WorldWideScience

Sample records for hf power percentage

  1. Physics of the Geospace Response to Powerful HF Radio Waves

    Science.gov (United States)

    2012-10-31

    studies of the response of the Earth’s space plasma to high-power HF radio waves from the High-frequency Active Auroral Research Program ( HAARP ...of HF heating and explored to simulate artificial ducts. DMSP- HAARP experiments revealed that HF-created ion outflows and artificial density ducts...in the topside ionosphere appeared faster than predicted by the models, pointing to kinetic (suprathermal) effects. CHAMP/GRACE- HAARP experiments

  2. Power-Stepped HF Cross Modulation Experiments at HAARP

    Science.gov (United States)

    Greene, S.; Moore, R. C.; Langston, J. S.

    2013-12-01

    High frequency (HF) cross modulation experiments are a well established means for probing the HF-modified characteristics of the D-region ionosphere. In this paper, we apply experimental observations of HF cross-modulation to the related problem of ELF/VLF wave generation. HF cross-modulation measurements are used to evaluate the efficiency of ionospheric conductivity modulation during power-stepped modulated HF heating experiments. The results are compared to previously published dependencies of ELF/VLF wave amplitude on HF peak power. The experiments were performed during the March 2013 campaign at the High Frequency Active Auroral Research Program (HAARP) Observatory. HAARP was operated in a dual-beam transmission format: the first beam heated the ionosphere using sinusoidal amplitude modulation while the second beam broadcast a series of low-power probe pulses. The peak power of the modulating beam was incremented in 1-dB steps. We compare the minimum and maximum cross-modulation effect and the amplitude of the resulting cross-modulation waveform to the expected power-law dependence of ELF/VLF wave amplitude on HF power.

  3. Hardness and Second Phase Percentage of Ni-Ti-Hf Compounds After Heat Treatment at 700C

    Science.gov (United States)

    Stanford, Malcolm K.

    2017-01-01

    The Vickers hardness and second phase precipitation of three ternary intermetallic Ni-Ti-Hf compounds containing either 1, 3 or 5 at.% Hf were compared to 60-Nitinol (55 at.% Ni - 45 at.% Ti). Heat treatment either at 700 C or with a subsequent aging step, hardened the 3 and 5 at.% Hf-containing ternaries to approximately 620 HV (56 HRC). Heat treatment increased the hardness of the 1 at.% Hf compound by more than 25 percent. Average hardness of the 3 and 5 at.% Hf ternaries, though higher than that of the binary Ni-Ti or the Ni-Ti-Hf compound containing 1 at.% Hf, appeared to be fairly insensitive to the different heat treatments. There was a drastic reduction of fatigue-enhancing second phase precipitates for the 5 at.% Hf ternaries compared to the other compounds. These results should guide materials selection for development of aerospace componentry.

  4. Computational prediction for emission energy of iridium (III) complexes based on TDDFT calculations using exchange-correlation functionals containing various HF exchange percentages.

    Science.gov (United States)

    Xu, Shengxian; Wang, Jinglan; Xia, Hongying; Zhao, Feng; Wang, Yibo

    2015-02-01

    The accurate prediction for the emission energies of the phosphorescent Ir (III) complexes is very useful for the realizing of full-color displays and large-area solid-state lighting in OLED fields. Quantum chemistry calculations based on TDDFT methods are most widely used to directly compute the triplet vertical excitation energies, yet sometimes the universality of these calculations can be limited because of the lack of experimental data for the relative family of structural analogues. In this letter, 16 literature emission energies at low temperature are linearly correlated with their theoretical values computed by TDDFT using exchange-correlation functionals containing various HF exchange percentage with the relation of E exp (em)  = 1.2Ē calc (em). The relation is proven to be robust across a wide range of structures for Ir (III) complexes. These theoretical studies should be expected to provide some guides for the design and synthesis of efficient emitting materials.

  5. Integrated magnetics design for HF-link power converters

    DEFF Research Database (Denmark)

    Ljusev, Petar; Andersen, Michael Andreas E.

    2005-01-01

    This paper deals with the design of integrated magnetics for HF-link converters, where the integrated magnetic components do not necessarily belong to the same voltage loop. Depending on the specific HF-link converter topology, the proposed integrated magnetics can either alleviate the derivation...... of independent auxiliary supply voltages from the main transformer or integrate other magnetic structures, thus saving board space and cutting costs....

  6. Integrated magnetics design for HF-link power converters

    Energy Technology Data Exchange (ETDEWEB)

    Ljusev, P.; Andersen, Michael A.E.

    2005-07-01

    This paper deals with the design of integrated magnetics for HF-link converters, where the two integrated magnetic components on the same core do not necessarily belong to the same voltage loop. Depending on the specific HF-link converter topology, the proposed integrated magnetics can either alleviate the derivation of independent auxiliary supply voltages from the main transformer or integrate other magnetic structures, thus saving board space and cutting costs. (au)

  7. Power-Stepped HF Cross-Modulation Experiments: Simulations and Experimental Observations

    Science.gov (United States)

    Greene, S.; Moore, R. C.

    2014-12-01

    High frequency (HF) cross modulation experiments are a well established means for probing the HF-modified characteristics of the D-region ionosphere. The interaction between the heating wave and the probing pulse depends on the ambient and modified conditions of the D-region ionosphere. Cross-modulation observations are employed as a measure of the HF-modified refractive index. We employ an optimized version of Fejer's method that we developed during previous experiments. Experiments were performed in March 2013 at the High Frequency Active Auroral Research Program (HAARP) observatory in Gakona, Alaska. During these experiments, the power of the HF heating signal incrementally increased in order to determine the dependence of cross-modulation on HF power. We found that a simple power law relationship does not hold at high power levels, similar to previous ELF/VLF wave generation experiments. In this paper, we critically compare these experimental observations with the predictions of a numerical ionospheric HF heating model and demonstrate close agreement.

  8. Ionizing wave via high-power HF acceleration

    CERN Document Server

    Mishin, Evgeny

    2010-01-01

    Recent ionospheric modification experiments with the 3.6 MW transmitter at the High Frequency Active Auroral Research Program (HAARP) facility in Alaska led to discovery of artificial ionization descending from the nominal interaction altitude in the background F-region ionosphere by ~60 km. This paper presents a physical model of an ionizing wavefront created by suprathermal electrons accelerated by the HF-excited plasma turbulence.

  9. Ionizing wave via high-power HF acceleration

    OpenAIRE

    Mishin, Evgeny; Pedersen, Todd

    2010-01-01

    Recent ionospheric modification experiments with the 3.6 MW transmitter at the High Frequency Active Auroral Research Program (HAARP) facility in Alaska led to discovery of artificial ionization descending from the nominal interaction altitude in the background F-region ionosphere by ~60 km. This paper presents a physical model of an ionizing wavefront created by suprathermal electrons accelerated by the HF-excited plasma turbulence.

  10. Ionospheric Modification from Under-Dense Heating by High-Power HF Transmitter

    Science.gov (United States)

    2011-03-03

    Auroral Research Program ( HAARP ) is a HF transmitter, which delivers 0.36 to 3.6 GW effective isotropic radiated powers (F.IRP) for the radiation...dense heating, the EIRP of the HAARP heater can be increased significantly by increasing the heater frequency. With higher heater frequency, the loss...1304 local time) and on 13 April from 0812 to 0844 UTC (0012 to 0044 local time), using the HAARP transmitter facility at Gakona, AK, at full power

  11. Studies of Plasma Instability Process Excited by Ground Based High Power HF (Heating) Facilities

    Science.gov (United States)

    2007-11-02

    the altitude z = 285 km. Night time plasma line intensities were observed to be enhanced by a factor 10 ÷ 100 extended to altitude below 250 km. When HF...waves, whose wave vector is directed toward the radar, and the phase velocity vph is equal to the velocity of suprathermal electrons v vph =(1/2) λr...averaged and in final form depends on two scalar factors only: full power density P absorbed by fast electrons in the acceleration layer, and characteristic

  12. Modelling of energy systems with a high percentage of CHP and wind power

    DEFF Research Database (Denmark)

    Lund, Henrik; Münster, E.

    2003-01-01

    The paper presents the energy system analysis model EnergyPLAN, which has been used to analyse the integration of large scale wind power into the national Danish electricity system. The main purpose of the EnergyPLAN model is to design suitable national energy planning strategies by analysing the...

  13. Deposition-power-modulated optical and electrical properties of sputtering-derived HfTiO{sub x} gate dielectrics

    Energy Technology Data Exchange (ETDEWEB)

    Jin, P. [School of Physics and Materials Science, Radiation Detection Materials & Devices Lab, Anhui University, Hefei, 230601 (China); He, G., E-mail: cheriling16@126.com [School of Physics and Materials Science, Radiation Detection Materials & Devices Lab, Anhui University, Hefei, 230601 (China); Liu, M. [Key Laboratory of Materials Physics, Anhui Key Laboratory of Nanomaterials and, Nanostructure, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei, 230031 (China); Xiao, D.Q.; Gao, J.; Chen, X.F. [School of Physics and Materials Science, Radiation Detection Materials & Devices Lab, Anhui University, Hefei, 230601 (China); Ma, R. [Key Laboratory of Materials Physics, Anhui Key Laboratory of Nanomaterials and, Nanostructure, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei, 230031 (China); Zhang, J.W.; Zhang, M.; Sun, Z.Q.; Liu, Y.M. [School of Physics and Materials Science, Radiation Detection Materials & Devices Lab, Anhui University, Hefei, 230601 (China)

    2015-11-15

    High-k gate dielectric HfTiO{sub x} thin films have been deposited on Si and quartz substrate by radio frequency (RF) magnetron sputtering. The structural and optical properties of HfTiO{sub x} thin films related to deposition power are investigated by X-ray diffraction (XRD), ultraviolet–visible spectroscopy (UV–Vis), and spectroscopic ellipsometry (SE). Results indicate that the as-deposited HfTiO{sub x} thin films are amorphous state regardless of the deposition power. The increase of band gap of the samples is observed with the increase of deposition power. Moreover, the increase of the thickness, deposition rate, refractive index (n) and the decrease of the extinction coefficient with the increase of deposition power are also confirmed. Additionally, the electrical properties of films are analyzed by measurement of high frequency capacitance–voltage (C–V) and leakage current density-voltage (J-V) characteristics. And the leakage current conduction mechanisms are also discussed. - Highlights: • Sputtering-derived HfTiO{sub x} gate dielectrics have been deposited on Si substrates. • Increase of band gap is observed with the increase of deposition power. • HfTiO{sub x} thin film deposited at 50 W displays excellent performance. • The leakage current conduction mechanisms are also discussed in detail.

  14. Phenomena in the ionosphere-magnetosphere system induced by injection of powerful HF radio waves into nightside auroral ionosphere

    Directory of Open Access Journals (Sweden)

    N. F. Blagoveshchenskaya

    2005-01-01

    Full Text Available Experimental results from three ionospheric HF pumping experiments in overdense E or F regions are summarized. The experiments were conducted by the use of the EISCAT HF Heating facility located near Tromsø, Norway, allowing HF pumping the ionosphere in a near geomagnetic field-aligned direction. Distinctive features related to auroral activations in the course of the experiments are identified. Typical features observed in all experiments are the following: generation of scattered components in dynamic HF radio scatter Doppler spectra; strong increase of ion temperatures Ti and local ionospheric electric field E0; modification of the auroral arc and local spiral-like formation. However, some effects were observed only when the HF pump wave was reflected from the F2 layer. Among them are the generation of intense field-aligned ion outflows, and a strong increase in the electron temperature Te with altitude. A possible scenario for the substorm triggering due to HF pumping into an auroral ionosphere is discussed. The authors present their interpretation of the data as follows. It is suggested that two populations of charged particles are at play. One of them is the runaway population of electrons and ions from the ionosphere caused by the effects of the powerful HF radio wave. The other is the population of electrons that precipitate from the magnetosphere. It is shown that the hydrodynamical equilibrium was disrupted due to the effects of the HF pumping. We estimate that the parallel electric field can reach values of the order of 30mV/m during substorm triggering.

  15. HF power couplers for pulsed superconducting cavity resonators; Coupleurs de puissance HF pour cavites supraconductrices en mode pulse

    Energy Technology Data Exchange (ETDEWEB)

    Jenhani, Hassen [Laboratoire de l' Accelerateur Lineaire, IN2P3-CNRS et Universite de Paris-Sud, BP 34, F-91898 Orsay Cedex (France)

    2006-11-15

    Recent years have seen an impressive improvement in the accelerating gradients obtained in superconducting cavities. Consequently, such cavities have become attractive candidates for large superconducting linear accelerator projects such as the European XFEL and the International Linear Collider (ILC). As a result, there is a strong interest in reducing RF conditioning time and improving the performance of the input power couplers for these cavities. The so-called TTF-III input power coupler, adopted for the XFEL superconducting RF cavities are complex components. In order to better understand the behavior of this component we have performed a series of experiments on a number of such couplers. Initially, we developed a fully automated RF high power test stand for coupler conditioning procedure. Following this, we performed a series of coupler conditioning tests. This has allowed the study of the coupler behavior during processing. A number of experiments were carried out to evaluate the in-situ baking effect on the conditioning time. Some of the conditioned couplers were sent to DESY in order to be tested on 9-cells TESLA cavities under cryogenic conditions. These tests have shown that the couplers in no way limit the cavity performance, even up to gradients of 35 MV/m. The main objective of our coupler studies was the reduction of their conditioning time, which represents one of the most important criteria in the choice of coupler for high energy linacs. Excellent progress in reducing the conditioning time has been demonstrated by making appropriate modifications to the conditioning procedure. Furthermore, special attention was paid to electron generation processes in the couplers, via multipacting. Simulations of this process were made on both the TTF-III coupler and on a new coupler prototype, TTF-V. Experiments aimed at suppressing multipacting were also successfully achieved by using a DC bias on the inner conductor of the co-axial coupler. (author)

  16. Geometric Aspects of Artificial Ionospheric Layers Driven by High-Power HF-Heating

    Science.gov (United States)

    Milikh, G. M.; Eliasson, B.; Shao, X.; Djordjevic, B.; Mishin, E. V.; Zawdie, K.; Papadopoulos, K.

    2013-12-01

    We have generalized earlier developed multi-scale dynamic model for the creation and propagation of artificial plasma layers in the ionosphere [Eliasson et al, 2012] by including two dimensional effects in the horizontal direction. Such layers were observed during high-power high frequency HF heating experiments at HAARP [Pedersen et al., 2010]. We have numerically investigated the importance of different angles of incidence of ordinary mode waves on the Langmuir turbulence and the resulting electron acceleration that leads to the formation of artificial ionospheric layers. It was shown that the most efficient electron acceleration and subsequent ionization is obtained at angles between magnetic zenith and the vertical, where strong Langmuir turbulence dominates over weak turbulence. A role played by the heating wave propagation near caustics was also investigated. Eliasson, B. et al. (2012), J. Geophys. Res. 117, A10321, doi:10.1029/2012JA018105. Pedersen, T., et al. (2010), Geophys. Res. Lett., 37, L02106, doi:10.1029/2009GL041895.

  17. Creation of Artificial Ionospheric Layers Using High-Power HF Waves

    Science.gov (United States)

    2010-01-30

    Program ( HAARP ) transmitter in Gakona, Alaska. The HF- driven ionization process is initiated near the 2nd electron gyroharmonic at 220 km altitude in...the 3.6 MW High-Frequency Active Auroral Program ( HAARP ) transmitter in Gakona, Alaska. The HF-driven ionization process is initiated near the 2nd...Maine. USA. Copyright 2010 by the American Geophysical Union. 0094-8276/I0/2009GLO41895SO5.0O Research Program ( HAARP ) transmitter facility, however

  18. Excitation of small-scale waves in the F region of the ionosphere by powerful HF radio waves

    Science.gov (United States)

    Blagoveshchenskaya, N. F.; Chernyshev, M. Y.; Kornienko, V. A.

    1998-01-01

    Ionospheric small-scale waves in the F region, initiated by heating facilities in Nizhniy Novgorod, have been studied by the method of field-aligned scattering of diagnostic HF radio signals. Experimental data have been obtained on the radio path Kiev-N. Novgorod-St. Petersburg during heating campaigns with heater radiated power ERP = 20 MW and 100 MW. Observations of scattered HF signals have been made by a Doppler spectrum device with high temporal resolution. Analysis of the experimental data shows a relation between the heater power level and the parameters of ionospheric small-scale oscillations falling within the range of Pc 3-4 magnetic pulsations. It is found that the periods of wave processes in the F region of the ionosphere, induced by the heating facility, decrease with increasing heating power. The level of heating power also has an impact on the horizontal east-west component of the electric field E, the vertical component of the Doppler velocity Vd and the amplitude of the vertical displacements M of the heated region. Typical magnitudes of these parameters are the following: E = 1.25 mVm, Vd = 6 ms, M = 600-1500 m for ERP = 20 MW and E = 2.5-4.5 mVm, Vd = 11-25 ms, M = 1000-5000 m for ERP = 100 MW. The results obtained confirm the hypothesis of excitation of the Alfvén resonator by powerful HF radio waves which leads to the generation of magnetic field oscillations in the heated region giving rise to artificial Pc 3-4 magnetic pulsations and ionospheric small-scale wave processes. In this situation an increase of the heater power would lead to a growth of the electric field of hydromagnetic waves propagating in the ionosphere as well as the amplitude of the vertical displacements of the heated region.

  19. Ionosonde Studies of Field-Aligned Irregularities during High-Power HF Heating at Arecibo,

    Science.gov (United States)

    1988-02-01

    September 1981 ionospheric HF heating campaign at Arecibo have been simulated using simplified ionospheric models -’ and analytic raytracing techniques. The...R given by R = ((h )2 -(V ))/6B) NR h6B is the radar range of the oblique echoes and h ERT the virtual height of the overhead ionization measured at...However, the conditions of the Arecibo experiment are such that various simplifications can be made, including the adoption of analytic raytracing

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

    Science.gov (United States)

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

    2016-07-01

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

  1. Investigation of switching mechanism in HfOx-ReRAM under low power and conventional operation modes

    Science.gov (United States)

    Feng, Wei; Shima, Hisashi; Ohmori, Kenji; Akinaga, Hiroyuki

    2016-12-01

    Low-power resistive random access memory (LP-ReRAM) devices have attracted increasing attention owing to their advantages of low operation power. In this study, a vertical-type LP-ReRAM consisting of TiN/Ti/HfO2/TiN structure was fabricated. The switching mechanism for LP-ReRAM was elucidated as the conductive filament mechanism for conventional mode, and an interface-type switching mechanism for low power mode was proposed. The analysis of low frequency noise shows that power spectral density (PSD) is approximately proportional to 1/f for conventional operation mode. Nevertheless, for low power mode, the PSD of low resistance state (LRS) is proportional to 1/f, while that of high resistance state (HRS) is clear proportional to 1/f2. The envelope of multiple Lorentzian spectra of 1/f2 characteristics due to different traps reveals the characteristics of 1/f. For HRS of low power mode, a limited number of traps results in a characteristic of 1/f2. During the set process, the number of oxygen vacancies increases for LRS. Therefore, the PSD value is proportional to 1/f. Owing to the increase in the number of traps when the operation mode changes to conventional mode, the PSD value is proportional to 1/f. To the best of our knowledge, this is the first study that reveals the different noise characteristics in the low power operation mode from that in the conventional operation mode.

  2. Prompt Ion Outflows and Artificial Ducts during High-Power HF Heating at HAARP: Effect of Suprathermal Electrons?

    Science.gov (United States)

    Mishin, E. V.; Milikh, G. M.

    2014-12-01

    In situ observations from the DMSP and Demeter satellites established that high-power HF heating of the ionosphere F-region results in significant ion outflows associated with 10-30% density enhancements in the topside ionosphere magnetically-conjugate to the heated region. As follows from the SAMI2 two-fluid model calculations, their formation time should exceed 5-7 minutes. However, specially designed DMSP-HAARP experiments have shown that artificial ducts and ion outflows appear on the topside within 2 minutes. We describe the results of these observations and present a semi-quantitative explanation of the fast timescale due to suprathermal electrons accelerated by HF-induced plasma turbulence. There are two possible effects of suprathermal electrons: (1) the increase of the ambipolar electric field over the usual thermal ambipolar diffusion and (2) excitation of heat flux-driven plasma instability resulting in an anomalous electron-ion momentum exchange. Both effects result in faster upward ion flows.

  3. Percentage of beta 2 band power of quantitative pharmaco-electroencephalography decreases in propofol anesthetized rabbits A dose-dependent analysis

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    BACKGROUND:Quantitative pharmaco-electroencephalography can be used for studying the dose-effect and time-effect relationships of drugs affecting central nervous system.Therefore,it may become an effective means for monitoring the anesthetic degree of anesthetic drug in the operation.OBJECTIVE:To observe the dose-effect relationship of propofol influencing β2-band power of quantitative pharmaco-electroencephalography in rabbits.DESIGN:A randomized block design.SETTING:Department of Anesthesiology,Xuzhou Medical College.MATERIALS:Thirty-six healthy adult rabbits of either gender,weighing (2.4+0.5)kg,of clean grade,were provided by the Laboratory Animal Center of Xuzhou Medical College.The involved rabbits were randomly divided into 3 groups with 12 in each by table of random digit:high-dose propofol group,moderate-dose propofol group,and low-dose propofol group.The protocol was carried out in accordance with animal ethics guidelines for the use and care of animals.METHODS:This study was carried out in the Department of Anesthesiology,Xuzhou Medical College between August 1999 and April 2000.Rabbits in the high-dose propofol group,moderate-dose propofol group,and low-dose propofol group were injected with 10,5 and 2.5 mg/kg propofol (ZENECA Company,British,Batch No.032000),respectively.Before and after intravenous administration of propofol,percentage of β2-band power of quantitative pharmaco-electroencephalography was measured,and the latent and persistent periods when rabbit righting reflex disappeared were observed by quantitative pharmaco-electroencephalography and power spectrum analysis.MAIN OUTCOME MEASURES:① Percentage of β 2-band power of quantitative pharmaco-electroencephalography.②Latent period and persistent period of abolition of righting reflex of rabbits.RESULTS:Thirty-six rabbits were involved in the final analysis.①Effect of propofol on righting reflex of rabbits:Righting reflex disappeared within 1 minute after the rabbits being

  4. Resistive switching characteristic and uniformity of low-power HfO x -based resistive random access memory with the BN insertion layer

    Science.gov (United States)

    Su, Shuai; Jian, Xiao-Chuan; Wang, Fang; Han, Ye-Mei; Tian, Yu-Xian; Wang, Xiao-Yang; Zhang, Hong-Zhi; Zhang, Kai-Liang

    2016-10-01

    In this letter, the Ta/HfO x /BN/TiN resistive switching devices are fabricated and they exhibit low power consumption and high uniformity each. The reset current is reduced for the HfO x /BN bilayer device compared with that for the Ta/HfO x /TiN structure. Furthermore, the reset current decreases with increasing BN thickness. The HfO x layer is a dominating switching layer, while the low-permittivity and high-resistivity BN layer acts as a barrier of electrons injection into TiN electrode. The current conduction mechanism of low resistance state in the HfO x /BN bilayer device is space-charge-limited current (SCLC), while it is Ohmic conduction in the HfO x device. Project supported by the National Natural Science Foundation of China (Grant Nos. 61274113, 11204212, 61404091, 51502203, and 51502204), the Tianjin Natural Science Foundation, China (Grant Nos. 14JCZDJC31500 and 14JCQNJC00800), and the Tianjin Science and Technology Developmental Funds of Universities and Colleges, China (Grant No. 20130701).

  5. Percentage recovery of dioxin homologue through power-prep according to the eluting solvents and their amounts

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Tae-Uk [Gyeongsang National Univ., Jinju (Korea). Division of Applied Life Science]|[National Veterinary Research and Quarantine Service (Korea). Busan Regional Office; Kim, Dong-Gyu [National Veterinary Research and Quarantine Service (Korea). Seoul Regional Office; Choi, Si-Weon [National Veterinary Research and Quarantine Service (Korea). Busan Regional Office; Seo, Dong-Cheol; Jeo, Jong-Soo [Gyeongsang National Univ., Jinju (Korea). Division of Applied Life Science; Lee, Hong-Jae [Jinju National Univ. (Korea). Dept. of Environmental Engineering

    2004-09-15

    Because of the persistence and accumulation of polychlorinated dibenzo dioxins(PCDDs) and polychlorinated dibenzo furans(PCDFs) in the environment, dioxins contamination is regarded as a global issue. And various methods for analyzing PCDDs and PCDFs have been developed and improved. According to US EPA method, cleanup method was very various. Conventional cleanup methods are very dependable, but are time consuming and use large volumes of organic solvents. To increase the efficiency of cleanup for the analysis of PCDDs and PCDFs, we used high speed automated sample cleanup system for dioxins which is called Power-Prep trademark (Fluid Management System Inc., USA). Power- Prep trademark gave us swift analysis of dioxin and its precision and accuracy. This system was designed to cleanup of toxic compound such as dioxins, PCBs, pesticides and PAHs using silica, alumina and carbon column. Using this system, it is possible to conduct several samples in less than 1.5 hours, thereby, achieving high recoveries and excellent precision and accuracy for all dioxin congeners. In this experiment, we carried out PCDDs and PCDFs analysis by FMS(Fluid Management System Inc.) with 3 eluting solvents such as toluene, hexane and dichloromethane to find out the best eluting solvent and its amounts.

  6. Study of HF behaviour of railway power substation in reduced scale

    Science.gov (United States)

    Ouaddi, H.; Baranowski, S.; Nottet, G.; Demoulin, B.; Koné, L.

    2011-03-01

    The study presented in this paper is a first step of an EMC (Electromagnetic Compatibility) analysis of the behaviour of a railway power substation at high frequency. Before on site intensive experimentation, the approach is performed with a reduced scale model. The mock-up of the substation is powered by a 220 V three-phase voltage supplied by a 15 kV A power transformer, a rectifier and loads. The study consists in designing an equivalent electrical circuit of power transformer in high frequency, available over a large panel of loads. The model of power transformer was deduced from measurements in frequency domain within the range 40 Hz to 30 MHz.

  7. A medium-power small-scale slotted CO2 waveguide laser with HF excitation

    Science.gov (United States)

    Vitruk, P. P.; Iatsenko, N. A.

    1989-03-01

    Experimental results are reported on the high-frequency capacitive discharge (HFCD) regime of a medium-power small-scale slotted waveguide CO2 laser. An output power of 100-200 W at an electrooptical efficiency of 5-6 percent was obtained using a CO2:N2:He = 1:1:3 mixture at a pressure of 8-12 torr at a low gas flowrate (0.2 liter/min).

  8. Preliminary Study of Gas Cooled Fast Breeder Reactor with Heterogen Percentage of Uranium–Plutonium Carbide based fuel and 300 MWt Power

    Science.gov (United States)

    Clief Pattipawaej, Sandro; Su’ud, Zaki

    2017-01-01

    A preliminary design study of GFR with helium gas-cooled has been performed. In this study used natural uranium and plutonium results LWR waste as fuel. Fuel with a small percentage of plutonium are arranged on the inside of the core area, and the fuel with a greater percentage set on the outside of the core area. The configuration of such fuel is deliberately set to increase breeding in this part of the central core and reduce the leakage of neutrons on the outer side of the core, in order to get long-lived reactor with a small reactivity. Configuration of fuel as it is also useful to generate a peak power reactors with relatively low in both the direction of axial or radial. Optimization has been done to fuel fraction 45.0% was found that the reactor may be operating in more than 10 year time with excess reactivity less than 1%.

  9. Active implantable medical device EMI assessment for wireless power transfer operating in LF and HF bands

    Science.gov (United States)

    Hikage, Takashi; Nojima, Toshio; Fujimoto, Hiroshi

    2016-06-01

    The electromagnetic interference (EMI) imposed on active implantable medical devices by wireless power transfer systems (WPTSs) is discussed based upon results of in vitro experiments. The purpose of this study is to present comprehensive EMI test results gathered from implantable-cardiac pacemakers and implantable cardioverter defibrillators exposed to the electromagnetic field generated by several WPTSs operating in low-frequency (70 kHz-460 kHz) and high-frequency (6.78 MHz) bands. The constructed in vitro experimental test system based upon an Irnich’s flat torso phantom was applied. EMI test experiments are conducted on 14 types of WPTSs including Qi-compliant system and EV-charging WPT system mounted on current production EVs. In addition, a numerical simulation model for active implantable medical device (AIMD) EMI estimation based on the experimental test system is newly proposed. The experimental results demonstrate the risk of WPTSs emitting intermittent signal to affect the correct behavior of AIMDs when operating at very short distances. The proposed numerical simulation model is applicable to obtain basically the EMI characteristics of various types of WPTSs.

  10. High-power ELF radiation generated by modulated HF heating of the ionosphere can cause Earthquakes, Cyclones and localized heating

    OpenAIRE

    De Aquino, Fran

    2011-01-01

    The High Frequency Active Auroral Research Program (HAARP) is currently the most important facility used to generate extremely low frequency (ELF) electromagnetic radiation in the ionosphere. In order to produce this ELF radiation the HAARP transmitter radiates a strong beam of high-frequency (HF) waves modulated at ELF. This HF heating modulates the electrons' temperature in the D region ionosphere and leads to modulated conductivity and a time-varying current which then radiates at the modu...

  11. High-power ELF radiation generated by modulated HF heating of the ionosphere can cause Earthquakes, Cyclones and localized heating

    OpenAIRE

    De Aquino, Fran

    2011-01-01

    The High Frequency Active Auroral Research Program (HAARP) is currently the most important facility used to generate extremely low frequency (ELF) electromagnetic radiation in the ionosphere. In order to produce this ELF radiation the HAARP transmitter radiates a strong beam of high-frequency (HF) waves modulated at ELF. This HF heating modulates the electrons' temperature in the D region ionosphere and leads to modulated conductivity and a time-varying current which then radiates at the modu...

  12. Predicted and observed characteristics of small-scale field-aligned irregularities generated in the F-region by low power HF heating

    Directory of Open Access Journals (Sweden)

    E. Kolesnikova

    Full Text Available Simultaneous HF scattering from the different regions of the heated volume is used to investigate characteristics of the small-scale field-aligned irregularities in the F-region. Time of growth, decay rate and saturation level for different pump powers are deduced from the observations and are compared with their behaviour predicted by the thermal parametric instability model. As a result, the estimates of the density and of the temperature modifications inside of the irregularities are obtained.

    Key words. Ionosphere (ionospheric irregularities

  13. HF Interference, Procedures and Tools (Interferences HF, procedures et outils)

    Science.gov (United States)

    2007-06-01

    such sources. The existing HF background noise possibly may be increased via ground wave and/or sky wave propagation. Increase of the existing HF...télécommunications filaires à large bande. Les télécommunications via le réseau électrique courant, dites PowerLine Communications (PLT ou PLC) et diverses...cumulative de nombreuses sources de même type. Le bruit de fond HF existant risque d’être augmenté par propagation de l’onde terrestre et/ou aérienne

  14. Solving Problems with The Percentage Bar

    Directory of Open Access Journals (Sweden)

    Frans van Galen

    2013-01-01

    Full Text Available At the end of primary school all children more of less know what apercentage is, but yet they often struggle with percentage problems.This article describes a study in which students of 13 and 14 years old were given a written test with percentage problems and a week later were interviewed about the way they solved some of these problems. In a teaching experiment the students were then taught the use of the percentage bar. Although the teaching experiment was very short - just one lesson - the results confirm that the percentage bar is a powerful model that deserves a central place in the teaching of percentages

  15. A medium-power small-scale slotted CO/sub 2/ waveguide laser with HF excitation

    Energy Technology Data Exchange (ETDEWEB)

    Vitruk, P.P.; Iatsenko, N.A.

    1989-03-01

    Experimental results are reported on the high-frequency capacitive discharge (HFCD) regime of a medium-power small-scale slotted waveguide CO2 laser. An output power of 100-200 W at an electrooptical efficiency of 5-6 percent was obtained using a CO2:N2:He = 1:1:3 mixture at a pressure of 8-12 torr at a low gas flowrate (0.2 liter/min). 8 refs.

  16. Solving Problems with The Percentage Bar

    Directory of Open Access Journals (Sweden)

    Frans van Galen

    2013-01-01

    Full Text Available At the end of primary school all children more of less know what a percentage is, but yet they often struggle with percentage problems. This article describes a study in which students of 13 and 14 years old were given a written test with percentage problems and a week later were interviewed about the way they solved some of these problems. In a teaching experiment the students were then taught the use of the percentage bar. Although the teaching experiment was very short - just one lesson  -  the results confirm that the percentage bar is a powerful model that deserves a central place in the teaching of percentages.Keywords: percentage, model, design research DOI: http://dx.doi.org/10.22342/jme.4.1.558.1-8

  17. Polarization features of the ELF emissions excited in the outer ionosphere through modification of the ionospheric F-region by high-power HF radio emission

    Science.gov (United States)

    Belov, Alexey

    indent=1cm The results of in-situ measurements performed by the onboard equipment of the DEMETER satellite show that the guided ELF emissions can be excited through modification of the ionospheric F-region by high-power HF radio emission from the SURA heating facility. The power spectra of the excited ELF waves have a sharp upper frequency cutoff at the local proton gyrofrequency. In this work, we study the propagation and polarization characteristics of the observed ELF emissions using multicomponent measurement of electric and magnetic fields from the DEMETER satellite. For analysis we make use of singular value decomposition (SVD) technique. It is shown that the polar angle of the observed emissions wave vector with respect to ambient magnetic field is less than pi/6. The waves propagate upward in the left-hand-polarized mode. The wave polarization changes from right- to left-handed at the so-called crossover frequency. The obtained results improve the understanding of the generation mechanisms of observed ELF emissions. This work was supported by the Russian Foundation for Basic Research (project No. 12-02-00747-a), and the Government of the Russian Federation (contract No. 11.G34.31.0048).

  18. Physical and electrical properties of induced high-k ZrHfO crystallization with ZrN cap by high power impulse magnetron sputtering for metal-gate metal-insulator-semiconductor structures

    Science.gov (United States)

    Tsai, Jung-Ruey; Juan, Pi-Chun; Lin, Cheng-Li; Lin, Guo-Cheng

    2017-01-01

    Metal-gate TiN/ZrN/ZrHfO/p-Si metal-insulator-semiconductor (MIS) structures have been fabricated in this work. The physical and electrical properties were characterized. The crystallization of high-k ZrHfO thin-film is induced by high power impulse magnetron sputtering (HIPIMS) during the deposition of ZrN capping layer. The binding energies and depth profiles were investigated by X-ray photoelectron spectroscopy (XPS). It is found that Zr and Hf out-diffusion from high-k dielectric in samples with HIPIMS is lesser than those in samples with the conventional DC magnetron sputtering (DCMS). The dielectric constant which strongly relates to the tetragonal phase becomes higher and the flatband voltage shift shows smaller by using the HIPIMS method than by the conventional DCMS. The cation and anion vacancies have been investigated by the defect reaction model.

  19. Effects of midazolam on the percentage of δ band power of quantitative pharmaco-EEG%咪达唑仑对人定量药物脑电图δ频段功率百分比的影响

    Institute of Scientific and Technical Information of China (English)

    王立伟; 戴体俊; 王建华; 张党生; 周美艳

    2011-01-01

    Aim To investigate the effects of midazolam on the percentage of δ band power of quantitative pharmco-EEG( QPEEG ). Methods 20 healthy male adults were randomly divided into 2 groups ( n= 10 each ) and were given iv injections of 0.05 mg · kg-1 and 0. 1 mg · kg-1 of midazolam respectively. The EEG samples were obtained before and at regular intervals following the midazolam injections. Power spectral analysis was conducted to check the EEG variations before and after the midazolam iv injections. Results After midazolam injections, the percentage of δ band power of QPEEG all increased in group Ⅱ( P <0.01 ),reached its peak after about 5 min, and then returned to normal after about 10 min. The percentage of δ bandpower of QPEEG had a trend of increase in group Ⅰ ,but was not statistically significant ( P > 0.05 ). Conclusions Midazolam increases the percentage of QPEEG power at δ band in a dose-dependent manner,which suggests that the percentage of QPEEG power at δ band serves as an effective index of anesthesia depth monitering.%目的 观察咪达唑仑对人定量药物脑电图(QPEEG)δ频段功率百分比的影响.方法 青年志愿者20人,每组10人,均为男性,分别静脉注射咪达唑仑0.05 mg·kg-1(Ⅰ组)、0.1 mg·kg-1(Ⅱ组),观察比较2组给药前后QPEEG的δ频段功率百分比.结果 注射咪达唑仑后,Ⅱ组各导联QPEEG δ频段功率百分比均增加(P0.05).结论 咪达唑仑可剂量依赖性地增加人QPEEG δ频段功率百分比,提示QPEEG δ频段功率百分比可能成为监测咪达唑仑麻醉深度的指标.

  20. The influence of 175 MeV nickel ion irradiation on the electrical characteristics of power transistors (HF13)

    Science.gov (United States)

    Pushpa, N.; Praveen, K. C.; Gnana Prakash, A. P.; Naik, P. S.; Gupta, S. K.; Revannasiddaiah, D.

    2012-10-01

    The dc electrical characteristics of NPN RF power transistors were studied systematically before and after 175 MeV Ni13+ ion and Co-60 gamma irradiation in the dose range from 100 krad to 100 Mrad. The transistor parameters such as excess base current (ΔIB= IBpost-IBpre), dc current gain (hFE), and collector-saturation current (ICSat) were studied. The base current (IB) was found to increase significantly after irradiation and this in turn decreases the hFE of the transistors. Further, the output characteristics of the irradiated devices exhibit the decrease in the collector current at the saturation region (ICSat) with increase of radiation dose.

  1. Phenomena induced by powerful HF pumping towards magnetic zenith with a frequency near the F-region critical frequency and the third electron gyro harmonic frequency

    Directory of Open Access Journals (Sweden)

    N. F. Blagoveshchenskaya

    2009-01-01

    Full Text Available Multi-instrument observational data from an experiment on 13 October 2006 at the EISCAT/HEATING facility at Tromsø, Norway are analysed. The experiment was carried out in the evening hours when the electron density in the F-region dropped, and the HF pump frequency fH was near and then above the critical frequency of the F2 layer. The distinctive feature of this experiment is that the pump frequency was just below the third electron gyro harmonic frequency, while both the HF pump beam and UHF radar beam were directed towards the magnetic zenith (MZ. The HF pump-induced phenomena were diagnosed with several instruments: the bi-static HF radio scatter on the London-Tromsø-St. Petersburg path, the CUTLASS radar in Hankasalmi (Finland, the European Incoherent Scatter (EISCAT UHF radar at Tromsø and the Tromsø ionosonde (dynasonde. The results show thermal electron excitation of the HF-induced striations seen simultaneously from HF bi-static scatter and CUTLASS radar observations, accompanied by increases of electron temperature when the heater frequency was near and then above the critical frequency of the F2 layer by up to 0.4 MHz. An increase of the electron density up to 25% accompanied by strong HF-induced electron heating was observed, only when the heater frequency was near the critical frequency and just below the third electron gyro harmonic frequency. It is concluded that the combined effect of upper hybrid resonance and gyro resonance at the same altitude gives rise to strong electron heating, the excitation of striations, HF ray trapping and extension of HF waves to altitudes where they can excite Langmuir turbulence and fluxes of electrons accelerated to energies that produce ionization.

  2. Pulsed inductive HF laser

    Energy Technology Data Exchange (ETDEWEB)

    Razhev, A M; Kargapol' tsev, E S [Institute of Laser Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation); Churkin, D S; Demchuk, S V [Novosibirsk State University, Novosibirsk (Russian Federation)

    2016-03-31

    We report the results of experimentally investigated dependences of temporal, spectral and spatial characteristics of an inductive HF-laser generation on the pump conditions. Gas mixtures H{sub 2} – F{sub 2}(NF{sub 3} or SF6{sub 6}) and He(Ne) – H{sub 2} – F{sub 2}(NF{sub 3} or SF{sub 6}) were used as active media. The FWHM pulse duration reached 0.42 μs. This value corresponded to a pulsed power of 45 kW. For the first time, the emission spectrum of an inductive HF laser was investigated, which consisted of seven groups of bands with centres around the wavelengths of 2732, 2736, 2739, 2835, 2837, 2893 and 2913 nm. The cross section profile of the laser beam was a ring with a diameter of about 20 mm and width of about 5 mm. Parameters of laser operation in the repetitively pulsed regime were sufficiently stable. The amplitude instability of light pulses was no greater than 5% – 6%. (lasers)

  3. HF radiation emitted by chaotic leader processes

    Science.gov (United States)

    Mäkelä, J. S.; Edirisinghe, M.; Fernando, M.; Montaño, R.; Cooray, V.

    2007-04-01

    This paper presents direct measurements of narrowband 10 MHz HF radiation from so-called “chaotic leaders” associated with subsequent return strokes. Although the term is controversial and poorly defined, we find that more than 30% of subsequent strokes in close lightning flashes contain electric field characteristics that are best described as “chaotic”. In earlier studies, return strokes have consistently been observed to be the strongest sources of HF radiation, but the results for leader processes are less consistent. We also observe return strokes to be the main HF emitter, and the leaders before the first return stroke in a flash sequence also emit HF though somewhat less intensely. The leaders preceding subsequent strokes typically emit little or no HF radiation, whether they are dart or dart-stepped leaders. However, it was observed that the presence of a chaotic component increases the leader HF intensity dramatically Defining the HF intensity unequivocally can be problematic for processes like chaotic leaders which have a combination of continuous and impulsive phenomena. Two time-domain methods were used to measure the HF intensity, the peak energy and the RMS energy. In the frequency domain these correspond to the energy spectral density (ESD) and power spectral density (PSD), respectively. It was found that the methods are not necessarily compatible. Thus, it is suggested that to clarify future work, leader processes should be characterized by the PSD rather than the ESD.

  4. ExtraHF survey

    DEFF Research Database (Denmark)

    Piepoli, Massimo F; Binno, Simone; Corrà, Ugo

    2015-01-01

    AIMS: In heart failure (HF), exercise training programmes (ETPs) are a well-recognized intervention to improve symptoms, but are still poorly implemented. The Heart Failure Association promoted a survey to investigate whether and how cardiac centres in Europe are using ETPs in their HF patients...... of evidence on safety or benefit was cited. When implemented, an ETP was proposed to all HF patients in only 55% of the centres, with restriction according to severity or aetiology. CONCLUSIONS: With respect to previous surveys, there is evidence of increased availability of ETPs in HF in Europe, although too...

  5. 电力电缆局部放电的高频与特高频联合检测%Partial discharge combination detection with HF and UHF method for power cables

    Institute of Scientific and Technical Information of China (English)

    陈庆国; 蒲金雨; 丁继媛; 李昊; 孙建涛; 张书琦

    2013-01-01

    In order to carry out an on-line partial discharge detection for the after-laying power cables and suppress interference occurring in the on-site measurement, the combination method with HF(High Fre quency) and UHF (Ultra Frequency) measurement is proposed, and the on-line partial discharge detec tion system for power cables is established. The system consists of HF and UHF sensor, signal condition ing units, date-acquisition units and PC software, and the impulse interference was removed through mu tual identification between the HF and UHF signal. Meanwhile the interference suppression algorithm of multi-cycle superimposition based on complex wavelet was put forward. The test results for defect cable show that the system can effectively detect the HF and UHF signals of partial discharge with the sensitivity lower than 10 pc, and the processing results for measured data show that the proposed method can sup press the interference well.%为了对已敷设的电力电缆进行局部放电在线检测,并抑制现场测量时的干扰,采用高频(HF)与特高频(UHF)联合检测的方法,建立一套局部放电在线检测系统.该系统主要由HF和UHF传感器、信号调理单元、数据采集系统和上位机软件组成,通过HF信号和UHF信号的相互鉴别来去除脉冲型干扰信号.同时根据干扰信号和局部放电信号在频带及工频相位上的分布特点,提出基于复小波的多周期叠加干扰抑制算法.对缺陷电缆的试验结果表明,该系统能有效检测到局部放电的HF信号和UHF信号,局部放电检测灵敏度小于10 pc;对局部放电采集数据的处理结果表明,所提出的干扰抑制策略可很好地消除测量时的干扰信号.

  6. Systematic Study on Triaxial Superdeformed Bands of Hf Isotopes

    Institute of Scientific and Technical Information of China (English)

    ZHANG Da-Li; DING Bin-Gang

    2009-01-01

    Properties of the triaxial superdeformed (TSD) bands of Hf isotopes are investigated systematically within the supersymmetry scheme including many-body interactions and a perturbation possessing the SO(5) (or SU(5)) symmetry on the rotational symmetry. Quantitatively good results of the γ-ray energies, the dynamical moments of inertia,and the spin of the TSD bands in Hf isotopes are obtained. It shows that this approach is quite powerful in describing the properties of the triaxial superdeformation in Hf isotopes.

  7. 一种数字化TIG电源高频变压器设计方法%A design method of HF transformer for digital TIG welding power supply

    Institute of Scientific and Technical Information of China (English)

    刘强; 宋永伦

    2012-01-01

    随着电源需求的数字化、绿色化、高效化和多样化,高频逆变电源因其具有高效、节能、易控的特点成为新型电源的首选.高频变压器作为逆变电源的核心器件,其性能直接影响到电源的品质.根据高频变压器的工作原理,采用Ae*Le作为主要控制参数综合AP法,详细论述了设计方法和设计步骤,最后针对TIG电源的需求特点,通过实例化设计,对设计方法进行验证.%As the power supply requirements of the green, efficient and diversfication.high frequency inverter power supply comes to be the fust choice for new power supply because of its advantage in high efficiency,energy-saving and easy to control.High-frequency transformer is the core device of an inverter power supply.its performance directly affects the quality of the power supply.A design method for digital HF TIC power transformer is put forward and detailed design steps are analysed in this paper.

  8. Frederiksberg HF kursus

    DEFF Research Database (Denmark)

    Lindstrøm, Maria Duclos

    2008-01-01

    Notatet bygger på et interviewmateriale med dimitterede HF-kursister 3 måneder efter endt eksamen. Notatet undersøger dels, hvad der har hjulpet til at gennemføre, dels hvad der har været negativt og vanskeligt ved uddannelsen. Endvidere belyser notatet hvad kursisterne oplever at tage med fra de...

  9. Structure, optical properties and thermal stability of HfErO films deposited by simultaneous RF and VHF magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, H.Y. [Soochow University, College of Physics, Optoelectronics and Energy and Collaborative Innovation Center of Suzhou Nano Science and Technology, Suzhou (China); Nanjing University of Posts and Telecommunications, School of Tongda, Nanjing (China); Soochow University, Key Lab of Advanced Optical Manufacturing Technologies of Jiangsu Province and Key Lab of Modern Optical Technologies of Education Ministry of China, Suzhou (China); He, H.J.; Zhang, Z.; Jin, C.G.; Yang, Y.; Wang, Y.Y.; Ye, C. [Soochow University, College of Physics, Optoelectronics and Energy and Collaborative Innovation Center of Suzhou Nano Science and Technology, Suzhou (China); Soochow University, Key Lab of Advanced Optical Manufacturing Technologies of Jiangsu Province and Key Lab of Modern Optical Technologies of Education Ministry of China, Suzhou (China); Zhuge, L.J. [Soochow University, Key Lab of Advanced Optical Manufacturing Technologies of Jiangsu Province and Key Lab of Modern Optical Technologies of Education Ministry of China, Suzhou (China); Soochow University, Analysis and Testing Center, Suzhou (China); Wu, X.M. [Soochow University, College of Physics, Optoelectronics and Energy and Collaborative Innovation Center of Suzhou Nano Science and Technology, Suzhou (China); Soochow University, Key Lab of Advanced Optical Manufacturing Technologies of Jiangsu Province and Key Lab of Modern Optical Technologies of Education Ministry of China, Suzhou (China); Chinese Academy of Sciences, State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Shanghai (China)

    2015-01-23

    HfErO films are deposited on Si substrates by simultaneous radio frequency (RF) and very high frequency (VHF) magnetron sputtering technique. The content of the doped ingredient of Er and the body composition of HfO{sub x} are, respectively, controlled through the VHF and RF powers. Low content of Er doping in the HfErO films can be achieved, because the VHF source of 27.12 MHz has higher ion energy and lower ion flux than the RF source resulting in low sputtering rate in the magnetron sputtering system. The structure, optical properties and thermal stability of the HfErO films are investigated in this work. Results show that the doped content of Er is independently controlled by the VHF power. The oxygen vacancies are created by the Er incorporation. The hafnium in the HfErO films forms mixed valence of Hf{sup 2+} and Hf{sup 4+}. The HfErO films are composed with the structures of HfO{sub 2}, HfO and ErO{sub x}, which can be optimized through the VHF power. At high VHF power, the Hf-Er-O bonds are formed, which demonstrates that the Er atoms are doped into the lattice of HfO{sub 2} in the HfErO films. The HfErO films have bad thermal stability as the crystallization temperature decreases from 900 to 800 C. After thermal annealing, cubic phase of HfO{sub 2} are stabilized, which is ascribed to the oxygen vacancies creation by the Er incorporation. The optical properties such as the refractive index and the optical band gap of the HfErO films are optimized by the VHF power. (orig.)

  10. Percentage Energy from Fat Screener: Overview

    Science.gov (United States)

    A short assessment instrument to estimate an individual's usual intake of percentage energy from fat. The foods asked about on the instrument were selected because they were the most important predictors of variability in percentage energy.

  11. Solving Problems with the Percentage Bar

    Science.gov (United States)

    van Galen, Frans; van Eerde, Dolly

    2013-01-01

    At the end of primary school all children more of less know what a percentage is, but yet they often struggle with percentage problems. This article describes a study in which students of 13 and 14 years old were given a written test with percentage problems and a week later were interviewed about the way they solved some of these problems. In a…

  12. Low-Frequency Waves in HF Heating of the Ionosphere

    Science.gov (United States)

    Sharma, A. S.; Eliasson, B.; Milikh, G. M.; Najmi, A.; Papadopoulos, K.; Shao, X.; Vartanyan, A.

    2016-02-01

    Ionospheric heating experiments have enabled an exploration of the ionosphere as a large-scale natural laboratory for the study of many plasma processes. These experiments inject high-frequency (HF) radio waves using high-power transmitters and an array of ground- and space-based diagnostics. This chapter discusses the excitation and propagation of low-frequency waves in HF heating of the ionosphere. The theoretical aspects and the associated models and simulations, and the results from experiments, mostly from the HAARP facility, are presented together to provide a comprehensive interpretation of the relevant plasma processes. The chapter presents the plasma model of the ionosphere for describing the physical processes during HF heating, the numerical code, and the simulations of the excitation of low-frequency waves by HF heating. It then gives the simulations of the high-latitude ionosphere and mid-latitude ionosphere. The chapter also briefly discusses the role of kinetic processes associated with wave generation.

  13. New active load voltage clamp for HF-link converters

    Energy Technology Data Exchange (ETDEWEB)

    Ljusev, P.; Andersen, M.A.E.

    2005-07-01

    This paper proposes a new active clamp for HF-link converters, which features very high efficiency by returning the clamped energy back to the primary side through a small auxiliary converter. It also increases the reliability of HF-link converters by providing an alternative load current path during malfunctions of the secondary bidirectional bridge. The feasibility of the approach is shown on audio power amplifier prototype. New integrated magnetics design is presented that incorporates both the main power and auxiliary transformer on the same magnetic core. (au)

  14. New active load voltage clamp for HF-link converters

    DEFF Research Database (Denmark)

    Ljusev, Petar; Andersen, Michael Andreas E.

    2005-01-01

    This paper proposes a new active clamp for HF-link converters, which features very high efficiency by returning the clamped energy back to the primary side through a small auxiliary converter. It also increases the reliability of HF-link converters by providing an alternative load current path du...... during malfunctions of the secondary bidirectional bridge. The feasibility of the approach is shown on audio power amplifier prototype. New integrated magnetics design is presented that incorporates both the main power and auxiliary transformer on the same magnetic core....

  15. Mechanical properties of cast Ti-Hf alloys.

    Science.gov (United States)

    Sato, Hideki; Kikuchi, Masafumi; Komatsu, Masashi; Okuno, Osamu; Okabe, Toru

    2005-02-15

    This study examined the mechanical properties of a series of Ti-Hf alloys. Titanium alloys with 10 to 40 mass % Hf were made with titanium and hafnium sponge in an argon-arc melting furnace. Specimens cast into magnesia-based investment molds were tested for yield strength, tensile strength, percentage elongation, and modulus of elasticity. Vickers microhardness was determined at 25 to 600 microm from the cast surface. X-ray diffractometry was also performed. Commercially pure Ti (CP Ti) and pure Ti prepared from titanium sponge were used as controls. The data (n = 5) were analyzed with a one-way ANOVA and the Student-Newman-Keuls test (alpha = 0.05). The diffraction peaks of all the metals matched those for alpha Ti; no beta phase peaks were found. Alloys with Hf > or = 25% had significantly (p 0.05) in elongation among all the Ti-Hf alloys and CP Ti, whereas the elongation of alloys with Hf > or = 30% was significantly (p alloys tested can be considered viable alternatives to CP Ti because they were stronger than CP Ti and had similar elongation.

  16. Marburg Hemorrhagic Fever (Marburg HF)

    Science.gov (United States)

    ... CDC Cancel Submit Search The CDC Marburg hemorrhagic fever (Marburg HF) Note: Javascript is disabled or is ... first recognized in 1967, when outbreaks of hemorrhagic fever occurred simultaneously in laboratories in Marburg and Frankfurt, ...

  17. Hf Transition Probabilities and Abundances

    CERN Document Server

    Lawler, J E; Labby, Z E; Sneden, C; Cowan, J J; Ivans, I I

    2006-01-01

    Radiative lifetimes from laser-induced fluorescence measurements, accurate to about +/- 5 percent, are reported for 41 odd-parity levels of Hf II. The lifetimes are combined with branching fractions measured using Fourier transform spectrometry to determine transition probabilities for 150 lines of Hf II. Approximately half of these new transition probabilities overlap with recent independent measurements using a similar approach. The two sets of measurements are found to be in good agreement for measurements in common. Our new laboratory data are applied to refine the hafnium photospheric solar abundance and to determine hafnium abundances in 10 metal-poor giant stars with enhanced r-process abundances. For the Sun we derive log epsilon (Hf) = 0.88 +/- 0.08 from four lines; the uncertainty is dominated by the weakness of the lines and their blending by other spectral features. Within the uncertainties of our analysis, the r-process-rich stars possess constant Hf/La and Hf/Eu abundance ratios, log epsilon (Hf...

  18. 38 CFR 1.703 - Percentage estimate.

    Science.gov (United States)

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2010-07-01 2010-07-01 false Percentage estimate. 1.703 Section 1.703 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS GENERAL PROVISIONS Use of Official Mail in the Location and Recovery of Missing Children § 1.703 Percentage...

  19. Making Sense of Fractions and Percentages

    Science.gov (United States)

    Whitin, David J.; Whitin, Phyllis

    2012-01-01

    Because fractions and percentages can be difficult for children to grasp, connecting them whenever possible is beneficial. Linking them can foster representational fluency as children simultaneously see the part-whole relationship expressed numerically (as a fraction and as a percentage) and visually (as a pie chart). NCTM advocates these…

  20. Telemonitoring Adherence to Medications in Heart Failure Patients (TEAM-HF): A Pilot Randomized Clinical Trial.

    Science.gov (United States)

    Gallagher, Benjamin D; Moise, Nathalie; Haerizadeh, Mytra; Ye, Siqin; Medina, Vivian; Kronish, Ian M

    2017-04-01

    Medication nonadherence contributes to hospitalizations in recently discharged patients with heart failure (HF). We aimed to test the feasibility of telemonitoring medication adherence in patients with HF. We randomized 40 patients (1:1) hospitalized for HF to 30 days of loop diuretic adherence monitoring with telephonic support or to passive adherence monitoring alone. Eighty-three percent of eligible patients agreed to participate. The median age of patients was 64 years, 25% were female, and 45% were Hispanic. Overall, 67% of patients were nonadherent (percentage of days that the correct number of doses were taken telemonitoring was acceptable to most patients with HF. Diuretic nonadherence was common even when patients knew they were being monitored. Future studies should assess whether adherence telemonitoring can improve adherence and reduce readmissions among patients with HF. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Effe cts of diazepam on the percentage ofδ-band power of quantitative pharmaco-leectroenceph alogram in rabbits%地西泮对兔定量药物脑电图δ频段功率百分比的影响

    Institute of Scientific and Technical Information of China (English)

    王卿; 戴体俊

    2014-01-01

    目的:观察地西泮对兔定量药物脑电图(QPEEG)δ频段功率百分比的影响。方法24只成年家兔随机分为4组(n=6):分别静脉注射1 ml·kg -1生理盐水(NS组)及0.125、0.25、0.5 mg· kg -1地西泮(LD、MD、HD组),应用数字脑电地形图仪,计算给药前及给药后各时间点兔各脑区QPEEG δ频段功率百分比。结果与给药前比较,NS组、LD组各脑区δ频段功率百分比无明显变化(P>0.05),MD组和HD组各脑区δ频段功率百分比在30 s~30 min内显著增加(P<0.05或P<0.01),且与地西泮剂量呈正相关(r=0.564~0.943,P<0.01)。结论地西泮剂量依赖性增加兔各脑区δ频段功率百分比,提示δ频段可能成为反映镇静催眠程度的指标。%Objective To observe the effects of diazepam on the percentage of δ-band power of quantitative phar-maco-electroencephalogram (QPEEG) in rabbits.Methods Twenty-four adult rabbits were randomly divided into 4 groups (n=6), according to their intravenous injection of 1 mlk/g normal saline, 0.125, 0.25 and 0.5 mg/kg of diaze-pam.Then a digital EEG system was adopted to record the changes of QPEEG in eight encephalic regions 30 seconds be-fore and 30 seconds, 1, 2, 3, 5, 10, 15, 20, 25, 30 minutes after injection.Results Compared with the baseline, there was no remarkable change in the normal saline group and 0.125 mg/kg diazepam group as to the percentage of δ-band power.The percentage of δ-band power in the eight encephalic regions of 0.25 and 0.5 mg/kg diazepam groups were remarkably increased from 30 seconds to 30 minuts(P<0.05 or P<0.01).The change of the percentage of δ-band power was positively correlated with the dose of diazepam (r=0.564~0.943, P<0.01).Conclusion Diazepam treatment can increase the percentage of δ-band power of rabbit QPEEG in a dose -dependent way , indicating the po-tential role that δ-band power takes to assess the degree of sedation

  2. INTEGER PERCENTAGES AS ELECTORAL FALSIFICATION FINGERPRINTS

    NARCIS (Netherlands)

    Kobak, Dmitry; Shpilkin, Sergey; Pshenichnikov, Maxim S.

    2016-01-01

    We hypothesize that if election results are manipulated or forged, then, due to the well-known human attraction to round numbers, the frequency of reported round percentages can be increased. To test this hypothesis, we analyzed raw data from seven federal elections held in the Russian Federation du

  3. Effects of diazepam on the percentage of δ -band power of quantitative pharmaco-electroencephalogram in rabbits%地西泮与氟马西尼合用对兔定量药物脑电图δ频段功率百分比的影响

    Institute of Scientific and Technical Information of China (English)

    王卿; 赵健; 李玲玲; 戴体俊

    2015-01-01

    目的:观察地西泮对兔定量药物脑电图(QPEEG)δ频段功率百分比的影响及其与苯二氮�受体的关系。方法36只家兔随机分为6组(n=6),均静脉注射。空白组用0.9%氯化钠1 mL· kg-1,3个剂量地西泮组:0.12,0.25,0.50 mg· kg-1地西泮,氟马西尼组用氟马西尼0.1 mg· kg-1,合用组先注射0.1 mg· kg-1氟马西尼5 min后,再注射0.5 mg· kg-1地西泮。用数字脑电地形图仪分别计算给药前及给药后各时间点兔各脑区 QPEEGδ频段功率百分比。结果与给药前比较,0.25,0.50 mg· kg-1地西泮组各脑区δ频段功率百分比在0.5~30.0 min增加,且与地西泮剂量呈正相关;合用组的δ频段功率百分比明显低于同时点的0.50 mg· kg-1地西泮组。结论地西泮以剂量依赖方式增加兔QPEEGδ频段功率百分比且由苯二氮�受体介导,提示δ频段可能成为反映镇静催眠程度的指标。%Objective To observe the effects of diazepam on the percen-tage of δ -band power of quantitative pharmaco -electroencephalogram ( QPEEG ) in rabbits and the relation with benzodiazepine receptor.Methods Thirty-six healthy rabbits were randomly divided into 6 groups (each n=6),where rabbits in each group were intravenously injected with 1 mL· kg-1 0.9%NaCl (blank group), 0.12 mg· kg-1 , 0.25 mg· kg-1 or 0.50 mg· kg-1 diazepam groups, 0.1 mg· kg-1 flumazenil group and 0.1 mg· kg-1 flumazenil +0.5 mg· kg-1 diazepam ( combined group ).Then a digital EEG system was adopted to record the changes of QPEEG in eight encepha-lic regions before and after injection at each time point.Results The per-centage of δband power in eight encephalic regions of 0.25, 0.50 mg· kg-1 diazepam groups are noted increase within 0.5 to 30 min.The change of the percentage of δ band power has a positive correlation with diazepam dose.Compared with the 0.5 mg· kg-1 diazepam group,the percentage of δ-band power in combined

  4. First 100 ms of HF modification at Tromso, Norway

    Science.gov (United States)

    Djuth, F. T.; Isham, B.; Rietveld, M. T.; Hagfors, T.; La Hoz, C.

