg solvent. A table lists the formulas for converting between these four units. The source code is included.

  16. The microminiature thermionic converter

    NASA Astrophysics Data System (ADS)

    King, Donald Bryan

    The design, fabrication, testing, and analysis of the microminiature thermionic converter (MTC) is discussed. MTCs are two electrode devices that convert heat energy into electrical energy. The electrodes are spaced opposite each other in a vacuum environment with one electrode heated and the second cooled. Electrons are emitted from the hot electrode to the cool electrode creating electrical power. The fabrication of the MTC uses micromachining and semiconductor integrated circuit fabrication methods. These fabrication techniques allow the MTC to have an inter-electrode spacing of 20 microns or less with electrode materials having work functions ranging from 0.75 to 3 eV. The small gap size and low work function features of the MTC give it the potential to produce electricity at relatively high conversion efficiencies (20--25%). MTC designs may be tailored to function for different heat sources (combustion, solar, advanced nuclear reactors, radioisotopes, waste heat) over broad temperature regimes. The MTC diode prototype has been successfully fabricated, operated, and analyzed over a wide range of emitter and collector temperatures in the power production mode as well as power consumption mode. The emitter temperatures of interest ranged from 770 through 1220K. Maximum power output densities of 2mW/cm2 have been produced, and maximum output voltages approaching 1 Volt have also been produced. The MTC has been used to power an external load consisting of a Motorola 1N4004 diode. Models have been developed to characterize thermionic surface emission and electron transport across the gap. The MTC diode current-voltage characteristics and features have been successfully modeled over all five operational modes that characterize a thermionic converter. Power production has not been as high as expected. The shortcomings are due to the low work function material, (Ba,Sr,Ca)O, used in the diode. The tests and models indicate that the irregularities in work function across

  17. Cycloidal Wave Energy Converter

    SciTech Connect

    Stefan G. Siegel, Ph.D.

    2012-11-30

    This program allowed further advancing the development of a novel type of wave energy converter, a Cycloidal Wave Energy Converter or CycWEC. A CycWEC consists of one or more hydrofoils rotating around a central shaft, and operates fully submerged beneath the water surface. It operates under feedback control sensing the incoming waves, and converts wave power to shaft power directly without any intermediate power take off system. Previous research consisting of numerical simulations and two dimensional small 1:300 scale wave flume experiments had indicated wave cancellation efficiencies beyond 95%. The present work was centered on construction and testing of a 1:10 scale model and conducting two testing campaigns in a three dimensional wave basin. These experiments allowed for the first time for direct measurement of electrical power generated as well as the interaction of the CycWEC in a three dimensional environment. The Atargis team successfully conducted two testing campaigns at the Texas A&M Offshore Technology Research Center and was able to demonstrate electricity generation. In addition, three dimensional wave diffraction results show the ability to achieve wave focusing, thus increasing the amount of wave power that can be extracted beyond what was expected from earlier two dimensional investigations. Numerical results showed wave cancellation efficiencies for irregular waves to be on par with results for regular waves over a wide range of wave lengths. Using the results from previous simulations and experiments a full scale prototype was designed and its performance in a North Atlantic wave climate of average 30kW/m of wave crest was estimated. A full scale WEC with a blade span of 150m will deliver a design power of 5MW at an estimated levelized cost of energy (LCOE) in the range of 10-17 US cents per kWh. Based on the new results achieved in the 1:10 scale experiments these estimates appear conservative and the likely performance at full scale will

  18. Matrix superpotentials

    NASA Astrophysics Data System (ADS)

    Nikitin, Anatoly G.; Karadzhov, Yuri

    2011-07-01

    We present a collection of matrix-valued shape invariant potentials which give rise to new exactly solvable problems of SUSY quantum mechanics. It includes all irreducible matrix superpotentials of the generic form W=kQ+\\frac{1}{k} R+P, where k is a variable parameter, Q is the unit matrix multiplied by a real-valued function of independent variable x, and P and R are the Hermitian matrices depending on x. In particular, we recover the Pron'ko-Stroganov 'matrix Coulomb potential' and all known scalar shape invariant potentials of SUSY quantum mechanics. In addition, five new shape invariant potentials are presented. Three of them admit a dual shape invariance, i.e. the related Hamiltonians can be factorized using two non-equivalent superpotentials. We find discrete spectrum and eigenvectors for the corresponding Schrödinger equations and prove that these eigenvectors are normalizable.

  19. Gallium phosphide energy converters

    NASA Technical Reports Server (NTRS)

    Sims, P. E.; Dinetta, L. C.; Goetz, M. A.

    1995-01-01

    Gallium phosphide (GaP) energy converters may be successfully deployed to provide new mission capabilities for spacecraft. Betavoltaic power supplies based on the conversion of tritium beta decay to electricity using GaP energy converters can supply long term low-level power with high reliability. High temperature solar cells, also based on GaP, can be used in inward-bound missions greatly reducing the need for thermal dissipation. Results are presented for GaP direct conversion devices powered by Ni-63 and compared to the conversion of light emitted by tritiarated phosphors. Leakage currents as low as 1.2 x 10(exp -17) A/sq cm have been measured and the temperature dependence of the reverse saturation current is found to have ideal behavior. Temperature dependent IV, QE, R(sub sh), and V(sub oc) results are also presented. These data are used to predict the high-temperature solar cell and betacell performance of GaP devices and suggest appropriate applications for the deployment of this technology.

  20. Bidirectional buck boost converter

    DOEpatents

    Esser, Albert Andreas Maria

    1998-03-31

    A bidirectional buck boost converter and method of operating the same allows regulation of power flow between first and second voltage sources in which the voltage level at each source is subject to change and power flow is independent of relative voltage levels. In one embodiment, the converter is designed for hard switching while another embodiment implements soft switching of the switching devices. In both embodiments, first and second switching devices are serially coupled between a relatively positive terminal and a relatively negative terminal of a first voltage source with third and fourth switching devices serially coupled between a relatively positive terminal and a relatively negative terminal of a second voltage source. A free-wheeling diode is coupled, respectively, in parallel opposition with respective ones of the switching devices. An inductor is coupled between a junction of the first and second switching devices and a junction of the third and fourth switching devices. Gating pulses supplied by a gating circuit selectively enable operation of the switching devices for transferring power between the voltage sources. In the second embodiment, each switching device is shunted by a capacitor and the switching devices are operated when voltage across the device is substantially zero.

  1. Bidirectional buck boost converter

    DOEpatents

    Esser, A.A.M.

    1998-03-31

    A bidirectional buck boost converter and method of operating the same allows regulation of power flow between first and second voltage sources in which the voltage level at each source is subject to change and power flow is independent of relative voltage levels. In one embodiment, the converter is designed for hard switching while another embodiment implements soft switching of the switching devices. In both embodiments, first and second switching devices are serially coupled between a relatively positive terminal and a relatively negative terminal of a first voltage source with third and fourth switching devices serially coupled between a relatively positive terminal and a relatively negative terminal of a second voltage source. A free-wheeling diode is coupled, respectively, in parallel opposition with respective ones of the switching devices. An inductor is coupled between a junction of the first and second switching devices and a junction of the third and fourth switching devices. Gating pulses supplied by a gating circuit selectively enable operation of the switching devices for transferring power between the voltage sources. In the second embodiment, each switching device is shunted by a capacitor and the switching devices are operated when voltage across the device is substantially zero. 20 figs.

  2. Conversion of a Rhotrix to a "Coupled Matrix"

    ERIC Educational Resources Information Center

    Sani, B.

    2008-01-01

    In this note, a method of converting a rhotrix to a special form of matrix termed a "coupled matrix" is proposed. The special matrix can be used to solve various problems involving n x n and (n - 1) x (n - 1) matrices simultaneously.

  3. Electromagnetic wave energy converter

    NASA Technical Reports Server (NTRS)

    Bailey, R. L. (Inventor)

    1973-01-01

    Electromagnetic wave energy is converted into electric power with an array of mutually insulated electromagnetic wave absorber elements each responsive to an electric field component of the wave as it impinges thereon. Each element includes a portion tapered in the direction of wave propagation to provide a relatively wideband response spectrum. Each element includes an output for deriving a voltage replica of the electric field variations intercepted by it. Adjacent elements are positioned relative to each other so that an electric field subsists between adjacent elements in response to the impinging wave. The electric field results in a voltage difference between adjacent elements that is fed to a rectifier to derive dc output power.

  4. Unity power factor converter

    NASA Technical Reports Server (NTRS)

    Wester, Gene W. (Inventor)

    1980-01-01

    A unity power factor converter capable of effecting either inversion (dc-to-dc) or rectification (ac-to-dc), and capable of providing bilateral power control from a DC source (or load) through an AC transmission line to a DC load (or source) for power flow in either direction, is comprised of comparators for comparing the AC current i with an AC signal i.sub.ref (or its phase inversion) derived from the AC ports to generate control signals to operate a switch control circuit for high speed switching to shape the AC current waveform to a sine waveform, and synchronize it in phase and frequency with the AC voltage at the AC ports, by selectively switching the connections to a series inductor as required to increase or decrease the current i.

  5. Sync Matrix

    2004-12-31

    Sync Matrix provides a graphic display of the relationships among all of the response activities of each jurisdiction. This is accomplished through software that organizes and displays the activities by jurisdiction, function, and time for easy review and analysis. The software can also integrate the displays of multiple jurisdictions to allow examination of the total response.

  6. Turbo-Brayton Power Converter

    NASA Technical Reports Server (NTRS)

    Breedlove, Jeffrey

    2015-01-01

    Future NASA space missions will require advanced thermal-to-electric power converters that are reliable, efficient, and lightweight. Creare, LLC, is developing a turbo-Brayton power converter that offers high efficiency and specific power. The converter employs gas bearings to provide maintenance free, long-life operation. Discrete components can be packaged to fit optimally with other subsystems, and the converter's continuous gas flow can communicate directly with remote heat sources and heat rejection surfaces without the need for ancillary heat-transfer components and intermediate flow loops. Creare has completed detailed analyses, trade studies, fabrication trials, and preliminary designs for the components and converter assembly. The company is fabricating and testing a breadboard converter.

  7. Nanostructure Neutron Converter Layer Development

    NASA Technical Reports Server (NTRS)

    Park, Cheol (Inventor); Sauti, Godfrey (Inventor); Kang, Jin Ho (Inventor); Lowther, Sharon E. (Inventor); Thibeault, Sheila A. (Inventor); Bryant, Robert G. (Inventor)

    2016-01-01

    Methods for making a neutron converter layer are provided. The various embodiment methods enable the formation of a single layer neutron converter material. The single layer neutron converter material formed according to the various embodiments may have a high neutron absorption cross section, tailored resistivity providing a good electric field penetration with submicron particles, and a high secondary electron emission coefficient. In an embodiment method a neutron converter layer may be formed by sequential supercritical fluid metallization of a porous nanostructure aerogel or polyimide film. In another embodiment method a neutron converter layer may be formed by simultaneous supercritical fluid metallization of a porous nanostructure aerogel or polyimide film. In a further embodiment method a neutron converter layer may be formed by in-situ metalized aerogel nanostructure development.

  8. Self-powered microthermionic converter

    DOEpatents

    Marshall, Albert C.; King, Donald B.; Zavadil, Kevin R.; Kravitz, Stanley H.; Tigges, Chris P.; Vawter, Gregory A.

    2004-08-10

    A self-powered microthermionic converter having an internal thermal power source integrated into the microthermionic converter. These converters can have high energy-conversion efficiencies over a range of operating temperatures. Microengineering techniques are used to manufacture the converter. The utilization of an internal thermal power source increases potential for mobility and incorporation into small devices. High energy efficiency is obtained by utilization of micron-scale interelectrode gap spacing. Alpha-particle emitting radioisotopes can be used for the internal thermal power source, such as curium and polonium isotopes.

  9. Thyristor converter simulation and analysis

    SciTech Connect

    Zhang, S.Y.

    1991-01-01

    In this paper we present a simulation on thyristor converters. The simulation features nonlinearity, non-uniform firing, and the commutations. Several applications such as a current regulation, a converter frequency characteristics analysis, and a power line disturbance analysis will be presented. 4 refs., 4 figs.

  10. Proposed electromagnetic wave energy converter

    NASA Technical Reports Server (NTRS)

    Bailey, R. L.

    1973-01-01

    Device converts wave energy into electric power through array of insulated absorber elements responsive to field of impinging electromagnetic radiation. Device could also serve as solar energy converter that is potentially less expensive and fragile than solar cells, yet substantially more efficient.

  11. Architecture for a High-to-Medium-Voltage Power Converter

    NASA Technical Reports Server (NTRS)

    Vorpenian, Vatche

    2008-01-01

    A power converter now undergoing development is required to operate at a DC input potential ranging between 5.5 and 10 kV and a DC output potential of 400 V at a current up to 25 A. This power converter is also required to be sufficiently compact and reliable to fit and operate within the confines of a high-pressure case to be lowered to several miles (approx.5 km) below the surface of the ocean. The architecture chosen to satisfy these requirements calls for a series/ parallel arrangement of 48 high-frequency, pulse-width-modulation (PWM), transformer-isolation DC-to-DC power converter blocks. The input sides of the converter blocks would be connected in series so that the input potential would be divided among them, each of them being exposed to an input potential of no more than 10 kV/48 . 210 V. The series connection of inputs would also enforce a requirement that all the converter blocks operate at the same input current. The outputs of the converter blocks would be connected in a matrix comprising 6 parallel legs, each leg being a cascade of eight outputs wired in series (see figure). All the converter blocks would be identical within the tolerances of the values of their components. A single voltage feedback loop would regulate the output potential. All the converter blocks would be driven by the same PWM waveform generated by this feedback loop. The power transformer of each converter block would have a unity turns ratio and would be capable of withstanding as much as 10 kVDC between its primary and secondary windings. (Although, in general, the turns ratio could be different from unity, the simplest construction for minimizing leakage and maximizing breakdown voltage is attained at a turns ratio of unity.)

  12. Thermoionic converter for space Reactor

    NASA Astrophysics Data System (ADS)

    Cao, Shengquan; Yang, Jicai

    1990-05-01

    Thermionic converters offer many advantages for use as space reactors. Over the last several years, six experiments were performed, of which four were in-pile experiments and two out-pile experiments. Of the four in-pile experiments, three involved the use of three converters linked in series. The use of nuclear reactors as the power source for an electrical system in space is one of the important developmental projects under consideration today. For a time extending relatively long into the future, according to most opinions on potential power requirements, the choice of a thermionic converter to implement thermoelectric conversion has many advantages.

  13. Wind/water energy converter

    NASA Technical Reports Server (NTRS)

    Paulkovich, J.

    1979-01-01

    Device will convert wind, water, tidal or wave energy into electrical or mechanical energy. Is comprised of windmill-like paddles or blades synchronously geared to orient themselves to wind direction for optimum energy extraction.

  14. Transformerless dc-Isolated Converter

    NASA Technical Reports Server (NTRS)

    Rippel, Wally E.

    1987-01-01

    Efficient voltage converter employs capacitive instead of transformer coupling to provide dc isolation. Offers buck/boost operation, minimal filtering, and low parts count, with possible application in photovoltaic power inverters, power supplies and battery charges. In photovoltaic inverter circuit with transformerless converter, Q2, Q3, Q4, and Q5 form line-commutated inverter. Switching losses and stresses nil because switching performed when current is zero.

  15. Boron nitride converted carbon fiber

    DOEpatents

    Rousseas, Michael; Mickelson, William; Zettl, Alexander K.

    2016-04-05

    This disclosure provides systems, methods, and apparatus related to boron nitride converted carbon fiber. In one aspect, a method may include the operations of providing boron oxide and carbon fiber, heating the boron oxide to melt the boron oxide and heating the carbon fiber, mixing a nitrogen-containing gas with boron oxide vapor from molten boron oxide, and converting at least a portion of the carbon fiber to boron nitride.

  16. Radiation effects on DC-DC Converters

    NASA Technical Reports Server (NTRS)

    Zhang, Dexin; Attia, John O.; Kankam, Mark D. (Technical Monitor)

    2000-01-01

    DC-DC switching converters are circuits that can be used to convert a DC voltage of one value to another by switching action. They are increasing being used in space systems. Most of the popular DC-DC switching converters utilize power MOSFETs. However power MOSFETs, when subjected to radiation, are susceptible to degradation of device characteristics or catastrophic failure. This work focuses on the effects of total ionizing dose on converter performance. Four fundamental switching converters (buck converter, buck-boost converter, cuk converter, and flyback converter) were built using Harris IRF250 power MOSFETs. These converters were designed for converting an input of 60 volts to an output of about 12 volts with a switching frequency of 100 kHz. The four converters were irradiated with a Co-60 gamma source at dose rate of 217 rad/min. The performances of the four converters were examined during the exposure to the radiation. The experimental results show that the output voltage of the converters increases as total dose increases. However, the increases of the output voltage were different for the four different converters, with the buck converter and cuk converter the highest and the flyback converter the lowest. We observed significant increases in output voltage for cuk converter at a total dose of 24 krad (si).

  17. Expressions for parallel decomposition of the Mueller matrix.

    PubMed

    Sheppard, Colin J R; Castello, Marco; Diaspro, Alberto

    2016-04-01

    It is useful to convert between the Mueller matrix and two different Hermitian matrices, representing an optical material or system. We introduce forms for the matrices for transforming between the column vector forms of these different matrices. A review of matrix algebra is presented. We find that there is no great advantage, from the point of view of matrix manipulation, in using quantum mechanics ordering rather than the optical ordering of the Stokes parameters, as has been claimed elsewhere. PMID:27140786

  18. Expressions for parallel decomposition of the Mueller matrix.

    PubMed

    Sheppard, Colin J R; Castello, Marco; Diaspro, Alberto

    2016-04-01

    It is useful to convert between the Mueller matrix and two different Hermitian matrices, representing an optical material or system. We introduce forms for the matrices for transforming between the column vector forms of these different matrices. A review of matrix algebra is presented. We find that there is no great advantage, from the point of view of matrix manipulation, in using quantum mechanics ordering rather than the optical ordering of the Stokes parameters, as has been claimed elsewhere.

  19. High efficiency thermionic converter studies

    NASA Technical Reports Server (NTRS)

    Huffman, F. N.; Sommer, A. H.; Balestra, C. L.; Briere, T. R.; Lieb, D.; Oettinger, P. E.; Goodale, D. B.

    1977-01-01

    Research in thermionic energy conversion technology is reported. The objectives were to produce converters suitable for use in out of core space reactors, radioisotope generators, and solar satellites. The development of emitter electrodes that operate at low cesium pressure, stable low work function collector electrodes, and more efficient means of space charge neutralization were investigated to improve thermionic converter performance. Potential improvements in collector properties were noted with evaporated thin film barium oxide coatings. Experiments with cesium carbonate suggest this substance may provide optimum combinations of cesium and oxygen for thermionic conversion.

  20. Charge-pump voltage converter

    DOEpatents

    Brainard, John P.; Christenson, Todd R.

    2009-11-03

    A charge-pump voltage converter for converting a low voltage provided by a low-voltage source to a higher voltage. Charge is inductively generated on a transfer rotor electrode during its transit past an inductor stator electrode and subsequently transferred by the rotating rotor to a collector stator electrode for storage or use. Repetition of the charge transfer process leads to a build-up of voltage on a charge-receiving device. Connection of multiple charge-pump voltage converters in series can generate higher voltages, and connection of multiple charge-pump voltage converters in parallel can generate higher currents. Microelectromechanical (MEMS) embodiments of this invention provide a small and compact high-voltage (several hundred V) voltage source starting with a few-V initial voltage source. The microscale size of many embodiments of this invention make it ideally suited for MEMS- and other micro-applications where integration of the voltage or charge source in a small package is highly desirable.

  1. Converting Work into College Credits

    ERIC Educational Resources Information Center

    Hoffman, Joseph A.

    1976-01-01

    The Cooperative Education Program conducted by the New Jersey Department of Labor and Industry and Thomas A. Edison College enables State labor department employees to work toward college degrees by attending free classes, taking college-level examinations for college credit, and converting work and life experiences into college credits.…

  2. FM-to-Digital Converter

    NASA Technical Reports Server (NTRS)

    Moniuszko, Michael

    1987-01-01

    Circuit includes array of low-cost multivibrators. Inexpensive circuit converts frequency-modulated (FM) signal into digital signal. Consists of zero-crossing detector and series of monostable multivibrators and D-type flip-flops. Used to control filter.

  3. Multilevel converters for power system applications

    SciTech Connect

    Lai, J.S.; Stovall, J.P.; Peng, F.Z. |

    1995-09-01

    Multilevel converters are emerging as a new breed of power converter options for power system applications. These converters are most suitable for high voltage high power applications because they connect devices in series without the need for component matching. One of the major limitations of the multilevel converters is the voltage unbalance between different levels. To avoid voltage unbalance between different levels, several techniques have been proposed for different applications. Excluding magnetic-coupled converters, this paper introduces three multilevel voltage source converters: (1) diode-clamp, (2) flying-capacitors, and (3) cascaded inverters with separate dc sources. The operation principle, features, constraints, and potential applications of these converters will be discussed.

  4. Parametric study of laser photovoltaic energy converters

    NASA Technical Reports Server (NTRS)

    Walker, G. H.; Heinbockel, J. H.

    1987-01-01

    Photovoltaic converters are of interest for converting laser power to electrical power in a space-based laser power system. This paper describes a model for photovoltaic laser converters and the application of this model to a neodymium laser silicon photovoltaic converter system. A parametric study which defines the sensitivity of the photovoltaic parameters is described. An optimized silicon photovoltaic converter has an efficiency greater than 50 percent for 1000 W/sq cm of neodymium laser radiation.

  5. Transplantation: To convert or not to convert: lessons from the CONVERT trial.

    PubMed

    Bunnapradist, Suphamai; Vincenti, Flavio

    2009-07-01

    In participants of the CONVERT trial, which enrolled recipients of kidney transplants, conversion of immunosuppressive therapy from calcineurin inhibitors to sirolimus did not improve renal function. More importantly, the intervention was detrimental among patients with impaired kidney function and/or proteinuria. Sirolimus conversion resulted, however, in lower rates of malignancy.

  6. Hybrid matrix fiber composites

    DOEpatents

    Deteresa, Steven J.; Lyon, Richard E.; Groves, Scott E.

    2003-07-15

    Hybrid matrix fiber composites having enhanced compressive performance as well as enhanced stiffness, toughness and durability suitable for compression-critical applications. The methods for producing the fiber composites using matrix hybridization. The hybrid matrix fiber composites include two chemically or physically bonded matrix materials, whereas the first matrix materials are used to impregnate multi-filament fibers formed into ribbons and the second matrix material is placed around and between the fiber ribbons that are impregnated with the first matrix material and both matrix materials are cured and solidified.

  7. Multiphoton up-converting phosphors for use in rapid immunoassays

    NASA Astrophysics Data System (ADS)

    Niedbala, R. Sam; Vail, Timothy L.; Feindt, Hans; Li, S.; Burton, Jarrett L.

    2000-04-01

    There exists increasing demand for rapid in-vitro diagnostic test capable of detecting pathogens, disease markers, and drugs. Many currently marketed technologies are limiting due to their analytical sensitivity or the number of analytes detected in a single assay. Presented is the use of up- converting phosphors as reporters in rapid point-of-care diagnostic assays using a lateral flow format in a nitrocellulose matrix. Up-converting Phosphor Technology (UPT) utilizes lanthanide-doped ceramic particles that possess anti-Stokes shift emission. These material absorb multiple IR photons and emit dopant-dependent spectra in the visible range. Their signature spectra allow the development of sensitive, multi-analyte diagnostic test. Because no biological matrix up-converts in the IR, the sensitivity of the assay is enhanced, being determined by the affinity of the biological constituents and the level of non-specific binding of the particle reporter. Feasibility data presented below represent a wide range of molecular weight analytes, including drugs of abuse, proteins such as cardiac markers, and pathogenic microorganisms.

  8. Photoelectric converters with quantum coherence.

    PubMed

    Su, Shan-He; Sun, Chang-Pu; Li, Sheng-Wen; Chen, Jin-Can

    2016-05-01

    Photon impingement is capable of liberating electrons in electronic devices and driving the electron flux from the lower chemical potential to higher chemical potential. Previous studies hinted that the thermodynamic efficiency of a nanosized photoelectric converter at maximum power is bounded by the Curzon-Ahlborn efficiency η_{CA}. In this study, we apply quantum effects to design a photoelectric converter based on a three-level quantum dot (QD) interacting with fermionic baths and photons. We show that, by adopting a pair of suitable degenerate states, quantum coherences induced by the couplings of QDs to sunlight and fermion baths can coexist steadily in nanoelectronic systems. Our analysis indicates that the efficiency at maximum power is no longer limited to η_{CA} through manipulation of carefully controlled quantum coherences. PMID:27300826

  9. Photoelectric converters with quantum coherence

    NASA Astrophysics Data System (ADS)

    Su, Shan-He; Sun, Chang-Pu; Li, Sheng-Wen; Chen, Jin-Can

    2016-05-01

    Photon impingement is capable of liberating electrons in electronic devices and driving the electron flux from the lower chemical potential to higher chemical potential. Previous studies hinted that the thermodynamic efficiency of a nanosized photoelectric converter at maximum power is bounded by the Curzon-Ahlborn efficiency ηCA. In this study, we apply quantum effects to design a photoelectric converter based on a three-level quantum dot (QD) interacting with fermionic baths and photons. We show that, by adopting a pair of suitable degenerate states, quantum coherences induced by the couplings of QDs to sunlight and fermion baths can coexist steadily in nanoelectronic systems. Our analysis indicates that the efficiency at maximum power is no longer limited to ηCA through manipulation of carefully controlled quantum coherences.

  10. Photoelectric converters with quantum coherence.

    PubMed

    Su, Shan-He; Sun, Chang-Pu; Li, Sheng-Wen; Chen, Jin-Can

    2016-05-01

    Photon impingement is capable of liberating electrons in electronic devices and driving the electron flux from the lower chemical potential to higher chemical potential. Previous studies hinted that the thermodynamic efficiency of a nanosized photoelectric converter at maximum power is bounded by the Curzon-Ahlborn efficiency η_{CA}. In this study, we apply quantum effects to design a photoelectric converter based on a three-level quantum dot (QD) interacting with fermionic baths and photons. We show that, by adopting a pair of suitable degenerate states, quantum coherences induced by the couplings of QDs to sunlight and fermion baths can coexist steadily in nanoelectronic systems. Our analysis indicates that the efficiency at maximum power is no longer limited to η_{CA} through manipulation of carefully controlled quantum coherences.

  11. Status of advanced bremsstrahlung converters

    SciTech Connect

    Halbleib, J.A.

    1980-01-01

    This paper is an attempt to review the somewhat ill-defined area of advanced converter research in a more or less chronological fashion. Section 2 reviews the early B/sub z/ work that was motivated by the CASINO project. More recent work makes liberal use of technology from ICF research using REBs is discussed in Sec. 3. Section 4 discusses possible directions for future research, some of which are being actively pursued at Sandia National Laboratories (SNL) and elsewhere.

  12. High efficiency thermionic converter studies

    NASA Technical Reports Server (NTRS)

    Huffman, F. N.; Sommer, A. H.; Balestra, C. L.; Briere, D. P.; Oettinger, P. E.

    1976-01-01

    The objective is to improve thermionic converter performance by means of reduced interelectrode losses, greater emitter capabilities, and lower collector work functions until the converter performance level is suitable for out-of-core space reactors and radioisotope generators. Electrode screening experiments have identified several promising collector materials. Back emission work function measurements of a ZnO collector in a thermionic diode have given values less than 1.3 eV. Diode tests were conducted over the range of temperatures of interest for space power applications. Enhanced mode converter experiments have included triodes operated in both the surface ionization and plasmatron modes. Pulsed triodes were studied as a function of pulse length, pulse potential, inert gas fill pressure, cesium pressure, spacing, emitter temperature and collector temperature. Current amplifications (i.e., mean output current/mean grid current) of several hundred were observed up to output current densities of one amp/sq cm. These data correspond to an equivalent arc drop less than 0.1 eV.

  13. Current Sharing Analysis of Arm Prototype for ITER PF Converter Bridge

    NASA Astrophysics Data System (ADS)

    Li, Jinchao; Song, Zhiquan; Xu, Liuwei; Fu, Peng; Guo, Bin; Li, Sen; Dong, Lin; Wang, Min

    2014-03-01

    A bridge arm prototype of ITER poloidal field (PF) converter modules has been designed and fabricated. Non-cophase counter parallel connection is chosen as the arm structure of the prototype. Among all factors affecting current sharing, arm structure is the main one. During the design of the arm prototype, a novel method based on inductance matrixes is employed to improve the current sharing of the bridge arm. The test results on the prototype show that the current sharing performance of the arm prototype is much better than relevant design requirement, and that the matrix method is very effective to analyze and solve the current sharing problems of thyristor converters.

  14. Human Lung Angiotensin Converting Enzyme

    PubMed Central

    Friedland, Joan; Silverstein, Emanuel; Drooker, Martin; Setton, Charlotte

    1981-01-01

    To enable its immunohistologic localization, angiotensin converting enzyme (EC 3.4.15.1) from human lung was solubilized by trypsinization and purified ∼2,660-fold to apparent homogeneity from a washed lung particulate fraction. The specific activity of pure enzyme was estimated to be 117 μmol/min per mg protein with the substrate hippuryl-l-histidyl-l-leucine. Consistent with previously described lung enzyme studies, catalytic activity was strongly inhibited by EDTA, O-phenanthroline, SQ 20,881, and SQ 14,225 and increased by CoCl2. SQ 20,881 was a somewhat more potent inhibitor than SQ 14,225, unlike rabbit lung enzyme. The Michaelis constant (Km) with hippuryl-l-histidyl-l-leucine was 1.6 mM. The molecular weight was estimated at 150,000 from sucrose density gradient centrifugation. Sodium dodecyl sulfate polyacrylamide gel electrophoresis revealed a single polypeptide chain estimated at 130,000 daltons. Rabbit antibody to human lung enzyme was prepared by parenteral administration of pure angiotensin-converting enzyme in Freund's adjuvant. Rabbit antibody to human lung angiotensin-converting enzyme appeared to crossreact weakly with the rabbit enzyme and strongly inhibited the catalytic activity of the enzymes from human serum, lung, and lymph node. The specificity of the rabbit antibody and purity of the final human lung enzyme preparation was suggested by the single precipitin lines obtained by radial double immunodiffusion, and by the coincidence of enzyme catalytic activity and immunoreactivity on polyacrylamide gel electrophoresis, with both relatively pure and highly impure enzymes. Generally applicable sensitive analysis of acrylamide gels for immunoreactivity (and subsequently for any other activity) by use of intact gel slices in radial double immunodiffusion was devised. Human lung enzyme was very tightly bound to and catalytically active on anti-human enzyme antibody covalently bound to Sepharose 4B, and could not be readily dissociated without

  15. BASIC Matrix Operations.

    ERIC Educational Resources Information Center

    Digital Equipment Corp., Maynard, MA.

    The curriculum materials and computer programs in this booklet introduce the idea of a matrix. They go on to discuss matrix operations of addition, subtraction, multiplication by a scalar, and matrix multiplication. The last section covers several contemporary applications of matrix multiplication, including problems of communication…

  16. Discharging a DC bus capacitor of an electrical converter system

    DOEpatents

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

    2014-10-14

    A system and method of discharging a bus capacitor of a bidirectional matrix converter of a vehicle are presented here. The method begins by electrically shorting the AC interface of the converter after an AC energy source is disconnected from the AC interface. The method continues by arranging a plurality of switching elements of a second energy conversion module into a discharge configuration to establish an electrical current path from a first terminal of an isolation module, through an inductive element, and to a second terminal of the isolation module. The method also modulates a plurality of switching elements of a first energy conversion module, while maintaining the discharge configuration of the second energy conversion module, to at least partially discharge a DC bus capacitor.

  17. Large wind energy converter: Growian 3 MW

    NASA Technical Reports Server (NTRS)

    Koerber, F.; Thiele, H. A.

    1979-01-01

    The main features of the Growian wind energy converter are presented. Energy yield, environmental impact, and construction of the energy converter are discussed. Reliability of the windpowered system is assessed.

  18. Auxiliary resonant DC tank converter

    DOEpatents

    Peng, Fang Z.

    2000-01-01

    An auxiliary resonant dc tank (ARDCT) converter is provided for achieving soft-switching in a power converter. An ARDCT circuit is coupled directly across a dc bus to the inverter to generate a resonant dc bus voltage, including upper and lower resonant capacitors connected in series as a resonant leg, first and second dc tank capacitors connected in series as a tank leg, and an auxiliary resonant circuit comprising a series combination of a resonant inductor and a pair of auxiliary switching devices. The ARDCT circuit further includes first clamping means for holding the resonant dc bus voltage to the dc tank voltage of the tank leg, and second clamping means for clamping the resonant dc bus voltage to zero during a resonant period. The ARDCT circuit resonantly brings the dc bus voltage to zero in order to provide a zero-voltage switching opportunity for the inverter, then quickly rebounds the dc bus voltage back to the dc tank voltage after the inverter changes state. The auxiliary switching devices are turned on and off under zero-current conditions. The ARDCT circuit only absorbs ripples of the inverter dc bus current, thus having less current stress. In addition, since the ARDCT circuit is coupled in parallel with the dc power supply and the inverter for merely assisting soft-switching of the inverter without participating in real dc power transmission and power conversion, malfunction and failure of the tank circuit will not affect the functional operation of the inverter; thus a highly reliable converter system is expected.

  19. 12 CFR 1.6 - Convertible securities.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 1 2011-01-01 2011-01-01 false Convertible securities. 1.6 Section 1.6 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY INVESTMENT SECURITIES § 1.6 Convertible securities. A national bank may not purchase securities convertible into stock at the option...

  20. 12 CFR 1.6 - Convertible securities.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 1 2013-01-01 2013-01-01 false Convertible securities. 1.6 Section 1.6 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY INVESTMENT SECURITIES § 1.6 Convertible securities. A national bank may not purchase securities convertible into stock at the option...

  1. 12 CFR 1.6 - Convertible securities.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 1 2014-01-01 2014-01-01 false Convertible securities. 1.6 Section 1.6 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY INVESTMENT SECURITIES § 1.6 Convertible securities. A national bank may not purchase securities convertible into stock at the option...

  2. A matrix lower bound

    SciTech Connect

    Grcar, Joseph F.

    2002-02-04

    A matrix lower bound is defined that generalizes ideas apparently due to S. Banach and J. von Neumann. The matrix lower bound has a natural interpretation in functional analysis, and it satisfies many of the properties that von Neumann stated for it in a restricted case. Applications for the matrix lower bound are demonstrated in several areas. In linear algebra, the matrix lower bound of a full rank matrix equals the distance to the set of rank-deficient matrices. In numerical analysis, the ratio of the matrix norm to the matrix lower bound is a condition number for all consistent systems of linear equations. In optimization theory, the matrix lower bound suggests an identity for a class of min-max problems. In real analysis, a recursive construction that depends on the matrix lower bound shows that the level sets of continuously differential functions lie asymptotically near those of their tangents.

  3. A dc to dc converter

    NASA Astrophysics Data System (ADS)

    Willis, A. E.; Gould, J. M.; Matheney, J. L.; Garrett, H.

    1984-01-01

    The object of the invention is to provide an improved converter for converting one direct current voltage to another. A plurality of phased square wave voltages are provided from a ring counter through amplifiers to a like plurality of output transformers. Each of these transformers has two windings, and S(1) winding and an S(2) winding. The S(1) windings are connected in series, then the S(2) windings are connected in series, and finally, the two sets of windings are connected in series. One of six SCRs is connected between each two series connected windings to a positive output terminal and one of diodes is connected between each set of two windings of a zero output terminal. By virtue of this configuration, a quite high average direct current voltage is obtained, which varies between full voltage and two-thirds full voltage rather than from full voltage to zero. Further, its variation, ripple frequency, is reduced to one-sixth of that present in a single phase system. Application to raising battery voltage for an ion propulsion system is mentioned.

  4. Thermoelectric converters for alternating current standards

    NASA Astrophysics Data System (ADS)

    Anatychuk, L. I.; Taschuk, D. D.

    2012-06-01

    Thermoelectric converters of alternating current remain priority instruments when creating standard equipment. This work presents the results of design and manufacture of alternating current converter for a military standard of alternating current in Ukraine. Results of simulation of temperature distribution in converter elements, ways of optimization to improve the accuracy of alternating current signal reproduction are presented. Results of metrological trials are given. The quality of thermoelectric material specially created for alternating current metrology is verified. The converter was used in alternating current standard for the frequency range from 10 Hz to 30 MHz. The efficiency of using thermoelectric signal converters in measuring instruments is confirmed.

  5. UB Matrix Implementation for Inelastic Neutron Scattering Experiments

    SciTech Connect

    Lumsden, Mark D; Robertson, Lee; Yethiraj, Mohana

    2005-01-01

    The UB matrix approach has been extended to handle inelastic neutron scattering experiments with differing k{sub i} and k{sub f}. We have considered the typical goniometer employed on triple-axis and time-of-flight spectrometers. Expressions are derived to allow for calculation of the UB matrix and for converting from observables to Q-energy space. In addition, we have developed appropriate modes for calculation of angles for a specified Q-energy position.

  6. Microcomputer control of power converters

    SciTech Connect

    Alegria, C.M.; Freris, L.L.; Paiva, J.P.

    1984-08-01

    Thyristor power converters are charac terized by an inherent discrete control action and are, therefore, particularly well suited to on - line control by microcomputers. The paper presents a new design of digital controllers based upon powerful 16-bit or bit -slice microprocessors, which provide high firing time resolution and enough computing power to implement sophis ticated control strategies. Both hardware and software are discussed, with special emphasis on the firing con trol algorithms. The properties of Pulse Frequency Con trol (PFC) and Pulse Phase Control (PPC) are examined and small-signal discrete models are presented. These models are used in the analysis of constant current and constant extinction angle control through the z-transform method.

  7. Thermionic converter emitter support arrangement

    DOEpatents

    Allen, Daniel T.

    1990-01-01

    A support is provided for use in a therminonic converter to support an end of an emitter to keep it out of contact with a surrounding collector while allowing the emitter end to move axially as its temperature changes. The emitter end (34) is supported by a spring structure (44) that includes a pair of Belleville springs, and the spring structure is supported by a support structure (42) fixed to the housing that includes the collector. The support structure is in the form of a sandwich with a small metal spring-engaging element (74) at the front end, a larger metal main support (76) at the rear end that is attached to the housing, and with a ceramic layer (80) between them that is bonded by hot isostatic pressing to the metal element and metal main support. The spring structure can include a loose wafer (120) captured between the Belleville springs.

  8. Thermionic converter emitter support arrangement

    DOEpatents

    Allen, Daniel T.

    1990-01-01

    A support is provided for use in a thermionic converter to support an end an emitter to keep it out of contact with a surrounding collector while allowing the emitter end to move axially at its temperatures changes. The emitter end (34) is supported by a spring structure (44) that includes a pair of Belleville springs, and the spring structure is supported by a support structure (42) fixed to the housing that includes the collector. The support structure is in the form of a sandwich with a small metal spring-engaging element (74) at the front end, a larger metal main support (76) at the rear end that is attached to the housng, and with a ceramic layer (80) between them that is bonded by hot isostatic pressing to the metal element and metal main support. The spring structure can include a loose wafer (120) captured between the Belleville springs.

  9. Wood stove having catalytic converter

    SciTech Connect

    Willson, A.C.

    1982-12-14

    A wood burning stove is formed with double front and rear side walls of heat conductive metal spaced apart by heat conductive spacer fins and providing air passageways by which room air is heated by conduction from the walls which are heated by the burning of wood deposited on a firebox floor supported in heat conducting relationship with the inner side walls. A catalytic converter is disposed over the fire area in the upper portion of the stove, and is arranged to receive preheated fresh secondary air which mixes with hot, incompletely combusted compounds from the fire and, in the presence of the catalyst, induces a secondary combustion of the substances. This mixture is channeled into a heat extraction chamber where the secondary combustion is completed and the resultant heat is transferred to the metal body of the stove. An exhaust passageway is provided for releasing the products of complete combustion into the atmosphere.

  10. Thermionic converter emitter support arrangement

    NASA Astrophysics Data System (ADS)

    Allen, Daniel T.

    1989-07-01

    A support is discussed which was provided for use in a thermionic converter to support an end of an emitter to keep it out of contact with a surrounding collector while allowing the emitter end to move axially as its temperature changes. The emitter end is supported by a spring structure that includes a pair of Belleville springs, and the spring structure is supported by a support structure fixed to the housing that includes the collector. The support structure is in the form of a sandwich with a small metal spring-engaging element at the front end, a larger metal main support at the rear end that is attached to the housing, and with a ceramic layer between them that is bonded by hot isostatic pressing to the metal element and metal main support. The spring structure can include a loose wafer captured between the Belleville springs.

  11. Thermionic converter emitter support arrangement

    SciTech Connect

    Allen, D.T.

    1990-05-22

    This patent describes a support provided for use in a therminonic converter to support an end of an emitter to keep it out of contact with a surrounding collector while allowing the emitter end to move axially as its temperature changes. The emitter end is supported by a spring structure that includes a pair of Belleville springs, and the spring structure is supported by a support structure fixed to the housing that includes the collector. The support structure is in the form of a sandwich with a small metal spring-engaging element at the front end, a larger metal main support at the rear end that is attached to the housing, and with a ceramic layer between them that is bonded by hot isostatic pressing to the metal element and metal main support. The spring structure can include a loose wafer captured between the Belleville springs.

  12. Thermionic converter emitter support arrangement

    SciTech Connect

    Allen, D.T.

    1989-07-06

    This document discusses a support provided for use in a thermionic converter to support an end of an emitter to keep it out of contact with a surrounding collector while allowing the emitter end to move axially as its temperature changes. The emitter end is supported by a spring structure that includes a pair of Belleville springs, and the spring structure is supported by a support structure fixed to the housing that includes the collector. The support structure is in the form of a sandwich with a small metal spring-engaging element at the front end, a larger metal main support at the rear end that is attached to the housing, and with a ceramic layer between them that is bonded by hot isostatic pressing to the metal element and metal main support. The spring structure can include a loose wafer captured between the Belleville springs. 7 figs.

  13. Thermionic converter emitter support arrangement

    SciTech Connect

    Allen, D.T.

    1990-10-16

    A support is presented for use in a thermionic converted to support an end of an emitter to keep it out of contact with a surrounding collector while allowing the emitter end to move axially at its temperatures changes. The emitter end is supported by a spring structure that includes a pair of Belleville springs, and the spring structure is supported by a support structure fixed to the housing that includes the collector. The support structure is in the form of a sandwich with a small metal spring-engaging element at the front end, a large metal main support at the rear end that is attached to the housing, and metal main support. The spring structure can include a loose wafer captured between the Belleville springs.

  14. Sea water battery power converter

    NASA Astrophysics Data System (ADS)

    Hammond, Russell E.; Henry, John L.

    1991-04-01

    The invention converts the voltage output of a DC source to a higher voltage. A germanium transistor start-up circuit receives a DC supply voltage input and includes an astable multivibrator which produces a square wave voltage output that is transformed to a substantially DC steady-state voltage output by a transformer and a capacitor. This elevated voltage is provided to an oscillator circuit which provides two square wave outputs. Each output is provided to an array of invertors operably coupled to an array of field effect transistors. The transistors are operably coupled to a power transformer. The square wave outputs of the power transformer are full wave rectified to provide a DC output having a higher voltage than the system input voltage. The power transformer also provides another full wave rectified voltage which disables the start-up circuit to eliminate parasitic energy losses attributable to its continued oscillation.

  15. Carbonate fuel cell matrix

    DOEpatents

    Farooque, Mohammad; Yuh, Chao-Yi

    1996-01-01

    A carbonate fuel cell matrix comprising support particles and crack attenuator particles which are made platelet in shape to increase the resistance of the matrix to through cracking. Also disclosed is a matrix having porous crack attenuator particles and a matrix whose crack attenuator particles have a thermal coefficient of expansion which is significantly different from that of the support particles, and a method of making platelet-shaped crack attenuator particles.