    Experiments were performed with the high-power high-frequency HF facility at Troms o Norway to test theoretical predictions for the excitation of ion and Langmuir oscillations in the ionosphere The principal diagnostic of wave-plasma interactions was the VHF radar at the European Incoherent Scatter EISCAT facility High resolution radar techniques were used to monitor the temporal development of the ion and Langmuir oscillations HF pulses 100 ms in duration were periodically transmitted into a smooth background F region plasma Measurements of the radar backscatter spectra show that all key spectral features predicted by strong Langmuir turbulence SLT theory modified Zakharov model are simultaneously present in the plasma and that their evolution is in agreement with theoretical expectations However several new features have been observed that cannot be anticipated by current theory because of limitations in the electric field strength within the simulations The experimental results reinforce the notion that new theoretical developments are needed to accommodate the large HF electric fields produced at Troms o and HAARP Gakona Alaska and to treat the electron acceleration process in a self-consistent fashion The F region response to two HF effective radiated power levels sim 58 MW and sim 125 MW was investigated at Troms o These ERP values include absorptive losses resulting from the sunlit D region In general the results at 58 MW ERP and 125 MW ERP are consistent with many of the SLT

  5. The Language of Comparisons: Communicating about Percentages

    Directory of Open Access Journals (Sweden)

    Jessica Polito

    2014-01-01

    Full Text Available While comparisons between percentages or rates appear frequently in journalism and advertising, and are an essential component of quantitative writing, many students fail to understand precisely what percentages mean, and lack fluency with the language used for comparisons. After reviewing evidence demonstrating this weakness, this experience-based perspective lays out a framework for teaching the language of comparisons in a structured way, and illustrates it with several authentic examples that exemplify mistaken or misleading uses of such numbers. The framework includes three common types of erroneous or misleading quantitative writing: the missing comparison, where a key number is omitted; the apples-to-pineapples comparison, where two subtly incomparable rates are presented; and the implied fallacy, where an invalid quantitative conclusion is left to the reader to infer.

  6. Environmentally friendly HF (DF) lasers

    Science.gov (United States)

    Apollonov, V. V.

    2016-08-01

    Dedicated to the 100th anniversary of the birth of Academician A M Prokhorov, this paper reviews the physics of self-sustained volume discharge without preionization—self-initiated volume discharge (SIVD)—in the working mixtures of non-chain hydrofluoride HF (deuterofluoride (DF)) lasers. The dynamics of SIVD in discharge gaps with different geometries is thoroughly described. The mechanisms for the restriction of current density in a diffuse channel in electric discharges in SF6 and SF6 based mixtures (which determines whether SIVD is possible) are proposed and analyzed using simple models. The most probable mechanisms are the electron impact dissociation of SF6 and other mixture components, electron-ion recombination and electron attachment to vibrationally excited SF6 molecules. Starting from a comparative analysis of the rate coefficients of these processes, it is shown that electron-ion recombination is capable of compensating for electron detachment from negative ions via electron impact. It is also established that SIVD is not only observed in SF6, but also in other strongly electronegative gases. The factors that determine the uniformity of the active medium in non-chain HF (DF) lasers are analyzed. Some special features of non-chain HF (DF) lasers with different apertures operating are carefully examined. Consideration is given to the problem of increasing the aperture and discharge volume of non-chain HF (DF) lasers. Based on our experimental results, the possibility of increasing the energy of such lasers to ~1 kJ and above is shown.

  7. Atomic scale engineering of HfO{sub 2}-based dielectrics for future DRAM applications

    Energy Technology Data Exchange (ETDEWEB)

    Dudek, Piotr

    2011-02-14

    Modern dielectrics in combination with appropriate metal electrodes have a great potential to solve many difficulties associated with continuing miniaturization process in the microelectronic industry. One significant branch of microelectronics incorporates dynamic random access memory (DRAM) market. The DRAM devices scaled for over 35 years starting from 4 kb density to several Gb nowadays. The scaling process led to the dielectric material thickness reduction, resulting in higher leakage current density, and as a consequence higher power consumption. As a possible solution for this problem, alternative dielectric materials with improved electrical and material science parameters were intensively studied by many research groups. The higher dielectric constant allows the use of physically thicker layers with high capacitance but strongly reduced leakage current density. This work focused on deposition and characterization of thin insulating layers. The material engineering process was based on Si cleanroom compatible HfO{sub 2} thin films deposited on TiN metal electrodes. A combined materials science and dielectric characterization study showed that Ba-added HfO{sub 2} (BaHfO{sub 3}) films and Ti-added BaHfO{sub 3} (BaHf{sub 0.5}Ti{sub 0.5}O{sub 3}) layers are promising candidates for future generation of state-of-the-art DRAMs. In especial a strong increase of the dielectric permittivity k was achieved for thin films of cubic BaHfO{sub 3} (k{proportional_to}38) and BaHf{sub 0.5}Ti{sub 0.5}O{sub 3} (k{proportional_to}90) with respect to monoclinic HfO{sub 2} (k{proportional_to}19). Meanwhile the CET values scaled down to 1 nm for BaHfO{sub 3} and {proportional_to}0.8 nm for BaHf{sub 0.5}Ti{sub 0.5}O{sub 3} with respect to HfO{sub 2} (CET=1.5 nm). The Hf{sup 4+} ions substitution in BaHfO{sub 3} by Ti{sup 4+} ions led to a significant decrease of thermal budget from 900 C for BaHfO{sub 3} to 700 C for BaHf{sub 0.5}Ti{sub 0.5}O{sub 3}. Future studies need to focus

  8. Uncertainties in pipeline water percentage measurement

    Energy Technology Data Exchange (ETDEWEB)

    Scott, Bentley N.

    2005-07-01

    Measurement of the quantity, density, average temperature and water percentage in petroleum pipelines has been an issue of prime importance. The methods of measurement have been investigated and have seen continued improvement over the years. Questions are being asked as to the reliability of the measurement of water in the oil through sampling systems originally designed and tested for a narrow range of densities. Today most facilities sampling systems handle vastly increased ranges of density and types of crude oils. Issues of pipeline integrity, product loss and production balances are placing further demands on the issues of accurate measurement. Water percentage is one area that has not received the attention necessary to understand the many factors involved in making a reliable measurement. A previous paper1 discussed the issues of uncertainty of the measurement from a statistical perspective. This paper will outline many of the issues of where the errors lie in the manual and automatic methods in use today. A routine to use the data collected by the analyzers in the on line system for validation of the measurements will be described. (author) (tk)

  9. Uncertainties in pipeline water percentage measurement

    Energy Technology Data Exchange (ETDEWEB)

    Scott, Bentley N.

    2005-07-01

    Measurement of the quantity, density, average temperature and water percentage in petroleum pipelines has been an issue of prime importance. The methods of measurement have been investigated and have seen continued improvement over the years. Questions are being asked as to the reliability of the measurement of water in the oil through sampling systems originally designed and tested for a narrow range of densities. Today most facilities sampling systems handle vastly increased ranges of density and types of crude oils. Issues of pipeline integrity, product loss and production balances are placing further demands on the issues of accurate measurement. Water percentage is one area that has not received the attention necessary to understand the many factors involved in making a reliable measurement. A previous paper1 discussed the issues of uncertainty of the measurement from a statistical perspective. This paper will outline many of the issues of where the errors lie in the manual and automatic methods in use today. A routine to use the data collected by the analyzers in the on line system for validation of the measurements will be described. (author) (tk)

  10. Ferroelectric modulation of terahertz waves with graphene/ultrathin-Si:HfO2/Si structures

    Science.gov (United States)

    Jiang, Ran; Han, Zuyin; Sun, Weideng; Du, Xianghao; Wu, Zhengran; Jung, Hyung-Suk

    2015-10-01

    Ferroelectric-field-effect-tunable modulation of terahertz waves in graphene/Si:HfO2/Si stack structure was observed. The modulation shows distinct behaviors when the samples under different gate polarities. At a negative voltage, a transmission modulation depth up to ˜74% was present without depending on the photo illumination power, whereas, at a positive voltage, the modulation of Thz wave shows dependence on the illumination power, which is ascribed to the creation/elimination of an extra barrier in Si layer in response to the polarization in the ferroelectric Si:HfO2 layer. Considering the good compatibility of HfO2 on Si-based semiconductor process, the ferroelectricity layer of Si:HfO2 may open up an avenue for the tunable modulation of Thz wave.

  11. A thirty second isomer in Hf-171

    NARCIS (Netherlands)

    Campbell, P; Billowes, J; Cochrane, ECA; Cooke, JL; Cooper, TG; Dendooven, P; Evans, DE; Grant, IS; Griffith, JAR; Honkanen, A; Huhta, M; Oinonen, M; Pearson, MR; Penttila, H; Persson, B.L.; Richardson, DS; Tungate, G; Wheeler, PD; Zybert, L; Aysto, J

    1997-01-01

    An isomer has been detected in Hf-171 with a half-life of T-1/2 = 29.5(9) s. The state was populated in the Yb-170(alpha,3n)Hf-171m reaction at a beam energy of E-alpha = 50 MeV in an on-line ion guide isotope separator. The isomeric Hf-17lm(+) beam was extracted from the ion guide, mass-analysed an

  12. The Instagram: A Novel Sounding Technique for Enhanced HF Propagation Advice

    Science.gov (United States)

    2010-05-01

    The Instagram : A Novel Sounding Technique for Enhanced HF Propagation Advice Rod I. Barnes, G. Fred Earl Riverside Research Organization Rosslyn...low transmit powers, is reduced over conventional methods by up to three orders of magnitude leading to the term ‘ Instagram ’. The technique is...TYPE 3. DATES COVERED 00-00-2010 to 00-00-2010 4. TITLE AND SUBTITLE The Instagram : A Novel Sounding Technique for Enhanced HF Propagation Advice

  13. Characterization of Ionosphere Waveguide Propagation by Monitoring HAARP HF Transmissions in Antarctica

    Science.gov (United States)

    2015-04-17

    AFRL-AFOSR-UK-TR-2015-0024 CHARACTERIZATION OF IONOSPHERE WAVEGUIDE PROPAGATION BY MONITORING HAARP HF TRANSMISSIONS IN ANTARCTICA *Yuri M...31 December 2014 4. TITLE AND SUBTITLE CHARACTERIZATION OF IONOSPHERE WAVEGUIDE PROPAGATION BY MONITORING HAARP HF TRANSMISSIONS IN ANTARCTICA 5a...investigating the possibility of exciting the ionospheric interlayer duct channel using powerful radiation from the heaters HAARP (Alaska, USA) and EISCAT

  14. Artificial Ionization and UHF Radar Response Associated with HF Frequencies near Electron Gyro-Harmonics (Invited)

    Science.gov (United States)

    Watkins, B. J.; Fallen, C. T.; Secan, J. A.

    2013-12-01

    significantly increased and strong signals persist while the high-power HF is present . Simultaneous observations of topside TEC measurements and lower-ionosphere UHF radar observations suggest there is an optimum altitude region to heat the lower F-region in order to produce topside ionosphere density enhancements. The observations are dependent on HF power levels and we show several examples where heating results are only observed for the high-power levels attainable with the HAARP facility.

  15. Ionospheric heating with oblique HF waves

    Science.gov (United States)

    Field, Edward C., Jr.; Bloom, Ron M.

    1990-10-01

    Calculations of ionospheric electron density perturbations and ground-level signal changes produce by intense oblique high frequency (HF) transmitters are presented. This analysis considers radio field focusing at caustics, the consequent joule-heating of the surrounding plasma, heat conduction, diffusion, and recombination processes: these being the effects of a powerful oblique 'modifying' wave. It neglects whatever plasma instabilities might occur. Then effects on a secondary 'test' wave that is propagated along the same path as the first are investigated. Calculations predict ground-level field-strength reductions of several dB in the test wave for modifying waves having ERP in the 85 to 90 dBW range. These field-strength changes are similar in sign, magnitude, and location to ones measured in Soviet experiments. The results are sensitive to the model ionosphere assumed, so future experiments should employ the widest possible range of frequencies and propagation conditions. An effective power of 90 dBW seems to be a sort of threshold that, if exceeded, results in substantial rather than small signal changes. The conclusions are based solely on joule-heating and subsequent defocusing of waves passing through caustic regions.

  16. The study of multilayers Fe/Hf and Ni/Hf by slow positron beam technique

    Science.gov (United States)

    Tashiro, Mutsumi; Nakajyo, Terunobu; Murashige, Yusuke; Koizumi, Tomoya; Kanazawa, Ikuzo; Komori, Fumio; Soe, We-Hyo; Yamamoto, Ryoichi; Ito, Yasuo

    1997-05-01

    The S-parameters versus the incident positron energy are measured in the Ni/Hf multilayer, thin Hf film, thin Fe film and the bilayer Fe/Hf. We have analyzed the change in vacancy-type defects in these multilayers and thin films with the deposition temperature in the MBE system.

  17. HfS, Hyperfine Structure Fitting Tool

    CERN Document Server

    Estalella, Robert

    2016-01-01

    HfS is a tool to fit the hyperfine structure of spectral lines, with multiple velocity components. The HfS_nh3 procedures included in HfS fit simultaneously the hyperfine structure of the NH$_3$ (J,K)= (1,1) and (2,2) transitions, and perform a standard analysis to derive $T_\\mathrm{ex}$, NH$_3$ column density, $T_\\mathrm{rot}$, and $T_\\mathrm{k}$. HfS uses a Monte Carlo approach for fitting the line parameters. Especial attention is paid to the derivation of the parameter uncertainties. HfS includes procedures that make use of parallel computing for fitting spectra from a data cube.

  18. Experimental and numerical investigation of the refinement of Hf by EBM

    Science.gov (United States)

    Donchev, Veliko; Vutova, Katia; Vassileva, Vania

    2014-05-01

    Electron beam melting (EBM) in vacuum is one of the most promising technologies for refining and recycling of metals that react with oxygen when heated. Hf is such a metal. Pure Hf (with a small content of gas and metal impurities) is needed for a variety of applications in the aerospace industry and metallurgy, in the production of components of nuclear reactors, microprocessors, optical components etc. We conducted experiments with the ELIT-60 equipment on Hf ingots at electron beam powers of 12, 15, 17 kW and obtained data about the concentration of impurities by the ICP-MS method. For further understanding and optimizing the Hf refining processes, a non-stationary heat model was applied for numerical simulation of the heat transfer processes. Simulation data about the liquid pool variation during the e-beam treatment was thus obtained. The flatness of the crystallization front shape, which is connected to the structure quality, was investigated by optimization criteria related to the curvature of the liquid/solid boundary curve. We also describe an algorithm for calculation of the criteria. One of the criteria was applied to EBM of Hf for different electron beam powers; the results obtained were confirmed by the experimental data. Combining experimental, theoretical and simulation results, a proper technological regime is proposed for better Hf refining.

  19. Finland HF and Esrange MST radar observations of polar mesosphere summer echoes

    Directory of Open Access Journals (Sweden)

    T. Ogawa

    Full Text Available Peculiar near range echoes observed in summer with the SuperDARN HF radar in Finland are presented. The echoes were detected at four frequencies of 9, 11, 13 and 15 MHz at slant ranges of 105–250 km for about 100 min. Interferometer measurements indicate that the echoes are returned from 80–100 km altitudes with elevation angles of 20°–60°. Echo power (< 16 dB, Doppler velocity (between –30 and + 30 ms-1 and spectral width (< 60 ms-1 fluctuate with periods of several to 20 min, perhaps due to short–period atmospheric gravity waves. When the HF radar detected the echoes, a vertical incidence MST radar, located at Esrange in Sweden (650 km north of the HF radar site, observed polar mesosphere summer echoes (PMSE at altitudes of 80–90 km. This fact suggests that the near range HF echoes are PMSE at HF band, although both radars did not probe a common volume. With increasing radar frequency, HF echo ranges are closer to the radar site and echo power becomes weaker. Possible mechanisms to explain these features are discussed.

    Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; thermospheric dynamics; waves and tides; instruments and techniques

  20. Modulation of auroral electrojet currents using dual HF beams with ELF phase offset

    Science.gov (United States)

    Golkowski, M.; Cohen, M.; Moore, R. C.

    2012-12-01

    The modulation of naturally occuring ionospheric currents with high power radio waves in the high frequency (HF, 3-10 MHz) band is a well known technique for generation of extremely low frequency (ELF, 3-3000 Hz) and very low frequency (VLF, 3-30 kHz) waves. We use the heating facility of the High Frequency Active Auroral Research Program (HAARP) to investigate the effect of using dual HF beams with an ELF/VLF phase offset between the modulation waveforms. Experiments with offset HF beams confirm the model of independent ELF/VLF sources. Experiments with co-located HF beams exhibit interaction between the first and second harmonics of the modulated tones when square and sine wave modulation waveforms are employed. Using ELF/VLF phase offsets for co-loacted beams is also shown to be a potential diagnostic for the D-region ionospheric profile.

  1. Aspects of HF radio propagation

    Directory of Open Access Journals (Sweden)

    Stephane Saillant

    2009-06-01

    Full Text Available

    radio systems. From the point of view Working Group 2 of the COST 296 Action, interest lies with effects associated

    with propagation via the ionosphere of signals within the HF band. Several aspects are covered in this paper:

    a The directions of arrival and times of flight of signals received over a path oriented along the trough have

    been examined and several types of propagation effects identified. Of particular note, combining the HF observations

    with satellite measurements has identified the presence of irregularities within the floor of the trough that

    result in propagation displaced from the great circle direction. An understanding of the propagation effects that

    result in deviations of the signal path from the great circle direction are of particular relevance to the operation

    of HF radiolocation systems.

    b Inclusion of the results from the above mentioned measurements into a propagation model of the northerly

    ionosphere (i.e. those regions of the ionosphere located poleward of, and including, the mid-latitude trough

    and the use of this model to predict the coverage expected from transmitters where the signals impinge on the

    northerly ionosphere

  2. Power

    DEFF Research Database (Denmark)

    Elmholdt, Claus Westergård; Fogsgaard, Morten

    2016-01-01

    In this chapter, we will explore the dynamics of power in processes of creativity, and show its paradoxical nature as both a bridge and a barrier to creativity in organisations. Recent social psychological experimental research (Slighte, de Dreu & Nijstad, 2011) on the relation between power...... and creativity suggests that when managers give people the opportunity to gain power and explicate that there is reason to be more creative, people will show a boost in creative behaviour. Moreover, this process works best in unstable power hierarchies, which implies that power is treated as a negotiable...... and floating source for empowering people in the organisation. We will explore and discuss here the potentials, challenges and pitfalls of power in relation to creativity in the life of organisations today. The aim is to demonstrate that power struggles may be utilised as constructive sources of creativity...

  3. Effect of HF Heating Array Directivity Pattern on the Frequency Response of Generated ELF/VLF.

    Science.gov (United States)

    1983-01-01

    hhEEE|hhEE 1H ; 11:j28 111125 . mm 11111 II ll1 111 .8 MICROCOPY RESOLUTION TESI CHART I fJC ’RL_-SCI-475l I( .-cmon Numters: 1.5.1. 3.1.4, 3.2.1,.3.3...the high power HF heating facility at the Arecibo Observatory in Puerto Rico. The pattern was calculated using pattern multi- plication and method of...high power HF heating facility at the Arecibo Observatory in Puerto Rico. The pattern was calculated using pattern multiplication and method of

  4. Height dependence of the observed spectrum of radar backscatter from HF-induced ionospheric Langmuir turbulence

    Science.gov (United States)

    Fejer, J. A.; Sulzer, M. P.; Djuth, F. T.

    1991-09-01

    Results are presented of observations of the spectrum of the 430-MHz radar backscatter from HF-induced Langmuir turbulence with height discrimination. During very stable ionospheric conditions under which the height of the below-threshold backscatter spectrum changed by less than 300 m during a 7-min period, a 20-s-long temporary increase in the HF power from 3 MW ERP to 38-MW-equivalent-radiated HF power is found to result in subsequent strong above-threshold spectra extending to heights up to 1200 m greater than the height of the below-threshold spectrum for more than a minute. The generation of irregularities in the plasma density during the 20 s of enhanced HF power is suggested as a possible cause of this persistence of strong above-threshold spectra at greater heights. The initial temporal evolution of the backscatter spectrum from Langmuir turbulence after the start of HF transmissions is observed for different heights. The observational results are compared with the predictions of existing theories of Langmuir turbulence.

  5. HF Transverse Segmentation and Tagging Jet Capability

    CERN Document Server

    Doroshkevich, E A; Kuleshov, Sergey

    1998-01-01

    So called tagging jets and pile-up were simulated for the optimisation of the HF segmentation. The energy resolution, angular resolution and efficiency of jet reconstruction are defined for different calorimeter segmentation.

  6. Collisional quenching of highly rotationally excited HF

    CERN Document Server

    Yang, Benhui; Forrey, R C; Stancil, P C; Balakrishnan, N

    2015-01-01

    Collisional excitation rate coefficients play an important role in the dynamics of energy transfer in the interstellar medium. In particular, accurate rotational excitation rates are needed to interpret microwave and infrared observations of the interstellar gas for nonlocal thermodynamic equilibrium line formation. Theoretical cross sections and rate coefficients for collisional deexcitation of rotationally excited HF in the vibrational ground state are reported. The quantum-mechanical close-coupling approach implemented in the nonreactive scattering code MOLSCAT was applied in the cross section and rate coefficient calculations on an accurate 2D HF-He potential energy surface. Estimates of rate coefficients for H and H$_2$ colliders were obtained from the HF-He collisional data with a reduced-potential scaling approach. The calculation of state-to-state rotational quenching cross sections for HF due to He with initial rotational levels up to $j=20$ were performed for kinetic energies from 10$^{-5}$ to 15000...

  7. Microhardness evaluation alloys Hf-Si-B; Avaliacao de microdureza de ligas Hf-Si-B

    Energy Technology Data Exchange (ETDEWEB)

    Gigolotti, Joao Carlos Janio; Costa, Eliane Fernandes Brasil [Centro Universitario de Volta Redonda (UNIFOA), Volta Redonda, RJ (Brazil); Nunes, Carlos Angelo; Rocha, Elisa Gombio; Coelho, Gilberto Carvalho, E-mail: carlosjanio@uol.com.br, E-mail: eliane-costabrasi@hotmail.com, E-mail: cnunes@demar.eel.usp.br, E-mail: elisarocha@alunos.eel.usp.br, E-mail: coelho@demar.eel.usp.br [Universidade de Sao Paulo (USP), Lorena, SP (Brazil)

    2014-08-15

    The technological advance has generated increasing demand for materials that can be used under high temperature, what includes intermetallic MR-Si-B (MR = refractory metal) alloys with multiphase structures, that can also be applied in oxide environments. Thus, this work had for objective the micro hardness study of the Hf-Si-B system alloys, heat treated at 1600 deg C, in the Hf rich region. Hf-Si-B alloys had been produced with blades of Hf (min. 99.8%), Si (min. 99.998%) and B (min. 99.5%), in the voltaic arc furnace and heat treated at 1600 deg C under argon atmosphere. The relationship of the phases had been previously identified by X-ray diffraction and contrast in backscattered electron imaging mode. The alloys had their hardness analyzed by method Vickers (micro hardness) with load of 0.05 kgf and 0.2 kgf and application time of 20 s. The results, obtained from the arithmetic mean of measurements for each alloy on the heterogeneous region, showed a mean hardness of 11.08 GPA, with small coefficient of variation of 3.8%. The borides HfB2 (19.34 GPa) e HfB - 11.76 GPa, showed the hardness higher than the silicides Hf2Si (8.57 GPa), Hf5Si3 (9.63 GPa), Hf3Si2 (11.66 GPa), Hf5Si4 (10.00 GPa), HfSi (10.02 GPa) e HfSi2 (8.61 GPa). (author)

  8. ELF/VLF wave generation from the beating of two HF ionospheric heating sources

    Science.gov (United States)

    Cohen, M. B.; Moore, R. C.; Golkowski, M.; Lehtinen, N. G.

    2012-12-01

    It is well established that Extremely Low Frequency (ELF, 0.3-3 kHz) and Very Low Frequency (VLF, 3-30 kHz) radio waves can be generated via modulated High Frequency (HF, 3-10 MHz) heating of the lower ionosphere (60-100 km). The ionospheric absorption of HF power modifies the conductivity of the lower ionosphere, which in the presence of natural currents such as the auroral electrojet, creates an `antenna in the sky.' We utilize a theoretical model of the HF to ELF/VLF conversion and the ELF/VLF propagation, and calculate the amplitudes of the generated ELF/VLF waves when two HF heating waves, separated by the ELF/VLF frequency, are transmitted from two adjacent locations. The resulting ELF/VLF radiation pattern exhibits a strong directional dependence (as much as 15 dB) that depends on the physical spacing of the two HF sources. This beat wave source can produce signals 10-20 dB stronger than those generated using amplitude modulation, particularly for frequencies greater than 5-10 kHz. We evaluate recent suggestions that beating two HF waves generates ELF/VLF waves in the F-region (>150 km), and conclude that those experimental results may have misinterpreted, and can be explained strictly by the much more well established D region mechanism.

  9. HF beacon network for ionospheric specification in Peru

    Science.gov (United States)

    Hysell, D. L.; Milla, M. A.; Vierinen, J.

    2016-12-01

    A growing network of HF beacon transmitters and receivers is being deployed in Peru for specifying the F region ionosphere regionally. The effort is motivated by ionospheric disturbances associated with equatorial spread F (ESF), especially disturbances arising under inauspicious ESF conditions. The beacons use dual frequencies (2.72 and 3.64 MHz). They incorporate PRN coding to afford group-delay measurements. Scatered power, Doppler shift, bearing, and polarization are also measured. An algorithm for inverting the beacon data combined with electron density profiles from Jicamarca is described. Data and representative solutions from recent campaigns will be reviewed.

  10. 7 CFR 981.48 - Increase of salable percentage.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Increase of salable percentage. 981.48 Section 981.48... Regulating Handling Volume Regulation § 981.48 Increase of salable percentage. Upon request filed prior to... for the crop year, the Secretary may increase the salable percentage. Such findings shall be made in...

  11. 7 CFR 930.15 - Restricted percentage cherries.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Restricted percentage cherries. 930.15 Section 930.15... Agreements and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE TART CHERRIES GROWN IN THE STATES... Handling Definitions § 930.15 Restricted percentage cherries. Restricted percentage cherries means...

  12. About the scheme of the infrared FEL system for the accelerator based on HF wells

    Energy Technology Data Exchange (ETDEWEB)

    Kabanov, V.S.; Dzergach, A.I. [Moscow Radiotechnical Institute (Russian Federation)

    1995-12-31

    Accelerators, based on localization of plasmoids in the HF wells (RF traps) of the axially-symmetric electromagnetic field E {sub omn} in an oversized (m,n>>1) resonant system, can give accelerating gradients {approximately}100 kV/{lambda}, e.g. 10 GV/m if {lambda}=10 {mu}m. One of possible variants of HF feeding for these accelerators is based on using the powerful infrared FEL System with 2 frequencies. The corresponding FEL`s may be similar to the Los Alamos compact Advanced FEL ({lambda}{sub 1,2}{approximately}10 pm, e-beam energy {approximately}15 MeV, e-beam current {approximately}100 A). Their power is defined mainly by the HF losses in the resonant system of the supposed accelerator.

  13. Nightside studies of coherent HF Radar spectral width behaviour

    Directory of Open Access Journals (Sweden)

    E. E. Woodfield

    Full Text Available A previous case study found a relationship between high spectral width measured by the CUTLASS Finland HF radar and elevated electron temperatures observed by the EISCAT and ESR incoherent scatter radars in the post-midnight sector of magnetic local time. This paper expands that work by briefly re-examining that interval and looking in depth at two further case studies. In all three cases a region of high HF spectral width (>200 ms-1 exists poleward of a region of low HF spectral width (<200 ms-1. Each case, however, occurs under quite different geomagnetic conditions. The original case study occurred during an interval with no observed electrojet activity, the second study during a transition from quiet to active conditions with a clear band of ion frictional heating indicating the location of the flow reversal boundary, and the third during an isolated sub-storm. These case studies indicate that the relationship between elevated electron temperature and high HF radar spectral width appears on closed field lines after 03:00 magnetic local time (MLT on the nightside. It is not clear whether the same relationship would hold on open field lines, since our analysis of this relationship is restricted in latitude. We find two important properties of high spectral width data on the nightside. Firstly the high spectral width values occur on both open and closed field lines, and secondly that the power spectra which exhibit high widths are both single-peak and multiple-peak. In general the regions of high spectral width (>200 ms-1 have more multiple-peak spectra than the regions of low spectral widths whilst still maintaining a majority of single-peak spectra. We also find that the region of ion frictional heating is collocated with many multiple-peak HF spectra. Several mechanisms for the generation of high spectral width have been proposed which would produce multiple-peak spectra, these are discussed in relation to

  14. Tristatic EISCAT-UHF measurements of the HF modified ionosphere for low background electron temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Westman, A.; Leyser, T.B. [Swedish Institute of Space Physics, Kiruna (Sweden); Wannberg, G. [EISCAT Scientific Association, Kiruna (Sweden)] [and others

    1995-06-01

    The authors report measurements from one of the first tristatic EISCAT-UHF incoherent scatter experiments, where powerful HF beams were transmitted to the daytime F region. Scattered signals were monitored to study spectral structure and time dependence of the excited plasma. The observed plasma turbulence varied considerably, with conditions of low T{sub e} as starting conditions.

  15. AC Own Motion Percentage of Randomly Sampled Cases

    Data.gov (United States)

    Social Security Administration — Longitudinal report detailing the numbers and percentages of Appeals Council (AC) own motion review actions taken on un-appealed favorable hearing level decisions...

  16. General concepts of modern HF communications

    Science.gov (United States)

    Aarons, Jules

    Both conceptual and hardware advancements have led to substantial systems developments in military HF communications; the former encompass coding and error correction techniques for security, in order to minimize propagation and interference, while the latter prominently include digital equipment permitting the selection of a frequency for a particular path and propagation mode, as well as modulation selection. Propagation-related advancements involve better statistical models as well as advancements in short-term forecasting methods responsive to changes in solar-geophysical parameters. Adaptive HF systems have been developed for meteor-scatter radio communications.

  17. Research on Multi-Layer Distributed HF Radio Network Structure

    Institute of Scientific and Technical Information of China (English)

    Hui Dai; Chun-Jiang Wang; Quan Yu

    2008-01-01

    High frequency (HF) transmission is an important communication techniques. However, conventional point-to-point transmission can be easily destroyed, which limits its utilization in practice. HF networking communication has the capability against demolishment. The network structure is one of the key factors for HF networking communication. In this paper, a novel analysis method of the network connectedness based on the eigenvalue is derived, and a multi-layer distributed HF radio network structure is proposed. Both the theore tical analysis and the computer simulation results verify that the application of the proposed network structure in the HF radio communication can improve the anti demolishment ability of the HF network efficiently.

  18. 18 CFR 35.22 - Limits for percentage adders in rates for transmission services; revision of rate schedules...

    Science.gov (United States)

    2010-04-01

    ... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false Limits for percentage adders in rates for transmission services; revision of rate schedules, tariffs or service agreements. 35... Filing Requirements § 35.22 Limits for percentage adders in rates for transmission services; revision...

  19. Fabrication of resistive switching memory based on solution processed PMMA-HfO x blended thin films

    Science.gov (United States)

    Lee, Jae-Won; Cho, Won-Ju

    2017-02-01

    In this study, we developed PMMA-HfO x blended resistive random access memory (ReRAM) devices using solution processing to overcome the drawbacks of the individual organic and inorganic materials. Resistive switching behaviors of solution-processed PMMA, PMMA-HfO x , and HfO x film-based ReRAM devices were investigated. The poor electrical characteristic of PMMA and brittle mechanical properties of HfO x can be improved by blending PMMA and HfO x together. The PMMA-HfO x blended ReRAM device exhibited a larger memory window, stable endurance and retention, a lower operation power, and better set/reset voltage distributions. Furthermore, these new systems featured multilevel conduction states at different reset bias for non-volatile multilevel memory applications. Therefore, solution-processed PMMA-HfO x blended films are a promising material for non-volatile memory devices on flexible or wearable electronic systems.

  20. 7 CFR 201.61 - Fluorescence percentages in ryegrasses.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Fluorescence percentages in ryegrasses. 201.61 Section... ACT FEDERAL SEED ACT REGULATIONS Tolerances § 201.61 Fluorescence percentages in ryegrasses. Tolerances for 400-seed fluorescence tests shall be those set forth in the following table plus one-half...

  1. 78 FR 33757 - Rural Determination and Financing Percentage

    Science.gov (United States)

    2013-06-05

    ... finance where the project supplies electricity to an electric utility serving an area that is less than... funds to finance the construction and improvement of electric projects in rural areas, including... Percentage. It has been the Agency's practice to finance only that percentage of a project cost that equates...

  2. 15 CFR 23.4 - Cost and percentage estimates.

    Science.gov (United States)

    2010-01-01

    ... 15 Commerce and Foreign Trade 1 2010-01-01 2010-01-01 false Cost and percentage estimates. 23.4... LOCATION AND RECOVERY OF MISSING CHILDREN § 23.4 Cost and percentage estimates. It is estimated that this... estimate that 9% of its penalty mail will transmit missing children photographs and information when...

  3. 28 CFR 19.4 - Cost and percentage estimates.

    Science.gov (United States)

    2010-07-01

    ... 28 Judicial Administration 1 2010-07-01 2010-07-01 false Cost and percentage estimates. 19.4... RECOVERY OF MISSING CHILDREN § 19.4 Cost and percentage estimates. It is estimated that this program will cost DOJ $78,000 during the initial year. This figure is based on estimates of printing, inserting,...

  4. 7 CFR 930.8 - Free market tonnage percentage cherries.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Free market tonnage percentage cherries. 930.8 Section... CHERRIES GROWN IN THE STATES OF MICHIGAN, NEW YORK, PENNSYLVANIA, OREGON, UTAH, WASHINGTON, AND WISCONSIN Order Regulating Handling Definitions § 930.8 Free market tonnage percentage cherries. Free...

  5. Systematic Comparison of HF CMOS Transconductors

    NARCIS (Netherlands)

    Klumperink, Eric A.M.; Nauta, Bram

    2003-01-01

    Transconductors are commonly used as active elements in high-frequency (HF) filters, amplifiers, mixers, and oscillators. This paper reviews transconductor design by focusing on the V-I kernel that determines the key transconductor properties. Based on bandwidth considerations, simple V-I kernels wi

  6. Electron impact on vibrationally cold {{HF}}^{+}

    Science.gov (United States)

    Cristian Stroe, Marius; Fifirig, Magda

    2016-12-01

    The dissociative recombination and vibrational excitation processes induced by electron impact on vibrationally cold {{HF}}+ are investigated in the framework of the multichannel quantum defect theory for electron energies below 1 eV. The thermal rate coefficients for the electron temperature range from 10 to 5000 K are reported.

  7. ORIGIN OF EXCESS (176)Hf IN METEORITES

    DEFF Research Database (Denmark)

    Thrane, Kristine; Connelly, James Norman; Bizzarro, Martin

    2010-01-01

    After considerable controversy regarding the (176)Lu decay constant (lambda(176)Lu), there is now widespread agreement that (1.867 +/- 0.008) x 10(-11) yr(-1) as confirmed by various terrestrial objects and a 4557 Myr meteorite is correct. This leaves the (176)Hf excesses that are correlated with...

  8. Association between frequency of atrial and ventricular ectopic beats and biventricular pacing percentage and outcomes in patients with cardiac resynchronization therapy

    DEFF Research Database (Denmark)

    Ruwald, Martin H; Mittal, Suneet; Ruwald, Anne-Christine

    2014-01-01

    -defibrillator device with data available on biventricular pacing percentage and pre-implantation 24-h Holter recordings were included. Using logistic regression, we estimated the influence of ectopic beats on the percentage of biventricular pacing. Reverse remodeling was measured as reductions in atrial and left.......001) in patients with >1.5% ectopic beats compared with those with reverse remodeling (percent reduction in LVESV 31 ± 15%) than patients with ... biventricular pacing (reverse remodeling and higher risk of HF/death and VTA. This supports pre-implantation Holter monitoring of patients selected for CRT for optimal outcome. (MADIT-CRT: Multicenter Automatic Defibrillator Implantation With Cardiac Resynchronization...

  9. Observations of HF backscatter decay rates from HAARP generated FAI

    Science.gov (United States)

    Bristow, W. A.; Hysell, D. L.

    2016-12-01

    Suitable experiments at the High-frequency Active Auroral Research Program (HAARP) facilities in Gakona, Alaska, create a region of ionospheric Field-Aligned Irregularities (FAI) that produces strong radar backscatter observed by the SuperDARN radar on Kodiak Island, Alaska. Creation of FAI in HF ionospheric modification experiments has been studied by a number of authors who have developed a rich theoretical background. The decay of the irregularities, however, has not been so widely studied yet it has the potential for providing estimates of the parameters of natural irregularity diffusion, which are difficult measure by other means. Hysell, et al. [1996] demonstrated using the decay of radar scatter above the Sura heating facility to estimate irregularity diffusion. A large database of radar backscatter from HAARP generated FAI has been collected over the years. Experiments often cycled the heater power on and off in a way that allowed estimates of the FAI decay rate. The database has been examined to extract decay time estimates and diffusion rates over a range of ionospheric conditions. This presentation will summarize the database and the estimated diffusion rates, and will discuss the potential for targeted experiments for aeronomy measurements. Hysell, D. L., M. C. Kelley, Y. M. Yampolski, V. S. Beley, A. V. Koloskov, P. V. Ponomarenko, and O. F. Tyrnov, HF radar observations of decaying artificial field aligned irregularities, J. Geophys. Res. , 101, 26,981, 1996.

  10. Observations of HF backscatter decay rates from HAARP generated FAI

    Science.gov (United States)

    Bristow, William; Hysell, David

    2016-07-01

    Suitable experiments at the High-frequency Active Auroral Research Program (HAARP) facilities in Gakona, Alaska, create a region of ionospheric Field-Aligned Irregularities (FAI) that produces strong radar backscatter observed by the SuperDARN radar on Kodiak Island, Alaska. Creation of FAI in HF ionospheric modification experiments has been studied by a number of authors who have developed a rich theoretical background. The decay of the irregularities, however, has not been so widely studied yet it has the potential for providing estimates of the parameters of natural irregularity diffusion, which are difficult measure by other means. Hysell, et al. [1996] demonstrated using the decay of radar scatter above the Sura heating facility to estimate irregularity diffusion. A large database of radar backscatter from HAARP generated FAI has been collected over the years. Experiments often cycled the heater power on and off in a way that allowed estimates of the FAI decay rate. The database has been examined to extract decay time estimates and diffusion rates over a range of ionospheric conditions. This presentation will summarize the database and the estimated diffusion rates, and will discuss the potential for targeted experiments for aeronomy measurements. Hysell, D. L., M. C. Kelley, Y. M. Yampolski, V. S. Beley, A. V. Koloskov, P. V. Ponomarenko, and O. F. Tyrnov, HF radar observations of decaying artificial field aligned irregularities, J. Geophys. Res. , 101, 26,981, 1996.

  11. Court Remands as a Percentage of New Court Cases Filed

    Data.gov (United States)

    Social Security Administration — Longitudinal report detailing the numbers and percentages of court remand actions received during each Fiscal Year 2010 - onward as compared to the total number of...

  12. Social Security Administration Percentage of Fast-Track Receipts

    Data.gov (United States)

    Social Security Administration — The dataset provides the percentage of fast-track receipts by state during the reporting fiscal year. Fast-tracked cases consist of those cases identified as Quick...

  13. Dynamics of control mechanisms in a cost plus percentage contract

    OpenAIRE

    Huang, Wen-Haw; Yin, Samuel Yen-Lian; Tserng, H. Ping

    2012-01-01

    While the control mechanisms of incentive contracts have been widely studied, this study attempts to determine the optimal control over a cost-plus percentage contract of a construction project. Cost-plus percentage contract shifts some risk from the contractor to client, thus offering little incentive for the contractor to control costs. The owner requires additional management over the construction project to ensure that only necessary costs are spent. The data are collected through documen...

  14. Evaluation of natural smile: Golden proportion, RED or Golden percentage

    OpenAIRE

    Murthy, B. V. Sreenivasan; Ramani, Niketa

    2008-01-01

    Creating geometric or mathematical proportion to relate the successive width of maxillary anterior teeth is a critical aspect in Esthetic dentistry. Golden proportion, recurring esthetic dental (RED) proportion and golden percentage are new theories in this field. Aim: To investigate the existence and suitability of Golden proportion, Recurring Esthetic Dental, and Golden percentage between the widths of maxillary anterior teeth in individuals with natural dentition, with the aid of digital p...

  15. Characterization of grain sizes and roughness of HfOsub>2sub> single layers.

    Science.gov (United States)

    Zhang, Lei; Cheng, Xinbin; Zhang, Jinlong; Jiao, Hongfei; Bao, Ganghua; Ding, Tao; Wang, Zhanshan

    2017-02-01

    The grain sizes and their influence on the roughness of an HfOsub>2sub> single layer prepared with ion-assisted deposition were investigated. Three methods, x ray diffractometry, atomic force microscopy, and the k-correlated power spectral density function model, were used to obtain the grain sizes in two HfOsub>2sub> single layers with 16 and 20 nm thicknesses. X ray diffractometry showed that the grain sizes were about 7 and 9 nm, respectively, whereas the other two methods demonstrated that the grain sizes were about 14 and 16 nm. It was thought that x ray diffractometry underestimated the grain size due to micro strain or a shallow penetration depth. The grains in an HfOsub>2sub> single layer lead to a rough surface, which had a significant bulge at the middle-high frequency range in a power spectral density function curve. The coating intrinsic roughness of the HfOsub>2sub> single layer was separated from the substrate roughness.

  16. REMPI Spectroscopy of HfF

    CERN Document Server

    Loh, Huanqian; Yahn, Tyler S; Looser, Herbert; Field, Robert W; Cornell, Eric A

    2012-01-01

    The spectrum of electronic states at 30000--33000 cm$^{-1}$ in hafnium fluoride has been studied using (1+1) resonance-enhanced multi-photon ionization (REMPI) and (1+1$'$) REMPI. Six $\\Omega' = 3/2$ and ten $\\Pi_{1/2}$ vibronic bands have been characterized. We report the molecular constants for these bands and estimate the electronic energies of the excited states using a correction derived from the observed isotope shifts. When either of two closely spaced $\\Pi_{1/2}$ electronic states is used as an intermediate state to access autoionizing Rydberg levels, qualitatively distinct autoionization spectra are observed. The intermediate state-specificity of the autoionization spectra bodes well for the possibility of using a selected $\\Pi_{1/2}$ state as an intermediate state to create ionic HfF$^+$ in various selected quantum states, an important requirement for our electron electric dipole moment (eEDM) search in HfF$^+$.

  17. Digitally Driven Antenna for HF Transmission

    Science.gov (United States)

    2010-09-01

    the 1-MHz carrier signal. This signal is then fed into the base terminals of an NPN/ PNP transistor pair arranged in a push–pull configura- tion. A dual...negative voltage connected to the collector terminal of the PNP transistor . Since it was not possible to explicitly simulate the radia- tion of the time...complementary pair of switching transistors is driven with a pulsewidth modulated HF signal, eliminating the requirement for a frequency-dependent

  18. RFID UHF i HF w bibliotekach

    Directory of Open Access Journals (Sweden)

    Gładysz Bartłomiej

    2015-06-01

    Full Text Available The potential of the innovative Radio Frequency Identification (RFID technology to be applied for support, acceleration and automation of the circulation process of library collection is presented. Technology basics, and hardware and software components are described. Two different radio standards used in libraries are compared. The goal is to present the potential of RFID technology for libraries, to highlight the differences and to build a basis for further consideration of UHF and HF alternatives.

  19. Evaluation of natural smile: Golden proportion, RED or Golden percentage.

    Science.gov (United States)

    Murthy, B V Sreenivasan; Ramani, Niketa

    2008-01-01

    Creating geometric or mathematical proportion to relate the successive width of maxillary anterior teeth is a critical aspect in Esthetic dentistry. Golden proportion, recurring esthetic dental (RED) proportion and golden percentage are new theories in this field. To investigate the existence and suitability of Golden proportion, Recurring Esthetic Dental, and Golden percentage between the widths of maxillary anterior teeth in individuals with natural dentition, with the aid of digital photographs and computer analysis. Standardized frontal images of 56 dental students, 20 male and 36 female, were captured. Each maxillary anterior tooth was digitally measured. Once the measurements were recorded, the three theories were applied and the data was analyzed statistically. The golden proportion was found to exist only in 14-25% of the subjects, between perceived maxillary anterior teeth in natural dentition. The value of RED proportion was not constant, and as one moved distally, this proportion gradually increased. Furthermore, the results revealed that golden percentage was rather constant in terms of relative tooth width. Central incisor represented 22%, lateral incisor 15% and canine 13% of the width of six maxillary anterior teeth, as viewed from the front. Both golden proportion and RED proportion are unsuitable methods to relate the successive width of the maxillary anterior teeth in natural dentition. However, the golden percentage theory can be applied if percentages are adjusted, taking into consideration the ethnicity of the population.

  20. Economic Consequences of DifferentLean Percentage Estimation Methods

    Directory of Open Access Journals (Sweden)

    Zdravko Tolušić

    2003-06-01

    Full Text Available The economic effects of the choice of two different lean percentage estimation methods and terminal sire breed were investigated on 53 pig carcasses divided in two groups. In the 1st group were progeny of Pietrain used as terminal sire (n=25 and in 2nd the progeny of Large White terminal sire. It was found that the breed of terminal sire haven.t had influence on cold carcass weight and fat thickness measured for TP method of lean percentage estimation. Inclusion of Pietrain as terminal sire had influence on MLD thickness measured for TP and INS methods which was significantly higher, while fat thickness measured for instrumental method was significantly lower (p<0.01. Carcasses of the same group had higher lean percentage estimated by TP and INS methods (p<0.05 and p<0.01, resp.. Also, different methods of lean percentage estimation resulted in different classification of the carcasses into SEUROP classes. The choice of the lean percentage estimation method had no significant effect on the price of the carcasses from 2nd group which had Large White as terminal sire, while in pig carcasses from the 1st group (Pietrain as terminal sire, the choice of lean percentage method of estimation determined the price of the carcasses, and by this also economic surplus (or loss of the producers. It is concluded that both methods are equally applicable in the case of Large White crossbreeds, while caution should be taken in the case of pig carcasses originated from Pietrain as terminal sire because carcasses of such pigs reached higher prices when estimated by instrumental method.

  1. HF-enhanced 4278-Å airglow: evidence of accelerated ionosphere electrons?

    Science.gov (United States)

    Fallen, C. T.; Watkins, B. J.

    2013-12-01

    We report calculations from a one-dimensional physics-based self-consistent ionosphere model (SCIM) demonstrating that HF-heating of F-region electrons can produce 4278-Å airglow enhancements comparable in magnitude to those reported during ionosphere HF modification experiments at the High-frequency Active Auroral Research Program (HAARP) observatory in Alaska. These artificial 'blue-line' emissions, also observed at the EISCAT ionosphere heating facility in Norway, have been attributed to arise solely from additional production of N2+ ions through impact ionization of N2 molecules by HF-accelerated electrons. Each N2+ ion produced by impact ionization or photoionization has a probability of being created in the N2+(1N) excited state, resulting in a blue-line emission from the allowed transition to its ground state. The ionization potential of N2 exceeds 18 eV, so enhanced impact ionization of N2 implies that significant electron acceleration processes occur in the HF-modified ionosphere. Further, because of the fast N2+ emission time, measurements of 4278-Å intensity during ionosphere HF modification experiments at HAARP have also been used to estimate artificial ionization rates. To the best of our knowledge, all observations of HF-enhanced blue-line emissions have been made during twilight conditions when resonant scattering of sunlight by N2+ ions is a significant source of 4278-Å airglow. Our model calculations show that F-region electron heating by powerful O-mode HF waves transmitted from HAARP is sufficient to increase N2+ ion densities above the shadow height through temperature-enhanced ambipolar diffusion and temperature-suppressed ion recombination. Resonant scattering from the modified sunlit region can cause a 10-20 R increase in 4278-Å airglow intensity, comparable in magnitude to artificial emissions measured during ionosphere HF-modification experiments. This thermally-induced artificial 4278-Å aurora occurs independently of any artificial

  2. UHF Radar observations at HAARP with HF pump frequencies near electron gyro-harmonics and associated ionospheric effects

    Science.gov (United States)

    Watkins, Brenton; Fallen, Christopher; Secan, James

    Results for HF modification experiments at the HAARP facility in Alaska are presented for experiments with the HF pump frequency near third and fourth electron gyro-harmonics. A UHF diagnostic radar with range resolution of 600 m was used to determine time-dependent altitudes of scattering from plasma turbulence during heating experiments. Experiments were conducted with multiple HF frequencies stepped by 20 kHz above and below the gyro-harmonic values. During times of HF heating the HAARP facility has sufficient power to enhance large-scale ionospheric densities in the lower ionosphere (about 150-200 km altitude) and also in the topside ionosphere (above about 350 km). In the lower ionosphere, time-dependent decreases of the altitude of radar scatter result from electron density enhancements. The effects are substantially different even for relatively small frequency steps of 20 kHz. In all cases the time-varying altitude decrease of radar scatter stops about 5-10 km below the gyro-harmonic altitude that is frequency dependent; we infer that electron density enhancements stop at this altitude where the radar signals stop decreasing with altitude. Experiments with corresponding total electron content (TEC) data show that for HF interaction altitudes above about 170 km there is substantial topside electron density increases due to upward electron thermal conduction. For lower altitudes of HF interaction the majority of the thermal energy is transferred to the neutral gas and no significant topside density increases are observed. By selecting an appropriate HF frequency a little greater than the gyro-harmonic value we have demonstrated that the ionospheric response to HF heating is a self-oscillating mode where the HF interaction altitude moves up and down with a period of several minutes. If the interaction region is above about 170 km this also produces a continuously enhanced topside electron density and upward plasma flux. Experiments using an FM scan with the HF

  3. Guidelines for Statistical Analysis of Percentage of Syllables Stuttered Data

    Science.gov (United States)

    Jones, Mark; Onslow, Mark; Packman, Ann; Gebski, Val

    2006-01-01

    Purpose: The purpose of this study was to develop guidelines for the statistical analysis of percentage of syllables stuttered (%SS) data in stuttering research. Method; Data on %SS from various independent sources were used to develop a statistical model to describe this type of data. On the basis of this model, %SS data were simulated with…

  4. 78 FR 48789 - Loan Guaranty: Percentage to Determine Net Value

    Science.gov (United States)

    2013-08-09

    ... AFFAIRS Loan Guaranty: Percentage to Determine Net Value AGENCY: Department of Veterans Affairs (VA... component of this is the ``net value'' of the property to the Government, as defined in 38 CFR 36.4301. Essentially ``net value'' is the fair market value of the property, minus the total costs the...

  5. A novel three-phase UPS system with a single-phase resonant HF link

    OpenAIRE

    Darwish, MK

    2006-01-01

    This paper presents a new three-phase uninterruptible power supply (UPS) system based on a single-phase resonant high frequency (HF) link and a single-phase transformer. The three-phase output voltage is constructed and regulated from a three-phase cycloconverter fed from the constant amplitude, constant frequency link voltage. The generation of a novel switching stategy for the three-phase cycloconverter is presented. The simulation of the proposed system is carried out and verified with exp...

  6. Artificial ducts caused by HF heating of the ionosphere by HAARP

    OpenAIRE

    Vartanyan, A.; Milikh, G. M.; Mishin, E.; Parrot, Michel; Galkin, I.; Reinisch, B; Huba, J.; Joyce, G.; Papadopoulos, K.

    2012-01-01

    International audience; We report on satellite observations of plasma density enhancements (ducts) in thetopside ionosphere during four HAARP/BRIOCHE campaigns during 2009–2010.Artificial ducts, caused by high-power HF radio wave injections from the HAARPtransmitter toward the magnetic zenith, are detected by the DEMETER and DMSPsatellites on a regular basis when there is a perceptible ionospheric F2 peak density.Overall, the plasma density enhancements detected between 0930 and 1230 LT varie...

  7. Artificial ducts caused by HF heating of the ionosphere by HAARP

    OpenAIRE

    Vartanyan, A.; Milikh, G. M.; E. Mishin; Parrot, Michel; Galkin, I.; B. Reinisch; Huba, J.; Joyce, G.; Papadopoulos, K.

    2012-01-01

    International audience; We report on satellite observations of plasma density enhancements (ducts) in thetopside ionosphere during four HAARP/BRIOCHE campaigns during 2009–2010.Artificial ducts, caused by high-power HF radio wave injections from the HAARPtransmitter toward the magnetic zenith, are detected by the DEMETER and DMSPsatellites on a regular basis when there is a perceptible ionospheric F2 peak density.Overall, the plasma density enhancements detected between 0930 and 1230 LT varie...

  8. Influence of HF acid catalyst concentration on properties of aerogel low-k thin films

    Science.gov (United States)

    Gaikwad, A. S.; Gupta, S. A.; Mahajan, A. M.

    2016-08-01

    The effect of hydrofluoric acid (HF) catalyst concentration in coating solution on chemical, physical and structural properties of silica aerogel thin films was investigated. The aerogel films were synthesized by using a sol-gel spin coating method followed by aging in ethanol and CO2 supercritical drying. The refractive index (RI) is observed to be reduced from 1.32 to 1.13 and porosity percentage increased from 30.21% to 71.64% in accordance with increasing HF concentration. Deposition of silica aerogel was confirmed from Fourier transform infrared spectroscopy measurement. The nanoporous nature of deposited films was confirmed from field effect scanning electron microscopy and observed pore diameter is in the range of 3.33 to 6.69 nm. The nanoporous nature of the film was also validated from atomic force microscopy and root mean square roughness was observed to be increased from 2.31 nm to 3.2 nm with increasing acid catalyst concentration in the coating solution. The calculated dielectric constant from CV measurement of fabricated metal-insulator-semiconductor structure for the silica aerogel formed at 0.8 ml HF concentration is observed to be 1.73. These deposited nanoporous silica aerogel low-k films with lower k value and smaller pore size have application as interlayer dielectric materials to minimize the disadvantages of porous materials.

  9. Pancreatic Cancer: 80 Years of Surgery—Percentage and Repetitions

    Directory of Open Access Journals (Sweden)

    Birgir Gudjonsson

    2016-01-01

    Full Text Available Objective. The incidence of pancreatic cancer is estimated to be 48,960 in 2015 in the US and projected to become the second and third leading causes of cancer-related deaths by 2030. The mean costs in 2015 may be assumed to be $79,800 per patient and for each resection $164,100. Attempt is made to evaluate the results over the last 80 years, the number of survivors, and the overall survival percentage. Methods. Altogether 1230 papers have been found which deal with resections and reveal survival information. Only 621 of these report 5-year survivors. Reservation about surgery was first expressed in 1964 and five-year survival of nonresected survivors is well documented. Results. The survival percentage depends not only on the number of survivors but also on the subset from which it is calculated. Since the 1980s the papers have mainly reported the number of resections and survival as actuarial percentages, with or without the actual number of survivors being reported. The actuarial percentage is on average 2.75 higher. Detailed information on the original group (TN, number of resections, and actual number of survivors is reported in only 10.6% of the papers. Repetition occurs when the patients from a certain year are reported several times from the same institution or include survivors from many institutions or countries. Each 5-year survivor may be reported several times. Conclusion. Assuming a 10% resection rate and correcting for repetitions and the life table percentage the overall actual survival rate is hardly more than 0.3%.

  10. Reliability study of Zr and Al incorporated Hf based high-k dielectric deposited by advanced processing

    Science.gov (United States)

    Bhuyian, Md Nasir Uddin

    electron affinity variation in HfO2 and ZrO 2. The trap activation energy levels estimated from the temperature dependent current voltage characteristics also support the observed reliability characteristics for these devices. In another experiment, HfO2 is lightly doped with Al with a variation in Al concentration by depositing intermediate HfAlOx layers. This work has demonstrated a high quality HfO2 based gate stack by depositing atomic layer deposited (ALD) HfAlOx along with HfO2 in a layered structure. In order to get multifold enhancement of the gate stack quality, both Al percentage and the distribution of Al are observed by varying the HfAlOx layer thickness and it is found that < 2% Al/(Al+Hf)% incorporation can result in up to 18% reduction in the average EOT along with up to 41% reduction in the gate leakage current as compared to the dielectric with no Al content. On the other hand, excess Al presence in the interfacial layer moderately increases the interface state density (Dit). When devices are stressed in the gate injection mode at a constant voltage stress, dielectrics with Al/(Hf+Al)% < 2% show resistance to stress induced flat-band voltage shift (DeltaVFB), and stress induced leakage current (SILC). The time dependent dielectric breakdown (TDDB) characteristics show a higher charge to breakdown and an increase in the extracted Weibull slope (beta) that further confirms an enhanced dielectric reliability for devices with < 2% Al/(Al+Hf)%.

  11. Improvements on Signal Processing for HF Radar

    Institute of Scientific and Technical Information of China (English)

    LIU Yongtan; SHEN Yiying

    2001-01-01

    In this paper improvements on signalprocessing are achieved to enhance the performancesof H-F radar system, being unobtainable by the con-ventional signal processing. Using the improved sig-nal processing both high range resolution and longcoherent integration time may be obtained for goodbenefit to the target resolution and weak signal de-tection. Modification to the unmatched correspon-dence between range delay samples and range resolu-tion ceils saves an additional accumulation loss in therange processing. Finally, comparisons between theimproved and the conventional signal processing aregiven by numerical simulation.

  12. New Adaptive Data Transmission Scheme Over HF Radio

    Directory of Open Access Journals (Sweden)

    Adil H. Ahmad

    2008-01-01

    Full Text Available Acceptable Bit Error rate can be maintained by adapting some of the design parameters such as modulation, symbol rate, constellation size, and transmit power according to the channel state.An estimate of HF propagation effects can be used to design an adaptive data transmission system over HF link. The proposed system combines the well known Automatic Link Establishment (ALE together with variable rate transmission system. The standard ALE is modified to suite the required goal of selecting the best carrier frequency (channel for a given transmission. This is based on measuring SINAD (Signal plus Noise plus Distortion to Noise plus Distortion, RSL (Received Signal Level, multipath phase distortion and BER (Bit Error Rate for each channel in the frequency list. Channel condition evaluation is done by two arrangements. In the first an FFT analysis is used where a pilot signal is transmitted over the channel, while the data itself is used in the second arrangement. Passive channel assessment is used to avoid bad channels hence limiting the frequency pool size to be used in the point to point communication and the time required for scanning and linking. An exchange of channel information between the transmitting and receiving stations is considered to select the modulation scheme for transmission. Mainly MPSK and MFSK are considered with different levels giving different data rate according to the channel condition. The results of the computer simulation have shown that when transmitting at a fixed channel symbol rate of 1200 symbol/sec, the information rate ranges from 2400 bps using 4FSK up to 3600 bps using 8PSK for SNR ranges from 11dB up to 26dB.