  16. Carbonate fuel cell matrix

    DOEpatents

    Farooque, M.; Yuh, C.Y.

    1996-12-03

    A carbonate fuel cell matrix is described comprising support particles and crack attenuator particles which are made platelet in shape to increase the resistance of the matrix to through cracking. Also disclosed is a matrix having porous crack attenuator particles and a matrix whose crack attenuator particles have a thermal coefficient of expansion which is significantly different from that of the support particles, and a method of making platelet-shaped crack attenuator particles. 8 figs.

  17. Matrix differentiation formulas

    NASA Technical Reports Server (NTRS)

    Usikov, D. A.; Tkhabisimov, D. K.

    1983-01-01

    A compact differentiation technique (without using indexes) is developed for scalar functions that depend on complex matrix arguments which are combined by operations of complex conjugation, transposition, addition, multiplication, matrix inversion and taking the direct product. The differentiation apparatus is developed in order to simplify the solution of extremum problems of scalar functions of matrix arguments.

  18. Matrix with Prescribed Eigenvectors

    ERIC Educational Resources Information Center

    Ahmad, Faiz

    2011-01-01

    It is a routine matter for undergraduates to find eigenvalues and eigenvectors of a given matrix. But the converse problem of finding a matrix with prescribed eigenvalues and eigenvectors is rarely discussed in elementary texts on linear algebra. This problem is related to the "spectral" decomposition of a matrix and has important technical…

  19. Characterization and snubbing of a bidirectional MCT in a resonant ac link converter

    NASA Technical Reports Server (NTRS)

    Lee, Tony; Elbuluk, Malik E.; Zinger, Donald S.

    1993-01-01

    The MOS-Controlled Thyristor (MCT) is emerging as a powerful switch that combines the better characteristics of existing power devices. A study of switching stresses on an MCT switch under zero voltage resonant switching is presented. The MCT is used as a bidirectional switch in an ac/ac pulse density modulated inverter for induction motor drive. Current and voltage spikes are observed and analyzed with variations in the timing of the switching. Different snubber circuit configurations are under investigation to minimize the effect of these transients. The results will be extended to study and test the MCT switching in a medium power (5 hp) induction motor drive.

  20. 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).

  1. Performance of Power Converters at Cryogenic Temperatures

    NASA Technical Reports Server (NTRS)

    Elbuluk, Malik E.; Gerber, Scott; Hammoud, Ahmad; Patterson, Richard L.

    2001-01-01

    Power converters capable of operation at cryogenic temperatures are anticipated to play an important role in the power system architecture of future NASA deep space missions. Design of such converters to survive cryogenic temperatures will improve the power system performance and reduce development and launch costs. Aerospace power systems are mainly a DC distribution network. Therefore, DC/DC and DC/AC converters provide the outputs needed to different loads at various power levels. Recently, research efforts have been performed at the NASA Glenn Research Center (GRC) to design and evaluate DC/DC converters that are capable of operating at cryogenic temperatures. This paper presents a summary of the research performed to evaluate the low temperature performance of five DC/DC converters. Various parameters were investigated as a function of temperature in the range of 20 to -196 C. Data pertaining to the output voltage regulation and efficiency of the converters is presented and discussed.

  2. Simplified Heat-Source/Thermionic Converter

    NASA Technical Reports Server (NTRS)

    Shimada, K.

    1983-01-01

    Radiation coupling of heat from heat-source cylinder to converter cylinder through vacuum gap eliminates need for high-temperature electrical insulators between reactor heat pipes and thermionic converters. In addition no radiatior heat pipe is necessary because collectors of thermionic converters from which excess heat must be removed radiate directly to space. New design concept is also applicable to terrestrial and non-nuclear thermionic power supplies.

  3. Ocean floor mounting of wave energy converters

    DOEpatents

    Siegel, Stefan G

    2015-01-20

    A system for mounting a set of wave energy converters in the ocean includes a pole attached to a floor of an ocean and a slider mounted on the pole in a manner that permits the slider to move vertically along the pole and rotate about the pole. The wave energy converters can then be mounted on the slider to allow adjustment of the depth and orientation of the wave energy converters.

  4. 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.

  5. Vacuum-insulated catalytic converter

    DOEpatents

    Benson, David K.

    2001-01-01

    A catalytic converter has an inner canister that contains catalyst-coated substrates and an outer canister that encloses an annular, variable vacuum insulation chamber surrounding the inner canister. An annular tank containing phase-change material for heat storage and release is positioned in the variable vacuum insulation chamber a distance spaced part from the inner canister. A reversible hydrogen getter in the variable vacuum insulation chamber, preferably on a surface of the heat storage tank, releases hydrogen into the variable vacuum insulation chamber to conduct heat when the phase-change material is hot and absorbs the hydrogen to limit heat transfer to radiation when the phase-change material is cool. A porous zeolite trap in the inner canister absorbs and retains hydrocarbons from the exhaust gases when the catalyst-coated substrates and zeolite trap are cold and releases the hydrocarbons for reaction on the catalyst-coated substrate when the zeolite trap and catalyst-coated substrate get hot.

  6. SPARSKIT: A basic tool kit for sparse matrix computations

    NASA Technical Reports Server (NTRS)

    Saad, Youcef

    1990-01-01

    Presented here are the main features of a tool package for manipulating and working with sparse matrices. One of the goals of the package is to provide basic tools to facilitate the exchange of software and data between researchers in sparse matrix computations. The starting point is the Harwell/Boeing collection of matrices for which the authors provide a number of tools. Among other things, the package provides programs for converting data structures, printing simple statistics on a matrix, plotting a matrix profile, and performing linear algebra operations with sparse matrices.

  7. Modelling of HVDC converters for real-time transient simulators

    NASA Astrophysics Data System (ADS)

    Acevedo, Salvador

    This thesis presents developments in the computer modelling of High Voltage Direct Current (HVDC) converters and other FACTS devices for EMTP-type simulators. The high number and frequency of switching operations in power electronic converters cause numerical difficulties that require additional computational effort. The additional computational burden requires the development of techniques that can accelerate the simulation speeds of conventional electromagnetic transient modelling and may allow real-time simulations. The main results are two models that effectively reduce the computational time required to obtain the solution of an electrical network containing HVDC converters. Both approaches have in common the principle of subdividing an electrical circuit containing a 6n-valve converter into at least n subsystems. For each 6-valve subsystem, the 64 matrix combinations are precalculated and prestored in computer memory. The interaction between subsystems to obtain the network solution is particular to each approach. With this criterion, the number of precalculated combinations for a 24-valve HVDC substation is reduced from more than 16 million to only 256. Both models present a considerable reduction in the computational time required to simulate circuits containing HVDC converters. The most efficient model has been successfully implemented in the real time power systems simulator under development by the power research group at the University of British Columbia. The exact calculation of the network solution at switching events is another important aspect required to accurately simulate power electronic converters in power systems. The thesis proposes the zero crossing detection algorithm, which eliminates the erroneous delays present in traditional EMTP simulators. The proposed algorithm resynchronizes the solution to the original simulation time increment. To solve the problem originated by the forced commutation of Gate Turn Off Thyristors, an exploratory

  8. Catalytic converter with thermoelectric generator

    SciTech Connect

    Parise, R.J.

    1998-07-01

    The unique design of an electrically heated catalyst (EHC) and the inclusion of an ECO valve in the exhaust of an internal combustion engine will meet the strict new emission requirements, especially at vehicle cold start, adopted by several states in this country as well as in Europe and Japan. The catalytic converter (CC) has been a most useful tool in pollution abatement for the automobile. But the emission requirements are becoming more stringent and, along with other improvements, the CC must be improved to meet these new standards. Coupled with the ECO valve, the EHC can meet these new emission limits. In an internal combustion engine vehicle (ICEV), approximately 80% of the energy consumed leaves the vehicle as waste heat: out the tail pipe, through the radiator, or convected/radiated off the engine. Included with the waste heat out the tail pipe are the products of combustion which must meet strict emission requirements. The design of a new CC is presented here. This is an automobile CC that has the capability of producing electrical power and reducing the quantity of emissions at vehicle cold start, the Thermoelectric Catalytic Power Generator. The CC utilizes the energy of the exothermic reactions that take place in the catalysis substrate to produce electrical energy with a thermoelectric generator. On vehicle cold start, the thermoelectric generator is used as a heat pump to heat the catalyst substrate to reduce the time to catalyst light-off. Thus an electrically heated catalyst (EHC) will be used to augment the abatement of tail pipe emissions. Included with the EHC in the exhaust stream of the automobile is the ECO valve. This valve restricts the flow of pollutants out the tail pipe of the vehicle for a specified amount of time until the EHC comes up to operating temperature. Then the ECO valve opens and allows the full exhaust, now treated by the EHC, to leave the vehicle.

  9. Biofilm Matrix Proteins

    PubMed Central

    Fong, Jiunn N. C.; Yildiz, Fitnat H.

    2015-01-01

    Proteinaceous components of the biofilm matrix include secreted extracellular proteins, cell surface adhesins and protein subunits of cell appendages such as flagella and pili. Biofilm matrix proteins play diverse roles in biofilm formation and dissolution. They are involved in attaching cells to surfaces, stabilizing the biofilm matrix via interactions with exopolysaccharide and nucleic acid components, developing three-dimensional biofilm architectures, and dissolving biofilm matrix via enzymatic degradation of polysaccharides, proteins, and nucleic acids. In this chapter, we will review functions of matrix proteins in a selected set of microorganisms, studies of the matrix proteomes of Vibrio cholerae and Pseudomonas aeruginosa, and roles of outer membrane vesicles and of nucleoid-binding proteins in biofilm formation. PMID:26104709

  10. Power Converters Secure Electronics in Harsh Environments

    NASA Technical Reports Server (NTRS)

    2013-01-01

    In order to harden power converters for the rigors of space, NASA awarded multiple SBIR contracts to Blacksburg, Virginia-based VPT Inc. The resulting hybrid DC-DC converters have proven valuable in aerospace applications, and as a result the company has generated millions in revenue from the product line and created four high-tech jobs to handle production.

  11. Operation of high power converters in parallel

    NASA Technical Reports Server (NTRS)

    Decker, D. K.; Inouye, L. Y.

    1992-01-01

    Three different unequal power sharing approaches for parallel operation of converters - droop, master-slave, and proportional adjustment - are discussed. The approaches have been incorporated in the breadboard dc-dc converter units used in the space station power management and distribution dc test bed at the Lewis Research Center, where the system operation has been verified.

  12. 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.

  13. Distributed electrical leads for thermionic converter

    DOEpatents

    Fitzpatrick, Gary O.; Britt, Edward J.

    1979-01-01

    In a thermionic converter, means are provided for coupling an electrical lead to at least one of the electrodes thereof. The means include a bus bar and a plurality of distributed leads coupled to the bus bar each of which penetrates through one electrode and are then coupled to the other electrode of the converter in spaced apart relation.

  14. RF digital-to-analog converter

    DOEpatents

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

    1995-02-28

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

  15. Controller for a wave energy converter

    SciTech Connect

    Wilson, David G.; Bull, Diana L.; Robinett, III, Rush D.

    2015-09-22

    A wave energy converter (WEC) is described, the WEC including a power take off (PTO) that converts relative motion of bodies of the WEC into electrical energy. A controller controls operation of the PTO, causing the PTO to act as a motor to widen a wave frequency spectrum that is usable to generate electrical energy.

  16. Passive Resonant Bidirectional Converter with Galvanic Barrier

    NASA Technical Reports Server (NTRS)

    Rosenblad, Nathan S. (Inventor)

    2014-01-01

    A passive resonant bidirectional converter system that transports energy across a galvanic barrier includes a converter using at least first and second converter sections, each section including a pair of transfer terminals, a center tapped winding; a chopper circuit interconnected between the center tapped winding and one of the transfer terminals; an inductance feed winding interconnected between the other of the transfer terminals and the center tap and a resonant tank circuit including at least the inductance of the center tap winding and the parasitic capacitance of the chopper circuit for operating the converter section at resonance; the center tapped windings of the first and second converter sections being disposed on a first common winding core and the inductance feed windings of the first and second converter sections being disposed on a second common winding core for automatically synchronizing the resonant oscillation of the first and second converter sections and transferring energy between the converter sections until the voltage across the pairs of transfer terminals achieves the turns ratio of the center tapped windings.

  17. RF digital-to-analog converter

    DOEpatents

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

    1995-01-01

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

  18. Automatic switching matrix

    DOEpatents

    Schlecht, Martin F.; Kassakian, John G.; Caloggero, Anthony J.; Rhodes, Bruce; Otten, David; Rasmussen, Neil

    1982-01-01

    An automatic switching matrix that includes an apertured matrix board containing a matrix of wires that can be interconnected at each aperture. Each aperture has associated therewith a conductive pin which, when fully inserted into the associated aperture, effects electrical connection between the wires within that particular aperture. Means is provided for automatically inserting the pins in a determined pattern and for removing all the pins to permit other interconnecting patterns.

  19. Radiation Effects on DC-DC Converters

    NASA Technical Reports Server (NTRS)

    Zhang, De-Xin; AbdulMazid, M. D.; Attia, John O.; Kankam, Mark D. (Technical Monitor)

    2001-01-01

    In this work, several DC-DC converters were designed and built. The converters are Buck Buck-Boost, Cuk, Flyback, and full-bridge zero-voltage switched. The total ionizing dose radiation and single event effects on the converters were investigated. The experimental results for the TID effects tests show that the voltages of the Buck Buck-Boost, Cuk, and Flyback converters increase as total dose increased when using power MOSFET IRF250 as a switching transistor. The change in output voltage with total dose is highest for the Buck converter and the lowest for Flyback converter. The trend of increase in output voltages with total dose in the present work agrees with those of the literature. The trends of the experimental results also agree with those obtained from PSPICE simulation. For the full-bridge zero-voltage switch converter, it was observed that the dc-dc converter with IRF250 power MOSFET did not show a significant change of output voltage with total dose. In addition, for the dc-dc converter with FSF254R4 radiation-hardened power MOSFET, the output voltage did not change significantly with total dose. The experimental results were confirmed by PSPICE simulation that showed that FB-ZVS converter with IRF250 power MOSFET's was not affected with the increase in total ionizing dose. Single Event Effects (SEE) radiation tests were performed on FB-ZVS converters. It was observed that the FB-ZVS converter with the IRF250 power MOSFET, when the device was irradiated with Krypton ion with ion-energy of 150 MeV and LET of 41.3 MeV-square cm/mg, the output voltage increased with the increase in fluence. However, for Krypton with ion-energy of 600 MeV and LET of 33.65 MeV-square cm/mg, and two out of four transistors of the converter were permanently damaged. The dc-dc converter with FSF254R4 radiation hardened power MOSFET's did not show significant change at the output voltage with fluence while being irradiated by Krypton with ion energy of 1.20 GeV and LET of 25

  20. Mixed matrix membrane development.

    PubMed

    Kulprathipanja, Santi

    2003-03-01

    Two types of mixed matrix membranes were developed by UOP in the late 1980s. The first type includes adsorbent polymers, such as silicalite-cellulose acetate (CA), NaX-CA, and AgX-CA mixed matrix membranes. The silicalite-CA has a CO(2)/H(2) selectivity of 5.15 +/- 2.2. In contrast, the CA membrane has a CO(2)/H(2) selectivity of 0.77 +/- 0.06. The second type of mixed matrix membrane is PEG-silicone rubber. The PEG-silicone rubber mixed matrix membrane has high selectivity for polar gases, such as SO(2), NH(3), and H(2)S.

  1. Modelling, analyses and design of switching converters

    NASA Technical Reports Server (NTRS)

    Cuk, S. M.; Middlebrook, R. D.

    1978-01-01

    A state-space averaging method for modelling switching dc-to-dc converters for both continuous and discontinuous conduction mode is developed. In each case the starting point is the unified state-space representation, and the end result is a complete linear circuit model, for each conduction mode, which correctly represents all essential features, namely, the input, output, and transfer properties (static dc as well as dynamic ac small-signal). While the method is generally applicable to any switching converter, it is extensively illustrated for the three common power stages (buck, boost, and buck-boost). The results for these converters are then easily tabulated owing to the fixed equivalent circuit topology of their canonical circuit model. The insights that emerge from the general state-space modelling approach lead to the design of new converter topologies through the study of generic properties of the cascade connection of basic buck and boost converters.

  2. Polarization-controllable TE21 mode converter

    NASA Astrophysics Data System (ADS)

    Chang, T. H.; Yu, C. F.; Fan, C. T.

    2005-07-01

    We report the concept and development of a Ka-band mode and polarization converter that efficiently converts a TE10 rectangular waveguide mode into either a linearly or a circularly polarized TE21 cylindrical waveguide mode. The converter is composed of a power-dividing section, a mode-converting section, and a polarization-transitioning section. The converting process in each section is displayed and the working principles are discussed. A prototype has been built and tested. The measured results agree well with the numerical calculations for both linear and circular polarizations. The measured optimum back-to-back transmission is 94% with a 1-dB bandwidth of 4.1 GHz for the linear polarization. As for the circular polarization, the measured optimum transmission is 97%, but the corresponding bandwidth is indistinct due to some resonant dips. The reasons and impact for the dips are discussed. A bandwidth of 3.9 GHz is obtained for a single circular converter; meanwhile, an approach to eliminating these unwanted dips is presented in theory. For further diagnostics, the field pattern of either polarization is directly displayed on a temperature-sensitive liquid crystal display sheet, where the electric field strength can be discerned from the color spectrum. In addition to high conversion efficiency and broad bandwidth, this converter features easy construction, high mode purity, and polarization controllability.

  3. Grassmann matrix quantum mechanics

    DOE PAGES

    Anninos, Dionysios; Denef, Frederik; Monten, Ruben

    2016-04-21

    We explore quantum mechanical theories whose fundamental degrees of freedom are rectangular matrices with Grassmann valued matrix elements. We study particular models where the low energy sector can be described in terms of a bosonic Hermitian matrix quantum mechanics. We describe the classical curved phase space that emerges in the low energy sector. The phase space lives on a compact Kähler manifold parameterized by a complex matrix, of the type discovered some time ago by Berezin. The emergence of a semiclassical bosonic matrix quantum mechanics at low energies requires that the original Grassmann matrices be in the long rectangular limit.more » In conclusion, we discuss possible holographic interpretations of such matrix models which, by construction, are endowed with a finite dimensional Hilbert space.« less

  4. Programmable Analog-To-Digital Converter

    NASA Technical Reports Server (NTRS)

    Kist, Edward H., Jr.

    1993-01-01

    High-speed analog-to-digital converter with programmable voltage steps that can be changed during operation. Allows concentration of converter resolution over specific portion of waveform. Particularly useful in digitizing wind-shear radar and lidar return signals, in digital oscilloscopes, and other applications in which desirable to increase digital resolution over specific area of waveform while accepting lower resolution over rest of waveform. Effective increase in dynamic range achieved without increase in number of analog-to-digital converter bits. Enabling faster analog-to-digital conversion.

  5. Operation of high power converters in parallel

    NASA Technical Reports Server (NTRS)

    Decker, D. K.; Inouye, L. Y.

    1993-01-01

    High power converters that are used in space power subsystems are limited in power handling capability due to component and thermal limitations. For applications, such as Space Station Freedom, where multi-kilowatts of power must be delivered to user loads, parallel operation of converters becomes an attractive option when considering overall power subsystem topologies. TRW developed three different unequal power sharing approaches for parallel operation of converters. These approaches, known as droop, master-slave, and proportional adjustment, are discussed and test results are presented.

  6. Semiconductor Thermoelectric Converters of Alternating Current Signals

    NASA Astrophysics Data System (ADS)

    Anatychuk, L. I.; Bodnaruk, V. I.; Taschuk, D. D.

    2011-05-01

    Measuring converters have been developed based on Bi2Te3 solid solutions optimized for temperature and temporal stability of the basic thermoelectric parameters (thermal conductivity, electrical conductivity, and the Seebeck coefficient). Semiconductor material was grown by the vertical zone melting method. High efficiency of the optimized semiconductor materials made it possible to reduce the operating temperature considerably, as well as facilitating selection of structural materials and the converter fabrication technique. The influence of the Peltier and Thomson effects on the accuracy of direct current conversion has been reduced, and the operating frequency range of measurements has been expanded. Thermoelectric converters with sensitivity up to 30 V W-1 have been created without evacuation of the working space, which is filled with an inert gas mixture. The engineered converters offer the advantages of high sensitivity and a wide operating frequency range (up to 30 MHz).

  7. Photonic-to-plasmonic mode converter.

    PubMed

    Melikyan, Argishti; Kohl, Manfred; Sommer, Martin; Koos, Christian; Freude, Wolfgang; Leuthold, Juerg

    2014-06-15

    A novel photonic-to-plasmonic mode converter for efficiently converting a silicon strip waveguide mode to a gap surface plasmon polariton (SPP) of a metallic slot structure is proposed. A conversion efficiency of more than 85% is found for metallic slots with a slot size of 30-50 nm. Calculations show that high conversion efficiencies can be achieved for various cladding materials with refractive indices of 1.44, 1.6, and 1.7. The optical 1 dB bandwidth of the converter is around 200 nm. The proposed mode converter shows a good tolerance with respect to fabrication errors, and it requires a simple fabrication procedure only.

  8. Waveguide mode converter and method using same

    DOEpatents

    Moeller, Charles P.

    1990-01-01

    A waveguide mode converter converts electromagnetic power being transmitted in a TE.sub.0n or a TM.sub.0n mode, where n is an integer, to an HE.sub.11 mode. The conversion process occurs in a single stage without requiring the power to pass through any intermediate modes. The converter comprises a length of circular corrugated waveguide formed in a multiperiod periodic curve. The period of the curve is selected to couple the desired modes and decouple undesired modes. The corrugation depth is selected to control the phase propagation constant, or wavenumbers, of the input and output modes, thereby preventing coherent coupling to competing modes. In one embodiment, both the period and amplitude of the curve may be selectively adjusted, thereby allowing the converter to be tuned to maximize the conversion efficiency.

  9. Rotorcraft convertible engines for the 1980s

    NASA Technical Reports Server (NTRS)

    Eisenberg, J. D.

    1982-01-01

    Two rotorcraft studies were executed. The goal was to identify attractive techniques for implementing convertible powerplants for the ABC, Folded Tilt Rotor, and X-wing type high speed, high-L/D rotorcraft; to determine the DOC and fuel savings benefits achieved thereby; and to define research required to bring these powerplants into existence by the 1990's. These studies are reviewed herein and the different methods of approach are pointed out as well as the key findings. Fan shaft engines using variable inlet guide vanes or torque converters, and turboprop powerplants appear attractive. Savings in DOC and fuel consumption of over 15 percent are predicted in some cases as a result of convertible engine use rather than using separate engines for the thrust and the shaft functions. Areas of required research are fan performance (including noise), integrated engine/rotorcraft control, torque converters, turbine design, airflow for rotorcraft torque control, bleed for lift flow, and transmissions and clutches.

  10. Converting Garbage to Gold: Recycling Our Materials.

    ERIC Educational Resources Information Center

    Chandler, William U.

    1984-01-01

    Recycling conserves energy, fights pollution and inflation, creates jobs, and improves the outlook for the future of materials. But converting a throwaway society to recycling will depend on finding good markets for waste paper and scrap metals. (RM)

  11. Purification of prosomatostatin-converting enzymes.

    PubMed

    Mackin, R B; Noe, B D; Spiess, J

    1990-09-01

    The enzymes responsible for performing cleavage of propeptides at basic amino acids have proven difficult to characterize. Using the processing of anglerfish islet prosomatostatin (PSS) as a model system, we are pursuing the characterization of both a single basic amino acid-specific and a dibasic amino acid-specific converting enzyme. We describe here the model system and protein isolation methods that have allowed significant progress toward complete characterization of the somatostatin-generating propeptide converting enzymes (PCEs). PMID:1976216

  12. ANALOG-TO-DIGITAL DATA CONVERTER

    DOEpatents

    Rodgers, G.W.; Althouse, J.E.; Anderson, D.P.; Bussey, G.R.; Minnear, L.H.

    1960-09-01

    Electrical apparatus is described, particularly useful in telemetry work, for converting analog signals into electrical pulses and recording them. An electronic editor commands the taking of signal readings at a frequency which varies according to linearity of the analog signal being converted. Readings of information signals are recorded, along with time base readings and serial numbering, if desired, on magnetic tape and the latter may be used to operate a computer or the like. Magnetic tape data may be transferred to punched cards.

  13. Hybrid matrix amplifier

    DOEpatents

    Martens, J.S.; Hietala, V.M.; Plut, T.A.

    1995-01-03

    The present invention comprises a novel matrix amplifier. The matrix amplifier includes an active superconducting power divider (ASPD) having N output ports; N distributed amplifiers each operatively connected to one of the N output ports of the ASPD; and a power combiner having N input ports each operatively connected to one of the N distributed amplifiers. The distributed amplifier can included M stages of amplification by cascading superconducting active devices. The power combiner can include N active elements. The resulting (N[times]M) matrix amplifier can produce signals of high output power, large bandwidth, and low noise. 6 figures.

  14. Hybrid matrix amplifier

    DOEpatents

    Martens, Jon S.; Hietala, Vincent M.; Plut, Thomas A.

    1995-01-01

    The present invention comprises a novel matrix amplifier. The matrix amplifier includes an active superconducting power divider (ASPD) having N output ports; N distributed amplifiers each operatively connected to one of the N output ports of the ASPD; and a power combiner having N input ports each operatively connected to one of the N distributed amplifiers. The distributed amplifier can included M stages of amplification by cascading superconducting active devices. The power combiner can include N active elements. The resulting (N.times.M) matrix amplifier can produce signals of high output power, large bandwidth, and low noise.

  15. Mueller matrix differential decomposition.

    PubMed

    Ortega-Quijano, Noé; Arce-Diego, José Luis

    2011-05-15

    We present a Mueller matrix decomposition based on the differential formulation of the Mueller calculus. The differential Mueller matrix is obtained from the macroscopic matrix through an eigenanalysis. It is subsequently resolved into the complete set of 16 differential matrices that correspond to the basic types of optical behavior for depolarizing anisotropic media. The method is successfully applied to the polarimetric analysis of several samples. The differential parameters enable one to perform an exhaustive characterization of anisotropy and depolarization. This decomposition is particularly appropriate for studying media in which several polarization effects take place simultaneously. PMID:21593943

  16. Measurement matrix optimization method based on matrix orthogonal similarity transformation

    NASA Astrophysics Data System (ADS)

    Pan, Jinfeng

    2016-05-01

    Optimization of the measurement matrix is one of the important research aspects of compressive sensing theory. A measurement matrix optimization method is presented based on the orthogonal similarity transformation of the information operator's Gram matrix. In terms of the fact that the information operator's Gram matrix is a singular symmetric matrix, a simplified orthogonal similarity transformation is deduced, and thus the simplified diagonal matrix that is orthogonally similar to it is obtained. Then an approximation of the Gram matrix is obtained by letting all the nonzero diagonal entries of the simplified diagonal matrix equal their average value. Thus an optimized measurement matrix can be acquired according to its relationship with the information operator. Results of experiments show that the optimized measurement matrix compared to the random measurement matrix is less coherent with dictionaries. The relative signal recovery error also declines when the proposed measurement matrix is utilized.

  17. On lossless switched-capacitor power converters

    SciTech Connect

    Tse, C.K.; Wong, S.C.; Chow, M.H.L.

    1995-05-01

    This paper addresses the design of efficient switched-capacitor power converters. The discussion starts with a review of the fundamental limitation of switched-capacitor circuits which shows that the topology of such circuits and the ``forced`` step changes of capacitor voltages are the inherent attributes of power loss. Although the argument follows from a rather trivial result from basic circuit theory, it addresses an important issue on the maximum efficiency achievable in a switched-capacitor converter circuit. Based on the observed topological constraint of switched-capacitor converter circuits, the simplest lossless topology for AC/DC conversion is deduced. Also discussed is a simple version of lossless topology that achieves isolation between the source and the load. Finally, an experimental AC/DC switched-capacitor converter, based on the proposed idea, is presented which demonstrates an improved efficiency over other existing switched-capacitor converters. The proposed AC/DC converter contains no inductors and thus is suitable for custom IC implementation for very low power applications.

  18. Pesticide-Exposure Matrix

    Cancer.gov

    The "Pesticide-exposure Matrix" was developed to help epidemiologists and other researchers identify the active ingredients to which people were likely exposed when their homes and gardens were treated for pests in past years.

  19. Modelling and Simulation of Digital Compensation Technique for dc-dc Converter by Pole Placement

    NASA Astrophysics Data System (ADS)

    Shenbagalakshmi, R.; Sree Renga Raja, T.

    2015-09-01

    A thorough and effective analysis of the dc-dc converters is carried out in order to achieve the system stability and to improve the dynamic performance. A small signal modelling based on state space averaging technique for dc-dc converters is carried out. A digital state feedback gain matrix is derived by pole placement technique in order to achieve the stability of a completely controllable system. A prediction observer for the dc-dc converters is designed and a dynamic compensation (observer plus control law) is provided using separation principle. The output is very much improved with zero output voltage ripples, zero peak overshoot, and much lesser settling time in the range of ms and with higher overall efficiency (>90 %).

  20. 31 CFR 363.164 - Is a converted savings bond eligible to be converted back into a definitive bond?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... to be converted back into a definitive bond? 363.164 Section 363.164 Money and Finance: Treasury... Bond § 363.164 Is a converted savings bond eligible to be converted back into a definitive bond? Once a definitive savings bond has been converted to a book-entry bond, it may not be converted back into...

  1. Matrix fractional systems

    NASA Astrophysics Data System (ADS)

    Tenreiro Machado, J. A.

    2015-08-01

    This paper addresses the matrix representation of dynamical systems in the perspective of fractional calculus. Fractional elements and fractional systems are interpreted under the light of the classical Cole-Cole, Davidson-Cole, and Havriliak-Negami heuristic models. Numerical simulations for an electrical circuit enlighten the results for matrix based models and high fractional orders. The conclusions clarify the distinction between fractional elements and fractional systems.

  2. Optical coherency matrix tomography

    NASA Astrophysics Data System (ADS)

    Kagalwala, Kumel H.; Kondakci, H. Esat; Abouraddy, Ayman F.; Saleh, Bahaa E. A.

    2015-10-01

    The coherence of an optical beam having multiple degrees of freedom (DoFs) is described by a coherency matrix G spanning these DoFs. This optical coherency matrix has not been measured in its entirety to date—even in the simplest case of two binary DoFs where G is a 4 × 4 matrix. We establish a methodical yet versatile approach—optical coherency matrix tomography—for reconstructing G that exploits the analogy between this problem in classical optics and that of tomographically reconstructing the density matrix associated with multipartite quantum states in quantum information science. Here G is reconstructed from a minimal set of linearly independent measurements, each a cascade of projective measurements for each DoF. We report the first experimental measurements of the 4 × 4 coherency matrix G associated with an electromagnetic beam in which polarization and a spatial DoF are relevant, ranging from the traditional two-point Young’s double slit to spatial parity and orbital angular momentum modes.

  3. Optical coherency matrix tomography

    PubMed Central

    Kagalwala, Kumel H.; Kondakci, H. Esat; Abouraddy, Ayman F.; Saleh, Bahaa E. A.

    2015-01-01

    The coherence of an optical beam having multiple degrees of freedom (DoFs) is described by a coherency matrix G spanning these DoFs. This optical coherency matrix has not been measured in its entirety to date—even in the simplest case of two binary DoFs where G is a 4 × 4 matrix. We establish a methodical yet versatile approach—optical coherency matrix tomography—for reconstructing G that exploits the analogy between this problem in classical optics and that of tomographically reconstructing the density matrix associated with multipartite quantum states in quantum information science. Here G is reconstructed from a minimal set of linearly independent measurements, each a cascade of projective measurements for each DoF. We report the first experimental measurements of the 4 × 4 coherency matrix G associated with an electromagnetic beam in which polarization and a spatial DoF are relevant, ranging from the traditional two-point Young’s double slit to spatial parity and orbital angular momentum modes. PMID:26478452

  4. Stabilisation of matrix polynomials

    NASA Astrophysics Data System (ADS)

    Galindo, R.

    2015-10-01

    A state feedback is proposed to analyse the stability of a matrix polynomial in closed loop. First, it is shown that a matrix polynomial is stable if and only if a state space realisation of a ladder form of certain transfer matrix is stable. Following the ideas of the Routh-Hurwitz stability procedure for scalar polynomials, certain continued-fraction expansions of polynomial matrices are carrying out by unimodular matrices to achieve the Euclid's division algorithm which leads to an extension of the well-known Routh-Hurwitz stability criteria but this time in terms of matrix coefficients. After that, stability of the closed-loop matrix polynomial is guaranteed based on a Corollary of a Lyapunov Theorem. The sufficient stability conditions are: (i) The matrices of one column of the presented array must be symmetric and positive definite and (ii) the matrices of the cascade realisation must satisfy a commutative condition. These stability conditions are also necessary for matrix polynomial of second order. The results are illustrated through examples.

  5. Isolated and soft-switched power converter

    DOEpatents

    Peng, Fang Zheng; Adams, Donald Joe

    2002-01-01

    An isolated and soft-switched power converter is used for DC/DC and DC/DC/AC power conversion. The power converter includes two resonant tank circuits coupled back-to-back through an isolation transformer. Each resonant tank circuit includes a pair of resonant capacitors connected in series as a resonant leg, a pair of tank capacitors connected in series as a tank leg, and a pair of switching devices with anti-parallel clamping diodes coupled in series as resonant switches and clamping devices for the resonant leg. The power converter is well suited for DC/DC and DC/DC/AC power conversion applications in which high-voltage isolation, DC to DC voltage boost, bidirectional power flow, and a minimal number of conventional switching components are important design objectives. For example, the power converter is especially well suited to electric vehicle applications and load-side electric generation and storage systems, and other applications in which these objectives are important. The power converter may be used for many different applications, including electric vehicles, hybrid combustion/electric vehicles, fuel-cell powered vehicles with low-voltage starting, remote power sources utilizing low-voltage DC power sources, such as photovoltaics and others, electric power backup systems, and load-side electric storage and generation systems.

  6. Efficiency of Thermionic and Thermoelectric Converters

    NASA Astrophysics Data System (ADS)

    Gerstenmaier, York Christian; Wachutka, Gerhard

    2007-02-01

    Thermoelectric and thermionic converters — also in micro- and nano-meter design — are considered for power generation and cooling applications. The potential of thermionic vacuum gap converters is investigated precisely by a new advanced theory with inclusion of backward currents from the 2nd electrode, losses due to thermal radiation and ohmic resistance in the electrodes, tunneling through the gap, image forces, and space charge effects. The efficiency of nano-meter gap thermionic converters is by far higher than for thermoelectric devices (including nano-structured superlattices) for operating temperatures above 800°K, however, there is no chance of realization with today's technology. For a vacuum gap width of about 1 μm the performance is higher than for hypothetical bulk- thermoelectric generators (TEGs) with ZT = 1 for T > 1000°K and also higher than for hypothetical nano-structured superlattices (ZT = 2.4) for T > 1200°K. A thermionic converter with gap width of 5μm has lower performance than a TEG with ZT = 1, however, also operates at T > 1200°K. Reasonable performance of thermionic converters at T ⩽ 500°K necessitates materials with workfunctions ⩽ 0.5 eV.

  7. Fabrication and life testing of thermionic converters

    NASA Technical Reports Server (NTRS)

    Yang, L.; Bruce, R.

    1973-01-01

    An unfueled converter containing a chloride-fluoride duplex tungsten emitter of 4.78 eV vacuum work function was tested for 46,647 hours at an emitter temperature of 1973 K and an electrode power output of about 8 watts/sq cm. The test demonstrated the superior and stable performance of the (110) oriented tungsten emitter at high temperatures. Three 90 UC-10 ZrC(C/U = 1.04, tungsten additive = 4 wt %) fueled converters were fabricated and tested at an emitter temperature of 1873 K. Converter containing chloride-arc-cast duplex tungsten cladding showed temperature thermionic performance and slower rate of performance drop than converter containing chloride-fluoride duplex tungsten cladding. This is believed to be due to the superior fuel component diffusion resistance of the arc-cast tungsten substrate used in the fuel cladding. It was shown that a converter containing a carbide fueled chloride-arc-cast duplex tungsten emitter with an initial electrode power output of 6.80 watts/sq cm could still deliver an electrode power output of 6.16 watts/sq cm after 18,632 hours of operation at an emitter temperature of 1873 K.

  8. Ac-dc converter firing error detection

    SciTech Connect

    Gould, O.L.

    1996-07-15

    Each of the twelve Booster Main Magnet Power Supply modules consist of two three-phase, full-wave rectifier bridges in series to provide a 560 VDC maximum output. The harmonic contents of the twelve-pulse ac-dc converter output are multiples of the 60 Hz ac power input, with a predominant 720 Hz signal greater than 14 dB in magnitude above the closest harmonic components at maximum output. The 720 Hz harmonic is typically greater than 20 dB below the 500 VDC output signal under normal operation. Extracting specific harmonics from the rectifier output signal of a 6, 12, or 24 pulse ac-dc converter allows the detection of SCR firing angle errors or complete misfires. A bandpass filter provides the input signal to a frequency-to-voltage converter. Comparing the output of the frequency-to-voltage converter to a reference voltage level provides an indication of the magnitude of the harmonics in the ac-dc converter output signal.

  9. Materials technology for Stirling space power converters

    NASA Technical Reports Server (NTRS)

    Baggenstoss, William; Mittendorf, Donald

    1992-01-01

    This program was conducted in support of the NASA LeRC development of the Stirling power converter (SPC) for space power applications. The objectives of this contract were: (1) to perform a technology review and analyses to support the evaluation of materials issues for the SPC; (2) to evaluate liquid metal compatibility issues of the SPC; (3) to evaluate and define a transient liquid phase diffusion bonding (TLPDB) process for the SPC joints to the Udimet 720 heater head; and (4) to evaluate alternative (to the TLPDB) joining techniques. In the technology review, several aspects of the current Stirling design were examined including the power converter assembly process, materials joining, gas bearings, and heat exchangers. The supporting analyses included GLIMPS power converter simulation in support of the materials studies, and system level analysis in support of the technology review. The liquid metal compatibility study evaluated process parameters for use in the Stirling power converter. The alternative joining techniques study looked at the applicability of various joining techniques to the Stirling power converter requirements.

  10. Systems and methods for reducing transient voltage spikes in matrix converters

    DOEpatents

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

    2013-06-11

    Systems and methods are provided for delivering energy using an energy conversion module that includes one or more switching elements. An exemplary electrical system comprises a DC interface, an AC interface, an isolation module, a first conversion module between the DC interface and the isolation module, and a second conversion module between the AC interface and the isolation module. A control module is configured to operate the first conversion module to provide an injection current to the second conversion module to reduce a magnitude of a current through a switching element of the second conversion module before opening the switching element.

  11. Matrix interdiction problem

    SciTech Connect

    Pan, Feng; Kasiviswanathan, Shiva

    2010-01-01

    In the matrix interdiction problem, a real-valued matrix and an integer k is given. The objective is to remove k columns such that the sum over all rows of the maximum entry in each row is minimized. This combinatorial problem is closely related to bipartite network interdiction problem which can be applied to prioritize the border checkpoints in order to minimize the probability that an adversary can successfully cross the border. After introducing the matrix interdiction problem, we will prove the problem is NP-hard, and even NP-hard to approximate with an additive n{gamma} factor for a fixed constant {gamma}. We also present an algorithm for this problem that achieves a factor of (n-k) mUltiplicative approximation ratio.

  12. Hydrodynamic Performance of a Wave Energy Converter

    NASA Astrophysics Data System (ADS)

    Yang, Yingchen

    2010-11-01

    To harvest energy from ocean waves, a new wave energy converter (WEC) was proposed and tested in a wave tank. The WEC freely floats on the water surface and rides waves. It utilizes its wave-driven angular oscillation to convert the mechanical energy of waves into electricity. To gain the maximum possible angular oscillation of the WEC under specified wave conditions, both floatation of the WEC and wave interaction with the WEC play critical roles in a joint fashion. During the experiments, the submersion condition of the WEC and wave condition were varied. The results were analyzed in terms of the oscillation amplitude, stability, auto-orientation capability, and wave frequency dependency.

  13. WEC-Sim (Wave Energy Converter - SIMulator)

    2014-11-26

    WEC-Sim (Wave Energy Converter SIMulator) is a code developed by Sandia National Laboratories and the National Renewable Energy Laboratory to model wave energy converters (WECs) when they are subject to operational waves. The code is a time-domain modeling tool developed in MATLAB/Simulink using the multi-body dynamics solver SimMechanics. In WEC-Sim, WECs are modeled by connecting rigid bodies to one another with joint or constraint blocks from the WEC-Sim library. WEC-Sim is a publicly available, open-sourcemore » code to model WECs.« less

  14. WEC-Sim (Wave Energy Converter - SIMulator)

    SciTech Connect

    2014-11-26

    WEC-Sim (Wave Energy Converter SIMulator) is a code developed by Sandia National Laboratories and the National Renewable Energy Laboratory to model wave energy converters (WECs) when they are subject to operational waves. The code is a time-domain modeling tool developed in MATLAB/Simulink using the multi-body dynamics solver SimMechanics. In WEC-Sim, WECs are modeled by connecting rigid bodies to one another with joint or constraint blocks from the WEC-Sim library. WEC-Sim is a publicly available, open-source code to model WECs.

  15. Converting virtual community members into online buyers.

    PubMed

    Gupta, Sumeet; Kim, Hee-Woong; Shin, Seon-Jin

    2010-10-01

    Although many online vendors have sponsored virtual communities (VCs) in the hope of reaping commercial benefits from it, not many have been successful in reaping commercial benefits from their VC. Online vendors can benefit greatly from having a VC, if the VC members can be converted into online buyers. This study examines the conversion of a VC member into an online buyer. Using a classical-conditioning approach, this study finds that members' committed participation in the VC is the springboard for online vendors to convert VC members into online buyers.

  16. Combination solar photovoltaic heat engine energy converter

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.

    1987-01-01

    A combination solar photovoltaic heat engine converter is proposed. Such a system is suitable for either terrestrial or space power applications. The combination system has a higher efficiency than either the photovoltaic array or the heat engine alone can attain. Advantages in concentrator and radiator area and receiver mass of the photovoltaic heat engine system over a heat-engine-only system are estimated. A mass and area comparison between the proposed space station organic Rankine power system and a combination PV-heat engine system is made. The critical problem for the proposed converter is the necessity for high temperature photovoltaic array operation. Estimates of the required photovoltaic temperature are presented.

  17. Solar energy converter using surface plasma waves

    NASA Technical Reports Server (NTRS)

    Anderson, L. M. (Inventor)

    1984-01-01

    Sunlight is dispersed over a diffraction grating formed on the surface of a conducting film on a substrate. The angular dispersion controls the effective grating period so that a matching spectrum of surface plasmons is excited for parallel processing on the conducting film. The resulting surface plasmons carry energy to an array of inelastic tunnel diodes. This solar energy converter does not require different materials for each frequency band, and sunlight is directly converted to electricity in an efficient manner by extracting more energy from the more energetic photons.

  18. Electrodes For Alkali-Metal Thermoelectric Converters

    NASA Technical Reports Server (NTRS)

    Williams, Roger M.; Wheeler, Bob L.; Jeffries-Nakamura, Barbara; Lamb, James L.; Bankston, C. Perry; Cole, Terry

    1989-01-01

    Combination of thin, porous electrode and overlying collector grid reduces internal resistance of alkali-metal thermoelectric converter cell. Low resistance of new electrode and grid boosts power density nearly to 1 W/cm2 of electrode area at typical operating temperatures of 1,000 to 1,300 K. Conductive grid encircles electrode film on alumina tube. Bus wire runs along tube to collect electrical current from grid. Such converters used to transform solar, nuclear, and waste heat into electric power.