  13. Determining Energy Distributions of HF-Accelerated Electrons at HAARP

    Science.gov (United States)

    2015-11-18

    AFRL-AFOSR-VA-TR-2015-0383 Determining energy distributions of HF-accelerated electrons at HAARP Christopher Fallen University of Alaska Fairbanks...2012 - 11/14/2015 4. TITLE AND SUBTITLE Determining energy distributions of HF-accelerated electrons at HAARP 5a. CONTRACT NUMBER FA9550-12-1-0424...transmitted from the High-frequency Active Auroral Research Program ( HAARP ) transmitter in Alaska. For a given fixed HF-plasma interaction altitude

  14. PEMISAHAN Zr – Hf SECARA SINAMBUNG MENGGUNAKAN MIXER SETTLER

    Directory of Open Access Journals (Sweden)

    Dwi Biyantoro

    2017-01-01

    Full Text Available ABSTRAK PEMISAHAN Zr – Hf SECARA SINAMBUNG MENGGUNAKANMIXER SETTLER. Telah dilakukan pemisahanZr – Hf secara sinambung menggunakan pengaduk pengenap (mixer settler 16 stage. Larutan umpan adalah zirkon nitrat dengan kadar Zr = 30786 ppm dan Hf = 499 ppm. Ekstraktan dipakai adalah solven 60 % TBP dalam kerosen dan larutan scrubbingyang dipakai adalah asam nitrat 1 M. Umpan masuk pada stageke 5 dikontakkan secara berlawanan arah dengan solven masuk pada stage ke 16 dan larutan scrubbing masuk pada stage ke 1. Tujuan penelitian ini adalah memisahkan unsur Zr dan Hf dari hasil olah pasir zirkon menggunakan solven TBP dengan alat mixer settler16 stage. Analisis umpan dan hasil proses pemisahan untuk zirkonium (Zr dilakukan dengan menggunakan alat pendar sinar-X, sedangkananalisis unsur hafnium (Hf menggunakan Analisis Pengaktifan Neutron (APN. Parameter penelitian dilakukan dengan variasi keasaman asam nitrat dalam umpan dan variasi waktu pada berbagai laju pengadukan. Hasil penelitian pemisahan unsur Zr dengan Hf diperolehkondisi optimum pada keasaman umpan 4 N HNO3, keseimbangan dicapai setelah 3jam dan laju pengadukan 3300 rpm. Hasil ekstrak  unsur zirkon (Zr diperoleh kadar sebesar 28577 ppm dengan efisiensi 92,76 % serta kadar pengotor hafnium (Hf sebesar 95 ppm. Kata Kunci: pemisahan Zr, Hf, ekstraksi, mixer settler, alat pendar sinar-X, APN. ABSTRACT SEPARATION of Zr - Hf CONTINUOUSLY USE THE MIXER SETTLER. Separation of Zr - Hf continuously using mixer settler 16 stage has been done. The feed solution is zircon nitrate concentration of Zr = 30786 ppm  and Hf = 499 ppm. As the solvent used extractant 60 % TBP in 40 % kerosene. Nitric acid solution used srubbing 1 M. The feed entered into stage to 5 is contacted with solvents direction on the stage to 16 and the scrubbing solution enter the stage to 1. The purpose of this study is to separate Zr and Hf of the results from the process of zircon sand using solvent TBP using 16 stage

  15. Mitigating Doppler shift effect in HF multitone data modem

    Science.gov (United States)

    Sonlu, Yasar

    1989-09-01

    Digital communications over High Frequency (HF) radio channels are getting important in recent years. Current HF requirements are for data transmission at rates 2.4 kbps or more to accommodate computer data links and digital secure voice. HF modems which were produced to meet these speeds are, serial modems and parallel modems. On the other hand, the HF sky-wave communication medium, the ionosphere, has some propagation problems such as multipath and Doppler shift. The effect of Doppler shift in a parallel modem which employs Differential Quadrature Phase Shift Keying (DQPSK) modulation is considered and a correction method to mitigate the Doppler Shift effect is introduced.

  16. Epitaxial Thin Films of Y doped HfO2

    Science.gov (United States)

    Serrao, Claudy; Khan, Asif; Ramamoorthy, Ramesh; Salahuddin, Sayeef

    Hafnium oxide (HfO2) is one of a few metal oxides that is thermodynamically stable on silicon and silicon oxide. There has been renewed interest in HfO2 due to the recent discovery of ferroelectricity and antiferroelectricity in doped HfO2. Typical ferroelectrics - such as strontium bismuth tantalate (SBT) and lead zirconium titanate (PZT) - contain elements that easily react with silicon and silicon oxide at elevated temperatures; therefore, such ferroelectrics are not suited for device applications. Meanwhile, ferroelectric HfO2 offers promise regarding integration with silicon. The stable phase of HfO2 at room temperature is monoclinic, but HfO2 can be stabilized in the tetragonal, orthorhombic or even cubic phase by suitable doping. We stabilized Y-doped HfO2 thin films using pulsed laser deposition. The strain state can be controlled using various perovskite substrates and controlled growth conditions. We report on Y-doped HfO2 domain structures from piezo-response force microscopy (PFM) and structural parameters via X-ray reciprocal space maps (RSM). We hope this work spurs further interest in strain-tuned ferroelectricity in doped HfO2.

  17. Microstructural characterization of as-cast hf-b alloys

    Directory of Open Access Journals (Sweden)

    João Carlos Jânio Gigolotti

    2012-04-01

    Full Text Available An accurate knowledge of several metal-boron phase diagrams is important to evaluation of higher order systems such as metal-silicon-boron ternaries. The refinement and reassessment of phase diagram data is a continuous work, thus the reevaluation of metal-boron systems provides the possibility to confirm previous data from an investigation using higher purity materials and better analytical techniques. This work presents results of rigorous microstructural characterization of as-cast hafnium-boron alloys which are significant to assess the liquid composition associated to most of the invariant reactions of this system. Alloys were prepared by arc melting high purity hafnium (minimum 99.8% and boron (minimum 99.5% slices under argon atmosphere in water-cooled copper crucible with non consumable tungsten electrode and titanium getter. The phases were identified by scanning electron microscopy, using back-scattered electron image mode and X-ray diffraction. In general, a good agreement was found between our data and those from the currently accepted Hafnium-Boron phase diagram. The phases identified are αHfSS and B-RhomSS, the intermediate compounds HfB and HfB2 and the liquide L. The reactions are the eutectic L ⇔ αHfSS + HfB and L ⇔ HfB2 + B-Rhom, the peritectic L + HfB2 ⇔ HfB and the congruent formation of HfB2.

  18. A DFT study of temperature dependent dissociation mechanism of HF in HF(H2O)7 cluster

    Indian Academy of Sciences (India)

    Swatantra K Yadav; Hirdyesh Mishra; Ashwani K Tiwari

    2015-10-01

    We report a Density Functional Theoretical (DFT) study of dissociation of Hydrogen Fluoride (HF) in HF(H2O)7 cluster, using B3LYP functional and empirical exchange correlation functional M06-2X along with 6-31+G(d,p) basis set. Dissociation constant, KRP, of HF dissociation and pKa values of HF in cluster at various temperatures have been reported. It has been found that both KRP and pKa are highly dependent on temperature. The variation of pKa with temperature suggests that HF is strong acid at lower temperatures. Our study also reveals that HF is a stronger acid in water cluster than in bulk water. Further, the results obtained by DFT calculations have been compared with the earlier reported results obtained from Monte Carlo (MC) simulation. It is found that DFT results are qualitatively consistent with the results of MC simulation but quantitatively different.

  19. Percentage of microbeads in pelagic microplastics within Japanese coastal waters.

    Science.gov (United States)

    Isobe, Atsuhiko

    2016-09-15

    To compare the quantity of microbeads with the quantity of pelagic microplastics potentially degraded in the marine environment, samples were collected in coastal waters of Japan using neuston nets. Pelagic spherical microbeads were collected in the size range below 0.8mm at 9 of the 26 stations surveyed. The number of pelagic microbeads smaller than 0.8mm accounted for 9.7% of all microplastics collected at these 9 stations. This relatively large percentage results from a decrease in the abundance of microplastics smaller than 0.8mm in the upper ocean, as well as the regular loading of new microbeads from land areas, in this size range. In general, microbeads in personal care and cosmetic products are not always spherical, but rather are often a variety of irregular shapes. It is thus likely that this percentage is a conservative estimate, because of the irregular shapes of the remaining pelagic microbeads.

  20. Hf-W chronometry of primitive achondrites

    Science.gov (United States)

    Schulz, T.; Münker, C.; Mezger, K.; Palme, H.

    2010-03-01

    Metal segregation and silicate melting on asteroids are the most incisive differentiation events in the early evolution of planetary bodies. The timing of these events can be constrained using the short-lived 182Hf- 182W radionuclide system. Here we present new 182Hf- 182W data for major types of primitive achondrites including acapulcoites, winonaites and one lodranite. These meteorites are of particular interest because they show only limited evidence for partial melting of silicates and are therefore intermediate between chondrites and achondrites. For acapulcoites we derived a 182Hf- 182W age of Δ tCAI = 4.1 +1.2/ -1.1 Ma. A model age for winonaite separates calculated from the intercept of the isochron defines an age of Δ tCAI = 4.8 +3.1/ -2.6 Ma (assuming a bulk Hf/W ratio of ˜1.2). Both ages most likely define primary magmatic events on the respective parent bodies, such as melting of metal, although metal stayed in place and did not segregate to form a core. A later thermal event is responsible for resetting of the winonaite isochron, yielding an age of Δ tCAI = 14.3 +2.7/ -2.2 Ma, significantly younger than the model age. Assuming a co-genetic relationship between winonaites and silicates present in IAB iron meteorites (based on oxygen isotope composition) and including data by Schulz et al. (2009), a common parent body chronology can be established. Magmatic activity occurred between ˜1.5 and 5 Ma after CAIs. More than 5 Ma later, intensive thermal metamorphism has redistributed Hf-W. Average cooling rates calculated for the winonaite/IAB parent asteroid range between ˜35 and ˜4 K/Ma, most likely reflecting different burial depths. Cooling rates obtained for acapulcoites were ˜40 K/Ma to ˜720 K and then ˜3 K/Ma to ˜550 K. Accretion and subsequent magmatism on the acapulcoite parent body occurred slightly later if compared to most achondrite parent bodies (e.g., angrites, ureilites and eucrites), in this case supporting the concept of an inverse

  1. Pressure induced novel compounds in the Hf-O system from first-principles calculations

    OpenAIRE

    2015-01-01

    Using first-principles evolutionary simulations, we have systematically investigated phase stability in the Hf-O system at pressure up to 120 GPa. New compounds Hf5O2, Hf3O2, HfO and HfO3 are discovered to be thermodynamically stable at certain pressure ranges and a new stable high-pressure phase is found for Hf2O with space group Pnnm and anti-CaCl2-type structure. Both P62m-HfO and P4m2-Hf2O3 show semimetallic character. Pnnm-HfO3 shows interesting structure, simultaneously containing oxide...

  2. Ferroelectricity of nondoped thin HfO2 films in TiN/HfO2/TiN stacks

    Science.gov (United States)

    Nishimura, Tomonori; Xu, Lun; Shibayama, Shigehisa; Yajima, Takeaki; Migita, Shinji; Toriumi, Akira

    2016-08-01

    We report on the impact of TiN interfaces on the ferroelectricity of nondoped HfO2. Ferroelectric properties of nondoped HfO2 in TiN/HfO2/TiN stacks are shown in capacitance-voltage and polarization-voltage characteristics. The Curie temperature is also estimated to be around 500 °C. The ferroelectricity of nondoped HfO2 clearly appears by thinning HfO2 film down to ˜35 nm. We directly revealed in thermal treatments that the ferroelectric HfO2 film on TiN was maintained by covering the top surface of HfO2 with TiN, while it was followed by a phase transition to the paraelectric phase in the case of the open surface of HfO2. Thus, it is concluded that the ferroelectricity in nondoped HfO2 in this study was mainly driven by both of top and bottom TiN interfaces.

  3. Combined U-Pb and Lu-Hf isotope analyses by laser ablation MC-ICP-MS: methodology and applications

    Energy Technology Data Exchange (ETDEWEB)

    Matteini, Massimo; Dantas, Elton L.; Pimentel, Marcio M.; Bühn, Bernhard, E-mail: massimo@unb.br [Universidade de Brasilia (UnB), DF (Brazil). Instituto de Geociencias

    2010-06-15

    The Lutetium-Hafnium isotopic system represents one of the most innovative and powerful tools for geochronology and isotopic studies. Combined U-Pb and Lu-Hf in situ analyses on zircon by LA-MC-ICP-MS permit to characterize isotopically the host magma from which it crystallized furnishing significant information for sediment provenance and crustal evolution studies. In this paper e describe the Lu-Hf systematic by LA-MC-ICP-MS developed in the laboratory of Geochronology of the University of Brasilia and report the results obtained by repeated analyses of {sup 176}Hf/{sup 177}Hf isotopic ratio of three zircon standards: GJ-1 = 0.282022 ± 11 (n=56), Temora 2 = 0.282693 ± 14 (n=25) and UQZ = 0.282127 ± 33 (n=11). The {sup 176}Hf/{sup 177}Hf ratio (0.282352 ± 22, n=14) of gem quality zircon used as in-house standard have been also characterized. As a geological application, we analyzed two complex zircons selected from a migmatitic rocks from the Borborema Province, NE Brazil. On the basis of U-Pb and Lu-Hf data, two main crystallization events have been identified in both studied zircons. An older event at ca. 2.05 Ga recognized in the inherited cores represents a well-characterized paleoproterozoic magmatic event that affected the whole Borborema Province. A second crystallization event at ∼ 575 Ma, recognized at the rims, represents a Neoproterozoic (Brazilian) high grade metamorphic-magmatic event. (author)

  4. Band structure and electrical properties of MBE grown HfO{sub 2} - based alkaline earth Perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Peter, Dudek; Grzegorz, Lupina; Grzegorz, Kozlowski; Jarek, Dabrowski; Gunther, Lippert; Hans-Joachim, Muessig; Thomas, Schroeder [IHP-Microelectronics, Frankfurt, Oder (Germany); Dieter, Schmeisser [BTU, Cottbus (Germany)

    2010-07-01

    Ultra thin dielectric films (<20 nm) deposited on TiN electrodes are interesting for MIM capacitor application. High capacitance density and dielectric permittivity must be accompanied by extremely low leakage currents (10{sup -8} A/cm{sup 2}) at bias 0.5 V. To achieve such low leakage currents, high band gap and proper band alignment is required. Occupied electronic states can be probed with standard laboratory photoemission methods. Probing of unoccupied states is more challenging. Synchrotron based PES in combination with XAS forms a powerful method to study the band alignment. ASAM end station located at the U 49/2 PGM 2 beamline of BESSY II (Berlin) offers excellent conditions for performing such measurements. We investigated HfO{sub 2} - based alkaline earth perovskite - BaHfO{sub 3} with subsequent admixture of TiO{sub 2}, resulting in formation of BaHf{sub 0.5}Ti{sub 0.5}O{sub 3} compound. The analysis of data indicates that band gap for HfO{sub 2} is similar to BaHfO{sub 3} and amounts 5.8 eV; for BaHf{sub 0.5}Ti{sub 0.5}O{sub 3} it decreases to 3.8 eV. We conclude that the addition of TiO{sub 2} to BaHfO{sub 3} increases significantly the dielectric permittivity but also impacts the band gap alignment. The conduction band offset shrinks, influencing the leakage current behavior.

  5. Synthesis of Freestanding HfO2 Nanostructures

    Science.gov (United States)

    2011-04-05

    Tang J, Fabbri J, Robinson RD, Zhu Y, Herman IP, Steigerwald ML, Brus LE: Solid-solution nanoparticles:use of a nonhydrolytic sol-gel synthesis to...colloidal HfO2 nanorods. Adv Mater 2007, 19:2608-2612. Page 21 5. Qiu X, Howe JY, Cardoso MB, Polat O, Heller W: Size control of highly ordered HfO2

  6. Parametric excitation of whistler waves by HF heater

    Science.gov (United States)

    Kuo, S. P.; Lee, M. C.

    1989-01-01

    Possible generation of whistler waves by Tromso HF heater is investigated. It is shown that the HF heater wave can parametrically decay into a whistler wave and a Langmuir wave. Since whistler waves may have a broad range of frequency, the simultaneously excited Langmuir waves can have a much broader frequency bandwidth than those excited by the parametric decay instability.

  7. Study of {sup 179}Hf{sup m2} excitation

    Energy Technology Data Exchange (ETDEWEB)

    Vishnevsky, I. N.; Zheltonozhsky, V. A., E-mail: zhelton@kinr.kiev.ua; Savrasov, A. N. [National Academy of Sciences of Ukraine, Institute for Nuclear Research (Ukraine); Mazur, V. M. [National Academy of Sciences of Ukraine, Institute of Electronic Physics (Ukraine)

    2016-12-15

    Isomeric ratios of {sup 179}Hf{sup m2,g} yields in the (γ, n) reaction and the cross section for the {sup 179}Hf{sup m2} population in the (α, p) reaction are measured for the first time at the end-point energies of 15.1 and 17.5 MeV for bremsstrahlung photons and 26 MeV for alpha particles. The results are σ = (1.1 ± 0.11) × 10{sup −27} cm{sup 2} for the {sup 176}Lu(α, p){sup 179}Hf{sup m2} reaction and Y{sub m2}/Y{sub g} = (6.1 ± 0.3) × 10{sup −6} and (3.7 ± 0.2) × 10{sup −6} for the {sup 180}Hf(γ, n){sup 179}Hf{sup m22} reaction at E{sub ep} =15.1 and 17.5 MeV, respectively. The experimental data on the relative {sup 179}Hf{sup m2} yield indicate a single-humped shape of the excitation function for the {sup 180}Hf(γ, n){sup 179}Hf{sup m2} reaction. Simulation is performed using the TALYS-1.4 and EMPIRE-3.2 codes.

  8. Diffusion of Hf and Nb in Zr-19%Nb

    Energy Technology Data Exchange (ETDEWEB)

    Zou, H. [Atomic Energy of Canada Ltd., Chalk River, ON (Canada). Chalk River Nuclear Labs.; Hood, G.M. [Atomic Energy of Canada Ltd., Chalk River, ON (Canada). Chalk River Nuclear Labs.; Schultz, R.J. [Atomic Energy of Canada Ltd., Chalk River, ON (Canada). Chalk River Nuclear Labs.; Matsuura, N. [Atomic Energy of Canada Ltd., Chalk River, ON (Canada). Chalk River Nuclear Labs.; Roy, J.A. [Atomic Energy of Canada Ltd., Chalk River, ON (Canada). Chalk River Nuclear Labs.; Jackman, J.A. [CANMET, Ottawa, Ont. (Canada). Met. Sci. and Technol.

    1996-05-01

    Diffusion of Hf and Nb in large-grained bcc Zr-19%Nb has been studied. Diffusion coefficients of Hf, D(Hf), were measured in the range 620-1173 K and D(Nb) was measured at 920 and 1167 K. The Hf diffusion profiles were determined by SIMS and the Nb profiles by microtome sectioning and radio-tracer counting. The Hf data show a smooth, temperature-dependent behaviour through the monotectoid temperature, 875 K, and may be characterised by D{approx}10{sup -9}.exp-1.4 (eV/kT) m{sup 2}/s. D(Nb) tends to be lower than the corresponding values for D(Hf). Overall, diffusion of Hf and Nb are characteristic of diffusion in bcc Zr. Surface hold-up (oxide film) at low temperatures was overcome by using ion-implanted Hf diffusion sources. The results are compared with earlier work and discussed in terms of diffusion mechanisms and the {beta}-phase transformation of commercial Zr-2.5Nb. (orig.).

  9. Perpendicular magnetic anisotropy of Co/Pt bilayers on ALD HfO2

    Science.gov (United States)

    Vermeulen, Bart F.; Wu, Jackson; Swerts, Johan; Couet, Sebastien; Linten, Dimitri; Radu, Iuliana P.; Temst, Kristiaan; Rampelberg, Geert; Detavernier, Christophe; Groeseneken, Guido; Martens, Koen

    2016-10-01

    Perpendicular Magnetic Anisotropy (PMA) is a key requirement for state of the art Magnetic Random Access Memories (MRAM). Currently, PMA has been widely reported in standard Magnetic Tunnel Junction material stacks using MgO as a dielectric. In this contribution, we present the first report of PMA at the interface with a high-κ dielectric grown by Atomic Layer Deposition, HfO2. The PMA appears after annealing a HfO2/Co/Pt/Ru stack in N2 with the Keff of 0.25 mJ/m2 as determined by Vibrating Sample Magnetometry. X-Ray Diffraction and Transmission Electron Microscopy show that the appearance of PMA coincides with interdiffusion and the epitaxial ordering of the Co/Pt bilayer. High-κ dielectrics are especially interesting for Voltage Control of Magnetic Anisotropy applications and are of potential interest for low-power MRAM and spintronics technologies.

  10. Oxygen Recovery in Hf Oxide Films Fabricated by Sputtering

    Institute of Scientific and Technical Information of China (English)

    JIANG Ran; LI Zi-Feng

    2009-01-01

    The chemical structure of ultrathin Hf oxide films (< 10 nm) fabricated by a standard sputtering method is investigated using x-ray spectroscopy and Rutherford backscattering spectroscopy. According to the experiments,oxygen species are impacted to the HfO2/Si interface during the initial sputtering, and then released back to the upper Hf02 region driven by the oxygen concentration grads. A vacuum annealing can greatly enhance this recovery process. Additionally, significant SiO2 reduction in the interface is observed after the vacuum annealing for the thick HfO2 films in our experiment. It might be an effective method to confine the interracial layer thickness by sputtering thick HfO2 in no-oxygen ambient.

  11. Crystal structure of Si-doped HfO2

    Science.gov (United States)

    Zhao, Lili; Nelson, Matthew; Aldridge, Henry; Iamsasri, Thanakorn; Fancher, Chris M.; Forrester, Jennifer S.; Nishida, Toshikazu; Moghaddam, Saeed; Jones, Jacob L.

    2014-01-01

    Si-doped HfO2 was prepared by solid state synthesis of the starting oxides. Using Rietveld refinement of high resolution X-ray diffraction patterns, a substitutional limit of Si in HfO2 was determined as less than 9 at. %. A second phase was identified as Cristobalite (SiO2) rather than HfSiO4, the latter of which would be expected from existing SiO2-HfO2 phase diagrams. Crystallographic refinement with increased Si-dopant concentration in monoclinic HfO2 shows that c/b increases, while β decreases. The spontaneous strain, which characterizes the ferroelastic distortion of the unit cell, was calculated and shown to decrease with increasing Si substitution.

  12. The (178m2)Hf Controversy

    Energy Technology Data Exchange (ETDEWEB)

    Becker, J A; Gemmell, D S; Schiffer, J P; Wilhelmy, J B

    2003-07-24

    Since its discovery in the 1960's the {sup 178m2}Hf isomer has garnered high attention from both the basic and applied communities in nuclear science. It's combination of high spin (16+), long half life (31 yrs), and high excitation energy (2.446 MeV) offer unique possibilities as an energy storage medium. Interest in the isomer was rekindled beginning in 1999 when a series of publications began to appear from a group (referred to here as the ''Texas collaboration'') primarily based at the University of Texas, Dallas [1]. They reported observations that some of the stored energy could be released (''triggered'') when the isomer was exposed to a fluence of photons in the energy range {approx}10 to {approx}60 keV. The implications of this observation are profound. Even though the claimed cross section for the process was {approx}7 orders of magnitude greater than would be predicted from the known systematics of photon absorption by nuclei in this mass range [2], such a highly efficient method for triggering the isomeric deexcitation immediately suggested applications utilizing the explosive or the controlled gradual energy release from a very compact source. The prospect of such applications has focused considerable interest on realizing the promise that is implicit in the reported observations. However, two experiments performed by a group from ANL/LANL/LLNL at the Advanced Photon Source at Argonne (the ''APS collaboration'') reported negative results for the observation of any photon-triggered deexcitation of the {sup 178m2}Hf isomer [3]. This has led to a continued controversy, where both sides have adamantly defended their observations. At this point an outsider has difficulty determining whether there is indeed a triggering effect that should be pursued energetically with substantial resources, or whether the phenomenon consists of overly optimistic interpretation of data.

  13. Approximating ambient D-region electron densities using dual-beam HF heating experiments at the high-frequency Active Auroral Research Program (HAARP)

    Science.gov (United States)

    Agrawal, Divya

    Dual-beam ELF/VLF wave generation experiments performed at the High-frequency Active Auroral Research Program (HAARP) HF transmitter in Gakona, Alaska are critically compared with the predictions of a newly developed ionospheric high frequency (HF) heating model that accounts for the simultaneous propagation and absorption of multiple HF beams. The dual-beam HF heating experiments presented herein consist of two HF beams transmitting simultaneously: one amplitude modulated (AM) HF beam modulates the conductivity of the lower ionosphere in the extremely low frequency (ELF, 30 Hz to 3 kHz) and/or very low frequency (VLF, 3 kHz to 30 kHz) band while a second HF beam broadcasts a continuous waveform (CW) signal, modifying the efficiency of ELF/VLF conductivity modulation and thereby the efficiency of ELF/VLF wave generation. Ground-based experimental observations are used together with the predictions of the theoretical model to identify the property of the received ELF/VLF wave that is most sensitive to the effects of multi-beam HF heating, and that property is determined to be the ELF/VLF signal magnitude. The dependence of the generated ELF/VLF wave magnitude on several HF transmission parameters (HF power, HF frequency, and modulation waveform) is then experimentally measured and analyzed within the context of the multi-beam HF heating model. For all cases studied, the received ELF/VLF wave magnitude as a function of transmission parameter is analyzed to identify the dependence on the ambient D-region electron density (Ne) and/or electron temperature ( Te), in turn identifying the HF transmission parameters that provide significant independent information regarding the ambient conditions of the D-region ionosphere. A theoretical analysis is performed to determine the conditions under which the effects of Ne and Te can be decoupled, and the results of this analysis are applied to identify an electron density profile that can reproduce the unusually high level of ELF

  14. Light physical activity increased body fat percentage in elderly Javanese

    Directory of Open Access Journals (Sweden)

    Fatmah Fatmah

    2016-02-01

    Full Text Available The prevalence of obesity in Indonesia is rapidly increasing, particularly in older people. Obesity is characterized by increased percentage of body fat in the form of visceral fat and non-visceral or subcutaneous fat. The aim of this study was to analyze body fat percentage (BFP and associated risk factors, i.e. type of residence (rural or urban, physical activity, gender, age, intakes of energy and fat, and socio-economic background (educational level and occupational status. This cross-sectional study was conducted on 812 older persons (517 females and 295 males from December 2007- February 2008 in the cities of Surabaya, Semarang, Yogyakarta, Wonogiri, Gunung Kidul, and Magetan subdistricts. BFP was assessed using an Omron Fat Analyzer. Nutritional intakes were collected through interviews using semi-quantitative food frequency questionnaire (FFQ. To obtain overall total energy expenditure for physical activity (PA, the energy expenditures for exercise (sports PA, daily activities, and leisure time PA were added together. The study results indicated that urban residence and light PA at age 55 years constituted risk factors for high BFP. Light PA at 55 years of age was the most influential risk factor, since it was 4.3 times greater than vigorous PA at the same age (OR=4.3; 95% Confidence interval 2.6-7.1 It is recommended to implement nutritional counseling about adequate intakes for increased PA in all age groups (adolescents, adults, older persons, particularly in urban areas with their greater risk of high BFP.

  15. Ferroelectricity-modulated resistive switching in Pt/Si:HfO2/HfO2-x /Pt memory

    Science.gov (United States)

    Ran, Jiang; Xianghao, Du; Zuyin, Han

    2016-08-01

    It is investigated for the effect of a ferroelectric Si:HfO2 thin film on the resistive switching in a stacked Pt/Si:HfO2/highly-oxygen-deficient HfO2-x /Pt structure. Improved resistance performance was observed. It was concluded that the observed resistive switching behavior was related to the modulation of the width and height of a depletion barrier in the HfO2-x layer, which was caused by the Si:HfO2 ferroelectric polarization field effect. Reliable switching reproducibility and long data retention were observed in these memory cells, suggesting their great potential in non-volatile memories applications with full compatibility and simplicity. Project supported by the National Natural Science Foundation of China (No. 11374182), the Natural Science Foundation of Shandong Province (No. ZR2012FQ012), and the Jinan Independent Innovation Projects of Universities (No. 201303019).

  16. Wideband HF Channel Prober: System Description.

    Science.gov (United States)

    1983-03-09

    results in roughly equal power. Figure 48 shows output power vs frequency for a sin- gle power amplifier operating into a dummy load in both the Sounder and...eliminate time sidelobes of the ground wave, which would otherwise clutter the display. The iono- sonde format provides the frequency-delay

  17. Finishing and Commissioning the New Arecibo HF Facility

    Science.gov (United States)

    Sulzer, M. P.; Gonzalez, S. A.

    2011-12-01

    The imminent completion of the major tasks in the construction of the New Arecibo HF facility means that we must verify that the components are working as intended. The antenna system and the transmitters must be separately commissioned before they can be connected together so that we an be sure it will provide 83 dbW at 8.175 MHz, and 80 dbW at 5.1 MHz. The antenna system will be ready for initial testing in September. It Illuminates the 305 meter dish using dipoles near the surface of the dish transmitting upward to a wire mesh sub-reflector. There are three crossed dipoles for each of the two frequencies. The dipoles are supported on towers mounted on concrete pads underneath the dish. Each dipole element is connected to a transmitter through a three inch coax line. The tower foundations are nearly complete, and the towers will be erected in early September, and we expect to have at least one crossed dipole in place for initial testing by the end of September. We will need to make some measurements on the antenna system to ensure that it meets our requirements. One requirement is to match the antenna impedance to the transmission line and the transmitter closely enough to meet the transmitter specifications, the closer, the better. We have additional requirements; for example, it is necessary for efficient use of the facility that the polarization be close to circular. In most experiments, we want O mode excitation. If we were to transmit linear only half the power would reach the reflection height. The symmetry of the system assures that most of the conditions for achieving accurate circular polarization are met, but one condition is not: that exciting the transmitters driving the orthogonal elements at 90 degrees assures 90 degree separation in the corresponding antenna currents. One of the dipoles of each pair points toward the center of the array. If we think of the three crossed dipoles as consisting of a reference and two that are excited relative to it

  18. Noise Filter Studies for CMS Forward Hadron Calorimeter (HF) Between Old and New PMT's Using Data in 2012

    CERN Document Server

    Dumanoglu, Isa; Gurpinar, Emine; Kunori, Shuichi; Lezki, Samet; Tali, Bayram

    2016-01-01

    During the data taking before 2012 some abnormal events which have higher signals than expected were observed. Most of these were due to muons. When a muon hits the PMT glass window it creates a huge signal. To eliminate this kind of events 24 old HF PMTs (Hamamatsu R7525) in HF Minus at iphi 43 (corresponds to one sector) were replaced with new multi anode PMTs (Hamamatsu multi anode R7600) which have thin glass windows. These new PMTs were installed and tested in H2 test beam area in 2009 [1]. To check whether these new PMTs perform better than the old ones data taken in 2012 were analyzed using various predefined noise filters. Noisy rechits percentage was found to be around 6-7 \\% for the new PMTs while it varies between 29-66 \\% for the old PMTs for various trigger selections and for HFLongShortFilter after an energy cut of 500GeV [2].

  19. Budgetary Approach to Project Management by Percentage of Completion Method

    Directory of Open Access Journals (Sweden)

    Leszek Borowiec

    2010-06-01

    Full Text Available Efficient and effective project management process is made possible by the use of methods and techniques of project management. The aim of this paper is to present the problems of project management by using Percentage of Completion method. The research material was gathered based on the experience in implementing this method by the Johnson Controls International Company. The article attempts to demonstrate the validity of the thesis that the POC project management method, allows for effective implementation and monitoring of the project and thus is an effective tool in the managing of companies which exploit the budgetary approach. The study presents planning process of basic parameters affecting the effectiveness of the project (such as costs, revenue, margin and characterized how the primary measurements used to evaluate it. The present theme is illustrating by numerous examples for showing the essence of the raised problems and the results are presenting by using descriptive methods, graphical and tabular.

  20. Percentage of migration as indicator of femoral head position

    Energy Technology Data Exchange (ETDEWEB)

    Ekloef, O.; Ringertz, H.; Samuelsson, L.

    In childhood subluxation of one or both hips may develop rather insidiously. For lack of generally accepted objective methods of assessment, ambiguous interpretations of findings in serial examinations are common. Many subluxations are overlooked during the early stages. In order to overcome such disadvantages, determination of the percentage of migration seems to be a reasonably easy and reliable technique facilitating evaluation of impending dislocation. This investigation was carried out in order to estabilsh norms applicable to patients in the pediatric age interval. The 98th percentile of migration increases with age from 16% in patients < 4 years of age to 24% in patients greater than or equal to 12 years. Higher figures represent subluxation. If the migration exceeds 80% a manifest luxation is present. A difference in migration between the two hips larger than 12% indicates abnormality calling for clinical and radiologic follow-up.

  1. Large ionospheric disturbances produced by the HAARP HF facility

    Science.gov (United States)

    Bernhardt, Paul A.; Siefring, Carl L.; Briczinski, Stanley J.; McCarrick, Mike; Michell, Robert G.

    2016-07-01

    The enormous transmitter power, fully programmable antenna array, and agile frequency generation of the High Frequency Active Auroral Research Program (HAARP) facility in Alaska have allowed the production of unprecedented disturbances in the ionosphere. Using both pencil beams and conical (or twisted) beam transmissions, artificial ionization clouds have been generated near the second, third, fourth, and sixth harmonics of the electron gyrofrequency. The conical beam has been used to sustain these clouds for up to 5 h as opposed to less than 30 min durations produced using pencil beams. The largest density plasma clouds have been produced at the highest harmonic transmissions. Satellite radio transmissions at 253 MHz from the National Research Laboratory TACSat4 communications experiment have been severely disturbed by propagating through artificial plasma regions. The scintillation levels for UHF waves passing through artificial ionization clouds from HAARP are typically 16 dB. This is much larger than previously reported scintillations at other HF facilities which have been limited to 3 dB or less. The goals of future HAARP experiments should be to build on these discoveries to sustain plasma densities larger than that of the background ionosphere for use as ionospheric reflectors of radio signals.

  2. HF dissociation in water clusters by computer simulations

    OpenAIRE

    Elena, Alin Marin

    2013-01-01

    We perform Restrained hybrid Monte Carlo simulations to compute the equilibrium constant of the dissociation reaction of HF in HF(H2O)7. We find that, like in the bulk, hydrofluoric acid, is a weak acid also in the cubic HF(H2O)7 cluster, and that its acidity is higher at lower T. This latter phenomenon has a (vibrational) entropic origin, namely it is due to the reduction of the (negative) T∆S contribution to the variation of free energy between the reactant and product. We found also ...

  3. Multipath Separation-Direction of Arrival (MS-DOA) with Genetic Search Algorithm for HF channels

    Science.gov (United States)

    Arikan, Feza; Koroglu, Ozan; Fidan, Serdar; Arikan, Orhan; Guldogan, Mehmet B.

    2009-09-01

    Direction-of-Arrival (DOA) defines the estimation of arrival angles of an electromagnetic wave impinging on a set of sensors. For dispersive and time-varying HF channels, where the propagating wave also suffers from the multipath phenomena, estimation of DOA is a very challenging problem. Multipath Separation-Direction of Arrival (MS-DOA), that is developed to estimate both the arrival angles in elevation and azimuth and the incoming signals at the output of the reference antenna with very high accuracy, proves itself as a strong alternative in DOA estimation for HF channels. In MS-DOA, a linear system of equations is formed using the coefficients of the basis vector for the array output vector, the incoming signal vector and the array manifold. The angles of arrival in elevation and azimuth are obtained as the maximizers of the sum of the magnitude squares of the projection of the signal coefficients on the column space of the array manifold. In this study, alternative Genetic Search Algorithms (GA) for the maximizers of the projection sum are investigated using simulated and experimental ionospheric channel data. It is observed that GA combined with MS-DOA is a powerful alternative in online DOA estimation and can be further developed according to the channel characteristics of a specific HF link.

  4. Stimulated Electromagnetic Emission Indicator of Glow Plasma Discharges from Ionospheric HF Wave Transmissions with HAARP

    Science.gov (United States)

    Bernhardt, P. A.; Scales, W.; Briczinski, S. J.; Fu, H.; Mahmoudian, A.; Samimi, A.

    2012-12-01

    High power radio waves resonantly interact with to accelerate electrons for production of artificial aurora and plasma clouds. These plasma clouds are formed when the HF frequency is tuned near a harmonic of the electron cyclotron frequency. At a narrow band resonance, large electrostatic fields are produced below the F-layer and the neutral atmosphere breaks down with a glow plasma discharge. The conditions for this resonance are given by matching the pump wave frequency and wave-number with the sum of daughter frequencies and wave-numbers for several plasma modes. The most likely plasma mode that accelerates the electrons is the electron Bernstein wave in conjunction with an ion acoustic wave. Both upper hybrid and whistler mode waves are also possible sources of electron acceleration. To determine the plasma process for electron acceleration, stimulated electromagnetic emissions are measured using ground receivers in a north-south chain from the HAARP site. Recent observations have shown that broad band spectral lines downshifted from the HF pump frequency are observed when artificial plasma clouds are formed. For HF transmissions are the 2nd, 3rd, and 4th gyro harmonic, the downshifted indicators are found 500 Hz, 20 kHz, and 140 kHz, respectively, from the pump frequency. This Indicator Mode (IM) anticipates that a plasma layer will be formed before it is recorded with an ionosonde or optical imager.

  5. Upper atmospheric effects of the hf active auroral research program ionospheric research instrument (HAARP IRI)

    Energy Technology Data Exchange (ETDEWEB)

    Eccles, V.; Armstrong, R.

    1993-05-01

    The earth's ozone layer occurs in the stratosphere, primarily between 10 and 30 miles altitude. The amount of ozone, O3, present is the result of a balance between production and destruction processes. Experiments have shown that natural processes such as auroras create molecules that destroy O. One family of such molecules is called odd nitrogen of which nitric oxide (NO) is an example. Because the HAARP (HF Active Auroral Research Program) facility is designed to mimic and investigate certain natural processes, a study of possible effects of HAARP on the ozone layer was conducted. The study used a detailed model of the thermal and chemical effects of the high power HF beam, which interacts with free electrons in the upper atmosphere above 50 miles altitude. It was found only a small fraction of the beam energy goes into the production of odd nitrogen molecules, whereas odd nitrogen is efficiently produced by auroras. Since the total energy emitted by HAARP in the year is some 200,000 times less than the energy deposited in the upper atmosphere by auroras, the study demonstrates that HAARP HF beam experiments will cause no measurable depletion of the earth's ozone layer.... Ozone, Ozone depletion, Ozone layer, Odd nitrogen, Nitric oxide, HAARP Emitter characteristics.

  6. Detection and Analysis of Partial Reflections of HF Waves from the Lower Ionosphere

    Science.gov (United States)

    Erdman, A.; Moore, R. C.

    2016-12-01

    On the afternoon of August 27, 2011, the western half of the High Frequency Active Auroral Research Program's (HAARP's) HF transmitter repeatedly broadcast a low-power (1 kW/Tx), 4.5-MHz, X-mode polarized, 10 microsecond pulse. The HF beam was directed vertically, and the inter-pulse period was 20 milliseconds. HF observations were performed at Oasis (62° 23' 30" N, 145° 9' 03" W) using two crossed 90-foot folded dipoles. Observations clearly indicate the detection of a ground wave and multiple reflections from different sources at F-region altitudes, which is consistent with digisonde measurements at 4.5 MHz. Additional reflections were detected at a virtual altitude of 90-110 km, and we interpret these reflections as partial reflections from the rapid conductivity change at the base of the ionosphere. We compare these observations with the predictions of a new finite-difference time-domain (FDTD) plasma model. The model is a one-dimensional, second-order accurate, cold plasma FDTD model of the ionosphere extending from ground through the lower F-region. The model accounts for a spatially varying plasma frequency, cyclotron frequency, and electron-neutral collision frequency. We discuss the possibility to analyze partial reflections from the base of the ionosphere as a function of frequency to characterize the reflecting plasma.

  7. Process Simulation Analysis of HF Stripping

    Directory of Open Access Journals (Sweden)

    Thaer A. Abdulla

    2013-05-01

    Full Text Available    HYSYS process simulator is used for the analysis of existing HF stripping column in LAB plant (Arab Detergent Company, Baiji-Iraq. Simulated column performance and profiles curves are constructed. The variables considered are the thermodynamic model option, bottom temperature, feed temperature, and column profiles for the temperature, vapor flow rate, liquid flow rate and composition. The five thermodynamic models options used (Margules, UNIQUAC, van laar, Antoine, and Zudkevitch-Joffee, affecting the results within (0.1-58% variation for the most cases.        The simulated results show that about 4% of paraffin (C10 & C11 presents at the top stream, which may cause a problem in the LAB production plant. The major variations were noticed for the total top vapor flow rate with bottom temperature and with feed composition. The column profiles maintain fairly constants from tray 5 to tray 18. The study gives evidence about a successful simulation with HYSYS because the results correspond with the real plant operation data.

  8. The (178m2) Hf Controversy

    CERN Document Server

    Becker, J A; Schiffer, J P; Wilhelmy, J

    2003-01-01

    Since its discovery in the 1960's the sup 1 sup 7 sup 8 sup m sup 2 Hf isomer has garnered high attention from both the basic and applied communities in nuclear science. It's combination of high spin (16+), long half life (31 yrs), and high excitation energy (2.446 MeV) offer unique possibilities as an energy storage medium. Interest in the isomer was rekindled beginning in 1999 when a series of publications began to appear from a group (referred to here as the ''Texas collaboration'') primarily based at the University of Texas, Dallas [1]. They reported observations that some of the stored energy could be released (''triggered'') when the isomer was exposed to a fluence of photons in the energy range approx 10 to approx 60 keV. The implications of this observation are profound. Even though the claimed cross section for the process was approx 7 orders of magnitude greater than would be predicted from the known systematics of photon absorption by nuclei in this mass range [2], such a highly efficient method fo...

  9. Grindability of cast Ti-Hf alloys.

    Science.gov (United States)

    Kikuchi, Masafumi; Takahashi, Masatoshi; Sato, Hideki; Okuno, Osamu; Nunn, Martha E; Okabe, Toru

    2006-04-01

    As part of our systematic studies characterizing the properties of titanium alloys, we investigated the grindability of a series of cast Ti-Hf alloys. Alloy buttons with hafnium concentrations up to 40 mass% were made using an argon-arc melting furnace. Each button was cast into a magnesia-based mold using a dental titanium casting machine; three specimens were made for each metal. Prior to testing, the hardened surface layer was removed. The specimens were ground at five different speeds for 1 min at 0.98 N using a carborundum wheel on an electric dental handpiece. Grindability was evaluated as the volume of metal removed per minute (grinding rate) and the volume ratio of metal removed compared to the wheel material lost (grinding ratio). The data were analyzed using ANOVA. A trend of increasing grindability was found with increasing amounts of hafnium, although there was no statistical difference in the grindability with increasing hafnium contents. We also found that hafnium may be used to harden or strengthen titanium without deteriorating the grindability.

  10. Characterizing the surface circulation in the Ebro Delta using a HF radar data-model approach

    Science.gov (United States)

    Lorente Jimenez, Pablo; Piedracoba Varela, Silvia; Soto-Navarro, Javier; Garcia-Sotillo, Marcos; Alvarez Fanjul, Enrique

    2016-04-01

    One year-long (2014) quality-controlled current observations from a CODAR SeaSonde High Frequency (HF) radar network deployed in the Ebro Delta (northwestern Mediterranean) were combined with operational products provided by a regional ocean forecasting system named IBI (Iberia-Biscay-Ireland) in order to comprehensively portray the ocean state and its variability. First, accurate HF radar data were used as benchmark for the rigorous validation of IBI performance by means of the computation of skill metrics and quality indicators. The analysis of the monthly averaged current maps for 2014 showed that IBI properly captured the prevailing dynamic features of the coastal circulation observed by the HF radar, according to the resemblance of circulation patterns and the eddy kinetic energy spatial distribution. The model skill assessment was completed with an exploration of dominant modes of variability both in time and space. The EOF analysis confirmed that the modeled surface current field evolved in space and time according to three significantly dominant modes of variability which accounted for the 49.2% of the total variance, in close agreement with the results obtained for the HF radar (46.1%). The response of the subtidal surface current field to prevalent wind regimes in the study area was examined in terms of induced circulation structures by performing a conditional averaging approach. This data-model synergistic approach has proved to be valid to operationally monitor and describe the complex coastal circulation in Ebro Delta despite the observed model drawbacks in terms of reduced energy content in surface currents and some inaccuracies in the wind-driven low frequency response. This integrated methodology constitutes a powerful tool for improving operational ocean forecasting systems at European level within the frame of the Copernicus Marine Environment Monitoring Service (CMEMS). It also facilitates high-stakes decision-making for coastal management and

  11. The magnetic properties of $^{\\rm 177}$Hf and $^{\\rm 180}$Hf in the strong coupling deformed model

    OpenAIRE

    Muto, S.; Stone, N. J.; Bingham, C. R.; STONE, J.R; Walker, P. M.; Audi, G.; Gaulard, C.; Köster, U.(Institut Laue-Langevin (ILL), Grenoble, France); Nikolov, J.; Nishimura,K; Ohtsubo, T.; Podolyak, Z.; Risegari, L.; Simpson, G.S.; Veskovic, M.

    2014-01-01

    This paper reports NMR measurements of the magnetic dipole moments of two high-K isomers, the 37/2$^-$, 51.4 m, 2740 keV state in $^{\\rm 177}$Hf and the 8$^-$, 5.5 h, 1142 keV state in $^{\\rm 180}$Hf by the method of on-line nuclear orientation. Also included are results on the angular distributions of gamma transitions in the decay of the $^{\\rm 177}$Hf isotope. These yield high precision E2/M1 multipole mixing ratios for transitions in bands built on the 23/2$^+$, 1.1 s, isomer at 1315 keV ...

  12. Body Fat Percentage Prediction Using Intelligent Hybrid Approaches

    Directory of Open Access Journals (Sweden)

    Yuehjen E. Shao

    2014-01-01

    Full Text Available Excess of body fat often leads to obesity. Obesity is typically associated with serious medical diseases, such as cancer, heart disease, and diabetes. Accordingly, knowing the body fat is an extremely important issue since it affects everyone’s health. Although there are several ways to measure the body fat percentage (BFP, the accurate methods are often associated with hassle and/or high costs. Traditional single-stage approaches may use certain body measurements or explanatory variables to predict the BFP. Diverging from existing approaches, this study proposes new intelligent hybrid approaches to obtain fewer explanatory variables, and the proposed forecasting models are able to effectively predict the BFP. The proposed hybrid models consist of multiple regression (MR, artificial neural network (ANN, multivariate adaptive regression splines (MARS, and support vector regression (SVR techniques. The first stage of the modeling includes the use of MR and MARS to obtain fewer but more important sets of explanatory variables. In the second stage, the remaining important variables are served as inputs for the other forecasting methods. A real dataset was used to demonstrate the development of the proposed hybrid models. The prediction results revealed that the proposed hybrid schemes outperformed the typical, single-stage forecasting models.

  13. Utility of Immature Granulocyte Percentage in Pediatric Appendicitis

    Science.gov (United States)

    Mathews, Eleanor K.; Griffin, Russell L.; Mortellaro, Vincent; Beierle, Elizabeth A.; Harmon, Carroll M.; Chen, Mike K.; Russell, Robert T.

    2014-01-01

    Background Acute appendicitis is the most common cause of abdominal surgery in children. Adjuncts are utilized to help clinicians predict acute or perforated appendicitis, which may affect treatment decisions. Automated hematologic analyzers can perform more accurate automated differentials including immature granulocyte percentages (IG%). Elevated IG% has demonstrated improved accuracy for predicting sepsis in the neonatal population than traditional immature to total neutrophil count (I/T) ratios. We intended to assess the additional discriminatory ability of IG% to traditionally assessed parameters in the differentiation between acute and perforated appendicitis. Materials and Methods We identified all patients with appendicitis from July 2012 to June 2013 by ICD-9 code. Charts were reviewed for relevant demographic, clinical, and outcome data, which were compared between acute and perforated appendicitis groups using Fischer’s exact and t-test for categorical and continuous variables, respectively. We utilized an adjusted logistic regression model utilizing clinical lab values to predict the odds of perforated appendicitis. Results 251 patients were included in the analysis. Those with perforated appendicitis had a higher white blood cell (WBC) count (p=0.0063), C-reactive protein (CRP) (pappendicitis. The c-statistic of the final model was 0.70, suggesting fair discriminatory ability in predicting perforated appendicitis. Conclusions IG% did not provide any additional benefit to elevated CRP and presence of left shift in the differentiation between acute and perforated appendicitis. PMID:24793450

  14. Volumetric combustion of torrefied biomass for large percentage biomass co-firing up to 100% fuel switch

    OpenAIRE

    Li, Jun

    2014-01-01

    The co-firing of biomass and coal plays an important role in increasing the biomass power capacity and reducing greenhouse gas (GHG) emissions. The challenges of the large percentage biomass co-firing (over 20% on energy basis) in existing pulverized coal boilers are keeping the same steam parameters and having a high boiler efficiency and a stable operating. The primary goal of this thesis is to develop a combustion concept for coal-fired boilers to enablea large percentage of biomass co-fir...

  15. 100 Days of ELF/VLF Generation via HF Heating with HAARP (Invited)

    Science.gov (United States)

    Cohen, M.; Golkowski, M.

    2013-12-01

    ELF/VLF radio waves are difficult to generate with conventional antennas. Ionospheric HF heating facilities generate ELF/VLF waves via modulated heating of the lower ionosphere. HF heating of the ionosphere changes the lower ionospheric conductivity, which in the presence of natural currents such as the auroral electrojet, creates an antenna in the sky when heating is modulated at ELF/VLF frequencies. We present a summary of nearly 100 days of ELF/VLF wave generation experiments at the 3.6 MW HAARP facility near Gakona, Alaska, and provide a baseline reference of ELF/VLF generation capabilities with HF heating. Between February 2007 and August 2008, HAARP was operated on close to 100 days for ELF/VLF wave generation experiments, at a variety of ELF/VLF frequencies, seasons and times of day. We present comprehensive statistics of generated ELF/VLF magnetic fields observed at a nearby site, in the 500-3500 Hz band. Transmissions with a specific HF beam configuration (3.25 MHz, vertical beam, amplitude modulation) are isolated so the data comparison is self-consistent, across nearly 5 million individual measurements of either a tone or a piece of a frequency-time ramp. There is a minimum in the average generation close to local midnight. It is found that generation during local nighttime is on average weaker, but more highly variable, with a small number of very strong generation periods. Signal amplitudes from day to day may vary by as much as 20-30 dB. Generation strengthens by ~5 dB during the first ~30 minutes of transmission, which may be a signature of slow electron density changes from sustained HF heating. Theoretical calculations are made to relate the amplitude observed to the power injected into the waveguide and reaching 250 km. The median power generated by HAARP and injected into the waveguide is ~0.05-0.1 W in this base-line configuration (vertical beam, 3.25 MHz, amplitude modulation), but may have generated hundreds of Watts for brief durations

  16. A thirty second isomer in {sup 171}Hf

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, P.; Billowes, J.; Cooper, T.G.; Grant, I.S.; Pearson, M.R.; Wheeler, P.D. [Schuster Laboratory, University of Manchester, M13 9PL (United Kingdom); Cochrane, E.C.A.; Cooke, J.L.; Evans, D.E.; Griffith, J.A.R.; Persson, J.R.; Richardson, D.S.; Tungate, G.; Zybert, L. [School of Physics and Space Research, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Dendooven, P.; Honkanen, A.; Huhta, M.; Oinonen, M.; Penttilae, H.; Aeystoe, J. [Accelerator Laboratory, University of Jyvaeskylae, PL 35 Jyvaeskylae SF-403 51 (Finland)

    1997-09-01

    An isomer has been detected in {sup 171}Hf with a half-life of T{sub 1/2} 29.5(9) s. The state was populated in the {sup 170}Yb({alpha},3n){sup 171m}Hf reaction at a beam energy of E{sub {alpha}} = 50 MeV in an on-line ion guide isotope separator. The isomeric {sup 171m}Hf{sup +} beam was extracted from the ion guide, mass-analysed and implanted in the surface of a microchannel-plate. The half-life of the collected activity was measured from the decay of the microchannel-plate count rate. We associate the isomer with the first excited state in {sup 171}Hf with spin 1/2{sup -} at an excitation energy of 22(2) keV. (author)

  17. HF fiber stuffing in building 186 at CERN

    CERN Multimedia

    Tiziano Camporesi

    2003-01-01

    Each of the 36 HF wedges comprise ca 12000 quartz fibers which are the active element of the calorimeter. The fibers are produced by Polymicro (USA), cleaved and bundled at KFKI, Budapest, Hungary and inserted at CERN.

  18. Near-infrared LIF spectroscopy of HfF

    CERN Document Server

    Grau, Matt; Loh, Huanqian; Sinclair, Laura C; Stutz, Russel P; Yahn, Tylser S; Cornell, Eric A

    2012-01-01

    The molecular ion HfF$^+$ is the chosen species for a JILA experiment to measure the electron electric dipole moment (eEDM). Detailed knowledge of the spectrum of HfF is crucial to prepare HfF$^+$ in a state suitable for performing an eEDM measurement\\cite{Leanhardt}. We investigated the near-infrared electronic spectrum of HfF using laser-induced fluorescence (LIF) of a supersonic molecular beam. We discovered eight unreported bands, and assign each of them unambiguously, four to vibrational bands belonging to the transition $[13.8]0.5 \\leftarrow X1.5$, and four to vibrational bands belonging to the transition $[14.2]1.5 \\leftarrow X1.5$. Additionally, we report an improved measurement of vibrational spacing of the ground state, as well as anharmonicity $\\omega_e x_e$.

  19. Theoretical Assessment of 178m2Hf De-Excitation

    Energy Technology Data Exchange (ETDEWEB)

    Hartouni, E P; Chen, M; Descalle, M A; Escher, J E; Loshak, A; Navratil, P; Ormand, W E; Pruet, J; Thompson, I J; Wang, T F

    2008-10-06

    This document contains a comprehensive literature review in support of the theoretical assessment of the {sup 178m2}Hf de-excitation, as well as a rigorous description of controlled energy release from an isomeric nuclear state.

  20. Synthesis of freestanding HfO2 nanostructures

    Directory of Open Access Journals (Sweden)

    Boyle Kayla

    2011-01-01

    Full Text Available Abstract Two new methods for synthesizing nanostructured HfO2 have been developed. The first method entails exposing HfTe2 powders to air. This simple process resulted in the formation of nanometer scale crystallites of HfO2. The second method involved a two-step heating process by which macroscopic, freestanding nanosheets of HfO2 were formed as a byproduct during the synthesis of HfTe2. These highly two-dimensional sheets had side lengths measuring up to several millimeters and were stable enough to be manipulated with tweezers and other instruments. The thickness of the sheets ranged from a few to a few hundred nanometers. The thinnest sheets appeared transparent when viewed in a scanning electron microscope. It was found that the presence of Mn enhanced the formation of HfO2 by exposure to ambient conditions and was necessary for the formation of the large scale nanosheets. These results present new routes to create freestanding nanostructured hafnium dioxide. PACS: 81.07.-b, 61.46.Hk, 68.37.Hk.

  1. The isobutylene-isobutane alkylation process in liquid HF revisited.

    Science.gov (United States)

    Esteves, P M; Araújo, C L; Horta, B A C; Alvarez, L J; Zicovich-Wilson, C M; Ramírez-Solís, A

    2005-07-07

    Details on the mechanism of HF catalyzed isobutylene-isobutane alkylation were investigated. On the basis of available experimental data and high-level quantum chemical calculations, a detailed reaction mechanism is proposed taking into account solvation effects of the medium. On the basis of our computational results, we explain why the density of the liquid media and stirring rates are the most important parameters to achieve maximum yield of alkylate, in agreement with experimental findings. The ab initio Car-Parrinello molecular dynamics calculations show that isobutylene is irreversibly protonated in the liquid HF medium at higher densities, leading to the ion pair formation, which is shown to be a minimum on the potential energy surface after optimization using periodic boundary conditions. The HF medium solvates preferentially the fluoride anion, which is found as solvated [FHF](-) or solvated F(-.)(HF)(3). On the other hand, the tert-butyl cation is weakly solvated, where the closest HF molecules appear at a distance of about 2.9 Angstrom with the fluorine termination of an HF chain.

  2. [Sedentary lifestyle: physical activity duration versus percentage of energy expenditure].

    Science.gov (United States)

    Cabrera de León, Antonio; Rodríguez-Pérez, María del C; Rodríguez-Benjumeda, Luis M; Anía-Lafuente, Basilio; Brito-Díaz, Buenaventura; Muros de Fuentes, Mercedes; Almeida-González, Delia; Batista-Medina, Marta; Aguirre-Jaime, Armando

    2007-03-01

    To compare different definitions of a sedentary lifestyle and to determine which is the most appropriate for demonstrating its relationship with the metabolic syndrome and other cardiovascular risk factors. A cross-sectional study of 5814 individuals was carried out. Comparisons were made between two definitions of a sedentary lifestyle: one based on active energy expenditure being less than 10% of total energy expenditure, and the other, on performing less than 25-30 minutes of physical activity per day. Reported levels of physical activity, anthropometric measurements, and biochemical markers of cardiovascular risk were recorded. The associations between a sedentary lifestyle and metabolic syndrome and other risk factors were adjusted for gender, age and tobacco use. The prevalence of a sedentary lifestyle was higher in women (70%) than in men (45-60%, according to the definition used). The definitions based on physical activity duration and on energy expenditure were equally useful: there were direct associations between a sedentary lifestyle and metabolic syndrome, body mass index, abdominal and pelvic circumferences, systolic blood pressure, heart rate, apolipoprotein B, and triglycerides, and inverse associations with high-density lipoprotein cholesterol and paraoxonase activity, which demonstrated the greatest percentage difference between sedentary and active individuals. An incidental finding was that both definitions of a sedentary lifestyle were more strongly associated with the metabolic syndrome as defined by International Diabetes Federation criteria than by Adult Treatment Panel III criteria. Given that it is relatively easy to determine whether a patient performs less than 25 minutes of physical activity per day, use of this definition of a sedentary lifestyle is recommended for clinical practice. The serum paraoxonase activity level could provide a useful marker for studying sedentary lifestyles.

  3. Hf impurity and defect interactions in helium-implanted NiHf

    Energy Technology Data Exchange (ETDEWEB)

    Govindaraj, R. E-mail: govind@igcar.ernet.in; Gopinathan, K.P.; Viswanathan, B

    2001-07-01

    TDPAC measurements on the reference and untreated sample indicate a loss in anisotropy which is attributed mainly to the association of probe atoms with defects produced by (n,{gamma}) reactions with isotopes of Ni and experiencing combined magnetic and quadrupole interactions of comparable strengths. Evolution of defect free and substitutional fraction of probe atoms experiencing Larmor frequency characteristic of Ni matrix has been studied as a function of isochronal annealing temperature in helium free {alpha}-irradiated and homogeneously helium-implanted samples. No defect associated Larmor precession frequency and/or quadrupole frequency could be deduced in these uncorrelated damage studies. Comparison of recovery stages in {alpha}-irradiated and helium-implanted samples indicates the binding of helium associated defects by Hf impurities. Segregation of Hf atoms is observed in the helium free {alpha}-irradiated sample for annealing treatment at 973 K, while no such effect is observed in the helium-implanted sample for isochronal annealing treatments up to 1273 K.

  4. Reconciliation of the excess 176Hf conundrum in meteorites: Recent disturbances of the Lu-Hf and Sm-Nd isotope systematics

    Science.gov (United States)

    Bast, Rebecca; Scherer, Erik E.; Sprung, Peter; Mezger, Klaus; Fischer-Gödde, Mario; Taetz, Stephan; Böhnke, Mischa; Schmid-Beurmann, Hinrich; Münker, Carsten; Kleine, Thorsten; Srinivasan, Gopalan

    2017-09-01

    The long-lived 176Lu-176Hf and 147Sm-143Nd radioisotope systems are commonly used chronometers, but when applied to meteorites, they can reveal disturbances. Specifically, Lu-Hf isochrons commonly yield dates up to ∼300 Myr older than the solar system and varying initial 176Hf/177Hf values. We investigated this problem by attempting to construct mineral and whole rock isochrons for eucrites and angrites. Meteorites from different parent bodies exhibit similar disturbance features suggesting that a common process is responsible. Minerals scatter away from isochron regressions for both meteorite classes, with low-Hf phases such as plagioclase and olivine typically being most displaced above (or left of) reference isochrons. Relatively Hf-rich pyroxene is less disturbed but still to the point of steepening Lu-Hf errorchrons. Using our Lu-Hf and Sm-Nd data, we tested various Hf and Lu redistribution scenarios and found that decoupling of Lu/Hf from 176Hf/177Hf must postdate the accumulation of significant radiogenic 176Hf. Therefore early irradiation or diffusion cannot explain the excess 176Hf. Instead, disturbed meteorite isochrons are more likely caused by terrestrial weathering, contamination, or common laboratory procedures. The partial dissolution of phosphate minerals may predominantly remove rare earth elements including Lu, leaving relatively immobile and radiogenic Hf behind. Robust Lu-Hf (and improved Sm-Nd) meteorite geochronology will require the development of chemical or physical methods for removing unsupported radiogenic Hf and silicate-hosted terrestrial contaminants without disturbing parent-daughter ratios.

  5. Tracking magmatic processes through Zr/Hf ratios in rocks and Hf and Ti zoning in zircons: An example from the Spirit Mountain batholith, Nevada

    Science.gov (United States)

    Lowery, Claiborne L.E.; Miller, C.F.; Walker, B.A.; Wooden, J.L.; Mazdab, F.K.; Bea, F.

    2006-01-01

    Zirconium and Hf are nearly identical geochemically, and therefore most of the crust maintains near-chondritic Zr/Hf ratios of ???35-40. By contrast, many high-silica rhyolites and granites have anomalously low Zr/Hf (15-30). As zircon is the primary reservoir for both Zr and Hf and preferentially incorporates Zr, crystallization of zircon controls Zr/ Hf, imprinting low Zr/Hf on coexisting melt. Thus, low Zr/Hf is a unique fingerprint of effective magmatic fractionation in the crust. Age and compositional zonation in zircons themselves provide a record of the thermal and compositional histories of magmatic systems. High Hf (low Zr/ Hf) in zircon zones demonstrates growth from fractionated melt, and Ti provides an estimate of temperature of crystallization (TTiZ) (Watson and Harrison, 2005). Whole-rock Zr/Hf and zircon zonation in the Spirit Mountain batholith, Nevada, document repeated fractionation and thermal fluctuations. Ratios of Zr/Hf are ???30-40 for cumulates and 18-30 for high-SiO2 granites. In zircons, Hf (and U) are inversely correlated with Ti, and concentrations indicate large fluctuations in melt composition and TTiZ (>100??C) for individual zircons. Such variations are consistent with field relations and ion-probe zircon geochronology that indicate a >1 million year history of repeated replenishment, fractionation, and extraction of melt from crystal mush to form the low Zr/Hf high-SiO2 zone. ?? 2006 The Mineralogical Society.

  6. Determination of isothermal section of Ni-Re-Hf ternary system at 1173 K

    Institute of Scientific and Technical Information of China (English)

    王日初; 柳春雷; 金展鹏

    2002-01-01

    The phase equilibriua in the Ni-Re-Hf ternary system at 1173K were investigated by means of diffusion triple technique and electron microprobe analysis(EMPA). The experimental results indicate that two ternary intermetallics (α and β) and five binary intermetallics (Ni3Hf, Ni10Hf7, Ni11Hf9, NiHf and NiHf2) exist in the Ni-Re-Hf system at 1173 K. A tentative isothermal section of this system at 1173 K was constructed on the basis of experimental results. The isothermal section consists of nine three-phase regions, five of which are supported by the experimental data.

  7. Combined U-Pb and Lu-Hf isotope analyses by laser ablation MC-ICP-MS: methodology and applications

    Directory of Open Access Journals (Sweden)

    Massimo Matteini

    2010-06-01

    Full Text Available The Lutetium-Hafnium isotopic system represents one of the most innovative and powerful tools for geochronology and isotopic studies. Combined U-Pb and Lu-Hf in situ analyses on zircon by LA-MC-ICP-MS permit to characterize isotopically the host magma from which it crystallized furnishing significant information for sediment provenance and crustal evolution studies. In this paper e describe the Lu-Hf systematic by LA-MC-ICP-MS developed in the laboratory of Geochronology of the University of Brasilia and report the results obtained by repeated analyses of 176Hf/177Hf isotopic ratio of three zircon standards: GJ-1 = 0.282022 ± 11 (n=56, Temora 2 = 0.282693 ± 14 (n=25 and UQZ = 0.282127 ± 33 (n=11. The 176Hf/177Hf ratio (0.282352 ± 22, n=14 of gem quality zircon used as in-house standard have been also characterized. As a geological application, we analyzed two complex zircons selected from a migmatitic rocks from the Borborema Province, NE Brazil. On the basis of U-Pb and Lu-Hf data, two main crystallization events have been identified in both studied zircons. An older event at ca. 2.05 Ga recognized in the inherited cores represents a well-characterized paleoproterozoic magmatic event that affected the whole Borborema Province. A second crystallization event at ~ 575 Ma, recognized at the rims, represents a Neoproterozoic (Brazilian high grade metamorphic-magmatic event.O sistema isotópico Lutécio-Hafnio representa uma das ferramentas mais recentes e poderosas para estudos isotópicos e geocronológicos. Análises combinadas in situ de U-Pb e Lu-Hf sobre zircão pelo LA-MC-ICP-MS permitem caracterizar iso-topicamente o magma onde ele cristalizou, fornecendo valiosas informações para estudos de proveniência de sedimento e de evolução crustal. Nesse trabalho descrevemos a sistemática de Lu-Hf pelo LA-MC-ICP-MS implantada no laboratório de Geocronologia da Universidade de Brasília e reportamos os resultados obtidos de repetidas an

  8. Heterogeneity of variances for carcass traits by percentage Brahman inheritance.

    Science.gov (United States)

    Crews, D H; Franke, D E

    1998-07-01

    Heterogeneity of carcass trait variances due to level of Brahman inheritance was investigated using records from straightbred and crossbred steers produced from 1970 to 1988 (n = 1,530). Angus, Brahman, Charolais, and Hereford sires were mated to straightbred and crossbred cows to produce straightbred, F1, back-cross, three-breed cross, and two-, three-, and four-breed rotational crossbred steers in four non-overlapping generations. At weaning (mean age = 220 d), steers were randomly assigned within breed group directly to the feedlot for 200 d, or to a backgrounding and stocker phase before feeding. Stocker steers were fed from 70 to 100 d in generations 1 and 2 and from 60 to 120 d in generations 3 and 4. Carcass traits included hot carcass weight, subcutaneous fat thickness and longissimus muscle area at the 12-13th rib interface, carcass weight-adjusted longissimus muscle area, USDA yield grade, estimated total lean yield, marbling score, and Warner-Bratzler shear force. Steers were classified as either high Brahman (50 to 100% Brahman), moderate Brahman (25 to 49% Brahman), or low Brahman (0 to 24% Brahman) inheritance. Two types of animal models were fit with regard to level of Brahman inheritance. One model assumed similar variances between pairs of Brahman inheritance groups, and the second model assumed different variances between pairs of Brahman inheritance groups. Fixed sources of variation in both models included direct and maternal additive and nonadditive breed effects, year of birth, and slaughter age. Variances were estimated using derivative free REML procedures. Likelihood ratio tests were used to compare models. The model accounting for heterogeneous variances had a greater likelihood (P carcass weight, longissimus muscle area, weight-adjusted longissimus muscle area, total lean yield, and Warner-Bratzler shear force, indicating improved fit with percentage Brahman inheritance considered as a source of heterogeneity of variance. Genetic

  9. Spallation and fission products in the (p+{sup 179}Hf) and (p+{sup nat}Hf) reactions

    Energy Technology Data Exchange (ETDEWEB)

    Karamian, S.A. [Joint Institute for Nuclear Research, Moscow Region, Dubna 141980 (Russian Federation); Ur, C.A. [Horia Hulubei National Institute of Physics and Nuclear Engineering, P.O. Box MG-6, Bucharest 077125 (Romania); Induced Gamma Emission Foundation, P.O. Box 34-81, Bucharest 010044 (Romania)], E-mail: ur@pd.infn.it; Adam, J. [Joint Institute for Nuclear Research, Moscow Region, Dubna 141980 (Russian Federation); Institute of Nuclear Physics, Rez, Prague CZ-25068 (Czech Republic); Kalinnikov, V.G.; Lebedev, N.A.; Vostokin, G.K. [Joint Institute for Nuclear Research, Moscow Region, Dubna 141980 (Russian Federation); Collins, C.B. [Center for Quantum Electronics, University of Texas at Dallas, Richardson, TX 75083 (United States); Popescu, I.I. [Induced Gamma Emission Foundation, P.O. Box 34-81, Bucharest 010044 (Romania)

    2009-03-01

    Production of Hf and Lu high-spin isomers has been experimentally studied in spallation reactions induced by intermediate energy protons. Targets of enriched {sup 179}Hf (91%) and {sup nat}Hf were bombarded with protons of energy in the range from 90 to 650 MeV provided by the internal beam of the Dubna Phasotron synchrocyclotron. The activation yields of the reaction products were measured by using the {gamma}-ray spectroscopy and radiochemistry methods. The production cross-sections obtained for the {sup 179m2}Hf, {sup 178m2}Hf and {sup 177m}Lu isomers are similar to the previously measured values from the spallation of Ta, Re and W targets. Therefore, the reactions involving emission of only a few nucleons, like (p,p'), (p,p'n) and (p,2pn), can transfer high enough angular momentum to the final residual nuclei with reasonable large cross-sections. A significant gain in the isomeric yields was obtained when enriched {sup 179}Hf targets were used. The mass distribution of the residual nuclei was measured over a wide range of masses and the fission-to-spallation ratio could be deduced as a function of the projectile energy. Features of the reaction mechanism are briefly discussed.

  10. Antimicrobial Resistance Percentages of Salmonella and Shigella in Seafood Imported to Jordan: Higher Percentages and More Diverse Profiles in Shigella.

    Science.gov (United States)

    Obaidat, Mohammad M; Bani Salman, Alaa E

    2017-03-01

    This study determined the prevalence and antimicrobial resistance of human-specific ( Shigella spp.) and zoonotic ( Salmonella enterica ) foodborne pathogens in internationally traded seafood. Sixty-four Salmonella and 61 Shigella isolates were obtained from 330 imported fresh fish samples from Egypt, Yemen, and India. The pathogens were isolated on selective media, confirmed by PCR, and tested for antimicrobial resistance. Approximately 79 and 98% of the Salmonella and Shigella isolates, respectively, exhibited resistance to at least one antimicrobial, and 8 and 49% exhibited multidrug resistance (resistance to three or more antimicrobial classes). Generally, Salmonella exhibited high resistance to amoxicillin-clavulanic acid, cephalothin, streptomycin, and ampicillin; very low resistance to kanamycin, tetracycline, gentamicin, chloramphenicol, nalidixic acid, sulfamethoxazole-trimethoprim, and ciprofloxacin; and no resistance to ceftriaxone. Meanwhile, Shigella spp. exhibited high resistance to tetracycline, amoxicillin-clavulanic acid, cephalothin, streptomycin, and ampicillin; low resistance to kanamycin, nalidixic acid, sulfamethoxazole-trimethoprim, and ceftriaxone; and very low resistance to gentamicin and ciprofloxacin. Salmonella isolates exhibited 14 resistance profiles, Shigella isolates 42. This study is novel in showing that a human-specific pathogen has higher antimicrobial resistance percentages and more diverse profiles than a zoonotic pathogen. Thus, the impact of antimicrobial use in humans is as significant as, if not more significant than, it is in animals in spreading antibiotic resistance through food. This study also demonstrates that locally derived antimicrobial resistance can spread and pose a public health risk worldwide through seafood trade and that high resistance would make a possible outbreak difficult to control. So, capacity building and monitoring harvest water areas are encouraged in fish producing countries.

  11. Hf-Nd isotope and trace element constraints on subduction inputs at island arcs: Limitations of Hf anomalies as sediment input indicators

    Science.gov (United States)

    Handley, Heather K.; Turner, Simon; Macpherson, Colin G.; Gertisser, Ralf; Davidson, Jon P.

    2011-04-01

    New Nd-Hf isotope and trace element data for Javanese volcanoes are combined with recently published data to place constraints on subduction inputs at the Sunda arc in Indonesia and assess the value of Hf anomalies (expressed as Hf/Hf* and Sm/Hf ratios) as tracers of such inputs. Hf anomaly does not correlate with Hf isotope ratio in Javanese lavas, however, Hf/Hf* and Sm/Hf ratios do correlate with SiO 2. Contrary to previous work, we show that Hf anomaly variation may be controlled by fractionation of clinopyroxene and/or amphibole during magmatic differentiation and does not represent the magnitude or type of subduction input in some arcs. Correlation of Sm/Hf with indices of differentiation for other arcs (e.g., Vanuatu, New Britain, and Mariana) suggests that differentiation control on Sm/Hf ratios in volcanic arc rocks may be a relatively common phenomenon. This study corroborates the use of Nd-Hf isotope co-variations in arc volcanic rocks to ascertain subduction input characteristics. The trajectories of regional volcano groups (East, Central and West Java) in Nd-Hf isotope space reveal heterogeneity in the subducted sediment input along Java, which reflects present-day spatial variations in sediment compositions on the down-going plate in the Java Trench. The high Sm/Hf ratio required in the sediment end-member for some Javanese basalts suggests that partial melting of subducted sediment occurs in the presence of residual zircon, and is inconsistent with residual monazite or allanite.

  12. Investigation into the problem of characterization of the HF ionospheric fluctuating channel of propagation: construction of a physically based HF channel simulator

    Directory of Open Access Journals (Sweden)

    H. J. Strangeways

    2004-06-01

    Full Text Available A wideband HF simulator has been constructed that is based on a detailed physical model. It can generate an output giving a time realization of the HF wideband channel for any HF carrier frequency and bandwidth and for any given transmitter receiver path, time of day, month and year and for any solar activity/geomagnetic conditions. To accomplish this, a comprehensive solution has been obtained to the problem of HF wave propagation for the most general case of a 3D inhomogeneous ionosphere with time-varying electron density fluctuations. The solution is based on the complex phase method (Rytov s method, which has been extended to the case of an inhomogeneous medium and a point source of the field. Results of simulation obtained according to the technique developed have been presented, calculated for a single-hop path 1000 km long oriented to the south from St. Petersburg and including a horizontal electron density gradient present in the IRI model used as the basis of the ionosphere model. The fluctuations of the ionospheric electron density were characterized by an inverse power law anisotropic spatial spectrum. For this model, the random walk of the phasor at the receiver is determined and shown both for paths reflected in the E- and Fregions, being significantly larger for the latter. The oblique sounding ionogram is constructed and reveals three propagation modes: the E-mode and low and high angle F-mode paths. The time-varying field due to each of these paths is then summed at the receiving location enabling the calculation of the scattering function and also the time realization of the received signal shown as a function of both fast and slow time. This is performed both with and without the presence of the geomagnetic field; in the former case the splitting of the F2-mode into both e- and o-modes is seen. It is also shown how the scattering function can be obtained from the time realization of the channel in a way akin to experimental

  13. Investigation and Development of Data-Driven D-Region Model for HF Systems Impacts

    Science.gov (United States)

    Eccles, J. V.; Rice, D.; Sojka, J. J.; Hunsucker, R. D.

    2002-01-01

    Space Environment Corporation (SEC) and RP Consultants (RPC) are to develop and validate a weather-capable D region model for making High Frequency (HF) absorption predictions in support of the HF communications and radar communities. The weather-capable model will assimilate solar and earth space observations from NASA satellites. The model will account for solar-induced impacts on HF absorption, including X-rays, Solar Proton Events (SPE's), and auroral precipitation. The work plan includes: I . Optimize D-region model to quickly obtain ion and electron densities for proper HF absorption calculations. 2. Develop indices-driven modules for D-region ionization sources for low, mid, & high latitudes including X-rays, cosmic rays, auroral precipitation, & solar protons. (Note: solar spectrum & auroral modules already exist). 3. Setup low-cost monitors of existing HF beacons and add one single-frequency beacon. 4. Use PENEX HF-link database with HF monitor data to validate D-region/HF absorption model using climatological ionization drivers. 5. Develop algorithms to assimilate NASA satellite data of solar, interplanetary, and auroral observations into ionization source modules. 6. Use PENEX HF-link & HF-beacon data for skill score comparison of assimilation versus climatological D-region/HF absorption model. Only some satellites are available for the PENEX time period, thus, HF-beacon data is necessary. 7. Use HF beacon monitors to develop HF-link data assimilation algorithms for regional improvement to the D-region/HF absorption model.

  14. Serpentinization Changes Nd, but not Hf Isotopes of Abyssal Peridotites

    Science.gov (United States)

    Bizimis, M.; Frisby, C. P.; Mallick, S.

    2015-12-01

    Serpentinization of the oceanic lithosphere is a known sink for fluid mobile elements (B, Cl, Li, Sr, etc.), while high field strength elements (HFSE: e.g., Hf, Zr, Ti, Nb) are thought to be unaffected by it. In contrast, the fate of REE during serpentinization is equivocal. Correlations between REE and HFSE concentrations in abyssal peridotites suggest control by magmatic processes (Niu, 2004, J. Pet), while some LREE enrichments in serpentinized peridotites compared to their clinopyroxene (cpx) and Nd, Sr isotope data (Delacour et al., 2008, Chem. Geol.) imply seawater-derived REE addition to the mantle protolith (Paulick et al., 2006, Chem. Geol). To further constrain peridotite-seawater interaction during serpentinization we compare bulk rock and cpx Hf and Nd isotope data in partially (up to ~70%) serpentinized abyssal peridotites (9-16°E South West Indian Ridge). We also present a new method that improves yields in Hf, Nd and Pb separations from depleted (90% of Hf, Zr, Ti are retained in the residue. LA-ICPMS data shows that serpentine after olivine typically has higher LREE/HREE ratios than cpx, pronounced negative Ce anomalies, high U, Sr concentrations and low HFSE, unlike the coexisting cpx. These data are consistent with some seawater-derived LREE addition to peridotite during serpentinization, localized in the serpentine and other secondary phases, while cpx retains the magmatic value. This process will lower the Sm/Nd relative to Lu/Hf ratio in the peridotite and can lead to decoupled radiogenic Hf and unradiogenic Nd isotopes upon recycling and aging. Our data further testifies to the fidelity of Hf isotopes in tracing mantle processes, even in serpentinized rocks.

  15. Joint Efforts Towards European HF Radar Integration

    Science.gov (United States)

    Rubio, A.; Mader, J.; Griffa, A.; Mantovani, C.; Corgnati, L.; Novellino, A.; Schulz-Stellenfleth, J.; Quentin, C.; Wyatt, L.; Ruiz, M. I.; Lorente, P.; Hartnett, M.; Gorringe, P.

    2016-12-01

    During the past two years, significant steps have been made in Europe for achieving the needed accessibility to High Frequency Radar (HFR) data for a pan-European use. Since 2015, EuroGOOS Ocean Observing Task Teams (TT), such as HFR TT, are operational networks of observing platforms. The main goal is on the harmonization of systems requirements, systems design, data quality, improvement and proof of the readiness and standardization of HFR data access and tools. Particular attention is being paid by HFR TT to converge from different projects and programs toward those common objectives. First, JERICO-NEXT (Joint European Research Infrastructure network for Coastal Observatory - Novel European eXpertise for coastal observaTories, H2020 2015 Programme) will contribute on describing the status of the European network, on seeking harmonization through exchange of best practices and standardization, on developing and giving access to quality control procedures and new products, and finally on demonstrating the use of such technology in the general scientific strategy focused by the Coastal Observatory. Then, EMODnet (European Marine Observation and Data Network) Physics started to assemble HF radar metadata and data products within Europe in a uniform way. This long term program is providing a combined array of services and functionalities to users for obtaining free of charge data, meta-data and data products on the physical conditions of European sea basins and oceans. Additionally, the Copernicus Marine Environment Monitoring Service (CMEMS) delivers from 2015 a core information service to any user related to 4 areas of benefits: Maritime Safety, Coastal and Marine Environment, Marine Resources, and Weather, Seasonal Forecasting and Climate activities. INCREASE (Innovation and Networking for the integration of Coastal Radars into EuropeAn marine SErvices - CMEMS Service Evolution 2016) will set the necessary developments towards the integration of existing European

  16. First-principles study of the Hf-based Heusler alloys: Hf2CoGa and Hf2CoIn

    Science.gov (United States)

    Hu, Yan; Zhang, Jian-Min

    2017-01-01

    The electronic structures and magnetic properties of the new Heusler alloys Hf2CoGa and Hf2CoIn have been studied by using the first-principles projector augmented wave (PAW) potential within the generalized gradient approximation (GGA). Both Hf2CoGa and Hf2CoIn Heusler alloys have the half-metallic character and completely (100%) spin polarization at the Fermi level (EF) and the indirect band gaps of 0.733 eV and 0.654 eV, respectively, in the minority spin channel. The total magnetic moments μt are all 2μB per formula unit, linearly scaled with the total number of valence electrons (Zt) by μt=Zt-18 and the atomic magnetic moments have localized character due to less affected by deformations. The origin of the indirect band gaps for these two new Heusler alloys is well understood. These two new Heusler alloys are the ideal candidates for spintronic devices.

  17. Optical remote sensing of the thermosphere with HF pumped artificial airglow

    Science.gov (United States)

    Bernhardt, P. A.; Wong, M.; Huba, J. D.; Fejer, B. G.; Wagner, L. S.; Goldstein, J. A.; Selcher, C. A.; Frolov, V. L.; Sergeev, E. N.

    2000-05-01

    Optical emissions excited by high-power radio waves in the ionosphere can be used to measure a wide variety of parameters in the thermosphere. Powerful high-frequency (HF) radio waves produce energetic electrons in the region where the waves reflect in the F region. These hot or suprathermal electrons collide with atomic oxygen atoms to produce localized regions of metastable O(1D) and O(1S) atoms. These metastables subsequently radiate 630.0 and 557.7 nm, respectively, to produce clouds of HF pumped artificial airglow (HPAA). The shapes of the HPAA clouds are determined by the structure of large-scale (~10 km) plasma irregularities that occur naturally or that develop during ionospheric heating. When the HF wave is operated continuously, the motion of the airglow clouds follows the E×B drift of the plasma. When the HF wave is turned off, the airglow clouds decay by collisional quenching and radiation, expand by neutral diffusion, and drift in response to neutral winds. Images of HPAA clouds, obtained using both continuous and stepped radio wave transmissions, are processed to yield the electric fields, neutral wind vectors, and diffusion coefficients in the upper atmosphere. This technique is illustrated using data that were obtained in March 1993 and 1995 at the ionospheric modification facility near Nizhny Novgorod, Russia. Analysis of HPAA clouds yields zonal plasma drifts of 70 m s-1 eastward at night. On the basis of artificial airglow from energetic electrons generated at 260 km the zonal neutral wind speed was estimated to be 96 m s-1 and the O(1D) diffusion coefficient was determined to be between 0.8 and 1.4×1011cm2s-1. The quenched lifetime of the O(1D) was determined to be 29.4 s. The diffusion and quenching rates are directly related to the atomic and molecular concentrations in the thermosphere. Improvements in the remote-sensing technique may be obtained if the intensity of the artificial airglow emissions is increased. High-power radio

  18. HF omnidirectional spectral CW auroral radar (HF-OSCAR) at very high latitude. Part 1: Technique

    Science.gov (United States)

    Olesen, J. K.; Jacobsen, K. E.; Stauning, P.; Henriksen, S.

    1983-12-01

    An HF system for studies of very high latitude ionospheric irregularities was described. Radio aurora from field-aligned E-region irregularities of the Slant E Condition type were discussed. The complete system combines an ionosonde, a 12 MHz pulse radar and a 12 MHz bistatic CW Doppler-range set-up. The two latter units use alternately a 360 deg rotating Yagi antenna. High precision oscillators secure the frequency stability of the Doppler system in which the received signal is mixed down to a center frequency of 500 Hz. The Doppler shift range is max + or - 500 Hz. The received signal is recorded in analog form on magnetic tape and may be monitored visually and audibly. Echo range of the CW Doppler signal is obtained by a 150 Hz amplitude modulation of the transmitted signal and phase comparison with the backscattered signal.

  19. Comparison of HfAlO, HfO2/Al2O3, and HfO2 on n-type GaAs using atomic layer deposition

    Science.gov (United States)

    Lu, Bin; Lv, Hongliang; Zhang, Yuming; Zhang, Yimen; Liu, Chen

    2016-11-01

    Different high-permittivity (high-k) gate dielectric structures of HfO2, HfAlO, and HfO2/Al2O3 deposited on HF-etched n-GaAs using ALD have been investigated. It has been demonstrated that the stacked structure of HfO2/Al2O3 has the lowest interface state density of 8.12 × 1012eV-1 cm-2 due to the "self-cleaning" reaction process, but the sample of HfAlO shows much better frequency dispersion and much higher dielectric permittivity extracted from the C-V curves. The investigation reveals that the electrical properties of gate dielectrics are improved by introducing alumina into HfO2.

  20. Nonlinear Conte-Zbilut-Federici (CZF Method of Computing LF/HF Ratio: A More Reliable Index of Changes in Heart Rate Variability

    Directory of Open Access Journals (Sweden)

    Vernon Bond Jr

    2016-09-01

    Full Text Available Objectives: Acupuncture treatments are safe and effective for a wide variety of diseases involving autonomic dysregulation. Heart rate variability (HRV is a noninvasive method for assessing sympathovagal balance. The low frequency/high frequency (LF/HF spectral power ratio is an index of sympathovagal influence on heart rate and of cardi

  1. Twin peak HF QPOs as a spectral imprint of dual oscillation modes of accretion tori

    CERN Document Server

    Bakala, Pavel; Török, Gabriel; Šrámková, Eva; Abramowicz, Marek A; Vincent, Frederic H; Mazur, Grzegorz P

    2015-01-01

    High frequency (millisecond) quasi-periodic oscillations (HF QPOs) are observed in the X-ray power-density spectra of several microquasars and low mass X-ray binaries. Two distinct QPO peaks, so-called twin peak QPOs, are often detected simultaneously exhibiting their frequency ratio close or equal to 3/2. Following the analytic theory and previous studies of observable spectral signatures, we aim to model the twin peak QPOs as a spectral imprint of specific dual oscillation regime defined by a combination of the lowest radial and vertical oscillation mode of optically thick slender tori with constant specific angular momentum. We examined power spectra and fluorescent K$\\alpha$ iron line profiles for two different simulation setups with the mode frequency relations corresponding to the epicyclic resonance HF QPOs model and modified relativistic precession QPOs model. We use relativistic ray-tracing implemented in parallel simulation code LSDplus. In the background of the Kerr spacetime geometry, we analyze t...

  2. Remote Geophysical Observatory in Antarctica with HF Data Transmission: A Review

    Directory of Open Access Journals (Sweden)

    Joan Lluis Pijoan

    2014-08-01

    Full Text Available The geophysical observatory in the Antarctic Spanish Station, Juan Carlos I (ASJI, on Livingston Island, has been monitoring the magnetic field in the Antarctic region for more than fifteen years. In 2004, a vertical incidence ionospheric sounder completed the observatory, which brings a significant added value in a region with low density of geophysical data. Although the ASJI is only operative during the austral summer, the geomagnetic station records the data throughout the year. A High Frequency (HF transmission system was installed in 2004 in order to have the geomagnetic data available during the whole year. As the power supply is very limited when the station is not operative, we had to design a low-power HF transceiver with a very simple antenna, due to environmental aspects. Moreover, the flow of information was unidirectional, so the modulation had to be extremely robust since there is no retransmission in case of error. This led us to study the main parameters of the ionospheric channel and to design new modulations specially adapted to very low signal to noise scenarios with high levels of interference. In this paper, a review of the results of our remote geophysical observatory and associated transmission system in Antarctica during the last decade is presented.

  3. HfO2 Gate Dielectrics for Future Generation of CMOS Device Application

    Institute of Scientific and Technical Information of China (English)

    H.Y.Yu; J.F.Kang; Ren Chi; M.F.Li; D.L.Kwong

    2004-01-01

    The material and electrical properties of HfO2 high-k gate dielectric are reported.In the first part,the band alignment of HfO2 and (HfO2)x(Al2O3)1-x to (100)Si substrate and their thermal stability are studied by X-ray photoelectron spectroscopy and TEM.The energy gap of (HfO2)x(Al2O3)1-x,the valence band offset,and the conduction band offset between (HfO2)x(Al2O3)1-x and the Si substrate as functions of x are obtained based on the XPS results.Our XPS results also demonstrate that both the thermal stability and the resistance to oxygen diffusion of HfO2 are improved by adding Al to form Hf aluminates.In the second part,a thermally stable and high quality HfN/HfO2 gate stack is reported.Negligible changes in equivalent oxide thickness (EOT),gate leakage,and work function (close to Si mid-gap) of HfN/HfO2 gate stack are demonstrated even after 1000℃ post-metal annealing(PMA),which is attributed to the superior oxygen diffusion barrier of HfN as well as the thermal stability of the HfN/HfO2 interface.Therefore,even without surface nitridation prior to HfO2 deposition,the EOT of HfN/HfO2 gate stack has been successfully scaled down to less than 1nm after 1000℃ PMA with excellent leakage and long-term reliability.The last part demonstrates a novel replacement gate process employing a HfN dummy gate and sub-1nm EOT HfO2 gate dielectric.The excellent thermal stability of the HfN/HfO2 gate stack enables its use in high temperature CMOS processes.The replacement of HfN with other metal gate materials with work functions adequate for n- and p-MOS is facilitated by a high etch selectivity of HfN with respect to HfO2,without any degradation to the EOT,gate leakage,or TDDB characteristics of HfO2.

  4. Pressure-induced novel compounds in the Hf-O system from first-principles calculations

    Science.gov (United States)

    Zhang, Jin; Oganov, Artem R.; Li, Xinfeng; Xue, Kan-Hao; Wang, Zhenhai; Dong, Huafeng

    2015-11-01

    Using first-principles evolutionary simulations, we have systematically investigated phase stability in the Hf-O system at pressure up to 120 GPa. New compounds Hf5O2,Hf3O2 , HfO, and HfO3 are discovered to be thermodynamically stable at certain pressure ranges. Two new high-pressure phases are found for Hf2O : one with space group Pnnm and anti-CaCl2-type structure, another with space group I 41/amd. Pnnm-HfO3 shows interesting structure, simultaneously containing oxide O2 - and peroxide [O-O]2 - anions. Remarkably, it is P 6 ¯2 m -HfO rather than OII-HfO2 that exhibits the highest mechanical characteristics among Hf-O compounds. Pnnm-Hf2O , Imm2-Hf5O2 ,P 3 ¯1 m -Hf2O , and P 4 ¯m 2 -Hf2O3 phases also show superior mechanical properties; theoretically these phases become metastable phases to ambient pressure and their properties can be exploited.

  5. Effect of HF leaching on 14C dates of pottery

    Science.gov (United States)

    Goslar, Tomasz; Kozłowski, Janusz; Szmyt, Marzena; Czernik, Justyna

    2013-01-01

    This paper presents the experiments with 14C dating of two potsherds, which contained carbon dispersed rather homogeneously in their clay fabric. After AAA treatment, the potsherds still appeared to be contaminated with young carbon, presumably connected with humic acids. To make removal of humic acids more effective, we treated the sherds with HF acid of different concentration. The 14C results obtained demonstrate that HF treatment indeed helps to remove humic contaminants, but it also mobilizes carbon bound to raw clay, which may make 14C dates too old. We conclude therefore, that using a simple combination of HF and AAA treatment seems insufficient in reliable 14C dating of carbon homogeneously dispersed in the volume of potsherds.

  6. 100 days of ELF/VLF generation via HF heating with HAARP

    Science.gov (United States)

    Cohen, M. B.; Gołkowski, M.

    2013-10-01

    Extremely low frequency/very low frequency (ELF/VLF) radio waves are difficult to generate with conventional antennas. Ionospheric high frequency (HF) heating facilities generate ELF/VLF waves via modulated heating of the lower ionosphere. HF heating of the ionosphere changes the lower ionospheric conductivity, which in the presence of natural currents such as the auroral electrojet creates an antenna in the sky when heating is modulated at ELF/VLF frequencies. We present a summary of nearly 100 days of ELF/VLF wave generation experiments at the 3.6 MW High Frequency Active Auroral Research Program (HAARP) facility near Gakona, Alaska, at a variety of ELF/VLF frequencies, seasons, and times of day. We present comprehensive statistics of generated ELF/VLF magnetic fields observed at a nearby site, in the 500-3500 Hz band. Transmissions with a specific HF beam configuration (3.25 MHz, vertical beam, amplitude modulation) are isolated so the data comparison is self-consistent, across nearly 5 million individual measurements of either a tone or a piece of a frequency-time ramp. There is a minimum in the average generation close to local midnight. It is found that generation during local nighttime is on average weaker but more highly variable, with a small number of very strong generation periods. Signal amplitudes from day to day may vary by as much as 20-30 dB. Generation strengthens by ˜5 dB during the first ˜30 min of transmission, which may be a signature of slow electron density changes from sustained HF heating. Theoretical calculations are made to relate the amplitude observed to the power injected into the waveguide and reaching 250 km. The median power generated by HAARP and injected into the waveguide is ˜0.05-0.1 W in this baseline configuration (vertical beam, 3.25 MHz, amplitude modulation) but may have generated hundreds of watts for brief durations. Several efficiency improvements have improved the ELF/VLF wave generation efficiency further.

  7. The Status of Rotational Nonequilibrium in HF Chemical Lasers

    Science.gov (United States)

    1986-05-01

    later study from the same laboratory, Copeland et al. 5 3 used a NdYAG dye laser to pump HF into v = 2, j, and an HF pulsed laser to probe various P 2(J... Weston , Jr., J. Chem. Phys. 77, 4776 (1982). 51. J. J. Hinchen and R. H. Hobbs, Appl. Phys. 50, 628 (1979). 52. j. K. Lambert, G. M. Jursich, and F. F...Crim, Chem. Phys. Lett. 71, 258 (1980). 53. R. A. Copeland , D. J. Pearson, and F. F. Crim, Chem. Phys. Lett. 81, 541 (1981). 54. T. J. Foster and F. F

  8. HF-induced airglow at magnetic zenith: theoretical considerations

    Directory of Open Access Journals (Sweden)

    E. V. Mishin

    2005-01-01

    Full Text Available Observations of airglow at 630nm (red line and 557.7nm (green line during HF modification experiments at the High Frequency Active Auroral Research Program (HAARP heating facility are analyzed. We propose a theoretical framework for understanding the generation of Langmuir and ion acoustic waves during magnetic zenith injections. We show that observations of HF-induced airglow in an underdense ionosphere as well as a decrease in the height of the emitting volume are consistent with this scenario.

  9. HF-hash : Hash Functions Using Restricted HFE Challenge-1

    CERN Document Server

    Dey, Dhananjoy; Gupta, Indranath Sen

    2009-01-01

    Vulnerability of dedicated hash functions to various attacks has made the task of designing hash function much more challenging. This provides us a strong motivation to design a new cryptographic hash function viz. HF-hash. This is a hash function, whose compression function is designed by using first 32 polynomials of HFE Challenge-1 with 64 variables by forcing remaining 16 variables as zero. HF-hash gives 256 bits message digest and is as efficient as SHA-256. It is secure against the differential attack proposed by Chabaud and Joux as well as by Wang et. al. applied to SHA-0 and SHA-1.

  10. Hf--Co--B alloys as permanent magnet materials

    Energy Technology Data Exchange (ETDEWEB)

    McGuire, Michael Alan; Rios, Orlando; Ghimire, Nirmal Jeevi

    2017-01-24

    An alloy composition is composed essentially of Hf.sub.2-XZr.sub.XCo.sub.11B.sub.Y, wherein 0Hf.sub.2-XZr.sub.XCo.sub.11B.sub.Y, wherein 0.ltoreq.X<2 and 0

  11. First HF radar measurements of summer mesopause echoes at SURA

    Directory of Open Access Journals (Sweden)

    A. N. Karashtin

    Full Text Available HF sounding of the mesosphere was first carried out at SURA in summer 1994 at frequencies in the range 8–9 MHz using one of the sub-arrays of the SURA heating facility. The observations had a range resolution of 3 km. Almost all measurements indicated the presence of strong radar returns from altitudes between 83 and 90 km with features very similar to VHF measurements of mesopause summer echoes at mid-latitudes and polar mesopause summer echoes. In contrast to VHF observations, HF mesopause echoes are almost always present.

  12. First HF radar measurements of summer mesopause echoes at SURA

    Science.gov (United States)

    Karashtin, A. N.; Shlyugaev, Y. V.; Abramov, V. I.; Belov, I. F.; Berezin, I. V.; Bychkov, V. V.; Eryshev, E. B.; Komrakov, G. P.

    1997-07-01

    HF sounding of the mesosphere was first carried out at SURA in summer 1994 at frequencies in the range 8-9 MHz using one of the sub-arrays of the SURA heating facility. The observations had a range resolution of 3 km. Almost all measurements indicated the presence of strong radar returns from altitudes between 83 and 90 km with features very similar to VHF measurements of mesopause summer echoes at mid-latitudes and polar mesopause summer echoes. In contrast to VHF observations, HF mesopause echoes are almost always present.

  13. European coordination for coastal HF radar data in EMODnet Physics

    Science.gov (United States)

    Mader, Julien; Novellino, Antonio; Gorringe, Patrick; Griffa, Annalisa; Schulz-Stellenfleth, Johannes; Montero, Pedro; Montovani, Carlo; Ayensa, Garbi; Vila, Begoña; Rubio, Anna; Sagarminaga, Yolanda

    2015-04-01

    Historically, joint effort has been put on observing open ocean, organizing, homogenizing, sharing and reinforcing the impact of the acquired information based on one technology: ARGO with profilers Argo floats, EuroSites, ESONET-NoE, FixO3 for deep water platforms, Ferrybox for stations in ships of opportunities, and GROOM for the more recent gliders. This kind of networking creates synergies and makes easier the implementation of this source of data in the European Data exchange services like EMODnet, ROOSs portals, or any applied services in the Blue economy. One main targeted improvement in the second phase of EMODnet projects is the assembling of data along coastline. In that sense, further coordination is recommended between platform operators around a specific technology in order to make easier the implementation of the data in the platforms (4th EuroGOOS DATAMEQ WG). HF radar is today recognized internationally as a cost-effective solution to provide high spatial and temporal resolution current maps (depending on the instrument operation frequency, covering from a few kilometres offshore up to 200 km) that are needed for many applications for issues related to ocean surface drift or sea state characterization. Significant heterogeneity still exists in Europe concerning technological configurations, data processing, quality standards and data availability. This makes more difficult the development of a significant network for achieving the needed accessibility to HF Radar data for a pan European use. EuroGOOS took the initiative to lead and coordinate activities within the various observation platforms by establishing a number of Ocean Observing Task Teams such as HF-Radars. The purpose is to coordinate and join the technological, scientific and operational HF radar communities at European level. The goal of the group is on the harmonization of systems requirements, systems design, data quality, improvement and proof of the readiness and standardization of

  14. Predicting percentage of individuals consuming foods from percentage of households purchasing foods to improve the use of household budget surveys in estimating food chemical intakes

    NARCIS (Netherlands)

    Lambe, J.; Kearney, J.; Becker, W.; Hulshof, K.; Dunne, A.; Gibney, M.J.

    1998-01-01

    Objective: To examine the hypothesis that there is sufficient agreement between percentage of households purchasing selected foods using household budget surveys and percentage of individuals consuming these foods as determined in individual-based surveys to allow the former to act as a surrogate fo

  15. Effect of Al addition on mechanical properties and microstructure of refractory Al{sub x}HfNbTaTiZr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Chun-Ming, E-mail: clin112@asu.edu; Juan, Chien-Chang; Chang, Chia-Hsiu; Tsai, Che-Wei; Yeh, Jien-Wei, E-mail: jwyeh@mx.nthu.edu.tw

    2015-03-05

    Highlights: • The study developed a series of refractory Al{sub x}HfNbTaTiZr HEAs. • The aim to improve strength, and reduce density of the very ductile base alloy. • These HEAs mainly consist of a simple BCC solid solution. • The addition of Al significantly improved the strength characteristics. • Solution hardening led to a decrease in ductility. - Abstract: This study developed a series of refractory Al{sub x}HfNbTaTiZr high-entropy alloys (HEAs) with an aim to improve strength, and reduce density of the very ductile base alloy HfNbTaTiZr. Despite the diversity of crystal structures among the constituent elements, all the HEAs are single solid solution phase with body-centered cubic (BCC) structure. The addition of Al significantly improves the strength but reduces the ductility due to large solution hardening. The linear relation between yield strength and atomic percentage of Al suggests that the strengthening effect of a certain element in a single-phase HEA alloy can be explained based on quasi-binary alloy concept. Crack formations in deformed AlHfNbTaTiZr alloy with the lowest fracture strain are mainly along the boundaries between dendrite and interdendrite. This agrees with its large deviation of Al content and thus strength between dendrite and interdendrite.

  16. Evolution of E2 transition strength in deformed hafnium isotopes from new measurements on $^{172}$Hf, $^{174}$Hf, and $^{176}$Hf

    CERN Document Server

    Rudigier, M; Dannhoff, M; Gerst, R-B; Jolie, J; Saed-Samii, N; Stegemann, S; Régis, J-M; Robledo, L M; Rodríguez-Guzmán, R; Blazhev, A; Fransen, Ch; Warr, N; Zell, K O

    2015-01-01

    The available data for E2 transition strengths in the region between neutron-deficient Hf and Pt isotopes are far from complete. More and precise data are needed to enhance the picture of structure evolution in this region and to test state-of-the-art nuclear models. In a simple model, the maximum collectivity is expected at the middle of the major shell. However, for actual nuclei, this picture may no longer be the case, and one should use a more realistic nuclear-structure model. We address this point by studying the spectroscopy of Hf. We remeasure the 2^+_1 half-lives of 172,174,176Hf, for which there is some disagreement in the literature. The main goal is to measure, for the first time, the half-lives of higher-lying states of the rotational band. The new results are compared to a theoretical calculation for absolute transition strengths. The half-lives were measured using \\gamma-\\gamma and conversion-electron-\\gamma delayed coincidences with the fast timing method. For the determination of half-lives i...

  17. 42 CFR 455.102 - Determination of ownership or control percentages.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 4 2010-10-01 2010-10-01 false Determination of ownership or control percentages... Information by Providers and Fiscal Agents § 455.102 Determination of ownership or control percentages. (a... percentages of ownership in each entity. For example, if A owns 10 percent of the stock in a corporation which...

  18. 7 CFR 51.308 - Methods of sampling and calculation of percentages.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Methods of sampling and calculation of percentages. 51..., CERTIFICATION, AND STANDARDS) United States Standards for Grades of Apples Methods of Sampling and Calculation of Percentages § 51.308 Methods of sampling and calculation of percentages. (a) When the...

  19. 26 CFR 1.410(b)-5 - Average benefit percentage test.

    Science.gov (United States)

    2010-04-01

    ... 26 Internal Revenue 5 2010-04-01 2010-04-01 false Average benefit percentage test. 1.410(b)-5...) INCOME TAX (CONTINUED) INCOME TAXES Pension, Profit-Sharing, Stock Bonus Plans, Etc. § 1.410(b)-5 Average benefit percentage test. (a) General rule. A plan satisfies the average benefit percentage test of...

  20. Identification of Hierarchies of Student Learning about Percentages Using Rasch Analysis

    Science.gov (United States)

    Burfitt, Joan

    2013-01-01

    A review of the research literature indicated that there were probable orders in which students develop understandings and skills for calculating with percentages. Such calculations might include using models to represent percentages, knowing fraction equivalents, selection of strategies to solve problems and determination of percentage change. To…

  1. Structural determination of a highly stable metal-organic framework with possible application to interim radioactive waste scavenging: Hf-UiO-66

    Science.gov (United States)

    Jakobsen, Søren; Gianolio, Diego; Wragg, David S.; Nilsen, Merete Hellner; Emerich, Hermann; Bordiga, Silvia; Lamberti, Carlo; Olsbye, Unni; Tilset, Mats; Lillerud, Karl Petter

    2012-09-01

    High-resolution synchrotron radiation x-ray powder diffraction (HR-XRPD) combined with Hf L3-edge extended x-ray absorption fine structure allowed us to determine the structure of a Hf-UiO-66 metal-organic framework (MOF) showing that it is isoreticular to Zr-UiO-66 MOF [Cavka , J. Am. Chem. Soc.JACSAT0002-786310.1021/ja8057953 130, 13850 (2008).]. Thermal gravimetric measurements (coupled with mass spectroscopy) and temperature-dependent synchrotron radiation XRPD proved the high thermal stability of the Hf-UiO-66 MOF. The Langmuir surface area (849 m2/g) combined with the high stability of the UiO-66 framework and with the high neutron absorption cross section of Hf suggest that among all microporous crystalline materials the Hf-UiO-66 MOF possesses the physical and chemical requirements for the interim storage of radioactive waste in a much safer way than is currently available. The first results proving the synthesis of a MOF material with UiO-66 topology realized by a B-containing linker are also reported, allowing a further improvement of the neutron shielding power of this class of materials.

  2. Modulation of auroral electrojet currents using dual modulated HF beams with ELF phase offset, a potential D-region ionospheric diagnostic

    Science.gov (United States)

    GołKowski, M.; Cohen, M. B.; Moore, R. C.

    2013-05-01

    Experiments at the ionospheric heating facility of the High Frequency Active Auroral Research Program (HAARP) are performed employing dual HF beams amplitude modulated at ELF/VLF with a phase offset between the two modulation waveforms. The amplitude of the observed ELF/VLF waves is strongly dependent on the imposed ELF/VLF phase offset, the modulation waveform, and the orientation of the HF beams. Data from two ground stations are interpreted using simulations of modulated heating power envelopes as well as a comprehensive model of ionospheric ELF/VLF generation. It is found that two colocated vertical beams HF beams excite a single ionospheric ELF/VLF source, but independent ELF/VLF sources can be induced in the ionospheric region above the heater if the HF beams are offset from zenith to intersect at their 3 dB points. Furthermore, the use of two vertical HF beams with ELF phase offset is found to be a potential diagnostic method for the ionospheric D region.

  3. Comparative study of atomic-layer-deposited HfO2/Al2O3, Hf0.8Al0.2Ox and Hf0.5Al0.5Ox on N-GaAs

    Science.gov (United States)

    Yu, Xinjiang; Lv, Hongliang; Zhang, Yuming; Zhang, Yimen; Qin, Zaiyang

    2016-11-01

    Interfacial properties of n-GaAs metal-oxide-semiconductor (MOSCAPs) with the gate dielectrics of HfO2/Al2O3, Hf0.8Al0.2Ox and Hf0.5Al0.5Ox are investigated. The results reveal that Hf0.5Al0.5Ox has larger permittivity and lower interface trap density than that of HfO2/Al2O3. In order to explain the result from the physical perspective, the XPS tests of all three samples are performed. It is found that the main reason to form interface trap of three samples treated with 500 °C post-deposition annealing, is attributed to the interfacial component of Ga2O3 and The Hf0.5Al0.5Ox dielectric is beneficial to reducing the formation of Ga2O3.

  4. Plasma modifications induced by an X-mode HF heater wave in the high latitude F region of the ionosphere

    Science.gov (United States)

    Blagoveshchenskaya, N. F.; Borisova, T. D.; Yeoman, T. K.; Rietveld, M. T.; Häggström, I.; Ivanova, I. M.

    2013-12-01

    We presented experimental results of strong plasma modifications induced by X-mode powerful HF radio waves injected towards the magnetic zenith into the high latitude F region of the ionosphere. The experiments were conducted in 2009-2011 using the EISCAT Heating facility, UHF incoherent scatter radar and the EISCAT ionosonde at Tromsø, Norway; and the CUTLASS SuperDARN HF coherent radar at Hankasalmi, Finland. The results showed that the X-mode HF pump wave can generate strong small-scale artificial field aligned irregularities (AFAIs) in the F region of the high-latitude ionosphere. These irregularities, with spatial scales across the geomagnetic field of the order of 9-15 m, were excited when the heater frequency (fH) was above the ordinary-mode critical frequency (foF2) by 0.1-1.2 MHz. It was found that the X-mode AFAIs appeared between 10 s and 4 min after the heater is turned on. Their decay time varied over a wide range between 3 min and 30 min. The excitation of X-mode AFAIs was accompanied by electron temperature (Te) enhancements and an increase in the electron density (Ne) depending on the effective radiated power (ERP). Under ERPs of about 75-180 MW the Te enhances up to 50% above the background level and an increase in Ne of up to 30% were observed. Dramatic changes in the Te and Ne behavior occurred at effective radiated powers of about 370-840 MW, when the Ne and Te values increased up to 100% above the background ones. It was found that AFAIs, Ne and Te enhancements occurred, when the extraordinary-mode critical frequency (fxF2) lied in the frequency range fH-fce/2≤fxF2≤fH+fce/2, where fce is the electron gyrofrequency. The strong Ne enhancements were observed only in the magnetic field-aligned direction in a wide altitude range up to the upper limit of the UHF radar measurements. In addition, the maximum value of Ne is about 50 km higher than the Te enhancement peak. Such electron density enhancements (artificial ducts) cannot be explained by

  5. The multilayer Fe/Hf studied with slow positron beam

    Science.gov (United States)

    Murashige, Y.; Tashiro, M.; Nakajyo, T.; Koizumi, T.; Kanazawa, I.; Komori, F.; Ito, Y.

    1997-04-01

    The positron annihilation parameter versus the incident positron energy is measured in the thin Fe films and the Fe/Hf bilayer on silica substrate, by means of the variable energetic slow-positron beam technique. We have analyzed the change in open-volume spaces and vacancy-type defects among the Fe microcrystals in these thin films with the deposition temperature.

  6. A CMOS OTA for HF filters with programmable transfer function

    NARCIS (Netherlands)

    van de Zwan, Eric J.; Klumperink, Eric A.M.; Seevinck, E.; Seevinck, Evert

    1991-01-01

    A CMOS operational transconductance amplifier (OTA) for programmable HF filters is presented. When used in an OTA-C integrator, the unity-gain frequency phase error remains less than 0.3° for frequencies up to more than one tenth of the OTA bandwidth. The OTA has built-in phase compensation, which

  7. Hf isotope evidence for a hidden mantle reservoir

    DEFF Research Database (Denmark)

    Bizzarro, Martin; Simonetti, A.; Stevenson, R.K.

    2002-01-01

    High-precision Hf isotopic analyses and U-Pb ages of carbonatites and kimberlites from Greenland and eastern North America, including Earth's oldest known carbonatite (3 Ga), indicate derivation from an enriched mantle source. This previously unidentified mantle reservoir-marked by an unradiogeni...

  8. Origin of excess 176Hf in meteorites

    DEFF Research Database (Denmark)

    Thrane, Kristine; Connelly, James; Bizzarro, Martin

    2010-01-01

    After considerable controversy regarding the (176)Lu decay constant (lambda(176)Lu), there is now widespread agreement that (1.867 +/- 0.008) x 10(-11) yr(-1) as confirmed by various terrestrial objects and a 4557 Myr meteorite is correct. This leaves the (176)Hf excesses that are correlated with...

  9. Self-diffusion of Er and Hf inpure and HfO/sub 2/-doped polycrystalline Er/sub 2/O/sub 3/. [Hf-175 and Er-169

    Energy Technology Data Exchange (ETDEWEB)

    Scheidecker, R.W.

    1979-01-01

    Using a tracer technique, self-diffusion of Er and Hf was measured over the approximate temperature interval of 1600 to 1970/sup 0/C in pure and HfO/sub 2/-doped polycryatalline Er/sub 2/O/sub 3/. Up to about 10 m/o HfO/sub 2/ dopant level, the Er self-diffusion coefficients followed a relationship based on cation vacancies. Above 10 m/o HfO/sub 2/, deviation from this relationship occurred, apparently due to clustering of cation vacancies and oxygen interstitials around the dopant hafnia ion. The activation energy for the self-diffusion of Er in pure Er/sub 2/O/sub 3/ was 82.2 Kcal/mole and increased with the HfO/sub 2/ dopant level present. Self-diffusion of Hf was measured in pure Er/sub 2/O/sub 3/ having two impurity levels, and a separation of the grain boundary. The volume diffusion of Hf showed both extrinsic and intrinsic behavior with the transition temperature increasing with the impurity level present in Er/sub 2/O/sub 3/. The activation energy for Hf volume diffusion in the intrinsic region was high, i.e. 235 -+ 9.5 Kcal/mole. The grain boundary diffusion was apparently extrinsic over the entire temperature interval Very low Hf self diffusion rates were found in both pure and HfO/sub 2/ doped Er/sub 2/O/sub 3/ compositions. Despite a clustering effect, the HfO/sub 2/ dopant increased the Hf volume diffusion coefficients.

  10. Helium implanted $\\rm\\underline{Al}$Hf as studied by 181Ta TDPAC

    Indian Academy of Sciences (India)

    R Govindaraj; K P Gopinathan; B Viswanathan

    2000-06-01

    Time differential perturbed angular correlation (TDPAC) measurement on $\\rm\\underline{Al}$Hf reference sample has shown that a fraction 0.88 of probe nuclei are defect free and are occupying the substitutional sites in fcc Al matrix, and the remaining are associated with Hf solute clusters. Measurements on helium implanted sample indicate the binding of helium associated defects by Hf solute clusters. Isochronal annealing measurements indicate the dissociation of the helium implantation induced defects from Hf solute clusters for annealing treatments beyond 650 K. On comparison of the present results with that reported in $\\rm\\underline{Cu}$Hf subjected to identical helium implantation, it is inferred that the Hf solute clusters in $\\rm\\underline{Al}$Hf bind less strongly the helium associated defects than in $\\rm\\underline{Cu}$Hf.

  11. Processing and crystallographic structure of non-equilibrium Si-doped HfO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Dong; Fancher, Chris M.; Esteves, Giovanni; Jones, Jacob L., E-mail: jacobjones@ncsu.edu [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Zhao, Lili [School of Information Science and Technology, Northwest University, Xi' an 710127 (China)

    2015-06-28

    Si-doped HfO{sub 2} was confirmed to exist as a non-equilibrium state. The crystallographic structures of Si-doped HfO{sub 2} were studied using high-resolution synchrotron X-ray diffraction and the Rietveld refinement method. Incorporation of Si into HfO{sub 2} and diffusion of Si out of (Hf,Si)O{sub 2} were determined as a function of calcination temperature. Higher thermal energy input at elevated calcination temperatures resulted in the formation of HfSiO{sub 4}, which is the expected major secondary phase in Si-doped HfO{sub 2}. The effect of SiO{sub 2} particle size (nano- and micron-sized) on the formation of Si-doped HfO{sub 2} was also determined. Nano-crystalline SiO{sub 2} was found to incorporate into HfO{sub 2} more readily.

  12. Data of evolutionary structure change: 1CLMA-2HF5A [Confc[Archive

    Lifescience Database Archive (English)

    Full Text Available 1CLMA-2HF5A 1CLM 2HF5 A A LTEEQIAEFKEAFALFDKDGDGTITTKELGTVMRSLGQN...PTEAELQDMINEVDADGNGTIDFPEFLSLMARKMKEQDSEEELIEAFKVFDRDGNGLISAAELRHVMTNLGEKL--TDDEVDEMIREADIDGDGHINYEEFVRMMVS-...ntryChain> 1CLM A 1CLMA LGEKL--TD...ne> 1CLM A 1CLMA

  13. Geographic variations in the PARADIGM-HF heart failure trial.

    Science.gov (United States)

    Kristensen, Søren Lund; Martinez, Felipe; Jhund, Pardeep S; Arango, Juan Luis; Bĕlohlávek, Jan; Boytsov, Sergey; Cabrera, Walter; Gomez, Efrain; Hagège, Albert A; Huang, Jun; Kiatchoosakun, Songsak; Kim, Kee-Sik; Mendoza, Iván; Senni, Michele; Squire, Iain B; Vinereanu, Dragos; Wong, Raymond Ching-Chiew; Gong, Jianjian; Lefkowitz, Martin P; Rizkala, Adel R; Rouleau, Jean L; Shi, Victor C; Solomon, Scott D; Swedberg, Karl; Zile, Michael R; Packer, Milton; McMurray, John J V

    2016-11-01

    The globalization of clinical trials has highlighted geographic variations in patient characteristics, event rates, and treatment effects. We investigated these further in PARADIGM-HF, the largest and most globally representative trial in heart failure (HF) to date. We looked at five regions: North America (NA) 602 (8%), Western Europe (WE) 1680 (20%), Central/Eastern Europe/Russia (CEER) 2762 (33%), Latin America (LA) 1433 (17%), and Asia-Pacific (AP) 1487 (18%). Notable differences included: WE patients (mean age 68 years) and NA (65 years) were older than AP (58 years) and LA (63 years) and had more coronary disease; NA and CEER patients had the worst signs, symptoms, and functional status. North American patients were the most likely to have a defibrillating-device (54 vs. 2% AP) and least likely prescribed a mineralocorticoid receptor antagonist (36 vs. 65% LA). Other evidence-based therapies were used most frequently in NA and WE. Rates of the primary composite outcome of cardiovascular (CV) death or HF hospitalization (per 100 patient-years) varied among regions: NA 13.6 (95% CI 11.7-15.7) WE 9.6 (8.6-10.6), CEER 12.3 (11.4-13.2), LA 11.2 (10.0-12.5), and AP 12.5 (11.3-13.8). After adjustment for prognostic variables, relative to NA, the risk of CV death was higher in LA and AP and the risk of HF hospitalization lower in WE. The benefit of sacubitril/valsartan was consistent across regions. There were many regional differences in PARADIGM-HF, including in age, symptoms, comorbidity, background therapy, and event-rates, although these did not modify the benefit of sacubitril/valsartan. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifier: NCT01035255. © The Author 2016. Published by Oxford University Press on behalf of the European Society of Cardiology.

  14. Mid-Latitude Mobile Wideband HF- NVIS Channel Analysis: Part 1

    Science.gov (United States)

    2017-09-14

    communications (SATCOM) for beyond line-of- sight (LOS) links. However, standard HF systems operating over a 3-kHz bandwidth do not provide sufficient...wideband mid-latitude HF channel soundings and three-dimensional (3-D) ray-tracing simulations to develop a statistical model of a particular nearly...46 5 THE HF-NVIS CHANNEL SOUNDING SYSTEM ...................................................................... 47 5.1 TRANSMIT AND RECEIVE HF

  15. Impact of famous CEDAR, GEM and ISTP geomagnetic Storms on HF Radio Propagation

    Science.gov (United States)

    Blagoveshchensky, D.; Sergeeva, M.

    The mighty geomagnetic storms due to the extraordinary Sun s activity cause as a rule some impacts in these areas radiation effects on human and satellites commercial airlines outages electric power and other geomagnetic effects navigation and communication GPS effects ionospheric disturbances HF communication effects Therefore our scientific understanding of this activity is very important Joint efforts for example within the framework of the CAWSES enable progress in our ability to i identify critical inputs to specify the geospace environment at a level needed to minimize impacts on technology human society and life and ii support the development of robust models that predict conditions in geospace based on understanding of the Sun-Earth system and all of its interacting components In this study influence of 14 geomagnetic storms from a list of CEDAR GEM and ISTP storms within 1997-99 on radio propagation conditions have been investigated These conditions were estimated through variations of the MOF and LOF the maximum and lowest operation frequencies on each path from three high-latitude HF radio paths of North-west Russia before during and after a storm It was shown that the storm impact on the ionosphere and radio propagation for each storm has an individual character Nevertheless the common character of the certain manifestations during storm-time was revealed For example the frequency range MOF - LOF is getting wider several hours before a storm then it is sharply narrow during a storm-time and further it is expanded again several

  16. Validation of the CUTLASS HF radar gravity wave observing capability using EISCAT CP-1 data

    Directory of Open Access Journals (Sweden)

    N. F. Arnold

    Full Text Available Quasi-periodic fluctuations in the returned ground-scatter power from the SuperDARN HF radars have been linked to the passage of medium-scale gravity waves. We have applied a technique that extracts the first radar range returns from the F-region to study the spatial extent and characteristics of these waves in the CUTLASS field-of-view. Some ray tracing was carried out to test the applicability of this method. The EISCAT radar facility at Tromsø is well within the CUTLASS field-of-view for these waves and provides a unique opportunity to assess independently the ability of the HF radars to derive gravity wave information. Results from 1st March, 1995, where the EISCAT UHF radar was operating in its CP-1 mode, demonstrate that the radars were in good agreement, especially if one selects the electron density variations measured by EISCAT at around 235 km. CUTLASS and EISCAT gravity wave observations complement each other; the former extends the spatial field of view considerably, whilst the latter provides detailed vertical information about a range of ionospheric parameters.