  19. Potential converter for laser-power beaming

    NASA Technical Reports Server (NTRS)

    Walker, Gilbert H.; Williams, Michael D.; Schuster, Gregory L.; Iles, Peter A.

    1991-01-01

    Future space missions, such as those associated with the Space Exploration Initiative (SEI), will require large amounts of power for operation of bases, rovers, and orbit transfer vehicles. One method for supplying this power is to beam power from a spaced based or Earth based laser power station to a receiver where laser photons can be converted to electricity. Previous research has described such laser power stations orbiting the Moon and beaming power to a receiver on the surface of the Moon by using arrays of diode lasers. Photovoltaic converters that can be efficiently used with these diode lasers are described.

  20. Converting ODM Metadata to FHIR Questionnaire Resources.

    PubMed

    Doods, Justin; Neuhaus, Philipp; Dugas, Martin

    2016-01-01

    Interoperability between systems and data sharing between domains is becoming more and more important. The portal medical-data-models.org offers more than 5.300 UMLS annotated forms in CDISC ODM format in order to support interoperability, but several additional export formats are available. CDISC's ODM and HL7's framework FHIR Questionnaire resource were analyzed, a mapping between elements created and a converter implemented. The developed converter was integrated into the portal with FHIR Questionnaire XML or JSON download options. New FHIR applications can now use this large library of forms. PMID:27577424

  1. Convergence of Density-Matrix Expansions for Nuclear Interactions

    SciTech Connect

    Carlsson, B. G.; Dobaczewski, J.

    2010-09-17

    We extend density-matrix expansions in nuclei to higher orders in derivatives of densities and test their convergence properties. The expansions allow for converting the interaction energies characteristic to finite- and short-range nuclear effective forces into quasilocal density functionals. We also propose a new type of expansion that has excellent convergence properties when benchmarked against the binding energies obtained for the Gogny interaction.

  2. Matrixed business support comparison study.

    SciTech Connect

    Parsons, Josh D.

    2004-11-01

    The Matrixed Business Support Comparison Study reviewed the current matrixed Chief Financial Officer (CFO) division staff models at Sandia National Laboratories. There were two primary drivers of this analysis: (1) the increasing number of financial staff matrixed to mission customers and (2) the desire to further understand the matrix process and the opportunities and challenges it creates.

  3. 40 CFR 91.319 - NOX converter check.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 20 2011-07-01 2011-07-01 false NOX converter check. 91.319 Section 91... converter check. (a) The efficiency of the converter used for the conversion of NO2 to NO is tested as given... efficiency of converters by means of an ozonator. (2) Calibrate the HCLD in the most common operating...

  4. Lathe converted for grinding aspheric surfaces

    NASA Technical Reports Server (NTRS)

    Larmer, J. W.; Levinsohn, M.; Mc Craw, D.; Pessagno, E. H.; Taub, F. J.

    1964-01-01

    A standard overarm tracing lathe converted by the addition of an independently driven diamond grinding wheel is used for grinding aspheric surfaces. The motion of the wheel is controlled by the lathe air tracer following the template which produces the desired aspheric profile.

  5. Converting Student Support Services to Online Delivery.

    ERIC Educational Resources Information Center

    Brigham, David E.

    2001-01-01

    Uses a systems framework to analyze the creation of student support services for distance education at Regents College: electronic advising, electronic peer network, online course database, online bookstore, virtual library, and alumni services website. Addresses the issues involved in converting distance education programs from print-based and…

  6. Assay for Angiotensin-Converting Enzyme.

    ERIC Educational Resources Information Center

    Russo, Salvatore F.

    1983-01-01

    Describes a three-hour experiment designed to introduce students to chemistry of the angiotensis-converting enzyme, illustrate design of a quenched fluorescence substrate, and examine considerations necessary in designing a clinical assay. Includes background information on the biochemistry of hypertension, reagents/materials needed, procedures…

  7. Offset compensation for A/D converters

    NASA Technical Reports Server (NTRS)

    Brokl, S. S.; Hurd, W. J.

    1979-01-01

    Analog-to-digital (A/D) converter eliminates dc offset in final digitized signal as well as in analog input by using digital feedback for compensation. Circuit could prove useful in data processing applications in which analog-format data are entered at high rates, as in point-of-sale data input systems.

  8. Catalytic Converters Maintain Air Quality in Mines

    NASA Technical Reports Server (NTRS)

    2014-01-01

    At Langley Research Center, engineers developed a tin-oxide based washcoat to prevent oxygen buildup in carbon dioxide lasers used to detect wind shears. Airflow Catalyst Systems Inc. of Rochester, New York, licensed the technology and then adapted the washcoat for use as a catalytic converter to treat the exhaust from diesel mining equipment.

  9. Hybrid switch for resonant power converters

    DOEpatents

    Lai, Jih-Sheng; Yu, Wensong

    2014-09-09

    A hybrid switch comprising two semiconductor switches connected in parallel but having different voltage drop characteristics as a function of current facilitates attainment of zero voltage switching and reduces conduction losses to complement reduction of switching losses achieved through zero voltage switching in power converters such as high-current inverters.

  10. Does nature convert mass into energy?

    NASA Astrophysics Data System (ADS)

    Baierlein, Ralph

    2007-04-01

    First I provide some history of how the equation E =mc2 arose, establish what "mass" means in the context of this relation, and present some aspects of how the relation can be understood. Then I address the question, Does E =mc2 mean that one can "convert mass into energy" and vice versa?

  11. Efficient, lightweight dc/dc switching converter

    NASA Technical Reports Server (NTRS)

    Cuk, S.; Middlebrook, R. D.

    1981-01-01

    Converters have input properties of boost power stage and output properties of buck power stage, yet they perform general conversion function with high efficiency. Other features include non-pulsating input/output currents, use of capacitive energy transfer, low output voltage ripple, reduced EMI, and small size.

  12. Multilevel converters for large electric drives

    SciTech Connect

    Tolbert, L.M.; Peng, F.Z.

    1997-11-01

    Traditional two-level high frequency pulse width modulation (PWM) inverters for motor drives have several problems associated with their high frequency switching which produces common-mode voltage and high voltage change (dV/dt) rates to the motor windings. Multilevel inverters solve these problems because their devices can switch at a much lower frequency. Two different multilevel topologies are identified for use as a converter for electric drives, a cascade inverter with separate dc sources and a back-to-back diode clamped converter. The cascade inverter is a natural fit for large automotive all electric drives because of the high VA ratings possible and because it uses several levels of dc voltage sources which would be available from batteries or fuel cells. The back to back diode damped converter is ideal where a source of ac voltage is available such as a hybrid electric vehicle. Simulation and experimental results show the superiority of these two converters over PWM based drives.

  13. Angiotensin converting enzyme of Thalassophryne nattereri venom.

    PubMed

    da Costa Marques, Maria Elizabeth; de Araújo Tenório, Humberto; Dos Santos, Claudio Wilian Victor; Dos Santos, Daniel Moreira; de Lima, Maria Elena; Pereira, Hugo Juarez Vieira

    2016-10-01

    Animal venoms are complex mixtures, including peptides, proteins (i.e., enzymes), and other compounds produced by animals in predation, digestion, and defense. These molecules have been investigated regarding their molecular mechanisms associated with physiological action and possible pharmacological applications. Recently, we have described the presence of a type of angiotensin converting enzyme (ACE) activity in the venom of Thalassophryne nattereri. It is a zinc-dependent peptidase with a wide range of effects. By removing dipeptide His-Leu from terminal C, the ACE converts angiotensinI (AngI) into angiotensin II (AngII) and inactivates bradykinin, there by regulating blood pressure and electrolyte homeostasis. The fractionation of T. nattereri venom in CM-Sepharose indicated a peak (CM2) with angiotensin-converting activity, converting AngI into Ang II. Electrophoresis on polyacrylamide gel (12%) revealed one band with 30kDa for CM2 similar in size to natterins, which are toxins with proteolytic activity found in T. nattereri venom. Mass spectrometry indicated that the protein sequence of the ACE purified from T. nattereri venom corresponds to natterin 1. The isolated protein has also demonstrated inhibition through captopril and EDTA and is characterized as a classic ACE. Thus, the isolated enzyme purified from T. nattereri venom is the first ACE isolated from fish venom.

  14. Convert natural gas into clean transportation fuels

    SciTech Connect

    Agee, M.A.

    1997-03-01

    A new process economically converts natural gas into synthetic transportation fuels that are free of sulfur, metals, aromatics and are clear in appearance. The process, developed by Syntroleum Corp., is energy self-sufficient and can be implemented in sizes small enough to fit a large number of the world`s gas fields. The process is described.

  15. Fuel densifier converts biomass into fuel cubes

    SciTech Connect

    Not Available

    1982-02-01

    A new cost-effective means to produce clean-burning and low cost commercial and industrial fuel is being introduced by Columbia Fuel Densification Corp., Phoenix. The Columbia Commercial Hydraulic Fuel Densifier converts raw biomass materials such as wood chips, paper, peat moss and rice hulls into densified fuel cubes. The densifier is mobile and its operation is briefly outlined.

  16. STIFF: Converting Scientific FITS Images to TIFF

    NASA Astrophysics Data System (ADS)

    Bertin, Emmanuel

    2011-10-01

    STIFF is a program that converts scientific FITS1 images to the more popular TIFF2 format for illustration purposes. Most FITS readers and converters do not do a proper job at converting FITS image data to 8 bits. 8-bit images stored in JPEG, PNG or TIFF files have the intensities implicitely stored in a non-linear way. Most current FITS image viewers and converters provide the user an incorrect translation of the FITS image content by simply rescaling linearly input pixel values. A first consequence is that the people working on astronomical images usually have to apply narrow intensity cuts or square-root or logarithmic intensity transformations to actually see something on their deep-sky images. A less obvious consequence is that colors obtained by combining images processed this way are not consistent across such a large range of surface brightnesses. Though with other software the user is generally afforded a choice of nonlinear transformations to apply in order to make the faint stuff stand out more clearly in the images, with the limited selection of choices provides, colors will not be accurately rendered, and some manual tweaking will be necessary. The purpose of STIFF is to produce beautiful pictures in an automatic and consistent way.

  17. Angiotensin converting enzyme of Thalassophryne nattereri venom.

    PubMed

    da Costa Marques, Maria Elizabeth; de Araújo Tenório, Humberto; Dos Santos, Claudio Wilian Victor; Dos Santos, Daniel Moreira; de Lima, Maria Elena; Pereira, Hugo Juarez Vieira

    2016-10-01

    Animal venoms are complex mixtures, including peptides, proteins (i.e., enzymes), and other compounds produced by animals in predation, digestion, and defense. These molecules have been investigated regarding their molecular mechanisms associated with physiological action and possible pharmacological applications. Recently, we have described the presence of a type of angiotensin converting enzyme (ACE) activity in the venom of Thalassophryne nattereri. It is a zinc-dependent peptidase with a wide range of effects. By removing dipeptide His-Leu from terminal C, the ACE converts angiotensinI (AngI) into angiotensin II (AngII) and inactivates bradykinin, there by regulating blood pressure and electrolyte homeostasis. The fractionation of T. nattereri venom in CM-Sepharose indicated a peak (CM2) with angiotensin-converting activity, converting AngI into Ang II. Electrophoresis on polyacrylamide gel (12%) revealed one band with 30kDa for CM2 similar in size to natterins, which are toxins with proteolytic activity found in T. nattereri venom. Mass spectrometry indicated that the protein sequence of the ACE purified from T. nattereri venom corresponds to natterin 1. The isolated protein has also demonstrated inhibition through captopril and EDTA and is characterized as a classic ACE. Thus, the isolated enzyme purified from T. nattereri venom is the first ACE isolated from fish venom. PMID:27327905

  18. Converting neutron stars into strange stars

    NASA Technical Reports Server (NTRS)

    Olinto, A. V.

    1991-01-01

    If strange matter is formed in the interior of a neutron star, it will convert the entire neutron star into a strange star. The proposed mechanisms are reviewed for strange matter seeding and the possible strange matter contamination of neutron star progenitors. The conversion process that follows seeding and the recent calculations of the conversion timescale are discussed.

  19. The Acrosomal Matrix.

    PubMed

    Foster, James A; Gerton, George L

    2016-01-01

    The acrosome, a single exocytotic vesicle on the head of sperm, has an essential role in fertilization, but the exact mechanisms by which it facilitates sperm-egg interactions remain unresolved. The acrosome contains dozens of secretory proteins that are packaged into the forming structure during spermatogenesis; many of these proteins are localized into specific topographical areas of the acrosome, while others are more diffusely distributed. Acrosomal proteins can also be biochemically classified as components of the acrosomal matrix, a large, relatively insoluble complex, or as soluble proteins. This review focuses on recent findings using genetically modified mice (gene knockouts and transgenic "green acrosome" mice) to study the effects of eliminating acrosomal matrix-associated proteins on sperm structure and function. Some gene knockouts produce infertile phenotypes with obviously missing, specific activities that affect acrosome biogenesis during spermatogenesis or interfere with acrosome function in mature sperm. Mutations that delete some components produce fertile phenotypes with subtler effects that provide useful insights into acrosomal matrix function in fertilization. In general, these studies enable the reassessment of paradigms to explain acrosome formation and function and provide novel, objective insights into the roles of acrosomal matrix proteins in fertilization. The use of genetically engineered mouse models has yielded new mechanistic information that complements recent, important in vivo imaging studies. PMID:27194348

  20. Constructing the matrix

    NASA Astrophysics Data System (ADS)

    Elliott, John

    2012-09-01

    As part of our 'toolkit' for analysing an extraterrestrial signal, the facility for calculating structural affinity to known phenomena must be part of our core capabilities. Without such a resource, we risk compromising our potential for detection and decipherment or at least causing significant delay in the process. To create such a repository for assessing structural affinity, all known systems (language parameters) need to be structurally analysed to 'place' their 'system' within a relational communication matrix. This will need to include all known variants of language structure, whether 'living' (in current use) or ancient; this must also include endeavours to incorporate yet undeciphered scripts and non-human communication, to provide as complete a picture as possible. In creating such a relational matrix, post-detection decipherment will be assisted by a structural 'map' that will have the potential for 'placing' an alien communication with its nearest known 'neighbour', to assist subsequent categorisation of basic parameters as a precursor to decipherment. 'Universal' attributes and behavioural characteristics of known communication structure will form a range of templates (Elliott, 2001 [1] and Elliott et al., 2002 [2]), to support and optimise our attempt at categorising and deciphering the content of an extraterrestrial signal. Detection of the hierarchical layers, which comprise intelligent, complex communication, will then form a matrix of calculations that will ultimately score affinity through a relational matrix of structural comparison. In this paper we develop the rationales and demonstrate functionality with initial test results.

  1. Matrix Embedded Organic Synthesis

    NASA Astrophysics Data System (ADS)

    Kamakolanu, U. G.; Freund, F. T.

    2016-05-01

    In the matrix of minerals such as olivine, a redox reaction of the low-z elements occurs. Oxygen is oxidized to the peroxy state while the low-Z-elements become chemically reduced. We assign them a formula [CxHyOzNiSj]n- and call them proto-organics.

  2. A low-voltage boost converter using a forward converter with integrated Meissner oscillator

    NASA Astrophysics Data System (ADS)

    Woias, P.; Islam, M.; Heller, S.; Roth, R.

    2013-12-01

    This paper describes a novel boost converter to be used with energy harvesters that provide only low output voltages. The device is self-supplied from electric power delivered to its input. With peak power conversion efficiencies above 30% at start-up voltages down to 10 mV this circuit sets best values in comparison with the state-of-the-art. This is achieved by the novel combination of a Meissner oscillator, used as stand-alone in most low-voltage step-up converters today, with a forward converter usually applied in high power systems.

  3. 31 CFR 363.164 - Is a converted savings bond eligible to be converted back into a definitive bond?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 31 Money and Finance: Treasury 2 2010-07-01 2010-07-01 false Is a converted savings bond eligible to be converted back into a definitive bond? 363.164 Section 363.164 Money and Finance: Treasury... Bond § 363.164 Is a converted savings bond eligible to be converted back into a definitive bond? Once...

  4. 100kW Energy Transfer Multiplexer Power Converter Prototype Development Project

    SciTech Connect

    S. Merrill Skeist; Richard H. Baker; Anthony G.P. Marini; DOE Project Officer - Keith Bennett

    2006-03-21

    Project Final Report for "100kW Energy Transfer Multiplexer Power Converter Prototype Development Project" prepared under DOE grant number DE-FG36-03GO13138. This project relates to the further development and prototype construction/evaluation for the Energy Transfer Multiplexer (ETM) power converter topology concept. The ETM uses a series resonant link to transfer energy from any phase of a multiphase input to any phase of a multiphase output, converting any input voltage and frequency to any output voltage and frequency. The basic form of the ETM converter consists of an eight (8)-switch matrix (six phase power switches and two ground power switches) and a series L-C resonant circuit. Electronic control of the switches allows energy to be transferred in the proper amount from any phase to any other phase. Depending upon the final circuit application, the switches may be either SCRs or IGBTs. The inherent characteristics of the ETM converter include the following: Power processing in either direction (bidirectional); Large voltage gain without the need of low frequency magnetics; High efficiency independent of output load and frequency; Wide bandwidth with fast transient response and; Operation as a current source. The ETM is able to synthesize true sinusoidal waveforms with low harmonic distortions. For a low power PM wind generation system, the ETM has the following characteristics and advantages: It provides voltage gain without the need of low frequency magnetics (DC inductors) and; It has constant high efficiency independent of the load. The ETM converter can be implemented into a PM wind power system with smaller size, reduced weight and lower cost. As a result of our analyses, the ETM offers wind power generation technology for the reduction of the cost and size as well as the increase in performance of low power, low wind speed power generation. This project is the further theoretical/analytical exploration of the ETM converter concept in relationship to

  5. TiConverter: A training image converting tool for multiple-point geostatistics

    NASA Astrophysics Data System (ADS)

    Fadlelmula F., Mohamed M.; Killough, John; Fraim, Michael

    2016-11-01

    TiConverter is a tool developed to ease the application of multiple-point geostatistics whether by the open source Stanford Geostatistical Modeling Software (SGeMS) or other available commercial software. TiConverter has a user-friendly interface and it allows the conversion of 2D training images into numerical representations in four different file formats without the need for additional code writing. These are the ASCII (.txt), the geostatistical software library (GSLIB) (.txt), the Isatis (.dat), and the VTK formats. It performs the conversion based on the RGB color system. In addition, TiConverter offers several useful tools including image resizing, smoothing, and segmenting tools. The purpose of this study is to introduce the TiConverter, and to demonstrate its application and advantages with several examples from the literature.

  6. Optical shutter switching matrix

    NASA Technical Reports Server (NTRS)

    Grove, Charles H.

    1991-01-01

    The interface switching systems are discussed which are related to those used in the Space Shuttle ground control system, transmission systems, communications systems, and airborne radar electronic countermeasure systems. The main goal is to identify a need that exists throughout the comprehensive information processing and communications disciplines supporting the Space Shuttle and Space Station programs, and introduce one viable approach to satisfy that need. The proposed device, described in NASA patent entitled 'Optical Shutter Switch Matrix', is discussed.

  7. Metal matrix composite fuel for space radioisotope energy sources

    NASA Astrophysics Data System (ADS)

    Williams, H. R.; Ning, H.; Reece, M. J.; Ambrosi, R. M.; Bannister, N. P.; Stephenson, K.

    2013-02-01

    Radioisotope fuels produce heat that can be used for spacecraft thermal control or converted to electricity. They must retain integrity in the event of destruction or atmospheric entry of the parent spacecraft. Addition of a metal matrix to the actinide oxide could yield a more robust fuel form. Neodymium (III) oxide (Nd2O3) - niobium metal matrix composites were produced using Spark Plasma Sintering; Nd2O3 is a non-radioactive surrogate for americium (III) oxide (Am2O3). Two compositions, 70 and 50 wt% Nd2O3, were mechanically tested under equibiaxial (ring-on-ring) flexure according to ASTM C1499. The addition of the niobium matrix increased the mean flexural strength by a factor of about 2 compared to typical ceramic nuclear fuels, and significantly increased the Weibull modulus to over 20. These improved mechanical properties could result in reduced fuel dispersion in severe accidents and improved safety of space radioisotope power systems.

  8. Hypercube matrix computation task

    NASA Technical Reports Server (NTRS)

    Calalo, Ruel H.; Imbriale, William A.; Jacobi, Nathan; Liewer, Paulett C.; Lockhart, Thomas G.; Lyzenga, Gregory A.; Lyons, James R.; Manshadi, Farzin; Patterson, Jean E.

    1988-01-01

    A major objective of the Hypercube Matrix Computation effort at the Jet Propulsion Laboratory (JPL) is to investigate the applicability of a parallel computing architecture to the solution of large-scale electromagnetic scattering problems. Three scattering analysis codes are being implemented and assessed on a JPL/California Institute of Technology (Caltech) Mark 3 Hypercube. The codes, which utilize different underlying algorithms, give a means of evaluating the general applicability of this parallel architecture. The three analysis codes being implemented are a frequency domain method of moments code, a time domain finite difference code, and a frequency domain finite elements code. These analysis capabilities are being integrated into an electromagnetics interactive analysis workstation which can serve as a design tool for the construction of antennas and other radiating or scattering structures. The first two years of work on the Hypercube Matrix Computation effort is summarized. It includes both new developments and results as well as work previously reported in the Hypercube Matrix Computation Task: Final Report for 1986 to 1987 (JPL Publication 87-18).

  9. Thermophotovoltaic Converter Design for Radioisotope Power Systems

    NASA Astrophysics Data System (ADS)

    Crowley, Christopher J.; Murray, Susan; Murray, Christopher; Elkouh, Nabil A.

    2004-02-01

    The development of lightweight, efficient power for emerging NASA missions and recent advances in thermophotovoltaic (TPV) conversion technology have renewed interest in combining radioisotope heat sources with photovoltaic energy conversion. Thermophotovoltaic power conversion uses advanced materials able to utilize a broader, spectrally tuned range of wavelengths for more efficient power conversion than solar cells. Spectral control, including selective emitters, TPV module, and filters, are key to high-efficiency operation. This paper outlines the mechanical, thermal, and optical designs for the converter, including the heat source, the selective emitter, filters, photovoltaic (PV) cells, and optical cavity components. Focus is on the emitter type and the band-gap of InGaAs PV cells in developing the design. Any component and converter data available at the time of publication will also be presented.

  10. Analog current mode analog/digital converter

    NASA Technical Reports Server (NTRS)

    Hadidi, Khayrollah (Inventor)

    1996-01-01

    An improved subranging or comparator circuit is provided for an analog-to-digital converter. As a subranging circuit, the circuit produces a residual signal representing the difference between an analog input signal and an analog of a digital representation. This is achieved by subdividing the digital representation into two or more parts and subtracting from the analog input signal analogs of each of the individual digital portions. In another aspect of the present invention, the subranging circuit comprises two sets of differential input pairs in which the transconductance of one differential input pair is scaled relative to the transconductance of the other differential input pair. As a consequence, the same resistor string may be used for two different digital-to-analog converters of the subranging circuit.

  11. Integrated mode converter for mode division multiplexing

    NASA Astrophysics Data System (ADS)

    Perez-Galacho, Diego; Alonso-Ramos, Carlos Alberto; Marris-Morini, Delphine; Vakarin, Vladyslav; Le Roux, Xavier; Ortega-Moñux, Alejandro; Wangüemert-Perez, Juan Gonzalo; Vivien, Laurent

    2016-05-01

    The ever growing demands of bandwidth in optical communication systems are making traditional Wavelength Division Multiplexing (WDM) based systems to reach its limit. In order to cope with future bandwidth demand is necessary to use new levels of orthogonality, such as the waveguide mode or the polarization state. Mode Division Multiplexing (MDM) has recently attracted attention as a possible solution to increase aggregate bandwidth. In this work we discuss the proposition a of mode converter that can cover the whole C-Band of optical communications. The Mode Converter is based on two Multimode Interference (MMI) couplers and a phase shifter. Insertion loss (IL) below 0.2 dB and Extinction ratio (ER) higher than 20 dB in a broad bandwidth range of 1.5 μm to 1.6 μm have been estimated. The total length of the device is less than 30 μm.

  12. Segmented Thermoelectric Multicouple Converter Technology Development

    NASA Astrophysics Data System (ADS)

    Mondt, Jack; Johnson, Ken; Fleurial, Jean-Pierre; El Genk, Mohamed; Frye, Patrick; Determan, Bill

    2005-02-01

    The primary objectives of the segmented thermoelectric multicouple converter (STMC) technology development effort are: to define a conceptual design for a passive, low mass (3000 kg), long life (15 years) thermoelectric advanced Space Reactor Power System that provides 100kWe 400 Volt dc power for a 6000 volt dc electric propulsion system, to prepare a preliminary design of the power conversion system and to prepare technology development plan to advance power conversion system technology to TRL 6. The SRPS consists of a heat pipe cooled reactor radiatively couple to high efficiency solid-state segmented thermoelectric multicouple converters which are conductively coupled to a low mass heat pipe radiator. The SRPS conceptual design as well as the Power Conversion System preliminary design is complete and their description reported in this paper.

  13. Thermophotovoltaic Converter Design for Radioisotope Power Systems

    SciTech Connect

    Crowley, Christopher J.; Elkouh, Nabil A.; Murray, Susan; Murray, Christopher

    2004-02-04

    The development of lightweight, efficient power for emerging NASA missions and recent advances in thermophotovoltaic (TPV) conversion technology have renewed interest in combining radioisotope heat sources with photovoltaic energy conversion. Thermophotovoltaic power conversion uses advanced materials able to utilize a broader, spectrally tuned range of wavelengths for more efficient power conversion than solar cells. Spectral control, including selective emitters, TPV module, and filters, are key to high-efficiency operation. This paper outlines the mechanical, thermal, and optical designs for the converter, including the heat source, the selective emitter, filters, photovoltaic (PV) cells, and optical cavity components. Focus is on the emitter type and the band-gap of InGaAs PV cells in developing the design. Any component and converter data available at the time of publication will also be presented.

  14. Strained quantum well photovoltaic energy converter

    NASA Technical Reports Server (NTRS)

    Freundlich, Alexandre (Inventor); Renaud, Philippe (Inventor); Vilela, Mauro Francisco (Inventor); Bensaoula, Abdelhak (Inventor)

    1998-01-01

    An indium phosphide photovoltaic cell is provided where one or more quantum wells are introduced between the conventional p-conductivity and n-conductivity indium phosphide layer. The approach allows the cell to convert the light over a wider range of wavelengths than a conventional single junction cell and in particular convert efficiently transparency losses of the indium phosphide conventional cell. The approach hence may be used to increase the cell current output. A method of fabrication of photovoltaic devices is provided where ternary InAsP and InGaAs alloys are used as well material in the quantum well region and results in an increase of the cell current output.

  15. MOCCASIN: converting MATLAB ODE models to SBML

    PubMed Central

    Gómez, Harold F.; Hucka, Michael; Keating, Sarah M.; Nudelman, German; Iber, Dagmar; Sealfon, Stuart C.

    2016-01-01

    Summary: MATLAB is popular in biological research for creating and simulating models that use ordinary differential equations (ODEs). However, sharing or using these models outside of MATLAB is often problematic. A community standard such as Systems Biology Markup Language (SBML) can serve as a neutral exchange format, but translating models from MATLAB to SBML can be challenging—especially for legacy models not written with translation in mind. We developed MOCCASIN (Model ODE Converter for Creating Automated SBML INteroperability) to help. MOCCASIN can convert ODE-based MATLAB models of biochemical reaction networks into the SBML format. Availability and implementation: MOCCASIN is available under the terms of the LGPL 2.1 license (http://www.gnu.org/licenses/lgpl-2.1.html). Source code, binaries and test cases can be freely obtained from https://github.com/sbmlteam/moccasin. Contact: mhucka@caltech.edu Supplementary information: More information is available at https://github.com/sbmlteam/moccasin. PMID:26861819

  16. Real power measurement using a thermal converter

    NASA Astrophysics Data System (ADS)

    Möhring, Tobias; Spiegel, Thomas; Funck, Torsten

    2014-03-01

    In this paper, a new application of thermal converters is presented which allows energy, power and rms measurement without the need to substitute the measurement signal with a dc signal as performed in ac-dc transfer. Using a mathematical model of standard planar multijunction thermal converters (PMJTCs), the effective power acting inside the heater of the PMJTC is calculated from the output signal of its thermocouples. Due to the underlying physical principles, this method not only allows the calculation of the rms value of sinusoidal signals but also the average power and absolute energy contained in non-sinusoidal, non-periodic and even non-stationary signals, as appearing in the characterization of energy harvesters.

  17. MAGIC: Model and Graphic Information Converter

    NASA Technical Reports Server (NTRS)

    Herbert, W. C.

    2009-01-01

    MAGIC is a software tool capable of converting highly detailed 3D models from an open, standard format, VRML 2.0/97, into the proprietary DTS file format used by the Torque Game Engine from GarageGames. MAGIC is used to convert 3D simulations from authoritative sources into the data needed to run the simulations in NASA's Distributed Observer Network. The Distributed Observer Network (DON) is a simulation presentation tool built by NASA to facilitate the simulation sharing requirements of the Data Presentation and Visualization effort within the Constellation Program. DON is built on top of the Torque Game Engine (TGE) and has chosen TGE's Dynamix Three Space (DTS) file format to represent 3D objects within simulations.

  18. Series resonant converter using flyback control

    NASA Astrophysics Data System (ADS)

    Lee, H. T.; Josephs, L. C.

    Series resonant converters are widely used in applications requiring high power density. They offer several advantages over other topologies such as simplicity of design, switching at zero current levels, and high efficiency due to low switching losses. A new converter will be proposed that delivers pulses of equal energy to the load with comparatively small pulse-to-pulse delay and draws sinusoidal input current pulses. Also, the conventional charge and discharge cycle of the commutation capacitor is eliminated. The capacitor voltage is bidirectional and energy is transferred from the capacitor to the load during each switching cycle. This topology does not generate any abruptly discontinuous current waveforms, therefore, the EMI produced is minimal.

  19. Component technology for Stirling power converters

    SciTech Connect

    Thieme, L.G.

    1994-09-01

    NASA Lewis Research Center has organized a component technology program as part of the efforts to develop Stirling converter technology for space power applications. The Stirling space power program is part of the NASA High Capacity Power Project of the Civil Space Technology Initiative (CSTI). NASA Lewis is also providing technical management for a DOE/Sandia program to develop Stirling converters for solar terrestrial power producing electricity for the utility grid. The primary contractors for the space power and solar terrestrial programs develop component technologies directly related to their program goals. This Lewis component technology effort, while coordinated with the main programs, aims at longer term issues, advanced technologies, and independent assessments. This paper will present an overview of work on linear alternators, engine/alternator/load interactions and controls, heat exchangers, materials, life and reliability, and bearings.

  20. Component technology for stirling power converters

    NASA Technical Reports Server (NTRS)

    Thieme, Lanny G.

    1991-01-01

    NASA Lewis Research Center has organized a component technology program as part of the efforts to develop Stirling converter technology for space power applications. The Stirling Space Power Program is part of the NASA High Capacity Power Project of the Civil Space Technology Initiative (CSTI). NASA Lewis is also providing technical management for the DOE/Sandia program to develop Stirling converters for solar terrestrial power producing electricity for the utility grid. The primary contractors for the space power and solar terrestrial programs develop component technologies directly related to their goals. This Lewis component technology effort, while coordinated with the main programs, aims at longer term issues, advanced technologies, and independent assessments. An overview of work on linear alternators, engine/alternator/load interactions and controls, heat exchangers, materials, life and reliability, and bearings is presented.

  1. Component technology for Stirling power converters

    NASA Technical Reports Server (NTRS)

    Thieme, Lanny G.

    1991-01-01

    NASA Lewis Research Center has organized a component technology program as part of the efforts to develop Stirling converter technology for space power applications. The Stirling Space Power Program is part of the NASA High Capacity Power Project of the Civil Space Technology Initiative (CSTI). NASA Lewis is also providing technical management for the DOE/Sandia program to develop Stirling converters for solar terrestrial power producing electricity for the utility grid. The primary contractors for the space power and solar terrestrial programs develop component technologies directly related to their goals. This Lewis component technology effort, while coordinated with the main programs, aims at longer term issues, advanced technologies, and independent assessments. An overview of work on linear alternators, engine/alternator/load interactions and controls, heat exchangers, materials, life and reliability, and bearings is presented.

  2. Optical analog-to-digital converter

    DOEpatents

    Vawter, G. Allen; Raring, James; Skogen, Erik J.

    2009-07-21

    An optical analog-to-digital converter (ADC) is disclosed which converts an input optical analog signal to an output optical digital signal at a sampling rate defined by a sampling optical signal. Each bit of the digital representation is separately determined using an optical waveguide interferometer and an optical thresholding element. The interferometer uses the optical analog signal and the sampling optical signal to generate a sinusoidally-varying output signal using cross-phase-modulation (XPM) or a photocurrent generated from the optical analog signal. The sinusoidally-varying output signal is then digitized by the thresholding element, which includes a saturable absorber or at least one semiconductor optical amplifier, to form the optical digital signal which can be output either in parallel or serially.

  3. A high efficiency photovoltaic module integrated converter with the asymmetrical half-bridge flyback converter

    SciTech Connect

    Kim, Heeje; Kim, Jongrak; Shin, Dongsul; Kim, Hosung; Lee, Kyungjun; Kim, Jonghyun; Yoo, Dongwook

    2010-08-15

    A module integrated converter (MIC) for a photovoltaic (PV) cell is important part of power conditioning system (PCS). It performs maximum power point tracking of a PV cell to generate the power as much as possible from solar energy. There are several methods for connection between the PV modules and the MICs. In order to avoid partial shading effects, converter-per-module approach was proposed. The MIC that performs maximum power point tracking (MPPT), if it is low efficiency, is no use. The MIC whose output is connected to the output of PV module was proposed for high efficiency. However, there are some problems. In this study, an asymmetrical half-bridge flyback converter is proposed instead of the original flyback converter with same method to solve the problems. The proposed MIC was built to verify the performance. The new topology using soft switching technique showed good performance for the efficiency. At the higher power, the efficiency of the proposed converter is higher than existing converter. (author)

  4. (Convertible) Undeniable Signatures Without Random Oracles

    NASA Astrophysics Data System (ADS)

    Yuen, Tsz Hon; Au, Man Ho; Liu, Joseph K.; Susilo, Willy

    We propose a convertible undeniable signature scheme without random oracles. Our construction is based on Waters' and Kurosawa and Heng's schemes that were proposed in Eurocrypt 2005. The security of our scheme is based on the CDH and the decision linear assumption. Comparing only the part of undeniable signatures, our scheme uses more standard assumptions than the existing undeniable signatures without random oracles due to Laguillamie and Vergnaud.

  5. APPARATUS FOR CONVERTING HEAT INTO ELECTRICITY

    DOEpatents

    Crouthamel, C.E.; Foster, M.S.

    1964-01-28

    This patent shows an apparatus for converting heat to electricity. It includes a galvanic cell having an anodic metal anode, a fused salt electrolyte, and a hydrogen cathode having a diffusible metal barrier of silver-- palladium alloy covered with sputtered iron on the side next to the fused electrolyte. Also shown is a regenerator for regenerating metal hydride produced by the galvanic cell into hydrogen gas and anodic metal, both of which are recycled. (AEC)

  6. Fracture imaging with converted elastic waves

    SciTech Connect

    Nihei, K.T.; Nakagawa, S.; Myer, L.R.

    2001-05-29

    This paper examines the seismic signatures of discrete, finite-length fractures, and outlines an approach for elastic, prestack reverse-time imaging of discrete fractures. The results of this study highlight the importance of incorporating fracture-generated P-S converted waves into the imaging method, and presents an alternate imaging condition that can be used in elastic reverse-time imaging when a direct wave is recorded (e.g., for crosswell and VSP acquisition geometries).

  7. Thermionic converter performance with oxide collectors

    NASA Technical Reports Server (NTRS)

    Lieb, D.; Goodale, D.; Briere, T.; Balestra, C.

    1977-01-01

    Thermionic converters using a variety of metal oxide collector surfaces have been fabricated and tested. Both work function and power output data are presented and evaluated. Oxides of barium, strontium, zinc, tungsten and titanium have been incorporated into a variable spacing converter. Tungsten oxide was found to give the highest converter performance and to furnish oxygen for the emitter at the same time. Oxygenated emitters operate at reduced cesium pressure with an increase in electrode spacing. Electron spectroscopy for chemical analysis (ESCA) performed on several tungsten oxide collectors showed cesium penetration of the oxide layer, possibly forming a cesium tungstate bronze. Titanium oxide showed high performance but did not furnish oxygen for the emitter; strontium oxide, in the form of a sprayed layer, appeared to dissociate in the presence of cesium. Sprayed coatings of barium and zinc oxides produced collector work functions of about 1.3 eV, but had excessive series resistance. Lanthanum hexaboride, in combination with oxygen introduced through a silver tube, and cesium produced a low work function collector and better than average performance.

  8. Low temperature operation of a boost converter

    SciTech Connect

    Moss, B.S.; Boudreaux, R.R.; Nelms, R.M.

    1996-12-31

    The development of satellite power systems capable of operating at low temperatures on the order of 77K would reduce the heating system required on deep space vehicles. The power supplies in the satellite power system must be capable of operating at these temperatures. This paper presents the results of a study into the operation of a boost converter at temperatures close to 77K. The boost converter is designed to supply an output voltage and power of 42 V and 50 W from a 28 V input source. The entire system, except the 28 V source, is placed in the environmental chamber. This is important because the system does not require any manual adjustments to maintain a constant output voltage with a high efficiency. The constant 42 V output of this converter is a benefit of the application of a CMOS microcontroller in the feedback path. The switch duty cycle is adjusted by the microcontroller to maintain a constant output voltage. The efficiency of the system varied less than 1% over the temperature range of 22 C to {minus}184 C and was approximately 94.2% when the temperature was {minus}184 C.

  9. MOP /Matrix Operation Programs system/

    NASA Technical Reports Server (NTRS)

    Muller, P. M.

    1968-01-01

    MOP /Matrix Operation Programs/ system consists of a set of FORTRAN 4 subroutines which are related through a small common allocation. The system accomplishes all matrix algebra operations plus related input-output and housekeeping details.

  10. Matrix Theory of Small Oscillations

    ERIC Educational Resources Information Center

    Chavda, L. K.

    1978-01-01

    A complete matrix formulation of the theory of small oscillations is presented. Simple analytic solutions involving matrix functions are found which clearly exhibit the transients, the damping factors, the Breit-Wigner form for resonances, etc. (BB)

  11. A high speed CMOS A/D converter

    NASA Technical Reports Server (NTRS)

    Wiseman, Don R.; Whitaker, Sterling R.

    1992-01-01

    This paper presents a high speed analog-to-digital (A/D) converter. The converter is a 7 bit flash converter with one half LSB accuracy. Typical parts will function at approximately 200 MHz. The converter uses a novel comparator circuit that is shown to out perform more traditional comparators, and thus increases the speed of the converter. The comparator is a clocked, precharged circuit that offers very fast operation with a minimal offset voltage (2 mv). The converter was designed using a standard 1 micron digital CMOS process and is 2,244 microns by 3,972 microns.

  12. Converting Multi-Shell and Diffusion Spectrum Imaging to High Angular Resolution Diffusion Imaging.

    PubMed

    Yeh, Fang-Cheng; Verstynen, Timothy D

    2016-01-01

    Multi-shell and diffusion spectrum imaging (DSI) are becoming increasingly popular methods of acquiring diffusion MRI data in a research context. However, single-shell acquisitions, such as diffusion tensor imaging (DTI) and high angular resolution diffusion imaging (HARDI), still remain the most common acquisition schemes in practice. Here we tested whether multi-shell and DSI data have conversion flexibility to be interpolated into corresponding HARDI data. We acquired multi-shell and DSI data on both a phantom and in vivo human tissue and converted them to HARDI. The correlation and difference between their diffusion signals, anisotropy values, diffusivity measurements, fiber orientations, connectivity matrices, and network measures were examined. Our analysis result showed that the diffusion signals, anisotropy, diffusivity, and connectivity matrix of the HARDI converted from multi-shell and DSI were highly correlated with those of the HARDI acquired on the MR scanner, with correlation coefficients around 0.8~0.9. The average angular error between converted and original HARDI was 20.7° at voxels with signal-to-noise ratios greater than 5. The network topology measures had less than 2% difference, whereas the average nodal measures had a percentage difference around 4~7%. In general, multi-shell and DSI acquisitions can be converted to their corresponding single-shell HARDI with high fidelity. This supports multi-shell and DSI acquisitions over HARDI acquisition as the scheme of choice for diffusion acquisitions.

  13. Converting Multi-Shell and Diffusion Spectrum Imaging to High Angular Resolution Diffusion Imaging

    PubMed Central

    Yeh, Fang-Cheng; Verstynen, Timothy D.

    2016-01-01

    Multi-shell and diffusion spectrum imaging (DSI) are becoming increasingly popular methods of acquiring diffusion MRI data in a research context. However, single-shell acquisitions, such as diffusion tensor imaging (DTI) and high angular resolution diffusion imaging (HARDI), still remain the most common acquisition schemes in practice. Here we tested whether multi-shell and DSI data have conversion flexibility to be interpolated into corresponding HARDI data. We acquired multi-shell and DSI data on both a phantom and in vivo human tissue and converted them to HARDI. The correlation and difference between their diffusion signals, anisotropy values, diffusivity measurements, fiber orientations, connectivity matrices, and network measures were examined. Our analysis result showed that the diffusion signals, anisotropy, diffusivity, and connectivity matrix of the HARDI converted from multi-shell and DSI were highly correlated with those of the HARDI acquired on the MR scanner, with correlation coefficients around 0.8~0.9. The average angular error between converted and original HARDI was 20.7° at voxels with signal-to-noise ratios greater than 5. The network topology measures had less than 2% difference, whereas the average nodal measures had a percentage difference around 4~7%. In general, multi-shell and DSI acquisitions can be converted to their corresponding single-shell HARDI with high fidelity. This supports multi-shell and DSI acquisitions over HARDI acquisition as the scheme of choice for diffusion acquisitions. PMID:27683539

  14. Converting Multi-Shell and Diffusion Spectrum Imaging to High Angular Resolution Diffusion Imaging.

    PubMed

    Yeh, Fang-Cheng; Verstynen, Timothy D

    2016-01-01

    Multi-shell and diffusion spectrum imaging (DSI) are becoming increasingly popular methods of acquiring diffusion MRI data in a research context. However, single-shell acquisitions, such as diffusion tensor imaging (DTI) and high angular resolution diffusion imaging (HARDI), still remain the most common acquisition schemes in practice. Here we tested whether multi-shell and DSI data have conversion flexibility to be interpolated into corresponding HARDI data. We acquired multi-shell and DSI data on both a phantom and in vivo human tissue and converted them to HARDI. The correlation and difference between their diffusion signals, anisotropy values, diffusivity measurements, fiber orientations, connectivity matrices, and network measures were examined. Our analysis result showed that the diffusion signals, anisotropy, diffusivity, and connectivity matrix of the HARDI converted from multi-shell and DSI were highly correlated with those of the HARDI acquired on the MR scanner, with correlation coefficients around 0.8~0.9. The average angular error between converted and original HARDI was 20.7° at voxels with signal-to-noise ratios greater than 5. The network topology measures had less than 2% difference, whereas the average nodal measures had a percentage difference around 4~7%. In general, multi-shell and DSI acquisitions can be converted to their corresponding single-shell HARDI with high fidelity. This supports multi-shell and DSI acquisitions over HARDI acquisition as the scheme of choice for diffusion acquisitions. PMID:27683539

  15. Converting Multi-Shell and Diffusion Spectrum Imaging to High Angular Resolution Diffusion Imaging

    PubMed Central

    Yeh, Fang-Cheng; Verstynen, Timothy D.