    Key words. Ionosphere (ionosphere – atmosphere interactions · Meteorology and atmospheric dynamics (thermospheric dynamics · Radio science (ionospheric propagations

  17. Pulse-shape discrimination with Cs2HfCl6 crystal scintillator

    Science.gov (United States)

    Cardenas, C.; Burger, A.; Goodwin, B.; Groza, M.; Laubenstein, M.; Nagorny, S.; Rowe, E.

    2017-10-01

    The results of investigation into cesium hafnium chloride (Cs2HfCl6) scintillating crystals as a promising detector to search for rare nuclear processes occurring in Hf isotopes is reported. The light output, quenching factor, and pulse-shape characteristics have been investigated at room temperature. The scintillation response of the crystal induced by α-particles and γ-quanta were studied to determine possibility of particle discrimination. Using the optimal filter method we obtained clear separation between signals with a factor of merit (FOM) = 9.3. This indicates that we are able to fully separate signals originating from α-particles and γ-quanta. Similar fruitful discrimination power was obtained by applying the mean time method (FOM = 7) and charge integration method (FOM = 7.5). The quenching factor for collimated 4 MeV α-particles is found to be 0.36, showing that α-particles generate more than a third of the light compared to γ-quanta at the same energy.

  18. HF Radar observations of the Dardanelles outflow current in North Eastern Aegean using validated WERA HF radar data

    Directory of Open Access Journals (Sweden)

    Z. KOKKINI

    2015-01-01

    Full Text Available A two-site WERA HF radar station was installed in November 2009 at the eastern coast of Lemnos Island in North Aegean Sea, aiming to monitor the surface inflow of Black Sea waters exiting from the Dardanelles Strait, as well as to constitute a coastal management tool for incidents of oil-pollution or save-and-rescue operations. Strong interference by foreign transmissions is a source of noise deteriorating the quality of the backscattered signal, thus significantly reducing the HF radar’s effective data return rate. In order to ameliorate this problem, further quality-control and data gap interpolating procedures have been developed and applied, to be used in addition to the procedures incorporated and used by the manufacturer’s signal processing software. The second-level processing involves traditional despiking in the temporal domain, preceding Empirical Orthogonal Function analysis. The latter is used not only to filter high-frequency noise but also to fill data gaps in time and space. The data reconstruction procedure has been assessed via comparison of (a HF radial with CODE-type drifter radial velocities as well as (b HF-derived virtual drifter tracks with actual drifter tracks. The main circulation features and their variability, as revealed by the reconstructed fields, are presented.

  19. HF Radar observations of the Dardanelles outflow current in North Eastern Aegean using validated WERA HF radar data

    Directory of Open Access Journals (Sweden)

    Z. KOKKINI

    2014-12-01

    Full Text Available A two-site WERA HF radar station was installed in November 2009 at the eastern coast of Lemnos Island in North Aegean Sea, aiming to monitor the surface inflow of Black Sea waters exiting from the Dardanelles Strait, as well as to constitute a coastal management tool for incidents of oil-pollution or save-and-rescue operations. Strong interference by foreign transmissions is a source of noise deteriorating the quality of the backscattered signal, thus significantly reducing the HF radar’s effective data return rate. In order to ameliorate this problem, further quality-control and data gap interpolating procedures have been developed and applied, to be used in addition to the procedures incorporated and used by the manufacturer’s signal processing software. The second-level processing involves traditional despiking in the temporal domain, preceding Empirical Orthogonal Function analysis. The latter is used not only to filter high-frequency noise but also to fill data gaps in time and space. The data reconstruction procedure has been assessed via comparison of (a HF radial with CODE-type drifter radial velocities as well as (b HF-derived virtual drifter tracks with actual drifter tracks. The main circulation features and their variability, as revealed by the reconstructed fields, are presented.

  20. The stability of the bifluoride ion (HF - 2) in the gas phase

    Science.gov (United States)

    Heni, Martin; Illenberger, Eugen

    1985-12-01

    The bifluoride ion (HF-2) has been generated by dissociative electron attachment to trans-1,2-difluorethylene and cis-1,2-difluoroethylene. Evaluation of the energetics for these reactions leads to ΔH0f (HF-2) ≤-6.9 eV and E. A. (HF2)≥4.8 eV.

  1. Photon strength function in the Hf-181 nucleus by method of two-step cascade

    CERN Document Server

    Le Hong Khiem

    2003-01-01

    The applicability of sum-coincidence measurements of two-step cascade gamma ray spectra determining Photon Strength Function (PSF) of Hf-181 induced from Hf-180 (n,2 gamma) Hf-181 reaction is presented. Up to 80% intensity of the primary gamma ray transitions in a wide energy range have been deduced and compared to model calculation.

  2. Suppression Factor of ~(182)W for ~(182)Hf AMS at CIAE

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Suppression factor of 182W is an important index in the measurement of 182Hf with AMS method. This factor is defined as the value of 182W/180Hf in blank samples divised by the measured value of 182 W/180Hf with AMS method. In order to satisfy a

  3. 40 CFR 180.1273 - Beauveria bassiana HF23; exemption from the requirement of a tolerance.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Beauveria bassiana HF23; exemption... FOOD Exemptions From Tolerances § 180.1273 Beauveria bassiana HF23; exemption from the requirement of a tolerance. Residues of Beauveria bassiana HF23 are exempt from the requirement of a tolerance on all...

  4. Comparison the percentage of detection of periarthritis in patients with rheumatoid arthritis using clinical examination or ultrasound methods

    Science.gov (United States)

    Karimzadeh, Hadi; Seyedbonakdar, Zahra; Mousavi, Maryam; Karami, Mehdi

    2016-01-01

    Background: This study aimed to compare the percentage of detection of periarthritis in patients with rheumatoid arthritis using clinical examination and ultrasound methods. Materials and Methods: This study is a cross-sectional study which was conducted in Al-Zahra Hospital (Isfahan, Iran) during 2014–2015. In our study, ninety patients were selected based on the American College of Rheumatology 2010 criteria. All patients were examined by a rheumatologist to find the existence of effusion, and the data were filled in the checklist. The ultrasonography for detecting effusion in periarticular structures was done by an expert radiologist with two methods, including high-resolution ultrasonography and power Doppler. The percentage of effusion existence found by physical examination was compared by sonography, and the Chi-square and t-tests were used for data analysis. Results: The percentage of effusion found in areas with physical examination by rheumatologist was lower than the frequency distribution of effusions found by sonography (8.3% VS 14.2%) (P elbow (4 cases), tennis elbow (4 cases), trochanteric bursitis (6 cases), anserine bursitis (6 cases), prepatellar bursitis (11 cases), and ankle tendonitis (7 cases). Tenderness on physical examination was found in 15% of the cases, and the evidence of periarthritis was found in 21/7% through sonography (P < 0.001) and 34% through Doppler sonography (P < 0.001). Conclusion: The percentage of periarthritis detection by ultrasonography and power Doppler sonography was higher than clinical examination. Hence, the ultrasonography is more accurate than physical examination. PMID:28331520

  5. Comparison the percentage of detection of periarthritis in patients with rheumatoid arthritis using clinical examination or ultrasound methods

    Directory of Open Access Journals (Sweden)

    Hadi Karimzadeh

    2016-01-01

    Full Text Available Background: This study aimed to compare the percentage of detection of periarthritis in patients with rheumatoid arthritis using clinical examination and ultrasound methods. Materials and Methods: This study is a cross-sectional study which was conducted in Al-Zahra Hospital (Isfahan, Iran during 2014–2015. In our study, ninety patients were selected based on the American College of Rheumatology 2010 criteria. All patients were examined by a rheumatologist to find the existence of effusion, and the data were filled in the checklist. The ultrasonography for detecting effusion in periarticular structures was done by an expert radiologist with two methods, including high-resolution ultrasonography and power Doppler. The percentage of effusion existence found by physical examination was compared by sonography, and the Chi-square and t-tests were used for data analysis. Results: The percentage of effusion found in areas with physical examination by rheumatologist was lower than the frequency distribution of effusions found by sonography (8.3% VS 14.2% (P < 0.001. In sonography, rotator cuff tendonitis is the most common periarthritis. Other findings in sonography were biceps tendinitis (10 cases, wrist tendonitis (13 cases, olecranon bursitis (9 cases, golfers elbow (4 cases, tennis elbow (4 cases, trochanteric bursitis (6 cases, anserine bursitis (6 cases, prepatellar bursitis (11 cases, and ankle tendonitis (7 cases. Tenderness on physical examination was found in 15% of the cases, and the evidence of periarthritis was found in 21/7% through sonography (P < 0.001 and 34% through Doppler sonography (P < 0.001. Conclusion: The percentage of periarthritis detection by ultrasonography and power Doppler sonography was higher than clinical examination. Hence, the ultrasonography is more accurate than physical examination.

  6. Two-dimensional semiconductor HfSe{sub 2} and MoSe{sub 2}/HfSe{sub 2} van der Waals heterostructures by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Aretouli, K. E.; Tsipas, P.; Tsoutsou, D.; Marquez-Velasco, J.; Xenogiannopoulou, E.; Giamini, S. A.; Vassalou, E.; Kelaidis, N.; Dimoulas, A., E-mail: a.dimoulas@inn.demokritos.gr [Institute of Nanoscience and Nanotechnology, National Center for Scientific Research “Demokritos,” 15310, Aghia Paraskevi, Athens (Greece)

    2015-04-06

    Using molecular beam epitaxy, atomically thin 2D semiconductor HfSe{sub 2} and MoSe{sub 2}/HfSe{sub 2} van der Waals heterostructures are grown on AlN(0001)/Si(111) substrates. Details of the electronic band structure of HfSe{sub 2} are imaged by in-situ angle resolved photoelectron spectroscopy indicating a high quality epitaxial layer. High-resolution surface tunneling microscopy supported by first principles calculations provides evidence of an ordered Se adlayer, which may be responsible for a reduction of the measured workfunction of HfSe{sub 2} compared to theoretical predictions. The latter reduction minimizes the workfunction difference between the HfSe{sub 2} and MoSe{sub 2} layers resulting in a small valence band offset of only 0.13 eV at the MoSe{sub 2}/HfSe{sub 2} heterointerface and a weak type II band alignment.

  7. Stability Analysis of a Constant Power Load Serviced by a Buck Converter as the Source Impedance Varies

    Science.gov (United States)

    2012-09-01

    electric ships, being aware of the stability issues associated with direct current (DC)-DC and DC-alternating current (AC) power converters and... Electric vehicles FCV Fuel Cell Vehicle HEV Hybrid Electric Vehicle Hf Final Load Transfer Function Hf_vec Final Load Transfer Function...Voltage Law SL Source Inductance MEV More Electric Vehicle MVDC Medium Voltage DC xiv P Power OP Output Power Pof Final Power Level Poi

  8. EEG beta power and heart rate variability describe the association between cortical and autonomic arousals across sleep.

    Science.gov (United States)

    Kuo, Terry B J; Chen, Chun-Yu; Hsu, Ya-Chuan; Yang, Cheryl C H

    2016-01-01

    Cortical and autonomic arousals have been found to be closely associated. As arousal events are not evenly dispersed across sleep, we hypothesized the relationship between high frequency electroencephalogram (EEG) power and autonomic arousal indices differ between non-rapid eye movement (NREM) and rapid eye movement (REM) sleep. One night of polysomnographic recording was performed on a group of 18 subjects using a portable recorder. The EEG was collected from C3/Fz. Sleep stages and cortical arousals were visually scored. Cardiac autonomic modulation was assessed from heart rate variability, where the high frequency power (HF) indicates parasympathetic modulation, and the low frequency to high frequency power ratio (LF/HF) represents sympathetic modulation. During NREM sleep, EEG beta power was significantly correlated with LF/HF (r=0.40 ± 0.06), and the relationships were more positive than during REM sleep (LF/HF: r=0.20 ± 0.08; EOG power: r=-0.13 ± 0.05). The relationship of beta power with LF/HF was associated with the incidence of cortical arousal, particularly during NREM sleep. With respect to alpha power, it was only marginally related to HF or LF/HF. In addition, the coefficients of determination were lower for alpha power than for beta power in terms of the relationships to HF, LF/HF and EOG power. This study shows a higher relationship between cortical and autonomic activation during NREM sleep, and the association is better described by beta power. This finding suggests NREM sleep may be of greater therapeutic potential in view of reducing cardiovascular disease associated with sleep fragmentation, and beta power may provide a better index to evaluate the effect.

  9. Wave parameters comparisons between High Frequency (HF) radar system and an in situ buoy: a case study

    Science.gov (United States)

    Fernandes, Maria; Alonso-Martirena, Andrés; Agostinho, Pedro; Sanchez, Jorge; Ferrer, Macu; Fernandes, Carlos

    2015-04-01

    The coastal zone is an important area for the development of maritime countries, either in terms of recreation, energy exploitation, weather forecasting or national security. Field measurements are in the basis of understanding how coastal and oceanic processes occur. Most processes occur over long timescales and over large spatial ranges, like the variation of mean sea level. These processes also involve a variety of factors such as waves, winds, tides, storm surges, currents, etc., that cause huge interference on such phenomena. Measurement of waves have been carried out using different techniques. The instruments used to measure wave parameters can be very different, i.e. buoys, ship base equipment like sonar and satellites. Each equipment has its own advantage and disadvantage depending on the study subject. The purpose of this study is to evaluate the behaviour of a different technology available and presently adopted in wave measurement. In the past few years the measurement of waves using High Frequency (HF) Radars has had several developments. Such a method is already established as a powerful tool for measuring the pattern of surface current, but its use in wave measurements, especially in the dual arrangement is recent. Measurement of the backscatter of HF radar wave provides the raw dataset which is analyzed to give directional data of surface elevation at each range cell. Buoys and radars have advantages, disadvantages and its accuracy is discussed in this presentation. A major advantage with HF radar systems is that they are unaffected by weather, clouds or changing ocean conditions. The HF radar system is a very useful tool for the measurement of waves over a wide area with real-time observation, but it still lacks a method to check its accuracy. The primary goal of this study was to show how the HF radar system responds to high energetic variations when compared to wave buoy data. The bulk wave parameters used (significant wave height, period and

  10. Charge storage characteristics and tunneling mechanism of amorphous Ge-doped HfOx films

    Science.gov (United States)

    Qiu, X. Y.; Zhang, S. Y.; Zhang, T.; Wang, R. X.; Li, L. T.; Zhang, Y.; Dai, J. Y.

    2016-09-01

    Amorphous Ge-doped HfOx films have been deposited on p-Si(100) substrates by means of RF magnetron sputtering. Microstructural investigations reveal the partial oxidation of doped Ge atoms in the amorphous HfOx matrix and the existence of HfSiOx interfacial layer. Capacitance-voltage hysteresis of the Ag-/Ge-doped HfOx/Si/Ag memory capacitor exhibits a memory window of 3.15 V which can maintain for >5 × 104 cycles. Current-voltage characteristics reveal that Poole-Frenkel tunneling is responsible for electron transport in the Ge-doped HfOx film.

  11. HfO2/SiO2 multilayer based reflective and transmissive optics from the IR to the UV

    Science.gov (United States)

    Wang, Jue; Hart, Gary A.; Oudard, Jean Francois; Wamboldt, Leonard; Roy, Brian P.

    2016-05-01

    HfO2/SiO2 multilayer based reflective optics enable threat detection in the short-wave/middle-wave infrared and high power laser targeting capability in the near infrared. On the other hand, HfO2/SiO2 multilayer based transmissive optics empower early missile warning by taking advantage of the extremely low noise light detection in the deep-ultraviolet region where solar irradiation is strongly absorbed by the ozone layer of the earth's atmosphere. The former requires high laser damage resistance, whereas the latter needs a solar-blind property, i.e., high transmission of the radiation below 290 nm and strong suppression of the solar background from 300 nm above. The technical challenges in both cases are revealed. The spectral limits associated with the HfO2 and SiO2 films are discussed and design concepts are schematically illustrated. Spectral performances are realized for potential A and D and commercial applications.

  12. Clinical trials update from the Heart Failure Society of America Meeting 2009: FAST, IMPROVE-HF, COACH galectin-3 substudy, HF-ACTION nuclear substudy, DAD-HF, and MARVEL-1.

    Science.gov (United States)

    Lainscak, Mitja; Coletta, Alison P; Sherwi, Nasser; Cleland, John G F

    2010-02-01

    This article presents findings and a commentary on late-breaking trials presented during the meeting of the Heart Failure Society of America in September 2009. Unpublished reports should be considered as preliminary, since analyses may change in the final publication. The FAST trial showed somewhat better performance of intrathoracic impedance for prediction of deterioration in patients with heart failure (HF) when compared with daily weighing. The IMPROVE-HF study reported the benefits of education on the management of patients with systolic HF. Galectin-3 appeared a useful method for improving risk stratification of patients with chronic HF in a substudy of the COACH trial. A nuclear substudy of the HF-ACTION trial failed to demonstrate that resting myocardial perfusion imaging, a measure of myocardial scar and viability, was clinically useful. A small randomized controlled trial (DAD-HF) suggested that the use of low-dose dopamine in patients with acutely decompensated HF was associated with less deterioration in renal function and less hypokalaemia. The MARVEL-1 trial raises further concerns about the safety of myoblast transplantation in ischaemic HF.

  13. A classification of spectral populations observed in HF radar backscatter from the E region auroral electrojets

    Directory of Open Access Journals (Sweden)

    S. E. Milan

    Full Text Available Observations of HF radar backscatter from the auroral electrojet E region indicate the presence of five major spectral populations, as opposed to the two predominant spectral populations, types I and II, observed in the VHF regime. The Doppler shift, spectral width, backscatter power, and flow angle dependencies of these five populations are investigated and described. Two of these populations are identified with type I and type II spectral classes, and hence, are thought to be generated by the two-stream and gradient drift instabilities, respectively. The remaining three populations occur over a range of velocities which can greatly exceed the ion acoustic speed, the usual limiting velocity in VHF radar observations of the E region. The generation of these spectral populations is discussed in terms of electron density gradients in the electrojet region and recent non-linear theories of E region irregularity generation.

    Key words. Ionosphere (ionospheric irregularities

  14. The anisotropy of Hf diffusion in {alpha}-Zr

    Energy Technology Data Exchange (ETDEWEB)

    Hood, G.M. [Atomic Energy of Canada Ltd., Chalk River, ON (Canada). Chalk River Nuclear Labs.]|[Metals Technology Laboratory, CANMET, Ottawa, Ontario (Canada); Zou, H. [Atomic Energy of Canada Ltd., Chalk River, ON (Canada). Chalk River Nuclear Labs.]|[Metals Technology Laboratory, CANMET, Ottawa, Ontario (Canada); Roy, J.A. [Atomic Energy of Canada Ltd., Chalk River, ON (Canada). Chalk River Nuclear Labs.]|[Metals Technology Laboratory, CANMET, Ottawa, Ontario (Canada); Schultz, R.J. [Atomic Energy of Canada Ltd., Chalk River, ON (Canada). Chalk River Nuclear Labs.]|[Metals Technology Laboratory, CANMET, Ottawa, Ontario (Canada); Matsuura, N. [Atomic Energy of Canada Ltd., Chalk River, ON (Canada). Chalk River Nuclear Labs.]|[Metals Technology Laboratory, CANMET, Ottawa, Ontario (Canada); Jackman, J.A. [Atomic Energy of Canada Ltd., Chalk River, ON (Canada). Chalk River Nuclear Labs.]|[Metals Technology Laboratory, CANMET, Ottawa, Ontario (Canada)

    1996-02-01

    Hf diffusion coefficients (D) have been measured ({proportional_to}870-1100 K) in directions parallel (D{sub pa}) and perpendicular (D{sub pe}) to the c-axis of double-faced, single-crystal specimens of both high purity (HP) and nominally pure (NP) {alpha}-Zr. The diffusion profiles were measured by secondary ion mass spectrometry. Hf diffusion in HP {alpha}-Zr is characterised by an activation energy of about 3.0 eV and a pre-exponential factor of about 10{sup -5} m{sup 2}/s. The anisotropy ratio, D{sub pa}/D{sub pe}, is {proportional_to}<1.0 for the HP specimens and mostly >1.0 for the NP specimens. A dependence of D on diffusion time/depth is indicated for some experiments on NP Zr. (orig.).

  15. Photodetachment of HF-in an Electric Field

    Institute of Scientific and Technical Information of China (English)

    WANG De-Hua

    2008-01-01

    @@ Photdetachment of a negative HF-ion in an electric field is studied by using the two-centre model and the closed orbit theory.An analytic formula is presented for the electron flux of HF- in the presence of an electric field.The results show that the oscillation in the electron flux distribution is caused by the rescattering effect of the molecular ion core and the interference betweed the two nuclei.In addition,the interference between the orbits passing through the given spatial point also plays an important role in the electron flux distribution.This study provides a new understanding of the photodetachment of polar molecules in the presence of external field.

  16. Generation of ionospheric ducts by the HAARP HF heater

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, J A; Pradipta, R; Burton, L M; Labno, A; Lee, M C [Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Watkins, B J; Fallen, C [University of Alaska Fairbanks, Fairbanks, AK 99775 (United States); Kuo, S P [New York University, Brooklyn, NY 11201 (United States); Burke, W J [Air Force Research Laboratory, Hanscom AFB, MA 01731 (United States); Mabius, D; See, B Z, E-mail: mclee@mit.edu [Boston University, Boston, MA 02215 (United States)

    2010-12-15

    We report an investigation of ionospheric ducts having the shape of large plasma sheets, generated by vertically transmitted HAARP HF heater waves in several experiments conducted in Gakona, Alaska. Theory predicts that O-mode heater wave-created ionospheric ducts form parallel-plate waveguides within the meridional plane, and those generated by the X-mode heater waves are orthogonal to the meridional plane. Our theoretical prediction is supported by measurements of ionosonde data (namely ionograms), range-time-intensity (RTI) plots of UHF and HF backscatter radars, as well as magnetometer data analyses. When these plasma sheets experienced ExB drifts, they were intercepted by the HAARP UHF radar and seen as slanted stripes in the RTI plots. This striking feature was also observed in our earlier experiments using the Arecibo UHF radar.

  17. Use of GPS network data for HF Doppler measurements interpretation

    CERN Document Server

    Petrova, Inna R; Latypov, Ruslan R

    2014-01-01

    The method of measurement of Doppler frequency shift of ionospheric signal - HF Doppler technique - is one of well-known and widely used methods of ionosphere research. It allows to research various disturbances in the ionosphere. There are some sources of disturbances in the ionosphere. These are geomagnetic storms, solar flashes, metrological effects, atmospheric waves. This method allows to find out the influence of earthquakes, explosions and other processes on the ionosphere, which occur near to the Earth. HF Doppler technique has the high sensitivity to small frequency variations and the high time resolution, but interpretation of results is difficult. In this work we make an attempt to use GPS data for Doppler measurements interpretation. Modeling of Doppler frequency shift variations with use of TEC allows to separate ionosphere disturbances of medium scale.

  18. Imaging HF-induced large-scale irregularities above HAARP

    Science.gov (United States)

    Djuth, Frank T.; Reinisch, Bodo W.; Kitrosser, David F.; Elder, John H.; Snyder, A. Lee; Sales, Gary S.

    2006-02-01

    The University of Massachusetts-Lowell digisonde is used with the HAARP high-frequency (HF), ionospheric modification facility to obtain radio images of artificially-produced, large-scale, geomagnetic field-aligned irregularities. F region irregularities generated with the HAARP beam pointed in the vertical and geomagnetic field-aligned directions are examined in a smooth background plasma. It is found that limited large-scale irregularity production takes place with vertical transmissions, whereas there is a dramatic increase in the number of source irregularities with the beam pointed parallel to the geomagnetic field. Strong irregularity production appears to be confined to within ~5° of the geomagnetic zenith and does not fill the volume occupied by the HF beam. A similar effect is observed in optical images of artificial airglow.

  19. Performance Analysis of HF Band FB-MC-SS

    Energy Technology Data Exchange (ETDEWEB)

    Hussein Moradi; Stephen Andrew Laraway; Behrouz Farhang-Boroujeny

    2016-01-01

    Abstract—In a recent paper [1] the filter bank multicarrier spread spectrum (FB-MC-SS) waveform was proposed for wideband spread spectrum HF communications. A significant benefit of this waveform is robustness against narrow and partial band interference. Simulation results in [1] demonstrated good performance in a wideband HF channel over a wide range of conditions. In this paper we present a theoretical analysis of the bit error probably for this system. Our analysis tailors the results from [2] where BER performance was analyzed for maximum ration combining systems that accounted for correlation between subcarriers and channel estimation error. Equations are give for BER that closely match the simulated performance in most situations.

  20. Influence of beam parameters on percentage depth dose in electron arc therapy

    Energy Technology Data Exchange (ETDEWEB)

    Pla, M.; Pla, C.; Podgorsak, E.B.

    1988-01-01

    The dependence of rotational or arc electron beam percentage depth doses on the depth of isocenter di and nominal beam field width w is presented. A characteristic angle beta, which uniquely depends on w and di, is defined and the dependence of the radial percentage depth doses on angle beta discussed. It is shown that the characteristic angle beta concept can be used in clinical situations to predict the shape of the percentage depth dose curve when w and di are known, or, more importantly, it can be used to determine the appropriate w when di and the percentage depth dose characteristics are known.

  1. Appeals to AC as a Percentage of Appealable Hearing Level Dispositions

    Data.gov (United States)

    Social Security Administration — Longitudinal report detailing the numbers and percentages of Requests for Review (RR) of hearing level decisions or dismissals filed with the Appeals Council (AC)...

  2. Investigation of new type Cu-Hf-Al bulk glassy alloys

    Science.gov (United States)

    Nagy, E.; Rontó, V.; Sólyom, J.; Roósz, A.

    2009-01-01

    In the last years new type Cu-Hf-Al ternary alloys were developed with high glass forming ability and ductility. The addition of Al to Cu-Hf alloys results in improvements in glass formation, thermal stability and mechanical properties of these alloys. We have investigated new Cu-based bulk amorphous alloys in Cu-Hf-Al ternary system. The alloys with Cu49Hf42Al9, Cu46Hf45Al9, Cu50Hf42.5Al7.5 and Cu50Hf45Al5 compositions were prepared by arc melting. The samples were made by centrifugal casting and were investigated by X-ray diffraction method. Thermodynamic properties were examined by differential scanning calorimetry and the structure of the crystallising phases by scanning electron microscopy. The determination of liquidus temperatures of alloys were measured by differential thermal analysis.

  3. First-principles studies of HF molecule adsorption on intrinsic graphene and Al-doped graphene

    Science.gov (United States)

    Sun, Yuanyuan; Chen, Li; Zhang, Feiwu; Li, Daoyong; Pan, Hongzhe; Ye, Jun

    2010-10-01

    In the search for a high-sensitivity sensor for HF gas, the adsorption of HF molecules on both intrinsic and Al-doped graphene sheets is studied by first-principles calculations. We find that the adsorption mechanisms of HF molecules are different for intrinsic graphene and Al-doped graphene. Al-doped graphene has higher adsorption energy and shorter connecting distance to the HF molecule than intrinsic graphene. The calculated net electron transfers, electronic density difference images and densities of states give evidence that the adsorption of HF molecules on Al-doped graphene is by chemisorption, while there is weak physisorption on intrinsic graphene. Therefore, Al-doped graphene can be expected to have applications as a novel sensor for the detection of HF gas. The HF molecules adsorbed on Al-doped graphene material can be reactivated by applying an external electric field of 0.013 a.u.

  4. Ferroelectric HfO2 for Emerging Ferroelectric Semiconductor Devices

    Science.gov (United States)

    Florent, Karine

    The spontaneous polarization in ferroelectrics (FE) makes them particularly attractive for non-volatile memory and logic applications. Non-volatile FRAM memories using perovskite structure materials, such as Lead Zirconate Titanate (PZT) and Strontium Bismuth Tantalate (SBT) have been studied for many years. However, because of their scaling limit and incompatibility with CMOS beyond 130 nm node, floating gate Flash memory technology has been preferred for manufacturing. The recent discovery of ferroelectricity in doped HfO2 in 2011 has opened the door for new ferroelectric based devices compatible with CMOS technology, such as Ferroelectric Field Effect Transistor (FeFET) and Ferroelectric Tunnel Junctions (FTJ). This work began with developing ferroelectric hysteresis characterization capabilities at RIT. Initially reactively sputtered aluminum doped HfO 2 films were investigated. It was observed that the composition control using co-sputtering was not achievable within the existing capabilities. During the course of this study, collaboration was established with the NaMLab group in Germany to investigate Si doped HfO2 deposited by Atomic Layer Deposition (ALD). Metal Ferroelectric Metal (MFM) devices were fabricated using TiN as the top and bottom electrode with Si:HfO2 thickness ranging from 6.4 nm to 22.9 nm. The devices were electrically tested for P-E, C-V and I-V characteristics. Structural characterizations included TEM, EELS, XRR, XRD and XPS/Auger spectroscopy. Higher remanant polarization (Pr) was observed for films of 9.3 nm and 13.1 nm thickness. Thicker film (22.9 nm) showed smaller Pr. Devices with 6.4 nm thick films exhibit tunneling behavior showing a memristor like I-V characteristics. The tunnel current and ferroelectricity showed decrease with cycling indicating a possible change in either the structure or the domain configurations. Theoretical simulations using the improved FE model were carried out to model the ferroelectric behavior of

  5. Centrifugal stretching of 170Hf in the interacting boson model

    Directory of Open Access Journals (Sweden)

    Werner V.

    2014-03-01

    Full Text Available We present the results of a recent experiment to deduce lifetimes of members of the ground state rotational band of 170Hf, which show the effect of centrifugal stretching in this deformed isotope. Results are compared to the geometrical confined beta-soft(CBS rotor model, as well as to the interacting boson model (IBM. Two methods to correct for effects due to the finite valence space within the IBM are proposed.

  6. Electrochemical characterization of cast Ti-Hf binary alloys.

    Science.gov (United States)

    Cai, Z; Koike, M; Sato, H; Brezner, M; Guo, Q; Komatsu, M; Okuno, O; Okabe, T

    2005-05-01

    This study characterized the electrochemical behavior of Ti-Hf binary alloys in a simulated oral environment. Ti-Hf alloys (10, 20, 25, 30, 35 and 40 mass% Hf) were prepared by arc-melting titanium sponge and hafnium sponge. Specimens of each alloy (n = 4) were prepared using a dental titanium casting system with a MgO-based investment. Specimens were inspected with X-ray radiography to ensure minimal internal porosity. Castings (n = 4) made from pure titanium and commercially pure titanium were used as controls. The ground flat surface (10 mm x 10 mm) on each specimen where approximately 30 microm was removed was used for the characterization. Sixteen-hour open-circuit potential (OCP) measurement, linear polarization and potentiodynamic cathodic polarization were performed sequentially in aerated (air + 10% CO2) MTZ synthetic saliva at 37 degrees C. Potentiodynamic anodic polarization was conducted in the same medium but deaerated (N2 + 10% CO2) 2 h before and during testing. Polarization resistance (R(P)) and Tafel slopes were determined, as were corrosion current density (I(CORR)) and passive current density (I(PASS)). Results were subjected to nonparametric statistical analysis (alpha = 0.05). The OCP stabilized (mean values -229 mV to -470 mV vs. SCE) for all specimens after the 16-h immersion. Similar passivation was observed for all the metals on their anodic polarization diagrams. The Kruskal-Wallis test showed significant differences in OCP among the test groups (p = 0.006). No significant differences were found in R(P), I(CORR) or I(PASS) among all the metals (p>0.3). Results indicate that the electrochemical behavior of the Ti-Hf alloys examined resembles that of pure titanium.

  7. Self-healing structural properties of thermoplastics in HF field

    Directory of Open Access Journals (Sweden)

    N. G. Filippenko

    2014-01-01

    Full Text Available The article concerns one of the possible ways for safe operation of polymer products with initiating a process of their self-healing. This is especially true for products from polymer materials, used in hard-to-reach areas and units of machines and mechanisms. In this regard, the aim of this study was to develop techniques for a self-healing process of the mechanical properties of products from polymer materials.To achieve this goal, the author has solved problems to define a complex method of HF self-healing of polymer material: damage detection in products from polymer materials, determination of signal initiating the recovery process, determining the efficiency of material regeneration. The present study uses proposed and developed by the author methods for the determination of necessary and sufficient indicators of the strength characteristics of products under realmeteorological and climatic conditions of their operation.To determine the practical results of the developed algorithm for self-healing the polymer products in the HF field, a series of experimental studies has been conducted to regenerate the polyamide cage fatigue destruction of the rolling stock axle equipment of Russian Railways JSC.The obtained results of the strength characteristics of the material under investigation prove the self-healing process of polymer materials in HF field.According to research results, the conclusion is drawn that it is required to provide a technological HF self-healing process of products from polymer materials. The created algorithm of regeneration enables a new approach to study the effects of electromagnetic fields on polymer and polymer-based composite materials when solving the practical tasks to improve the quality of repairing parts from thermoplastics.

  8. Hf--Co--B alloys as permanent magnet materials

    Science.gov (United States)

    McGuire, Michael Alan; Rios, Orlando; Ghimire, Nirmal Jeevi

    2017-01-24

    An alloy composition is composed essentially of Hf.sub.2-XZr.sub.XCo.sub.11B.sub.Y, wherein 0B.sub.Y, wherein 0.ltoreq.X<2 and 0

  9. Study on Preparation of 182Hf AMS Standards

    Institute of Scientific and Technical Information of China (English)

    YINXin-yi; JIANGShan; HEMing; ZHANGChun-hua; ZHANGSheng-dong

    2003-01-01

    The neutron-rich isotope 182Hf with its half-life of (9±2)×106 a produced by neutron activation can be used to determine the neutron flux of some places, in order to study the transport of radioactive nuclides and the safe disposal of nuclear waste. AMS is a kind of relative measurement method with high sensitivity (10-15), it requires corresponding standard samples.

  10. On the Onset of HF-Induced Airglow at HAARP

    Science.gov (United States)

    2007-11-02

    AFRL-VS-HA-TR-2005-1061 JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 109, A02305, doi:10.1029/2003JA010205, 2004 On the onset of HF-induced airglow at HAARP ...line) during the February 2002 campaign at the High Frequency Active Auroral Research Program ( HAARP ) heating facility are analyzed. We find that... HAARP , J. Geophys. Res., 109, A02305, doi: 10.1029/2003JA010205. 1. Introduction known as the parametric decay (PDI) or oscillating two- [2] A

  11. HF Over-the-Horizon Radar System Performance Analysis

    Science.gov (United States)

    2007-09-01

    target detection technique and radar equations are applied. Chapter V uses PROPLAB model simulation to bring in the principle of raytracing and... RADAR SYSTEM PERFORMANCE ANALYSIS by Bin-Yi Liu September 2007 Thesis Co-Advisors: Phillip E. Pace Jeffrey B. Knorr THIS PAGE...Thesis 4. TITLE AND SUBTITLE HF Over-the-Horizon Radar System Performance Analysis 6. AUTHOR(S) Bin-Yi Liu 5. FUNDING NUMBERS 7. PERFORMING

  12. Wideband high frequency (HF) skywave channel parameters from narrowband measurements

    Science.gov (United States)

    Hausman, Cynthia L.; Uffelman, Donald R.; Walton, Thomas L.

    The HF wideband channel allow the use of spread-spectrum techniques to provide covert communications with low probability of intercept (LPI) and antijam protection. The objective of this work is to determine the extent to which oblique narrowband channel measurements can be used to infer effects in the wideband skywave channel. If oblique narrowband channel measurements can be used as a basis for developing wideband channel models, a large number of existing narrowband measurements can be made available for this task.

  13. Detection of HCl and HF by TTFMS and WMS.

    Science.gov (United States)

    De Luca, Anna Chiara; Pesce, Giuseppe; Rusciano, Giulia; Sasso, Antonio

    2006-04-01

    In this work we discuss on a compact spectrometer based on DFB diode lasers for detection of chloridric and fluoridric acids. HCl and HF concentrations are determined through optical absorption of the P(4) line (lambda=1.7 microm) and the R(3) line (lambda=1.3 microm), respectively. Both lines belong to first overtone vibrational bands and their line strengths are 7.8 x 10(-21)cm/molecule for HCl and 2.8 x 10(-20)cm/molecule for HF. We chose these lines for their relative high intensities and because they are quite far from water vapour lines which represent the main interfering gas for trace-gases analysis. To detect these species we used two different high frequency modulation techniques: two-tone frequency modulation spectroscopy (f(1)=800 MHz and f(2)=804 MHz) was used for HCl while for HF we followed a simpler approach based on wavelength modulation spectroscopy (f=600 kHz). We demonstrate that the two techniques provide comparable detection limit of about 80 ppbV at atmospheric pressure. Positive testing of our spectrometer makes it suitable for in situ measurements of exhaust gases coming from waste incinerators.

  14. Multiple excitation modes in 163Hf

    DEFF Research Database (Denmark)

    Yadav, Rachita; Ma, J.C.; Marsh, J.C.

    2014-01-01

    Excited states of Hf163 were populated using the Zr94(Ge74,5n) reaction and the decay γ rays were measured with the Gammasphere spectrometer. Two previously known bands were extended to higher spins, and nine new bands were identified. In addition to bands associated with three- and five-quasipar......Excited states of Hf163 were populated using the Zr94(Ge74,5n) reaction and the decay γ rays were measured with the Gammasphere spectrometer. Two previously known bands were extended to higher spins, and nine new bands were identified. In addition to bands associated with three- and five......-quasiparticle configurations, two γ−vibrational bands coupled to the i13/2 excitation were also observed. The lowest level of a newly identified, negative-parity band is proposed to be the ground state of the nucleus. A systematic delay of the high-spin proton crossing frequency with increasing quadrupole deformation from Hf...

  15. Electronic structures and properties of Ti, Zr and Hf metals

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The electronic structures of pure Ti, Zr and Hf metals with hcp structure were determined by one-atom (OA) theory. According to the electronic structures of these metals,their potential curves, cohesive energies, lattice constants, elasticities and the temperature dependence of linear thermal expansion coefficients were calculated. The electronic structures and characteristic properties of these metals with bcc and fcc structures and liquids were also studied. The results show that the electronic structures of Ti, Zr and Hf metals are respectively [Ar](3dn)0.481 0(3dc)2.085 7(4sc)1.000 0(4sf)0.433 3, [Kr](4dn)0.396 8(4dc)2.142 8(5sc)1.262 0(5sf)0.198 4, [Xe](5dn)0.368 0(5dc)2.041 4(6sc)1.406 6(6sf)0.184 0. It is explained why the pure Ti, Zr and Hf metals with hcp and bcc structures can exist naturally, while those with fcc structure can not.

  16. Lu-Hf and Sm-Nd garnet geochronology

    DEFF Research Database (Denmark)

    Smit, Matthijs Arjen; Scherer, Erik E.; Mezger, Klaus

    2013-01-01

    are similar among grains having radii larger than 1.3 mm (weighted mean: 2714±6 Ma2714±6 Ma; 2 s.d.) and up to 20 Myr younger for finer fractions. In contrast, Sm–Nd dates are equal to or younger than the 2641–2637 Ma age of peak metamorphism. The roles of concurrently digested inclusions and core–rim Lu......To investigate the systematics of the 176Lu–176Hf and 147Sm–143Nd garnet chronometers, we performed REE and isotope analyses on garnet crystals of different size (0.55–3.1 mm radius) from a single granulite specimen (Archean Pikwitonei Granulite Domain, Manitoba, Canada). The Lu–Hf dates....../Sm fractionation are quantitatively evaluated and excluded as causes for the observed age heterogeneity. Instead, the isotope dates are interpreted to reflect partial loss of radiogenic 176Hf and 143Nd, and are used to constrain the systematics of the garnet chronometers at high temperature. The data constrain...

  17. TID measurement using oblique transmissions of HF pulses

    Science.gov (United States)

    Galkin, Ivan; Reinisch, Bodo; Huang, Xueqin; Paznukhov, Vadym; Hamel, Ryan; Kozlov, Alexander; Belehaki, Anna

    2017-04-01

    The Traveling Ionospheric Disturbance (TID), a wave-like signature of moving plasma density modulation in the ionosphere, is widely acknowledged for its utility in backtracking the anomalous events responsible for the TID generation, and as a major inconvenience to high-frequency (HF) operational systems because of its deleterious impact on the accuracy of navigation and geolocation. The pilot project "Net-TIDE" for the real-time detection and evaluation of TIDs began its operation in 2016 based on the remote-sensing data from synchronized, network-coordinated HF sounding between pairs of DPS4D ionosondes at five participating observatories in Europe. Measurement of all signal properties (Doppler frequency, angle of arrival, and time-of-flight from transmitter to receiver) proved to be instrumental in detecting the TID and deducing the TID parameters: amplitude, wavelength, phase velocity, and direction of propagation. Processing of the measured HF signal data required a specialized signal processing technique that is capable of consistently extracting different signals that have propagated along different ionospheric paths. The multi-path signal environment proved to be the greatest challenge for the reliable TID specification by Net-TIDE, demanding the development of an intelligent system for "signal tracking". The intelligent system is based on a neural network model of a pre-attentive vision capable of extracting continuous signal tracks from the multi-path signal ensemble. Specific examples of the Net-TIDE algorithm suite operation and its suitability for a fully automated TID warning service are discussed.

  18. High-spin positive-parity states in 179Hf studied by the 180Hf(τ, α) 179Hf reaction AT 32 MeV

    Science.gov (United States)

    Thorsteinsen, T. F.; Løvhøiden, G.; Vaagen, J. S.; Bjørnberg, A.; Burke, D. G.

    1981-06-01

    Full angular distributions are presented for states populated in the reaction 180Hf(τ, α) 179Hf at 32 MeV beam energy. Positive-parity states associated with the i {13}/{2} unique parity intruder orbital are given special attention. Thus, angular distributions for the five first members of the [624 {9}/{2}] groundstate sequence are given, as well as for a number of more highly excited states, some being new assignments. The distribution of l = 6 transfer strength is quite characteristic, two {13}/{2}+ states being substantially more populated than the rest. The characteristic features of the data are explained by a quasiparticle-rotor calculation employing deformed Woods-Saxon orbitals, but only if the hexadecapole shape parameter of the nuclear potential is β 4 ˜ -0.08. The often anomalous differential cross sections for I π ≠ {13}/{2}+ band members are well accounted for by a rotor model CCBA calculation employing transfer form factors extracted from the orbitals of the deformed Woods-Saxon field, and including non-adiabatic Coriolis mixing effects.

  19. Hf isotopic compositions of the standard zircons for U-Pb dating

    Institute of Scientific and Technical Information of China (English)

    XU Ping; WU Fuyuan; XIE Liewen; YANG Yueheng

    2004-01-01

    Using the newly published Yb isotopic abundances and the mass bias relationship between Yb and Hf, we carried out an analysis of Hf isotopes in the standard zircon 91500 by means of 193 nm laser attached to Neptune multi-collector ICP-MS (LA-MC-ICPMS). The obtained Hf isotopic data, in either in situ or line scan modes, are not only identical for different spot sizes, but also are consistent with previously published results obtained on TIMS or other MC-ICPMS machines within errors. This indicates that it is possible to obtain reliable 176Hf/177Hf isotopic ratios for zircon in either in situ or line scan conditions on LA-MC-ICPMS machine, and the applied procedures in our study for elemental interfering correction are appropriate for the purpose of acquiring satisfactory accuracy for Hf isotope analyses. The Hf isotopic compositions of four zircon standards in high spatial resolution U-Pb dating, 91500, CZ3,CN92-1 and TEMORA, are measured, respectively. The obtained 176Hf/177Hf ratios are 0.282316+4 (n = 34, 2σ) for 91500, 0.281704±6 (n = 16, 2σ) for CZ3, 0.282200±6 (n = 20,2σ-) for CN92-1 and 0.282684±14 (n = 24, 2σ) for TEMORA,respectively, with 176Lu/177Hf ratios of ~0.00031, 0.000036,0.00083 and 0.00127. Zircons 91500 and CZ3 show narrower variations in 176Hf/177Hf and 176Lu/177Hf ratios than those of zircons CN92-1 and TEMORA, and thus are appropriate standards for the Hf isotope analysis.

  20. Electrical characteristics of MOS capacitor with HfTiON gate dielectric and HfTiSiON interlayer

    Institute of Scientific and Technical Information of China (English)

    Chen Wei-Bing; Xu Jing-Ping; Lai Pui-To; Li Yan-Ping; Xu Sheng-Guo; Chan Chu-Lok

    2006-01-01

    The paper reports that HfTiO dielectric is deposited by reactive co-sputtering of Hf and Ti targets in an Ar/O2 ambience, followed by an annealing in different gas ambiences of N2, NO and NHa at 600°C for 2 min. Capacitance-voltage and gate-leakage properties are characterized and compared. The results indicate that the NO-annealed sample exhibits the lowest interface-state and dielectric-charge densities and best device reliability. This is attributed to the fact that nitridation can create strong Si≡N bonds to passivate dangling Si bonds and replace strained Si- O bonds, thus the sample forms a hardened dielectric/Si interface with high reliability.

  1. Noise Filter Performance studies for CMS HF by comparing new and old PMTs using Collection of data taken in 2012

    CERN Multimedia

    2016-01-01

    During the data taking before 2012 some abnormal events which have higher signals than expected were observed. Most of these were due to muons. When a muon hits the glass window of photomultiplier tubes (PMTs), it creates a huge signal. To eliminate this kind of events 24 old HF PMTs (Hamamatsu R7525) in HF Minus at iphi 43 (corresponds to one sector) were replaced with new multi anode PMTs (Hamamatsu multi anode R7600) which have thin glass windows. These new PMTs were installed and tested in H2 test beam area in 2009 [1]. To check whether these new PMTs perform better than the old ones, data taken in 2012 were analyzed using various predefined noise filters. The percentage of the noisy rechits was found to be around 6-7 % for the new PMTs while it varies between 29-66 % for the old PMTs for various trigger selections and for HFLongShortFilter after an energy cut of 500 GeV [2]. Presented at 6th Internationally Participated Congress on Particle Accelerators and Applications

  2. The magnetic properties of $^{\\rm 177}$Hf and $^{\\rm 180}$Hf in the strong coupling deformed model

    CERN Document Server

    Muto, S; Bingham, C R; Stone, J R; Walker, P M; Audi, G; Gaulard, C; Köster, U; Nikolov, J; Nishimura, K; Ohtsubo, T; Podolyak, Z; Risegari, L; Simpson, G S; Veskovic, M; Walters, W B

    2014-01-01

    This paper reports NMR measurements of the magnetic dipole moments of two high-K isomers, the 37/2$^-$, 51.4 m, 2740 keV state in $^{\\rm 177}$Hf and the 8$^-$, 5.5 h, 1142 keV state in $^{\\rm 180}$Hf by the method of on-line nuclear orientation. Also included are results on the angular distributions of gamma transitions in the decay of the $^{\\rm 177}$Hf isotope. These yield high precision E2/M1 multipole mixing ratios for transitions in bands built on the 23/2$^+$, 1.1 s, isomer at 1315 keV and on the 9/2$^+$, 0.663 ns, isomer at 321 keV. The new results are discussed in the light of the recently reported finding of systematic dependence of the behavior of the g$_{\\rm R}$ parameter upon the quasi-proton and quasi-neutron make up of high-K isomeric states in this region.

  3. Infants with Down Syndrome: Percentage and Age for Acquisition of Gross Motor Skills

    Science.gov (United States)

    Pereira, Karina; Basso, Renata Pedrolongo; Lindquist, Ana Raquel Rodrigues; da Silva, Louise Gracelli Pereira; Tudella, Eloisa

    2013-01-01

    The literature is bereft of information about the age at which infants with Down syndrome (DS) acquire motor skills and the percentage of infants that do so by the age of 12 months. Therefore, it is necessary to identify the difference in age, in relation to typical infants, at which motor skills were acquired and the percentage of infants with DS…

  4. 42 CFR 420.202 - Determination of ownership or control percentages.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 3 2010-10-01 2010-10-01 false Determination of ownership or control percentages... and Control Information § 420.202 Determination of ownership or control percentages. (a) Indirect... of ownership in each entity. For example, if A owns 10 percent of the stock in a corporation that...

  5. 48 CFR 52.222-31 - Davis-Bacon Act-Price Adjustment (Percentage Method).

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 2 2010-10-01 2010-10-01 false Davis-Bacon Act-Price... Provisions and Clauses 52.222-31 Davis-Bacon Act—Price Adjustment (Percentage Method). As prescribed in 22.407(f), insert the following clause: Davis-Bacon Act—Price Adjustment (Percentage Method) (DEC...

  6. 10 CFR 490.706 - Procedure for modifying the biodiesel component percentage.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 3 2010-01-01 2010-01-01 false Procedure for modifying the biodiesel component percentage... TRANSPORTATION PROGRAM Biodiesel Fuel Use Credit § 490.706 Procedure for modifying the biodiesel component percentage. (a) DOE may, by rule, lower the 20 percent biodiesel volume requirement of this subpart...

  7. 40 CFR 60.483-1 - Alternative standards for valves-allowable percentage of valves leaking.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Alternative standards for valves-allowable percentage of valves leaking. 60.483-1 Section 60.483-1 Protection of Environment ENVIRONMENTAL... Before November 7, 2006 § 60.483-1 Alternative standards for valves—allowable percentage of...

  8. 13 CFR 126.701 - Can these subcontracting percentages requirements change?

    Science.gov (United States)

    2010-01-01

    ... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false Can these subcontracting percentages requirements change? 126.701 Section 126.701 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION HUBZONE PROGRAM Contract Performance Requirements § 126.701 Can these subcontracting percentages...

  9. Polarity reversion of the operation mode of HfO2-based resistive random access memory devices by inserting Hf metal layer.

    Science.gov (United States)

    Peng, Ching-Shiang; Chang, Wen-Yuan; Lin, Ming-Ho; Chen, Wei-Su; Chen, Frederick; Tsai, Ming-Jinn

    2013-03-01

    The reversion of polarity within bipolar resistive switching operation occurs in Pt/HfO2/TiN and Pt/Hf/HfO2/TiN resistive random access memory devices. This reversion of voltage polarity is the result of interface generation which induces a conduction mechanism transformation from Poole-Frenkel emission to space charge limited current mechanism. To prove the reversion of polarity, this study uses curve fitting of I-V relations to verify the conduction mechanism theoretically and physical analysis to verify the oxygen ion distribution practically. The proposed Pt/Hf/HfO2/TiN devices exhibit good resistive switching characteristics, such as good uniformity, low voltage operation, robust endurance (10(3) dc sweep), and long retention (3 x 10(4) s at 85 degrees C).

  10. Vertically oriented few-layered HfS2 nanosheets: growth mechanism and optical properties

    Science.gov (United States)

    Zheng, Binjie; Chen, Yuanfu; Wang, Zegao; Qi, Fei; Huang, Zhishuo; Hao, Xin; Li, Pingjian; Zhang, Wanli; Li, Yanrong

    2016-09-01

    For the first time, large-area, vertically oriented few-layered hafnium disulfide (V-{{{HfS}}}2) nanosheets have been grown by chemical vapor deposition. The individual {{{HfS}}}2 nanosheets are well [001] oriented, with highly crystalline quality. Far different from conventional van der Waals epitaxial growth mechanism for two-dimensional transition metal dichalcogenides, a novel dangling-bond-assisted self-seeding growth mechanism is proposed to describe the growth of V-{{{HfS}}}2 nanosheets: difficult migration of {{{HfS}}}2 adatoms on substrate surface results in {{{HfS}}}2 seeds growing perpendicularly to the substrate; V-{{{HfS}}}2 nanosheets inherit the growth direction of {{{HfS}}}2 seeds; V-{{{HfS}}}2 nanosheets further expand in the in-plane direction with time evolution. Moreover, the V-{{{HfS}}}2 nanosheets show strong and broadened photons absorption from near infrared to ultraviolet; the V-{{{HfS}}}2-based photodetector exhibits an ultrafast photoresponse time of 24 ms, and a high photosensitivity ca. 103 for 405 nm laser.

  11. Empirical Study of the Multiaxial, Thermomechanical Behavior of NiTiHf Shape Memory Alloys

    Science.gov (United States)

    Shukla, Dhwanil; Noebe, Ronald D.; Stebner Aaron P.

    2013-01-01

    An empirical study was conducted to characterize the multiaxial, thermomechanical responses of new high temperature NiTiHf alloys. The experimentation included loading thin walled tube Ni(sub 50.3)Ti(sub 29.7)Hf(sub 20) alloy samples along both proportional and nonproportional axial-torsion paths at different temperatures while measuring surface strains using stereo digital image correlation. A Ni(sub 50.3)Ti(sub 33.7)Hf(sub 16) alloy was also studied in tension and compression to document the effect of slightly depleting the Hf content on the constitutive responses of NiTiHf alloys. Samples of both alloys were made from nearly texture free polycrystalline material processed by hot extrusion. Analysis of the data shows that very small changes in composition significantly alter NiTiHf alloy properties, as the austenite finish (Af) temperature of the 16-at Hf alloy was found to be approximately 60 C less than the 20-at Hf alloy (approximately 120 C vs. 180 C). In addition, the 16-at Hf alloy exhibited smaller compressive transformation strains (2 vs. 2.5 percent). Multi-axial characterization of the 20-at % Hf alloy showed that while the random polycrystal transformation strains in tension (4 percent) and compression (2.5 percent) are modest in comparison with binary NiTi (6 percent, 4 percent), the torsion performance is superior (7 vs. 4 shear strain width to the pseudoelastic plateau).

  12. Signal processing techniques for phase-coded HF-VHF radars

    Directory of Open Access Journals (Sweden)

    J. A. Baskaradas

    2003-06-01

    Full Text Available HF-VHF radar techniques are easy to employ and commonly used in geophysical applications. They include deep radio soundings, used for probing the ionosphere, stratosphere-mesosphere measurement, weather forecast and radio-glaciology. Fast algorithms and powerful processors facilitate the development of several kinds of low power radars, but the reduction of the transmitted power has to be compensated by on-line processing of an encoded signal to maintain a favorable signal-to-noise ratio suitable for detection. Moreover, radars have to reconstruct return echoes with different travel times due to various origins (multi-path, adjacent objects, etc.. Such needs can be accomplished by means of signal phase coding and one of the most attractive is the reversal phase code. The composite echo signal must be processed to extract the physical information useful for the measurement considered. In this paper some algorithms used for on-line processing of phase-coded signals will be described, both in time and frequency domain.

  13. Effects of HfB2 and HfN Additions on the Microstructures and Mechanical Properties of TiB2-Based Ceramic Tool Materials

    Directory of Open Access Journals (Sweden)

    Jing An

    2017-04-01

    Full Text Available The effects of HfB2 and HfN additions on the microstructures and mechanical properties of TiB2-based ceramic tool materials were investigated. The results showed that the HfB2 additive not only can inhibit the TiB2 grain growth but can also change the morphology of some TiB2 grains from bigger polygons to smaller polygons or longer ovals that are advantageous for forming a relatively fine microstructure, and that the HfN additive had a tendency toward agglomeration. The improvement of flexural strength and Vickers hardness of the TiB2-HfB2 ceramics was due to the relatively fine microstructure; the decrease of fracture toughness was ascribed to the formation of a weaker grain boundary strength due to the brittle rim phase and the poor wettability between HfB2 and Ni. The decrease of the flexural strength and Vickers hardness of the TiB2-HfN ceramics was due to the increase of defects such as TiB2 coarse grains and HfN agglomeration; the enhancement of fracture toughness was mainly attributed to the decrease of the pore number and the increase of the rim phase and TiB2 coarse grains. The toughening mechanisms of TiB2-HfB2 ceramics mainly included crack bridging and transgranular fracture, while the toughening mechanisms of TiB2-HfN ceramics mainly included crack deflection, crack bridging, transgranular fracture, and the core-rim structure.

  14. Crystallography of the NiHfSi Phase in a NiAl (0.5 Hf) Single-Crystal Alloy

    Science.gov (United States)

    Garg, A.; Noebe, R. D.; Darolia, R.

    1996-01-01

    Small additions of Hf to conventionally processed NiAl single crystals result in the precipitation of a high density of cuboidal G-phase along with a newly identified silicide phase. Both of these phases form in the presence of Si which is not an intentional alloying addition but is a contaminant resulting from contact with the ceramic shell molds during directional solidification of the single-crystal ingots. The morphology, crystal structure and Orientation Relationship (OR) of the silicide phase in a NiAl (0.5 at.%Hf) single-crystal alloy have been determined using transmission electron microscopy, electron microdiffraction and energy dispersive X-ray spectroscopy. Qualitative elemental analysis and indexing of the electron microdiffraction patterns from the new phase indicate that it is an orthorhombic NiHfSi phase with unit cell parameters, a = 0.639 nm, b = 0.389 nm and c = 0.72 nm, and space group Pnma. The NiHfSi phase forms as thin rectangular plates on NiAl/111/ planes with an OR that is given by NiHfSi(100))(parallel) NiAl(111) and NiHfSi zone axes(010) (parallel) NiAl zone axes (101). Twelve variants of the NiHfSi phase were observed in the alloy and the number of variants and rectangular morphology of NiHfSi plates are consistent with symmetry requirements. Quenching experiments indicate that nucleation of the NiHfSi phase in NiAI(Hf) alloys is aided by the formation of NiAl group of zone axes (111) vacancy loops that form on the NiAl /111/ planes.

  15. An ab initio study of the C2H2-HF, C2H(CH3)-HF and C2(CH3)2-HF hydrogen-bonded complexes.

    Science.gov (United States)

    Ramos, Mozart N; Lopes, Kelson C; Silva, Washington L V; Tavares, Alessandra M; Castriani, Fátima A; do Monte, Silmar A; Ventura, Elizete; Araújo, Regiane C M U

    2006-02-01

    MP2/6-31++G** and B3LYP/6-31++G** ab initio molecular orbital calculations have been performed in order to obtain molecular geometries, binding energies and vibrational properties of the C2H2-HF, C2H(CH3)-HF and C2(CH3)2-HF H-bonded complexes. As expected, the more pronounced effects on the structural properties of the isolated molecules due to complexation was verified for the C[triple bond]C and H-F bond lengths, which are directly involved in the H-bond formation. These bond distances increased after complexation. BSSE uncorrected B3LYP binding energies are always lower than the corresponding MP2 values. However, the opposite trend has been verified after BSSE correction by the counterpoise method since it is much lower at B3LYP than at MP2 level. The binding energies for these complexes as well as for the HF acid submolecule modes (the HF stretching and vibrational frequency modes) showed an increasing hydrogen-bonding strength with increasing methyl substitution. The splitting in the HF in-plane and out-of-plane bending modes reflects the anisotropy in the hydrogen-bonding interaction with the pi system of the C[triple bond]C bond. The H-F stretching frequency is shifted downward after complexation and it increases with the methyl substitution. The IR intensities of the HF acid submolecule fundamentals are adequately interpreted through the atomic polar tensor of the hydrogen atom using the charge-charge flux-overlap model. The skeletal stretching modes of the Alkyne submolecule are decreased in the complex. The new vibrational modes arising from complexation show several interesting features.

  16. The effect of plasma density structure on HF radio wave propagation at auroral and polar latitudes measured by e-POP

    Science.gov (United States)

    Perry, G. W.; James, H. G.; Gillies, R.; McWilliams, K. A.; St-Maurice, J. P.; Yau, A. W.

    2015-12-01

    One of the scientific objectives of the enhanced Polar Outflow Probe (e-POP) Radio Receiver Instrument (RRI) is to study ionospheric density structure and its impact on High Frequency (HF) radio wave propagation. We present a survey of several ePOP RRI transits through isolated beams of the Super Dual Auroral Radar Network (SuperDARN) Saskatoon and Rankin Inlet radars. It reveals that the spreading of a SuperDARN beam beyond its nominal azimuthal beam width of 3.24° is a common occurrence at auroral and polar latitudes. Furthermore, on multiple occasions, lateral deviations of a beam's power peak by several beam widths was measured, indicating the presence of significant plasma density gradients along the ray path. The e-POP RRI measurements illustrate that our understanding and recognition of plasma density gradients and their influence on HF radio wave propagation is limited. We report on the results of employing HF ray tracing techniques to quantify the impact of ionospheric structuring on HF radio wave propagation, and consider the source of the gradients contributing to the spreading of the SuperDARN beams.

  17. A Study of VO2 Max and Body Fat Percentage in Female Athletes

    Science.gov (United States)

    Bute, Smita S; Deshmukh, P.R

    2014-01-01

    Introduction: Aerobic capacity of athletes is an important element of success in sports achievements. It is generally considered the best indicator of cardio respiratory endurance and athletic fitness. Body fat percentage affects VO2 max and thus the cardiovascular status of the athletes. The present study was undertaken to assess the VO2 max and body fat percentage in athletes. The secondary objective of the study was to study the relationship between VO2 max and body fat percentage. Materials and Methods: Twenty five female athletes of age group 17-22years were selected for the study. VO2 max was determined by Queen’s college step test and body fat percentage by skin fold calipers. The VO2 max and body fat percentage were determined in non athletes of same age group for comparison. The statistical analysis was done by Student’s t-test and Pearson correlation test. Observation and Results: The mean VO2 max in athletic group was 39.62 ± 2.80 ml/kg/min. In non-athletic group, VO2 max was 23.54 ± 3.26 ml/kg/min. The mean body fat percentage in athletes was 24.11 ± 1.83% and in non-athletes it was 29.31 ± 3.86%.The difference in VO2 max and body fat percentage was statistically significant in our study. The VO2 max and body fat percentage in both the groups showed negative correlation by Pearson test but, was not statistically significant. Conclusion: The present study showed a statistically significant higher VO2 max in female athletes. The study showed a negative correlation between VO2 max and body fat percentage but was not statistically significant. PMID:25653935

  18. On the etching characteristics and mechanisms of HfO2 thin films in CF4/O2/Ar and CHF3/O2/Ar plasma for nano-devices.

    Science.gov (United States)

    Lim, Nomin; Efremov, Alexander; Yeom, Geun Young; Kwon, Kwang-Ho

    2014-12-01

    The study of etching characteristics and mechanisms for HfO2 and Si in CF4/O2/Ar and CHF3/O2/Ar inductively-coupled plasmas was carried out. The etching rates of HfO2 thin films as well as the HfO2/Si etching selectivities were measured as functions of Ar content in a feed gas (0-50% Ar) at fixed fluorocarbon gas content (50%), gas pressure (6 mTorr), input power (700 W), bias power (200 W), and total gas flow rate (40 sccm). Plasma parameters as well as the differences in plasma chemistries for CF4- and CHF3-based plasmas were analyzed using Langmuir probe diagnostics and 0-dimensional plasma modeling. It was found that, in both gas systems, the non-monotonic (with a maximum at about 15-20% Ar) HfO2 etching rate does not correlate with monotonic changes of F atom flux and ion energy flux. It was proposed that, under the given set of experimental conditions, the HfO2 etching process is affected by the factors determining the formation and decomposition kinetics of the fluorocarbon polymer layer. These factor are the fluxes of CF(x) (x = 1, 2) radicals, O atoms and H atoms.

  19. Coalescence of silver clusters by immersion in diluted HF solution

    Energy Technology Data Exchange (ETDEWEB)

    Milazzo, R. G.; Mio, A. M.; D’Arrigo, G.; Spinella, C. [CNR-IMM Institute for Microelectronics and Microsystems, I-95121 Catania (Italy); Grimaldi, M. G. [Department of Physics and Astronomy, Università di Catania, I-95123 Catania (Italy); MATIS IMM-CNR, I-95123 Catania (Italy); Rimini, E. [CNR-IMM Institute for Microelectronics and Microsystems, I-95121 Catania (Italy); Department of Physics and Astronomy, Università di Catania, I-95123 Catania (Italy)

    2015-07-14

    The galvanic displacement deposition of silver on H-terminated Si (100) in the time scale of seconds is instantaneous and characterized by a cluster density of 10{sup 11}-10{sup 12} cm{sup −2}. The amount of deposited Ag follows a t{sup 1/2} dependence in agreement with a Cottrell diffusion limited mechanism. At the same time, during the deposition, the cluster density reduces by a factor 5. This behavior is in contrast with the assumption of immobile clusters. We show in the present work that coalescence and aggregation occur also in the samples immersed in the diluted hydrofluoric acid (HF) solution without the presence of Ag{sup +}. Clusters agglomerate according to a process of dynamic coalescence, typical of colloids, followed by atomic redistribution at the contact regions with the generation of multiple internal twins and stacking-faults. The normalized size distributions in terms of r/r{sub mean} follow also the prediction of the Smoluchowski ripening mechanism. No variation of the cluster density occurs for samples immersed in pure H{sub 2}O solution. The different behavior might be associated to the strong attraction of clusters to oxide-terminated Si surface in presence of water. The silver clusters are instead weakly bound to hydrophobic H-terminated Si in presence of HF. HF causes then the detachment of clusters and a random movement on the silicon surface with mobility of about 10{sup −13} cm{sup 2}/s. Attractive interaction (probably van der Waals) among particles promotes coarsening.

  20. Strong photoluminescence of the porous silicon with HfO2-filled microcavities

    Science.gov (United States)

    Jiang, Ran; Wu, Zhengran; Du, Xianghao; Han, Zuyin; Sun, Weideng

    2015-06-01

    Greatly enhanced blue emission was observed at room temperature in the single-crystal silicon with HfO2 filled into its microcavities. The broad blue band light was emitted from both the HfO2 dielectric and the porous Si. The ferroelectricity of HfO2 enhances the blue emission from Si by its filling into the microcaivities. At the same time, HfO2 contributes to the light emission for the transitions of the defect levels for oxygen vacancy. The observation of greatly enhanced blue light emission of the porous Si filled with HfO2 dielectric is remarkable as both HfO2 and Si are highly compatible with Si-based electronic industry.

  1. Ozone Treatment Improved the Resistive Switching Uniformity of HfAlO2 Based RRAM Devices

    Directory of Open Access Journals (Sweden)

    Lifeng Liu

    2015-01-01

    Full Text Available HfAlO2 based resistive random access memory (RRAM devices were fabricated using atomic layer deposition by modulating deposition cycles for HfO2 and Al2O3. Effect of ozone treatment on the resistive switching uniformity of HfAlO2 based RRAM devices was investigated. Compared to the as-fabricated devices, the resistive switching uniformity of HfAlO2 based RRAM devices with the ozone treatment is significantly improved. The uniformity improvement of HfAlO2 based RRAM devices is related to changes in compositional and structural properties of the HfAlO2 resistive switching film with the ozone treatment.

  2. Medium-Range Order Structure and Fragility of Superheated Melts of Amorphous CuHf Alloys

    Institute of Scientific and Technical Information of China (English)

    BIAN Xiu-Fang; SUN Bao-An; HU Li-Na

    2006-01-01

    @@ The structural factors of amorphous CuHf alloys at different temperatures are determined by using a high temperature x-ray diffractometer. It is found that not only the short-range order structure but also the medium-range order structure exists in amorphous CuHf alloys. The dynamic viscosities of CuHf alloy melts are measured by a torsional oscillation viscometer. The fragility of superheated melts of CuHf alloys is calculated based on the viscosity data. The experimental results show that the glass-forming ability of the CuHf alloys is closely related to the fragility of their superheated melt. The relationship between the medium-range order structures and the fragility of superheated melts has also been established in amorphous CuHf alloys. In contrast to the fragility of supercooled liquids, the fragility of superheated liquids promises a better approach to reflecting the dynamics of glass forming liquids.

  3. Ionosphere research with a HF/MF cubesat radio instrument

    Science.gov (United States)

    Kallio, Esa; Aikio, Anita; Alho, Markku; Fontell, Mathias; Harri, Ari-Matti; Kauristie, Kirsti; Kestilä, Antti; Koskimaa, Petri; Mäkelä, Jakke; Mäkelä, Miika; Turunen, Esa; Vanhamäki, Heikki; Verronen, Pekka

    2017-04-01

    New technology provides new possibilities to study geospace and 3D ionosphere by using spacecraft and computer simulations. A type of nanosatellites, CubeSats, provide a cost effective possibility to provide in-situ measurements in the ionosphere. Moreover, combined CubeSat observations with ground-based observations gives a new view on auroras and associated electromagnetic phenomena. Especially joint and active CubeSat - ground based observation campaigns enable the possibility of studying the 3D structure of the ionosphere. Furthermore using several CubeSats to form satellite constellations enables much higher temporal resolution. At the same time, increasing computation capacity has made it possible to perform simulations where properties of the ionosphere, such as propagation of the electromagnetic waves in the medium frequency, MF (0.3-3 MHz) and high frequency, HF (3-30 MHz), ranges is based on a 3D ionospheric model and on first-principles modelling. Electromagnetic waves at those frequencies are strongly affected by ionospheric electrons and, consequently, those frequencies can be used for studying the plasma. On the other hand, even if the ionosphere originally enables long-range telecommunication at MF and HF frequencies, the frequent occurrence of spatiotemporal variations in the ionosphere disturbs communication channels, especially at high latitudes. Therefore, study of the MF and HF waves in the ionosphere has both a strong science and technology interests. We introduce recently developed simulation models as well as measuring principles and techniques to investigate the arctic ionosphere by a polar orbiting CubeSat whose novel AM radio instrument measures HF and MF waves. The cubesat, which contains also a white light aurora camera, is planned to be launched in late 2017 (http://www.suomi100satelliitti.fi/eng). The new models are (1) a 3D ray tracing model and (2) a 3D full kinetic electromagnetic simulation. We also introduce how combining of the

  4. A SYNCHRONIZATION ALGORITHM FOR HF (HIGH FREQUENCY) BROADBAND OFDM SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Yang Lei; Zhang You'ai

    2008-01-01

    In this letter, a kind of associated synchronization algorithm which is suitable for HF (High Frequency) broadband OFDM (Orthogonal Frequency Division Multiplexing) system is presented based on describing and constructing the GMW (Gorden, Mills and Welch) sequence. The algorithm is based on the Schmidl and Minn's symbol timing principle, the constructed GMW sequence is transmitted and disposed, and the synchronization is adjudicated using the correlation of GMW sequence. The simulation result indicates that this algorithm has high performance synchronization ability under the low SNR (Signal to Noise Ratio) at two different kinds of channel models.

  5. Meteorite zircon constraints on the bulk Lu-Hf isotope composition and early differentiation of the Earth.

    Science.gov (United States)

    Iizuka, Tsuyoshi; Yamaguchi, Takao; Hibiya, Yuki; Amelin, Yuri

    2015-04-28

    Knowledge of planetary differentiation is crucial for understanding the chemical and thermal evolution of terrestrial planets. The (176)Lu-(176)Hf radioactive decay system has been widely used to constrain the timescales and mechanisms of silicate differentiation on Earth, but the data interpretation requires accurate estimation of Hf isotope evolution of the bulk Earth. Because both Lu and Hf are refractory lithophile elements, the isotope evolution can be potentially extrapolated from the present-day (176)Hf/(177)Hf and (176)Lu/(177)Hf in undifferentiated chondrite meteorites. However, these ratios in chondrites are highly variable due to the metamorphic redistribution of Lu and Hf, making it difficult to ascertain the correct reference values for the bulk Earth. In addition, it has been proposed that chondrites contain excess (176)Hf due to the accelerated decay of (176)Lu resulting from photoexcitation to a short-lived isomer. If so, the paradigm of a chondritic Earth would be invalid for the Lu-Hf system. Herein we report the first, to our knowledge, high-precision Lu-Hf isotope analysis of meteorite crystalline zircon, a mineral that is resistant to metamorphism and has low Lu/Hf. We use the meteorite zircon data to define the Solar System initial (176)Hf/(177)Hf (0.279781 ± 0.000018) and further to identify pristine chondrites that contain no excess (176)Hf and accurately represent the Lu-Hf system of the bulk Earth ((176)Hf/(177)Hf = 0.282793 ± 0.000011; (176)Lu/(177)Hf = 0.0338 ± 0.0001). Our results provide firm evidence that the most primitive Hf in terrestrial zircon reflects the development of a chemically enriched silicate reservoir on Earth as far back as 4.5 billion years ago.

  6. Thermodynamic modeling of the Co–Hf system supported by key experiments and first-principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Xingxu [School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083 (China); State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Liu, Shuhong, E-mail: shhliu@csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Sino-German Cooperation Group “Microstructure in Al alloys”, Central South University, Changsha, Hunan 410083 (China); Cheng, Kaiming; Tang, Ying [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Ou, Pengfei [School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083 (China); State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Nash, Philip [Thermal Processing Technology Center, Illinois Institute of Technology (IIT), 10 West 32nd Street, Chicago, IL 60616 (United States); Sundman, Bo [INSTN, CEA Saclay, 91191 Gif-Sur-Yvette Cedex (France); Du, Yong [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Sino-German Cooperation Group “Microstructure in Al alloys”, Central South University, Changsha, Hunan 410083 (China); Zheng, Feng [School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083 (China)

    2015-05-20

    Highlights: • Heat contents of Co{sub 2}Hf and CoHf{sub 2} were measured by drop calorimetry. • Enthalpy of formation for Co{sub 23}Hf{sub 6} was computed via first-principles calculations. • Co–Hf system was assessed by means of CALPHAD approach. • Order–disorder model is used to describe B2 (CoHf) and A2 (βHf). • Glass forming range of the Co–Hf amorphous alloys was predicted. - Abstract: Phase equilibria and thermodynamic properties of the Co–Hf system were investigated via calorimetric measurements, first-principles calculations and thermodynamic modeling. Heat contents of Co{sub 2}Hf and CoHf{sub 2} were measured by drop calorimetry from 300 to 1200 °C. The enthalpy of formation for Co{sub 23}Hf{sub 6} at 0 K was computed via first-principles calculations. Based on the experimental measurements and first-principles calculations from the present work and the literature, the Co–Hf system was assessed by means of CALPHAD (CALculation of PHAse Diagram) approach. The excess Gibbs energy of solution phases was modeled with Redlich–Kister polynomial. Sublattice models were employed to describe the homogeneity ranges of Co{sub 2}Hf, CoHf and CoHf{sub 2}. The order–disorder transition between B2 (CoHf) and A2 (βHf) phases was taken into account in the current optimization. Using the optimized parameters, glass forming range (GFR) of the Co–Hf amorphous alloys was predicted to be 15–75 at.% Hf, which is in satisfactory agreement with the experimental observation.

  7. Description of $^{178}$Hf$^{m2}$ in the constrained relativistic mean field theory

    CERN Document Server

    Wei, Zhang; Shuang-Quan, Zhang

    2009-01-01

    The properties of the ground state of $^{178}$Hf and the isomeric state $^{178}$Hf$^{m2}$ are studied within the adiabatic and diabatic constrained relativistic mean field (RMF) approaches. The RMF calculations reproduce well the binding energy and the deformation for the ground state of $^{178}$Hf. Using the ground state single-particle eigenvalues obtained in the present calculation, the lowest excitation configuration with $K^\\pi=16^+$ is found to be $\

  8. Assembly of the CMS HF (hadron forward) calorimeter, April 2003 to June 2005

    CERN Multimedia

    Tejinder S. Virdee, CERN

    2005-01-01

    The forward calorimeters (HF) of the CMS hadron calorimeter system are located 11.2 m from the interaction point. Each HF module is composed by 18 wedges, made of steel absorbers and radiation-hard quartz fibers. The photogallery shows the wedges (Figs. 1-3, April 2003), the assembly of one HF module (Figs. 4-9, May and June 2004) and the assembly of the other (Figs. 10-11, June 2005)

  9. Far-Field Testing Method of Spurious Emission Produced by HF RFID

    OpenAIRE

    Nikola Gvozdenovic; Ralph Prestros; Mecklenbräuker, Christoph F.

    2016-01-01

    We present measurements of spurious emission produced by high-frequency radio frequency identification (HF RFID) using carrier frequency of 13.56 MHz. HF RFID tags produce unwanted emission due to rectification and more generally due to nonlinearity of analog front end. Depending on the conducting material of an HF RFID coil and surrounding dielectric material, the coil behaves as more or less good antenna on some harmonic frequencies. Exact characterization and analysis of unwanted emission ...

  10. Enhanced resistive switching and multilevel behavior in bilayered HfAlO/HfAlO{sub x} structures for non-volatile memory applications

    Energy Technology Data Exchange (ETDEWEB)

    Faita, F. L., E-mail: fabriciofaita@gmail.com [Centre of Physics, University of Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Departamento de Física, Universidade Federal de Santa Catarina, Campus Trindade, 88040-900 Florianópolis, SC (Brazil); Silva, J. P. B., E-mail: josesilva@fisica.uminho.pt [Centre of Physics, University of Minho, Campus de Gualtar, 4710-057 Braga (Portugal); IFIMUP and IN-Institute of Nanoscience and Nanotechnology, Departamento de Física e Astronomia, Faculdade de Ciências da Universidade do Porto, 4169-007 Porto (Portugal); Pereira, M.; Gomes, M. J. M. [Centre of Physics, University of Minho, Campus de Gualtar, 4710-057 Braga (Portugal)

    2015-12-14

    In this work, hafnium aluminum oxide (HfAlO) thin films were deposited by ion beam sputtering deposition technique on Si substrate. The presence of oxygen vacancies in the HfAlO{sub x} layer deposited in oxygen deficient environment is evidenced from the photoluminescence spectra. Furthermore, HfAlO(oxygen rich)/HfAlO{sub x}(oxygen poor) bilayer structures exhibit multilevel resistive switching (RS), and the switching ratio becomes more prominent with increasing the HfAlO layer thickness. The bilayer structure with HfAlO/HfAlO{sub x} thickness of 30/40 nm displays the enhanced multilevel resistive switching characteristics, where the high resistance state/intermediate resistance state (IRS) and IRS/low resistance state resistance ratios are ≈10{sup 2} and ≈5 × 10{sup 5}, respectively. The switching mechanisms in the bilayer structures were investigated by the temperature dependence of the three resistance states. This study revealed that the multilevel RS is attributed to the coupling of ionic conduction and the metallic conduction, being the first associated to the formation and rupture of conductive filaments related to oxygen vacancies and the second with the formation of a metallic filament. Moreover, the bilayer structures exhibit good endurance and stability in time.

  11. Effects of varying the percentage of key illuminations paired with food in a positive automaintenance procedure.

    Science.gov (United States)

    Gonzalez, F A

    1974-11-01

    Three pigeons were exposed to a positive automaintenance procedure in which each trial began with a brief tone followed by the transillumination of a small central area of the response key for 10 sec. Key illumination was followed by food on 100%, 50%, 25%, 12.5%, and 0% of the trials. The effects depended on the dependent variable observed. The mean rate of responding during key illumination rapidly increased and then decreased slightly as the percentage of key illuminations paired with food increased. The number of key illuminations during which at least one response occurred increased as a negatively accelerating function of the percentage of key illuminations paired with food, and the mean latency to the first response during the key illuminations decreased as a negatively decelerating function of the percentage condition. The mean rate of sustained responding during key illumination was not systematically affected by changes in the percentage conditions.

  12. Weight Percentage of Calcium Carbonate for 17 Equatorial Pacific Cores from Brown University

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Weight percentages of calcium carbonate in this file were compiled by J. Farrell and W. L. Prell of Brown University for 17 equatorial Pacific Ocean sediment cores....

  13. Ferroelectric phase stabilization of HfO2 by nitrogen doping

    Science.gov (United States)

    Xu, Lun; Nishimura, Tomonori; Shibayama, Shigehisa; Yajima, Takeaki; Migita, Shinji; Toriumi, Akira

    2016-09-01

    We report that nitrogen (N) doping can drive the ferroelectricity of HfO2. It was found that N doping can cause the transition from a monoclinic phase to a highly symmetric phase. The role of N doping is discussed from the viewpoints of charge balance and bond-constraining effects. The former is responsible for the structural transformation from a paraelectric phase to a ferroelectric phase by forming an oxygen vacancy. In addition, Hf-N and N-O bonds with covalent characteristics have strong effects on HfO2 structural and electrical properties, and thus contribute to a marked HfO2 para-/ferroelectric transition.

  14. Efficient noble metal nanocatalysts supported on HfC(001 for O2 dissociation

    Directory of Open Access Journals (Sweden)

    Shiyan Wang

    2017-03-01

    Full Text Available The adsorption and dissociation of O2 on the M4 (M=Au, Pd, Pt clusters supported on HfC(001 (Hafnium Carbide are investigated using ab initio density functional theory calculations. The geometric and electronic structures are analyzed in detail. It is found that the dissociation barriers of O2 on Au4/HfC(001 (0.26 eV, Pd4/HfC(001 (0.49 eV and Pt4/HfC(001 (0.09 eV are much smaller than those on the clean surfaces of HfC(001 (1.60 eV, Au(111 (1.37 eV, Pd(111 (1.0 and 0.91 eV and Pt(111 (0.27–0.7 eV, respectively. The low dissociation barriers imply that the Pt4/HfC(001 exhibits the highest catalytic activity for O2 dissociation, and the Au4/HfC(001 and Pd4/HfC(001 may also be possible substitutes with lower cost for the current Pt/C catalyst for O2 dissociation. The present study is conductive to designing new efficient noble metal catalyst using HfC support for efficiently promoting O2 dissociation.

  15. Efficient noble metal nanocatalysts supported on HfC(001) for O2 dissociation

    Science.gov (United States)

    Wang, Shiyan; Zhang, Xilin; Zhang, Yanxing; Mao, Jianjun; Yang, Zongxian

    2017-03-01

    The adsorption and dissociation of O2 on the M4 (M=Au, Pd, Pt) clusters supported on HfC(001) (Hafnium Carbide) are investigated using ab initio density functional theory calculations. The geometric and electronic structures are analyzed in detail. It is found that the dissociation barriers of O2 on Au4/HfC(001) (0.26 eV), Pd4/HfC(001) (0.49 eV) and Pt4/HfC(001) (0.09 eV) are much smaller than those on the clean surfaces of HfC(001) (1.60 eV), Au(111) (1.37 eV), Pd(111) (1.0 and 0.91 eV) and Pt(111) (0.27-0.7 eV), respectively. The low dissociation barriers imply that the Pt4/HfC(001) exhibits the highest catalytic activity for O2 dissociation, and the Au4/HfC(001) and Pd4/HfC(001) may also be possible substitutes with lower cost for the current Pt/C catalyst for O2 dissociation. The present study is conductive to designing new efficient noble metal catalyst using HfC support for efficiently promoting O2 dissociation.

  16. Study of Direct-Contact HfO2/Si Interfaces

    Directory of Open Access Journals (Sweden)

    Noriyuki Miyata

    2012-03-01

    Full Text Available Controlling monolayer Si oxide at the HfO2/Si interface is a challenging issue in scaling the equivalent oxide thickness of HfO2/Si gate stack structures. A concept that the author proposes to control the Si oxide interface by using ultra-high vacuum electron-beam HfO2 deposition is described in this review paper, which enables the so-called direct-contact HfO2/Si structures to be prepared. The electrical characteristics of the HfO2/Si metal-oxide-semiconductor capacitors are reviewed, which suggest a sufficiently low interface state density for the operation of metal-oxide-semiconductor field-effect-transistors (MOSFETs but reveal the formation of an unexpected strong interface dipole. Kelvin probe measurements of the HfO2/Si structures provide obvious evidence for the formation of dipoles at the HfO2/Si interfaces. The author proposes that one-monolayer Si-O bonds at the HfO2/Si interface naturally lead to a large potential difference, mainly due to the large dielectric constant of the HfO2. Dipole scattering is demonstrated to not be a major concern in the channel mobility of MOSFETs.

  17. Structural degradation of thin HfO2 film on Ge during the postdeposition annealing

    Science.gov (United States)

    Miyata, Noriyuki; Yasuda, Tetsuji; Abe, Yasuhiro

    2010-05-01

    Securing the thermal robustness of thin hafnium oxide (HfO2) film on the semiconductor surface is an important technical issue in the fabrication of the metal-oxide-semiconductor field-effect transistor devices, as the HfO2-based high-k gate stacks usually undergo high-temperature processes. In this study, the structural development of thin HfO2 film on a Ge surface during postdeposition annealing in an ultrahigh vacuum was examined to explore the origin for the initial degradation of thin HfO2 film. Void nucleation and subsequent two-dimensional void growth take place at 780-840 °C, while the chemical composition of the remaining Hf oxide is virtually stable. Both the void nucleation and growth processes show similar larger activation energy of about 10 eV. Based on the observed manner of void growth and the estimated activation energies, the authors propose that mass transport on the HfO2 surface is responsible for void nucleation in the HfO2 films on Ge. The authors also compare the present results with the previous studies on HfO2/Si structures, and suggest that similar surface process leads to the local Hf silicidation.

  18. The effect of Cu doping concentration on resistive switching of HfO{sub 2} film

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Tingting; Tan, Tingting, E-mail: tantt@nwpu.edu.cn; Liu, Zhengtang

    2015-10-01

    Graphical abstract: - Highlights: • The Cu doped and undoped HfO{sub 2} films were fabricated. • The improved RS behaviors were observed for Cu doped HfO{sub 2} film with BRS. • The 9.7% doped HfO{sub 2}:Cu film showed both BRS and URS behaviors. • The related switching mechanisms were illustrated. - Abstract: The Cu-doped and undoped HfO{sub 2} films were fabricated and the effect of Cu doping concentration on resistive switching (RS) of HfO{sub 2} film was demonstrated. The X-ray photoelectron spectroscopy (XPS) was carried out to investigate the chemical bonding states of Cu in HfO{sub 2}:Cu film. The improved RS behaviors in terms of ON/OFF ratio and switching parameters were observed for Cu-doped HfO{sub 2} film with bipolar resistive switching (BRS) behavior. With the increase of Cu doping concentration, the 9.7% Cu-doped HfO{sub 2} film showed both BRS and unipolar resistive switching (URS) behaviors with large operating voltages. The space charge limited current (SCLC) effect was proposed to interpret the switching mechanism of HfO{sub 2}:Cu films with BRS behavior and the URS behavior can be explained by the migration of Cu ions.

  19. Lu-hf total-rock isochron for the eucrite meteorites

    Science.gov (United States)

    Patchett, P.J.; Tatsumoto, M.

    1980-01-01

    The isotope 176Lu (2.6% of natural lutetium) decays by ??- to 176Hf, with a long half life. We present here the first Lu-Hf isochron. The eucrite meteorites, a suite of planetary igneous rocks of known age, 4,550 Myr, define a 10-point total-rock isochron with a slope of 0.0934 ?? 40, leading to a value of 3.53 ?? 0.14 ??1010yr for the ??--decay half life of 176Lu. The isochron intercept of 0.27973 ?? 12 gives the initial 176Hf/177Hf for the inner Solar System at the time of accretion. ?? 1980 Nature Publishing Group.

  20. Chemical stability and defect formation in CaHfO3

    KAUST Repository

    Alay-E-Abbas, Syed Muhammad

    2014-04-01

    Defects in CaHfO3 are investigated by ab initio calculations based on density functional theory. Pristine and anion-deficient CaHfO 3 are found to be insulating, whereas cation-deficient CaHfO 3 is hole-doped. The formation energies of neutral and charged cation and anion vacancies are evaluated to determine the stability in different chemical environments. Moreover, the energies of the partial and full Schottky defect reactions are computed. We show that clustering of anion vacancies in the HfO layers is energetically favorable for sufficiently high defect concentrations and results in metallicity. © 2014 EPLA.

  1. Anticooperativity of FHF hydrogen bonds in clusters of the type F- × (HF)n, RF × (HF)n and XF × (HF)n, R = alkyl and X = H, Br, Cl, F

    Science.gov (United States)

    Kucherov, S. Yu.; Bureiko, S. F.; Denisov, G. S.

    2016-02-01

    Properties of twenty five hydrogen-bonded complexes, namely, F- × (HF)n (n = 1-6), RF × (HF)n (R = t-Bu, i-Pr, Et, Me; n = 1-3), XF × (HF)n (X = H, Br, Cl; n = 1-2), and FF…HF with the hydrogen bond energy varying in a wide range have been calculated using ab initio methods at the MP2/6-31++G** level. For the first time, the energies, geometrical parameters and vibrational frequencies are obtained for the series of clusters, where the bonding character changes from covalent to van der Waals on the variation of proton-acceptor ability of the base, and the energies are in the range of 45-1 kcal/mol. The mutual influence of multiple hydrogen bonds of F…HF type in clusters, in which a fluorine anion or an atom participates in hydrogen bond formation as the acceptor, is systematically investigated. The relative changes in the values of the considered parameters on the sequential addition of an HF molecule (anticooperativity) were determined. It was shown that non-additivity of the interaction is most strongly pronounced in the energy and vibrational frequency values, geometrical parameters of hydrogen bonds are less sensitive to the mutual influence. The anticooperative effect is more pronounced on the hydrogen bridge length R(F...F) than on the geometry of proton donor r(HF). The hydrogen bond formation and the increase of the number n of ligands lead to successive lengthening of the r(XF) bond adjacent to the hydrogen bridge. The length of an XF bond changes stronger on formation of each hydrogen bond than the HF bond length.

  2. Simulations of resonant Alfvén waves generated by artificial HF heating of the auroral ionosphere

    Directory of Open Access Journals (Sweden)

    D. Pokhotelov

    2004-09-01

    Full Text Available Numerical two-dimensional two-fluid MHD simulations of dynamic magnetosphere-ionosphere (MI coupling have been performed to model the effects imposed on the auroral ionosphere by a powerful HF radio wave transmitter. The simulations demonstrate that modifications of the ionospheric plasma temperature and recombination due to artificial heating may trigger the ionospheric feedback instability when the coupled MI system is close to the state of marginal stability. The linear dispersion analysis of MI coupling has been performed to find the favorable conditions for marginal stability of the system. The development of the ionospheric feedback instability leads to the generation of shear waves which resonate in the magnetosphere between the heated ionospheric E-region and the strong gradient in the speed at altitudes of 1-2 RE. The application of the numerical results for the explanation of observations performed by low-orbiting satellites above the high-latitude ionosphere heated with a high power ground-based HF transmitter is discussed.

  3. [Percentage of psychoemotional problems in Spanish children and adolescents. Differences between 2006 and 2012].

    Science.gov (United States)

    Basterra, Virginia

    2016-11-04

    To examine the percentage of psychoemotional problems in Spanish children and adolescents and the difference between 2006 and 2012. Data from 9,761 participants were taken from the Spanish National Health Survey of 2006 and 2012. The Goodman Strengths and Difficulties Questionnaire was used to assess mental health. The percentage of participants with abnormal scores in the different scales was calculated. Chi-square test and multivariate logistic regression models adjusted for age, sex, social level and adult mental health status were used. In 2012, the percentage of Spanish youths with emotional, conduct, hyperactivity, peer and prosocial problems and abnormal total problem score was 8.5, 6.7, 10.2, 7.7, 0.7 and 4%, respectively. In 2006, these percentages were 11.5, 10.2, 14.7, 10.1, 0.9 and 6.7%. A significant reduction was found for the percentage of children and adolescents with problematic behavior between 2006 and 2012. Based on the total problem score, about 4% of Spanish youths suffer from psychoemotional problems. This percentage has decreased between 2006 and 2012. Copyright © 2016 Elsevier España, S.L.U. All rights reserved.

  4. Power spectral analysis of heart rate variability for assessment of diurnal variation of autonomic nervous activity in guinea pigs.

    Science.gov (United States)

    Akita, Megumi; Ishii, Keiji; Kuwahara, Masayoshi; Tsubone, Hirokazu

    2002-01-01

    We established characteristics of power spectral analysis of heart rate variability, and assessed the diurnal variations of autonomic nervous function in guinea pigs. For this purpose, an electrocardiogram (ECG) was recorded for 24 hr from conscious and unrestrained guinea pigs using a telemetry system. There were two major spectral components, at low frequency (LF) and high frequency (HF) bands, in the power spectrum of HR variability. On the basis of these data, we defined two frequency bands of interest: LF (0.07-0.7 Hz) and HF (0.7-3.0 Hz). The power of LF was higher than that of HF in the normal guinea pigs. Atropine significantly reduced power at HF. Propranolol also significantly reduced power at LF. Furthermore, the decrease in the parasympathetic mechanism produced by atropine was reflected in a slight increase in the LF/HF ratio. The LF/HF ratio appeared to follow the reductions of sympathetic activity produced by propranolol. Autonomic blockade studies indicated that the HF component reflected parasympathetic activity and the LF/HF ratio seemed to be a convenient index of autonomic balance. Nocturnal patterns, in which the values of heart rate in the dark phase (20:00-06:00) were higher than those in the light phase (06:00-20:00), were observed. However, the HF, LF and the LF/HF ratio showed no daily pattern. These results suggest that the autonomic nervous function in guinea pigs has no clear circadian rhythmicity. Therefore, this information may be useful for future studies concerning the autonomic nervous function in this species.

  5. Effects of Hf Incorporation on Negative Bias-Illumination Stress Stability in Hf-In-Zn-O Thin-Film Transistors

    Science.gov (United States)

    Kim, Sangwook; Park, Jae Chul; Kim, Dae Hwan; Lee, Jang-Sik

    2013-04-01

    In this study, highly reliable amorphous oxide semiconductor-based thin-film transistors (TFTs) were developed. The Hf concentration was systematically changed in the Hf-incorporated In-Zn-O (HIZO) TFTs, and Hf played an important role in determining the negative bias-illumination instability. The process parameters were optimized in order to obtain HIZO TFTs with an excellent stability. HIZO can be processed on a 6-in. wafer at low temperatures and is almost transparent in the visible range. Thus this material is promising for use in current TFTs as well as future transparent electronic device components with good electrical performance and excellent stability.

  6. Phase1 upgrade of the CMS-HF Calorimeter

    CERN Document Server

    Gulmez, Erhan

    2016-01-01

    In this presentation, results of the Phase I upgrade of the CMS Hadron Forward Calorimeter (HF) are discussed. The CMS-HF Calorimeter was using regular PMTs. Cherenkov light produced in the quartz fibers embedded in the iron absorber was read out with the PMTs. However, occasionally, stray muons hitting the PMT windows cause Cherenkov radiation in the PMT itself and produce large signals. These large signals mimic a very high-energy particle and are tagged as important by the trigger. To reduce this problem, PMTs had to be replaced. The four-anode PMTs that were chosen have thinner windows; thereby reducing the Cherenkov radiation in the PMT window. As part of the upgrade, the read-out electronics is to be replaced so that the PMTs are read out in two channels by connecting each pair of anodes to a single channel. Information provided by these two channels will help us reject the false signals due to the stray muons since the Cherenkov radiation in the PMT window is more likely to produce a signal only in one...

  7. Reversible spin texture in ferroelectric Hf O2

    Science.gov (United States)

    Tao, L. L.; Paudel, Tula R.; Kovalev, Alexey A.; Tsymbal, Evgeny Y.

    2017-06-01

    Spin-orbit coupling effects occurring in noncentrosymmetric materials are known to be responsible for nontrivial spin configurations and a number of emergent physical phenomena. Ferroelectric materials may be especially interesting in this regard due to reversible spontaneous polarization making possible a nonvolatile electrical control of the spin degrees of freedom. Here, we explore a technologically relevant oxide material, Hf O2 , which has been shown to exhibit robust ferroelectricity in a noncentrosymmetric orthorhombic phase. Using theoretical modelling based on density-functional theory, we investigate the spin-dependent electronic structure of the ferroelectric Hf O2 and demonstrate the appearance of chiral spin textures driven by spin-orbit coupling. We analyze these spin configurations in terms of the Rashba and Dresselhaus effects within the k .p Hamiltonian model and find that the Rashba-type spin texture dominates around the valence-band maximum, while the Dresselhaus-type spin texture prevails around the conduction band minimum. The latter is characterized by a very large Dresselhaus constant λD= 0.578 eV Å, which allows using this material as a tunnel barrier to produce tunneling anomalous and spin Hall effects that are reversible by ferroelectric polarization.

  8. Radiation effects in Zr and Hf containing garnets

    Energy Technology Data Exchange (ETDEWEB)

    Whittle, Karl R. [Institute of Materials Engineering, Australian Nuclear Science and Technology Organisation, PMB1, Menai, NSW 2234 (Australia); Department of Materials Science and Engineering, University of Sheffield, Mappin Street, Sheffield S1 3JD (United Kingdom); Blackford, Mark G.; Smith, Katherine L. [Institute of Materials Engineering, Australian Nuclear Science and Technology Organisation, PMB1, Menai, NSW 2234 (Australia); Zaluzec, Nestor J. [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Weyland, Matthew [Monash Centre for Electron Microscopy, Monash University, Victoria 3800 (Australia); Department of Materials Engineering, Monash University, Victoria 3800 (Australia); Lumpkin, Gregory R. [Institute of Materials Engineering, Australian Nuclear Science and Technology Organisation, PMB1, Menai, NSW 2234 (Australia)

    2015-07-15

    Garnets have been considered as host phases for the safe immobilisation of high-level nuclear waste, as they have been shown to accommodate a wide range of elements across three different cation sites, such as Ca, Y, Mn on the a-site, Fe, Al, U, Zr, and Ti on the b-site, and Si, Fe, Al on the c-site. Garnets, due to their ability to have variable composition, make ideal model materials for the examination of radiation damage and recovery in nuclear materials, including as potential waste forms. Kimzeyite, Ca{sub 3}Zr{sub 2}FeAlSiO{sub 12}, has been shown naturally to contain up to 30 wt% Zr, and has previously been examined to elucidate both the structure and ordering within the lattice. This study examines the effects of radiation damage and recovery using in-situ ion beam irradiation with 1 MeV Kr ions at the IVEM-TANDEM facility, Argonne National Laboratory. The complementary Hf containing system Ca{sub 3}Hf{sub 2}FeAlSiO{sub 12} was also examined, and found to have a different response to irradiation damage. A sample of irradiated Ca{sub 3}Zr{sub 2}FeAlSiO{sub 12}, at 1000 K, was characterised using aberration corrected (S)TEM and found to contain discreet, nano-sized, crystalline Fe rich particles, indicating a competing process during recovery is occurring.

  9. Interrogation zone determination in HF RFID systems with multiplexed antennas*

    Directory of Open Access Journals (Sweden)

    Jankowski-Mihułowicz Piotr

    2015-09-01

    Full Text Available The operation of an anti-collision RFID system is characterized by the interrogation zone which should be estimated in any direction of 3D space for a group of electronic transponders. The interrogation zone should be as large as possible. However, the many problems in this area are due to the fact that energy can be transferred to transponders only on a limited distance. The greatest flexibility in developing RFID applications and shaping the interrogation zone can be achieved using the system with an antenna multiplexer. Therefore the problem of the interrogation zone determination in HF RFID systems with two orthogonal RWD antennas is presented in the paper. The perceived issues have been effectively dealt with and the solution has been proposed on the basis of the elaborated model. Conducted studies have been used to develop the software tool JankoRFIDmuxHF in the Mathcad environment. The research results are analysed in an example system configuration. The specialized measuring stand has been used for experimental verification of the identification efficiency. The convergence of the measurements and calculations confirms a practical usefulness of the presented concept of interrogation zone determination in anti-collision systems. It also shows the practical utility of the developed model and software tools.

  10. The role of Upper Hybrid Turbulence on HF Artificial Ionization

    Science.gov (United States)

    Papadopoulos, Konstantinos Dennis; Najmi, Amir; Eliasson, Bengt; Milikh, Gennady

    2016-07-01

    One of the most fascinating and scientifically interesting phenomena of active space experiments is the discovery of artificial ionization by Todd Pedersen when the HAARP ERP reached the GW level. The phenomenon has been well documented experimentally. A theoretical model based on ionization by energetic electrons accelerated by 50-100 V/m localized electric fields due to Strong Langmuir Turbulence (SLT) near the reflection surface of the HF pump wave, reproduced the observed dynamics of the descending plasma layer quite accurately. A major defect of the model was that the electron temperature in the SLT region was a free parameter. When taken as the 2000 K representing the ambient electron temperature the SLT driven electron flux was insufficient to produce ionization. An equivalent electron temperature of 5000 K or higher was necessary to reproduce the observations. The needed electron heating was attributed to the interaction of the HF at the Upper Hybrid (UH) resonant layer, approximately 5 Km below the reflection region where the HF electric field is perpendicular to the ambient magnetic field. The heated electrons expanded upwards along the magnetic field line and interacted with SLT fields near the resonance region. A consequence of this defect was that the theory could not explain the puzzling double resonance effect. Namely the observation that the ionization level was much stronger when the HF frequency and the UH resonance were a multiple of the electron cyclotron frequency. To remedy this we used a series of Vlasov simulations to explore the HF-plasma interaction in the vicinity of the UH resonance. The simulations followed the evolution of the spectral density of the electric field over a 7.5 MHz frequency band and cm scale lengths and of the electron distribution function over one millisecond for both double resonant and non-resonant cases. Many new features were revealed by the analysis of the simulations such as: 1. Broadening of the wave

  11. Electron Microprobe Analysis of Hf in Zircon: Suggestions for Improved Accuracy of a Difficult Measurement

    Science.gov (United States)

    Fournelle, J.; Hanchar, J. M.

    2013-12-01

    It is not commonly recognized as such, but the accurate measurement of Hf in zircon is not a trivial analytical issue. This is important to assess because Hf is often used as an internal standard for trace element analyses of zircon by LA-ICPMS. The issues pertaining to accuracy revolve around: (1) whether the Hf Ma or the La line is used; (2) what accelerating voltage is applied if Zr La is also measured, and (3) what standard for Hf is used. Weidenbach, et al.'s (2004) study of the 91500 zircon demonstrated the spread (in accuracy) of possible EPMA values for six EPMA labs, 2 of which used Hf Ma, 3 used Hf La, and one used Hf Lb, and standards ranged from HfO2, a ZrO2-HfO2 compound, Hf metal, and hafnon. Weidenbach, et al., used the ID-TIMS values as the correct value (0.695 wt.% Hf.), for which not one of the EPMA labs came close to that value (3 were low and 3 were high). Those data suggest: (1) that there is a systematic underestimation error of the 0.695 wt% Hf (ID-TIMS Hf) value if Hf Ma is used; most likely an issue with the matrix correction, as the analytical lines and absorption edges of Zr La, Si Ka and Hf Ma are rather tightly packed in the electromagnetic spectrum. Mass absorption coefficients are easily in error (e.g., Donovan's determination of the MAC of Hf by Si Ka of 5061 differs from the typically used Henke value of 5449 (Donovan et al, 2002); and (2) For utilization of the Hf La line, however, the second order Zr Ka line interferes with Hf La if the accelerating voltage is greater than 17.99 keV. If this higher keV is used and differential mode PHA is applied, only a portion of the interference is removed (e.g., removal of escape peaks), causing an overestimation of Hf content. Unfortunately, it is virtually impossible to apply an interference correction in this case, as it is impossible to locate Hf-free Zr probe standard. We have examined many of the combinations used by those six EPMA labs and concluded that the optimal EPMA is done with Hf

  12. Percentage of Positive Biopsy Cores: A Better Risk Stratification Model for Prostate Cancer?

    Energy Technology Data Exchange (ETDEWEB)

    Huang Jiayi; Vicini, Frank A. [Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, MI (United States); Williams, Scott G. [Peter Maccallum Cancer Centre and University of Melbourne, Melbourne, Victoria (Australia); Ye Hong; McGrath, Samuel; Ghilezan, Mihai; Krauss, Daniel; Martinez, Alvaro A. [Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, MI (United States); Kestin, Larry L., E-mail: lkestin@comcast.net [Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, MI (United States)

    2012-07-15

    Purpose: To assess the prognostic value of the percentage of positive biopsy cores (PPC) and perineural invasion in predicting the clinical outcomes after radiotherapy (RT) for prostate cancer and to explore the possibilities to improve on existing risk-stratification models. Methods and Materials: Between 1993 and 2004, 1,056 patients with clinical Stage T1c-T3N0M0 prostate cancer, who had four or more biopsy cores sampled and complete biopsy core data available, were treated with external beam RT, with or without a high-dose-rate brachytherapy boost at William Beaumont Hospital. The median follow-up was 7.6 years. Multivariate Cox regression analysis was performed with PPC, Gleason score, pretreatment prostate-specific antigen, T stage, PNI, radiation dose, androgen deprivation, age, prostate-specific antigen frequency, and follow-up duration. A new risk stratification (PPC classification) was empirically devised to incorporate PPC and replace the T stage. Results: On multivariate Cox regression analysis, the PPC was an independent predictor of distant metastasis, cause-specific survival, and overall survival (all p < .05). A PPC >50% was associated with significantly greater distant metastasis (hazard ratio, 4.01; 95% confidence interval, 1.86-8.61), and its independent predictive value remained significant with or without androgen deprivation therapy (all p < .05). In contrast, PNI and T stage were only predictive for locoregional recurrence. Combining the PPC ({<=}50% vs. >50%) with National Comprehensive Cancer Network risk stratification demonstrated added prognostic value of distant metastasis for the intermediate-risk (hazard ratio, 5.44; 95% confidence interval, 1.78-16.6) and high-risk (hazard ratio, 4.39; 95% confidence interval, 1.70-11.3) groups, regardless of the use of androgen deprivation and high-dose RT (all p < .05). The proposed PPC classification appears to provide improved stratification of the clinical outcomes relative to the National

  13. Quantitative trait loci mapping and genetic dissection for lint percentage in upland cotton (Gossypium hirsutum)

    Indian Academy of Sciences (India)

    Min Wang; Chengqi Li; Qinglian Wang

    2014-08-01

    Lint percentage is an important character of cotton yield components and it is also correlated with cotton fibre development. In this study, we used a high lint percentage variety, Baimian1, and a low lint percentage, TM-1 genetic standard for Gossypium hirsutum, as parents to construct a mapping populations in upland cotton (G. hirsutum). A quantitative trait locus/loci (QTL) analysis of lint percentage was performed by using two mapping procedures; composite interval mapping (CIM), inclusive composite interval mapping (ICIM) and the F2:3 populations in 2 years. Six main-effect QTL (M-QTL) for lint percentage (four significant and two suggestive) were detected in both years by CIM, and were located on chr. 3, chr. 19, chr. 26 and chr. 5 /chr. 19. Of the six QTL, marker intervals and favourable gene sources of the significant M-QTL, qLP-3(2010) and qLP-3(2011) were consistent. These QTL were also detected by ICIM, and therefore, should preferentially be used for marker-assisted selection (MAS) of lint percentage. Another M-QTL, qLP-19(2010), was detected by two mapping procedures, and it could also be a candidate for MAS. We detected the interaction between two M-QTL and environment, and 11 epistatic QTL (E-QTL) and their interaction with environment by using ICIM. The study also found two EST-SSRs, NAU1187 and NAU1255, linked to M-QTL for lint percentage that could be candidate markers affecting cotton fibre development.

  14. Use of claims data to estimate annual cervical cancer screening percentages in Portland metropolitan area, Oregon.

    Science.gov (United States)

    Abdullah, Nasreen; Laing, Robert S; Hariri, Susan; Young, Collette M; Schafer, Sean

    2016-04-01

    Human papillomavirus (HPV) vaccine should reduce cervical dysplasia before cervical cancer. However, dysplasia diagnosis is screening-dependent. Accurate screening estimates are needed. To estimate the percentage of women in a geographic population that has had cervical cancer screening. We analyzed claims data for (Papanicolau) Pap tests from 2008-2012 to estimate the percentage of insured women aged 18-39 years screened. We estimated screening in uninsured women by dividing the percentage of insured Behavioral Risk Factor Surveillance Survey respondents reporting previous-year testing by the percentage of uninsured respondents reporting previous-year testing, and multiplying this ratio by claims-based estimates of insured women with previous-year screening. We calculated a simple weighted average of the two estimates to estimate overall screening percentage. We estimated credible intervals using Monte-Carlo simulations. During 2008-2012, an annual average of 29.6% of women aged 18-39 years were screened. Screening increased from 2008 to 2009 in all age groups. During 2009-2012, the screening percentages decreased for all groups, but declined most in women aged 18-20 years, from 21.5% to 5.4%. Within age groups, compared to 2009, credible intervals did not overlap during 2011 (except age group 21-29 years) and 2012, and credible intervals in the 18-20 year group did not overlap with older groups in any year. This introduces a novel method to estimate population-level cervical cancer screening. Overall, percentage of women screened in Portland, Oregon fell following changes in screening recommendations released in 2009 and later modified in 2012. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Change with age in regression construction of fat percentage for BMI in school-age children.

    Science.gov (United States)

    Fujii, Katsunori; Mishima, Takaaki; Watanabe, Eiji; Seki, Kazuyoshi

    2011-01-01

    In this study, curvilinear regression was applied to the relationship between BMI and body fat percentage, and an analysis was done to see whether there are characteristic changes in that curvilinear regression from elementary to middle school. Then, by simultaneously investigating the changes with age in BMI and body fat percentage, the essential differences in BMI and body fat percentage were demonstrated. The subjects were 789 boys and girls (469 boys, 320 girls) aged 7.5 to 14.5 years from all parts of Japan who participated in regular sports activities. Body weight, total body water (TBW), soft lean mass (SLM), body fat percentage, and fat mass were measured with a body composition analyzer (Tanita BC-521 Inner Scan), using segmental bioelectrical impedance analysis & multi-frequency bioelectrical impedance analysis. Height was measured with a digital height measurer. Body mass index (BMI) was calculated as body weight (km) divided by the square of height (m). The results for the validity of regression polynomials of body fat percentage against BMI showed that, for both boys and girls, first-order polynomials were valid in all school years. With regard to changes with age in BMI and body fat percentage, the results showed a temporary drop at 9 years in the aging distance curve in boys, followed by an increasing trend. Peaks were seen in the velocity curve at 9.7 and 11.9 years, but the MPV was presumed to be at 11.9 years. Among girls, a decreasing trend was seen in the aging distance curve, which was opposite to the changes in the aging distance curve for body fat percentage.

  16. Quantitative trait loci mapping and genetic dissection for lint percentage in upland cotton (Gossypium hirsutum).

    Science.gov (United States)

    Wang, Min; Li, Chengqi; Wang, Qinglian

    2014-08-01

    Lint percentage is an important character of cotton yield components and it is also correlated with cotton fibre development. In this study, we used a high lint percentage variety, Baimian1, and a low lint percentage, TM-1 genetic standard for Gossypium hirsutum, as parents to construct a mapping populations in upland cotton (G. hirsutum). A quantitative trait locus/loci (QTL) analysis of lint percentage was performed by using two mapping procedures; composite interval mapping (CIM), inclusive composite interval mapping (ICIM) and the F2:3 populations in 2 years. Six main-effect QTL (M-QTL) for lint percentage (four significant and two suggestive) were detected in both years by CIM, and were located on chr. 3, chr. 19, chr. 26 and chr. 5/chr. 19. Of the six QTL, marker intervals and favourable gene sources of the significant M-QTL, qLP-3(2010) and qLP-3(2011) were consistent. These QTL were also detected by ICIM, and therefore, should preferentially be used for markerassisted selection (MAS) of lint percentage. Another M-QTL, qLP-19(2010), was detected by two mapping procedures, and it could also be a candidate for MAS. We detected the interaction between two M-QTL and environment, and 11 epistatic QTL (E-QTL) and their interaction with environment by using ICIM. The study also found two EST-SSRs, NAU1187 and NAU1255, linked to M-QTL for lint percentage that could be candidate markers affecting cotton fibre development.

  17. Evolution of continental crust and mantle heterogeneity: Evidence from Hf isotopes

    Science.gov (United States)

    Jonathan, Patchett P.; Kouvo, O.; Hedge, C.E.; Tatsumoto, M.

    1982-01-01

    We present initial 176Hf/177 Hf ratios for many samples of continental crust 3.7-0.3 Gy old. Results are based chiefly on zircons (1% Hf) and whole rocks: zircons are shown to be reliable carriers of essentially the initial Hf itself when properly chosen on the basis of U-Pb studies. Pre-3.0 Gy gneisses were apparently derived from an unfractionated mantle, but both depleted and undepleted mantle are evident as magma sources from 2.9 Gy to present. This mantle was sampled mainly from major crustal growth episodes 2.8, 1.8 and 0.7 Gy ago, all of which show gross heterogeneity of 176Hf/177Hf in magma sources from ??Hf=0 to +14, or about 60% of the variability of the present mantle. The approximate ??Hf=2??Nd relationship in ancient and modern igneous rocks shows that 176Lu/177Hf fractionates in general twice as much as 147Sm/144Nd in mantle melting processes. This allows an estimation of the relative value of the unknown bulk solid/liquid distribution coefficient for Hf. DLu/DHf=??? 2.3 holds for most mantle source regions. For garnet to be an important residual mantle phase, it must hold Hf strongly in order to preserve Hf-Nd isotopic relationships. The ancient Hf initials are consistent with only a small proportion of recycled older cratons in new continental crust, and with quasi-continuous, episodic growth of the continental crust with time. However, recycling of crust less than 150 My old cannot realistically be detected using Hf initials. The mantle shows clearly the general positive ??Hf resulting from a residual geochemical state at least back to 2.9 Gy ago, and seems to have repeatedly possessed a similar degree of heterogeneity, rather than a continuously-developing depletion. This is consistent with a complex dynamic disequilibrium model for the creation, maintenance and destruction of heterogeneity in the mantle. ?? 1981 Springer-Verlag.

  18. What Hf isotopes in zircon tell us about crust-mantle evolution

    Science.gov (United States)

    Iizuka, Tsuyoshi; Yamaguchi, Takao; Itano, Keita; Hibiya, Yuki; Suzuki, Kazue

    2017-03-01

    The 176Lu-176Hf radioactive decay system has been widely used to study planetary crust-mantle differentiation. Of considerable utility in this regard is zircon, a resistant mineral that can be precisely dated by the U-Pb chronometer and record its initial Hf isotope composition due to having low Lu/Hf. Here we review zircon U-Pb age and Hf isotopic data mainly obtained over the last two decades and discuss their contributions to our current understanding of crust-mantle evolution, with emphasis on the Lu-Hf isotope composition of the bulk silicate Earth (BSE), early differentiation of the silicate Earth, and the evolution of the continental crust over geologic history. Meteorite zircon encapsulates the most primitive Hf isotope composition of our solar system, which was used to identify chondritic meteorites best representative of the BSE (176Hf/177Hf = 0.282793 ± 0.000011; 176Lu/177Hf = 0.0338 ± 0.0001). Hadean-Eoarchean detrital zircons yield highly unradiogenic Hf isotope compositions relative to the BSE, providing evidence for the development of a geochemically enriched silicate reservoir as early as 4.5 Ga. By combining the Hf and O isotope systematics, we propose that the early enriched silicate reservoir has resided at depth within the Earth rather than near the surface and may represent a fractionated residuum of a magma ocean underlying the proto-crust, like urKREEP beneath the anorthositic crust on the Moon. Detrital zircons from world major rivers potentially provide the most robust Hf isotope record of the preserved granitoid crust on a continental scale, whereas mafic rocks with various emplacement ages offer an opportunity to trace the Hf isotope evolution of juvenile continental crust (from εHf[4.5 Ga] = 0 to εHf[present] = + 13). The river zircon data as compared to the juvenile crust composition highlight that the supercontinent cycle has controlled the evolution of the continental crust by regulating the rates of crustal generation and intra

  19. Influence of Hf contents on interface state properties in a-HfInZnO thin-film transistors with SiNx/SiOx gate dielectrics

    Science.gov (United States)

    Choi, Hyun-Sik; Jeon, Sanghun; Kim, Hojung; Shin, Jaikwang; Kim, Changjung; Chung, U.-In

    2011-10-01

    We evaluated the interface properties of amorphous hafnium-indium-zinc-oxide (a-HIZO) thin-film transistors (TFTs) with respect to various Hf contents. To this end, the subthreshold swing and the low-frequency noise (LFN) of the a-HIZO TFTs were measured and compared. From LFNs providing more accurate information, we quantitatively analyzed the interface trap densities and found that they decrease with increasing Hf contents. Although the acceptor-like tail state densities in bulk channel increase with Hf contents, higher Hf contents show lower threshold voltage shift under bias stress, implying that reliability characteristics of a-HIZO TFTs are more sensitive to interface quality rather than bulk property.

  20. Distribution of p-process 174Hf in early solar system materials and the origin of nucleosynthetic Hf and W isotope anomalies in Ca-Al rich inclusions

    Science.gov (United States)

    Peters, Stefan T. M.; Münker, Carsten; Pfeifer, Markus; Elfers, Bo-Magnus; Sprung, Peter

    2017-02-01

    Some nuclides that were produced in supernovae are heterogeneously distributed between different meteoritic materials. In some cases these heterogeneities have been interpreted as the result of interaction between ejecta from a nearby supernova and the nascent solar system. Particularly in the case of the oldest objects that formed in the solar system - Ca-Al rich inclusions (CAIs) - this view is confirm the hypothesis that a nearby supernova event facilitated or even triggered solar system formation. We present Hf isotope data for bulk meteorites, terrestrial materials and CAIs, for the first time including the low-abundance isotope 174Hf (∼0.16%). This rare isotope was likely produced during explosive O/Ne shell burning in massive stars (i.e., the classical "p-process"), and therefore its abundance potentially provides a sensitive tracer for putative heterogeneities within the solar system that were introduced by supernova ejecta. For CAIs and one LL chondrite, also complementary W isotope data are reported for the same sample cuts. Once corrected for small neutron capture effects, different chondrite groups, eucrites, a silicate inclusion of a IAB iron meteorite, and terrestrial materials display homogeneous Hf isotope compositions including 174Hf. Hafnium-174 was thus uniformly distributed in the inner solar system when planetesimals formed at the system composition, and also variable r-process (or s-process) Hf and W contributions. Based on combined Hf and W isotope compositions, we show that CAIs sampled at least one component in which the proportion of r- and s-process derived Hf and W deviates from that of supernova ejecta. The Hf and W isotope anomalies in CAIs are therefore best explained by selective processing of presolar carrier phases prior to CAI formation, and not by a late injection of supernova materials. Likewise, other isotope anomalies in additional elements in CAIs relative to the bulk solar system may reflect the same process. The isotopic

  1. [THE PERCENTAGE OF BLOOD SERUM TESTS WITH HEMOLYSIS IN DIFFERENT GROUPS OF PATIENTS].

    Science.gov (United States)

    Moshkin, A V

    2015-06-01

    In the process of laboratory analysis most of the errors occur at the pre-analytical stage. The percentage of blood serum tests with hemolysis is largely applied as an indicator of quality of sampling and transport of blood tests in laboratory. The study was carried out to analyze percentage of tests with hemolysis in different groups of in- and out-patients. The percentage of tests with hemolysis was estimated according actual recommendation of IFCC working group "Laboratory Errors and Patient Safety" as percentage oftests with free hemoglobin more than 0.5 g/l of total amount of serum tests analyzed on biochemical analyzer capable to measure hemolysis index. The hemolysis was identified in 199 (1.4%) out of 14 170 samples. The large dispersion of results in different groups of patient was established. In children younger than 7 years treated in hospital percentage of hemolysis amounted to 2.44%, in patients of reanimation department - 2.38%. In adult patients of hospital this indicator of quality ranged from 0.31% to 1.59%. In two groups of out-patients this indicator amounted to 0.36% (clinic personnel, dispensarization) and 1.81% (out-patients). Such a dispersion complicates inter-laboratory comparison of quality according this particular indicator. The necessity is substantiated to apply more efforts concerning harmonization of indicators of quality in laboratory medicine.

  2. Air sensitivity of MoS2, MoSe2, MoTe2, HfS2, and HfSe2

    Science.gov (United States)

    Mirabelli, Gioele; McGeough, Conor; Schmidt, Michael; McCarthy, Eoin K.; Monaghan, Scott; Povey, Ian M.; McCarthy, Melissa; Gity, Farzan; Nagle, Roger; Hughes, Greg; Cafolla, Attilio; Hurley, Paul K.; Duffy, Ray

    2016-09-01

    A surface sensitivity study was performed on different transition-metal dichalcogenides (TMDs) under ambient conditions in order to understand which material is the most suitable for future device applications. Initially, Atomic Force Microscopy and Scanning Electron Microscopy studies were carried out over a period of 27 days on mechanically exfoliated flakes of 5 different TMDs, namely, MoS2, MoSe2, MoTe2, HfS2, and HfSe2. The most reactive were MoTe2 and HfSe2. HfSe2, in particular, showed surface protrusions after ambient exposure, reaching a height and width of approximately 60 nm after a single day. This study was later supplemented by Transmission Electron Microscopy (TEM) cross-sectional analysis, which showed hemispherical-shaped surface blisters that are amorphous in nature, approximately 180-240 nm tall and 420-540 nm wide, after 5 months of air exposure, as well as surface deformation in regions between these structures, related to surface oxidation. An X-ray photoelectron spectroscopy study of atmosphere exposed HfSe2 was conducted over various time scales, which indicated that the Hf undergoes a preferential reaction with oxygen as compared to the Se. Energy-Dispersive X-Ray Spectroscopy showed that the blisters are Se-rich; thus, it is theorised that HfO2 forms when the HfSe2 reacts in ambient, which in turn causes the Se atoms to be aggregated at the surface in the form of blisters. Overall, it is evident that air contact drastically affects the structural properties of TMD materials. This issue poses one of the biggest challenges for future TMD-based devices and technologies.