    2016-01-01

    Multi-shell and diffusion spectrum imaging (DSI) are becoming increasingly popular methods of acquiring diffusion MRI data in a research context. However, single-shell acquisitions, such as diffusion tensor imaging (DTI) and high angular resolution diffusion imaging (HARDI), still remain the most common acquisition schemes in practice. Here we tested whether multi-shell and DSI data have conversion flexibility to be interpolated into corresponding HARDI data. We acquired multi-shell and DSI data on both a phantom and in vivo human tissue and converted them to HARDI. The correlation and difference between their diffusion signals, anisotropy values, diffusivity measurements, fiber orientations, connectivity matrices, and network measures were examined. Our analysis result showed that the diffusion signals, anisotropy, diffusivity, and connectivity matrix of the HARDI converted from multi-shell and DSI were highly correlated with those of the HARDI acquired on the MR scanner, with correlation coefficients around 0.8~0.9. The average angular error between converted and original HARDI was 20.7° at voxels with signal-to-noise ratios greater than 5. The network topology measures had less than 2% difference, whereas the average nodal measures had a percentage difference around 4~7%. In general, multi-shell and DSI acquisitions can be converted to their corresponding single-shell HARDI with high fidelity. This supports multi-shell and DSI acquisitions over HARDI acquisition as the scheme of choice for diffusion acquisitions.

  16. On the Matrix Exponential Function

    ERIC Educational Resources Information Center

    Hou, Shui-Hung; Hou, Edwin; Pang, Wan-Kai

    2006-01-01

    A novel and simple formula for computing the matrix exponential function is presented. Specifically, it can be used to derive explicit formulas for the matrix exponential of a general matrix A satisfying p(A) = 0 for a polynomial p(s). It is ready for use in a classroom and suitable for both hand as well as symbolic computation.

  17. The cellulose resource matrix.

    PubMed

    Keijsers, Edwin R P; Yılmaz, Gülden; van Dam, Jan E G

    2013-03-01

    The emerging biobased economy is causing shifts from mineral fossil oil based resources towards renewable resources. Because of market mechanisms, current and new industries utilising renewable commodities, will attempt to secure their supply of resources. Cellulose is among these commodities, where large scale competition can be expected and already is observed for the traditional industries such as the paper industry. Cellulose and lignocellulosic raw materials (like wood and non-wood fibre crops) are being utilised in many industrial sectors. Due to the initiated transition towards biobased economy, these raw materials are intensively investigated also for new applications such as 2nd generation biofuels and 'green' chemicals and materials production (Clark, 2007; Lange, 2007; Petrus & Noordermeer, 2006; Ragauskas et al., 2006; Regalbuto, 2009). As lignocellulosic raw materials are available in variable quantities and qualities, unnecessary competition can be avoided via the choice of suitable raw materials for a target application. For example, utilisation of cellulose as carbohydrate source for ethanol production (Kabir Kazi et al., 2010) avoids the discussed competition with easier digestible carbohydrates (sugars, starch) deprived from the food supply chain. Also for cellulose use as a biopolymer several different competing markets can be distinguished. It is clear that these applications and markets will be influenced by large volume shifts. The world will have to reckon with the increase of competition and feedstock shortage (land use/biodiversity) (van Dam, de Klerk-Engels, Struik, & Rabbinge, 2005). It is of interest - in the context of sustainable development of the bioeconomy - to categorize the already available and emerging lignocellulosic resources in a matrix structure. When composing such "cellulose resource matrix" attention should be given to the quality aspects as well as to the available quantities and practical possibilities of processing the

  18. The cellulose resource matrix.

    PubMed

    Keijsers, Edwin R P; Yılmaz, Gülden; van Dam, Jan E G

    2013-03-01

    The emerging biobased economy is causing shifts from mineral fossil oil based resources towards renewable resources. Because of market mechanisms, current and new industries utilising renewable commodities, will attempt to secure their supply of resources. Cellulose is among these commodities, where large scale competition can be expected and already is observed for the traditional industries such as the paper industry. Cellulose and lignocellulosic raw materials (like wood and non-wood fibre crops) are being utilised in many industrial sectors. Due to the initiated transition towards biobased economy, these raw materials are intensively investigated also for new applications such as 2nd generation biofuels and 'green' chemicals and materials production (Clark, 2007; Lange, 2007; Petrus & Noordermeer, 2006; Ragauskas et al., 2006; Regalbuto, 2009). As lignocellulosic raw materials are available in variable quantities and qualities, unnecessary competition can be avoided via the choice of suitable raw materials for a target application. For example, utilisation of cellulose as carbohydrate source for ethanol production (Kabir Kazi et al., 2010) avoids the discussed competition with easier digestible carbohydrates (sugars, starch) deprived from the food supply chain. Also for cellulose use as a biopolymer several different competing markets can be distinguished. It is clear that these applications and markets will be influenced by large volume shifts. The world will have to reckon with the increase of competition and feedstock shortage (land use/biodiversity) (van Dam, de Klerk-Engels, Struik, & Rabbinge, 2005). It is of interest - in the context of sustainable development of the bioeconomy - to categorize the already available and emerging lignocellulosic resources in a matrix structure. When composing such "cellulose resource matrix" attention should be given to the quality aspects as well as to the available quantities and practical possibilities of processing the

  19. Optimal laser wavelength for efficient laser power converter operation over temperature

    NASA Astrophysics Data System (ADS)

    Höhn, O.; Walker, A. W.; Bett, A. W.; Helmers, H.

    2016-06-01

    A temperature dependent modeling study is conducted on a GaAs laser power converter to identify the optimal incident laser wavelength for optical power transmission. Furthermore, the respective temperature dependent maximal conversion efficiencies in the radiative limit as well as in a practically achievable limit are presented. The model is based on the transfer matrix method coupled to a two-diode model, and is calibrated to experimental data of a GaAs photovoltaic device over laser irradiance and temperature. Since the laser wavelength does not strongly influence the open circuit voltage of the laser power converter, the optimal laser wavelength is determined to be in the range where the external quantum efficiency is maximal, but weighted by the photon flux of the laser.

  20. Why flavins are not competitors of chlorophyll in the evolution of biological converters of solar energy.

    PubMed

    Kritsky, Mikhail S; Telegina, Taisiya A; Vechtomova, Yulia L; Buglak, Andrey A

    2012-12-27

    Excited flavin molecules can photocatalyze reactions, leading to the accumulation of free energy in the products, and the data accumulated through biochemical experiments and by modeling prebiological processes suggest that flavins were available in the earliest stages of evolution. Furthermore, model experiments have shown that abiogenic flavin conjugated with a polyamino acid matrix, a pigment that photocatalyzes the phosphorylation of ADP to form ATP, could have been present in the prebiotic environment. Indeed, excited flavin molecules play key roles in many photoenzymes and regulatory photoreceptors, and the substantial structural differences between photoreceptor families indicate that evolution has repeatedly used flavins as chromophores for photoreceptor proteins. Some of these photoreceptors are equipped with a light-harvesting antenna, which transfers excitation energy to chemically reactive flavins in the reaction center. The sum of the available data suggests that evolution could have led to the formation of a flavin-based biological converter to convert light energy into energy in the form of ATP.

  1. On Hermite Matrix Polynomials of Two Variables

    NASA Astrophysics Data System (ADS)

    Kahmmash, Ghazi S.

    This study deals with the two-variable Hermite matrix polynomials, some relevant matrix functions appear interims of the two-variable Hermite matrix polynomials the relationships with Hermite matrix polynomials of one variable, Chepyshev matrix polynomials of the second kind have been obtained and expansion of the. Gegenbauer matrix polynomials as series of Hermite matrix polynomials.

  2. Supported Molecular Matrix Electrophoresis.

    PubMed

    Matsuno, Yu-Ki; Kameyama, Akihiko

    2015-01-01

    Mucins are difficult to separate using conventional gel electrophoresis methods such as SDS-PAGE and agarose gel electrophoresis, owing to their large size and heterogeneity. On the other hand, cellulose acetate membrane electrophoresis can separate these molecules, but is not compatible with glycan analysis. Here, we describe a novel membrane electrophoresis technique, termed "supported molecular matrix electrophoresis" (SMME), in which a porous polyvinylidene difluoride (PVDF) membrane filter is used to achieve separation. This description includes the separation, visualization, and glycan analysis of mucins with the SMME technique. PMID:26139278

  3. High power density dc/dc converter: Selection of converter topology

    NASA Technical Reports Server (NTRS)

    Divan, Deepakraj M.

    1990-01-01

    The work involved in the identification and selection of a suitable converter topology is described. Three new dc/dc converter topologies are proposed: Phase-Shifted Single Active Bridge DC/DC Converter; Single Phase Dual Active Bridges DC/DC Converter; and Three Phase Dual Active Bridges DC/DC Converter (Topology C). The salient features of these topologies are: (1) All are minimal in structure, i.e., each consists of an input and output bridge, input and output filter and a transformer, all components essential for a high power dc/dc conversion process; (2) All devices of both the bridges can operate under near zero-voltage conditions, making possible a reduction of device switching losses and hence, an increase in switching frequency; (3) All circuits operate at a constant frequency, thus simplifying the task of the magnetic and filter elements; (4) Since, the leakage inductance of the transformer is used as the main current transfer element, problems associated with the diode reverse recovery are eliminated. Also, this mode of operation allows easy paralleling of multiple modules for extending the power capacity of the system; (5) All circuits are least sensitive to parasitic impedances, infact the parasitics are efficently utilized; and (6) The soft switching transitions, result in low electromagnetic interference. A detailed analysis of each topology was carried out. Based on the analysis, the various device and component ratings for each topology operating at an optimum point, and under the given specifications, are tabulated and discussed.

  4. Gray & white matter tissue contrast differentiates Mild Cognitive Impairment converters from non-converters.

    PubMed

    Jefferson, Angela L; Gifford, Katherine A; Damon, Stephen; Chapman, G William; Liu, Dandan; Sparling, Jamie; Dobromyslin, Vitaly; Salat, David

    2015-06-01

    The clinical relevance of gray/white matter contrast ratio (GWR) in mild cognitive impairment (MCI) remains unknown. This study examined baseline GWR and 3-year follow-up diagnostic status in MCI. Alzheimer's Disease Neuroimaging Initiative MCI participants with baseline 1.5 T MRI and 3-year follow-up clinical data were included. Participants were categorized into two groups based on 3-year follow-up diagnoses: 1) non-converters (n = 69, 75 ± 7, 26 % female), and 2) converters (i.e., dementia at follow-up; n = 69, 75 ± 7, 30 % female) who were matched on baseline age and Mini-Mental State Examination scores. Groups were compared on FreeSurfer generated baseline GWR from structural images in which higher values represent greater tissue contrast. A general linear model, adjusting for APOE-status, scanner type, hippocampal volume, and cortical thickness, revealed that converters evidenced lower GWR values than non-converters (i.e., more degradation in tissue contrast; p = 0.03). Individuals with MCI who convert to dementia have lower baseline GWR values than individuals who remain diagnostically stable over a 3-year period, statistically independent of cortical thickness or hippocampal volume.

  5. 3. Rear (north) and east elevations of converted chicken house, ...

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

    3. Rear (north) and east elevations of converted chicken house, with smokehouse, cooling (well) house, and residence in background - Henry E. Williams Farmstead, Converted Chicken House, East of Residence & Smokehouse, Cedar Point, Chase County, KS

  6. Transformerless dc-to-dc converters with large conversion ratios

    NASA Astrophysics Data System (ADS)

    Middlebrook, R. D.

    1988-10-01

    A novel switching dc-dc converter is introduced in which large voltage step-down ratios can be achieved without a very small duty ratio and without a transformer. The circuit is an extension of the Cuk converter to incorporate a multistage capacitor divider. A particularly suitable application would be a 50-V to 5-V converter in which dc isolation is not required. The absence of a transformer and the larger duty ratio permit operation at a high switching frequency and make the circuit amenable to partial integration and hybrid construction techniques. An experimental 50-W three-stage voltage-divider Cuk converter converts 50 V to 5 V at 500 kHz, with efficiency higher than for a basic Cuk converter operated at the same conditions. A corresponding voltage-multiplier Cuk converter is described, as well as dual buck-boost-derived step-down and step-up converters.

  7. Voltage balanced multilevel voltage source converter system

    DOEpatents

    Peng, Fang Zheng; Lai, Jih-Sheng

    1997-01-01

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

  8. Voltage balanced multilevel voltage source converter system

    DOEpatents

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

    1997-07-01

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

  9. Text converter to support legislative process

    NASA Astrophysics Data System (ADS)

    Woźniak, Karol; Mulawka, Jan

    2013-10-01

    The aim of this paper is to design and implement software application converting text of law acts documents from Microsoft Word file format to structural form of law acts in XML format. The structure of XML documents is consistent with the legislative rules and standards which are defined in XML Schema provided by Polish parliamentary units. This approach encompasses the following steps: analysis of software requirements, presentation of problem solving concept, design and implementation directions of the final application. Certain experiments and software testing were performed in order to verify the correctness of the solution. A brief summary and some comments were demonstrated in the final conclusion.

  10. Converting VSAM in COBOL to embedded SQL

    SciTech Connect

    Huang, Hai; Wang, Yamin; Tsai, Wei-Tek

    1996-12-31

    VSAM databases we widely used on IBM mainframe systems. As new technology, such as relational database and client-server computing, becomes popular, there is a need to reengineer the VSAM databases to relational databases. This paper addresses the issues on converting COBOL programs that access VSAM database to COBOL programs that access relational databases with embedded SQL. It proposed a semi-automatic approach to the conversion of VSAM data sets to SQL tables and VSAM operations in COBOL program to embedded SQL queries. The proposed approach has been experimented on several industrial COBOL programs and a tool implementing the approach is under development.

  11. Converting information from paper to optical media

    NASA Technical Reports Server (NTRS)

    Deaton, Timothy N.; Tiller, Bruce K.

    1990-01-01

    The technology of converting large amounts of paper into electronic form is described for use in information management systems based on optical disk storage. The space savings and photographic nature of microfiche are combined in these systems with the advantages of computerized data (fast and flexible retrieval of graphics and text, simultaneous instant access for multiple users, and easy manipulation of data). It is noted that electronic imaging systems offer a unique opportunity to dramatically increase the productivity and profitability of information systems. Particular attention is given to the CALS (Computer-aided Aquisition and Logistic Support) system.

  12. A wideband 12 GHz down converter

    NASA Technical Reports Server (NTRS)

    Newman, B. A.; Rosenbaum, F. J.

    1972-01-01

    The design, fabrication, and evaluation of a single ended 12 GHz down-converter suitable for use in a low cost satellite ground terminal is described. The mixer uses waveguide, coaxial and MIC (microwave integrated circuit) transmission line components. Theoretical and experimental analyses of several microstrip circuit elements are presented including the traveling wave-directional filter, quarter wave-length proximity directional coupler, low pass filter and the quarterwave band stop filter. The optimum performance achieved for the mixer using a packaged diode was 9.4 db conversion loss and a bandwidth of 275 MHz.

  13. Solid state transport-based thermoelectric converter

    DOEpatents

    Hu, Zhiyu

    2010-04-13

    A solid state thermoelectric converter includes a thermally insulating separator layer, a semiconducting collector and an electron emitter. The electron emitter comprises a metal nanoparticle layer or plurality of metal nanocatalyst particles disposed on one side of said separator layer. A first electrically conductive lead is electrically coupled to the electron emitter. The collector layer is disposed on the other side of the separator layer, wherein the thickness of the separator layer is less than 1 .mu.m. A second conductive lead is electrically coupled to the collector layer.

  14. German Point Of Load Converter Initiative To Design A Pol Converter Demonstrator For Space Application

    NASA Astrophysics Data System (ADS)

    Heyer, Heinz-Volker; Scheytt, Christoph; Scholz, Stefan; Teply, Florian; Sorge, Roland; Hasan, Arif; Ma, Yan; Grau, Gunter

    2011-10-01

    In satellites supporting broadcast and remote sensing the number of digital users with new CMOS technologies and decreased supply voltages is growing. The low voltages in digital devices (FPGAs, processors etc.) lead to high currents in the supply lines with the drawback of high voltage dropouts in the supply lines and bad dynamic behavior. The solution is the use of so-called Point-of-Load converters (POL) directly at the digital load with radiation hardness characteristics. The mixed signal ASIC technology of IHP (SGB25V) with LDMOS option will be used for designing the new POL converter that provided acceptable results from radiation tests at ATLAS [1, 2]. Some key components needed for radiation hardness of this technology are designed by advICo and thus both design teams will work together under research contract of an efficient buck or step down converter for POL applications from German Space Agency (DLR).

  15. 31 CFR 800.206 - Convertible voting instrument.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 31 Money and Finance:Treasury 3 2011-07-01 2011-07-01 false Convertible voting instrument. 800.206..., AND TAKEOVERS BY FOREIGN PERSONS Definitions § 800.206 Convertible voting instrument. The term convertible voting instrument means a financial instrument that currently does not entitle its owner or...

  16. 40 CFR 90.319 - NOX converter check.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 20 2011-07-01 2011-07-01 false NOX converter check. 90.319 Section 90... Provisions § 90.319 NOX converter check. (a) The efficiency of the converter used for the conversion of NO2... procedure described in paragraphs (a)(2) through (a)(8) of this section, test the efficiency of...

  17. 40 CFR 89.317 - NOX converter check.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 20 2011-07-01 2011-07-01 false NOX converter check. 89.317 Section 89... Provisions § 89.317 NOX converter check. (a) Prior to its introduction into service, and monthly thereafter, the chemiluminescent oxides of nitrogen analyzer shall be checked for NO2 to NO converter...

  18. 12 CFR 708a.2 - Authority to convert.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 6 2010-01-01 2010-01-01 false Authority to convert. 708a.2 Section 708a.2... INSURED CREDIT UNIONS TO MUTUAL SAVINGS BANKS § 708a.2 Authority to convert. A credit union, with the approval of its members, may convert to a mutual savings bank or a savings association that is in...

  19. 40 CFR 91.319 - NOX converter check.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) CONTROL OF EMISSIONS FROM MARINE SPARK-IGNITION ENGINES Emission Test Equipment Provisions § 91.319 NOX converter check. (a) The efficiency of the converter used for the conversion of NO2 to NO is tested as given... efficiency of converters by means of an ozonator. (2) Calibrate the HCLD in the most common operating...

  20. Converting DYNAMO simulations to Powersim Studio simulations

    SciTech Connect

    Walker, La Tonya Nicole; Malczynski, Leonard A.

    2014-02-01

    DYNAMO is a computer program for building and running 'continuous' simulation models. It was developed by the Industrial Dynamics Group at the Massachusetts Institute of Technology for simulating dynamic feedback models of business, economic, and social systems. The history of the system dynamics method since 1957 includes many classic models built in DYANMO. It was not until the late 1980s that software was built to take advantage of the rise of personal computers and graphical user interfaces that DYNAMO was supplanted. There is much learning and insight to be gained from examining the DYANMO models and their accompanying research papers. We believe that it is a worthwhile exercise to convert DYNAMO models to more recent software packages. We have made an attempt to make it easier to turn these models into a more current system dynamics software language, Powersim © Studio produced by Powersim AS2 of Bergen, Norway. This guide shows how to convert DYNAMO syntax into Studio syntax.

  1. Resonant Tunneling Analog-To-Digital Converter

    NASA Technical Reports Server (NTRS)

    Broekaert, T. P. E.; Seabaugh, A. C.; Hellums, J.; Taddiken, A.; Tang, H.; Teng, J.; vanderWagt, J. P. A.

    1995-01-01

    As sampling rates continue to increase, current analog-to-digital converter (ADC) device technologies will soon reach a practical resolution limit. This limit will most profoundly effect satellite and military systems used, for example, for electronic countermeasures, electronic and signal intelligence, and phased array radar. New device and circuit concepts will be essential for continued progress. We describe a novel, folded architecture ADC which could enable a technological discontinuity in ADC performance. The converter technology is based on the integration of multiple resonant tunneling diodes (RTD) and hetero-junction transistors on an indium phosphide substrate. The RTD consists of a layered semiconductor hetero-structure AlAs/InGaAs/AlAs(2/4/2 nm) clad on either side by heavily doped InGaAs contact layers. Compact quantizers based around the RTD offer a reduction in the number of components and a reduction in the input capacitance Because the component count and capacitance scale with the number of bits N, rather than by 2 (exp n) as in the flash ADC, speed can be significantly increased, A 4-bit 2-GSps quantizer circuit is under development to evaluate the performance potential. Circuit designs for ADC conversion with a resolution of 6-bits at 25GSps may be enabled by the resonant tunneling approach.

  2. Forback DC-to-DC converter

    NASA Astrophysics Data System (ADS)

    Lukemire, Alan T.

    1993-03-01

    A pulse-width modulated DC-to-DC power converter including a first inductor, i.e. a transformer or an equivalent fixed inductor equal to the inductance of the secondary winding of the transformer, coupled across a source of DC input voltage via a transistor switch which is rendered alternately conductive (ON) and nonconductive (OFF) in accordance with a signal from a feedback control circuit is described. A first capacitor capacitively couples one side of the first inductor to a second inductor which is connected to a second capacitor which is coupled to the other side of the first inductor. A circuit load shunts the second capacitor. A semiconductor diode is additionally coupled from a common circuit connection between the first capacitor and the second inductor to the other side of the first inductor. A current sense transformer generating a current feedback signal for the switch control circuit is directly coupled in series with the other side of the first inductor so that the first capacitor, the second inductor and the current sense transformer are connected in series through the first inductor. The inductance values of the first and second inductors, moreover, are made identical. Such a converter topology results in a simultaneous voltsecond balance in the first inductance and ampere-second balance in the current sense transformer.

  3. Forback DC-to-DC converter

    NASA Astrophysics Data System (ADS)

    Lukemire, Alan T.

    1995-05-01

    A pulse-width modulated DC-to-DC power converter including a first inductor, i.e. a transformer or an equivalent fixed inductor equal to the inductance of the secondary winding of the transformer, coupled across a source of DC input voltage via a transistor switch which is rendered alternately conductive (ON) and nonconductive (OFF) in accordance with a signal from a feedback control circuit is described. A first capacitor capacitively couples one side of the first inductor to a second inductor which is connected to a second capacitor which is coupled to the other side of the first inductor. A circuit load shunts the second capacitor. A semiconductor diode is additionally coupled from a common circuit connection between the first capacitor and the second inductor to the other side of the first inductor. A current sense transformer generating a current feedback signal for the switch control circuit is directly coupled in series with the other side of the first inductor so that the first capacitor, the second inductor and the current sense transformer are connected in series through the first inductor. The inductance values of the first and second inductors, moreover, are made identical. Such a converter topology results in a simultaneous voltsecond balance in the first inductance and ampere-second balance in the current sense transformer.

  4. Angiotensin converting enzyme 2 and atherosclerosis.

    PubMed

    Wang, Yutang; Tikellis, Chris; Thomas, Merlin C; Golledge, Jonathan

    2013-01-01

    Angiotensin converting enzyme 2 (ACE2) is a homolog of angiotensin converting enzyme (ACE) which generates angiotensin II from angiotensin I. ACE, its product angiotensin II and the downstream angiotensin type I receptor are important components of the renin-angiotensin system (RAS). Angiotensin II, the most important component of the RAS, promotes the development of atherosclerosis. The identification of ACE2 in 2000 opened a new chapter of research on the regulation of the RAS. ACE2 degrades pro-atherosclerotic angiotensin II and generates anti-atherosclerotic angiotensin 1-7. In this review, we explored the importance of ACE2 in protecting experimental animals from developing atherosclerosis and its involvement in human atherosclerosis. We also examined the published evidence assessing the importance of ACE2 in different cell types relevant to atherosclerosis and putative underlying cellular and molecular mechanisms linking ACE2 with protection from atherosclerosis. ACE2 shifts the balance from angiotensin II to angiotensin 1-7 inhibiting the progression of atherosclerosis in animal models.

  5. Forback DC-to-DC converter

    NASA Technical Reports Server (NTRS)

    Lukemire, Alan T. (Inventor)

    1995-01-01

    A pulse-width modulated DC-to-DC power converter including a first inductor, i.e. a transformer or an equivalent fixed inductor equal to the inductance of the secondary winding of the transformer, coupled across a source of DC input voltage via a transistor switch which is rendered alternately conductive (ON) and nonconductive (OFF) in accordance with a signal from a feedback control circuit is described. A first capacitor capacitively couples one side of the first inductor to a second inductor which is connected to a second capacitor which is coupled to the other side of the first inductor. A circuit load shunts the second capacitor. A semiconductor diode is additionally coupled from a common circuit connection between the first capacitor and the second inductor to the other side of the first inductor. A current sense transformer generating a current feedback signal for the switch control circuit is directly coupled in series with the other side of the first inductor so that the first capacitor, the second inductor and the current sense transformer are connected in series through the first inductor. The inductance values of the first and second inductors, moreover, are made identical. Such a converter topology results in a simultaneous voltsecond balance in the first inductance and ampere-second balance in the current sense transformer.

  6. Converting CSV Files to RKSML Files

    NASA Technical Reports Server (NTRS)

    Trebi-Ollennu, Ashitey; Liebersbach, Robert

    2009-01-01

    A computer program converts, into a format suitable for processing on Earth, files of downlinked telemetric data pertaining to the operation of the Instrument Deployment Device (IDD), which is a robot arm on either of the Mars Explorer Rovers (MERs). The raw downlinked data files are in comma-separated- value (CSV) format. The present program converts the files into Rover Kinematics State Markup Language (RKSML), which is an Extensible Markup Language (XML) format that facilitates representation of operations of the IDD and enables analysis of the operations by means of the Rover Sequencing Validation Program (RSVP), which is used to build sequences of commanded operations for the MERs. After conversion by means of the present program, the downlinked data can be processed by RSVP, enabling the MER downlink operations team to play back the actual IDD activity represented by the telemetric data against the planned IDD activity. Thus, the present program enhances the diagnosis of anomalies that manifest themselves as differences between actual and planned IDD activities.

  7. Ultraviolet converter transients induced by electrons

    NASA Technical Reports Server (NTRS)

    Kernell, R. L.; Becher, J.; Reft, C. S.

    1984-01-01

    The output of ultraviolet converters typically used in satellite astronomy was monitored during irradiation with electrons from a sealed SR-90 source which approximated the peak flux in earth's outer electron belt. The signal induced by irradiation was attributed to two mechanisms: (1) photoelectrons resulting from photons created in the MgF2 window and (2) the direct impact of electrons on the phosphor. For irradiation at about 1 x 10 to the 7th e/sq cm sec, these two effects produced signals which were, in order of magnitude, the same as those produced by an incident UV flux (254 nm) of 10 to the 8th and 10 to the 7th photons/sq cm sec, respectively. In addition, the induced signal was investigated as a function of electron energy by irradiating another converter with 0.4-1.8-MeV electrons from a Van de Graaff. These results suggest that the dominant contribution to the electron-induced signal is Cerenkov photon production in the MgF2 window.

  8. Serial Pixel Analog-to-Digital Converter

    SciTech Connect

    Larson, E D

    2010-02-01

    This method reduces the data path from the counter to the pixel register of the analog-to-digital converter (ADC) from as many as 10 bits to a single bit. The reduction in data path width is accomplished by using a coded serial data stream similar to a pseudo random number (PRN) generator. The resulting encoded pixel data is then decoded into a standard hexadecimal format before storage. The high-speed serial pixel ADC concept is based on the single-slope integrating pixel ADC architecture. Previous work has described a massively parallel pixel readout of a similar architecture. The serial ADC connection is similar to the state-of-the art method with the exception that the pixel ADC register is a shift register and the data path is a single bit. A state-of-the-art individual-pixel ADC uses a single-slope charge integration converter architecture with integral registers and “one-hot” counters. This implies that parallel data bits are routed among the counter and the individual on-chip pixel ADC registers. The data path bit-width to the pixel is therefore equivalent to the pixel ADC bit resolution.

  9. Analysis of the polarization rotation effect in the inversely tapered spot size converter.

    PubMed

    Jia, Lianxi; Zhou, Haifeng; Liow, Tsung-Yang; Song, Junfeng; Huang, Ying; Tu, Xiaoguang; Luo, Xianshu; Li, Chao; Fang, Qing; Yu, Mingbin; Lo, Guoqiang

    2015-10-19

    Inversely tapered spot size converter (SSC) is widely used to connect silicon waveguide with fiber in silicon photonics. However, the tapered structure may cause polarization rotation and further generate interference fluctuation in the transmission spectrum even of a straight waveguide. We analyzed the light propagation in a straight waveguide with SSC at the both ends with coupling matrix and transmission matrix methods. The analysis results matched with the phenomena we observed in the transmission spectrum. Combining the analysis with the measurement results, we calculated the polarization rotation efficiency of the SSC in different samples and analyzed the origin of the polarization rotation effect. Finally, we discussed the influence of the effect to the DP-QPSK signal and proposed several methods to release the impact.

  10. Ceramic matrix and resin matrix composites: A comparison

    NASA Technical Reports Server (NTRS)

    Hurwitz, Frances I.

    1987-01-01

    The underlying theory of continuous fiber reinforcement of ceramic matrix and resin matrix composites, their fabrication, microstructure, physical and mechanical properties are contrasted. The growing use of organometallic polymers as precursors to ceramic matrices is discussed as a means of providing low temperature processing capability without the fiber degradation encountered with more conventional ceramic processing techniques. Examples of ceramic matrix composites derived from particulate-filled, high char yield polymers and silsesquioxane precursors are provided.

  11. Matrix membranes and integrability

    SciTech Connect

    Zachos, C.; Fairlie, D.; Curtright, T.

    1997-06-01

    This is a pedagogical digest of results reported in Curtright, Fairlie, {ampersand} Zachos 1997, and an explicit implementation of Euler`s construction for the solution of the Poisson Bracket dual Nahm equation. But it does not cover 9 and 10-dimensional systems, and subsequent progress on them Fairlie 1997. Cubic interactions are considered in 3 and 7 space dimensions, respectively, for bosonic membranes in Poisson Bracket form. Their symmetries and vacuum configurations are explored. Their associated first order equations are transformed to Nahm`s equations, and are hence seen to be integrable, for the 3-dimensional case, by virtue of the explicit Lax pair provided. Most constructions introduced also apply to matrix commutator or Moyal Bracket analogs.

  12. Mixed Mode Matrix Multiplication

    SciTech Connect

    Meng-Shiou Wu; Srinivas Aluru; Ricky A. Kendall

    2004-09-30

    In modern clustering environments where the memory hierarchy has many layers (distributed memory, shared memory layer, cache,...), an important question is how to fully utilize all available resources and identify the most dominant layer in certain computations. When combining algorithms on all layers together, what would be the best method to get the best performance out of all the resources we have? Mixed mode programming model that uses thread programming on the shared memory layer and message passing programming on the distributed memory layer is a method that many researchers are using to utilize the memory resources. In this paper, they take an algorithmic approach that uses matrix multiplication as a tool to show how cache algorithms affect the performance of both shared memory and distributed memory algorithms. They show that with good underlying cache algorithm, overall performance is stable. When underlying cache algorithm is bad, superlinear speedup may occur, and an increasing number of threads may also improve performance.

  13. Light cone matrix product

    SciTech Connect

    Hastings, Matthew B

    2009-01-01

    We show how to combine the light-cone and matrix product algorithms to simulate quantum systems far from equilibrium for long times. For the case of the XXZ spin chain at {Delta} = 0.5, we simulate to a time of {approx} 22.5. While part of the long simulation time is due to the use of the light-cone method, we also describe a modification of the infinite time-evolving bond decimation algorithm with improved numerical stability, and we describe how to incorporate symmetry into this algorithm. While statistical sampling error means that we are not yet able to make a definite statement, the behavior of the simulation at long times indicates the appearance of either 'revivals' in the order parameter as predicted by Hastings and Levitov (e-print arXiv:0806.4283) or of a distinct shoulder in the decay of the order parameter.

  14. A nanoscale linear-to-linear motion converter of graphene.

    PubMed

    Dai, Chunchun; Guo, Zhengrong; Zhang, Hongwei; Chang, Tienchong

    2016-08-14

    Motion conversion plays an irreplaceable role in a variety of machinery. Although many macroscopic motion converters have been widely used, it remains a challenge to convert motion at the nanoscale. Here we propose a nanoscale linear-to-linear motion converter, made of a flake-substrate system of graphene, which can convert the out-of-plane motion of the substrate into the in-plane motion of the flake. The curvature gradient induced van der Waals potential gradient between the flake and the substrate provides the driving force to achieve motion conversion. The proposed motion converter may have general implications for the design of nanomachinery and nanosensors.

  15. Bifurcation behaviours of peak current controlled PFC boost converter

    NASA Astrophysics Data System (ADS)

    Ren, Hai-Peng; Liu, Ding

    2005-07-01

    Bifurcation behaviours of the peak current controlled power-factor-correction (PFC) boost converter, including fast-scale instability and low-frequency bifurcation, are investigated in this paper. Conventionally, the PFC converter is analysed in continuous conduction mode (CCM). This prevents us from recognizing the overall dynamics of the converter. It has been pointed out that the discontinuous conduction mode (DCM) can occur in the PFC boost converter, especially in the light load condition. Therefore, the DCM model is employed to analyse the PFC converter to cover the possible DCM operation. By this way, the low-frequency bifurcation diagram is derived, which makes the route from period-double bifurcation to chaos clear. The bifurcation diagrams versus the load resistance and the output capacitance also indicate the stable operation boundary of the converter, which is useful for converter design.

  16. Homolumo gap and matrix model

    SciTech Connect

    Andric, I.; Jonke, L.; Jurman, D.; Nielsen, H. B.

    2008-06-15

    We discuss a dynamical matrix model by which probability distribution is associated with Gaussian ensembles from random matrix theory. We interpret the matrix M as a Hamiltonian representing interaction of a bosonic system with a single fermion. We show that a system of second-quantized fermions influences the ground state of the whole system by producing a gap between the highest occupied eigenvalue and the lowest unoccupied eigenvalue.

  17. Process of producing a ceramic matrix composite article and article formed thereby

    DOEpatents

    Corman, Gregory Scot; McGuigan, Henry Charles; Brun, Milivoj Konstantin

    2010-05-04

    A CMC article and process for producing the article to have a layer on its surface that protects a reinforcement material within the article from damage. The method entails providing a body containing a ceramic reinforcement material in a matrix material that contains a precursor of a ceramic matrix material. A fraction of the reinforcement material is present and possibly exposed at a surface of the body. The body surface is then provided with a surface layer formed of a slurry containing a particulate material but lacking the reinforcement material of the body. The body and surface layer are heated to form the article by converting the precursor within the body to form the ceramic matrix material in which the reinforcement material is contained, and by converting the surface layer to form the protective layer that covers any fraction of the reinforcement material exposed at the body surface.

  18. Process of producing a ceramic matrix composite article and article formed thereby

    DOEpatents

    Corman, Gregory Scot; McGuigan, Henry Charles; Brun, Milivoj Konstantin

    2011-10-25

    A CMC article and process for producing the article to have a layer on its surface that protects a reinforcement material within the article from damage. The method entails providing a body containing a ceramic reinforcement material in a matrix material that contains a precursor of a ceramic matrix material. A fraction of the reinforcement material is present and possibly exposed at a surface of the body. The body surface is then provided with a surface layer formed of a slurry containing a particulate material but lacking the reinforcement material of the body. The body and surface layer are heated to form the article by converting the precursor within the body to form the ceramic matrix material in which the reinforcement material is contained, and by converting the surface layer to form the protective layer that covers any fraction of the reinforcement material exposed at the body surface.

  19. A matrix model for WZW

    NASA Astrophysics Data System (ADS)

    Dorey, Nick; Tong, David; Turner, Carl

    2016-08-01

    We study a U( N) gauged matrix quantum mechanics which, in the large N limit, is closely related to the chiral WZW conformal field theory. This manifests itself in two ways. First, we construct the left-moving Kac-Moody algebra from matrix degrees of freedom. Secondly, we compute the partition function of the matrix model in terms of Schur and Kostka polynomials and show that, in the large N limit, it coincides with the partition function of the WZW model. This same matrix model was recently shown to describe non-Abelian quantum Hall states and the relationship to the WZW model can be understood in this framework.

  20. User's Manual for PCSMS (Parallel Complex Sparse Matrix Solver). Version 1.

    NASA Technical Reports Server (NTRS)

    Reddy, C. J.

    2000-01-01

    PCSMS (Parallel Complex Sparse Matrix Solver) is a computer code written to make use of the existing real sparse direct solvers to solve complex, sparse matrix linear equations. PCSMS converts complex matrices into real matrices and use real, sparse direct matrix solvers to factor and solve the real matrices. The solution vector is reconverted to complex numbers. Though, this utility is written for Silicon Graphics (SGI) real sparse matrix solution routines, it is general in nature and can be easily modified to work with any real sparse matrix solver. The User's Manual is written to make the user acquainted with the installation and operation of the code. Driver routines are given to aid the users to integrate PCSMS routines in their own codes.

  1. DC-to-DC switching converter

    NASA Technical Reports Server (NTRS)

    Cuk, Slobodan M. (Inventor); Middlebrook, Robert D. (Inventor)

    1980-01-01

    A dc-to-dc converter having nonpulsating input and output current uses two inductances, one in series with the input source, the other in series with the output load. An electrical energy transferring device with storage, namely storage capacitance, is used with suitable switching means between the inductances to DC level conversion. For isolation between the source and load, the capacitance may be divided into two capacitors coupled by a transformer, and for reducing ripple, the inductances may be coupled. With proper design of the coupling between the inductances, the current ripple can be reduced to zero at either the input or the output, or the reduction achievable in that way may be divided between the input and output.

  2. Static Frequency Converter System Installed and Tested

    NASA Technical Reports Server (NTRS)

    Brown, Donald P.; Sadhukhan, Debashis

    2003-01-01

    A new Static Frequency Converter (SFC) system has been installed and tested at the NASA Glenn Research Center s Central Air Equipment Building to provide consistent, reduced motor start times and improved reliability for the building s 14 large exhausters and compressors. The operational start times have been consistent around 2 min, 20 s per machine. This is at least a 3-min improvement (per machine) over the old variable-frequency motor generator sets. The SFC was designed and built by Asea Brown Boveri (ABB) and installed by Encompass Design Group (EDG) as part of a Construction of Facilities project managed by Glenn (Robert Scheidegger, project manager). The authors designed the Central Process Distributed Control Systems interface and control between the programmable logic controller, solid-state exciter, and switchgear, which was constructed by Gilcrest Electric.

  3. Modular Power Converters for PV Applications

    SciTech Connect

    Ozpineci, Burak; Tolbert, Leon M

    2012-05-01

    This report describes technical opportunities to serve as parts of a technological roadmap for Shoals Technologies Group in power electronics for PV applications. There are many different power converter circuits that can be used for solar inverter applications. The present applications do not take advantage of the potential for using common modules. We envision that the development of a power electronics module could enable higher reliability by being durable and flexible. Modules would have fault current limiting features and detection circuits such that they can limit the current through the module from external faults and can identify and isolate internal faults such that the remaining modules can continue to operate with only minimal disturbance to the utility or customer. Development of a reliable, efficient, low-cost, power electronics module will be a key enabling technology for harnessing more power from solar panels and enable plug and play operation. Power electronics for computer power supplies, communication equipment, and transportation have all targeted reliability and modularity as key requirements and have begun concerted efforts to replace monolithic components with collections of common smart modules. This is happening on several levels including (1) device level with intelligent control, (2) functional module level, and (3) system module. This same effort is needed in power electronics for solar applications. Development of modular units will result in standard power electronic converters that will have a lower installed and operating cost for the overall system. These units will lead to increased adaptability and flexibility of solar inverters. Incorporating autonomous fault current limiting and reconfiguration capabilities into the modules and having redundant modules will lead to a durable converter that can withstand the rigors of solar power generation for more than 30 years. Our vision for the technology roadmap is that there is no need

  4. A 60 channel PCM-ADPCM converter

    NASA Astrophysics Data System (ADS)

    Raulin, J.-M.; Bonnerot, G.; Jeandot, J.-L.; Lacroix, R.

    1982-04-01

    Coding techniques based on adaptive linear prediction and quantization are well suited to signals carried by telephone channels and can provide, with a per channel rate of 32 kbits/s, a level of quality compatible with the specifications of the conventional 64 kbit/s rate. The ADPCM technique described in this paper features a simple adaptive quantization scheme and a tenth-order linear prediction adaptive filter realized as a cascade of five second-order sections. Besides superior performance characteristics, the nonaccumulation of degradations in tandem connections is achieved. The implementation is a 60 channel PCM-ADPCM converter, called TMN 162. It is a fully digital equipment which offers a doubling of the capacity of digital links in telephone networks.

  5. A system for converting print into braille.

    PubMed

    Blenkhorn, P

    1997-06-01

    This paper describes a method for converting text into braille, in the form in which it is stored as in a computer. The system has been designed to be configurable for a wide range of languages and character sets, and uses a predominantly table driven method to achieve this. The algorithm is explained in the context of the conversion of text into Standard English Braille (British), and the tables for this transformation are given. Particular importance has been attached to enabling braille specialists, who are not experts in computer algorithms, to be able to modify the system for either slight modifications to an existing braille code translator, or for producing a braille code translator for a new language.

  6. Converting simple vegetation surveys in functional dynamics

    NASA Astrophysics Data System (ADS)

    Fernandes, Claúdia; Cabral, João Alexandre; Crespí, António Luís; Hughes, Samantha Jane; Santos, Mário

    2013-04-01

    This study assessed an integrated method for estimating the structural and functional trends of Mediterranean vegetation based on simple field characterizations. Despite considerable effort made by scientists to estimate vegetation dynamics, most methods are too complex to be applied and quantification achieved by non-specialists. We propose an alternative approach that converts simple measures such as generic vegetation cover into life forms or life traits. We used the Stochastic Dynamic Methodology, a dynamic approach based on a sequential process, to calculate the functional response to succession and anthropogenic disturbances using Raunkiaer's life form spectra. Using derived scenarios, the model was able to successfully translate functional and structural trends from simple field descriptions. The simulations demonstrate that this methodology can be used in environmental studies, particularly when specialised field botanists are not available.

  7. Angiotensin converting enzyme inhibition and the kidney

    NASA Technical Reports Server (NTRS)

    Hollenberg, N. K.

    1988-01-01

    Angiotensin II (Ang II) induces a marked reduction in renal blood flow at doses well below those required to induce a pressor response, and as blood flow falls there is a decline in glomerular filtration rate and sodium excretion. This striking sensitivity of the renal blood supply led many workers to consider the possibility that angiotensin functions as a local renal hormone. As angiotensin converting enzyme (ACE) was found in particular abundance in the lung, it seemed reasonable to suspect that most of the conversion occurred there, and that the function of Ang II would be primarily systemic, rather than intrarenal. In this review, I will explore the evidence that has accumulated on these two possibilities, since they have important implications for our current understanding of normal kidney function and derangements of kidney function in disease.

  8. Clustering of cycloidal wave energy converters

    DOEpatents

    Siegel, Stefan G.

    2016-03-29

    A wave energy conversion system uses a pair of wave energy converters (WECs) on respective active mountings on a floating platform, so that the separation of the WECs from each other or from a central WEC can be actively adjusted according to the wavelength of incident waves. The adjustable separation facilitates operation of the system to cancel reactive forces, which may be generated during wave energy conversion. Modules on which such pairs of WECs are mounted can be assembled with one or more central WECs to form large clusters in which reactive forces and torques can be made to cancel. WECs of different sizes can be employed to facilitate cancelation of reactive forces and torques.

  9. Mechanical vibration to electrical energy converter

    DOEpatents

    Kellogg, Rick Allen; Brotz, Jay Kristoffer

    2009-03-03

    Electromechanical devices that generate an electrical signal in response to an external source of mechanical vibrations can operate as a sensor of vibrations and as an energy harvester for converting mechanical vibration to electrical energy. The devices incorporate a magnet that is movable through a gap in a ferromagnetic circuit, wherein a coil is wound around a portion of the ferromagnetic circuit. A flexible coupling is used to attach the magnet to a frame for providing alignment of the magnet as it moves or oscillates through the gap in the ferromagnetic circuit. The motion of the magnet can be constrained to occur within a substantially linear range of magnetostatic force that develops due to the motion of the magnet. The devices can have ferromagnetic circuits with multiple arms, an array of magnets having alternating polarity and, encompass micro-electromechanical (MEM) devices.

  10. Radiant energy to electric energy converter

    NASA Technical Reports Server (NTRS)

    Sher, Arden (Inventor)

    1980-01-01

    Radiant energy is converted into electric energy by irradiating a capacitor including an ionic dielectric. The dielectric is a sintered crystal superionic conductor, e.g., lanthanum trifluoride, lanthanum trichloride, or silver bromide, so that a multiplicity of crystallites exist between electrodes of the capacitor. The radiant energy cyclically irradiates the dielectric so that the dielectric exhibits a cyclic photocapacitive like effect. Adjacent crystallites have abutting surfaces that enable the crystallites to effectively form a multiplicity of series capacitor elements between the electrodes. Each of the capacitor elements has a dipole layer only on or near its surface. The capacitor is initially charged to a voltage just below the dielectric breakdown voltage by connecting it across a DC source causing a current to flow through a charging resistor to the dielectric. The device can be utilized as a radiant energy detector or as a solar energy cell.

  11. Hybrid-free Josephson Parametric Converter

    NASA Astrophysics Data System (ADS)

    Frattini, N. E.; Narla, A.; Sliwa, K. M.; Shankar, S.; Hatridge, M.; Devoret, M. H.

    A necessary component for any quantum computation architecture is the ability to perform efficient quantum operations. In the microwave regime of superconducting qubits, these quantum-limited operations can be realized with a non-degenerate Josephson junction based three-wave mixer, the Josephson Parametric Converter (JPC). Currently, the quantum signal of interest must pass through a lossy 180 degree hybrid to be presented as a differential drive to the JPC. This hybrid therefore places a limit on the quantum efficiency of the system and also increases the device footprint. We present a new design for the JPC eliminating the need for any external hybrid. We also show that this design has nominally identical performance to the conventional JPC. Work supported by ARO, AFOSR and YINQE.

  12. Simplifying the circuit of Josephson parametric converters

    NASA Astrophysics Data System (ADS)

    Abdo, Baleegh; Brink, Markus; Chavez-Garcia, Jose; Keefe, George

    Josephson parametric converters (JPCs) are quantum-limited three-wave mixing devices that can play various important roles in quantum information processing in the microwave domain, including amplification of quantum signals, transduction of quantum information, remote entanglement of qubits, nonreciprocal amplification, and circulation of signals. However, the input-output and biasing circuit of a state-of-the-art JPC consists of bulky components, i.e. two commercial off-chip broadband 180-degree hybrids, four phase-matched short coax cables, and one superconducting magnetic coil. Such bulky hardware significantly hinders the integration of JPCs in scalable quantum computing architectures. In my talk, I will present ideas on how to simplify the JPC circuit and show preliminary experimental results

  13. Transcutaneous optical power converter for implantable devices

    NASA Astrophysics Data System (ADS)

    Tamura, Toshiyo; Shamsuddin, A. K. M.; Kawarada, Atsushi; Togawa, Tatsuo; Oberg, P. Ake

    1994-02-01

    An optical transcutaneous power converter has been developed for the power supply of implanted devices. It consists of a light source, optical fiber system and a photo detector. The light source is either a halogen lamp or continuous high-power laser diode which illuminated skin surface. The light penetrates through the skin to the solar cells. The preliminary experiments with a slice of tissue in between the light source and the solar cells showed that the power transfer efficiency was 40% in comparison to direct illumination of the solar cells. The maximum electric power obtained with a slice of tissue simulating the skin was about 8 mW at a laser diode run at a power of 100 mW. The electric power transferred is enough to supply low power consuming CMOS circuits.

  14. Converting a fuel to combustible gas

    SciTech Connect

    Moss, G.

    1985-04-02

    A sulfur-containing fuel is passed into a first fluidized bed containing CaSO/sub 4/ and CaO and an oxygen-transfer mediator (e.g. H/sub 2/) whereby the fuel is converted to combustible gas, some CaSO/sub 4/ being reduced to CaS and sulfur being fixed as CaS by reaction with CaO. Bed particles pass from the bottom layer of the first bed into the bottom layer of the second bed which is fluidized by air at conditions such that some, but not all of the CaS is selectively oxidized to CaSO/sub 4/ with no liberation of sulfur moieties. Bed particles pass from the bottom layer of second bed to the bottom layer of a third bed optionally after passage via a fourth bed between the second and third beds. In the third bed particles are fluidized with air to convert CaS selectively to CaSO/sub 4/ with no liberation of sulfur moiety whereby to raise the particles' temperature sufficiently above that of the first bed that particles passing from the bottom layer of the third bed into the bottom layer of the first bed provide sufficient sensible heat to maintain the fuel conversion temperature of the first bed. In the fourth bed particles are fluidized with air under such conditions that sulfur moiety is liberated, preferably at a rate which approximately equals the rate of sulfur-capture in the first bed whereby to maintain approximately a constant amount of reactive CaO in the beds for sulfur-capture in the first bed.

  15. Partially converted stereoscopic images and the effects on visual attention and memory

    NASA Astrophysics Data System (ADS)

    Kim, Sanghyun; Morikawa, Hiroyuki; Mitsuya, Reiko; Kawai, Takashi; Watanabe, Katsumi

    2015-03-01

    This study contained two experimental examinations of the cognitive activities such as visual attention and memory in viewing stereoscopic (3D) images. For this study, partially converted 3D images were used with binocular parallax added to a specific region of the image. In Experiment 1, change blindness was used as a presented stimulus. The visual attention and impact on memory were investigated by measuring the response time to accomplish the given task. In the change blindness task, an 80 ms blank was intersected between the original and altered images, and the two images were presented alternatingly for 240 ms each. Subjects were asked to temporarily memorize the two switching images and to compare them, visually recognizing the difference between the two. The stimuli for four conditions (2D, 3D, Partially converted 3D, distracted partially converted 3D) were randomly displayed for 20 subjects. The results of Experiment 1 showed that partially converted 3D images tend to attract visual attention and are prone to remain in viewer's memory in the area where moderate negative parallax has been added. In order to examine the impact of a dynamic binocular disparity on partially converted 3D images, an evaluation experiment was conducted that applied learning, distraction, and recognition tasks for 33 subjects. The learning task involved memorizing the location of cells in a 5 × 5 matrix pattern using two different colors. Two cells were positioned with alternating colors, and one of the gray cells was moved up, down, left, or right by one cell width. Experimental conditions was set as a partially converted 3D condition in which a gray cell moved diagonally for a certain period of time with a dynamic binocular disparity added, a 3D condition in which binocular disparity was added to all gray cells, and a 2D condition. The correct response rates for recognition of each task after the distraction task were compared. The results of Experiment 2 showed that the correct

  16. Matrix market: a web resource for test matrix collection

    SciTech Connect

    Boisvert, R.F.; Pozo, R.; Remington, K.; Barrett, R.F.; Dongarra, J.J. /

    1996-05-30

    We describe a repository of data for the testing of numerical algorithms and mathematical software for matrix computations. The repository is designed to accommodate both dense and sparse matrices, as well as software to generate matrices. It has been seeded with the well known Harwell-Boeing sparse matrix collection. The raw data files have been augmented with an integrated World Wide Web interface which describes the matrices in the collection quantitatively and visually, For example, each matrix has a Web page which details its attributes, graphically depicts its sparsity pattern, and provides access to the matrix itself in several formats. In addition, a search mechanism is included which allows retrieval of matrices based on a variety of attributes, such as type and size, as well as through free-text search in abstracts. The URL is http://math.nist.gov/MatrixMarket.

  17. The Matrix Editor for symbolic Jacobians in ALPAL

    SciTech Connect

    Painter, J.F.

    1991-12-01

    ALPAL is a Macsyma-based tool that automatically generates code to solve nonlinear integro-differential equations, given a very high-level specification of the equations to be solved and the numerical methods to be used. The Matrix Editor is a graphical, interactive tool for specifying the handling of Jacobian matrices and linear solvers. It automates such routine but difficult tasks as correctly converting from the data structures used for computing the Jacobian to data structures used by a linear solver. The user specifies what to do only at a high, natural level of abstraction.

  18. Pillared smectite clay coatings for ceramic-matrix composites

    SciTech Connect

    Jagota, S.; Harmer, M.A.; Lemon, M.F.; Jagota, A.; McCarron, E.M. III.

    1995-08-01

    This paper describes a novel route for the low-temperature formation of mullite, from pillared smectite clay precursors, for use as fiber coatings in ceramic-matrix composites. In particular, alumina-pillared bentonite converts in part to mullite at the unusually low temperature of about 800 C. The clay precursors display excellent film-forming capability and have been coated onto silicon carbide fibers. Mechanical tests on composites of the coated fibers and a borosilicate glass demonstrate their success as debond coatings, suggesting that this approach is a viable and simple route to oxide coatings for fibers.

  19. Glass matrix armor

    DOEpatents

    Calkins, Noel C.

    1991-01-01

    An armor system which utilizes glass. A plurality of constraint cells are mounted on a surface of a substrate, which is metal armor plate or a similar tough material, such that the cells almost completely cover the surface of the substrate. Each constraint cell has a projectile-receiving wall parallel to the substrate surface and has sides which are perpendicular to and surround the perimeter of the receiving wall. The cells are mounted such that, in one embodiment, the substrate surface serves as a sixth side or closure for each cell. Each cell has inside of it a plate, termed the front plate, which is parallel to and in contact with substantially all of the inside surface of the receiving wall. The balance of each cell is completely filled with a projectile-abrading material consisting of glass and a ceramic material and, in certain embodiments, a polymeric material. The glass may be in monolithic form or particles of ceramic may be dispersed in a glass matrix. The ceramic material may be in monolithic form or may be in the form of particles dispersed in glass or dispersed in said polymer.

  20. Hypercube matrix computation task

    NASA Technical Reports Server (NTRS)

    Calalo, R.; Imbriale, W.; Liewer, P.; Lyons, J.; Manshadi, F.; Patterson, J.

    1987-01-01

    The Hypercube Matrix Computation (Year 1986-1987) task investigated the applicability of a parallel computing architecture to the solution of large scale electromagnetic scattering problems. Two existing electromagnetic scattering codes were selected for conversion to the Mark III Hypercube concurrent computing environment. They were selected so that the underlying numerical algorithms utilized would be different thereby providing a more thorough evaluation of the appropriateness of the parallel environment for these types of problems. The first code was a frequency domain method of moments solution, NEC-2, developed at Lawrence Livermore National Laboratory. The second code was a time domain finite difference solution of Maxwell's equations to solve for the scattered fields. Once the codes were implemented on the hypercube and verified to obtain correct solutions by comparing the results with those from sequential runs, several measures were used to evaluate the performance of the two codes. First, a comparison was provided of the problem size possible on the hypercube with 128 megabytes of memory for a 32-node configuration with that available in a typical sequential user environment of 4 to 8 megabytes. Then, the performance of the codes was anlyzed for the computational speedup attained by the parallel architecture.

  1. Emergency Response Synchronization Matrix

    1999-06-01

    An emergency response to a disaster is complex, requiring the rapid integration, coordination, and synchronization of multiple levels of governmental and non-governmental organizations from numerous jurisdictions into a unified community response. For example, a community’s response actions to a fixed site hazardous materials incident could occur in an area extending from an on-site storage location to points 25 or more miles away. Response actions are directed and controlled by local governments and agencies situated withinmore » the response area, as well as by state and federal operaticns centers quite removed from the area of impact. Time is critical and the protective action decision-making process is greatly compressed. The response community must carefully plan and coordinate response operations in order to have confidence that they will be effectively implemented when faced with the potentially catastrophic nature of such releases. A graphical depiction of the entire response process via an emergency response synchronization matrix is an effective tool in optimizing the planning, exercising, and implementation of emergency plans. This system—based approach to emergency planning depicts how a community organizes its response tasks across space and time in relation to hazard actions. It provides the opportunity to make real—time adjustments as necessary for maximizing the often limited resources in protecting area residents. A response must involve the entire community and must not be limited by individual jurisdictions and organizations acting on their own without coordination, integration, and synchronization.« less

  2. Hybridized polymer matrix composites

    NASA Technical Reports Server (NTRS)

    House, E. E.; Hoggatt, J. T.; Symonds, W. A.

    1980-01-01

    The extent to which graphite fibers are released from resin matrix composites that are exposed to fire and impact conditions was determined. Laboratory simulations of those conditions that could exist in the event of an aircraft crash and burn situation were evaluated. The effectiveness of various hybridizing concepts in preventing this release of graphite fibers were also evaluated. The baseline (i.e., unhybridized) laminates examined were prepared from commercially available graphite/epoxy, graphite/polyimide, and graphite/phenolic materials. Hybridizing concepts investigated included resin fillers, laminate coatings, resin blending, and mechanical interlocking of the graphite reinforcement. The baseline and hybridized laminates' mechanical properties, before and after isothermal and humidity aging, were also compared. It was found that a small amount of graphite fiber was released from the graphite/epoxy laminates during the burn and impact conditions used in this program. However, the extent to which the fibers were released is not considered a severe enough problem to preclude the use of graphite reinforced composites in civil aircraft structure. It also was found that several hybrid concepts eliminated this fiber release. Isothermal and humidity aging did not appear to alter the fiber release tendencies.

  3. Mining disease state converters for medical intervention of diseases.

    PubMed

    Dong, Guozhu; Duan, Lei; Tang, Changjie

    2010-02-01

    In applications such as gene therapy and drug design, a key goal is to convert the disease state of diseased objects from an undesirable state into a desirable one. Such conversions may be achieved by changing the values of some attributes of the objects. For example, in gene therapy one may convert cancerous cells to normal ones by changing some genes' expression level from low to high or from high to low. In this paper, we define the disease state conversion problem as the discovery of disease state converters; a disease state converter is a small set of attribute value changes that may change an object's disease state from undesirable into desirable. We consider two variants of this problem: personalized disease state converter mining mines disease state converters for a given individual patient with a given disease, and universal disease state converter mining mines disease state converters for all samples with a given disease. We propose a DSCMiner algorithm to discover small and highly effective disease state converters. Since real-life medical experiments on living diseased instances are expensive and time consuming, we use classifiers trained from the datasets of given diseases to evaluate the quality of discovered converter sets. The effectiveness of a disease state converter is measured by the percentage of objects that are successfully converted from undesirable state into desirable state as deemed by state-of-the-art classifiers. We use experiments to evaluate the effectiveness of our algorithm and to show its effectiveness. We also discuss possible research directions for extensions and improvements. We note that the disease state conversion problem also has applications in customer retention, criminal rehabilitation, and company turn-around, where the goal is to convert class membership of objects whose class is an undesirable class.

  4. Ceramic matrix composite article and process of fabricating a ceramic matrix composite article

    DOEpatents

    Cairo, Ronald Robert; DiMascio, Paul Stephen; Parolini, Jason Robert

    2016-01-12

    A ceramic matrix composite article and a process of fabricating a ceramic matrix composite are disclosed. The ceramic matrix composite article includes a matrix distribution pattern formed by a manifold and ceramic matrix composite plies laid up on the matrix distribution pattern, includes the manifold, or a combination thereof. The manifold includes one or more matrix distribution channels operably connected to a delivery interface, the delivery interface configured for providing matrix material to one or more of the ceramic matrix composite plies. The process includes providing the manifold, forming the matrix distribution pattern by transporting the matrix material through the manifold, and contacting the ceramic matrix composite plies with the matrix material.

  5. Entanglement convertibility by sweeping through the quantum phases of the alternating bonds XXZ chain.

    PubMed

    Tzeng, Yu-Chin; Dai, Li; Chung, Ming-Chiang; Amico, Luigi; Kwek, Leong-Chuan

    2016-05-24

    We study the entanglement structure and the topological edge states of the ground state of the spin-1/2 XXZ model with bond alternation. We employ parity-density matrix renormalization group with periodic boundary conditions. The finite-size scaling of Rényi entropies S2 and S∞ are used to construct the phase diagram of the system. The phase diagram displays three possible phases: Haldane type (an example of symmetry protected topological ordered phases), Classical Dimer and Néel phases, the latter bounded by two continuous quantum phase transitions. The entanglement and non-locality in the ground state are studied and quantified by the entanglement convertibility. We found that, at small spatial scales, the ground state is not convertible within the topological Haldane dimer phase. The phenomenology we observe can be described in terms of correlations between edge states. We found that the entanglement spectrum also exhibits a distinctive response in the topological phase: the effective rank of the reduced density matrix displays a specifically large "susceptibility" in the topological phase. These findings support the idea that although the topological order in the ground state cannot be detected by local inspection, the ground state response at local scale can tell the topological phases apart from the non-topological phases.

  6. Entanglement convertibility by sweeping through the quantum phases of the alternating bonds XXZ chain.

    PubMed

    Tzeng, Yu-Chin; Dai, Li; Chung, Ming-Chiang; Amico, Luigi; Kwek, Leong-Chuan

    2016-01-01

    We study the entanglement structure and the topological edge states of the ground state of the spin-1/2 XXZ model with bond alternation. We employ parity-density matrix renormalization group with periodic boundary conditions. The finite-size scaling of Rényi entropies S2 and S∞ are used to construct the phase diagram of the system. The phase diagram displays three possible phases: Haldane type (an example of symmetry protected topological ordered phases), Classical Dimer and Néel phases, the latter bounded by two continuous quantum phase transitions. The entanglement and non-locality in the ground state are studied and quantified by the entanglement convertibility. We found that, at small spatial scales, the ground state is not convertible within the topological Haldane dimer phase. The phenomenology we observe can be described in terms of correlations between edge states. We found that the entanglement spectrum also exhibits a distinctive response in the topological phase: the effective rank of the reduced density matrix displays a specifically large "susceptibility" in the topological phase. These findings support the idea that although the topological order in the ground state cannot be detected by local inspection, the ground state response at local scale can tell the topological phases apart from the non-topological phases. PMID:27216970

  7. Entanglement convertibility by sweeping through the quantum phases of the alternating bonds XXZ chain

    PubMed Central

    Tzeng, Yu-Chin; Dai, Li; Chung, Ming-Chiang; Amico, Luigi; Kwek, Leong-Chuan

    2016-01-01

    We study the entanglement structure and the topological edge states of the ground state of the spin-1/2 XXZ model with bond alternation. We employ parity-density matrix renormalization group with periodic boundary conditions. The finite-size scaling of Rényi entropies S2 and S∞ are used to construct the phase diagram of the system. The phase diagram displays three possible phases: Haldane type (an example of symmetry protected topological ordered phases), Classical Dimer and Néel phases, the latter bounded by two continuous quantum phase transitions. The entanglement and non-locality in the ground state are studied and quantified by the entanglement convertibility. We found that, at small spatial scales, the ground state is not convertible within the topological Haldane dimer phase. The phenomenology we observe can be described in terms of correlations between edge states. We found that the entanglement spectrum also exhibits a distinctive response in the topological phase: the effective rank of the reduced density matrix displays a specifically large “susceptibility” in the topological phase. These findings support the idea that although the topological order in the ground state cannot be detected by local inspection, the ground state response at local scale can tell the topological phases apart from the non-topological phases. PMID:27216970

  8. Matrix Methods to Analytic Geometry.

    ERIC Educational Resources Information Center

    Bandy, C.

    1982-01-01

    The use of basis matrix methods to rotate axes is detailed. It is felt that persons who have need to rotate axes often will find that the matrix method saves considerable work. One drawback is that most students first learning to rotate axes will not yet have studied linear algebra. (MP)

  9. Synthetic Division and Matrix Factorization

    ERIC Educational Resources Information Center

    Barabe, Samuel; Dubeau, Franc

    2007-01-01

    Synthetic division is viewed as a change of basis for polynomials written under the Newton form. Then, the transition matrices obtained from a sequence of changes of basis are used to factorize the inverse of a bidiagonal matrix or a block bidiagonal matrix.

  10. How to Study a Matrix

    ERIC Educational Resources Information Center

    Jairam, Dharmananda; Kiewra, Kenneth A.; Kauffman, Douglas F.; Zhao, Ruomeng

    2012-01-01

    This study investigated how best to study a matrix. Fifty-three participants studied a matrix topically (1 column at a time), categorically (1 row at a time), or in a unified way (all at once). Results revealed that categorical and unified study produced higher: (a) performance on relationship and fact tests, (b) study material satisfaction, and…

  11. On quantization of matrix models

    NASA Astrophysics Data System (ADS)

    Starodubtsev, Artem

    2002-12-01

    The issue of non-perturbative background independent quantization of matrix models is addressed. The analysis is carried out by considering a simple matrix model which is a matrix extension of ordinary mechanics reduced to 0 dimension. It is shown that this model has an ordinary mechanical system evolving in time as a classical solution. But in this treatment the action principle admits a natural modification which results in algebraic relations describing quantum theory. The origin of quantization is similar to that in Adler's generalized quantum dynamics. The problem with extension of this formalism to many degrees of freedom is solved by packing all the degrees of freedom into a single matrix. The possibility to apply this scheme to various matrix models is discussed.

  12. Integrated Solar Power Converters: Wafer-Level Sub-Module Integrated DC/DC Converter

    SciTech Connect

    2012-02-09

    Solar ADEPT Project: CU-Boulder is developing advanced power conversion components that can be integrated into individual solar panels to improve energy yields. The solar energy that is absorbed and collected by a solar panel is converted into useable energy for the grid through an electronic component called an inverter. Many large, conventional solar energy systems use one, central inverter to convert energy. CU-Boulder is integrating smaller, microinverters into individual solar panels to improve the efficiency of energy collection. The University’s microinverters rely on electrical components that direct energy at high speeds and ensure that minimal energy is lost during the conversion process—improving the overall efficiency of the power conversion process. CU-Boulder is designing its power conversion devices for use on any type of solar panel.

  13. Symmetry Analysis of Thermoelectric Energy Converters with Inhomogeneous Legs

    NASA Astrophysics Data System (ADS)

    Korzhuev, M. A.

    2010-09-01

    Symmetry analysis has been applied to thermoelectric energy converters [thermoelectric generators (TEG), coolers (TEC), and heaters (TEH)] with inhomogeneous legs. The features of the crystallographic symmetry of thermoelectric materials and the symmetry of legs, thermocouples, and modules are studied. The effect of symmetry on the figure of merit Z of thermoelectric energy converters is considered. A general rule for proper placement of legs in thermoelectric converters is developed. A modified tetratomic classification for thermoelectric energy converters with inhomogeneous legs (TEGa, TEGb, TEC, and TEH) is proposed. An increase in Z for thermoelectric energy converters with inhomogeneous legs is due to the bulk thermoelectric effect. An increase in Z gives the reduction of irreversible processes in the modules (Joule heating and thermal conductivity), accompanying breaking of the symmetry of the legs. It is found that violations of the symmetry requirements can lead to significant energy losses in converters.

  14. Characterization of advanced thermionic energy converters for modular power units

    NASA Astrophysics Data System (ADS)

    Thayer, Kevin L.; Ramalingam, Mysore L.; Lamp, Thomas R.

    1995-01-01

    The results of the initial characterization of two advanced, heat pipe cooled planar thermionic energy converters are presented. The advanced converters utilize chemical vapor deposited (CVD) rhenium on molybdenum for both the emitter and collector electrodes. Waste heat is rejected from the collector electrode by a niobium heat pipe that contains sodium as the working fluid. Output power densities in the range from 0.7 to 10.43 watts/cm2 were recorded using sweep blasing for emitter temperatures in the range from 1573 to 1950 K. Tests were conducted to investigate the design of a power conversion circuit for a series string of converters. Static loading of the converters was performed to verify the operation of the converters in an actual application. The dynamic switching characteristics of one converter were measured to evaluate the possibility of interfacing a pulse-width modulated (PWM) power regulator directly to a thermionic source.

  15. High-power converters for space applications

    NASA Technical Reports Server (NTRS)

    Park, J. N.; Cooper, Randy

    1991-01-01

    Phase 1 was a concept definition effort to extend space-type dc/dc converter technology to the megawatt level with a weight of less than 0.1 kg/kW (220 lb./MW). Two system designs were evaluated in Phase 1. Each design operates from a 5 kV stacked fuel cell source and provides a voltage step-up to 100 kV at 10 A for charging capacitors (100 pps at a duty cycle of 17 min on, 17 min off). Both designs use an MCT-based, full-bridge inverter, gaseous hydrogen cooling, and crowbar fault protection. The GE-CRD system uses an advanced high-voltage transformer/rectifier filter is series with a resonant tank circuit, driven by an inverter operating at 20 to 50 kHz. Output voltage is controlled through frequency and phase shift control. Fast transient response and stability is ensured via optimal control. Super-resonant operation employing MCTs provides the advantages of lossless snubbing, no turn-on switching loss, use of medium-speed diodes, and intrinsic current limiting under load-fault conditions. Estimated weight of the GE-CRD system is 88 kg (1.5 cu ft.). Efficiency of 94.4 percent and total system loss is 55.711 kW operating at 1 MW load power. The Maxwell system is based on a resonance transformer approach using a cascade of five LC resonant sections at 100 kHz. The 5 kV bus is converted to a square wave, stepped-up to a 100 kV sine wave by the LC sections, rectified, and filtered. Output voltage is controlled with a special series regulator circuit. Estimated weight of the Maxwell system is 83.8 kg (4.0 cu ft.). Efficiency is 87.2 percent and total system loss is 146.411 kW operating at 1 MW load power.

  16. High-power converters for space applications

    NASA Astrophysics Data System (ADS)

    Park, J. N.; Cooper, Randy

    1991-06-01

    Phase 1 was a concept definition effort to extend space-type dc/dc converter technology to the megawatt level with a weight of less than 0.1 kg/kW (220 lb./MW). Two system designs were evaluated in Phase 1. Each design operates from a 5 kV stacked fuel cell source and provides a voltage step-up to 100 kV at 10 A for charging capacitors (100 pps at a duty cycle of 17 min on, 17 min off). Both designs use an MCT-based, full-bridge inverter, gaseous hydrogen cooling, and crowbar fault protection. The GE-CRD system uses an advanced high-voltage transformer/rectifier filter is series with a resonant tank circuit, driven by an inverter operating at 20 to 50 kHz. Output voltage is controlled through frequency and phase shift control. Fast transient response and stability is ensured via optimal control. Super-resonant operation employing MCTs provides the advantages of lossless snubbing, no turn-on switching loss, use of medium-speed diodes, and intrinsic current limiting under load-fault conditions. Estimated weight of the GE-CRD system is 88 kg (1.5 cu ft.). Efficiency of 94.4 percent and total system loss is 55.711 kW operating at 1 MW load power. The Maxwell system is based on a resonance transformer approach using a cascade of five LC resonant sections at 100 kHz. The 5 kV bus is converted to a square wave, stepped-up to a 100 kV sine wave by the LC sections, rectified, and filtered. Output voltage is controlled with a special series regulator circuit. Estimated weight of the Maxwell system is 83.8 kg (4.0 cu ft.). Efficiency is 87.2 percent and total system loss is 146.411 kW operating at 1 MW load power.

  17. A new battery charger/discharger converter. [for spacecraft application

    NASA Technical Reports Server (NTRS)

    Middlebrook, R. D.; Cuk, S.; Behen, W.

    1978-01-01

    A new optimum topology dc-to-dc switching converter is extended to provide bidirectional current flow. The resulting two-quadrant converter can be employed to eliminate the discontinuous current mode in normal unidirectional applications, but is especially suited for spacecraft battery conditioning as a charge-discharge regulator in place of the conventional separate converters. Implementation of the control features and the battery charge current and voltage limits are discussed.

  18. A high voltage power converter for space astronomy applications

    NASA Technical Reports Server (NTRS)

    Ray, David C.; Lampton, Michael L.

    1988-01-01

    A dc-dc low-power, high-voltage converter for use in space is described which furnishes a commandable, low-noise dc output in the range of 0 to -7500 V. The converter is suitable for biasing of detectors commonly employed in space astronomy, microchannel plates, photomultipliers, and gas discharge detectors. The converter's reliability has been demonstrated by accelerated life testing under thermal vacuum. The electrical and mechanical design, packaging, layout and fabrication techniques, and tests employed are described.

  19. Noninterlaced-To-Interlaced Television-Scan Converter

    NASA Technical Reports Server (NTRS)

    Morales, Sergio

    1988-01-01

    Computer text and ordinary images displayed together without text jitter. Scan converter enables superposition of alphanumerical text generated by computer-driven video generator on National Television System Committee (NTSC) standard interlaced-scan image. Made of commercially available integrated circuits and operates in conjunction with NTSC synchronizing-signal generator. Standard television picture transmitted in two interlaced fields. Without scan converter, text image moves up and down by one line as fields change. With scan converter, text image stands still.

  20. Power Converters Maximize Outputs Of Solar Cell Strings

    NASA Technical Reports Server (NTRS)

    Frederick, Martin E.; Jermakian, Joel B.

    1993-01-01

    Microprocessor-controlled dc-to-dc power converters devised to maximize power transferred from solar photovoltaic strings to storage batteries and other electrical loads. Converters help in utilizing large solar photovoltaic arrays most effectively with respect to cost, size, and weight. Main points of invention are: single controller used to control and optimize any number of "dumb" tracker units and strings independently; power maximized out of converters; and controller in system is microprocessor.

  1. Another look at Statics and Dynamics of Switching Power Converters

    NASA Astrophysics Data System (ADS)

    Sasaki, Seigo; Watanabe, Haruo

    Three types of switching power supply, which are buck, boost, buck/boost converter, are statically and dynamically analysed. A framework of large signal analysis presents characteristics of converters which vary with operating points, and discusses a relationship between statics and dynamics. It is shown that boost and buck/boost converters substantially change their characteristics. There exists the operating points where for low frequencies the phases become -90° or -180° and the gains fall off to low values. The phenomenon is characterized by a zero of transfer function of the converter and also by the statics.

  2. Hybrid Voltage-Multipliers Based Switching Power Converters

    NASA Astrophysics Data System (ADS)

    Rosas-Caro, Julio C.; Mayo-Maldonado, Jonathan C.; Vazquez-Bautista, Rene Fabian; Valderrabano-Gonzalez, Antonio; Salas-Cabrera, Ruben; Valdez-Resendiz, Jesus Elias

    2011-08-01

    This work presents a derivation of PWM DC-DC hybrid converters by combining traditional converters with the Cockcroft-Walton voltage multiplier, the voltage multiplier of each converter is driven with the same transistor of the basic topology; this fact makes the structure of the new converters very simple and provides high-voltage gain. The traditional topologies discussed are the boost, buck-boost, Cuk and SEPIC. They main features of the discussed family are: (i) high-voltage gain without using extreme duty cycles or transformers, which allow high switching frequency and (ii) low voltage stress in switching devices, along with modular structures, and more output levels can be added without modifying the main circuit, which is highly desirable in some applications such as renewable energy generation systems. It is shown how a multiplier converter can become a generalized topology and how some of the traditional converters and several state-of-the-art converters can be derived from the generalized topologies and vice-versa. All the discussed converters were simulated, additionally experimental results are provided with an interleaved multiplier converter.

  3. Cholecystokinin-converting enzymes in brain.

    PubMed Central

    Malesci, A; Straus, E; Yalow, R S

    1980-01-01

    Crude extracts of porcine cerebral cortical tissue convert cholecystokinin (CCK) to its COOH-terminal fragments, the dodecapeptide (CCK-12) and the octapeptide (CCK-8). The Sephadex G-75 void volume eluate of the crude extract cleaves the arginine-isoleucine bond and effects conversion only to CCK-12; the Sephadex G-50 void volume eluate of the same extract cleaves the arginine-aspartate bond as well, so that both CCK-12 and CCK-8 are end products. Thus, there are at least two enzymes; the one involved in the conversion to CCK-12 is of larger molecular radius than the other. The Km for the cleavage of CCK at the arginine-isoleucine bond by the Sephadex G-75 void volume eluate enzyme is 1.1 X 10(-6) M; the Km for trypsin cleavage of the same bond is 4.7 x 10(-6) M. The lower Vmax for the brain enzyme (1.5 x 10(-11) mol/min per g of extract) compared with trypsin (66 x 10(-11) mol/min per g of trypsin) simply reflects the lesser degree of purify of the brain extract than of the highly purified trypsin. Images PMID:6987659

  4. [Angiotensin converting enzyme and Alzheimer's disease].

    PubMed

    Kugaevskaia, E V

    2013-01-01

    Alzheimer's disease (AD) is an incurable degenerative disease of the central nervous system, leading to dementia. The basis of AD is neurodegenerative process that leads to death of neurons in the cerebral cortex. This neurodegenerative process is associated with the formation of neurofibrillary tangles in the brain and the deposition of senile plaques, the main component of which is a beta-amyloid peptide (Abeta). Risk factors for AD are age, as well as hypertension, atherosclerosis, diabetes and hypercholesterolemia in the pathogenesis of which involved angiotensin converting enzyme (ACE)--key enzyme of the renin-angiotensin (RAS) and kallikrein-kinin (KKS) systems. Recently it was discovered that ACE, along with other metallopeptidases, participates in the metabolism of Abeta, cleaving the bonds at the N-terminal and C-terminal region of the molecule Abeta. The role of the ACE in the degradation processes of Abeta takes an interest. It is associated with the fact that the using of ACE inhibitors is the main therapeutic approach used in the treatment of various forms of hypertension and other cardiovascular diseases. However, until now not been resolved, can be used antihypertensive drugs that inhibit RAS for the treatment or prevention of AD. Currently, there are numerous studies on finding the relationship between RAS and AD. PMID:23650720

  5. Converting sensitive waste into cleaner energy

    SciTech Connect

    Schriner, D.; Skinner, R.

    1997-10-01

    The destruction of sensitive unclassified information (SUI) has always been expensive due to the need for special controls to ensure its protection from disclosure to unauthorized persons. The sensitive documents were shredded, buried at the landfill, or sent to a recycling company. The Department of Energy (DOE) Idaho National Engineering and Environmental Laboratory (INEEL), operated by Lockheed Martin Idaho Technologies Company (LMITCO), has created an innovative method to dispose of its sensitive unclassified paper waste which has security, economic, and environmental benefits. A new cubing facility at the INEEL converts office and industrial waste into compact cubes which are then combined with coal and burned as a source of heat and process steam to run the Idaho Chemical Processing Plant (ICPP) facility. The process-engineered fuel, consisting of 25% cubes and 75% coal, bums cleaner than coal with lower emissions of sulfur dioxide and nitrogen oxides. The alternative fuel also reduces fuel costs, eliminates paying a recycling company, reduces the expense of landfill disposal, increases the life of the landfill, and provides energy to operate a large facility. The Operations Security (OPSEC) team capitalized on this waste to energy technology by recommending that the large quantities of sensitive information (documents) generated at the INEEL be disposed of in this manner. In addition to the economic and environmental benefits, this disposal method minimizes the vulnerabilities of SUI from disclosure to unauthorized personnel. The {open_quotes}cuber{close_quotes} technology has potential application in government and industry for protection of SUI.

  6. Image processing to optimize wave energy converters

    NASA Astrophysics Data System (ADS)

    Bailey, Kyle Marc-Anthony

    The world is turning to renewable energies as a means of ensuring the planet's future and well-being. There have been a few attempts in the past to utilize wave power as a means of generating electricity through the use of Wave Energy Converters (WEC), but only recently are they becoming a focal point in the renewable energy field. Over the past few years there has been a global drive to advance the efficiency of WEC. Placing a mechanical device either onshore or offshore that captures the energy within ocean surface waves to drive a mechanical device is how wave power is produced. This paper seeks to provide a novel and innovative way to estimate ocean wave frequency through the use of image processing. This will be achieved by applying a complex modulated lapped orthogonal transform filter bank to satellite images of ocean waves. The complex modulated lapped orthogonal transform filterbank provides an equal subband decomposition of the Nyquist bounded discrete time Fourier Transform spectrum. The maximum energy of the 2D complex modulated lapped transform subband is used to determine the horizontal and vertical frequency, which subsequently can be used to determine the wave frequency in the direction of the WEC by a simple trigonometric scaling. The robustness of the proposed method is provided by the applications to simulated and real satellite images where the frequency is known.

  7. Durability of ceramic catalytic converters for motorcycles

    SciTech Connect

    Reddy, K.P.; Scott, P.L.; Hwang, H.S.; Mooney, J.J.

    1995-12-31

    Motorcycle exhaust emission standards throughout the world are becoming more stringent. Emission control systems utilizing the catalytic converter are already in production in Taiwan for 2-stroke engine motorcycles. Catalysts designed for 2-stroke engines encounter a more severe exhaust environment than do those designed for 4-stroke engines. The two aspects of increased severity are the higher temperatures and higher stresses due to engine vibrations. Precious metal catalysts have been designed to operate in the thermal environment of 2-stroke engines and such catalysts have been successfully applied to both metal and ceramic substrates. However, until now, only the metal substrate catalysts have been utilized in motorcycle application. Ceramic based catalysts have not been considered because the mounting material that holds the catalyst substrate in place did not have enough durability to withstand the thermal/vibrational forces encountered in 2-stroke engine exhaust. Ceramic substrates have many advantages such as superior high temperature strength, which is especially important for the 2-stroke engine application, flexibility in cell shape and density, and lower cost. To realize these benefits, efforts were made in this study to develop better mounting systems. The results of this effort indicate that the durability requirements of 2-stroke engine can be met with the ceramic catalyst substrates if the improved mounting designs reported in the present study are employed.

  8. Graphene optical-to-thermal converter

    NASA Astrophysics Data System (ADS)

    Manjavacas, Alejandro; Thongrattanasiri, Sukosin; Greffet, Jean-Jacques; Garcia de Abajo, Javier

    2015-03-01

    Infrared plasmons in doped graphene nanostructures produce large optical absorption that can be used for narrow-band thermal light emission at tunable frequencies that strongly depend on the doping charge. By virtue of Kirchhoff's law, thermal light emission is proportional to the absorption, thus resulting in narrow emission lines associated with the electrically controlled plasmons of heated graphene. Here we show that realistic designs of graphene plasmonic structures can release over 90% of the emission through individual infrared lines with 1% bandwidth. We examine anisotropic graphene structures in which efficient heating can be produced upon optical pumping tuned to a plasmonic absorption resonance situated in the blue region relative to the thermal emission. An incoherent thermal light converter is thus achieved. Our results open a new approach for designing tunable nanoscale infrared light sources. A.M. acknowledges financial support from the Welch foundation through the J. Evans Attwell-Welch Postdoctoral Fellowship Program of the Smalley Institute of Rice University (Grant L-C-004).

  9. Bremsstrahlung converter debris shields: test and analysis

    SciTech Connect

    Reedy, E.D. Jr.; Perry, F.C.

    1983-10-01

    Electron beam accelerators are commonly used to create bremsstrahlung x-rays for effects testing. Typically, the incident electron beam strikes a sandwich of three materials: (1) a conversion foil, (2) an electron scavenger, and (3) a debris shield. Several laboratories, including Sandia National Laboratories, are developing bremsstrahlung x-ray sources with much larger test areas (approx. 200 to 500 cm/sup 2/) than ever used before. Accordingly, the debris shield will be much larger than before and subject to loads which could cause shield failure. To prepare for this eventuality, a series of tests were run on the Naval Surface Weapons Center's Casino electron beam accelerator (approx. 1 MeV electrons, 100 ns FWHM pulse, 45 kJ beam energy). The primary goal of these tests was to measure the stress pulse which loads a debris shield. These measurements were made with carbon gages mounted on the back of the converter sandwich. At an electron beam fluence of about 1 kJ/cm/sup 2/, the measured peak compressive stress was typically in the 1 to 2 kbar range. Measured peak compressive stress scaled in a roughly linear manner with fluence level as the fluence level was increased to 10 kJ/cm/sup 2/. The duration of the compressive pulse was on the order of microseconds. In addition to the stress wave measurements, a limited number of tests were made to investigate the type of damage generated in several potential shield materials.

  10. Converting ICD-9 to ICD-10.

    PubMed

    Stephens, James H; Ledlow, Gerald R; Fockler, Thomas V

    2016-01-01

    Implementing the International Classification of Diseases, Ninth Revision (ICD-9) to International Classification of Diseases, Tenth Revision (ICD-10) conversion on October 1, 2015, in the United States has been a long-term goal. While most countries in the world converted more than 10 years ago, the United States was still using ICD-9. Many countries in the world have a single-payer healthcare system, while there are thousands of different healthcare organizations (providers and payers) that presently exist in the United States. With so many different software platforms for healthcare providers and payers, the conversion had become that much more complicated and capital intensive for all healthcare organizations in the country. A few of the present delay reasons to the ICD-10 conversion in past years were the concurrent timelines for meeting meaningful use requirements for the electronic health record, testing with external payers and upgrades from vendors which added complexities and extra costs. The authors examine the reasoning behind the conversion as well as the delays, before making the conversion on October 1, 2015, and review the question regarding whether the government's decision to push the date back a year would have been helpful. PMID:26980201

  11. M-theoretic matrix models

    NASA Astrophysics Data System (ADS)

    Grassi, Alba; Mariño, Marcos

    2015-02-01

    Some matrix models admit, on top of the usual 't Hooft expansion, an M-theory-like expansion, i.e. an expansion at large N but where the rest of the parameters are fixed, instead of scaling with N . These models, which we call M-theoretic matrix models, appear in the localization of Chern-Simons-matter theories, and also in two-dimensional statistical physics. Generically, their partition function receives non-perturbative corrections which are not captured by the 't Hooft expansion. In this paper, we discuss general aspects of these type of matrix integrals and we analyze in detail two different examples. The first one is the matrix model computing the partition function of supersymmetric Yang-Mills theory in three dimensions with one adjoint hypermultiplet and N f fundamentals, which has a conjectured M-theory dual, and which we call the N f matrix model. The second one, which we call the polymer matrix model, computes form factors of the 2d Ising model and is related to the physics of 2d polymers. In both cases we determine their exact planar limit. In the N f matrix model, the planar free energy reproduces the expected behavior of the M-theory dual. We also study their M-theory expansion by using Fermi gas techniques, and we find non-perturbative corrections to the 't Hooft expansion.

  12. The matrix of inspiration

    NASA Astrophysics Data System (ADS)

    Oehlmann, Dietmar; Ohlmann, Odile M.; Danzebrink, Hans U.

    2005-04-01

    perform this exchange, as a matrix, understood as source, of new ideas.

  13. Development of a wind converter and investigation of its operational function. Part 1: Technical description of the wind energy converter

    NASA Astrophysics Data System (ADS)

    Molly, J. P.; Steinheber, R.

    1982-11-01

    A 10 kW wind energy converter was developed by using as far possible standard serial production parts. The design criteria and the description of the essential machinery components of the MODA 10 wind energy converter are discussed. For some special load cases the safety calculation of the important components is shown. The blade control system which qualified for small wind energy converters, is explained. Weight and cost of the MODA 10 are considered.

  14. Canonical density matrix perturbation theory.

    PubMed

    Niklasson, Anders M N; Cawkwell, M J; Rubensson, Emanuel H; Rudberg, Elias

    2015-12-01

    Density matrix perturbation theory [Niklasson and Challacombe, Phys. Rev. Lett. 92, 193001 (2004)] is generalized to canonical (NVT) free-energy ensembles in tight-binding, Hartree-Fock, or Kohn-Sham density-functional theory. The canonical density matrix perturbation theory can be used to calculate temperature-dependent response properties from the coupled perturbed self-consistent field equations as in density-functional perturbation theory. The method is well suited to take advantage of sparse matrix algebra to achieve linear scaling complexity in the computational cost as a function of system size for sufficiently large nonmetallic materials and metals at high temperatures. PMID:26764847

  15. High Temperature Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    1985-01-01

    These are the proceedings of the High Temperature Polymer Matrix Composites Conference held at the NASA Lewis Research Center on March 16 to 18, 1983. The purpose of the conference is to provide scientists and engineers working in the field of high temperature polymer matrix composites an opportunity to review, exchange, and assess the latest developments in this rapidly expanding area of materials technology. Technical papers are presented in the following areas: (1) matrix development; (2) adhesive development; (3) characterization; (4) environmental effects; and (5) applications.