  3. Material insights of HfO2-based integrated 1-transistor-1-resistor resistive random access memory devices processed by batch atomic layer deposition

    Science.gov (United States)

    Niu, Gang; Kim, Hee-Dong; Roelofs, Robin; Perez, Eduardo; Schubert, Markus Andreas; Zaumseil, Peter; Costina, Ioan; Wenger, Christian

    2016-06-01

    With the continuous scaling of resistive random access memory (RRAM) devices, in-depth understanding of the physical mechanism and the material issues, particularly by directly studying integrated cells, become more and more important to further improve the device performances. In this work, HfO2-based integrated 1-transistor-1-resistor (1T1R) RRAM devices were processed in a standard 0.25 μm complementary-metal-oxide-semiconductor (CMOS) process line, using a batch atomic layer deposition (ALD) tool, which is particularly designed for mass production. We demonstrate a systematic study on TiN/Ti/HfO2/TiN/Si RRAM devices to correlate key material factors (nano-crystallites and carbon impurities) with the filament type resistive switching (RS) behaviours. The augmentation of the nano-crystallites density in the film increases the forming voltage of devices and its variation. Carbon residues in HfO2 films turn out to be an even more significant factor strongly impacting the RS behaviour. A relatively higher deposition temperature of 300 °C dramatically reduces the residual carbon concentration, thus leading to enhanced RS performances of devices, including lower power consumption, better endurance and higher reliability. Such thorough understanding on physical mechanism of RS and the correlation between material and device performances will facilitate the realization of high density and reliable embedded RRAM devices with low power consumption.

  4. Material insights of HfO2-based integrated 1-transistor-1-resistor resistive random access memory devices processed by batch atomic layer deposition.

    Science.gov (United States)

    Niu, Gang; Kim, Hee-Dong; Roelofs, Robin; Perez, Eduardo; Schubert, Markus Andreas; Zaumseil, Peter; Costina, Ioan; Wenger, Christian

    2016-06-17

    With the continuous scaling of resistive random access memory (RRAM) devices, in-depth understanding of the physical mechanism and the material issues, particularly by directly studying integrated cells, become more and more important to further improve the device performances. In this work, HfO2-based integrated 1-transistor-1-resistor (1T1R) RRAM devices were processed in a standard 0.25 μm complementary-metal-oxide-semiconductor (CMOS) process line, using a batch atomic layer deposition (ALD) tool, which is particularly designed for mass production. We demonstrate a systematic study on TiN/Ti/HfO2/TiN/Si RRAM devices to correlate key material factors (nano-crystallites and carbon impurities) with the filament type resistive switching (RS) behaviours. The augmentation of the nano-crystallites density in the film increases the forming voltage of devices and its variation. Carbon residues in HfO2 films turn out to be an even more significant factor strongly impacting the RS behaviour. A relatively higher deposition temperature of 300 °C dramatically reduces the residual carbon concentration, thus leading to enhanced RS performances of devices, including lower power consumption, better endurance and higher reliability. Such thorough understanding on physical mechanism of RS and the correlation between material and device performances will facilitate the realization of high density and reliable embedded RRAM devices with low power consumption.

  5. Material insights of HfO2-based integrated 1-transistor-1-resistor resistive random access memory devices processed by batch atomic layer deposition

    Science.gov (United States)

    Niu, Gang; Kim, Hee-Dong; Roelofs, Robin; Perez, Eduardo; Schubert, Markus Andreas; Zaumseil, Peter; Costina, Ioan; Wenger, Christian

    2016-01-01

    With the continuous scaling of resistive random access memory (RRAM) devices, in-depth understanding of the physical mechanism and the material issues, particularly by directly studying integrated cells, become more and more important to further improve the device performances. In this work, HfO2-based integrated 1-transistor-1-resistor (1T1R) RRAM devices were processed in a standard 0.25 μm complementary-metal-oxide-semiconductor (CMOS) process line, using a batch atomic layer deposition (ALD) tool, which is particularly designed for mass production. We demonstrate a systematic study on TiN/Ti/HfO2/TiN/Si RRAM devices to correlate key material factors (nano-crystallites and carbon impurities) with the filament type resistive switching (RS) behaviours. The augmentation of the nano-crystallites density in the film increases the forming voltage of devices and its variation. Carbon residues in HfO2 films turn out to be an even more significant factor strongly impacting the RS behaviour. A relatively higher deposition temperature of 300 °C dramatically reduces the residual carbon concentration, thus leading to enhanced RS performances of devices, including lower power consumption, better endurance and higher reliability. Such thorough understanding on physical mechanism of RS and the correlation between material and device performances will facilitate the realization of high density and reliable embedded RRAM devices with low power consumption. PMID:27312225

  6. EURObservational Research Programme : The Heart Failure Pilot Survey (ESC-HF Pilot)

    NARCIS (Netherlands)

    Maggioni, Aldo P.; Dahlstrom, Ulf; Filippatos, Gerasimos; Chioncel, Ovidiu; Crespo Leiro, Marisa; Drozdz, Jaroslaw; Fruhwald, Friedrich; Gullestad, Lars; Logeart, Damien; Metra, Marco; Parissis, John; Persson, Hans; Ponikowski, Piotr; Rauchhaus, Mathias; Voors, Adriaan A.; Nielsen, Olav Wendelboe; Zannad, Faiez; Tavazzi, Luigi

    2010-01-01

    The primary objective of the new ESC-HF Pilot Survey was to describe the clinical epidemiology of outpatients and inpatients with heart failure (HF) and the diagnostic/therapeutic processes applied across 12 participating European countries. This pilot study was specifically aimed at validating the

  7. EURObservational Research Programme: the Heart Failure Pilot Survey (ESC-HF Pilot)

    DEFF Research Database (Denmark)

    Maggioni, Aldo P; Dahlström, Ulf; Filippatos, Gerasimos;

    2010-01-01

    The primary objective of the new ESC-HF Pilot Survey was to describe the clinical epidemiology of outpatients and inpatients with heart failure (HF) and the diagnostic/therapeutic processes applied across 12 participating European countries. This pilot study was specifically aimed at validating...... the structure, performance, and quality of the data set, for continuing the survey into a permanent registry....

  8. Effects of sol aging on resistive switching behaviors of HfO{sub x} resistive memories

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Chih-Chieh, E-mail: cchsu@yuntech.edu.tw [Graduate School of Engineering Science and Technology, National Yunlin University of Science and Technology, Douliu 64002, Taiwan, ROC (China); Department of Electronic Engineering, National Yunlin University of Science and Technology, Douliu 64002, Taiwan, ROC (China); Graduate School of Electronic Engineering, National Yunlin University of Science and Technology, Douliu 64002, Taiwan, ROC (China); Sun, Jhen-Kai; Tsao, Che-Chang; Chen, Yu-Ting [Graduate School of Electronic Engineering, National Yunlin University of Science and Technology, Douliu 64002, Taiwan, ROC (China)

    2017-03-01

    This work investigates effects of long-term sol-aging time on sol-gel HfO{sub x} resistive random access memories (RRAMs). A nontoxic solvent of ethanol is used to replace toxic 2-methoxyethanol, which is usually used in sol-gel processes. The top electrodes are fabricated by pressing indium balls onto the HfO{sub x} surface rather than by using conventional sputtering or evaporation processes. The maximum process temperature is limited to be 100 ℃. Therefore, influences of plasma and high temperature on HfO{sub x} film can be avoided. Under this circumstance, effects of sol aging time on the HfO{sub x} films can be more clearly studied. The current conduction mechanisms in low and high electric regions of the HfO{sub x} RRAM are found to be dominated by Ohmic conduction and trap-filled space charge limited conduction (TF-SCLC), respectively. When the sol aging time increases, the resistive switching characteristic of the HfO{sub x} layer becomes unstable and the transition voltage from Ohmic conduction to TF-SCLC is also increased. This suggests that an exceedingly long aging time will give a HfO{sub x} film with more defect states. The XPS results are consistent with FTIR analysis and they can further explain the unstable HfO{sub x} resistive switching characteristic induced by sol aging.

  9. The effects of composition on mechanical properties of W-4Re-Hf-C alloys

    Science.gov (United States)

    Witzke, W. R.

    1974-01-01

    Studies were made of the effects of alloy composition on the mechanical behavior of as-worked W-4Re-Hf-C alloys containing up to about 0.8 mol % Hfc. Extracted second-phase particles were analyzed and related to alloy composition and creep strength. While strengthening is attributed to HfC particles, the presence of excess hafnium or carbon (above the calculated amounts for stoichiometric HfC) in swaged W-4Re-Hf-C alloys generally causes a reduction of the high-temperature (1930 C) tensile strength; maximum creep strength is, however, indicated for alloys with a slight (about 0.05 to 0.1 at. %) excess of hafnium. Particle strengthening is reduced by WC in solid solution with HfC for allow compositions with an excess of carbon. The low-temperature ductility of worked W-4Re-Hf-C alloys appears to be far more dependent on the amount of excess C or Hf present than on the HfC particle content in the range studies.

  10. First results on the sorption behaviour of Rutherfordium from HCl/HF containing aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Schumann, D.; Nitsche, H. [Technische Univ. Dresden (Germany); Taut, S. [Forschungszentrum Rossendorf e.V. (FZR), Dresden (Germany); Jost, D.T.; Gaeggeler, H.W. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Yakushev, A.B.; Buklanov, G.V.; Domanov, V.P.; Lien Din Thi [Joint Inst. for Nuclear Research, Dubna (Russian Federation); Kubica, B.; Misiak, R.; Szeglowski, Z. [NINP Cracow (Poland)

    1997-09-01

    Rutherfordium shows strong sorption on the cation exchanger DOWEX 50x8 at a concentration of 0.1 M HCl/10{sup -2} M HF. This shows that Rf behaves under these conditions differently from Hf and Zr and more like Th under these conditions. (author) 1 fig., 5 refs.

  11. Effects of sol aging on resistive switching behaviors of HfOx resistive memories

    Science.gov (United States)

    Hsu, Chih-Chieh; Sun, Jhen-Kai; Tsao, Che-Chang; Chen, Yu-Ting

    2017-03-01

    This work investigates effects of long-term sol-aging time on sol-gel HfOx resistive random access memories (RRAMs). A nontoxic solvent of ethanol is used to replace toxic 2-methoxyethanol, which is usually used in sol-gel processes. The top electrodes are fabricated by pressing indium balls onto the HfOx surface rather than by using conventional sputtering or evaporation processes. The maximum process temperature is limited to be 100 ℃. Therefore, influences of plasma and high temperature on HfOx film can be avoided. Under this circumstance, effects of sol aging time on the HfOx films can be more clearly studied. The current conduction mechanisms in low and high electric regions of the HfOx RRAM are found to be dominated by Ohmic conduction and trap-filled space charge limited conduction (TF-SCLC), respectively. When the sol aging time increases, the resistive switching characteristic of the HfOx layer becomes unstable and the transition voltage from Ohmic conduction to TF-SCLC is also increased. This suggests that an exceedingly long aging time will give a HfOx film with more defect states. The XPS results are consistent with FTIR analysis and they can further explain the unstable HfOx resistive switching characteristic induced by sol aging.

  12. The Modulation of Ionospheric Alfven Resonator on Heating HF Waves and the Doppler Effect

    Institute of Scientific and Technical Information of China (English)

    NiBin-bin; ZhaoZheng-yu; XieShu-guo

    2003-01-01

    The propagation of HF waves in IAR can produce many nonlinear effects, including the modulation effect of IAR on HF waves and the Doppler effect. To start with the dependence of the ionospheric electron temperature varia-tions on the Alfven resonant field, We discuss the mechanism of the modulation effect and lucubrate possible reasons for the Doppler effect. The results show that the Alfven resonant field can have an observable modulation effect on HF waves while its mechanism is quite different from that of Schumann resonant field on HF waves. The depth of modulation of IAR on HF waves has a quasi-quadratic relation with the Alfven field, which directly inspires the formation of cross-spectrum between ULF waves and HF waves and results in spectral peaks at some gyro-frequencies of IAR. With respect to the Doppler effect during the propagation of HF waves in IAR, it is mainly caused by the motion of the high-speed flyer and the drifting electrons and the frequency shift from the phase vari-ation of the reflected waves can be neglected when the frequency of HF incident wave is high enough.

  13. New PWM method and commutation strategy for HF-link converters for fuel cells and photovoltaics

    DEFF Research Database (Denmark)

    Ljusev, Petar; Andersen, Michael Andreas E.

    2005-01-01

    This paper presents a new PWM method and commutation strategy for HF-link converters, which leads to safe commutation of the load current in the output bidirectional bridge. The proposed implementation is independent of the particular HF-link converter topology and bidirectional switch selection...

  14. The first HF table, after heat treatment and ready to be machined in HEPCO, Arak (IRAN)

    CERN Multimedia

    Tiziano Camporesi

    2003-01-01

    The first HF support table 'load' tested by the team of people who have contributed to it from design to welding. This table will support the 240 tons of 1 HF detector and will integrate the raisers which will push it up to the beam line level. It is the first Iranian contribution to an HEP experiment.

  15. 47 CFR 73.758 - System specifications for digitally modulated emissions in the HF broadcasting service.

    Science.gov (United States)

    2010-10-01

    ... emissions in the HF broadcasting service. 73.758 Section 73.758 Telecommunication FEDERAL COMMUNICATIONS... § 73.758 System specifications for digitally modulated emissions in the HF broadcasting service. (a... digital audio broadcasting and datacasting are authorized. The RF requirements for the DRM system...

  16. Computed tomographic coronary angiography for patients with heart failure (CTA-HF): a randomized controlled trial (IMAGE HF Project 1-C).

    Science.gov (United States)

    Chow, Benjamin J W; Green, Rachel E; Coyle, Doug; Laine, Mika; Hanninen, Helena; Leskinen, Hanna; Rajda, Miroslav; Larose, Eric; Hartikainen, Juha; Hedman, Marja; Mielniczuk, Lisa; O'Meara, Eileen; deKemp, Robert A; Klein, Ran; Paterson, Ian; White, James A; Yla-Herttuala, Seppo; Leber, Alex; Tandon, Vikas; Lee, Ting; Al-Hesayen, Abdul; Hessian, Renee; Dowsley, Taylor; Kass, Malek; Kelly, Cathy; Garrard, Linda; Tardif, Jean-Claude; Knuuti, Juhani; Beanlands, Rob S; Wells, George A

    2013-12-26

    The prevalence of heart failure (HF) is rising in industrialized and developing countries. Though invasive coronary angiography (ICA) remains the gold standard for anatomical assessment of coronary artery disease in HF patients, alternatives are being sought. Computed tomographic coronary angiography (CTA) has emerged as an accurate non-invasive diagnostic tool for coronary artery disease (CAD) and has been demonstrated to have prognostic value. Whether or not CTA can be used in HF patients is unknown. Acknowledging the aging population, the growing prevalence of HF and the increasing financial burden of healthcare, we need to identify non-invasive diagnostic tests that are available, safe, accurate and cost-effective. The proposed study aims to provide insight into the efficacy of CTA in HF patients. A multicenter randomized controlled trial will enroll 250 HF patients requiring coronary anatomical definition. Enrolled patients will be randomized to either CTA or ICA (n = 125 per group) as the first test to define coronary anatomy. The primary outcomes will be collected to determine downstream resource utilization. Secondary outcomes will include the composite clinical events and major adverse cardiac events. In addition, the accuracy of CTA for detecting coronary anatomy and obstruction will be assessed in patients who subsequently undergo both CTA and ICA. It is expected that CTA will be a more cost-effective strategy for diagnosis: yielding similar outcomes with fewer procedural risks and improved resource utilization. ClinicalTrials.gov, NCT01283659. Team grant #CIF 99470.

  17. Evaluation of electron mobility in InSb quantum wells by means of percentage-impact

    Energy Technology Data Exchange (ETDEWEB)

    Mishima, T. D.; Edirisooriya, M.; Santos, M. B. [Homer L. Dodge Department of Physics and Astronomy, and Center for Semiconductor Physics in Nanostructure, University of Oklahoma, 440 W. Brooks St., Norman, OK 73019 (United States)

    2014-05-15

    In order to quantitatively analyze the contribution of each scattering factor toward the total carrier mobility, we use a new convenient figure-of-merit, named a percentage impact. The mobility limit due to a scattering factor, which is widely used to summarize a scattering analysis, has its own advantage. However, a mobility limit is not quite appropriate for the above purpose. A comprehensive understanding of the difference in contribution among many scattering factors toward the total carrier mobility can be obtained by evaluating percentage impacts of scattering factors, which can be straightforwardly calculated from their mobility limits and the total mobility. Our percentage impact analysis shows that threading dislocation is one of the dominant scattering factors for the electron transport in InSb quantum wells at room temperature.

  18. Dual-beam ELF wave generation as a function of power, frequency, modulation waveform, and receiver location

    Science.gov (United States)

    Agrawal, D.; Moore, R. C.

    2012-12-01

    Dual-beam ELF wave generation experiments performed at the High-frequency Active Auroral Research Program (HAARP) HF transmitter are used to investigate the dependence of the generated ELF wave magnitude on HF power, HF frequency, modulation waveform, and receiver location. During the experiments, two HF beams transmit simultaneously: one amplitude modulated (AM) HF beam modulates the conductivity of the lower ionosphere at ELF frequencies while a second HF beam broadcasts a continuous waveform (CW) signal, modifying the efficiency of ELF conductivity modulation and thereby the efficiency of ELF wave generation. We report experimental results for different ambient ionospheric conditions, and we interpret the observations in the context of a newly developed dual-beam HF heating model. A comparison between model predictions and experimental observations indicates that the theoretical model includes the essential physics involved in multifrequency HF heating of the lower ionosphere. In addition to the HF transmission parameters mentioned above, the model is used to predict the dependence of ELF wave magnitude on the polarization of the CW beam and on the modulation frequency of the modulated beam. We consider how these effects vary with ambientD-region electron density and electron temperature.

  19. Signal processing technique for randomly discontinuous spectra HF radar waveforms

    Institute of Scientific and Technical Information of China (English)

    张东坡; 刘兴钊

    2004-01-01

    A major problem with all high frequency (HF) radars is a relatively poor range resolution available due to many interference sources. To avoid the interferences in frequency domain and operate with wideband, the randomly discontinuous spectra (RDS) signal is employed. However, it results in high range sidelobes when matching the reflected echo, which is much more difficult for target detection. A new signal processing technique that is radically different from the conventional technique to lower range sidelobes is introduced. This method is based on suppressing the selfclutter of the radar range ambiguity function (AF) by mismatched filtering. An effective algorithm is adopted to solve the filter coefficients. Simulation results show that the peak sidelobe level can be reduced to -30dB and the achievable system bandwidth is about 400KHz. The technique is adaptable to practical radar systems and applicable for other realtime signal processing.

  20. Modification of polarization filtering technique in HF ground wave radar

    Institute of Scientific and Technical Information of China (English)

    Zhang Guoyi; Tan Zhongji; Wang Jiantao

    2006-01-01

    The polarization filter using three orthogonal linear polarization antennas can suppress more disturbances than the polarization filter using two orthogonal linear polarization antennas in HF ground wave radar. But the algorithm of the threedimension filter is relatively complicated and not suitable for real-time processing. It can't use linear and nonlinear polarization vector translation technique directly. A modified polarization filter which is simple and has same suppressing ability as the three-dimension polarization filter is given. It only has half parameters of the primary one. Some problems about estimation of polarization parameters and selection of disturbances are discussed. A method of holding the phase of radar backscatter signal constantly is put forward so that unstationary disturbance signal can be processed.

  1. Toward an european Med HF-radar coastal monitoring

    Science.gov (United States)

    Molcard, A.; Fraunie, P.

    2010-12-01

    The monitoring of coastal areas through HF radar is developping in the european Mediterranean coasts, through national and international projects. Surface current maps may be used for process studies, forecast correction through assimilation, or for practical applications in transport studies (jellyfish, oil-spill, search-and-rescue operations). Results of radar campaigns in the North-western Mediterranean (evidence of mesoscale eddy in the Gulf of Lions and identification of dynamical structures by FSLE in the Ligurian Sea) are shown, as well as techniques for current reconstruction using a single site. A new inter-regional european project started in summer 2010, regrouping 5 countries for an integrated oil-spill coastal awarness network is presented.

  2. Win percentage: a novel measure for assessing the suitability of machine classifiers for biological problems

    Science.gov (United States)

    2012-01-01

    Background Selecting an appropriate classifier for a particular biological application poses a difficult problem for researchers and practitioners alike. In particular, choosing a classifier depends heavily on the features selected. For high-throughput biomedical datasets, feature selection is often a preprocessing step that gives an unfair advantage to the classifiers built with the same modeling assumptions. In this paper, we seek classifiers that are suitable to a particular problem independent of feature selection. We propose a novel measure, called "win percentage", for assessing the suitability of machine classifiers to a particular problem. We define win percentage as the probability a classifier will perform better than its peers on a finite random sample of feature sets, giving each classifier equal opportunity to find suitable features. Results First, we illustrate the difficulty in evaluating classifiers after feature selection. We show that several classifiers can each perform statistically significantly better than their peers given the right feature set among the top 0.001% of all feature sets. We illustrate the utility of win percentage using synthetic data, and evaluate six classifiers in analyzing eight microarray datasets representing three diseases: breast cancer, multiple myeloma, and neuroblastoma. After initially using all Gaussian gene-pairs, we show that precise estimates of win percentage (within 1%) can be achieved using a smaller random sample of all feature pairs. We show that for these data no single classifier can be considered the best without knowing the feature set. Instead, win percentage captures the non-zero probability that each classifier will outperform its peers based on an empirical estimate of performance. Conclusions Fundamentally, we illustrate that the selection of the most suitable classifier (i.e., one that is more likely to perform better than its peers) not only depends on the dataset and application but also on the

  3. The electronic structure of HfF5- and WF5-

    Science.gov (United States)

    Chen, Hongshan; Andersson, Pontus; Lindahl, Anton O.; Hanstorp, Dag

    2011-08-01

    The electronic structure of HfF5-, WF5- and the related species HfF n and WF n is studied using ab initio methods. Computation reveals that the hafnium fluorides are much more stable than the corresponding tungsten fluorides. The detachment energy of HfF5- is 8.8 eV, whereas the corresponding quantity of WF5- is only 3.9 eV. These results show that WF5- can be photodetached while HfF5- is unaffected, and so it is possible by using photodetachment to suppress the interfering isobar 182W in the ion beam of 182Hf. Such information is the precondition for the successful implementation of a future photodetachment process in Accelerator Mass Spectrometry.

  4. Effect of hydrofluoric acid (HF) concentration to pores size diameter of silicon membrane.

    Science.gov (United States)

    Burham, Norhafizah; Hamzah, Azrul Azlan; Majlis, Burhanuddin Yeop

    2014-01-01

    This paper studies parameters which affect the pore size diameter of a silicon membrane. Electrochemical etching is performed in characterise the parameter involved in this process. The parameter has been studied is volume ratio of hydrofluoric acid (HF) and ethanol as an electrolyte aqueous for electrochemical etch. This electrolyte aqueous solution has been mixed between HF and ethanol with volume ratio 3:7, 5:5, 7:3 and 9:1. As a result, the higher volume of HF in this electrolyte gives the smallest pore size diameter compared to the lower volume of HF. These samples have been dipped into HF and ethanol electrolyte aqueous with supplied 25 mA/cm2 current density for 20, 30, 40, and 50 minutes. The samples will inspect under Scanning Electron Microscope (SEM) to execute the pore formations on silicon membrane surface.

  5. Suspended HfO{sub 2} photonic crystal slab on III-nitride/Si platform

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yongjin; Feng, Jiao; Cao, Ziping; Zhu, Hongbo [Nanjing University of Posts and Telecommunications, Grueenberg Research Centre, Nanjing, Jiang-Su (China)

    2014-06-15

    We present here the fabrication of suspended hafnium oxide (HfO{sub 2}) photonic crystal slab on a III-nitride/Si platform. The calculations are performed to model the suspended HfO{sub 2} photonic crystal slab. Aluminum nitride (AlN) film is employed as the sacrificial layer to form air gap. Photonic crystal patterns are defined by electron beam lithography and transferred into HfO{sub 2} film, and suspended HfO{sub 2} photonic crystal slab is achieved on a III-nitride/Si platform through wet-etching of AlN layer in the alkaline solution. The method is promising for the fabrication of suspended HfO{sub 2} nanostructures incorporating into a III-nitride/Si platform, or acting as the template for epitaxial growth of III-nitride materials. (orig.)

  6. Crystal structure of Si-doped HfO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Lili [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); School of Information Science and Technology, Northwest University, Xi' an 710127 (China); Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611 (United States); Nelson, Matthew; Fancher, Chris M. [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Aldridge, Henry [Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611 (United States); Iamsasri, Thanakorn; Forrester, Jennifer S.; Jones, Jacob L., E-mail: jacobjones@ncsu.edu [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611 (United States); Nishida, Toshikazu [Department of Electrical and Computer Engineering, University of Florida, Gainesville, Florida 32611 (United States); Moghaddam, Saeed [Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, Florida 32611 (United States)

    2014-01-21

    Si-doped HfO{sub 2} was prepared by solid state synthesis of the starting oxides. Using Rietveld refinement of high resolution X-ray diffraction patterns, a substitutional limit of Si in HfO{sub 2} was determined as less than 9 at. %. A second phase was identified as Cristobalite (SiO{sub 2}) rather than HfSiO{sub 4}, the latter of which would be expected from existing SiO{sub 2}-HfO{sub 2} phase diagrams. Crystallographic refinement with increased Si-dopant concentration in monoclinic HfO{sub 2} shows that c/b increases, while β decreases. The spontaneous strain, which characterizes the ferroelastic distortion of the unit cell, was calculated and shown to decrease with increasing Si substitution.

  7. Tsunami Arrival Detection with High Frequency (HF Radar

    Directory of Open Access Journals (Sweden)

    Donald Barrick

    2012-05-01

    Full Text Available Quantitative real-time observations of a tsunami have been limited to deep-water, pressure-sensor observations of changes in the sea surface elevation and observations of sea level fluctuations at the coast, which are essentially point measurements. Constrained by these data, models have been used for predictions and warning of the arrival of a tsunami, but to date no system exists for local detection of an actual incoming wave with a significant warning capability. Networks of coastal high frequency (HF-radars are now routinely observing surface currents in many countries. We report here on an empirical method for the detection of the initial arrival of a tsunami, and demonstrate its use with results from data measured by fourteen HF radar sites in Japan and USA following the magnitude 9.0 earthquake off Sendai, Japan, on 11 March 2011. The distance offshore at which the tsunami can be detected, and hence the warning time provided, depends on the bathymetry: the wider the shallow continental shelf, the greater this time. We compare arrival times at the radars with those measured by neighboring tide gauges. Arrival times measured by the radars preceded those at neighboring tide gauges by an average of 19 min (Japan and 15 min (USA The initial water-height increase due to the tsunami as measured by the tide gauges was moderate, ranging from 0.3 to 2 m. Thus it appears possible to detect even moderate tsunamis using this method. Larger tsunamis could obviously be detected further from the coast. We find that tsunami arrival within the radar coverage area can be announced 8 min (i.e., twice the radar spectral time resolution after its first appearance. This can provide advance warning of the tsunami approach to the coastline locations.

  8. Effects of Aloe vera on dressing percentage and haemato-biochemidal parameters of broiler chickens

    OpenAIRE

    Jagmohan Singh; K.M. Koley; Khushboo Chandrakar; Nileshkumar S. Pagrut

    2013-01-01

    Aim: To evaluate the effects of Aloe vera on dressing percentage and hemato-biochemical parameters of broiler chickens.Materials and Methods: A total of 90 chicks were used in this study. They were randomly allocated into 3 treatment groups.Fresh Aloe vera leaf juice (ALJ) was prepared and administered to the test group T3 at the rate of 20 g/Lin drinking water daily.This study was carried out for 42 days. Dressing percentage and hemato-biochemical parameters were recorded at the end ofexperi...

  9. PI/PID controller design based on IMC and percentage overshoot specification to controller setpoint change.

    Science.gov (United States)

    Ali, Ahmad; Majhi, Somanath

    2009-01-01

    In this work, the normalized Internal Model Control (IMC) filter time constant is designed to achieve a specified value of the maximum sensitivity for stable first and second order plus time delay process models, respectively. Since a particular value of the maximum sensitivity results in an almost constant percentage overshoot to controller setpoint change, an empirical relationship between the normalized IMC filter time constant and percentage overshoot is presented. The main advantage of the proposed method is that only a user-defined overshoot is required to design a PI/PID controller. Simulation examples are given to demonstrate the value of the proposed method.

  10. Alternatives to accuracy and bias metrics based on percentage errors for radiation belt modeling applications

    Energy Technology Data Exchange (ETDEWEB)

    Morley, Steven Karl [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-07-01

    This report reviews existing literature describing forecast accuracy metrics, concentrating on those based on relative errors and percentage errors. We then review how the most common of these metrics, the mean absolute percentage error (MAPE), has been applied in recent radiation belt modeling literature. Finally, we describe metrics based on the ratios of predicted to observed values (the accuracy ratio) that address the drawbacks inherent in using MAPE. Specifically, we define and recommend the median log accuracy ratio as a measure of bias and the median symmetric accuracy as a measure of accuracy.

  11. The Thermodynamic Characterization of ZrCo–H, HfCo−H, HfNi−H and Zr{sub 1–x}HfxNi(Co) Alloy–H Systems

    Energy Technology Data Exchange (ETDEWEB)

    Flanagan, Ted B., E-mail: ted.flanagan@uvm.edu; Noh, Hak; Luo, Suifang

    2016-08-25

    ZrCo and HfCo intermetallic compounds have the same cubic (CsCl-type) structure and their ternary (Zr{sub 1−x}Hf{sub x})Co alloys are also cubic. ZrNi and HfNi intermetallic compounds have the orthorhombic structure (CrB-type) and the ternary (Zr{sub 1−x}Hf{sub x})Ni alloys also have this structure. Thermodynamic data for hydride formation and decomposition in ZrCo, HfCo and HfNi intermetallic compounds have been determined from reaction calorimetry and from pressure-composition isotherms. Thermodynamic data have been determined for the three ternary alloys: (Zr{sub 0.75}Hf{sub 0.25})Co, (Zr{sub 0.50}Hf{sub 0.50})Co, and (Zr{sub 0.25}Hf{sub 0.75})Co and the four ternary alloys: (Zr{sub 0.875}Hf{sub 0.125})Ni, (Zr{sub 0.75}Hf{sub 0.25})Ni, (Zr{sub 0.50}Hf{sub 0.50})Ni, and (Zr{sub 0.25}Hf{sub 0.75})Ni. This offers the opportunity to learn how the thermodynamic properties of the ternary alloy-H systems change with the stoichiometry of alloys with the same structure. - Highlights: • Calorimetric enthalpies determined for H absorption by ZrCo, HfCo, HfNi are determined. • Ternary alloys, e.g., Zr{sub 1−x}Hf{sub x}Ni, prepared and characterized by x-ray diffraction. • Isotherms for the ternary alloys give thermodynamic parameters for H solution.

  12. Single layer of Ge quantum dots in HfO2 for floating gate memory capacitors.

    Science.gov (United States)

    Lepadatu, A M; Palade, C; Slav, A; Maraloiu, A V; Lazanu, S; Stoica, T; Logofatu, C; Teodorescu, V S; Ciurea, M L

    2017-04-28

    High performance trilayer memory capacitors with a floating gate of a single layer of Ge quantum dots (QDs) in HfO2 were fabricated using magnetron sputtering followed by rapid thermal annealing (RTA). The layer sequence of the capacitors is gate HfO 2/floating gate of single layer of Ge QDs in HfO 2/tunnel HfO 2/p-Si wafers. Both Ge and HfO2 are nanostructured by RTA at moderate temperatures of 600-700 °C. By nanostructuring at 600 °C, the formation of a single layer of well separated Ge QDs with diameters of 2-3 nm at a density of 4-5 × 10(15) m(-2) is achieved in the floating gate (intermediate layer). The Ge QDs inside the intermediate layer are arranged in a single layer and are separated from each other by HfO2 nanocrystals (NCs) about 8 nm in diameter with a tetragonal/orthorhombic structure. The Ge QDs in the single layer are located at the crossing of the HfO2 NCs boundaries. In the intermediate layer, besides Ge QDs, a part of the Ge atoms is segregated by RTA at the HfO2 NCs boundaries, while another part of the Ge atoms is present inside the HfO2 lattice stabilizing the tetragonal/orthorhombic structure. The fabricated capacitors show a memory window of 3.8 ± 0.5 V and a capacitance-time characteristic with 14% capacitance decay in the first 3000-4000 s followed by a very slow capacitance decrease extrapolated to 50% after 10 years. This high performance is mainly due to the floating gate of a single layer of well separated Ge QDs in HfO2, distanced from the Si substrate by the tunnel oxide layer with a precise thickness.

  13. Garnet effect on Nd-Hf isotope decoupling: Evidence from the Jinfosi batholith, Northern Tibetan Plateau

    Science.gov (United States)

    Huang, Hui; Niu, Yaoling; Mo, Xuanxue

    2017-03-01

    The initial Nd and Hf isotope ratios of a 420 Ma post-collisional dioritic-granitic batholith from the Northern Tibetan plateau define a negative trend above and orthogonal to the ԐHf(t)-ԐNd(t) terrestrial array. This uncommon trend offers an insight into the origin of the puzzling Nd-Hf isotope decoupling in the crustal rocks. On this trend, samples depleted in heavy rare earth elements (HREEs, i.e., [Dy/Yb]N ≫ 1) deviate most from the terrestrial array whereas samples with flat HREEs (i.e., [Dy/Yb]N ≥ 1) deviate less or plot within the terrestrial array, pointing to the controlling effect of garnet in the magma source. Ancient garnet-bearing residues after melt extraction will have elevated Lu/Hf ratios and can evolve with time to produce high ԐHf(t) at a low ԐNd(t) value. Mixing of melts derived from such source lithologies (high Lu/Hf) with melts possessing a within-terrestrial array Nd-Hf isotopic composition (low Lu/Hf) best explains the observed trend orthogonal to the terrestrial array. The samples from the Jinfosi batholith with the most decoupled Nd-Hf isotope compositions require a larger degree (> 40%) and ancient (i.e., ≥ 1.8 Gyr) previous melt extraction from their source. It follows that the ancient melts with depleted HREEs complementary to those garnet-bearing residues should have low ԐHf values and plot below the terrestrial array, which is indeed shown by some Archean/Paleoproterozic TTGs.

  14. Mixing and melt sources in the Miocene Aztec Wash pluton (Nevada, USA) as revealed by zircon Hf and O and whole rock Sr, Nd, and Hf isotopes

    Science.gov (United States)

    Ryan, M.; Miller, J. S.; Miller, C. F.; Bromley, S.; Davies, G. R.; Schmitt, A. K.

    2011-12-01

    The 15.6 Ma Aztec Wash Pluton (AWP) is one of several Miocene intrusions located within the northern Colorado River extensional corridor. Extensive E-W tilting of fault blocks has exposed the pluton from the roof to 5 km structural depth. Earlier field and petrologic studies subdivided the AWP into two distinct zones: (1) a Granite Zone (GZ) comprised of relatively homogeneous granite with subtle differences in textures and mineralogy; (2) a Heterogeneous Zone (HZ), which interfingers the GZ, contains evidence for mafic and felsic magma input with a wide compositional range (42-78 wt% SiO2), and abundant field evidence for hybridization. Previous whole rock geochemistry and zircon trace element analyses indicated that compositional variation was produced by multi-component mixing between mafic and felsic melts within the HZ. New whole rock Sr, Nd, and Hf isotope data from the HZ show that all rocks (including high-silica granites) formed by mixing Precambrian crust and enriched mantle, with mixtures having a large mantle fraction (≥50%). New Hf (n=189) and O (n=241) isotope analyses of zircon from samples in the HZ confirm these melt sources and provide a broader perspective on hybridization processes within the AWP. Zircon grains from all samples show heterogeneous Hf and O isotopic compositions (-5 to -18 ɛHf; 4.5-7.5% δ18O), but despite the clear signature of Precambrian crust in the whole rock data, obvious Precambrian zircons (or cores) were mostly absent; only one zircon was clearly Precambrian (ɛHf = -25). Resolvable intragrain variability is relatively limited (including the Precambrian grain, which is unzoned). Zircons from hand samples and from compositional groups also show heterogeneous ɛHf and δ18O values, although the spreads are more restricted than in the whole data set (6-10 ɛHf in granites, 5-7 ɛHf in intermediate "hybrids", 5-6 ɛHf in gabbro/diorite sheets). Oxygen isotope values for the zircons also show intra-handsample heterogeneity

  15. Computational-Experimental Processing of Boride/Carbide Composites by Reactive Infusion of Hf Alloy Melts into B4C

    Science.gov (United States)

    2015-09-16

    elements from the Hf family (i.e., Hf, Ti and Zr ) into a capillary to understand the effects of surface tension and viscosity during processing of melts...project primarily investigated computationally the infusion of liquid elements from the Hf family (i.e., Hf, Ti and Zr ) into a capillary to understand the... effects of surface tension and viscosity during processing of melts with a packed bed of B4C to form boride-carbide precipitates. Although the

  16. Power electronics solution to dust emissions from thermal power plants

    Directory of Open Access Journals (Sweden)

    Vukosavić Slobodan

    2010-01-01

    Full Text Available Thermal power stations emit significant amounts of fly ash and ultra fine particles into the atmosphere. Electrostatic precipitators (ESP or electro filters remove flying ashes and fine particles from the flue gas before passing the gas into the chimney. Maximum allowable value of dust is 50 mg/m3 and it requires that the efficiency of the ESPs better than 99 %, which calls for an increase of active surface of the electrodes, hence increasing the filter volume and the weight of steel used for the filter. In previous decades, electrostatic precipitators in thermal power plants were fed by thyristor controlled, single phase fed devices having a high degree of reliability, but with a relatively low collection efficiency, hence requiring large effective surface of the collection plates and a large weight of steel construction in order to achieve the prescribed emission limits. Collection efficiency and energy efficiency of the electrostatic precipitator can be increased by applying high frequency high voltage power supply (HF HV. Electrical engineering faculty of the University of Belgrade (ETF has developed technology and HF HV equipment for the ESP power supply. This solution was subjected to extensive experimental investigation at TE Morava from 2008 to 2010. High frequency power supply is proven to reduce emission two times in controlled conditions while increasing energy efficiency of the precipitator, compared to the conventional thyristor controlled 50Hz supply. Two high frequency high voltage unit AR70/1000 with parameters 70 kV and 1000 mA are installed at TE Morava and thoroughly testes. It was found that the HF HV power supply of the ESP at TE Morava increases collection efficiency so that emission of fine particles and flying ashes are halved, brought down to only 50 % of the emissions encountered with conventional 50 Hz thyristor driven power supplies. On the basis of this study, conclusion is drawn that the equipment comprising HF HV

  17. 78 FR 36183 - State Allotment Percentages for the Drinking Water State Revolving Fund Program

    Science.gov (United States)

    2013-06-17

    ... AGENCY State Allotment Percentages for the Drinking Water State Revolving Fund Program AGENCY... Protection Agency (EPA) is announcing the revised Drinking Water State Revolving Fund (DWSRF) allotments that... enacted. These allotments reflect the results from EPA's most recent Drinking Water Infrastructure...

  18. Brief Report: On the Concordance Percentages for Autistic Spectrum Disorder of Twins

    Science.gov (United States)

    Bohm, Henry V.; Stewart, Melbourne G.

    2009-01-01

    In the development of genetic theories of Autistic Spectrum Disorder (ASD) various characteristics of monozygotic (MZ) and dizygotic (DZ) twins are often considered. This paper sets forth a possible refinement in the interpretation of the MZ twin concordance percentages for ASD underlying such genetic theories, and, drawing the consequences from…

  19. Discipline-Related Marking Behaviour Using Percentages: A Potential Cause of Inequity in Assessment.

    Science.gov (United States)

    Briggs, Paul; And Others

    1999-01-01

    Analysis of percentage grade distributions in 11 subject areas at seven English universities over three years found three types of grade distributions characteristic of specific subject areas: (1) English and History; (2) Biology, Business Studies, Fine Art, French, Law, and Sociology; and (3) Computer Studies and Mathematics. Grade distribution…

  20. 13 CFR 120.210 - What percentage of a loan may SBA guarantee?

    Science.gov (United States)

    2010-01-01

    ... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false What percentage of a loan may SBA guarantee? 120.210 Section 120.210 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION BUSINESS... percent, except as otherwise authorized by law....

  1. Preeclampsia is Associated with lower Percentages of Regulatory T Cells in Maternal Blood

    NARCIS (Netherlands)

    Prins, Jelmer R.; Boelens, Hendrik M.; Heimweg, Janneke; Van der Heide, Sicco; Dubois, Anthony E.; Van Oosterhout, Antoon J.; Erwich, Jan Jaap H. M.

    2009-01-01

    Objective: Immunological mechanisms are involved in the pathophysiology of preeclampsia. During pregnancy there is an increase in regulatory T (Treg) cells, which has an important role in regulating tolerance to the immunologically distinct fetus. We hypothesised that percentages of Treg cells are

  2. Absolute and Relative Reliability of Percentage of Syllables Stuttered and Severity Rating Scales

    Science.gov (United States)

    Karimi, Hamid; O'Brian, Sue; Onslow, Mark; Jones, Mark

    2014-01-01

    Purpose: Percentage of syllables stuttered (%SS) and severity rating (SR) scales are measures in common use to quantify stuttering severity and its changes during basic and clinical research conditions. However, their reliability has not been assessed with indices measuring both relative and absolute reliability. This study was designed to provide…

  3. 7 CFR 993.55 - Application of salable and reserve percentages after end of crop year.

    Science.gov (United States)

    2010-01-01

    ... end of crop year. 993.55 Section 993.55 Agriculture Regulations of the Department of Agriculture....55 Application of salable and reserve percentages after end of crop year. The salable and reserve... 30613, May 27, 2005, § 993.55 was suspended indefinitely. ...

  4. 13 CFR 108.1840 - Computation of NMVC Company's Capital Impairment Percentage.

    Science.gov (United States)

    2010-01-01

    ... Capital Impairment Percentage. 108.1840 Section 108.1840 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION NEW MARKETS VENTURE CAPITAL (âNMVCâ) PROGRAM NMVC Company's Noncompliance With Terms of Leverage Computation of Nmvc Company's Capital Impairment § 108.1840 Computation of NMVC Company's Capital...

  5. Dosimetric characterization of 3D printed bolus at different infill percentage for external photon beam radiotherapy.

    Science.gov (United States)

    Ricotti, Rosalinda; Ciardo, Delia; Pansini, Floriana; Bazani, Alessia; Comi, Stefania; Spoto, Ruggero; Noris, Samuele; Cattani, Federica; Baroni, Guido; Orecchia, Roberto; Vavassori, Andrea; Alicja Jereczek-Fossa, Barbara

    2017-07-01

    3D printing is rapidly evolving and further assessment of materials and technique is required for clinical applications. We evaluated 3D printed boluses with acrylonitrile butadiene styrene (ABS) and polylactide (PLA) at different infill percentage. A low-cost 3D printer was used. The influence of the air inclusion within the 3D printed boluses was assessed thoroughly both with treatment planning system (TPS) and with physical measurements. For each bolus, two treatment plans were calculated with Monte Carlo algorithm, considering the computed tomography (CT) scan of the 3D printed bolus or modelling the 3D printed bolus as a virtual bolus structure with a homogeneous density. Depth dose measurements were performed with Gafchromic films. High infill percentage corresponds to high density and high homogeneity within bolus material. The approximation of the bolus in the TPS as a homogeneous material is satisfying for infill percentages greater than 20%. Measurements performed with PLA boluses are more comparable to the TPS calculated profiles. For boluses printed at 40% and 60% infill, the discrepancies between calculated and measured dose distribution are within 5%. 3D printing technology allows modulating the shift of the build-up region by tuning the infill percentage of the 3D printed bolus in order to improve superficial target coverage. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  6. Preeclampsia is Associated with lower Percentages of Regulatory T Cells in Maternal Blood

    NARCIS (Netherlands)

    Prins, Jelmer R.; Boelens, Hendrik M.; Heimweg, Janneke; Van der Heide, Sicco; Dubois, Anthony E.; Van Oosterhout, Antoon J.; Erwich, Jan Jaap H. M.

    2009-01-01

    Objective: Immunological mechanisms are involved in the pathophysiology of preeclampsia. During pregnancy there is an increase in regulatory T (Treg) cells, which has an important role in regulating tolerance to the immunologically distinct fetus. We hypothesised that percentages of Treg cells are d

  7. New loci for body fat percentage reveal link between adiposity and cardiometabolic disease risk

    NARCIS (Netherlands)

    Lu, Yingchang; Day, Felix R; Gustafsson, Stefan; Buchkovich, Martin L; Na, Jianbo; Bataille, Veronique; Cousminer, Diana L; Dastani, Zari; Drong, Alexander W; Esko, Tõnu; Evans, David M; Falchi, Mario; Feitosa, Mary F; Ferreira, Teresa; Hedman, Åsa K; Haring, Robin; Hysi, Pirro G; Iles, Mark M; Justice, Anne E; Kanoni, Stavroula; Lagou, Vasiliki; Li, Rui; Li, Xin; Locke, Adam; Lu, Chen; Mägi, Reedik; Perry, John R B; Pers, Tune H; Qi, Qibin; Sanna, Marianna; Schmidt, Ellen M; Scott, William R; Shungin, Dmitry; Teumer, Alexander; Vinkhuyzen, Anna A E; Walker, Ryan W; Westra, Harm-Jan; Zhang, Mingfeng; Zhang, Weihua; Zhao, Jing Hua; Zhu, Zhihong; Afzal, Uzma; Ahluwalia, Tarunveer Singh; Bakker, Stephan J L; Bellis, Claire; Bonnefond, Amélie; Borodulin, Katja; Buchman, Aron S; Cederholm, Tommy; Choh, Audrey C; Choi, Hyung Jin; Curran, Joanne E; de Groot, Lisette C P G M; De Jager, Philip L; Dhonukshe-Rutten, Rosalie A M; Enneman, Anke W; Eury, Elodie; Evans, Daniel S; Forsen, Tom; Friedrich, Nele; Fumeron, Frédéric; Garcia, Melissa E; Gärtner, Simone; Han, Bok-Ghee; Havulinna, Aki S; Hayward, Caroline; Hernandez, Dena; Hillege, Hans; Ittermann, Till; Kent, Jack W; Kolcic, Ivana; Laatikainen, Tiina; Lahti, Jari; Mateo Leach, Irene; Lee, Christine G; Lee, Jong-Young; Liu, Tian; Liu, Youfang; Lobbens, Stéphane; Loh, Marie; Lyytikäinen, Leo-Pekka; Medina-Gomez, Carolina; Michaëlsson, Karl; Nalls, Mike A; Nielson, Carrie M; Oozageer, Laticia; Pascoe, Laura; Paternoster, Lavinia; Polašek, Ozren; Ripatti, Samuli; Sarzynski, Mark A; Shin, Chan Soo; Narančić, Nina Smolej; Spira, Dominik; Srikanth, Priya; Steinhagen-Thiessen, Elisabeth; Sung, Yun Ju; Swart, Karin M A; Taittonen, Leena; Tanaka, Toshiko; Tikkanen, Emmi; van der Velde, Nathalie; van Schoor, Natasja M; Verweij, Niek; Wright, Alan F; Yu, Lei; Zmuda, Joseph M; Eklund, Niina; Forrester, Terrence; Grarup, Niels; Jackson, Anne U; Kristiansson, Kati; Kuulasmaa, Teemu; Kuusisto, Johanna; Lichtner, Peter; Luan, Jian'an; Mahajan, Anubha; Männistö, Satu; Palmer, Cameron D; Ried, Janina S; Scott, Robert A; Stancáková, Alena; Wagner, Peter J; Demirkan, Ayse; Döring, Angela; Gudnason, Vilmundur; Kiel, Douglas P; Kühnel, Brigitte; Mangino, Massimo; Mcknight, Barbara; Menni, Cristina; O'Connell, Jeffrey R; Oostra, Ben A; Shuldiner, Alan R; Song, Kijoung; Vandenput, Liesbeth; van Duijn, Cornelia M; Vollenweider, Peter; White, Charles C; Boehnke, Michael; Boettcher, Yvonne; Cooper, Richard S; Forouhi, Nita G; Gieger, Christian; Grallert, Harald; Hingorani, Aroon; Jørgensen, Torben; Jousilahti, Pekka; Kivimaki, Mika; Kumari, Meena; Laakso, Markku; Langenberg, Claudia; Linneberg, Allan; Luke, Amy; Mckenzie, Colin A; Palotie, Aarno; Pedersen, Oluf; Peters, Annette; Strauch, Konstantin; Tayo, Bamidele O; Wareham, Nicholas J; Bennett, David A; Bertram, Lars; Blangero, John; Blüher, Matthias; Bouchard, Claude; Campbell, Harry; Cho, Nam H; Cummings, Steven R; Czerwinski, Stefan A; Demuth, Ilja; Eckardt, Rahel; Eriksson, Johan G; Ferrucci, Luigi; Franco, Oscar H; Froguel, Philippe; Gansevoort, Ron T; Hansen, Torben; Harris, Tamara B; Hastie, Nicholas; Heliövaara, Markku; Hofman, Albert; Jordan, Joanne M; Jula, Antti; Kähönen, Mika; Kajantie, Eero; Knekt, Paul B; Koskinen, Seppo; Kovacs, Peter; Lehtimäki, Terho; Lind, Lars; Liu, Yongmei; Orwoll, Eric S; Osmond, Clive; Perola, Markus; Pérusse, Louis; Raitakari, Olli T; Rankinen, Tuomo; Rao, D C; Rice, Treva K; Rivadeneira, Fernando; Rudan, Igor; Salomaa, Veikko; Sørensen, Thorkild I A; Stumvoll, Michael; Tönjes, Anke; Towne, Bradford; Tranah, Gregory J; Tremblay, Angelo; Uitterlinden, André G; van der Harst, Pim; Vartiainen, Erkki; Viikari, Jorma S; Vitart, Veronique; Vohl, Marie-Claude; Völzke, Henry; Walker, Mark; Wallaschofski, Henri; Wild, Sarah; Wilson, James F; Yengo, Loïc; Bishop, D Timothy; Borecki, Ingrid B; Chambers, John C; Cupples, L Adrienne; Dehghan, Abbas; Deloukas, Panos; Fatemifar, Ghazaleh; Fox, Caroline; Furey, Terrence S; Franke, Lude; Han, Jiali; Hunter, David J; Karjalainen, Juha; Karpe, Fredrik; Kaplan, Robert C; Kooner, Jaspal S; McCarthy, Mark I; Murabito, Joanne M; Morris, Andrew P; Bishop, Julia A N; North, Kari E; Ohlsson, Claes; Ong, Ken K; Prokopenko, Inga; Richards, J Brent; Schadt, Eric E; Spector, Tim D; Widén, Elisabeth; Willer, Cristen J; Yang, Jian; Ingelsson, Erik; Mohlke, Karen L; Hirschhorn, Joel N; Pospisilik, John Andrew; Zillikens, M Carola; Lindgren, Cecilia; Kilpeläinen, Tuomas Oskari; Loos, Ruth J F

    2016-01-01

    To increase our understanding of the genetic basis of adiposity and its links to cardiometabolic disease risk, we conducted a genome-wide association meta-analysis of body fat percentage (BF%) in up to 100,716 individuals. Twelve loci reached genome-wide significance (P<5 × 10(-8)), of which eight w

  8. New loci for body fat percentage reveal link between adiposity and cardiometabolic disease risk

    NARCIS (Netherlands)

    Lu, Yingchang; Day, Felix R; Gustafsson, Stefan; Buchkovich, Martin L; Na, Jianbo; Bataille, Veronique; Cousminer, Diana L; Dastani, Zari; Drong, Alexander W; Esko, Tõnu; Evans, David M; Falchi, Mario; Feitosa, Mary F; Ferreira, Teresa; Hedman, Åsa K; Haring, Robin; Hysi, Pirro G; Iles, Mark M; Justice, Anne E; Kanoni, Stavroula; Lagou, Vasiliki; Li, Rui; Li, Xin; Locke, Adam; Lu, Chen; Mägi, Reedik; Perry, John R B; Pers, Tune H; Qi, Qibin; Sanna, Marianna; Schmidt, Ellen M; Scott, William R; Shungin, Dmitry; Teumer, Alexander; Vinkhuyzen, Anna A E; Walker, Ryan W; Westra, Harm-Jan; Zhang, Mingfeng; Zhang, Weihua; Zhao, Jing Hua; Zhu, Zhihong; Afzal, Uzma; Ahluwalia, Tarunveer Singh; Bakker, Stephan J L; Bellis, Claire; Bonnefond, Amélie; Borodulin, Katja; Buchman, Aron S; Cederholm, Tommy; Choh, Audrey C; Choi, Hyung Jin; Curran, Joanne E; de Groot, Lisette C P G M; De Jager, Philip L; Dhonukshe-Rutten, Rosalie A M; Enneman, Anke W; Eury, Elodie; Evans, Daniel S; Forsen, Tom; Friedrich, Nele; Fumeron, Frédéric; Garcia, Melissa E; Gärtner, Simone; Han, Bok-Ghee; Havulinna, Aki S; Hayward, Caroline; Hernandez, Dena; Hillege, Hans; Ittermann, Till; Kent, Jack W; Kolcic, Ivana; Laatikainen, Tiina; Lahti, Jari; Mateo Leach, Irene; Lee, Christine G; Lee, Jong-Young; Liu, Tian; Liu, Youfang; Lobbens, Stéphane; Loh, Marie; Lyytikäinen, Leo-Pekka; Medina-Gomez, Carolina; Michaëlsson, Karl; Nalls, Mike A; Nielson, Carrie M; Oozageer, Laticia; Pascoe, Laura; Paternoster, Lavinia; Polašek, Ozren; Ripatti, Samuli; Sarzynski, Mark A; Shin, Chan Soo; Narančić, Nina Smolej; Spira, Dominik; Srikanth, Priya; Steinhagen-Thiessen, Elisabeth; Sung, Yun Ju; Swart, Karin M A; Taittonen, Leena; Tanaka, Toshiko; Tikkanen, Emmi; van der Velde, Nathalie; van Schoor, Natasja M; Verweij, Niek; Wright, Alan F; Yu, Lei; Zmuda, Joseph M; Eklund, Niina; Forrester, Terrence; Grarup, Niels; Jackson, Anne U; Kristiansson, Kati; Kuulasmaa, Teemu; Kuusisto, Johanna; Lichtner, Peter; Luan, Jian'an; Mahajan, Anubha; Männistö, Satu; Palmer, Cameron D; Ried, Janina S; Scott, Robert A; Stancáková, Alena; Wagner, Peter J; Demirkan, Ayse; Döring, Angela; Gudnason, Vilmundur; Kiel, Douglas P; Kühnel, Brigitte; Mangino, Massimo; Mcknight, Barbara; Menni, Cristina; O'Connell, Jeffrey R; Oostra, Ben A; Shuldiner, Alan R; Song, Kijoung; Vandenput, Liesbeth; van Duijn, Cornelia M; Vollenweider, Peter; White, Charles C; Boehnke, Michael; Boettcher, Yvonne; Cooper, Richard S; Forouhi, Nita G; Gieger, Christian; Grallert, Harald; Hingorani, Aroon; Jørgensen, Torben; Jousilahti, Pekka; Kivimaki, Mika; Kumari, Meena; Laakso, Markku; Langenberg, Claudia; Linneberg, Allan; Luke, Amy; Mckenzie, Colin A; Palotie, Aarno; Pedersen, Oluf; Peters, Annette; Strauch, Konstantin; Tayo, Bamidele O; Wareham, Nicholas J; Bennett, David A; Bertram, Lars; Blangero, John; Blüher, Matthias; Bouchard, Claude; Campbell, Harry; Cho, Nam H; Cummings, Steven R; Czerwinski, Stefan A; Demuth, Ilja; Eckardt, Rahel; Eriksson, Johan G; Ferrucci, Luigi; Franco, Oscar H; Froguel, Philippe; Gansevoort, Ron T; Hansen, Torben; Harris, Tamara B; Hastie, Nicholas; Heliövaara, Markku; Hofman, Albert; Jordan, Joanne M; Jula, Antti; Kähönen, Mika; Kajantie, Eero; Knekt, Paul B; Koskinen, Seppo; Kovacs, Peter; Lehtimäki, Terho; Lind, Lars; Liu, Yongmei; Orwoll, Eric S; Osmond, Clive; Perola, Markus; Pérusse, Louis; Raitakari, Olli T; Rankinen, Tuomo; Rao, D C; Rice, Treva K; Rivadeneira, Fernando; Rudan, Igor; Salomaa, Veikko; Sørensen, Thorkild I A; Stumvoll, Michael; Tönjes, Anke; Towne, Bradford; Tranah, Gregory J; Tremblay, Angelo; Uitterlinden, André G; van der Harst, Pim; Vartiainen, Erkki; Viikari, Jorma S; Vitart, Veronique; Vohl, Marie-Claude; Völzke, Henry; Walker, Mark; Wallaschofski, Henri; Wild, Sarah; Wilson, James F; Yengo, Loïc; Bishop, D Timothy; Borecki, Ingrid B; Chambers, John C; Cupples, L Adrienne; Dehghan, Abbas; Deloukas, Panos; Fatemifar, Ghazaleh; Fox, Caroline; Furey, Terrence S; Franke, Lude; Han, Jiali; Hunter, David J; Karjalainen, Juha; Karpe, Fredrik; Kaplan, Robert C; Kooner, Jaspal S; McCarthy, Mark I; Murabito, Joanne M; Morris, Andrew P; Bishop, Julia A N; North, Kari E; Ohlsson, Claes; Ong, Ken K; Prokopenko, Inga; Richards, J Brent; Schadt, Eric E; Spector, Tim D; Widén, Elisabeth; Willer, Cristen J; Yang, Jian; Ingelsson, Erik; Mohlke, Karen L; Hirschhorn, Joel N; Pospisilik, John Andrew; Zillikens, M Carola; Lindgren, Cecilia; Kilpeläinen, Tuomas Oskari; Loos, Ruth J F

    2016-01-01

    To increase our understanding of the genetic basis of adiposity and its links to cardiometabolic disease risk, we conducted a genome-wide association meta-analysis of body fat percentage (BF%) in up to 100,716 individuals. Twelve loci reached genome-wide significance (P<5 × 10(-8)), of which eight w

  9. New loci for body fat percentage reveal link between adiposity and cardiometabolic disease risk

    NARCIS (Netherlands)

    Y. Lu (Yingchang); F.R. Day (Felix); S. Gustafsson (Stefan); M.L. Buchkovich (Martin); Na, J. (Jianbo); V. Bataille (Veronique); D.L. Cousminer (Diana); Z. Dastani (Zari); A. Drong (Alexander); T. Esko (Tõnu); D.M. Evans (David); M. Falchi (Mario); M.F. Feitosa (Mary Furlan); T. Ferreira (Teresa); A.K. Hedman (Asa); R. Haring (Robin); P.G. Hysi (Pirro); M.M. Iles (Mark M.); A.E. Justice (Anne); S. Kanoni (Stavroula); V. Lagou (Vasiliki); R. Li (Rui); X. Li (Xin); A. Locke (Adam); C. Lu (Chao); R. Mägi (Reedik); J.R.B. Perry (John); T.H. Pers (Tune); Q. Qi; Sanna, M. (Marianna); E.M. Schmidt (Ellen); W.R. Scott (William R.); D. Shungin (Dmitry); A. Teumer (Alexander); A.A.E. Vinkhuyzen (Anna A.); Walker, R.W. (Ryan W.); H.J. Westra (Harm-Jan); M. Zhang (Mingfeng); W. Zhang (Weihua); J.H. Zhao; Z. Zhu; U. Afzal (Uzma); T.S. Ahluwalia (Tarunveer Singh); S.J.L. Bakker (Stephan); C. Bellis (Claire); A. Bonnefond (Amélie); K. Borodulin (Katja); Buchman, A.S. (Aron S.); T. Cederholm (Tommy); A.C. Choh (Audrey); Choi, H.J. (Hyung Jin); J.E. Curran (Joanne); L.C.P.G.M. de Groot (Lisette); P.L. de Jager (Philip); R.A.M. Dhonukshe-Rutten (Rosalie); A.W. Enneman (Anke); E. Eury (Elodie); D.S. Evans (Daniel); T. Forsen (Tom); N. Friedrich (Nele); Fumeron, F. (Frédéric); M. Garcia (Melissa); Gärtner, S. (Simone); B.-G. Han; A.S. Havulinna (Aki); C. Hayward (Caroline); D.G. Hernandez (Dena); H.L. Hillege (Hans); T. Ittermann (Till); J.W. Kent (Jack W.); I. Kolcic (Ivana); T. Laatikainen (Tiina); J. Lahti (Jari); I.M. Leach (Irene Mateo); Lee, C.G. (Christine G.); J.-Y. Lee (Jong-Young); T. Liu (Tian); Liu, Y. (Youfang); S. Lobbens (Stéphane); Loh, M. (Marie); L.-P. Lyytikäinen (Leo-Pekka); Medina-Gomez, C. (Carolina); K. Michaëlsson; M.A. Nalls (Michael); C. Nielson (Carrie); L. Oozageer (Laticia); L. Pascoe (Laura); L. Paternoster (Lavinia); O. Polasek (Ozren); S. Ripatti (Samuli); M.A. Sarzynski (Mark A.); Shin, C.S. (Chan Soo); Naranäiä, N.S. (Nina Smolej); Spira, D. (Dominik); P. Srikanth (Priya); Steinhagen-Thiessen, E. (Elisabeth); Sung, Y.J. (Yun Ju); K.M.A. Swart (Karin); Taittonen, L. (Leena); T. Tanaka (Toshiko); E. Tikkanen (Emmi); N. van der Velde (Nathalie); N.M. van Schoor (Natasja); N. Verweij (Niek); A.F. Wright (Alan); L. Yu (Lei); J. Zmuda (Joseph); N. Eklund (Niina); T. Forrester (Terrence); N. Grarup (Niels); A.U. Jackson (Anne); K. Kristiansson (Kati); T. Kuulasmaa (Teemu); J. Kuusisto (Johanna); P. Lichtner (Peter); J. Luan (Jian'An); A. Mahajan (Anubha); S. Männistö (Satu); C. Palmer (Cameron); J.S. Ried (Janina); R.A. Scott (Robert); A. Stancáková (Alena); P.J. Wagner (Peter); A. Demirkan (Ayşe); A. Döring (Angela); V. Gudnason (Vilmundur); D.P. Kiel (Douglas P.); B. Kuhnel (Brigitte); M. Mangino (Massimo); B. McKnight (Barbara); C. Menni (Cristina); O'Connell, J.R. (Jeffrey R.); B.A. Oostra (Ben); A.R. Shuldiner (Alan); K. Song (Kijoung); L. Vandenput (Liesbeth); C.M. van Duijn (Cock); P. Vollenweider (Peter); C.C. White (Charles); M. Boehnke (Michael); Boettcher, Y. (Yvonne); Cooper, R.S. (Richard S.); N.G. Forouhi (Nita); C. Gieger (Christian); H. Grallert (Harald); A. Hingorani (Aroon); T. Jorgensen (Torben); P. Jousilahti (Pekka); M. Kivimaki (Mika); M. Kumari (Meena); M. Laakso (Markku); C. Langenberg (Claudia); A. Linneberg (Allan); Luke, A. (Amy); C.A. McKenzie (Colin); A. Palotie (Aarno); O. Pedersen (Oluf); A. Peters (Annette); K. Strauch (Konstantin); B. Tayo (Bamidele); N.J. Wareham (Nick); D.A. Bennett (David A.); L. Bertram (Lars); J. Blangero (John); M. Blüher (Matthias); C. Bouchard (Claude); H. Campbell (Harry); Cho, N.H. (Nam H.); S.R. Cummings (Steven R.); S.A. Czerwinski (Stefan); I. Demuth (Ilja); Eckardt, R. (Rahel); K. Hagen (Knut); L. Ferrucci (Luigi); O.H. Franco (Oscar); P. Froguel (Philippe); R.T. Gansevoort (Ron); T. Hansen (T.); T.B. Harris (Tamara); N. Hastie (Nick); M. Heliovaara (Markku); Hofman, A. (Albert); Jordan, J.M. (Joanne M.); A. Jula (Antti); M. Kähönen (Mika); E. Kajantie (Eero); P. Knekt; Koskinen, S. (Seppo); P. Kovacs (Peter); T. Lehtimäki (Terho); W.H.L. Kao (Wen); Y. Liu (Yongmei); E.S. Orwoll (Eric); C. Osmond (Clive); M. Perola (Markus); L. Perusse (Louis); Raitakari, O.T. (Olli T.); T. Rankinen (Tuomo); Rao, D.C.; Rice, T.K. (Treva K.); F. Rivadeneira Ramirez (Fernando); I. Rudan (Igor); V. Salomaa (Veikko); T.I.A. Sørensen (Thorkild); M. Stumvoll (Michael); A. Tönjes (Anke); B. Towne (Bradford); G.J. Tranah (Gregory); Tremblay, A. (Angelo); A.G. Uitterlinden (André); P. van der Harst (Pim); Vartiainen, E. (Erkki); J. Viikari (Jorma); Vitart, V. (Veronique); M.-C. Vohl (Marie-Claude); H. Völzke (Henry); Walker, M. (Mark); H. Wallaschofski (Henri); S.H. Wild (Sarah); J.F. Wilson (James F.); L. Yengo (Loic); D.T. Bishop (David Timothy); I.B. Borecki (Ingrid); J.C. Chambers (John C.); L.A. Cupples (Adrienne); A. Dehghan (Abbas); P. Deloukas (Panagiotis); Fatemifar, G. (Ghazaleh); C.S. Fox (Caroline); Furey, T.S. (Terrence S.); L. Franke (Lude); J. Han; D. Hunter (David); J. Karjalainen (Juha); F. Karpe (Fredrik); R.C. Kaplan (Robert); J.S. Kooner (Jaspal S.); M.I. McCarthy (Mark); J. Murabito (Joanne); A.P. Morris (Andrew); Bishop, J.A.N. (Julia A. N.); K.E. North (Kari); C. Ohlsson (Claes); K.K. Ong (Ken); I. Prokopenko (Inga); Richards, J.B. (J. Brent); E.E. Schadt (Eric); T.D. Spector (Timothy); E. Widen (Elisabeth); C.J. Willer (Cristen); J. Yang (Joanna); Ingelsson, E. (Erik); K.L. Mohlke (Karen); J.N. Hirschhorn (Joel); J.A. Pospisilik (Andrew); M.C. Zillikens (Carola); C.M. Lindgren (Cecilia M.); T.O. Kilpeläinen (Tuomas); R.J.F. Loos (Ruth)

    2016-01-01

    textabstractTo increase our understanding of the genetic basis of adiposity and its links to cardiometabolic disease risk, we conducted a genome-wide association meta-analysis of body fat percentage (BF%) in up to 100,716 individuals. Twelve loci reached genome-wide significance (Po5108), of which e

  10. New loci for body fat percentage reveal link between adiposity and cardiometabolic disease risk

    DEFF Research Database (Denmark)

    Lu, Yingchang; Day, Felix R; Gustafsson, Stefan

    2016-01-01

    To increase our understanding of the genetic basis of adiposity and its links to cardiometabolic disease risk, we conducted a genome-wide association meta-analysis of body fat percentage (BF%) in up to 100,716 individuals. Twelve loci reached genome-wide significance (P<5 × 10(-8)), of which eigh...