  16. Genotype imputation via matrix completion.

    PubMed

    Chi, Eric C; Zhou, Hua; Chen, Gary K; Del Vecchyo, Diego Ortega; Lange, Kenneth

    2013-03-01

    Most current genotype imputation methods are model-based and computationally intensive, taking days to impute one chromosome pair on 1000 people. We describe an efficient genotype imputation method based on matrix completion. Our matrix completion method is implemented in MATLAB and tested on real data from HapMap 3, simulated pedigree data, and simulated low-coverage sequencing data derived from the 1000 Genomes Project. Compared with leading imputation programs, the matrix completion algorithm embodied in our program MENDEL-IMPUTE achieves comparable imputation accuracy while reducing run times significantly. Implementation in a lower-level language such as Fortran or C is apt to further improve computational efficiency. PMID:23233546

  17. Matrix Elements for Hylleraas CI

    NASA Astrophysics Data System (ADS)

    Harris, Frank E.

    The limitation to at most a single interelectron distance in individual configurations of a Hylleraas-type multiconfiguration wave function restricts significantly the types of integrals occurring in matrix elements for energy calculations, but even then if the formulation is not handled efficiently the angular parts of these integrals escalate to create expressions of great complexity. This presentation reviews ways in which the angular-momentum calculus can be employed to systematize and simplify the matrix element formulas, particularly those for the kinetic-energy matrix elements.

  18. Canonical density matrix perturbation theory.

    PubMed

    Niklasson, Anders M N; Cawkwell, M J; Rubensson, Emanuel H; Rudberg, Elias

    2015-12-01

    Density matrix perturbation theory [Niklasson and Challacombe, Phys. Rev. Lett. 92, 193001 (2004)] is generalized to canonical (NVT) free-energy ensembles in tight-binding, Hartree-Fock, or Kohn-Sham density-functional theory. The canonical density matrix perturbation theory can be used to calculate temperature-dependent response properties from the coupled perturbed self-consistent field equations as in density-functional perturbation theory. The method is well suited to take advantage of sparse matrix algebra to achieve linear scaling complexity in the computational cost as a function of system size for sufficiently large nonmetallic materials and metals at high temperatures.

  19. Converting hard copy documents for electronic dissemination

    SciTech Connect

    Hoffman, F.

    1994-12-31

    Since the advent of computer systems, the goal of a paperless office, and even a paperless society, has been pursued. While the normal paper flow in an organization is far from totally automated, particularly for items requiring signatures or authorizations, electronic information dissemination is becoming an almost simple task. The reasons for providing on-line documents are many and include faster and easier access for everyone, elimination of printing costs, reduction of wasted shelf and desk space, and the security of having a centrally-located, always up-to-date document. New computer software even provides the user with the ability to annotate documents and to have bookmarks so that the old scribbled-in and dog-eared manual can be replaced without loosing this `customizability`. Moreover, new hypermedia capabilities mean that documents can be read in a non-linear fashion and can include color figures and photographs, audio, and even animation sequences, capabilities which exceed those of paper. The proliferation of network-based information servers, coupled with the growth of the Internet, has enticed academic, governmental, and even commercial organizations to provide increasing numbers of documents and data bases in electronic form via the network, not just to internal staff, but to the public as well. Much of this information, which includes everything from mundane company procedures to spiffy marketing brochures, was previously published only in hard copy. Converting existing documents to electronic form and producing only electronic versions of new documents poses some interesting challenges to the maintainer or author.

  20. Matrix product operators, matrix product states, and ab initio density matrix renormalization group algorithms

    NASA Astrophysics Data System (ADS)

    Chan, Garnet Kin-Lic; Keselman, Anna; Nakatani, Naoki; Li, Zhendong; White, Steven R.

    2016-07-01

    Current descriptions of the ab initio density matrix renormalization group (DMRG) algorithm use two superficially different languages: an older language of the renormalization group and renormalized operators, and a more recent language of matrix product states and matrix product operators. The same algorithm can appear dramatically different when written in the two different vocabularies. In this work, we carefully describe the translation between the two languages in several contexts. First, we describe how to efficiently implement the ab initio DMRG sweep using a matrix product operator based code, and the equivalence to the original renormalized operator implementation. Next we describe how to implement the general matrix product operator/matrix product state algebra within a pure renormalized operator-based DMRG code. Finally, we discuss two improvements of the ab initio DMRG sweep algorithm motivated by matrix product operator language: Hamiltonian compression, and a sum over operators representation that allows for perfect computational parallelism. The connections and correspondences described here serve to link the future developments with the past and are important in the efficient implementation of continuing advances in ab initio DMRG and related algorithms.

  1. Matrix product operators, matrix product states, and ab initio density matrix renormalization group algorithms.

    PubMed

    Chan, Garnet Kin-Lic; Keselman, Anna; Nakatani, Naoki; Li, Zhendong; White, Steven R

    2016-07-01

    Current descriptions of the ab initio density matrix renormalization group (DMRG) algorithm use two superficially different languages: an older language of the renormalization group and renormalized operators, and a more recent language of matrix product states and matrix product operators. The same algorithm can appear dramatically different when written in the two different vocabularies. In this work, we carefully describe the translation between the two languages in several contexts. First, we describe how to efficiently implement the ab initio DMRG sweep using a matrix product operator based code, and the equivalence to the original renormalized operator implementation. Next we describe how to implement the general matrix product operator/matrix product state algebra within a pure renormalized operator-based DMRG code. Finally, we discuss two improvements of the ab initio DMRG sweep algorithm motivated by matrix product operator language: Hamiltonian compression, and a sum over operators representation that allows for perfect computational parallelism. The connections and correspondences described here serve to link the future developments with the past and are important in the efficient implementation of continuing advances in ab initio DMRG and related algorithms.

  2. Matrix product operators, matrix product states, and ab initio density matrix renormalization group algorithms.

    PubMed

    Chan, Garnet Kin-Lic; Keselman, Anna; Nakatani, Naoki; Li, Zhendong; White, Steven R

    2016-07-01

    Current descriptions of the ab initio density matrix renormalization group (DMRG) algorithm use two superficially different languages: an older language of the renormalization group and renormalized operators, and a more recent language of matrix product states and matrix product operators. The same algorithm can appear dramatically different when written in the two different vocabularies. In this work, we carefully describe the translation between the two languages in several contexts. First, we describe how to efficiently implement the ab initio DMRG sweep using a matrix product operator based code, and the equivalence to the original renormalized operator implementation. Next we describe how to implement the general matrix product operator/matrix product state algebra within a pure renormalized operator-based DMRG code. Finally, we discuss two improvements of the ab initio DMRG sweep algorithm motivated by matrix product operator language: Hamiltonian compression, and a sum over operators representation that allows for perfect computational parallelism. The connections and correspondences described here serve to link the future developments with the past and are important in the efficient implementation of continuing advances in ab initio DMRG and related algorithms. PMID:27394094

  3. Aggrecanases and cartilage matrix degradation

    PubMed Central

    Nagase, Hideaki; Kashiwagi, Masahide

    2003-01-01

    The loss of extracellular matrix macromolecules from the cartilage results in serious impairment of joint function. Metalloproteinases called 'aggrecanases' that cleave the Glu373–Ala374 bond of the aggrecan core protein play a key role in the early stages of cartilage destruction in rheumatoid arthritis and in osteoarthritis. Three members of the ADAMTS family of proteinases, ADAMTS-1, ADAMTS-4 and ADAMTS-5, have been identified as aggrecanases. Matrix metalloproteinases, which are also found in arthritic joints, cleave aggrecans, but at a distinct site from the aggrecanases (i.e. Asn341–Phe342). The present review discuss the enzymatic properties of the three known aggrecanases, the regulation of their activities, and their role in cartilage matrix breakdown during the development of arthritis in relation to the action of matrix metalloproteinases. PMID:12718749

  4. Stochastic determination of matrix determinants.

    PubMed

    Dorn, Sebastian; Ensslin, Torsten A

    2015-07-01

    Matrix determinants play an important role in data analysis, in particular when Gaussian processes are involved. Due to currently exploding data volumes, linear operations-matrices-acting on the data are often not accessible directly but are only represented indirectly in form of a computer routine. Such a routine implements the transformation a data vector undergoes under matrix multiplication. While efficient probing routines to estimate a matrix's diagonal or trace, based solely on such computationally affordable matrix-vector multiplications, are well known and frequently used in signal inference, there is no stochastic estimate for its determinant. We introduce a probing method for the logarithm of a determinant of a linear operator. Our method rests upon a reformulation of the log-determinant by an integral representation and the transformation of the involved terms into stochastic expressions. This stochastic determinant determination enables large-size applications in Bayesian inference, in particular evidence calculations, model comparison, and posterior determination.

  5. Extracellular matrix and wound healing.

    PubMed

    Maquart, F X; Monboisse, J C

    2014-04-01

    Extracellular matrix has been known for a long time as an architectural support for the tissues. Many recent data, however, have shown that extracellular matrix macromolecules (collagens, elastin, glycosaminoglycans, proteoglycans and connective tissue glycoproteins) are able to regulate many important cell functions, such as proliferation, migration, protein synthesis or degradation, apoptosis, etc., making them able to play an important role in the wound repair process. Not only the intact macromolecules but some of their specific domains, that we called "Matrikines", are also able to regulate many cell activities. In this article, we will summarize main findings showing the effects of extracellular matrix macromolecules and matrikines on connective tissue and epithelial cells, particularly in skin, and their potential implication in the wound healing process. These examples show that extracellular matrix macromolecules or some of their specific domains may play a major role in wound healing. Better knowledge of these interactions may suggest new therapeutic targets in wound healing defects. PMID:24650524

  6. Performance Appraisal for Matrix Management.

    ERIC Educational Resources Information Center

    Edwards, M. R.; Sproull, J. Ruth

    1985-01-01

    A matrix management system designed for use by a highly technical nuclear weapons research and development facility to improve productivity and flexibility by the use of multiple authority, responsibility, and accountability relationships is described. (MSE)

  7. Fast-response frequency-to-analog converter

    NASA Technical Reports Server (NTRS)

    Hagihara, F. S.

    1967-01-01

    Frequency-to-analog converter has a fast response time and a low ripple. The circuit uses a frequency-to-pulse converter which provides two pulse trains, both at the same frequency as that of the input signal, but with a 10 microsecond difference between the trains.

  8. BabeLO--An Extensible Converter of Programming Exercises Formats

    ERIC Educational Resources Information Center

    Queiros, R.; Leal, J. P.

    2013-01-01

    In the last two decades, there was a proliferation of programming exercise formats that hinders interoperability in automatic assessment. In the lack of a widely accepted standard, a pragmatic solution is to convert content among the existing formats. BabeLO is a programming exercise converter providing services to a network of heterogeneous…

  9. Digital parallel-to-series pulse-train converter

    NASA Technical Reports Server (NTRS)

    Hussey, J.

    1971-01-01

    Circuit converts number represented as two level signal on n-bit lines to series of pulses on one of two lines, depending on sign of number. Converter accepts parallel binary input data and produces number of output pulses equal to number represented by input data.

  10. 40 CFR 90.319 - NOX converter check.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) CONTROL OF EMISSIONS FROM NONROAD SPARK-IGNITION ENGINES AT OR BELOW 19 KILOWATTS Emission Test Equipment Provisions § 90.319 NOX converter check. (a) The efficiency of the converter used for the conversion of NO2... procedure described in paragraphs (a)(2) through (a)(8) of this section, test the efficiency of...

  11. Low input voltage converter/regulator minimizes external disturbances

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Low-input voltage converter/regulator constructed in a coaxial configuration minimizes external magnetic field disturbance, suppresses radio noise interference, and provides excellent heat transfer from power transistors. It converts the output of fuel and solar cells, thermionic diodes, thermoelectric generators, and electrochemical batteries to a 28 V dc output.

  12. Modeling the full-bridge series-resonant power converter

    NASA Technical Reports Server (NTRS)

    King, R. J.; Stuart, T. A.

    1982-01-01

    A steady state model is derived for the full-bridge series-resonant power converter. Normalized parametric curves for various currents and voltages are then plotted versus the triggering angle of the switching devices. The calculations are compared with experimental measurements made on a 50 kHz converter and a discussion of certain operating problems is presented.

  13. Intelligent dc-dc Converter Technology Developed and Tested

    NASA Technical Reports Server (NTRS)

    Button, Robert M.

    2001-01-01

    The NASA Glenn Research Center and the Cleveland State University have developed a digitally controlled dc-dc converter to research the benefits of flexible, digital control on power electronics and systems. Initial research and testing has shown that conventional dc-dc converters can benefit from improved performance by using digital-signal processors and nonlinear control algorithms.

  14. Sequential color video to parallel color video converter

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The engineering design, development, breadboard fabrication, test, and delivery of a breadboard field sequential color video to parallel color video converter is described. The converter was designed for use onboard a manned space vehicle to eliminate a flickering TV display picture and to reduce the weight and bulk of previous ground conversion systems.

  15. 32 CFR 538.4 - Convertibility of military payment certificates.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 3 2012-07-01 2009-07-01 true Convertibility of military payment certificates... AND ACCOUNTS MILITARY PAYMENT CERTIFICATES § 538.4 Convertibility of military payment certificates. (a) For authorized personnel. Authorized personnel having in their possession military...

  16. 32 CFR 538.4 - Convertibility of military payment certificates.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 3 2011-07-01 2009-07-01 true Convertibility of military payment certificates... AND ACCOUNTS MILITARY PAYMENT CERTIFICATES § 538.4 Convertibility of military payment certificates. (a) For authorized personnel. Authorized personnel having in their possession military...

  17. 32 CFR 538.4 - Convertibility of military payment certificates.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 3 2013-07-01 2013-07-01 false Convertibility of military payment certificates... AND ACCOUNTS MILITARY PAYMENT CERTIFICATES § 538.4 Convertibility of military payment certificates. (a) For authorized personnel. Authorized personnel having in their possession military...

  18. Program Converts VAX Floating-Point Data To UNIX

    NASA Technical Reports Server (NTRS)

    Alves, Marcos; Chapman, Bruce; Chu, Eugene

    1996-01-01

    VAX Floating Point to Host Floating Point Conversion (VAXFC) software converts non-ASCII files to unformatted floating-point representation of UNIX machine. This is done by reading bytes bit by bit, converting them to floating-point numbers, then writing results to another file. Useful when data files created by VAX computer must be used on other machines. Written in C language.

  19. 32 CFR 538.4 - Convertibility of military payment certificates.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 3 2014-07-01 2014-07-01 false Convertibility of military payment certificates. 538.4 Section 538.4 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY CLAIMS AND ACCOUNTS MILITARY PAYMENT CERTIFICATES § 538.4 Convertibility of military payment certificates....

  20. 26 CFR 1.544-5 - Convertible securities.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 26 Internal Revenue 7 2011-04-01 2009-04-01 true Convertible securities. 1.544-5 Section 1.544-5...) INCOME TAXES (CONTINUED) Personal Holding Companies § 1.544-5 Convertible securities. Under section 544(b) outstanding securities of a corporation such as bonds, debentures, or other corporate obligations,...

  1. 32 CFR 538.4 - Convertibility of military payment certificates.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 3 2010-07-01 2010-07-01 true Convertibility of military payment certificates. 538.4 Section 538.4 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY CLAIMS AND ACCOUNTS MILITARY PAYMENT CERTIFICATES § 538.4 Convertibility of military payment certificates....

  2. 40 CFR 91.319 - NOX converter check.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... converter check. (a) The efficiency of the converter used for the conversion of NO2 to NO is tested as given... of the NO concentration). The NOX analyzer must be in the NO mode so that the span gas does not pass..., then use the highest range which will give the reduction. (6) Switch the NO analyzer to the NOX...

  3. 40 CFR 90.319 - NOX converter check.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Provisions § 90.319 NOX converter check. (a) The efficiency of the converter used for the conversion of NO2... percent of the NO concentration). The NOX analyzer must be in the NO mode so that the span gas does not... the highest range which will give the reduction. (6) Switch the NO analyzer to the NOX mode...

  4. 40 CFR 90.319 - NOX converter check.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Provisions § 90.319 NOX converter check. (a) The efficiency of the converter used for the conversion of NO2... percent of the NO concentration). The NOX analyzer must be in the NO mode so that the span gas does not... the highest range which will give the reduction. (6) Switch the NO analyzer to the NOX mode...

  5. 40 CFR 90.319 - NOX converter check.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Provisions § 90.319 NOX converter check. (a) The efficiency of the converter used for the conversion of NO2... percent of the NO concentration). The NOX analyzer must be in the NO mode so that the span gas does not... the highest range which will give the reduction. (6) Switch the NO analyzer to the NOX mode...

  6. 40 CFR 91.319 - NOX converter check.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... converter check. (a) The efficiency of the converter used for the conversion of NO2 to NO is tested as given... of the NO concentration). The NOX analyzer must be in the NO mode so that the span gas does not pass..., then use the highest range which will give the reduction. (6) Switch the NO analyzer to the NOX...

  7. 40 CFR 91.319 - NOX converter check.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... converter check. (a) The efficiency of the converter used for the conversion of NO2 to NO is tested as given... of the NO concentration). The NOX analyzer must be in the NO mode so that the span gas does not pass..., then use the highest range which will give the reduction. (6) Switch the NO analyzer to the NOX...

  8. 26 CFR 1.544-5 - Convertible securities.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 26 Internal Revenue 7 2010-04-01 2010-04-01 true Convertible securities. 1.544-5 Section 1.544-5...) INCOME TAXES (CONTINUED) Personal Holding Companies § 1.544-5 Convertible securities. Under section 544(b) outstanding securities of a corporation such as bonds, debentures, or other corporate obligations,...

  9. Superconducting A/D converter using latching comparators

    SciTech Connect

    Hamilton, C.A.; Kautz, R.L.; Loyld, F.L.

    1985-03-01

    This paper describes the design and performance of a six-bit A/D converter using fast edge latching comparators. Simulations predicting conversion times of 100 ps and 100 MHz signal bandwidth are verified experimentally. The addition of a superconducting track/hold circuit in front of the A/D converter is expected to substantially improve the signal bandwidth.

  10. 26 CFR 1.544-5 - Convertible securities.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 26 Internal Revenue 7 2013-04-01 2013-04-01 false Convertible securities. 1.544-5 Section 1.544-5...) INCOME TAXES (CONTINUED) Personal Holding Companies § 1.544-5 Convertible securities. Under section 544(b) outstanding securities of a corporation such as bonds, debentures, or other corporate obligations,...

  11. 26 CFR 1.544-5 - Convertible securities.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 26 Internal Revenue 7 2012-04-01 2012-04-01 false Convertible securities. 1.544-5 Section 1.544-5...) INCOME TAXES (CONTINUED) Personal Holding Companies § 1.544-5 Convertible securities. Under section 544(b) outstanding securities of a corporation such as bonds, debentures, or other corporate obligations,...

  12. Universal Keplerian state transition matrix

    NASA Technical Reports Server (NTRS)

    Shepperd, S. W.

    1985-01-01

    A completely general method for computing the Keplerian state transition matrix in terms of Goodyear's universal variables is presented. This includes a new scheme for solving Kepler's problem which is a necessary first step to computing the transition matrix. The Kepler problem is solved in terms of a new independent variable requiring the evaluation of only one transcendental function. Furthermore, this transcendental function may be conveniently evaluated by means of a Gaussian continued fraction.

  13. Molybdenum disilicide alloy matrix composite

    DOEpatents

    Petrovic, J.J.; Honnell, R.E.; Gibbs, W.S.

    1991-12-03

    Compositions of matter consisting of matrix materials having silicon carbide dispersed throughout them and methods of making the compositions are disclosed. A matrix material is an alloy of an intermetallic compound, molybdenum disilicide, and at least one secondary component which is a refractory silicide. The silicon carbide dispersant may be in the form of VLS whiskers, VS whiskers, or submicron powder or a mixture of these forms. 3 figures.

  14. Molybdenum disilicide alloy matrix composite

    DOEpatents

    Petrovic, John J.; Honnell, Richard E.; Gibbs, W. Scott

    1991-01-01

    Compositions of matter consisting of matrix materials having silicon carbide dispersed throughout them and methods of making the compositions. A matrix material is an alloy of an intermetallic compound, molybdenum disilicide, and at least one secondary component which is a refractory silicide. The silicon carbide dispersant may be in the form of VLS whiskers, VS whiskers, or submicron powder or a mixture of these forms.

  15. Molybdenum disilicide alloy matrix composite

    DOEpatents

    Petrovic, John J.; Honnell, Richard E.; Gibbs, W. Scott

    1990-01-01

    Compositions of matter consisting of matrix matrials having silicon carbide dispersed throughout them and methods of making the compositions. A matrix material is an alloy of an intermetallic compound, molybdenum disilicide, and at least one secondary component which is a refractory silicide. The silicon carbide dispersant may be in the form of VLS whiskers, VS whiskers, or submicron powder or a mixture of these forms.

  16. Staggered chiral random matrix theory

    SciTech Connect

    Osborn, James C.

    2011-02-01

    We present a random matrix theory for the staggered lattice QCD Dirac operator. The staggered random matrix theory is equivalent to the zero-momentum limit of the staggered chiral Lagrangian and includes all taste breaking terms at their leading order. This is an extension of previous work which only included some of the taste breaking terms. We will also present some results for the taste breaking contributions to the partition function and the Dirac eigenvalues.

  17. Magnet Technology for Power Converters: Nanocomposite Magnet Technology for High Frequency MW-Scale Power Converters

    SciTech Connect

    2012-02-27

    Solar ADEPT Project: CMU is developing a new nanoscale magnetic material that will reduce the size, weight, and cost of utility-scale PV solar power conversion systems that connect directly to the grid. Power converters are required to turn the energy that solar power systems create into useable energy for the grid. The power conversion systems made with CMU’s nanoscale magnetic material have the potential to be 150 times lighter and significantly smaller than conventional power conversion systems that produce similar amounts of power.

  18. Oriented Matrix Promotes Directional Tubulogenesis

    PubMed Central

    Soucy, Patricia A.; Hoh, Maria; Heinz, Will; Hoh, Jan; Romer, Lewis

    2014-01-01

    Detailed control over the structural organization of scaffolds and engineered tissue constructs is a critical need in the quest to engineer functional tissues using biomaterials. This work presents a new approach to the spatial direction of endothelial tubulogenesis. Micropatterned fibronectin substrates were used to control lung fibroblast adhesion and growth and the subsequent deposition of fibroblast-derived matrix during culture. The fibroblast-derived matrix produced on the micropatterned substrates was tightly oriented by these patterns, with an average variation of only 8.5°. Further, regions of this oriented extracellular matrix provided directional control of developing endothelial tubes to within 10° of the original micropatterned substrate design. Endothelial cells seeded directly onto the micropatterned substrate did not form tubes. A metric for matrix anisotropy showed a relationship between the fibroblast-derived matrix and the endothelial tubes that were subsequently developed on the same micropatterns with a resulting aspect ratio over 1.5 for endothelial tubulogenesis. Micropatterns in “L” and “Y” shapes were used to direct endothelial tubes to turn and branch with the same level of precision. These data demonstrate that anisotropic fibroblast-derived matrices instruct the alignment and shape of endothelial tube networks, thereby introducing an approach that could be adapted for future design of microvascular implants featuring organ-specific natural matrix that patterns microvascular growth. PMID:25219769

  19. A study of Schwarz converters for nuclear powered spacecraft

    NASA Technical Reports Server (NTRS)

    Stuart, Thomas A.; Schwarze, Gene E.

    1987-01-01

    High power space systems which use low dc voltage, high current sources such as thermoelectric generators, will most likely require high voltage conversion for transmission purposes. This study considers the use of the Schwarz resonant converter for use as the basic building block to accomplish this low-to-high voltage conversion for either a dc or an ac spacecraft bus. The Schwarz converter has the important assets of both inherent fault tolerance and resonant operation; parallel operation in modular form is possible. A regulated dc spacecraft bus requires only a single stage converter while a constant frequency ac bus requires a cascaded Schwarz converter configuration. If the power system requires constant output power from the dc generator, then a second converter is required to route unneeded power to a ballast load.

  20. Optimisation Of a Magnetostrictive Wave Energy Converter

    NASA Astrophysics Data System (ADS)

    Mundon, T. R.; Nair, B.

    2014-12-01

    Oscilla Power, Inc. (OPI) is developing a patented magnetostrictive wave energy converter aimed at reducing the cost of grid-scale electricity from ocean waves. Designed to operate cost-effectively across a wide range of wave conditions, this will be the first use of reverse magnetostriction for large-scale energy production. The device architecture is a straightforward two-body, point absorbing system that has been studied at length by various researchers. A large surface float is anchored to a submerged heave (reaction) plate by multiple taut tethers that are largely made up of discrete, robust power takeoff modules that house the magnetostrictive generators. The unique generators developed by OPI utilize the phenomenon of reverse magnetostriction, which through the application of load to a specific low cost alloy, can generate significant magnetic flux changes, and thus create power through electromagnetic induction. Unlike traditional generators, the mode of operation is low-displacement, high-force, high damping which in combination with the specific multi-tether configuration creates some unique effects and interesting optimization challenges. Using an empirical approach with a combination of numerical tools, such as ORCAFLEX, and physical models, we investigated the properties and sensitivities of this system arrangement, including various heave plate geometries, with the overall goal of identifying the mass and hydrodynamic parameters required for optimum performance. Furthermore, through a detailed physical model test program at the University of New Hampshire, we were able to study in more detail how the heave plate geometry affects the drag and added mass coefficients. In presenting this work we will discuss how alternate geometries could be used to optimize the hydrodynamic parameters of the heave plate, allowing maximum inertial forces in operational conditions, while simultaneously minimizing the forces generated in extreme waves. This presentation

  1. Calculating the GONG Leakage Matrix

    NASA Astrophysics Data System (ADS)

    Hill, F.; Howe, R.

    Since spherical harmonics do not form a complete orthonormal basis set over a portion of a sphere, helioseismic spectra computed for a specific target mode with degree ellt and azimuthal degree mt also contain modes with nearby ell'' and m''. These spatial leaks greatly increase the complexity of the observed spectrum, complicating the spectral fitting and degrading the resulting mode parameter estimates. This is particularly true where the target mode and the leaks have similar frequencies. Some strategies for fitting helioseismic spectra explicitly include the leakage matrix which estimates the relative strength of a mode (ell'' and m'') in the spectrum at (ellt,mt). Since the fitting methods assume that the matrix is correct and apply it as a constraint, an inaccurate matrix introduces systematic errors in the estimated mode parameters. It is thus important to have as accurate a matrix as possible. Here we report on the calculation of the leakage matrix for the GONG observations. The matrix elements are essentially the integrals (over the observed portion of the solar surface) of the crossproducts of the two spherical harmonics. However, several effects have been included to increase the accuracy of the matrix. These include the projection factor of the observable (velocity, intensity, modulation), the spatial apodization applied to the data, the finite rectangular pixel dimensions of the observations, and possible errors in the estimated image geometry. Other factors to be incorporated are the observed MTF, the merging of the GONG images, and the horizontal components of the oscillatory velocity field. We will compare the latest calculation with the observed spectrum and assess the relative importance of the input factors. We will also compare the leakage matrices for velocity and intensity to estimate their contribution to the large apparent differences in the helioseismic spectra obtained from these observables.

  2. The Astrobiology Matrix and the "Drake Matrix" in Education

    NASA Technical Reports Server (NTRS)

    Mizser, A.; Kereszturi, A.

    2003-01-01

    We organized astrobiology lectures in the Eotvos Lorand University of Sciences and the Polaris Observatory in 2002. We present here the "Drake matrix" for the comparison of the astrobiological potential of different bodies [1], and astrobiology matrix for the visualization of the interdisciplinary connections between different fields of astrobiology. Conclusion: In Hungary it is difficult to integrate astrobiology in the education system but the great advantage is that it can connect different scientific fields and improve the view of students. We would like to get in contact with persons and organizations who already have experience in the education of astrobiology.

  3. Analysis of series resonant converter with series-parallel connection

    NASA Astrophysics Data System (ADS)

    Lin, Bor-Ren; Huang, Chien-Lan

    2011-02-01

    In this study, a parallel inductor-inductor-capacitor (LLC) resonant converter series-connected on the primary side and parallel-connected on the secondary side is presented for server power supply systems. Based on series resonant behaviour, the power metal-oxide-semiconductor field-effect transistors are turned on at zero voltage switching and the rectifier diodes are turned off at zero current switching. Thus, the switching losses on the power semiconductors are reduced. In the proposed converter, the primary windings of the two LLC converters are connected in series. Thus, the two converters have the same primary currents to ensure that they can supply the balance load current. On the output side, two LLC converters are connected in parallel to share the load current and to reduce the current stress on the secondary windings and the rectifier diodes. In this article, the principle of operation, steady-state analysis and design considerations of the proposed converter are provided and discussed. Experiments with a laboratory prototype with a 24 V/21 A output for server power supply were performed to verify the effectiveness of the proposed converter.

  4. Matrix factorizations and elliptic fibrations

    NASA Astrophysics Data System (ADS)

    Omer, Harun

    2016-09-01

    I use matrix factorizations to describe branes at simple singularities of elliptic fibrations. Each node of the corresponding Dynkin diagrams of the ADE-type singularities is associated with one indecomposable matrix factorization which can be deformed into one or more factorizations of lower rank. Branes with internal fluxes arise naturally as bound states of the indecomposable factorizations. Describing branes in such a way avoids the need to resolve singularities. This paper looks at gauge group breaking from E8 fibers down to SU (5) fibers due to the relevance of such fibrations for local F-theory GUT models. A purpose of this paper is to understand how the deformations of the singularity are understood in terms of its matrix factorizations. By systematically factorizing the elliptic fiber equation, this paper discusses geometries which are relevant for building semi-realistic local models. In the process it becomes evident that breaking patterns which are identical at the level of the Kodaira type of the fibers can be inequivalent at the level of matrix factorizations. Therefore the matrix factorization picture supplements information which the conventional less detailed descriptions lack.

  5. Relativistic Dipole Matrix Element Zeros

    NASA Astrophysics Data System (ADS)

    Lajohn, L. A.; Pratt, R. H.

    2002-05-01

    There is a special class of relativistic high energy dipole matrix element zeros (RZ), whose positions with respect to photon energy ω , only depend on the bound state l quantum number according to ω^0=mc^2/(l_b+1) (independent of primary quantum number n, nuclear charge Z, central potential V and dipole retardation). These RZ only occur in (n,l_b,j_b)arrow (ɛ , l_b+1,j_b) transitions such as ns_1/2arrow ɛ p_1/2; np_3/2arrow ɛ d_3/2: nd_5/2arrow ɛ f_5/2 etc. The nonrelativistic limit of these matrix elements can be established explicitly in the Coulomb case. Within the general matrix element formalism (such as that in [1]); when |κ | is substituted for γ in analytic expressions for matrix elements, the zeros remain, but ω^0 now becomes dependent on n and Z. When the reduction to nonrelativistic form is completed by application of the low energy approximation ω mc^2 mc^2, the zeros disappear. This nonzero behavior was noted in nonrelativistic dipole Coulomb matrix elements by Fano and Cooper [2] and later proven by Oh and Pratt[3]. (J. H. Scofield, Phys. Rev. A 40), 3054 (1989 (U. Fano and J. W. Cooper, Rev. Mod. Phys. 40), 441 (1968). (D. Oh and R. H. Pratt, Phys. Rev. A 34), 2486 (1986); 37, 1524 (1988); 45, 1583 (1992).

  6. Terbium luminescence in alumina xerogel fabricated in porous anodic alumina matrix under various excitation conditions

    SciTech Connect

    Gaponenko, N. V.; Kortov, V. S.; Orekhovskaya, T. I.; Nikolaenko, I. A.; Pustovarov, V. A.; Zvonarev, S. V.; Slesarev, A. I.; Prislopski, S. Ya.

    2011-07-15

    Terbium-doped alumina xerogel layers are synthesized by the sol-gel method in pores of a porous anodic alumina film 1 {mu}m thick with a pore diameter of 150-180 nm; the film is grown on a silicon substrate. The fabricated structures exhibit terbium photoluminescence with bands typical of trivalent terbium terms. Terbium X-ray luminescence with the most intense band at 542 nm is observed for the first time for such a structure. Morphological analysis of the structure by scanning electron microscopy shows the presence of xerogel clusters in pore channels, while the main pore volume remains unfilled and pore mouths remain open. The data obtained confirm the promising applications of fabricated structures for developing matrix converters of X-rays and other ionizing radiations into visible light. The possibilities of increasing luminescence intensity in the matrix converter are discussed.

  7. Ultrathin flexible terahertz polarization converter based on metasurfaces.

    PubMed

    Mo, Weicheng; Wei, Xuli; Wang, Kejia; Li, Yao; Liu, Jinsong

    2016-06-13

    We present a method to design and fabricate a kind of converters based on flexible metasurfaces which can change the polarization state of an incident terahertz beam. The metasurface consists of a two-dimensional array of rectangular metallic antennas that can abruptly change the phase of the incoming terahertz beam. Experimentally demonstrated half-wave plates generate 0.1 THz beam with a π/2 polarization rotation. By slightly changing the structure of the converter, an elliptically or circularly polarized beam is expected to be obtained. These flexible terahertz converters may have many potential applications in terahertz technology.

  8. Large bandwidth mode order converter by differential waveguides.

    PubMed

    Oner, B B; Üstün, K; Kurt, H; Okyay, A K; Turhan-Sayan, G

    2015-02-01

    In this article, we propose a large bandwidth mode-order converter design by dielectric waveguides with equal lengths but different cross-sectional areas. The efficient conversion between even and odd modes is verified by inducing required phase difference between the equal length waveguides of different widths. Y-junctions are composed of both tapered mode splitter and combiner to connect mono-mode waveguide to multi-mode waveguide. The converted mode profiles at the output port show that the device operates successfully at designed wavelengths with wide bandwidth. This study provides a novel technique to implement compact mode order converters and direction selective/sensitive photonic structures.

  9. Ultrathin flexible terahertz polarization converter based on metasurfaces.

    PubMed

    Mo, Weicheng; Wei, Xuli; Wang, Kejia; Li, Yao; Liu, Jinsong

    2016-06-13

    We present a method to design and fabricate a kind of converters based on flexible metasurfaces which can change the polarization state of an incident terahertz beam. The metasurface consists of a two-dimensional array of rectangular metallic antennas that can abruptly change the phase of the incoming terahertz beam. Experimentally demonstrated half-wave plates generate 0.1 THz beam with a π/2 polarization rotation. By slightly changing the structure of the converter, an elliptically or circularly polarized beam is expected to be obtained. These flexible terahertz converters may have many potential applications in terahertz technology. PMID:27410377

  10. Designing A Mode Converter For Use With A Gyrotron

    NASA Technical Reports Server (NTRS)

    Hoppe, Daniel J.

    1995-01-01

    Report describes process of designing corrugated, circular-cross-section length of waveguide converting input electromagnetic radiation at frequency of 34.5 GHz in TM(11) mode to output radiation in HE(11) mode. TM(11)-mode input radiation supplied by gyrotron generating continuous-wave power of 200 kW at 34.5 GHz in TE(01) mode followed by TE(01)-to-TM(11) mode converter. Together, gyrotron and mode converters constitute prototype high-power transmitter for long-distance free-space communication.

  11. Parallel Stirling Converters Being Developed for Spacecraft Onboard Power

    NASA Technical Reports Server (NTRS)

    Thieme, Lanny G.

    1999-01-01

    Stirling Technology Co., as part of a NASA Lewis Research Center Phase II Small Business Innovation Research contract, has successfully demonstrated paralleling two thermodynamically independent Stirling converters. A system of four Stirling converters is being developed by NASA and the Department of Energy as an alternative high-efficiency radioisotope power source for spacecraft onboard electric power for NASA deep space missions. The high Stirling efficiency, exceeding 20 percent for this application, will greatly reduce the necessary isotope inventory in comparison to the current radioisotope thermoelectric generators (RTG s), significantly reducing mission cost and risk. Stirling is the most developed converter option of the advanced power technologies under consideration.

  12. Weather satellite picture receiving stations, APT digital scan converter

    NASA Technical Reports Server (NTRS)

    Vermillion, C. H.; Kamowski, J. C.

    1975-01-01

    The automatic picture transmission digital scan converter is used at ground stations to convert signals received from scanning radiometers to data compatible with ground equipment designed to receive signals from vidicons aboard operational meteorological satellites. Information necessary to understand the circuit theory, functional operation, general construction and calibration of the converter is provided. Brief and detailed descriptions of each of the individual circuits are included, accompanied by a schematic diagram contained at the end of each circuit description. Listings of integral parts and testing equipment required as well as an overall wiring diagram are included. This unit will enable the user to readily accept and process weather photographs from the operational meteorological satellites.

  13. An optoelectronic interferometric analog-to-digital converter

    NASA Astrophysics Data System (ADS)

    Evtikhiev, N. N.; Karinskii, S. S.; Mirovitskii, D. I.; Popkov, V. T.

    1987-02-01

    A high-speed optoelectronic analog-to-digital (A/D) converter utilizing waveguide interferometric modulators (WIMs) is analyzed in detail. A mathematical model is proposed which describes the relationship between the characteristics of WIMs in LiNbO3 and their manufacturing conditions. The requirements placed on the parameters of the manufacturing process for obtaining the desired modulator and optoelectronic A/D converter characteristics are determined. Results are presented of the R&D of a 4-bit optoelectronic A/D converter with a conversion rate of 160 MBit/s.

  14. Design and operation of a thermionic converter in air

    SciTech Connect

    Horner, M.H.; Begg, L.L.; Smith, J.N. Jr.; Geller, C.B.; Kallnowski, J.E.

    1995-01-01

    An electrically heated thermionic converter has been designed, built and successfully tested in air. Several unique features were incorporated in this converter: an integral cesium reservoir, innovative ceramic-to-metal seals, a heat rejection system coupling the collector to a low temperature heat sink and an innovative cylindrical heater filament. The converter was operated for extended periods of time with the emitter at about 1900 K. the collector at about 700 K, and a power density of over 2 w(e)/sq. cm. Input power transients were run between 50% and 100% thermal power, at up to 1% per second, without instabilities in performance.

  15. Choosing to convert to critical access hospital status.

    PubMed

    Dalton, Kathleen; Slifkin, Rebecca; Poley, Stephanie; Fruhbeis, Melissa

    2003-01-01

    The authors profile facilities converting to critical access hospitals (CAHs) from 1998-2000, comparing characteristics of their communities, operations, and finances to those of other small rural providers. Counties where CAHs are located are more sparsely populated, but do not have substantially different sociodemographic profiles than other rural counties. Converting hospitals' acute daily census averaged well below the statutory limit of 15, but over one-half reduced unused bed capacity to meet CAH size limitations. The average case-mix adjusted Medicare cost per case was 16-percent higher for CAH converters than for other small hospitals and their financial ratios were substantially worse, although many other operating characteristics were similar.

  16. Matrix Formalism of Synchrobetatron Coupling

    SciTech Connect

    Huang, Xiaobiao; /SLAC

    2006-10-06

    In this paper we present a complete linear synchrobetatron coupling formalism by studying the transfer matrix which describes linear horizontal and longitudinal motions. With the technique established in the linear horizontal-vertical coupling study [D. Sagan and D. Rubin, Phys. Rev. ST Accel. Beams 2, 074001 (1999)], we found a transformation to block diagonalize the transfer matrix and decouple the betatron motion and the synchrotron motion. By separating the usual dispersion term from the horizontal coordinate first, we were able to obtain analytic expressions of the transformation under reasonable approximations. We also obtained the perturbations to the betatron tune and the Courant-Snyder functions. The closed orbit changes due to finite energy gains at rf cavities and radiation energy losses were also studied by the 5 x 5 extended transfer matrix with the fifth column describing kicks in the 4-dimension phase space.

  17. Extracellular matrix in ovarian follicles.

    PubMed

    Rodgers, R J; Irving-Rodgers, H F; van Wezel, I L

    2000-05-25

    A lot is known about the control of the development of ovarian follicles by growth factors and hormones, but less is known about the roles of extracellular matrix in the control of follicular growth and development. In this review we focus on the specialized extracellular matrix of the basal laminas that are present in ovarian follicles. These include the follicular basal lamina itself, the Call-Exner bodies of the membrana granulosa, the subendothelial and arteriole smooth muscle basal laminas in the theca, and the basal lamina-like material of the thecal matrix. We discuss the evidence that during follicle development the follicular basal lamina changes in composition, that many of its components are produced by the granulosa cells, and that the follicular basal laminas of different follicles have different ultrastructural appearances, linked to the shape of the aligning granulosa cells. All these studies suggest that the follicular basal lamina is extremely dynamic during follicular development. PMID:10963877

  18. Matrix model approach to cosmology

    NASA Astrophysics Data System (ADS)

    Chaney, A.; Lu, Lei; Stern, A.

    2016-03-01

    We perform a systematic search for rotationally invariant cosmological solutions to toy matrix models. These models correspond to the bosonic sector of Lorentzian Ishibashi, Kawai, Kitazawa and Tsuchiya (IKKT)-type matrix models in dimensions d less than ten, specifically d =3 and d =5 . After taking a continuum (or commutative) limit they yield d -1 dimensional Poisson manifolds. The manifolds have a Lorentzian induced metric which can be associated with closed, open, or static space-times. For d =3 , we obtain recursion relations from which it is possible to generate rotationally invariant matrix solutions which yield open universes in the continuum limit. Specific examples of matrix solutions have also been found which are associated with closed and static two-dimensional space-times in the continuum limit. The solutions provide for a resolution of cosmological singularities, at least within the context of the toy matrix models. The commutative limit reveals other desirable features, such as a solution describing a smooth transition from an initial inflation to a noninflationary era. Many of the d =3 solutions have analogues in higher dimensions. The case of d =5 , in particular, has the potential for yielding realistic four-dimensional cosmologies in the continuum limit. We find four-dimensional de Sitter d S4 or anti-de Sitter AdS4 solutions when a totally antisymmetric term is included in the matrix action. A nontrivial Poisson structure is attached to these manifolds which represents the lowest order effect of noncommutativity. For the case of AdS4 , we find one particular limit where the lowest order noncommutativity vanishes at the boundary, but not in the interior.

  19. Phase substitution of spare converter for a failed one of parallel phase staggered converters

    NASA Technical Reports Server (NTRS)

    Mclyman, W. T.; Wester, G. W. (Inventor)

    1977-01-01

    Failure detection and substitution of a spare module is provided in a system having a plurality of phase staggered modules connected in parallel to deliver regulated voltage from an unregulated source. Phase control signals applied to the active converter modules are applied to the spare module through NOR gates associated with and disabled by the power output of respective modules such that failure of any one enables its phase control signal to be applied to the spare module, thus controlling the spare module to operate in the phase position of the failed module. A NAND gate detects when any one active module fails and enables a gate in the spare module, thus activating the spare module.

  20. Trapping on demand: External regulation of excitation energy transfer in a photoswitchable smart matrix

    NASA Astrophysics Data System (ADS)

    Schmidt, R.; Pärs, M.; Weller, T.; Thelakkat, M.; Köhler, J.

    2014-01-01

    A thin film of polystyrene has been doped with small amounts of dithienylcyclopentene (DCP) based molecular switches and perylene bisimide (PBI) chromophores to obtain a photoswitchable smart matrix. The photochromic DCP can be converted by light between two bistable conformations and thereby changes the energetic position of its lowest excited singlet state. We exploit this feature to regulate the transfer of excitation energy between PBI and DCP as a function of the externally controllable illumination conditions in such a blend.

  1. Spectral decomposition of a matrix using the generalized sign matrix

    NASA Technical Reports Server (NTRS)

    Denman, E. D.; Leyva-Ramos, J.

    1981-01-01

    An algorithm for spectral decomposition is presented which does not require knowledge of eigenvalues and eigenvectors. A set of eigenprojectors are defined which covers the entire spectrum of a matrix, and special attention is given to the projection on the zero eigenvalue. Some useful applications are discussed in the paper.

  2. The HDTV digital audio matrix

    NASA Astrophysics Data System (ADS)

    Mason, A. J.

    Multichannel sound systems are being studied as part of the Eureka 95 and Radio-communication Bureau TG10-1 investigations into high definition television. One emerging sound system has five channels; three at the front and two at the back. This raises some compatibility issues. The listener might have only, say, two loudspeakers or the material to be broadcast may have fewer than five channels. The problem is how best to produce a set of signals to be broadcast, which is suitable for all listeners, from those that are available. To investigate this area, a device has been designed and built which has six input channels and six output channels. Each output signal is a linear combination of the input signals. The inputs and outputs are in AES/EBU digital audio format using BBC-designed AESIC chips. The matrix operation, to produce the six outputs from the six inputs, is performed by a Motorola DSP56001. The user interface and 'housekeeping' is managed by a T222 transputer. The operator of the matrix uses a VDU to enter sets of coefficients and a rotary switch to select which set to use. A set of analog controls is also available and is used to control operations other than the simple compatibility matrixing. The matrix has been very useful for simple tasks: mixing a stereo signal into mono, creating a stereo signal from a mono signal, applying a fixed gain or attenuation to a signal, exchanging the A and B channels of an AES/EBU bitstream, and so on. These are readily achieved using simple sets of coefficients. Additions to the user interface software have led to several more sophisticated applications which still consist of a matrix operation. Different multichannel panning laws have been evaluated. The analog controls adjust the panning; the audio signals are processed digitally using a matrix operation. A digital SoundField microphone decoder has also been implemented. matrix operation, the analog controls being used to adjust the

  3. Shrinkage estimation of the realized relationship matrix

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The additive relationship matrix plays an important role in mixed model prediction of breeding values. For genotype matrix X (loci in columns), the product XX' is widely used as a realized relationship matrix, but the scaling of this matrix is ambiguous. Our first objective was to derive a proper ...

  4. Non-synchronous control of self-oscillating resonant converters

    DOEpatents

    Glaser, John Stanley; Zane, Regan Andrew

    2002-01-01

    A self-oscillating switching power converter has a controllable reactance including an active device connected to a reactive element, wherein the effective reactance of the reactance and the active device is controlled such that the control waveform for the active device is binary digital and is not synchronized with the switching converter output frequency. The active device is turned completely on and off at a frequency that is substantially greater than the maximum frequency imposed on the output terminals of the active device. The effect is to vary the average resistance across the active device output terminals, and thus the effective output reactance, thereby providing converter output control, while maintaining the response speed of the converter.

  5. INTERIOR OF BESSEMER BUILDING. LOOKING EAST. PLATFORM WHERE CONVERTERS STOOD. ...

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

    INTERIOR OF BESSEMER BUILDING. LOOKING EAST. PLATFORM WHERE CONVERTERS STOOD. - Jones & Laughlin Steel Corporation, Pittsburgh Works, Morgan Billet Mill Engine, 550 feet north of East Carson Street, opposite South Twenty-seventh Street, Pittsburgh, Allegheny County, PA

  6. 76. Photocopied August 1978. STANLEY ROTARY CONVERTER, PENSTOCK NO. 41, ...

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

    76. Photocopied August 1978. STANLEY ROTARY CONVERTER, PENSTOCK NO. 41, WITH SOME OF THE STANLEY TRANSFORMERS IN THE BACKGROUND. (442) - Michigan Lake Superior Power Company, Portage Street, Sault Ste. Marie, Chippewa County, MI

  7. Wide-converter lens design for a pico projector.

    PubMed

    Pan, Jui-Wen; Chen, Yi-Chin

    2014-12-20

    In this paper, we propose a concept for the design of a 0.702× wide-converter lens for a 0.3 in. digital micromirror device. This 0.702× wide-converter lens is capable of enlarging the size of the original projected image at the same projection distance. This 0.702× wide-converter lens is attached in front of the projection lens of a pico projector (PP). Compared with the projection lens of a PP without the 0.702× wide-converter lens, there is an increase in the size of the original projected image of 42.4% at the same projection distance. In other words, there is a saving of projection distance of 29.78% to obtain a projected image of the same size.

  8. Laser-to-electricity energy converter for short wavelengths

    NASA Technical Reports Server (NTRS)

    Stirn, R. J.; Yeh, Y. C. M.

    1975-01-01

    Short-wavelength energy converter can be made using Schottky barrier structure. It has wider band gap than p-n junction silicon semiconductors, and thus it has improved response at wavelengths down to and including ultraviolet region.

  9. Elimination of current spikes in buck power converters

    NASA Technical Reports Server (NTRS)

    Mclyman, W. T. (Inventor)

    1981-01-01

    Current spikes in a buck power converter due to commutating diode turn-off time are eliminated by using a tapped inductor in the converter with the tap connected to the switching transistor. The commutating diode is not in the usual place, but is instead connected to conduct current from one end of the tapped inductor remote from the load during the interval in which the transistor is not conducting. In the case of a converter having a center-tapped (primary and secondary) transformer between two switching power transistors operated in a push-pull mode and two rectifying diodes in the secondary circuit, current spikes due to transformer saturation are also eliminated by using a tapped inductor in the converter with the tap connected to the rectifying diodes and a diode connected to conduct current from one end of the tapped inductor remote from the load during the interval in which the transistors are not conducting.

  10. 40 CFR 89.317 - NOX converter check.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) CONTROL OF EMISSIONS FROM NEW AND IN-USE NONROAD COMPRESSION-IGNITION ENGINES Emission Test Equipment..., the chemiluminescent oxides of nitrogen analyzer shall be checked for NO2 to NO converter...

  11. Burnout sensitivity of power MOSFETs operating in a switching converter

    NASA Astrophysics Data System (ADS)

    Tastet, P.; Garnier, J.; Constans, H.; Tizon, A. H.

    1994-06-01

    Heavy ion tests of a switching converter using power MOSFETs have allowed us to identify the main parameters which affect the burnout sensitivity of these components. The differences between static and dynamic conditions are clarified in this paper.

  12. Converting molecular information of redox coenzymes via self-assembly.

    PubMed

    Morikawa, Masa-aki; Kimizuka, Nobuo

    2012-11-21

    β-Nicotinamide adenine dinucleotide (NAD(+)) and its reduced form NADH specifically interact with a cyanine dye in aqueous media, giving distinct spectral and nanostructural characteristics to which molecular information of constituent coenzymes are converted via self-assembly.

  13. East yard, north elevation of car department tool house (converted ...

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

    East yard, north elevation of car department tool house (converted from express car). - Chesapeake & Ohio Railroad, Thurmond Yards, East side New River, mouths of Arbuckle & Dunlop Circles, Thurmond, Fayette County, WV

  14. Converting Sunlight to Mechanical Energy: A Polymer Example of Entropy.

    ERIC Educational Resources Information Center

    Mathias, Lon J.

    1987-01-01

    This experiment/demonstration provides elementary through high school science students with hands-on experience with polymer entropy. Construction of a simple machine for converting light into mechanical energy is described. (RH)

  15. Liquid Nitrogen Temperature Operation of a Switching Power Converter

    NASA Technical Reports Server (NTRS)

    Ray, Biswajit; Gerber, Scott S.; Patterson, Richard L.; Myers, Ira T.

    1995-01-01

    The performance of a 42/28 V, 175 W, 50 kHz pulse-width modulated buck dc/dc switching power converter at liquid nitrogen temperature (LNT) is compared with room temperature operation. The power circuit as well as the control circuit of the converter, designed with commercially available components, were operated at LNT and resulted in a slight improvement in converter efficiency. The improvement in power MOSFET operation was offset by deteriorating performance of the output diode rectifier at LNT. Performance of the converter could be further improved at low temperatures by using only power MOSFET's as switches. The use of a resonant topology will further improve the circuit performance by reducing the switching noise and loss.

  16. Assembly processor program converts symbolic programming language to machine language

    NASA Technical Reports Server (NTRS)

    Pelto, E. V.

    1967-01-01

    Assembly processor program converts symbolic programming language to machine language. This program translates symbolic codes into computer understandable instructions, assigns locations in storage for successive instructions, and computer locations from symbolic addresses.

  17. 8. INTERIOR VIEW, SHOWING CONVERTED STAND FOR COMPRESSOR RESEARCH. ...

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

    8. INTERIOR VIEW, SHOWING CONVERTED STAND FOR COMPRESSOR RESEARCH. - Wright-Patterson Air Force Base, Area B, Building No. 20A, Propeller Test Complex, Seventh Street, from E to G Streets, Dayton, Montgomery County, OH

  18. Translator program converts computer printout into braille language

    NASA Technical Reports Server (NTRS)

    Powell, R. A.

    1967-01-01

    Computer program converts print image tape files into six dot Braille cells, enabling a blind computer programmer to monitor and evaluate data generated by his own programs. The Braille output is printed 8 lines per inch.

  19. Converting baker's waste into alcohol. Revised final progress report

    SciTech Connect

    Halsey, R.; Wilson, P.B.

    1982-01-01

    All types of baker's waste (including waste from candy manufacturers) can be converted into alcohol to be used as a fuel. All types of waste at any stage in process can be converted, such as: basic ingredients (including floor sweepings); dry mixes (including floor sweepings); dough at any stage; partially or fully cooked products; and day old returned products. The basic steps are the same, only the initial preparation will vary slightly. The variation will be: amount of water to be added and amount and type of nutrients (if any) to be added. The basic steps are: slurrying, liquefying to put starch into liquid state, saccharifying to convert starch into fermentable sugars, fermentation to convert sugars into alcohol, and distillation to separate the alcohol from the mash. Each step is discussed in detail along with problems that may arise. Directions are given and materials (enzymes, yeast, etc.) and equipment are descibed briefly.

  20. Method for converting uranium oxides to uranium metal

    DOEpatents

    Duerksen, Walter K.

    1988-01-01

    A process is described for converting scrap and waste uranium oxide to uranium metal. The uranium oxide is sequentially reduced with a suitable reducing agent to a mixture of uranium metal and oxide products. The uranium metal is then converted to uranium hydride and the uranium hydride-containing mixture is then cooled to a temperature less than -100.degree. C. in an inert liquid which renders the uranium hydride ferromagnetic. The uranium hydride is then magnetically separated from the cooled mixture. The separated uranium hydride is readily converted to uranium metal by heating in an inert atmosphere. This process is environmentally acceptable and eliminates the use of hydrogen fluoride as well as the explosive conditions encountered in the previously employed bomb-reduction processes utilized for converting uranium oxides to uranium metal.

  1. 20. VIEW OF TENNIS COURTS LOOKING SOUTH, WITH CONVERTED BASKETBALL ...

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

    20. VIEW OF TENNIS COURTS LOOKING SOUTH, WITH CONVERTED BASKETBALL COURT IN FOREGROUND. - Loring Air Force Base, Alert Area, Southeastern portion of base, east of southern end of runway, Limestone, Aroostook County, ME

  2. The APA Style Converter: a Web-based interface for converting articles to APA style for publication.

    PubMed

    Li, Ping; Cunningham, Krystal

    2005-05-01

    The APA Style Converter is a Web-based tool with which authors may prepare their articles in APA style according to the APA Publication Manual (5th ed.). The Converter provides a user-friendly interface that allows authors to copy and paste text and upload figures through the Web, and it automatically converts all texts, references, and figures to a structured article in APA style. The output is saved in PDF or RTF format, ready for either electronic submission or hardcopy printing.

  3. The APA Style Converter: a Web-based interface for converting articles to APA style for publication.

    PubMed

    Li, Ping; Cunningham, Krystal

    2005-05-01

    The APA Style Converter is a Web-based tool with which authors may prepare their articles in APA style according to the APA Publication Manual (5th ed.). The Converter provides a user-friendly interface that allows authors to copy and paste text and upload figures through the Web, and it automatically converts all texts, references, and figures to a structured article in APA style. The output is saved in PDF or RTF format, ready for either electronic submission or hardcopy printing. PMID:16171194

  4. Sealing and anti-corrosive action of tannin rust converters

    SciTech Connect

    Gust, J.; Bobrowicz, J. )

    1993-01-01

    A possibility of the application of mercury porosimetry in the investigation on porosity in corrosion products of the carbon steel along with the degree of sealing by the use of tannin rust converters is presented. The effect of the atmospheric humidity on the rust conversion including the time of that conversion on the degree of rust sealing is discussed. The results of the corrosion investigation of carbon steel covered with a layer of the rust converted with tannin-containing agents are presented.

  5. Small-signal model for the series resonant converter

    NASA Technical Reports Server (NTRS)

    King, R. J.; Stuart, T. A.

    1985-01-01

    The results of a previous discrete-time model of the series resonant dc-dc converter are reviewed and from these a small signal dynamic model is derived. This model is valid for low frequencies and is based on the modulation of the diode conduction angle for control. The basic converter is modeled separately from its output filter to facilitate the use of these results for design purposes. Experimental results are presented.

  6. An Inexpensive Commercially Available Analog-to-Digital Converter

    NASA Astrophysics Data System (ADS)

    Breton, Gary W.

    2000-02-01

    The use of an inexpensive analog-to-digital converter for interfacing gas chromatographs to computers in a teaching laboratory environment is described. Raw data may be read, processed, and printed from software supplied with the converter to afford chromatograms of acceptable quality. Alternatively, data may be imported into readily available commercial spreadsheet programs, which allows for easy analysis and production of more attractive chromatograms.

  7. Charge Resolution of the Silicon Matrix of the ATIC Experiment

    NASA Technical Reports Server (NTRS)

    Zatsepin, V. I.; Adams, J. H., Jr.; Ahn, H. S.; Bashindzhagyan, G. L.; Batkov, K. E.; Case, G.; Christl, M.; Ganel, O.; Fazely, A. R.; Ganel, O.; Six, N. Frank (Technical Monitor)

    2002-01-01

    ATIC (Advanced Thin Ionization Calorimeter) is a balloon borne experiment designed to measure the cosmic ray composition for elements from hydrogen to iron and their energy spectra from approx.50 GeV to near 100 TeV. It consists of a Si-matrix detector to determine the charge of a CRT particle, a scintillator hodoscope for tracking, carbon interaction targets and a fully active BGO calorimeter. ATIC had its first flight from McMurdo, Antarctica from 28/12/2000 to 13/01/2001. The ATIC flight collected approximately 25 million events. The silicon matrix of the ATIC spectrometer is designed to resolve individual elements from proton to iron. To provide this resolution careful calibration of each pixel of the silicon matrix is required. Firstly, for each electronic channel of the matrix the pedestal value was subtracted taking into account its drift during the flight. The muon calibration made before the flight was used then to convert electric signals (in ADC channel number) to energy deposits in each pixel. However, the preflight muon calibration was not accurate enough for the purpose, because of lack of statistics in each pixel. To improve charge resolution the correction was done for the position of Helium peak in each pixel during the flight . The other way to set electric signals in electronics channels of the Si-matrix to one scale was correction for electric channel gains accurately measured in laboratory. In these measurements it was found that small different nonlinearities for different channels are present in the region of charge Z > 20. The correction for these non-linearities was not done yet. In linear approximation the method provides practically the same resolution as muon calibration plus He-peak correction. For searching a pixel with the signal of primary particle an indication from the cascade in the calorimeter was used. For this purpose a trajectory was reconstructed using weight centers of energy deposits in BGO layers. The point of intersection

  8. Why Flavins Are not Competitors of Chlorophyll in the Evolution of Biological Converters of Solar Energy

    PubMed Central

    Kritsky, Mikhail S.; Telegina, Taisiya A.; Vechtomova, Yulia L.; Buglak, Andrey A.

    2013-01-01

    Excited flavin molecules can photocatalyze reactions, leading to the accumulation of free energy in the products, and the data accumulated through biochemical experiments and by modeling prebiological processes suggest that flavins were available in the earliest stages of evolution. Furthermore, model experiments have shown that abiogenic flavin conjugated with a polyamino acid matrix, a pigment that photocatalyzes the phosphorylation of ADP to form ATP, could have been present in the prebiotic environment. Indeed, excited flavin molecules play key roles in many photoenzymes and regulatory photoreceptors, and the substantial structural differences between photoreceptor families indicate that evolution has repeatedly used flavins as chromophores for photoreceptor proteins. Some of these photoreceptors are equipped with a light-harvesting antenna, which transfers excitation energy to chemically reactive flavins in the reaction center. The sum of the available data suggests that evolution could have led to the formation of a flavin-based biological converter to convert light energy into energy in the form of ATP. PMID:23271372

  9. Bifurcation and chaos in high-frequency peak current mode Buck converter

    NASA Astrophysics Data System (ADS)

    Chang-Yuan, Chang; Xin, Zhao; Fan, Yang; Cheng-En, Wu

    2016-07-01

    Bifurcation and chaos in high-frequency peak current mode Buck converter working in continuous conduction mode (CCM) are studied in this paper. First of all, the two-dimensional discrete mapping model is established. Next, reference current at the period-doubling point and the border of inductor current are derived. Then, the bifurcation diagrams are drawn with the aid of MATLAB. Meanwhile, circuit simulations are executed with PSIM, and time domain waveforms as well as phase portraits in i L-v C plane are plotted with MATLAB on the basis of simulation data. After that, we construct the Jacobian matrix and analyze the stability of the system based on the roots of characteristic equations. Finally, the validity of theoretical analysis has been verified by circuit testing. The simulation and experimental results show that, with the increase of reference current I ref, the corresponding switching frequency f is approaching to low-frequency stage continuously when the period-doubling bifurcation happens, leading to the converter tending to be unstable. With the increase of f, the corresponding I ref decreases when the period-doubling bifurcation occurs, indicating the stable working range of the system becomes smaller. Project supported by the National Natural Science Foundation of China (Grant No. 61376029), the Fundamental Research Funds for the Central Universities, China, and the College Graduate Research and Innovation Program of Jiangsu Province, China (Grant No. SJLX15_0092).

  10. Bifurcation and chaos in high-frequency peak current mode Buck converter

    NASA Astrophysics Data System (ADS)

    Chang-Yuan, Chang; Xin, Zhao; Fan, Yang; Cheng-En, Wu

    2016-07-01

    Bifurcation and chaos in high-frequency peak current mode Buck converter working in continuous conduction mode (CCM) are studied in this paper. First of all, the two-dimensional discrete mapping model is established. Next, reference current at the period-doubling point and the border of inductor current are derived. Then, the bifurcation diagrams are drawn with the aid of MATLAB. Meanwhile, circuit simulations are executed with PSIM, and time domain waveforms as well as phase portraits in i L–v C plane are plotted with MATLAB on the basis of simulation data. After that, we construct the Jacobian matrix and analyze the stability of the system based on the roots of characteristic equations. Finally, the validity of theoretical analysis has been verified by circuit testing. The simulation and experimental results show that, with the increase of reference current I ref, the corresponding switching frequency f is approaching to low-frequency stage continuously when the period-doubling bifurcation happens, leading to the converter tending to be unstable. With the increase of f, the corresponding I ref decreases when the period-doubling bifurcation occurs, indicating the stable working range of the system becomes smaller. Project supported by the National Natural Science Foundation of China (Grant No. 61376029), the Fundamental Research Funds for the Central Universities, China, and the College Graduate Research and Innovation Program of Jiangsu Province, China (Grant No. SJLX15_0092).

  11. Ultra-wideband reflective polarization converter based on anisotropic metasurface

    NASA Astrophysics Data System (ADS)

    Wu, Jia-Liang; Lin, Bao-Qin; Da, Xin-Yu

    2016-08-01

    In this paper, we propose an ultra-wideband reflective linear cross-polarization converter based on anisotropic metasurface. Its unit cell is composed of a square-shaped resonator with intersectant diagonal and metallic ground sheet separated by dielectric substrate. Simulated results show that the converter can generate resonances at four frequencies under normal incident electromagnetic (EM) wave, leading to the bandwidth expansion of cross-polarization reflection. For verification, the designed polarization converter is fabricated and measured. The measured and simulated results agree well with each other, showing that the fabricated converter can convert x- or y-polarized incident wave into its cross polarized wave in a frequency range from 7.57 GHz to 20.46 GHz with a relative bandwidth of 91.2%, and the polarization conversion efficiency is greater than 90%. The proposed polarization converter has a simple geometry but an ultra wideband compared with the published designs, and hence possesses potential applications in novel polarization-control devices. Project supported by the National Natural Science Foundation of China (Grant Nos. 61471387, 61271250, and 61571460).

  12. 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.

  13. Bi-directional power control system for voltage converter

    DOEpatents

    Garrigan, Neil Richard; King, Robert Dean; Schwartz, James Edward

    1999-01-01

    A control system for a voltage converter includes: a power comparator for comparing a power signal on input terminals of the converter with a commanded power signal and producing a power comparison signal; a power regulator for transforming the power comparison signal to a commanded current signal; a current comparator for comparing the commanded current signal with a measured current signal on output terminals of the converter and producing a current comparison signal; a current regulator for transforming the current comparison signal to a pulse width modulator (PWM) duty cycle command signal; and a PWM for using the PWM duty cycle command signal to control electrical switches of the converter. The control system may further include: a command multiplier for converting a voltage signal across the output terminals of the converter to a gain signal having a value between zero (0) and unity (1), and a power multiplier for multiplying the commanded power signal by the gain signal to provide a limited commanded power signal, wherein power comparator compares the limited commanded power signal with the power signal on the input terminals.

  14. Bi-directional power control system for voltage converter

    DOEpatents

    Garrigan, N.R.; King, R.D.; Schwartz, J.E.

    1999-05-11

    A control system for a voltage converter includes: a power comparator for comparing a power signal on input terminals of the converter with a commanded power signal and producing a power comparison signal; a power regulator for transforming the power comparison signal to a commanded current signal; a current comparator for comparing the commanded current signal with a measured current signal on output terminals of the converter and producing a current comparison signal; a current regulator for transforming the current comparison signal to a pulse width modulator (PWM) duty cycle command signal; and a PWM for using the PWM duty cycle command signal to control electrical switches of the converter. The control system may further include: a command multiplier for converting a voltage signal across the output terminals of the converter to a gain signal having a value between zero (0) and unity (1), and a power multiplier for multiplying the commanded power signal by the gain signal to provide a limited commanded power signal, wherein power comparator compares the limited commanded power signal with the power signal on the input terminals. 10 figs.

  15. 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.

  16. Bidirectional converter for high-efficiency fuel cell powertrain

    NASA Astrophysics Data System (ADS)

    Fardoun, Abbas A.; Ismail, Esam H.; Sabzali, Ahmad J.; Al-Saffar, Mustafa A.

    2014-03-01

    In this paper, a new wide conversion ratio step-up and step-down converter is presented. The proposed converter is derived from the conventional Single Ended Primary Inductor Converter (SEPIC) topology and it is integrated with a capacitor-diode voltage multiplier, which offers a simple structure, reduced electromagnetic interference (EMI), and reduced semiconductors' voltage stresses. Other advantages include: continuous input and output current, extended step-up and step-down voltage conversion ratio without extreme low or high duty-cycle, simple control circuitry, and near-zero input and output ripple currents compared to other converter topologies. The low charging/discharging current ripple and wide gain features result in a longer life-span and lower cost of the energy storage battery system. In addition, the "near-zero" ripple capability improves the fuel cell durability. Theoretical analysis results obtained with the proposed structure are compared with other bi-direction converter topologies. Simulation and experimental results are presented to verify the performance of the proposed bi-directional converter.

  17. An Advanced Turbo-Brayton Converter for Radioisotope Power Systems

    NASA Astrophysics Data System (ADS)

    Zagarola, Mark V.; Izenson, Michael G.; Breedlove, Jeffrey J.; O'Connor, George M.; Ketchum, Andrew C.; Jetley, Richard L.; Simons, James K.

    2005-02-01

    Past work has shown that Brayton power converters are an attractive option for high power, long-duration space missions. More recently, Creare has shown that Brayton technology could be scaled with high efficiency and specific power to lower power levels suitable for radioisotope power conversion systems. Creare is currently leading the development of an advanced turbo-Brayton converter under NASA's Prometheus Program. The converter design is based on space-proven cryocooler technologies that have been shown to be safe; to provide long, maintenance-free lifetimes; and to have high reliability, negligible vibration emittance, and low EMI/EMC. The predicted performance of a converter at the beginning of life is greater than 20% (including electronic inefficiencies and overhead) with a converter specific power of greater than 8 We/kg for a test unit and greater than 15 We/kg for a flight unit. The degradation in performance over a 14-year mission lifetime is predicted to be negligible, and the primary life limiting factor is not expected to be an issue for greater than twice the mission duration. Work during the last year focused on the material and fabrication issues associated with a high temperature turbine and a lightweight recuperator, and the performance issues associated with the high-temperature insulation and power conversion electronics. The development of the converter is on schedule. Thermal vacuum testing to demonstrate a technology readiness level of 5 is currently planned for 2006.

  18. Investigations on a hybrid positron source with a granular converter

    NASA Astrophysics Data System (ADS)

    Artru, X.; Chaikovska, I.; Chehab, R.; Chevallier, M.; Dadoun, O.; Furukawa, K.; Guler, H.; Kamitani, T.; Miyahara, F.; Satoh, M.; Sievers, P.; Suwada, T.; Umemori, K.; Variola, A.

    2015-07-01

    Promising results obtained with crystal targets for positron production led to the elaboration of a hybrid source made of an axially oriented tungsten crystal, as a radiator, and an amorphous tungsten converter. If the converter is granular, made of small spheres, the heat dissipation is greatly enhanced and the thermal shocks reduced, allowing the consideration of such device for the future linear colliders. A positron source of this kind is investigated. Previous simulations have shown very promising results for the yield as for the energy deposition and the PEDD (Peak Energy Deposition Density). Here, we present detailed simulations made in this granular converter with emphasis on the energy deposition density, which is a critical parameter as learned from the breakdown of the SLC target. A test on the KEKB linac is foreseen; it will allow a determination of the energy deposited and the PEDD in the converter through temperature measurements. Four granular converters, made of W spheres of mm radius have been built at LAL-Orsay; they will be installed at KEK and compared to compact converters. A description of the experimental layout at KEK is provided. Applications to future linear colliders as CLIC and ILC are considered.

  19. Matrix Treatment of Ray Optics.

    ERIC Educational Resources Information Center

    Quon, W. Steve

    1996-01-01

    Describes a method to combine two learning experiences--optical physics and matrix mathematics--in a straightforward laboratory experiment that allows engineering/physics students to integrate a variety of learning insights and technical skills, including using lasers, studying refraction through thin lenses, applying concepts of matrix…

  20. The Lucas p-matrix

    NASA Astrophysics Data System (ADS)

    Kuhapatanakul, Kantaphon

    2015-11-01

    In this note, we study the Fibonacci and Lucas p-numbers. We introduce the Lucas p-matrix and companion matrices for the sums of the Fibonacci and Lucas p-numbers to derive some interesting identities of the Fibonacci and Lucas p-numbers.

  1. Student Transfer Matrix, Fall 1996.

    ERIC Educational Resources Information Center

    Oklahoma State Regents for Higher Education, Oklahoma City.

    The Student Transfer Matrix provides data on the numbers of students transferring from Oklahoma public and private institutions of higher education to other Oklahoma institutions, using data from receiving institutions. Among the highlights are: the number of students who transferred to four-year and two-year institutions remained steady at 57.8…

  2. Integrability and generalized monodromy matrix

    SciTech Connect

    Lhallabi, T.; Moujib, A.

    2007-09-15

    We construct the generalized monodromy matrix M-circumflex({omega}) of two-dimensional string effective action by introducing the T-duality group properties. The integrability conditions with general solutions depending on spectral parameter are given. This construction is investigated for the exactly solvable Wess, Zumino, Novikov, and Witten model in pp-wave limit when B=0.

  3. [Matrix metalloproteinases 2 and 9, their endogenous regulators, and angiotensin-converting enzyme in cervical squamous cell carcinoma].

    PubMed

    Timoshenko, O S; Kugaevskaya, E V; Gureeva, T A; Zavalishina, L E; Andreeva, Yu Yu; Solov'eva, N I

    2015-01-01

    Цель исследования — изучение особенностей экспрессии матриксных металлопротеиназ-2 и -9 (ММП-2, ММП-9), их тканевого ингибитора ТИМП-2, активатора плазминогена урокиназного типа (уАП), а также ангиотензинпревращающего фермента (АПФ) при плоскоклеточной карциноме шейки матки (ПКШМ). Материал и методы. Исследование проведено на образцах опухолевой ткани и морфологически нормальной ткани, прилегающей к опухоли. Использованы энзиматические методы с применением специфических субстратов, методы зимографии и иммуногистохимии. Результаты. Установлено, что существенное влияние на инвазивный потенциал ПКШМ оказывает увеличение экспрессии ММП-9 и уАП, а также снижение экспрессии ТИМП-2, в меньшей степени — изменение экспрессии ММП-2. ММП-9 может служить маркером инвазивного роста. Повышенная активность АПФ в раке подтверждает участие этого фермента в опухолевой прогрессии. В прилегающей к опухоли морфологически нормальной ткани обнаружена существенная экспрессия ММП-2 и ММП-9, и в ряде случаев — повышенная активность уАП и АПФ, что вносит дополнительный вклад в увеличение инвазивного потенциала опухоли. Заключение. Полученные данные важны для понимания механизмов прогрессии рака, имеют прогностическое значение и могут влиять на терапевтическую стратегию в отношении пациента.

  4. Early Oscillation Detection Technique for Hybrid DC/DC Converters

    NASA Technical Reports Server (NTRS)

    Wang, Bright L.

    2011-01-01

    Oscillation or instability is a situation that must be avoided for reliable hybrid DC/DC converters. A real-time electronics measurement technique was developed to detect catastrophic oscillations at early stages for hybrid DC/DC converters. It is capable of identifying low-level oscillation and determining the degree of the oscillation at a unique frequency for every individual model of the converters without disturbing their normal operations. This technique is specially developed for space-used hybrid DC/DC converters, but it is also suitable for most of commercial and military switching-mode power supplies. This is a weak-electronic-signal detection technique to detect hybrid DC/DC converter oscillation presented as a specific noise signal at power input pins. It is based on principles of feedback control loop oscillation and RF signal modulations, and is realized by using signal power spectral analysis. On the power spectrum, a channel power amplitude at characteristic frequency (CPcf) and a channel power amplitude at switching frequency (CPsw) are chosen as oscillation level indicators. If the converter is stable, the CPcf is a very small pulse and the CPsw is a larger, clear, single pulse. At early stage of oscillation, the CPcf increases to a certain level and the CPsw shows a small pair of sideband pulses around it. If the converter oscillates, the CPcf reaches to a higher level and the CPsw shows more high-level sideband pulses. A comprehensive stability index (CSI) is adopted as a quantitative measure to accurately assign a degree of stability to a specific DC/DC converter. The CSI is a ratio of normal and abnormal power spectral density, and can be calculated using specified and measured CPcf and CPsw data. The novel and unique feature of this technique is the use of power channel amplitudes at characteristic frequency and switching frequency to evaluate stability and identify oscillations at an early stage without interfering with a DC/DC converter s

  5. White Matter Signal Abnormality Quality Differentiates MCI that Converts to Alzheimer's Disease from Non-converters

    PubMed Central

    Lindemer, Emily R.; Salat, David H.; Smith, Eric E.; Nguyen, Khoa; Fischl, Bruce; Greve, Douglas N.

    2015-01-01

    The objective of this study was to assess how longitudinal change in the quantity and quality of white matter signal abnormalities (WMSAs) contributes to the progression from mild cognitive impairment (MCI) to Alzheimer's disease (AD). The Mahalanobis distance of WMSA from normal-appearing white matter using T1-, T2-, and PD-weighted MRI was defined as a quality measure for WMSA. Cross-sectional analysis of WMSA volume in 104 cognitively healthy older adults, 116 individuals with mild cognitive impairment who converted to AD within 3 years (MCI-C), 115 individuals with MCI that did not convert in that time (MCI-NC), and 124 individuals with AD from the Alzheimer's Disease Neuroimaging Initiative (ADNI) revealed that WMSA volume was substantially greater in AD relative to the other groups, but did not differ between MCI-NC and MCI-C. Longitudinally, MCI-C exhibited faster WMSA quality progression but not volume compared to matched MCI-NC beginning eighteen months prior to MCI-C conversion to AD. The strongest difference in rate of change was seen in the time period starting 6 months before MCI-C conversion to AD and ending 6 months after conversion (p < 0.001). The relatively strong effect in this time period relative to AD conversion in the MCI-C was similar to the relative rate of change in hippocampal volume, a traditional imaging marker of AD pathology. These data demonstrate changes in white matter tissue properties that occur within WMSA in individuals with MCI that will subsequently obtain a clinical diagnosis of AD within 18 months. Individuals with AD have substantially greater WMSA volume than all MCI suggesting that there is a progressive accumulation of WMSA with progressive disease severity, and that quality change predates changes in this total volume. Given the timing of the changes in WMSA tissue quality relative to the clinical diagnosis of AD, these findings suggest that WMSAs are a critical component for this conversion and are a critical

  6. Matrix metalloproteinases in fish biology and matrix turnover.

    PubMed

    Pedersen, Mona E; Vuong, Tram T; Rønning, Sissel B; Kolset, Svein O

    2015-01-01

    Matrix metalloproteinases have important functions for tissue turnover in fish, with relevance both for the fish industry and molecular and cellular research on embryology, inflammation and tissue repair. These metalloproteinases have been studied in different fish types, subjected to both aquaculture and experimental conditions. This review highlights studies on these metalloproteinases in relation to both fish quality and health and further, the future importance of fish for basic research studies.

  7. Multichannel analog-to-digital converters based on current mirrors for the optical systems

    NASA Astrophysics Data System (ADS)

    Krasilenko, Vladimir G.; Nikolskyy, A. I.; Nikolska, M. A.; Lobodzinska, R. F.

    2011-12-01

    The paper considers results of designing and modeling analogue-digital converters (ADC) based on current mirrors for the optical systems and neural networks with parallel inputs-outputs. Such ADC, named us multichannel analog-todigital converters based on current mirrors (M ADC CM). Compared with usual converters, for example, reading, a bitby- bit equilibration, and so forth, have a number of advantages: high speed and reliability, simplicity, small power consumption, the big degree of integration in linear and matrix structures. The considered aspects of designing of M_ADC CM in binary codes. Base digit cells (ABC) of such M_ADC CM, series-pipelined are connected in structures, consist from 20-30 CMOS the transistors, one photodiode, have low (1,5-3,5) supply voltage, work in current modes with the maximum values of currents (10-40)μA. Therefore such new principles of realization high-speed low-discharge M_ADC CM have allowed, as have shown modeling experiments, to reach time of transformation less than 20-30 nS at 5-6 bits of a binary code and the general power 1-5 mW. The quantity easily cascadable ABC depends on wordlength ADC, and makes n, and provides quantity of levels of quantization equal N=2n. Such simple enough on structure M ADC CM, having low power consumption <= 3 ÷ 5mW, supply voltage (3-7)V, is provided at the same time with good dynamic characteristics (frequency of digitization even for 1,5μm or 0,35 μm- CMOS-technologies has made 40 MHz, and can be increased 10 times) and accuracy (Δquantization 156,25nA for I max10μA) characteristics is show. The range can be transformed optical signals, taking into account sensitivity of modern photodetectors makes 20-200 μW in such ADC. M_ADC CM open new prospects for realization linear and matrix (with picture operands) micro photoelectronic structures which are necessary for neural networks, digital optoelectronic processors, neurofuzzy controllers, and so forth.

  8. High Density Power Converters for Photovoltaic Power Management

    NASA Astrophysics Data System (ADS)

    Sangwan, Rahul

    In typical photovoltaic systems, PV cells are connected in series to achieve high output voltages, which decreases conduction losses and helps the downstream power electronics operate at higher efficiencies. A series connection means that the current through the string is limited by the worst case cell, substring, or module, which can result in suboptimal operation of the rest of the string. Given how even small shading can have a large effect on performance, there has been growing interest in the use of distributed power management architectures to mitigate losses from variation in PV systems. In particular, partial power processing converters have gained traction as a means to improve the performance of PV arrays with small, distributed converters that configure in parallel with PV cells. These converters can use low voltage components, only process a fraction of the total power allowing them to achieve higher efficiencies and power density and also have higher reliability. This work details the design and operation of a partial power processing converter implemented as a Resonant Switched Capacitor (ReSC) converter. An integrated circuit (IC) is designed in 0.18 mum CMOS process. Operation at high frequencies (20-50 MHz) allows high levels of integration with air core inductors directly attached to the die through a gold bump, solder reflow process. Test results for the IC are presented with power density and efficiency metrics. The IC is then used as a partial power processing converter to implement equalization with a specially constructed PV panel. The converter is shown to mitigate power loss due to mismatch.

  9. Mechanotransduction: all signals point to cytoskeleton, matrix, and integrins

    NASA Technical Reports Server (NTRS)

    Alenghat, Francis J.; Ingber, Donald E.

    2002-01-01

    Mechanical stresses modulate cell function by either activating or tuning signal transduction pathways. Mechanotransduction, the process by which cells convert mechanical stimuli into a chemical response, occurs both in cells specialized for sensing mechanical cues and in parenchymal cells whose primary function is not mechanosensory. However, common among the various responses to mechanical stress is the importance of direct or indirect connections between the internal cytoskeleton, the extracellular matrix (ECM), and traditional signal transducing molecules. In many instances, these elements converge at focal adhesions, sites of structural attachment between the cytoskeleton and ECM that are anchored by cell surface integrin receptors. Alenghat and Ingber discuss the accumulating evidence for the central role of cytoskeleton, ECM, and integrin-anchored focal adhesions in several mechanotransduction pathways.

  10. Parallel algorithms for matrix computations

    SciTech Connect

    Plemmons, R.J.

    1990-01-01

    The present conference on parallel algorithms for matrix computations encompasses both shared-memory systems and distributed-memory systems, as well as combinations of the two, to provide an overall perspective on parallel algorithms for both dense and sparse matrix computations in solving systems of linear equations, dense or structured problems related to least-squares computations, eigenvalue computations, singular-value computations, and rapid elliptic solvers. Specific issues addressed include the influence of parallel and vector architectures on algorithm design, computations for distributed-memory architectures such as hypercubes, solutions for sparse symmetric positive definite linear systems, symbolic and numeric factorizations, and triangular solutions. Also addressed are reference sources for parallel and vector numerical algorithms, sources for machine architectures, and sources for programming languages.

  11. Sapphire reinforced alumina matrix composites

    NASA Technical Reports Server (NTRS)

    Jaskowiak, Martha H.; Setlock, John A.

    1994-01-01

    Unidirectionally reinforced A1203 matrix composites have been fabricated by hot pressing. Approximately 30 volume % of either coated or uncoated sapphire fiber was used as reinforcement. Unstabilized ZrO2 was applied as the fiber coating. Composite mechanical behavior was analyzed both after fabrication and after additional heat treatment. The results of composite tensile tests were correlated with fiber-matrix interfacial shear strengths determined from fiber push-out tests. Substantially higher strength and greater fiber pull-out were observed for the coated fiber composites for all processing conditions studied. The coated fiber composites retained up to 95% and 87% of their as-fabricated strength when heat treated at 14000C for 8 or 24 hours, respectively. Electron microscopy analysis of the fracture surfaces revealed extensive fiber pull-out both before and after heat treatment.

  12. High temperature polymer matrix composites

    NASA Technical Reports Server (NTRS)

    Meador, Michael A.

    1987-01-01

    With the increased emphasis on high performance aircraft the need for lightweight, thermal/oxidatively stable materials is growing. Because of their ease of fabrication, high specific strength, and ability to be tailored chemically to produce a variety of mechanical and physical properties, polymers and polymer matrix composites present themselves as attractive materials for a number of aeropropulsion applications. In the early 1970s researchers at the NASA Lewis Research Center developed a highly processable, thermally stable (600 F) polyimide, PMR-15. Since that time, PMR-15 has become commercially available and has found use in military aircraft, in particular, the F-404 engine for the Navy's F/A-18 strike fighter. The NASA Lewis'contributions to high temperature polymer matrix composite research will be discussed as well as current and future directions.

  13. Corrosion of Titanium Matrix Composites

    SciTech Connect

    Covino, B.S., Jr.; Alman, D.E.

    2002-09-22

    The corrosion behavior of unalloyed Ti and titanium matrix composites containing up to 20 vol% of TiC or TiB{sub 2} was determined in deaerated 2 wt% HCl at 50, 70, and 90 degrees C. Corrosion rates were calculated from corrosion currents determined by extrapolation of the tafel slopes. All curves exhibited active-passive behavior but no transpassive region. Corrosion rates for Ti + TiC composites were similar to those for unalloyed Ti except at 90 degrees C where the composites were slightly higher. Corrosion rates for Ti + TiB{sub 2} composites were generally higher than those for unalloyed Ti and increased with higher concentrations of TiB{sub 2}. XRD and SEM-EDS analyses showed that the TiC reinforcement did not react with the Ti matrix during fabrication while the TiB{sub 2} reacted to form a TiB phase.

  14. A Solid Core Heatpipe Reactor with Cylindrical Thermoelectric Converter Modules

    SciTech Connect

    Sayre, Edwin D.; Vaidyanathan, Sam

    2006-01-20

    A nuclear space power system that consists of a solid metal nuclear reactor core with heat pipes carrying energy to a cylindrical thermoelectric converter surrounding each of the heat pipes with a heat pipe radiator surrounding the thermoelectric converter is the most simple and reliable space power system. This means no single point of failure since each heat pipe and cylindrical converter is a separate power system and if one fails it will not affect the others. The heat pipe array in the solid core is designed so that if an isolated heat pipe or even two adjacent heat pipes fail, the remaining heat pipes will still transport the core heat without undue overheating of the uranium nitride fuel. The primary emphasis in this paper is on simplicity, reliability and fabricability of such a space nuclear power source. The core and heat pipes are made of Niobium 1% Zirconium alloy (Nb1Zr), with rhenium lined fuel tubes, bonded together by hot isostatic pressure (HIPing) and with sodium as the heat pipe working fluid, can be operated up to 1250K. The cylindrical thermoelectric converter is made by depositing the constituents of the converter around a Nb1%Zr tube and encasing it in a Nb 1% Zr alloy tube and HIPing the structure to get final bonding and to produce residual compressive stresses in all brittle materials in the converter. A radiator heat pipe filled with potassium that operates at 850K is bonded to the outside of the cylindrical converter for cooling. The solid core heat pipe and cylindrical converter are mated by welding during the final assembly. A solid core reactor with 150 heat pipes with a 0.650-inch (1.65 cm) ID and a 30-inch (76.2 cm) length with an output of 8 Watts per square inch as demonstrated by the SP100 PD2 cell tests will produce about 80 KW of electrical power. An advanced solid core reactor made with molybdenum 47% rhenium alloy, with lithium heat pipes and the PD2 theoretical output of 11 watts per square inch or advanced higher

  15. A Solid Core Heatpipe Reactor with Cylindrical Thermoelectric Converter Modules

    NASA Astrophysics Data System (ADS)

    Sayre, Edwin D.; Vaidyanathan, Sam

    2006-01-01

    A nuclear space power system that consists of a solid metal nuclear reactor core with heat pipes carrying energy to a cylindrical thermoelectric converter surrounding each of the heat pipes with a heat pipe radiator surrounding the thermoelectric converter is the most simple and reliable space power system. This means no single point of failure since each heat pipe and cylindrical converter is a separate power system and if one fails it will not affect the others. The heat pipe array in the solid core is designed so that if an isolated heat pipe or even two adjacent heat pipes fail, the remaining heat pipes will still transport the core heat without undue overheating of the uranium nitride fuel. The primary emphasis in this paper is on simplicity, reliability and fabricability of such a space nuclear power source. The core and heat pipes are made of Niobium 1% Zirconium alloy (Nb1Zr), with rhenium lined fuel tubes, bonded together by hot isostatic pressure, (HIPing) and with sodium as the heat pipe working fluid, can be operated up to 1250K. The cylindrical thermoelectric converter is made by depositing the constituents of the converter around a Nb1%Zr tube and encasing it in a Nb 1% Zr alloy tube and HIPing the structure to get final bonding and to produce residual compressive stresses in all brittle materials in the converter. A radiator heat pipe filled with potassium that operates at 850K is bonded to the outside of the cylindrical converter for cooling. The solid core heat pipe and cylindrical converter are mated by welding during the final assembly. A solid core reactor with 150 heat pipes with a 0.650-inch (1.65 cm) ID and a 30-inch (76.2 cm) length with an output of 8 Watts per square inch as demonstrated by the SP100 PD2 cell tests will produce about 80 KW of electrical power. An advanced solid core reactor made with molybdenum 47% rhenium alloy, with lithium heat pipes and the PD2 theoretical output of 11 watts per square inch or advanced higher

  16. SnapShot: Mechanosensing Matrix.

    PubMed

    Irianto, Jerome; Pfeifer, Charlotte R; Xia, Yuntao; Discher, Dennis E

    2016-06-16

    Cells sense and respond to properties of their microenvironment that can affect cell morphology, protein levels and localization, gene expression, and even nuclear integrity. Tissue micro-stiffness, largely influenced by extracellular matrix, varies dramatically within an organism and can be a useful parameter to both clarify and organize a wide range of cell and molecular processes, such as genomic changes in cancer. PMID:27315485

  17. New zero voltage switching DC converter with flying capacitors

    NASA Astrophysics Data System (ADS)

    Lin, Bor-Ren; Shiau, Tung-Yuan

    2016-04-01

    A new soft switching converter is presented for medium power applications. Two full-bridge converters are connected in series at high voltage side in order to limit the voltage stress of power switches at Vin/2. Therefore, power metal-oxide-semiconductor field-effect transistors (MOSFETs) with 600 V voltage rating can be adopted for 1200 V input voltage applications. In order to balance two input split capacitor voltages in every switching cycle, two flying capacitors are connected on the AC side of two full-bridge converters. Phase-shift pulse-width modulation (PS-PWM) is adopted to regulate the output voltage. Based on the resonant behaviour by the output capacitance of MOSFETs and the resonant inductance, active MOSFETs can be turned on under zero voltage switching (ZVS) during the transition interval. Thus, the switching losses of power MOSFETs are reduced. Two full-bridge converters are used in the proposed circuit to share load current and reduce the current stress of passive and active components. The circuit analysis and design example of the prototype circuit are provided in detail and the performance of the proposed converter is verified by the experiments.

  18. Multipurpose Power Converter for Non-Grid-Connected Microsystems

    NASA Astrophysics Data System (ADS)

    Vovos, Panagis N.; Georgakas, Konstantinos G.

    2015-04-01

    The aim of this paper is to present a multipurpose converter, appropriate for non-grid-connected microsystems, which are prone to harmonic distortion. The converter suppresses harmonics by injecting mirror harmonics in the modulation stage. An important property is that it continuously monitors and significantly reduces the harmonic content without the use of active or passive low-frequency filters. This is under constant switching frequency, no matter if the harmonics are mainly created by the source, the loads or even its own operation. The converter is regulating output voltage using typical fuzzy control. The two types of control (harmonic and voltage) do not seem to affect each other during operation. Furthermore, it can supply either dc or ac loads from a dc source. The versatility of the converter is a useful property for remote or mobile micropower systems, where neither sources nor loads are of a single type. The converter has been tested successfully for a combination of harmonic-injecting electric appliances and various load step changes.

  19. Sub-picosecond Resolution Time-to-Digital Converter

    SciTech Connect

    Ph D, Vladimir Bratov; Ph D, Vladimir Katzman; MS EE, Jeb Binkley

    2006-03-30

    Time-to-digital converters with sub-picosecond resolutions are needed to satisfy the requirements of time-on-flight measurements of the next generation of high energy and nuclear physics experiments. The converters must be highly integrated, power effective, low cost, and feature plug-and-play capabilities to handle the increasing number of channels (up to hundreds of millions) in future Department of Energy experiments. Current state-off-the-art time-to-digital converter integrated circuits do not have the sufficient degree of integration and flexibility to fulfill all the described requirements. During Phase I, the Advanced Science and Novel Technology Company in cooperation with the nuclear physics division of the Oak Ridge National Laboratory has developed the architecture of a novel time-to-digital converter with multiple channels connected to an external processor through a special interfacing block and synchronized by clock signals generated by an internal phase-locked loop. The critical blocks of the system including signal delay lines and delay-locked loops with proprietary differential delay cells, as well as the required digital code converter and the clock period counter have been designed and simulated using the advanced SiGe120 BiCMOS technological process. The results of investigations demonstrate a possibility to achieve the digitization accuracy within 1ps. ADSANTEC has demonstrated the feasibility of the proposed concept in computer simulations. The proposed system will be a critical component for the next generation of NEP experiments.

  20. Easily processable multimodal spectral converters based on metal oxide/organic—inorganic hybrid nanocomposites

    NASA Astrophysics Data System (ADS)

    Julián-López, Beatriz; Gonell, Francisco; Lima, Patricia P.; Freitas, Vânia T.; André, Paulo S.; Carlos, Luis D.; Ferreira, Rute A. S.

    2015-10-01

    This manuscript reports the synthesis and characterization of the first organic-inorganic hybrid material exhibiting efficient multimodal spectral converting properties. The nanocomposite, made of Er3+, Yb3+ codoped zirconia nanoparticles (NPs) entrapped in a di-ureasil d-U(600) hybrid matrix, is prepared by an easy two-step sol-gel synthesis leading to homogeneous and transparent materials that can be very easily processed as monolith or film. Extensive structural characterization reveals that zirconia nanocrystals of 10-20 nm in size are efficiently dispersed into the hybrid matrix and that the local structure of the di-ureasil is not affected by the presence of the NPs. A significant enhancement in the refractive index of the di-ureasil matrix with the incorporation of the ZrO2 nanocrystals is observed. The optical study demonstrates that luminescent properties of both constituents are perfectly preserved in the final hybrid. Thus, the material displays a white-light photoluminescence from the di-ureasil component upon excitation at UV/visible radiation and also intense green and red emissions from the Er3+- and Yb3+-doped NPs after NIR excitation. The dynamics of the optical processes were also studied as a function of the lanthanide content and the thickness of the films. Our results indicate that these luminescent hybrids represent a low-cost, environmentally friendly, size-controlled, easily processed and chemically stable alternative material to be used in light harvesting devices such as luminescent solar concentrators, optical fibres and sensors. Furthermore, this synthetic approach can be extended to a wide variety of luminescent NPs entrapped in hybrid matrices, thus leading to multifunctional and versatile materials for efficient tuneable nonlinear optical nanodevices.

  1. Production and characterization of para-hydrogen gas for matrix isolation infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Sundararajan, K.; Sankaran, K.; Ramanathan, N.; Gopi, R.

    2016-08-01

    Normal hydrogen (n-H2) has 3:1 ortho/para ratio and the production of enriched para-hydrogen (p-H2) from normal hydrogen is useful for many applications including matrix isolation experiments. In this paper, we describe the design, development and fabrication of the ortho-para converter that is capable of producing enriched p-H2. The p-H2 thus produced was probed using infrared and Raman techniques. Using infrared measurement, the thickness and the purity of the p-H2 matrix were determined. The purity of p-H2 was determined to be >99%. Matrix isolation infrared spectra of trimethylphosphate (TMP) and acetylene (C2H2) were studied in p-H2 and n-H2 matrices and the results were compared with the conventional inert matrices.

  2. Comparison of optics and electronics for the calculation of matrix-vector products

    NASA Technical Reports Server (NTRS)

    Gary, C. K.

    1992-01-01

    Optical processors are attractive because of their ability to perform massively parallel operations such as matrix vector products. The inherently analog nature of optical calculations requires that optical processors be based on analog computations. While the speed at which such analog operations can be performed as well as the natural parallelism of optical systems are great advantages of optical processors, the analog representation of values severely limits the achievable accuracy. Furthermore, optical processors are limited by the need to convert information to and from the intensity of light. Digitization can be used to increase the accuracy of optical matrix-vector processors, but causes a severe reduction in speed. This paper compares the throughput and power requirements of optical and electronic processors, showing that optical matrix-vector processors can provide a greater number of operations/Watt than conventional electronics.

  3. Integrable matrix theory: Level statistics

    NASA Astrophysics Data System (ADS)

    Scaramazza, Jasen A.; Shastry, B. Sriram; Yuzbashyan, Emil A.

    2016-09-01

    We study level statistics in ensembles of integrable N ×N matrices linear in a real parameter x . The matrix H (x ) is considered integrable if it has a prescribed number n >1 of linearly independent commuting partners Hi(x ) (integrals of motion) "]Hi(x ) ,Hj(x ) ]">H (x ) ,Hi(x ) =0 , for all x . In a recent work [Phys. Rev. E 93, 052114 (2016), 10.1103/PhysRevE.93.052114], we developed a basis-independent construction of H (x ) for any n from which we derived the probability density function, thereby determining how to choose a typical integrable matrix from the ensemble. Here, we find that typical integrable matrices have Poisson statistics in the N →∞ limit provided n scales at least as logN ; otherwise, they exhibit level repulsion. Exceptions to the Poisson case occur at isolated coupling values x =x0 or when correlations are introduced between typically independent matrix parameters. However, level statistics cross over to Poisson at O (N-0.5) deviations from these exceptions, indicating that non-Poissonian statistics characterize only subsets of measure zero in the parameter space. Furthermore, we present strong numerical evidence that ensembles of integrable matrices are stationary and ergodic with respect to nearest-neighbor level statistics.

  4. Integrin Dynamics and Matrix Assembly

    PubMed Central

    Pankov, Roumen; Cukierman, Edna; Katz, Ben-Zion; Matsumoto, Kazue; Lin, Diane C.; Lin, Shin; Hahn, Cornelia; Yamada, Kenneth M.

    2000-01-01

    Fibronectin matrix assembly is a multistep, integrin-dependent process. To investigate the role of integrin dynamics in fibronectin fibrillogenesis, we developed an antibody-chasing technique for simultaneous tracking of two integrin populations by different antibodies. We established that whereas the vitronectin receptor αvβ3 remains within focal contacts, the fibronectin receptor α5β1 translocates from focal contacts into and along extracellular matrix (ECM) contacts. This escalator-like translocation occurs relative to the focal contacts at 6.5 ± 0.7 μm/h and is independent of cell migration. It is induced by ligation of α5β1 integrins and depends on interactions with a functional actin cytoskeleton and vitronectin receptor ligation. During cell spreading, translocation of ligand-occupied α5β1 integrins away from focal contacts and along bundles of actin filaments generates ECM contacts. Tensin is a primary cytoskeletal component of these ECM contacts, and a novel dominant-negative inhibitor of tensin blocked ECM contact formation, integrin translocation, and fibronectin fibrillogenesis without affecting focal contacts. We propose that translocating α5β1 integrins induce initial fibronectin fibrillogenesis by transmitting cytoskeleton-generated tension to extracellular fibronectin molecules. Blocking this integrin translocation by a variety of treatments prevents the formation of ECM contacts and fibronectin fibrillogenesis. These studies identify a localized, directional, integrin translocation mechanism for matrix assembly. PMID:10704455

  5. MALDI Matrix Research for Biopolymers

    PubMed Central

    Fukuyama, Yuko

    2015-01-01

    Matrices are necessary materials for ionizing analytes in matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS). The choice of a matrix appropriate for each analyte controls the analyses. Thus, in some cases, development or improvement of matrices can become a tool for solving problems. This paper reviews MALDI matrix research that the author has conducted in the recent decade. It describes glycopeptide, carbohydrate, or phosphopeptide analyses using 2,5-dihydroxybenzoic acid (2,5-DHB), 1,1,3,3-tetramethylguanidinium (TMG) salts of p-coumaric acid (CA) (G3CA), 3-aminoquinoline (3-AQ)/α-cyano-4-hydroxycinnamic acid (CHCA) (3-AQ/CHCA) or 3-AQ/CA and gengeral peptide, peptide containing disulfide bonds or hydrophobic peptide analyses using butylamine salt of CHCA (CHCAB), 1,5-diaminonaphthalene (1,5-DAN), octyl 2,5-dihydroxybenzoate (alkylated dihydroxybenzoate, ADHB), or 1-(2,4,6-trihydroxyphenyl)octan-1-one (alkylated trihydroxyacetophenone, ATHAP). PMID:26819908

  6. Quartz crystal microbalance based on passive frequency to voltage converter

    SciTech Connect

    Burda, Ioan; Tunyagi, Arthur

    2012-02-15

    In dynamics of evaporation or drying of microdrops from a solid surface, a faster and precise quartz crystal microbalance (QCM) is needed. The fast QCM based on frequency to voltage converter is an attractive and powerful tool in the investigation of the dynamic regime of evaporation to translate the frequency shift in terms of a continuous voltage change. The frequency shift monitoring in fast QCM applications is a real challenge for electronic processing interface. Originally developed as a frequency shift processing interface, this novel passive frequency to voltage converter can produce faster, stable, and accurate results in regard to the QCM sensor behavior. In this article, the concept and circuit of passive frequency to voltage converter will be explained followed by static and dynamic characterization. Experimental results of microdrops evaporation will be given.

  7. Controllable all-fiber orbital angular momentum mode converter.

    PubMed

    Li, Shuhui; Mo, Qi; Hu, Xiao; Du, Cheng; Wang, Jian

    2015-09-15

    We present a scheme to realize a controllable, scalable, low-cost, and versatile all-fiber orbital angular momentum (OAM) converter. The converter consists of a two-mode fiber (TMF) with its input terminal welded with a single-mode fiber, a mechanical long-period grating (LPG), a mechanical rotator, metal flat slabs, and a fiber polarization controller. The LPG is employed to convert the fundamental fiber mode to higher-order modes and the flat slabs are used to stress the TMF to adjust the relative phase difference between two orthogonal higher-order modes. Selective conversion from the LP(01) mode to the LP(11a), LP(11b), OAM(-1), or OAM(+1) mode is demonstrated in the experiment.

  8. A compact Raman converter for UV-VIS spectrometers.

    PubMed

    Bisson, Patrick J; Whitten, James E

    2015-05-01

    A small form factor, easily constructed converter that adapts fiber coupled UV/VIS CCD detector-based spectrometers into a right angle scattering Raman spectrometer is described. Its design philosophy and design are discussed. An example measurement, the depolarization ratio of carbon tetrachloride, a classic Raman test compound, is presented. The unique instrument features a blue-violet (405 nm wavelength) diode laser that takes advantage of the inverse fourth power wavelength dependence of Raman scattering. The converter also features Glan-Thompson polarizing prisms that enable measurement of depolarization ratios. The spectrometer is also capable of measuring a standard Raman spectrum. A fiber optic link offers flexibility when adapting the converter to any spectrometer system that accepts a fiber optic input. The performance of the instrument is critically discussed in the context of an example measurement.

  9. Free-piston Stirling component test power converter

    NASA Technical Reports Server (NTRS)

    Dochat, George; Dhar, Manmohan

    1991-01-01

    The National Aeronautics and Space Administration (NASA) has been evaluating free-piston Stirling power converters (FPSPCs) for use on a wide variety of space missions. They provide high reliability, long life, and efficient operation and can be coupled with all potential heat sources, various heat input and heat rejection systems, and various power management and distribution systems. FPSPCs can compete favorably with alternative power conversion systems over a range of hundreds of watts to megawatts. Mechanical Technology Incorporated (MTI) is developing FPSPC technology under contract to NASA Lewis Research Center and will demonstrate this technology in two full-scale power converters operating at space temperature conditions. The testing of the first of these, the component test power converter (CTPC), was initiated in Spring 1991 to evaluate mechanical operation at space operating temperatures. The CTPC design, hardware fabrication, and initial test results are reviewed.

  10. Methods for degrading or converting plant cell wall polysaccharides

    DOEpatents

    Berka, Randy; Cherry, Joel

    2008-08-19

    The present invention relates to methods for converting plant cell wall polysaccharides into one or more products, comprising: treating the plant cell wall polysaccharides with an effective amount of a spent whole fermentation broth of a recombinant microorganism, wherein the recombinant microorganism expresses one or more heterologous genes encoding enzymes which degrade or convert the plant cell wall polysaccharides into the one or more products. The present invention also relates to methods for producing an organic substance, comprising: (a) saccharifying plant cell wall polysaccharides with an effective amount of a spent whole fermentation broth of a recombinant microorganism, wherein the recombinant microorganism expresses one or more heterologous genes encoding enzymes which degrade or convert the plant cell wall polysaccharides into saccharified material; (b) fermenting the saccharified material of step (a) with one or more fermenting microoganisms; and (c) recovering the organic substance from the fermentation.

  11. Lithium and potassium heat pipes for thermionic converters

    NASA Technical Reports Server (NTRS)

    Miskolczy, G.; Kroeger, E. W.

    1978-01-01

    A prototypic heat pipe system for an out-of-core thermionic reactor was built and tested. The emitter of the concentric thermionic converter consists of the condenser of a tungsten heat pipe utilizing a lithium working fluid. The evaporator section of the emitter heat pipe is radiation heated to simulate the thermal input from the nuclear reactor. The emitter heat pipe thermal transport is matched to the thermionic converter input requirement. The collector heat pipe of niobium, 1% zirconium alloy uses potassium as the working fluid. The thermionic collector is coupled to the heat pipe by a tapered conical joint designed to minimize the temperature drop. The collector heat flux matches the design requirements of the thermionic converter.

  12. Lithium and potassium heat pipes for thermionic converters

    NASA Technical Reports Server (NTRS)

    Miskolczy, G.; Kroeger, E.

    1978-01-01

    A prototypic heat pipe system for an out-of-core thermionic reactor has been built and tested. The emitter of the concentric thermionic converter consists of the condenser of a tungsten heat pipe utilizing a lithium working fluid. The evaporator section of the emitter heat pipe is radiation heated to simulate the thermal input from the nuclear reactor. The emitter heat pipe thermal transport is matched to the thermionic converter input requirement. The collector heat pipe of niobium, 1%-zirconium alloy uses potassium as the working fluid. The thermionic collector is coupled to the heat pipe by a tapered conical joint designed to minimize the temperature drop. The area ratio of the evaporator to condenser is 16:1, which increases the radiation area. The composite wick structure consists of seven arteries and cylindrical wraps. The collector heat flux matches the design requirements of the thermionic converter.

  13. ASDTIC duty-cycle control for power converters

    NASA Technical Reports Server (NTRS)

    Lalli, V. R.; Schoenfeld, A. D.

    1972-01-01

    The application of analog signal to discrete interval converter (ASDTIC), a hybrid micromodule, two loop control subsystem, to a switching, stepdown dc to dc converter is described. The power circuitry, interface and ASDTIC subsystems used in this switching regulator were developed to exhibit the improved regulation, transient performance, regulator stability and freedom from the effects of variations in parts characteristics due to environmental changes and aging. ASDTIC can be used with other types of power circuits that use duty-cycle control techniques by simple changes in the interface subsystem. The circuitry and performance characteristics of a +10V dc switching converter as well as that of the ASDTIC micromodule are described. Realization of the ASDTIC hybrid micromodule has been accomplished with a hermetically sealed, beam-lead, bonded/deposited nichrome thin film resistors, discrete capacitors and integrated circuits on dilithic, glazed alumina substrates using 22 feed through terminals in an integrated package.

  14. Auxiliary quasi-resonant dc tank electrical power converter

    DOEpatents

    Peng, Fang Z.

    2006-10-24

    An auxiliary quasi-resonant dc tank (AQRDCT) power converter with fast current charging, voltage balancing (or charging), and voltage clamping circuits is provided for achieving soft-switched power conversion. The present invention is an improvement of the invention taught in U.S. Pat. No. 6,111,770, herein incorporated by reference. The present invention provides faster current charging to the resonant inductor, thus minimizing delay time of the pulse width modulation (PWM) due to the soft-switching process. The new AQRDCT converter includes three tank capacitors or power supplies to achieve the faster current charging and minimize the soft-switching time delay. The new AQRDCT converter further includes a voltage balancing circuit to charge and discharge the three tank capacitors so that additional isolated power supplies from the utility line are not needed. A voltage clamping circuit is also included for clamping voltage surge due to the reverse recovery of diodes.

  15. Performance results of the ICON FUV sealed tube converters

    NASA Astrophysics Data System (ADS)

    Darling, N. T.; Siegmund, O. H. W.; Curtis, T.; Jelinsky, S.; McPhate, J.; Tedesco, J.

    2015-09-01

    The ICON Far Ultra Violet Imaging Spectrograph (ICON FUV) instrument includes one sealed tube microchannel plate (MCP) converter for each of two (135.6 nm and 157 nm wavelength) channels. These are each integrated with a CCD camera assembly to provide ICON FUV's sensor systems. The ICON FUV sealed tube converters have a 27mm active area and include a double MCP stack with a cesium iodide (CsI) photocathode, a magnesium fluoride (MgF2) input window, a ceramic and Kovar brazed mechanical structure and a phosphor output screen. Performance characteristics are measured for each detector throughout manufacturing and before shipping and include the collection of gain-voltage data, pulse height distributions, flat field images of the output window, background count rates and images, quantum efficiency curves and resolution characteristics. The design and testing of the ICON FUV sealed tube converters are described here.

  16. Secure ultrafast communication with spatial-temporal converters.

    PubMed

    Matoba, O; Javidi, B

    2000-06-10

    An encrypted database interfaced with an ultrafast secure data communication system using spatial-temporal converters is proposed. The original spatial signal is optically encrypted, and the encrypted signal is holographically stored in a storage medium such as photorefractive materials. The spatially encrypted signal is sampled to avoid the overlap of each datum at the receiver. The sampled data are converted into a temporal signal to transmit the information through an optical fiber. At the receiver the temporal signal is converted back into the spatially encrypted signal. Retrieval of the original data can be achieved when the correct phase key is used in the decryption system. We developed an expression for encrypted output and decrypted data. We numerically evaluate the effect of sampling the spatially encrypted signal on the quality of the decrypted data.

  17. A high-efficiency thermoelectric converter for space applications

    SciTech Connect

    Metzger, J.D.; El-Genk, M.S.

    1990-12-31

    This paper presents a concept for using high-temperature superconducting materials in thermoelectric generators (SCTE) to produce electricity at conversion efficiencies approaching 50% of the Carrot efficiency. The SCTE generator is applicable to systems operating in temperature ranges of high-temperature superconducting materials and thus would be a low-grade converter. Operating in cryogenic temperature ranges provides the advantage of inherently increasing the limits of the Carrot efficiency. Potential applications are for systems operating in space where the ambient temperatures are in the cryogenic temperature range. The advantage of using high-temperature superconducting material in a thermoelectric converter is that it would significantly reduce or eliminate the Joule heating losses in a thermoelectric element. This paper investigates the system aspects and the material requirements of the SCTE converter concept, and presents a conceptual design and an application for a space power system.

  18. Power line carrier interference from HVDC converter terminals

    SciTech Connect

    Tatro, P.J.; Adamson, K.A. ); Eitzmann, M.A.; Smead, M. . Power Systems Engineering Dept.)

    1993-07-01

    Power line carrier (PLC) equipment typically operates in the frequency range from 25 kHz to 300 kHz. Interference studies for HVDC converters usually concentrate on interference from noise sources within this frequency range. However, operating experience at the Sandy Pond converter terminal has indicated that PLC equipment is also susceptible to interference from sources of power system harmonics below the PLC frequency range. Extensive field testing and analytical studies have shown that each PLC circuit has a resonant frequency below the operating frequency. If excited at this resonant frequency, high voltages may exist within the PLC circuit. The resulting saturation of PLC components leads to local generation of radio frequency (RF) noise that interferes with proper operation of PLC circuits. Sources of power system harmonics in the 3-10 kHz range, such as line commutated dc converters, are potential sources of this type of interference.

  19. Design of Compact Multi-Megawatt Mode Converter

    SciTech Connect

    Dolgashev, V.A.; Tantawi, S.G.; Nantista, C.D.; /SLAC

    2006-03-21

    Experience gained during recent operation of high power 11.424 GHz rf sources for accelerators led to new, more strict requirements on system components. One of the basic components of such a system is a mode converter that transforms the rectangular waveguide mode into the TE{sub 01} mode in circular waveguide. With such a converter, it is possible to minimize the use of WR90 rectangular waveguide which was shown to be a weak part of the previous system at power levels higher than 100 MW and pulse lengths on the order of a microsecond. We used several methods to design a mode converter with extremely low parasitic mode conversion and compact size. These methods employ HFSS[4] and include multi-parameter searches, concurrent optimization with a mode-matching code Cascade[2], cascading of resulting S-matrices, and tolerance analysis using perturbation techniques. This report describes the design methods and presents results.

  20. Controllable all-fiber orbital angular momentum mode converter.

    PubMed

    Li, Shuhui; Mo, Qi; Hu, Xiao; Du, Cheng; Wang, Jian

    2015-09-15

    We present a scheme to realize a controllable, scalable, low-cost, and versatile all-fiber orbital angular momentum (OAM) converter. The converter consists of a two-mode fiber (TMF) with its input terminal welded with a single-mode fiber, a mechanical long-period grating (LPG), a mechanical rotator, metal flat slabs, and a fiber polarization controller. The LPG is employed to convert the fundamental fiber mode to higher-order modes and the flat slabs are used to stress the TMF to adjust the relative phase difference between two orthogonal higher-order modes. Selective conversion from the LP(01) mode to the LP(11a), LP(11b), OAM(-1), or OAM(+1) mode is demonstrated in the experiment. PMID:26371940

  1. Choosing to Convert to Critical Access Hospital Status

    PubMed Central

    Dalton, Kathleen; Slifkin, Rebecca; Poley, Stephanie; Fruhbeis, Melissa

    2003-01-01

    The authors profile facilities converting to critical access hospitals (CAHs) from 1998-2000, comparing characteristics of their communities, operations, and finances to those of other small rural providers. Counties where CAHs are located are more sparsely populated, but do not have substantially different sociodemographic profiles than other rural counties. Converting hospitals' acute daily census averaged well below the statutory limit of 15, but over one-half reduced unused bed capacity to meet CAH size limitations. The average case-mix adjusted Medicare cost per case was 16-percent higher for CAH converters than for other small hospitals and their financial ratios were substantially worse, although many other operating characteristics were similar. PMID:14997697

  2. A compact Raman converter for UV-VIS spectrometers

    NASA Astrophysics Data System (ADS)

    Bisson, Patrick J.; Whitten, James E.

    2015-05-01

    A small form factor, easily constructed converter that adapts fiber coupled UV/VIS CCD detector-based spectrometers into a right angle scattering Raman spectrometer is described. Its design philosophy and design are discussed. An example measurement, the depolarization ratio of carbon tetrachloride, a classic Raman test compound, is presented. The unique instrument features a blue-violet (405 nm wavelength) diode laser that takes advantage of the inverse fourth power wavelength dependence of Raman scattering. The converter also features Glan-Thompson polarizing prisms that enable measurement of depolarization ratios. The spectrometer is also capable of measuring a standard Raman spectrum. A fiber optic link offers flexibility when adapting the converter to any spectrometer system that accepts a fiber optic input. The performance of the instrument is critically discussed in the context of an example measurement.

  3. Fast polar decomposition of an arbitrary matrix

    NASA Technical Reports Server (NTRS)

    Higham, Nicholas J.; Schreiber, Robert S.

    1988-01-01

    The polar decomposition of an m x n matrix A of full rank, where m is greater than or equal to n, can be computed using a quadratically convergent algorithm. The algorithm is based on a Newton iteration involving a matrix inverse. With the use of a preliminary complete orthogonal decomposition the algorithm can be extended to arbitrary A. How to use the algorithm to compute the positive semi-definite square root of a Hermitian positive semi-definite matrix is described. A hybrid algorithm which adaptively switches from the matrix inversion based iteration to a matrix multiplication based iteration due to Kovarik, and to Bjorck and Bowie is formulated. The decision when to switch is made using a condition estimator. This matrix multiplication rich algorithm is shown to be more efficient on machines for which matrix multiplication can be executed 1.5 times faster than matrix inversion.

  4. Inter-subject neural code converter for visual image representation.

    PubMed

    Yamada, Kentaro; Miyawaki, Yoichi; Kamitani, Yukiyasu

    2015-06-01

    Brain activity patterns differ from person to person, even for an identical stimulus. In functional brain mapping studies, it is important to align brain activity patterns between subjects for group statistical analyses. While anatomical templates are widely used for inter-subject alignment in functional magnetic resonance imaging (fMRI) studies, they are not sufficient to identify the mapping between voxel-level functional responses representing specific mental contents. Recent work has suggested that statistical learning methods could be used to transform individual brain activity patterns into a common space while preserving representational contents. Here, we propose a flexible method for functional alignment, "neural code converter," which converts one subject's brain activity pattern into another's representing the same content. The neural code converter was designed to learn statistical relationships between fMRI activity patterns of paired subjects obtained while they saw an identical series of stimuli. It predicts the signal intensity of individual voxels of one subject from a pattern of multiple voxels of the other subject. To test this method, we used fMRI activity patterns measured while subjects observed visual images consisting of random and structured patches. We show that fMRI activity patterns for visual images not used for training the converter could be predicted from those of another subject where brain activity was recorded for the same stimuli. This confirms that visual images can be accurately reconstructed from the predicted activity patterns alone. Furthermore, we show that a classifier trained only on predicted fMRI activity patterns could accurately classify measured fMRI activity patterns. These results demonstrate that the neural code converter can translate neural codes between subjects while preserving contents related to visual images. While this method is useful for functional alignment and decoding, it may also provide a basis for

  5. Reducing cold-start emissions by catalytic converter thermal management

    SciTech Connect

    Burch, S D; Potter, T F; Keyser, M A; Brady, M J; Michaels, K F

    1995-01-01

    Vacuum insulation and phase-change thermal storage have been used to enhance the heat retention of a prototype catalytic converter. Storing heat in the converter between trips allows exhaust gases to be converted more quickly, significantly reducing cold-start emissions. Using a small metal hydride, the thermal conductance of the vacuum insulation can be varied continuously between 0.49 and 27 W/m{sup 2}K (R-12 to R-0.2 insulation) to prevent overheating of the catalyst. A prototype was installed in a Dodge Neon with a 2.0-liter engine. Following a standard preconditioning and a 23-hour cold soak, an FTP (Federal Test Procedure) emissions test was performed. Although exhaust temperatures during the preconditioning were not hot enough to melt the phase-change material, the vacuum insulation performed well, resulting in a converter temperature of 146{degrees}C after the 23-hour cold soak at 27{degrees}C. Compared to the same converter at ambient conditions, overall emissions of CO and HC were reduced by 52 % and 29 %, to 0.27 and 0.037 g/mile, respectively. The maximum converter temperature during the FTP cycle was 720{degrees}C. This limited testing was performed with a nearly-fresh palladium-only catalyst, but demonstrates the potential of this vacuum insulation approach for emissions reduction and thermal control. Further testing is ongoing. An initial assessment of several production issues is made, including high-volume fabrication challenges, durability, and cost.

  6. Ozone and heavy metals from automobile catalytic converters.

    PubMed

    Ballach, H J

    1997-01-01

    The introduction of the 3-way catalytic converter is presently being acclaimed by different sources in Germany as the solution to the ozone problem. This hypothesis is viewed with scepticism: studies conducted in the USA, where the 3-way catalytic converter was introduced as early as 1975, show that the ozone problem has not been resolved by any means in that country. Moreover, the employment of the catalytic converter is associated with the emission of various elements occurring otherwise at extremely low background concentrations, e.g.the elements in the platinum group (Pt, Pd and Rh). A brief review of the literature reveals, for example, that platinum exhibited an unexpectedly high rate of accumulation in upper soil layers near highways in Germany within a few years of the introduction of catalytic converters. The focus of this paper is on impact research. My own studies have shown that water-soluble Pt 4. accumulates at a high rate in poplar roots. A six-week exposure of poplar cuttings to 34.8 ppb Pt 4+ results in disturbances affecting the water balance of the plants and, in conjunction with this, typical symptoms of moderate water stress. Cerium (Ce), another element released by catalytic converters, also displays a high degree of accumulation in plant roots. Water-soluble Pt4+ accumulates to an even greater degree in soil, giving rise to the following series arranged in order of decreasing affinity to platinum: soil > fine roots > coarse roots. In long-term experiments, even the metallic platinum contained in the active layer of catalytic converters accumulated in plant roots; the resulting distribution among soil, fine roots and coarse roots was comparable to that of water-soluble platinum. Possible uptake mechanisms are discussed. The first results of this study indicate that platinum apparently belongs to the elements with a strong affinity to humic matter, a fact which could possibly explain its especially heavy accumulation in upper soil layers.

  7. Power Management and Distribution System Developed for Thermionic Power Converters

    NASA Technical Reports Server (NTRS)

    Baez, Anastacio N.

    1998-01-01

    A spacecraft solar, bimodal system combines propulsion and power generation into a single integrated system. An Integrated Solar Upper Stage (ISUS) provides orbital transfer capabilities, power generation for payloads, and onboard propulsion to the spacecraft. A key benefit of a bimodal system is a greater payload-to-spacecraft mass ratio resulting in lower launch vehicle requirements. Scaling down to smaller launch vehicles increases space access by reducing overall mission cost. NASA has joined efforts with the Air Force Phillips Laboratory to develop enabling technologies for such a system. The NASA/Air Force bimodal concept uses solar concentrators to focus energy into an integrated power plant. This power plant consists of a graphite core that stores thermal energy within a cavity. An array of thermionic converters encircles the graphite cavity and provides electrical energy conversion functions. During the power generation phase of the bimodal system, the thermionic converters are exposed to the heated cavity and convert the thermal energy to electricity. Near-term efforts of the ISUS bimodal program are focused on a ground demonstration of key technologies in order to proceed to a full space flight test. Thermionic power generation is one key technology of the bimodal concept. Thermionic power converters impose unique operating requirements upon a power management and distribution (PMAD) system design. Single thermionic converters supply large currents at very low voltages. Operating voltages can vary over a range of up to 3 to 1 as a function of operating temperature. Most spacecraft loads require regulated 28-volts direct-current (Vdc) power. A combination of series-connected converters and powerprocessing boosters is required to deliver power to the spacecraft's payloads at this level.

  8. Exploration of the Chaotic Behaviour in a Buck-Boost Converter Depending on the Converter and Load Elements

    NASA Astrophysics Data System (ADS)

    Demirbaş, Şevki; Fidanboy, Hikmet; Kurt, Erol

    2016-08-01

    In this paper, detailed analyses of the chaotic behavior observed in a buck-boost converter are presented. Although this basic converter system is already known world-wide for the purpose of dc-dc conversion of the output of renewable energy systems, it indicates certain chaotic regimes where both the output amplitude and frequency change randomly. This chaotic regime can yield an unstable output over the resistive or resistive/inductive electrical loads. This study presents a detailed map for the regular and chaotic regions in terms of material parameters, such as converter capacitance C, resistive load R, and inductive load L. Thus, the stable area of operation for efficient and renewable electricity production will be ascertained for the studied converter system. We emphasize that the material parameters C, R, and L play important roles in generating energy from the solar cell; indeed, the stability increases with higher values of the converter capacitor and load inductance, whereas it decreases according to the resistive load. A number of periodic windows have been observed and the output frequency gives a broad-band spectrum of up to 50 kHz.

  9. A quenched c = 1 critical matrix model

    SciTech Connect

    Qiu, Zongan; Rey, Soo-Jong

    1990-12-01

    We study a variant of the Penner-Distler-Vafa model, proposed as a c = 1 quantum gravity: `quenched` matrix model with logarithmic potential. The model is exactly soluble, and exhibits a two-cut branching as observed in multicritical unitary matrix models and multicut Hermitian matrix models. Using analytic continuation of the power in the conventional polynomial potential, we also show that both the Penner-Distler-Vafa model and our `quenched` matrix model satisfy Virasoro algebra constraints.

  10. A quenched c = 1 critical matrix model

    SciTech Connect

    Qiu, Zongan; Rey, Soo-Jong.

    1990-12-01

    We study a variant of the Penner-Distler-Vafa model, proposed as a c = 1 quantum gravity: quenched' matrix model with logarithmic potential. The model is exactly soluble, and exhibits a two-cut branching as observed in multicritical unitary matrix models and multicut Hermitian matrix models. Using analytic continuation of the power in the conventional polynomial potential, we also show that both the Penner-Distler-Vafa model and our quenched' matrix model satisfy Virasoro algebra constraints.

  11. Voltage-To-Frequency Converter For Pressure Calibration

    NASA Technical Reports Server (NTRS)

    Sealey, Bradley S.; Mitchell, Michael

    1993-01-01

    Measurements of pressures on walls of wind tunnels and on surfaces of models in wind tunnels made with help of electronically scanned pressure-measurement (ESP) system. Voltage-to-frequency converter circuit, designed to convert 0- to 5-Vdc analog output voltage from high-line-pressure, low-differential-pressure standard to required frequency range. Enables selection of wider variety of high-accuracy pressure standards to enhance accuracy of measurement of ESP instrumentation while requiring little modification of manufacturer's system and no modification of operating software of system. Useful primarily in wind-tunnel instrumentation and readily adaptable to commercial instruments currently in use.

  12. Method for converting sucrose to .beta.-D-glucose

    DOEpatents

    Simmons, Blake A.; Volponi, Joanne V.; Ingersoll, David; Walker, Andrew

    2009-07-07

    Disclosed is an apparatus and method for continuously converting sucrose to .beta.-D-glucose. The method comprises a three-stage enzymatic reactor in which an aqueous solution of sucrose is first converted into a solution of fructose and .alpha.-D-glucose by passing it through a porous, packed column containing an inert media on which invertase is immobilized. This solution is then sent through a second packed column containing glucose isomerase and finally a third packed column containing mutarotase. Solution temperature and pH are adjusted to maximize glucose output.

  13. Resolver to 360.degree. linear analog converter and method

    NASA Technical Reports Server (NTRS)

    Alhorn, Dean C. (Inventor); Howard, David E. (Inventor); Smith, Dennis A. (Inventor)

    2000-01-01

    The converter produces a linear analog signal that is linearly proportional to a shaft angle of a resolver over 360.degree.. An excitation cosine signal supplied to the resolver and a response cosine signal received from the output windings of the resolver are converted to logic level signals. Digital logic is performed on the logic level signals in a programmable digital logic device to produce a logic level pulse-width modulated signal. The logic level pulse-width modulated signal is used to control a switch to switch between two reference voltage levels to produce a pulse-width modulated signal, which is filtered and buffered to produce the linear analog signal.

  14. An Electronic Ballast Using Back-boost Converter

    NASA Astrophysics Data System (ADS)

    Yokozeki, I.; Kato, Y.; Kuratani, T.; Okamura, Y.; Ohkita, M.; Takahashi, N.

    The new circuit of the electronic ballast for a fluorescent lamp, which is based on the back-boost converter, is proposed. This circuit has the advantage further than the circuit that combined the converter for rectification with the inverter for lighting in some points. Those advantages are reduction of the number of elements and improvement in the circuit efficiency, etc. And this circuit also satisfies regulation value of IEC class C on the relative harmonic contents of input current. From experimental results, the effectiveness of the proposed circuit is shown.

  15. Low Temperature Operation of a Switching Power Converter

    NASA Technical Reports Server (NTRS)

    Anglada-Sanchez, Carlos R.; Perez-Feliciano, David; Ray, Biswajit

    1997-01-01

    The low temperature operation of a 48 W, 50 kHz, 36/12 V pulse width modulated (PWM) buck de-de power converter designed with standard commercially available components and devices is reported. The efficiency of the converter increased from 85.6% at room temperature (300 K) to 92.0% at liquid nitrogen temperature (77 K). The variation of power MOSFET, diode rectifier, and output filter inductor loss with temperature is discussed. Relevant current, voltage. and power waveforms are also included.

  16. Process for converting cellulosic materials into fuels and chemicals

    DOEpatents

    Scott, Charles D.; Faison, Brendlyn D.; Davison, Brian H.; Woodward, Jonathan

    1994-01-01

    A process for converting cellulosic materials, such as waste paper, into fuels and chemicals utilizing enzymatic hydrolysis of the major constituent of paper, cellulose. A waste paper slurry is contacted by cellulase in an agitated hydrolyzer. The cellulase is produced from a continuous, columnar, fluidized-bed bioreactor utilizing immobilized microorganisms. An attritor and a cellobiase reactor are coupled to the agitated hydrolyzer to improve reaction efficiency. The cellulase is recycled by an adsorption process. The resulting crude sugars are converted to dilute product in a fluidized-bed bioreactor utilizing microorganisms. The dilute product is concentrated and purified by utilizing distillation and/or a biparticle fluidized-bed bioreactor system.

  17. Low dose failures of hardened DC-DC power converters

    NASA Technical Reports Server (NTRS)

    Lehman, J.; Yui, C.; Rax, B. G.; Miyahira, T. F.; Weideman, M.; Schrick, P.; Swift, G. M.; Johnston, A. H.

    2002-01-01

    Box-level total dose testing of the FOG (Fiber Optic Gyro) by IXSEA at ESA's GammabeamFacility were abruptly terminated at 8krad (Si) due to catastrophic failure (complete shutdown). This was unexpected because all components within the gyro were supposedly radiation tolerant. Further testing showed that the components responsible for the failure were two DC-DC converters, manufactured by Interpoint, that stopped regulating shortly before shutdown. This paper summarizes diagnostic test results for the converters to determine the underlying cause of the unexpected failure at low levels of radiation.

  18. A 25-kW Series-Resonant Power Converter

    NASA Technical Reports Server (NTRS)

    Frye, R. J.; Robson, R. R.

    1986-01-01

    Prototype exhibited efficiency of 93.9 percent. 25-kW resonant dc/dc power converter designed, developed, fabricated, and tested, using Westinghouse D7ST transistors as high-power switches. D7ST transistor characterized for use as switch in series-resonant converters, and refined base-drive circuit developed. Technical base includes advanced switching magnetic, and filter components, mathematical circuit models, control philosophies, and switch-drive strategies. Power-system benefits such as lower losses when used for high-voltage distribution, and reduced magnetics and filter mass realized.

  19. Gas-regulated cesium vapor source for thermionic converters

    NASA Astrophysics Data System (ADS)

    Kalandarishvili, A. G.; Chilingarishvili, P. D.

    1985-12-01

    Two types of gas-regulated Cs vapor sources have been tested in operation with model thermionic converters with cylindrical electrodes, and experimental results are given in terms of output power vs auxiliary gas pressure for several thermal powers delivered to the vaporizer. It is shown that nearly flat dependence can be achieved by suitably choosing the operating conditions of the source and by modifying the design of the vapor outlet, thus providing an easy method for stabilizing the operating parameters of the thermionic converter.

  20. Liquid metal thermal-electric converter electrode development

    SciTech Connect

    Martinez, J.I.

    1988-02-01

    This report describes work done in support of distributed receiver technology development. Dish-electric systems are being pursued in an effort to circumvent the need for energy transport by providing for heat-to-electricity energy conversion by individual heat engines at the focal point of parabolic dish concentrators. The Liquid Metal Thermal-Electric Converter is an engine that can convert thermal energy to electricity without the need for moving parts. The report documents the results of contracted work in the development of a long-lifetime, high-performance electrode for LMTEC, including the materials prepared for it. 17 refs., 20 figs., 3 tabs.