  11. Brief Report: On the Concordance Percentages for Autistic Spectrum Disorder of Twins

    Science.gov (United States)

    Bohm, Henry V.; Stewart, Melbourne G.

    2009-01-01

    In the development of genetic theories of Autistic Spectrum Disorder (ASD) various characteristics of monozygotic (MZ) and dizygotic (DZ) twins are often considered. This paper sets forth a possible refinement in the interpretation of the MZ twin concordance percentages for ASD underlying such genetic theories, and, drawing the consequences from…

  12. The percentage of bacterial genes on leading versus lagging strands is influenced by multiple balancing forces

    Science.gov (United States)

    Mao, Xizeng; Zhang, Han; Yin, Yanbin; Xu, Ying

    2012-01-01

    The majority of bacterial genes are located on the leading strand, and the percentage of such genes has a large variation across different bacteria. Although some explanations have been proposed, these are at most partial explanations as they cover only small percentages of the genes and do not even consider the ones biased toward the lagging strand. We have carried out a computational study on 725 bacterial genomes, aiming to elucidate other factors that may have influenced the strand location of genes in a bacterium. Our analyses suggest that (i) genes of some functional categories such as ribosome have higher preferences to be on the leading strands; (ii) genes of some functional categories such as transcription factor have higher preferences on the lagging strands; (iii) there is a balancing force that tends to keep genes from all moving to the leading and more efficient strand and (iv) the percentage of leading-strand genes in an bacterium can be accurately explained based on the numbers of genes in the functional categories outlined in (i) and (ii), genome size and gene density, indicating that these numbers implicitly contain the information about the percentage of genes on the leading versus lagging strand in a genome. PMID:22735706

  13. Use of enzymes in diets with different percentages of added fat for broilers

    Directory of Open Access Journals (Sweden)

    F.G.P. Costa

    2013-06-01

    Full Text Available We assessed the extent to which the removal of fat source, and consequently its compounds, such as linoleic acid, can affect the performance of broilers. We used 600 male Cobb 500 day old chicks. The birds were distributed in a completely randomized experimental design, with five treatments and six replicates of 20 birds each. The treatments were: (T1 diet - positive control (PC, which met the nutritional needs; (T2 diet - negative control (CN, a reduction of 100kcal/kg and low linoleic acid content; (T3: diet - negative control reformulated for low linoleic acid content and a set of Quantum phytase XT and Econase XT 25 (BAL + QFit-Eco, (T4: diet - negative control reformulated, with the percentage of linoleic acid adjusted to an intermediate value between the value of the diet and diet CP and CN to use a set of Quantum phytase XT and XT Econase 25 (IAL + QFit-Eco and (T5: diet - negative control reformulated, with the percentage of linoleic acid adjusted to a value similar to that of the positive control diet and joint use of Quantum phytase XT and XT Econase 25 (AAL + QFit-Eco. The joint use of Quantum Phytase and Econase promoted improvement in the performance of broilers from 1 to 21 days. The greatest weight gain was obtained with diets containing percentages of total fat and linoleic acids. Dietary supplementation with enzymes resulted in higher levels of calcium in the tibia, whatever the percentage of linoleic studied.

  14. New loci for body fat percentage reveal link between adiposity and cardiometabolic disease risk

    NARCIS (Netherlands)

    Lu, Y.; Groot, de C.P.G.M.; Dhonukshe-Rutten, R.A.M.

    2016-01-01

    To increase our understanding of the genetic basis of adiposity and its links to cardiometabolic disease risk, we conducted a genome-wide association meta-analysis of body fat percentage (BF%) in up to 100,716 individuals. Twelve loci reached genome-wide significance (P<5 × 10−8), of which eight

  15. Influence of tinnitus percentage index of speech recognition in patients with normal hearing

    Directory of Open Access Journals (Sweden)

    Urnau, Daila

    2010-12-01

    Full Text Available Introduction: The understanding of speech is one of the most important measurable aspects of human auditory function. Tinnitus affects the quality of life, impairing communication. Objective: To investigate possible changes in the Percentage Index of Speech Recognition (SDT in individuals with tinnitus have normal hearing and examining the relationship between tinnitus, gender and age. Methods:A retrospective study by analyzing the records of 82 individuals of both genders, aged 21-70 years, totaling 128 ears with normal hearing. The ears were analyzed separately, and divided into control group, no complaints of tinnitus and group study, with complaints of tinnitus. The variables gender and age groups and examined the influence of tinnitus in the SDT. It was considered normal, the percentage of 100% correct and changed, and the value between 88-96%. These criteria were adopted, since the percentage below 88% correct is found in individuals with sensorineural hearing loss. Results:There was no statistically significant difference between the variables age and tinnitus, and tinnitus SDT, only gender and tinnitus. The prevalence of tinnitus in females (56%, higher incidence of tinnitus in the age group 31-40 years (41.67% and fewer from 41 to 50 years (18.75% and on the SDT there was a greater percentage change in individuals with tinnitus (61.11%. Conclusion: The buzz does not interfere with SDT and there is no relationship between tinnitus and age, only between tinnitus and gender.

  16. Government Expenditures on Education as the Percentage of GDP in the EU

    Science.gov (United States)

    Galetic, Fran

    2015-01-01

    This paper analyzes the government expenditures as the percentage of gross domestic product across countries of the European Union. There is a statistical model based on Z-score, whose aim is to calculate how much each EU country deviates from the average value. The model shows that government expenditures on education vary significantly between…

  17. Detection of erythropoietin misuse by the Athlete Biological Passport combined with reticulocyte percentage

    DEFF Research Database (Denmark)

    Bejder, Jacob; Aachmann-Andersen, Niels Jacob; Bonne, Thomas Christian

    2016-01-01

    The sensitivity of the adaptive model of the Athlete Biological Passport (ABP) and reticulocyte percentage (ret%) in detection of recombinant human erythropoietin (rHuEPO) misuse was evaluated using both a long-term normal dose and a brief high dose treatment regime. Sixteen subjects received...

  18. New loci for body fat percentage reveal link between adiposity and cardiometabolic disease risk

    DEFF Research Database (Denmark)

    Lu, Yingchang; Day, Felix R; Gustafsson, Stefan

    2016-01-01

    To increase our understanding of the genetic basis of adiposity and its links to cardiometabolic disease risk, we conducted a genome-wide association meta-analysis of body fat percentage (BF%) in up to 100,716 individuals. Twelve loci reached genome-wide significance (P<5 × 10(-8)), of which eigh...

  19. Annual Percentage Rate and Annual Effective Rate: Resolving Confusion in Intermediate Accounting Textbooks

    Science.gov (United States)

    Vicknair, David; Wright, Jeffrey

    2015-01-01

    Evidence of confusion in intermediate accounting textbooks regarding the annual percentage rate (APR) and annual effective rate (AER) is presented. The APR and AER are briefly discussed in the context of a note payable and correct formulas for computing each is provided. Representative examples of the types of confusion that we found is presented…

  20. Ionospheric Modification by High Power, Obliquely Propagated HF Radio Wave Transmissions. Part 1. Experimental

    Science.gov (United States)

    1993-07-01

    frequency of the disturbing transmitter is greater than the i.. asma frequency in the ionospheric interaction region. In fact, with many practical radio...NY) lay in the Gulf of Mexico and it was not possible to use an oblique probe system similar to- the technique used by the Soviets in their...using a vertical incidence sounder at Albuquerque, New Mexico (35.11N, 106.8 0W) at the midpoint of the 2400 km path. This technique insures that the

  1. Studies of Plasma Instability Processes Excited by Ground Based High Power HF ("Heating") Facilities

    Science.gov (United States)

    2001-04-01

    and Megill, 1974; Carlson, 1974; Bernhardt et al., 1989). During the last years new interesting results have been obtained at HAARP facility (Peterson...Haslett and Megill, 1974; Carlson, 1974; Bernhardt et al., 1989). During the last years new interesting results have been obtained at HAARP facility

  2. Morning sector drift-bounce resonance driven ULF waves observed in artificially-induced HF radar backscatter

    Directory of Open Access Journals (Sweden)

    L. J. Baddeley

    Full Text Available HF radar backscatter, which has been artificially-induced by a high power RF facility such as the EISCAT heater at Tromsø, has provided coherent radar ionospheric electric field data of unprecedented temporal resolution and accuracy. Here such data are used to investigate ULF wave processes observed by both the CUTLASS HF radars and the EISCAT UHF radar. Data from the SP-UK-OUCH experiment have revealed small-scale (high azimuthal wave number, m -45 waves, predominantly in the morning sector, thought to be brought about by the drift-bounce resonance processes. Conjugate observations from the Polar CAM-MICE instrument indicate the presence of a non-Maxwellian ion distribution function. Further statistical analysis has been undertaken, using the Polar TIMAS instrument, to reveal the prevalence and magnitude of the non-Maxwellian energetic particle populations thought to be responsible for generating these wave types.

    Key words. Ionosphere (active experiments; wave-particle interactions Magnetospheric physics (MHD waves and instabilities

  3. Nano-indentation of ion-beam modified HfN/Si system: Identification of the amorphized inter-layer

    Energy Technology Data Exchange (ETDEWEB)

    Nowak, R. E-mail: nowak@ohm.mec.hiroshima-u.ac.jp; Li, C.L.; Okada, T.; Yoshida, F

    1999-01-02

    The work aims to clarify the considerable softening registered for the HfN/Si system after its bombardment with energetic ions (E=1, 2.5 and 5 MeV, fluence=10{sup 14} Au{sup ++}cm{sup -2}). The mechanical properties of the virgin and ion-modified films were characterized using the depth-sensing indentation experiments performed under maximum indentation load ranging from 2 to 50 mN. The surface deformation in the vicinity of the contact with a triangular indenter was modeled by the finite element simulation of the axisymmetric-indenter penetration into the hard-film/soft-substrate system. The applied approach allowed us to attribute the observed difference in hardness of virgin and ion-treated samples to the structural changes which have been induced in the silicon substrate by bombarding ions. The calculated results led us to the conclusion that bombardment with energetic Au-ions resulted in formation of the inter-layer of amorphous silicon, right under HfN film. The present work aims to prove that the depth-sensing experiments supplemented by the finite-element calculations provide a new, powerful method of characterizing the multilayer structures.

  4. Cluster observations of ELF/VLF signals generated by modulated heating of the lower ionosphere with the HAARP HF transmitter

    Directory of Open Access Journals (Sweden)

    M. Platino

    2004-07-01

    Full Text Available It is now well known that amplitude modulated HF transmissions into the ionosphere can be used to generate ELF/VLF signals using the so-called "electrojet antenna". Although most observations of the generated ELF/VLF signals have been made on the ground, several low and high-altitude satellite observations have also been reported (James et al., 1990. One of the important unknowns in the physics of ELF/VLF wave generation by ionospheric heating is the volume of the magnetosphere illuminated by the ELF/VLF waves. In an attempt to investigate this question further, ground-satellite conjunction experiments have recently been conducted using the four Cluster satellites and the HF heater of the High-Frequency Active Auroral Research Program (HAARP facility in Gakona, Alaska. Being located on largely closed field lines at L≈4.9, HAARP is currently also being used for ground-to-ground type of ELF/VLF wave-injection experiments, and will be increasingly used for this purpose as it is now being upgraded for higher power operation. In this paper, we describe the HAARP installation and present recent results of the HAARP-Cluster experiments. We give an overview of the detected ELF/VLF signals at Cluster, and a possible explanation of the spectral signature detected, as well as the determination of the location of the point of injection of the HAARP ELF/VLF signals into the magnetosphere using ray tracing.

  5. Synthesis of bulk FeHfBO soft magnetic materials and its loss characterization at megahertz frequency

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Yang; Kou Xiaoming; Warsi Muhammad, Asif; Lin Shuo; Harris, Brendan S.; Parsons, Paul E.; Xiao, John Q. [Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716 (United States); Mu Mingkai; Lee, Fred C. [Center for Power Electronics System, Virginia Polytechnic and State University, Blacksburg, Virginia 24060 (United States); Zhu Hao [Spectrum Magnetics LLC, Wilmington, Delaware 19804 (United States)

    2013-05-07

    Magnetic core materials with low loss, high saturation magnetization, large permeability, and operating frequency above 1 MHz are in high demands for the next generation of miniaturized power electronics. Amorphous FeHfB ribbons with thickness around 20 {mu}m have been fabricated through melt-spinning. Different heat treatments were performed on the FeHfB ribbons, and the relations among heat treatments, microstructure, and magnetic properties have been explored. Properties such as coercivity (H{sub c}) of 2.0 Oe and saturation magnetic flux density (B{sub S}) of 1.2 T have been achieved in samples with exchange coupling. The losses can be minimized by balancing the hysteretic and eddy current losses and can be further reduced with additional magnetic field annealing. At 5 MHz with peak magnetic flux density of 20 mT, the materials show core losses comparable to the best ferrites, but with higher permeability value of about 200 and superior saturation induction of more than 1 T.

  6. Percentage tumor necrosis following chemotherapy in neuroblastoma correlates with MYCN status but not survival.

    Science.gov (United States)

    Bomken, Simon; Davies, Beverley; Chong, Leeai; Cole, Michael; Wood, Katrina M; McDermott, Michael; Tweddle, Deborah A

    2011-03-01

    The percentage of chemotherapy-induced necrosis in primary tumors corresponds with outcome in several childhood malignancies, including high-risk metastatic diseases. In this retrospective pilot study, the authors assessed the importance of postchemotherapy necrosis in high-risk neuroblastoma with a histological and case notes review of surgically resected specimens. The authors reviewed all available histology of 31 high-risk neuroblastoma cases treated with COJEC (dose intensive etoposide and vincristine with either cyclophosphamide, cisplatin or carboplatin) or OPEC/OJEC (etoposide, vincristine and cyclophosphamide with alternating cisplatin [OPEC] or carboplatin [OJEC]) induction chemotherapy in 2 Children's Cancer & Leukaemia Group (CCLG) pediatric oncology centers. The percentage of postchemotherapy necrosis was assessed and compared with MYCN amplification status and overall survival. The median percentage of postchemotherapy tumor necrosis was 60%. MYCN status was available for 28 cases, of which 12 were amplified (43%). Survival in cases with ≥ 60% necrosis or ≥ 90% necrosis was not better than those with less necrosis, nor was percentage necrosis associated with survival using Cox regression. However, MYCN-amplified tumors showed a higher percentage of necrosis than non-MYCN-amplified tumors, 71.3% versus 37.2% (P = .006). This effect was not related to prechemotherapy necrosis and did not confer improved overall survival. Postchemotherapy tumor necrosis is higher in patients with MYCN amplification. In this study, postchemotherapy necrosis did not correlate with overall survival and should not lead to modification of postoperative treatment. However, these findings need to be confirmed in a larger prospective study of children with high-risk neuroblastoma.

  7. Android and gynoid fat percentages and serum lipid levels in United States adults.

    Science.gov (United States)

    Min, Kyoung-Bok; Min, Jin-Young

    2015-03-01

    Accumulating evidence suggests that fat distribution is a better predictor of cardiovascular disease than body mass index (BMI). The aim of this study was to investigate the association of android and gynoid fat percentages with lipid profiles to determine whether android and/or gynoid fat percentages are associated with serum lipid levels. A population-based cross-sectional study. Five thousand six hundred and ninety-six adults (20 years and older) who participated in the National Health and Nutrition Examination Survey 2003-2006. The regional body composition in the android and gynoid regions was defined by dual energy X-ray absorptiometry (DXA). The estimation of lipid risk profiles included total cholesterol, high-density lipoprotein (HDL) -cholesterol, low-density lipoprotein (LDL) -cholesterol and triglycerides (TG). Regardless of gender, android and gynoid body fat percentages were positively and significantly correlated with BMI and waist circumference. After adjustment for age, ethnicity, education, smoking, alcohol consumption, dyslipidaemia and BMI, increases in android fat percentage were significantly associated with total cholesterol, TG and HDL cholesterol in males, and total cholesterol, HDL cholesterol and LDL cholesterol in females. The gynoid fat percentages showed a positive correlation with total cholesterol in males, whereas gynoid fat accumulation in females showed a favourable association with TG and HDL cholesterol. The observed associations differed according to ethnic groups. Our results suggest that regional fat distribution in the android and gynoid regions have different effects on lipid profiles, and that fat in the android region, rather than the gynoid region, may be an important factor in determining the risk of cardiovascular disease. © 2014 John Wiley & Sons Ltd.

  8. Archean Lithosphere Beneath Arctic Canada: Lu-Hf Isotope Systematics for Kimberlite-Hosted Garnet-Peridotites From Somerset Island

    Science.gov (United States)

    Schmidberger, S. S.; Simonetti, A.; Francis, D.; Gariepy, C.

    2001-05-01

    Knowledge of the age of lithospheric mantle underlying the continents provides valuable constraints for the timing of formation and stabilization of Archean cratons. This study reports Lu-Hf isotopic data for garnet-peridotites, and their constituent garnets, from the Nikos kimberlite (100 Ma) on Somerset Island in the Canadian Arctic obtained using a Micromass IsoProbe multicollector inductively coupled plasma mass spectrometer (MC-ICP-MS) at GEOTOP-UQAM. The low temperature peridotites (1100 C; 160-190 km) and their 176Hf/177Hf(0.1Ga) isotopic compositions (0.28265-0.28333; \\epsilonHf(0.1Ga)=-2 to +22) are less radiogenic than those of the shallow xenoliths. A Lu-Hf isochron for six peridotites yields a mid Archean age of 3.4\\pm0.3 Ga and an initial 176Hf/177Hf ratio of 0.28101\\pm24. The remaining peridotites (n=9), in contrast, are characterized by extremely high (+35) initial \\epsilonHf(3.4Ga) values, which correlate negatively with their 176Lu/177Hf ratios, suggesting addition of Hf as a result of metasomatic interaction with the host kimberlite. The garnets from the low temperature (3.4 Ga old) peridotites are characterized by high 176Lu/177Hf ratios and define an errorchron age of 1.4\\pm0.2 Ga, which may reflect re-equilibration of Hf during kimberlite magmatism.

  9. Design for human factors (DfHF): a grounded theory for integrating human factors into production design processes.

    Science.gov (United States)

    Village, Judy; Searcy, Cory; Salustri, Filipo; Patrick Neumann, W

    2015-01-01

    The 'design for human factors' grounded theory explains 'how' human factors (HF) went from a reactive, after-injury programme in safety, to being proactively integrated into each step of the production design process. In this longitudinal case study collaboration with engineers and HF Specialists in a large electronics manufacturer, qualitative data (e.g. meetings, interviews, observations and reflections) were analysed using a grounded theory methodology. The central tenet in the theory is that when HF Specialists acclimated to the engineering process, language and tools, and strategically aligned HF to the design and business goals of the organisation, HF became a means to improve business performance. This led to engineers 'pulling' HF Specialists onto their team. HF targets were adopted into engineering tools to communicate HF concerns quantitatively, drive continuous improvement, visibly demonstrate change and lead to benchmarking. Senior management held engineers accountable for HF as a key performance indicator, thus integrating HF into the production design process. Practitioner Summary: Research and practice lack explanations about how HF can be integrated early in design of production systems. This three-year case study and the theory derived demonstrate how ergonomists changed their focus to align with design and business goals to integrate HF into the design process.

  10. A multistatic HF beacon network for ionospheric specification in the Peruvian sector

    Science.gov (United States)

    Hysell, D. L.; Milla, M. A.; Vierinen, J.

    2016-05-01

    A small network of HF beacon transmitters and receivers has been deployed in Peru for specifying the F region ionosphere in the sector. The effort is motivated by ionospheric disturbances associated with equatorial spread F (ESF) and specifically disturbances arising under inauspicious conditions for ESF as determined by numerical simulations. The beacons operate at dual frequencies (2.72 and 3.64 MHz). They are CW but incorporate pseudorandom noise (PRN) coding so that the group delays of the links can be measured. Other observables are power, Doppler shift, bearing, and polarization. A transmitter is currently deployed at Ancon (11°46'37''S, 77°09'1''W, 51 m above sea level (asl)), while receivers are at Jicamarca (11°57'5.8''S, 76°52'27''W, 510 m asl) and Huancayo (12°02'30''S, 75°19'15''W, 3315 m asl). An algorithm for inverting the beacon data combined with electron density profiles from Jicamarca is described. Data and representative solutions from an experimental campaign held in August 2015 are presented and evaluated.

  11. Physical Layer Definition for a Long-Haul HF Antarctica to Spain Radio Link

    Directory of Open Access Journals (Sweden)

    Rosa Ma Alsina-Pagès

    2016-05-01

    Full Text Available La Salle and the Observatori de l’Ebre (OE have been involved in a remote sensing project in Antarctica for the last 11 years. The OE has been monitoring the geomagnetic activity for more than twenty years and also the ionospheric activity of the last ten years in the Spanish Antarctic Station Juan Carlos I (ASJI (62.7 ° S, 299.6 ° E. La Salle is finishing the design and testing of a low-power communication system between the ASJI and Cambrils (41.0 ° N, 1.0 ° E with a double goal: (i the transmission of data from the sensors located at the ASJI and (ii the performance of an oblique ionospheric sounding of a 12,760 km HF link. Previously, La Salle has already performed sounding and modulation tests to describe the channel performance in terms of availability, Signal-to-Noise Ratio (SNR, Doppler spread and delay spread. This paper closes the design of the physical layer, by means of the channel error study and the synchronization performance, and concludes with a new physical layer proposal for the Oblique Ionosphere Sounder. Narrowband and wideband frames have been defined to be used when the oblique sounder performs as an ionospheric sensor. Finally, two transmission modes have been defined for the modem performance: the High Robustness Mode (HRM for low SNR hours and the High Throughput Mode (HTM for the high SNR hours.

  12. Novel monitoring method for the management of heart failure: combined measurement of body weight and bioimpedance index of body fat percentage.

    Science.gov (United States)

    Kataoka, Hajime

    2009-11-01

    Although body weight scales are most commonly used to evaluate body fluid status during follow-up of definite heart failure (HF) patients, bioimpedance measurement methods have become increasingly available in the clinical setting. These monitoring methods, however, are typically used separately to evaluate body fluid status in HF patients. Kataoka developed a novel method for monitoring HF patients using a digital weight scale that incorporated a bioelectrical impedance analyzer. This method combines the well-known advantages of body weighing with a refined bioimpedance technique to monitor HF status and provides valid information regarding a change in a patient's body fluid status during follow-up for HF, such as predominant fluid versus fat weight gain or loss. This special report describes examples of the practical use of this method for monitoring and treating definite HF patients.

  13. External perforated Solar Screens for daylighting in residential desert buildings: Identification of minimum perforation percentages

    KAUST Repository

    Sherif, Ahmed

    2012-06-01

    The desert climate is endowed by clear sky conditions, providing an excellent opportunity for optimum utilization of natural light in daylighting building indoor spaces. However, the sunny conditions of the desert skies, in countries like Egypt and Saudi Arabia, result in the admittance of direct solar radiation, which leads to thermal discomfort and the incidence of undesired glare. One type of shading systems that is used to permit daylight while controlling solar penetration is " Solar Screens" Very little research work addressed different design aspects of external Solar Screens and their influence on daylighting performance, especially in desert conditions, although these screens proved their effectiveness in controlling solar radiation in traditional buildings throughout history.This paper reports on the outcomes of an investigation that studied the influence of perforation percentage of Solar Screens on daylighting performance in a typical residential living room of a building in a desert location. The objective was to identify minimum perforation percentage of screen openings that provides adequate illuminance levels in design-specific cases and all-year-round.Research work was divided into three stages. Stage one focused on the analysis of daylighting illuminance levels in specific dates and times, while the second stage was built on the results of the first stage, and addressed year round performance using Dynamic Daylight Performance Metrics (DDPMs). The third stage addressed the possibility of incidence of glare in specific cases where illuminance levels where found very high in some specific points during the analysis of first stage. The research examined the daylighting performance in an indoor space with a number of assumed fixed experimentation parameters that were chosen to represent the principal features of a typical residential living room located in a desert environment setting.Stage one experiments demonstrated that the screens fulfilled the

  14. Photocurrent generation in carbon nanotube/cubic-phase HfO2 nanoparticle hybrid nanocomposites

    Directory of Open Access Journals (Sweden)

    Protima Rauwel

    2016-07-01

    Full Text Available A hybrid material consisting of nonfunctionalized multiwall carbon nanotubes (MWCNTs and cubic-phase HfO2 nanoparticles (NPs with an average diameter of 2.6 nm has been synthesized. Free standing HfO2 NPs present unusual optical properties and a strong photoluminescence emission in the visible region, originating from surface defects. Transmission electron microscopy studies show that these NPs decorate the MWCNTs on topological defect sites. The electronic structure of the C K-edge in the nanocomposites was probed by electron energy loss spectroscopy, highlighting the key role of the MWCNT growth defects in anchoring HfO2 NPs. A combined optical emission and absorption spectroscopy approach illustrated that, in contrast to HfO2 NPs, the metallic MWCNTs do not emit light but instead expose their discrete electronic structure in the absorption spectra. The hybrid material manifests characteristic absorption features with a gradual merger of the MWCNT π-plasmon resonance band with the intrinsic defect band and fundamental edge of HfO2. The photoluminescence of the nanocomposites indicates features attributed to combined effects of charge desaturation of HfO2 surface states and charge transfer to the MWCNTs with an overall reduction of radiative recombination. Finally, photocurrent generation under UV–vis illumination suggests that a HfO2 NP/MWCNT hybrid system can be used as a flexible nanodevice for light harvesting applications.

  15. Superelasticity and Shape Memory Behavior of NiTiHf Alloys

    Science.gov (United States)

    Sehitoglu, H.; Wu, Y.; Patriarca, L.; Li, G.; Ojha, A.; Zhang, S.; Chumlyakov, Y.; Nishida, M.

    2017-06-01

    The NiTiHf high-temperature shape memory alloys represent a significant advancement in extending the functionality of binary NiTi to elevated temperatures above 100 °C. Despite this potential, the previous results in the literature point to a disappointingly low shape memory strains with addition of Hf. On the other hand, based on theoretical analysis using the lattice constants, the transformation strains should increase substantially with increase in Hf content. The present paper addresses this discrepancy, and using atomistic simulations, determination of twinning modes in martensite with transmission electron microscopy, digital image measurements of habit plane orientation, and strains in single-crystal specimens show that the experimental transformation strains in NiTiHf indeed increase with increasing Hf to unprecedented strain levels near 20%. The Hf contents considered were in the range 6.25-25 at.%, and NiTi (0% Hf) results are provided as the baseline. The current work represents more than 60 experiments representing an extremely thorough study on single crystals and polycrystals.

  16. Isolation and Characterization of a Virulent Bacteriophage φPA-HF17 of Pseudomonas aeruginosa

    Directory of Open Access Journals (Sweden)

    Fang Han

    2014-09-01

    Full Text Available Pseudomonas aeruginosa, an important causative agent of nosocomial infection, is found throughout the hospital environment in moist reservoirs, and multidrug-resistant strains of P. aeruginosa have been increasingly reported worldwide. Bacteriophages are often considered potential therapeutic candidates in treating infectious diseases. In this study, a novel virulent bacteriophage φPA-HF17, specific infecting clinical isolates of P. aeruginosa, was isolated and characterized from environmental sewage. Transmission electron microscopy showed that phage φPA-HF17 had an icosahedral head with a very short tail, and exhibited characteristics typical of a podovirus. Restriction analysis indicated that phage φPA-HF17 was a double-stranded DNA virus, which might be digested by some restriction endonucleases. Phage φPA-HF17 was highly infectious with a rapid adsorption (>90% adsorbed in 4 min. In a one-step growth experiment, phage φPA-HF17 was shown having a latent period of 10 minute, with corresponding burst sizes of 200 PFU/cell. Furthermore, when φPA-HF17 alone was incubated at different pHs and different temperatures, the phage was stable over a wide pH range (4 to 10 and at extreme temperature (50°C. These results suggest that φPA-HF17 may be candidate therapeutic phage to control P. aeruginosa infection.

  17. In-situ atomic layer deposition growth of Hf-oxide

    Energy Technology Data Exchange (ETDEWEB)

    Karavaev, Konstantin

    2010-06-17

    We have grown HfO{sub 2} on Si(001) by atomic layer deposition (ALD) using HfCl{sub 4}, TEMAHf, TDMAHf and H{sub 2}O as precursors. The early stages of the ALD were investigated with high-resolution photoelectron spectroscopy and X-ray absorption spectroscopy. We observed the changes occurring in the Si 2p, O 1s, Hf 4f, Hf 4d, and Cl 2p (for HfCl{sub 4} experiment) core level lines after each ALD cycle up to the complete formation of two layers of HfO{sub 2}. The investigation was carried out in situ giving the possibility to determine the properties of the grown film after every ALD cycle or even after a half cycle. This work focused on the advantages in-situ approach in comparison with ex-situ experiments. The study provides to follow the evolution of the important properties of HfO{sub 2}: contamination level, density and stoichiometry, and influence of the experimental parameters to the interface layer formation during ALD. Our investigation shows that in-situ XPS approach for ALD gives much more information than ex-situ experiments. (orig.)

  18. Linear Trimeric Hafnium Clusters in Hf0.86(1I3

    Directory of Open Access Journals (Sweden)

    Jan Beekhuizen

    2011-05-01

    Full Text Available The reduction of hafnium tetraiodide, HfI4, with aluminum at 600 °C or 850 °C in the presence of a NaI flux resulted in black single crystals of Hf0.86(1I3. This composition corresponds well to the upper end of the non-stoichiometry range 0.89 ≤ x ≤ 1.00 previously reported for HfxI3. The crystal structure (a = 1250.3(2, c = 1999.6(3 pm, R-3m, Z = 18 is made up of hexagonal closest packed layers of iodide ions. One third of the octahedral holes would be filled as in TiI3 or ZrI3 if it were Hf1.00I3. In Hf0.86(1I3, one out of six octahedral holes along [001] are, however, only occupied by 16%. In contrast to TiI3-I and ZrI3, one striking structural feature is in the formation of linear hafnium trimers with identical Hf―Hf distances of 318.3(2 pm rather than the formation of dimers. These may be associated with Hf―Hf bonding although only 2.64 electrons are available for one Hf5.16I18 column.

  19. Microstructure and Phase Stability of Single Crystal NiAl Alloyed with Hf and Zr

    Science.gov (United States)

    Locci, I. E.; Dickerson, R. M.; Garg, A.; Noebe, R. D.; Whittenberger, J. D.; Nathal, M. V.; Darolia, R.

    1996-01-01

    Six near stoichiometric, NiAl single-crystal alloys, with 0.05-1.5 at.% of Hf and Zr additions plus Si impurities, were microstructurally analyzed in the as-cast, homogenized, and aged conditions. Hafnium-rich interdendritic regions, containing the Heusler phase (Ni2AlHf), were found in all the as-cast alloys containing Hf. Homogenization heat treatments partially reduced these interdendritic segregated regions. Transmission electron microscopy (TEM) observations of the as-cast and homogenized microstructures revealed the presence of a high density of fine Hf (or Zr) and Si-rich precipitates. These were identified as G-phase, Nil6X6Si7, or as an orthorhombic NiXSi phase, where X is Hf or Zr. Under these conditions the expected Heusler phase (beta') was almost completely absent. The Si responsible for the formation of the G and NiHfSi phases is the result of molten metal reacting with the Si-containing crucible used during the casting process. Varying the cooling rates after homogenization resulted in the refinement or complete suppression of the G and NiHfSi phases. In some of the alloys studied, long-term aging heat treatments resulted in the formation of Heusler precipitates, which were more stable at the aging temperature and coarsened at the expense of the G-phase. In other alloys, long-term aging resulted in the formation of the NiXSi phase. The stability of the Heusler or NiXSi phases can be traced to the reactive element (Hf or Zr) to silicon ratio. If the ratio is high, then the Heusler phase appears stable after long time aging. If the ratio is low, then the NiHfSi phase appears to be the stable phase.

  20. Vibrational relaxation of hydrogen fluoride by HF dimers in a laser excited nozzle beam

    Energy Technology Data Exchange (ETDEWEB)

    Knuth, E.L.; Rubahn, H.; Toennies, J.P.; Wanner, J.

    1986-09-01

    An HF nozzle beam and a cw HF laser beam in a coaxial and antiparallel arrangement facilitated exciting HF molecules vibrationally in v-italic = 1,J-italic up to the saturation limit. A beam consisting exclusively of monomeric HF was generated by heating the beam source to 600 K and was confirmed using a mass spectrometer. Energy-flux measurements made using a bolometer indicate that the vibrational energy distribution initiated by the laser is conserved, confirming that V--T energy transfer to monomers is slow. The maximum measured flux of HF(v-italic = 1,J-italic) molecules was 1.5 x 10/sup 17/ molecules s/sup -1/ sr/sup -1/ at 670 mbar stagnation pressure. Beams consisting of a mixture of monomeric and polymeric HF were generated using appropriate combinations of source temperature and pressure. In the presence of dimers, the excited monomers relax rapidly by a fast V--V transfer and subsequent predissociation of the metastable dimers. The loss of beam energy due to energy transport by the departing dimer fragments was detected bolometrically. The laser-induced depletion of dimers was determined over a wide source pressure range at T-italic/sub 0/ = 300 K using a mass spectrometer. From a kinetic model of these dimer-depletion data, the product of cross section and transfer probability for V--V energy transfer from HF (v-italic = 1) monomers to dimers was deduced to be 14 A-circle/sup 2/. The terminal-dimer-concentration equation for HF nozzle beams was refined. An analysis of the energy fluxes measured by the bolometer with no laser excitation of the beam revealed that, for an HF nozzle beam, the flow from the source to the detector is, in general, nonisenthalpic due to the onset of dimerization. Mach-number focusing enriches the dimer mole fractions detected by the bolometer.

  1. Properties of HfAlO film deposited by plasma enhanced atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Duo [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Changning Road 865, Shanghai 200050 (China); Cheng, Xinhong, E-mail: xh_cheng@mail.sim.ac.cn [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Changning Road 865, Shanghai 200050 (China); Jia, Tingting; Zheng, Li; Xu, Dawei; Wang, Zhongjian; Xia, Chao; Yu, Yuehui [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Changning Road 865, Shanghai 200050 (China)

    2013-07-15

    Plasma enhanced atomic layer deposition (PEALD) method can reduce film growing temperature, and allow in situ plasma treatment. In this work, HfAlO and HfO{sub 2} films were deposited with PEALD at 160 °C. Microstructure analysis showed that both films were amorphous after rapid thermal annealing (RTA) treatment, and HfAlO sample showed better interfacial structure than HfO{sub 2}. X-ray photoelectron spectroscopy (XPS) spectra indicated that main component of the interfacial layer of HfAlO sample was Hf–Si–O and Al–Si–O bonds, the valence band offset value between the HfAlO film and Si substrate was calculated to be 2.5 eV. The dominant leakage current mechanism of the samples was Schottky emission at a low electric field (<1.4 MV/cm), and Poole–Frenkel emission mechanism at a higher electric field (>1.4 MV/cm). The equivalent oxide thicknesses (EOT) of the HfAlO samples were 1.0 nm and 1.3 nm, respectively. The density of interface states between dielectric and substrate were calculated to be 1.2 × 10{sup 12} eV{sup −1}cm{sup −2} and 1.3 × 10{sup 12} eV{sup −1}cm{sup −2}, respectively. In comparison with HfO{sub 2} film, HfAlO film has good interfacial structure and electrical performance.

  2. HF-induced airglow structure as a proxy for ionospheric irregularity detection

    Science.gov (United States)

    Kendall, E. A.

    2013-12-01

    The High Frequency Active Auroral Research Program (HAARP) heating facility allows scientists to test current theories of plasma physics to gain a better understanding of the underlying mechanisms at work in the lower ionosphere. One powerful technique for diagnosing radio frequency interactions in the ionosphere is to use ground-based optical instrumentation. High-frequency (HF), heater-induced artificial airglow observations can be used to diagnose electron energies and distributions in the heated region, illuminate natural and/or artificially induced ionospheric irregularities, determine ExB plasma drifts, and measure quenching rates by neutral species. Artificial airglow is caused by HF-accelerated electrons colliding with various atmospheric constituents, which in turn emit a photon. The most common emissions are 630.0 nm O(1D), 557.7 nm O(1S), and 427.8 nm N2+(1NG). Because more photons will be emitted in regions of higher electron energization, it may be possible to use airglow imaging to map artificial field-aligned irregularities at a particular altitude range in the ionosphere. Since fairly wide field-of-view imagers are typically deployed in airglow campaigns, it is not well-known what meter-scale features exist in the artificial airglow emissions. Rocket data show that heater-induced electron density variations, or irregularities, consist of bundles of ~10-m-wide magnetic field-aligned filaments with a mean depletion depth of 6% [Kelley et al., 1995]. These bundles themselves constitute small-scale structures with widths of 1.5 to 6 km. Telescopic imaging provides high resolution spatial coverage of ionospheric irregularities and goes hand in hand with other observing techniques such as GPS scintillation, radar, and ionosonde. Since airglow observations can presumably image ionospheric irregularities (electron density variations), they can be used to determine the spatial scale variation, the fill factor, and the lifetime characteristics of

  3. A HF EM installation allowing simultaneous whole body and deep local EM hyperthermia.

    Science.gov (United States)

    Mazokhin, V N; Kolmakov, D N; Lucheyov, N A; Gelvich, E A; Troshin, I I

    1999-01-01

    The structure and main features of a HF EM installation based upon a new approach for creating electromagnetic fields destined for whole body (WBH) and deep local (DLH) hyperthermia are discussed. The HF EM field, at a frequency of 13.56 MHz, is created by a coplanar capacity type applicator positioned under a distilled water filled bolus that the patient is lying on. The EM energy being released directly in the deep tissues ensures effective whole body heating to required therapeutic temperatures of up to 43.5 degrees C, whereas the skin temperature can be maintained as low as 39-40.5 degrees C. For DLH, the installation is equipped with additional applicators and a generator operating at a frequency of 40.68 MHz. High efficiency of the WBH applicator makes it possible to carry out the WBH procedure without any air-conditioning cabin. Due to this, a free access to the patient's body during the WBH treatment is provided and a simultaneous WBH/DLH or WBH/LH procedure by means of additional applicators is possible. Controllable power output in the range of 100-800 W at a frequency of 13.56 MHz and 50-350 W at a frequency of 40.68 MHz allows accurate temperature control during WBH, DLH and WBH/DLH procedures. SAR patterns created by the WBH and DLH applicators in a liquid muscle phantom and measured by means of a non-perturbing E-dipole are investigated. The scattered EM field strength measured in the vicinity of the operating installation during the WBH, DLH and WBH/DLH procedures does not exceed security standards. Examples of temperature versus time graphs in the course of WBH, DLH and WBH/DLH procedures in clinics are presented. The installation is successfully used in leading oncological institutions of Russia and Belarus, though combined WBH/DLH procedures are evidently more complicated and demand thorough planning and temperature measurements to avoid overheating.

  4. CUTLASS HF radar observations of high-velocity E-region echoes

    Directory of Open Access Journals (Sweden)

    M. V. Uspensky

    Full Text Available A short event of high-velocity E-region echo observations by the Pykkvibaer HF radar is analysed to study echo parameters and the echo relation to the Farley-Buneman plasma instability. The echoes were detected in several beams aligned closely to the magnetic L-shell direction. Two echo groups were identified: one group corresponded to the classical type 1 echoes with velocities close to the nominal ion-acoustic speed of 400 ms1 , while the other group had significantly larger velocities, of the order of 700 ms1 . The mutual relationship between the echo power, Doppler velocity, spectral width and elevation angles for these two groups was studied. Plotting of echo parameters versus slant range showed that all ~700 ms1 echoes originated from larger heights and distances of 500–700 km, while all ~400 ms1 echoes came from lower heights and from farther distances; 700–1000 km. We argue that both observed groups of echoes occurred due to the Farley-Buneman plasma instability excited by strong ( ~70 mVm1 and uniformly distributed electric fields. We show that the echo velocities for the two groups were different because the echoes were received from different heights. Such a separation of echo heights occurred due to the differing amounts of ionospheric refraction at short and large ranges. Thus, the ionospheric refraction and related altitude modulation of ionospheric parameters are the most important factors to consider, when various characteristics of E-region decametre irregularities are derived from HF radar measurements.

    Key words. Ionosphere (ionospheric irregularities; plasma waves and instabilities; polar ionosphere

  5. Sensitivity of the downward to sweeping velocity ratio to the bypass flow percentage along a guide wall for downstream fish passage

    Science.gov (United States)

    Mulligan, Kevin; Towler, Brett; Haro, Alexander J.; Ahlfeld, David P.

    2017-01-01

    Partial-depth impermeable guidance structures (or guide walls) are used as a method to assist in the downstream passage of fish at a hydroelectric facility. However, guide walls can result in a strong downward velocity causing the approaching fish to pass below the wall and into the direction of the turbine intakes. The objective of this study was to describe how the ratio of the vertical velocity to the sweeping velocity magnitude changes along the full length and depth of a guide wall under a wide range of bypass flow percentages within a power canal. This paper focused on two guide wall configurations, each set at an angle of 45 ° to the approaching flow field and at a depth of 10 and 20 ft (3.05 and 6.10 m). The hydraulic conditions upstream of each guide wall configuration were shown to be impacted by a change in the bypass flow percentage, not only near the bypass but also at upstream sections of the guide wall. Furthermore, the effect of changing the bypass flow percentage was similar for both guide wall depths. In both cases, the effect of increasing the bypass flow percentage was magnified closer to the bypass and deeper in the water column along the guide wall.

  6. Influence of Indium-Percentage Variation on Dynamical Characteristics of InxGa1-xAs/GaAs(001) Quantum Dot Lasers

    CERN Document Server

    Borji, Mahdi Ahmadi

    2015-01-01

    The influence of indium percentage on dynamical characteristics of InxGa1-xAs/GaAs(001) quantum dot lasers (QDLs) is investigated. Energy levels of self-organized truncated-cone-shape QDs are calculated by means of the eight-band k.p model, and their dependence to indium percentage is surveyed. Then, by presenting a three-level model and numerical solution of the resulting rate equations, laser properties are determined. Our results show that inclusion of more indium gives rise in the reduced energy gap and electron-hole recombination energy. Moreover, lasing process for both Ground State (GS) and Excited States (ES) sound to be sensitive to indium percentage. It is shown that rise of indium percentage at fixed injected current results in the increased ES turn-on delay and GS photon number and 3dB modulation bandwidth, and decreased ES photon number, GS turn on delay, amplitude of relaxation oscillations, output power, and ES 3dB modulation bandwidth; but has no effect on threshold current and laser gain. At ...

  7. Ti insertion in the MTe5 (M = Zr, Hf structure type: Hf0.78Ti0.22Te5

    Directory of Open Access Journals (Sweden)

    Hoseop Yun

    2012-03-01

    Full Text Available The group 5 mixed-metal telluride, Hf0.78Ti0.22Te5 (hafnium titanium pentatelluride, is isostructural with the binary phases HfTe5 and ZrTe5 and forms a layered structure extending parallel to (010. The layers are made up from chains of bicapped metal-centered trigonal prisms and zigzag Te chains. The metal site (site symmetry m2m is occupied by statistically disordered Hf [78.1 (5%] and Ti [21.9 (5%]. In addition to the regular Te—Te pair [2.7448 (13 Å] forming the short base of the equilateral triangle of the trigonal prism, an intermediate Te...Te separation [2.9129 (9 Å] is also found. The classical charge balance of the compound can be described as [M4+][Te2−][Te22−][Te20] (M = Hf, Ti. The individual metal content can vary in different crystals, apparently forming a random substitutional solid solution (Hf1-xTixTe5, with 0.15 ≤ x ≤ 0.22.

  8. First-principles calculated spin-gapless semiconducting behavior in quaternary VCoHfGa and CrFeHfGa Heusler compounds

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xiude; Wu, Xiaolin [Institute of Theoretical Physics, Zunyi Normal College, Zunyi 563002 (China); Wu, Bo, E-mail: fqwubo@zync.edu.cn [Institute of Theoretical Physics, Zunyi Normal College, Zunyi 563002 (China); School of Marine Science and Technology, Northwestern Polytechnical University, Xian 710072 (China); Feng, Yu [School of Physical Science and Technology, Southwest University, Chongqing 400715 (China); Li, Ping [Institute for Clean Energy & Advanced Materials (ICAEM), Southwest University, Chongqing 400715 (China); Huang, Haishen [Institute of Theoretical Physics, Zunyi Normal College, Zunyi 563002 (China)

    2016-07-15

    Highlights: • Structural, electronic and magnetic properties of quaternary Heusler alloy [VCo,CrFe]HfGa were detected theoretically. • The quaternary Heusler alloy [VCo,CrFe]HfGa are (or are nearly) spin gapless semiconductors at the lowest energy state. • The ferromagnetic coupling plays an important role in magnetism. - Abstract: By using generalized gradient approximation (GGA) scheme within the density functional theory (DFT), the structural, electronic and magnetic properties of LiMgPdSn-type quaternary Heusler alloy CrFeHfGa and VCoHfGa were detected compressively. The results reveal that the two alloys are (or are nearly) potential spin gapless semiconductors with a magnetic moment of 3 μ{sub B} per primitive cell and the minority-spin gap of 0.8 eV and 0.6 eV at Fermi level (ε{sub F}) during the rate of lattice change of about −5%, respectively. We deduce that the ferromagnetic coupling among transitional metals plays an important role in magnetism of Heusler alloy [CrFe,VCo]HfGa.

  9. First-principles study of the (001) surface of cubic PbHfO3 and BaHfO3

    Institute of Scientific and Technical Information of China (English)

    Ni Guang-Xin; Wang Yuan-Xu

    2009-01-01

    Using first-principles techniques, we investigate the (001) surfaces of cubic PbHfO3 (PHO) and BaHfO3 (BHO) terminated with both AO (A=Pb and Ba) and HfO2- Surface structure, partial density of states, band structure, and surface energy are obtained. The BaO surface is found to be similar to its counterpart in BHO. For the HfO2-terminated surface of cubic PHO, the largest relaxation appears on the second-layer atoms but not on the first-layer ones. The analysis of the structure relaxation parameters reveals that the rumpling of the (001) surface for PHO is stronger than that for BHO. The surface thermodynamic stability is explored, and it is found that both the PbO- and the BaO-terminated surfaces are more stable than the HfO2-terminated surfaces for PHO and BHO, respectively. The surface energy calculations show that the (001) surface of PHO is more easily constructed than that of BHO.

  10. Formulation, Pretreatment, and Densification Options to Improve Biomass Specifications for Co-Firing High Percentages with Coal

    Energy Technology Data Exchange (ETDEWEB)

    Jaya Shankar Tumuluru; J Richard Hess; Richard D. Boardman; Shahab Sokhansanj; Christopher T. Wright; Tyler L. Westover

    2012-06-01

    There is a growing interest internationally to use more biomass for power generation, given the potential for significant environmental benefits and long-term fuel sustainability. However, the use of biomass alone for power generation is subject to serious challenges, such as feedstock supply reliability, quality, and stability, as well as comparative cost, except in situations in which biomass is locally sourced. In most countries, only a limited biomass supply infrastructure exists. Alternatively, co-firing biomass alongwith coal offers several advantages; these include reducing challenges related to biomass quality, buffering the system against insufficient feedstock quantity, and mitigating the costs of adapting existing coal power plants to feed biomass exclusively. There are some technical constraints, such as low heating values, low bulk density, and grindability or size-reduction challenges, as well as higher moisture, volatiles, and ash content, which limit the co-firing ratios in direct and indirect co-firing. To achieve successful co-firing of biomass with coal, biomass feedstock specifications must be established to direct pretreatment options in order to modify biomass materials into a format that is more compatible with coal co-firing. The impacts on particle transport systems, flame stability, pollutant formation, and boiler-tube fouling/corrosion must also be minimized by setting feedstock specifications, which may include developing new feedstock composition by formulation or blending. Some of the issues, like feeding, co-milling, and fouling, can be overcome by pretreatment methods including washing/leaching, steam explosion, hydrothermal carbonization, and torrefaction, and densification methods such as pelletizing and briquetting. Integrating formulation, pretreatment, and densification will help to overcome issues related to physical and chemical composition, storage, and logistics to successfully co-fire higher percentages of biomass ( > 40

  11. Recent progress in AMS measurement of 182Hf at the CIAE

    Institute of Scientific and Technical Information of China (English)

    LI Zhen-Yu; LI Heng; WU Shao-Yong; YUAN Jian; JIANG Shan; HE Ming; DONG Ke-Jun; HE Guo-Zhu; LI Chao-Li; HE Xian-Wen; ZHANG Wei; HU Hao; ZHENG Guo-Wen

    2012-01-01

    In order to improve the accuracy of accelerator mass spectrometry (AMS) measurement for 182Hf/180Hf,a series of measurements have been taken in the AMS laboratory at the China Institute of Atomic Energy (CIAE).The major ones include the instantaneous monitoring of 180HfF-5current,testing the stability of transmission,the alternate measurements of an unknown sample and standard,and the origin identification and minimization of background 182W.The experimental details and the improvement in the measurement accuracy,as well as some useful suggestions for better satisfying the requirements of certain practical applications,are presented in this paper.

  12. Crystal structure of Na2HfSi2O7 by Rietveld refinement

    Directory of Open Access Journals (Sweden)

    Nicolas Massoni

    2016-10-01

    Full Text Available The structure of triclinic disodium hafnium disilicate, Na2HfSi2O7, has been determined by laboratory powder X-ray diffraction and refined by the Rietveld refinement. The structure is a framework made of alternate layers of HfO6 octahedra and SiO4 tetrahedra linked by common O atoms. Sodium atoms are located in the voids of the framework, aligned into tunnels along the [010] direction. Na2HfSi2O7 is isostructural with the parakeldyshite Na2ZrSi2O7 phase.

  13. Structural and thermal properties of Cu-Hf-Ti bulk amorphous alloys

    Science.gov (United States)

    Rontó, V.; Nagy, E.; Svéda, M.; Roósz, A.; Tranta, F.

    2009-01-01

    Cu-Hf-Ti amorphous alloys are high strength and wear resistant materials. Master alloys of Cu57.5Hf27.5Ti15 and Cu57.5Hf25Ti17.5 ternary alloys have been prepared by arc melting, and wedge and rod shaped samples have been cast by centrifugal casting. Liquidus and solidus temperatures of the alloys were determined by DTA. The fully amorphous size was determined by X-ray diffraction. Thermodynamic properties of the amorphous alloys were studied by DSC measurements and Kissinger analyses were performed.

  14. Graphene contacts to a HfSe2/SnS2 heterostructure

    Science.gov (United States)

    Su, Shanshan; Das, Protik; Ge, Supeng; Lake, Roger K.

    2017-02-01

    Two-dimensional (2D) heterostructures and all-2D contacts are of high interest for electronic device applications, and the SnS2/HfSe2 bilayer heterostructure with graphene contacts has some unique, advantageous properties. The SnS2/HfSe2 heterostructure is interesting because of the strong intermixing of the two conduction bands and the large work function of the SnS2. The band lineup of the well separated materials indicates a type II heterostructure, but the conduction band minimum of the SnS2/HfSe2 bilayer is a coherent superposition of the orbitals from the two layers with a spectral weight of 60% on the SnS2 and 40% on the HfSe2 for AA stacking. These relative weights can be either increased or reversed by an applied vertical field. A 3 ×3 supercell of graphene and a 2 ×2 supercell of SnS2/HfSe2 have a lattice mismatch of 0.1% and both the SnS2/HfSe2 conduction band at M and the graphene Dirac point at K are zone-folded to Γ . Placing graphene on the SnS2/HfSe2 bilayer results in large n-type charge transfer doping of the SnS2/HfSe2 bilayer, on the order of 1013/cm2, and the charge transfer is accompanied by a negative Schottky barrier contact for electron injection from the graphene into the SnS2/HfSe2 bilayer conduction band. Binding energies and the anti-crossing gaps of the graphene and the SnS2/HfSe2 electronic bands both show that the coupling of graphene to the HfSe2 layer is significantly larger than its coupling to the SnS2 layer. A tunneling Hamiltonian estimate of the contact resistance of the graphene to the SnS2/HfSe2 heterostructure predicts an excellent low-resistance contact.

  15. Control of photoassociation reaction F+H→HF with ultrashort laser pulse

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The laser-induced vibrational state-selectivity of product HF in photoassociation reaction H+F→HF is theoretically investigated by using the time-dependent quantum wave packet method. The population transfer process from the continuum state down to the bound vibrational states can be controlled by the driving laser. The effects of laser pulse parameters and the initial momentum of the two collision atoms on the vibrational population of the product HF are discussed in detail. Photodissociation accompanied with the photoassociation process is also described.

  16. [18F]Fluoride recovery via gaseous [18F]HF

    DEFF Research Database (Denmark)

    Mathiessen, Bente; Jensen, Mikael; Zhuravlev, Fedor

    2011-01-01

    Acidification of target water with H2SO4 in a specially constructed glassy carbon/polyethylene apparatus allowed for recovery of up to 82% of [18F]fluoride as [18F]HF gas. The [18F]HF distillate was found to be acid-free but moist; when passed through a solution of tBuPh2SiOTf, it yielded [18F......]tBuPh2SiF. The multivariate design of experiment showed that the key to high yield of [18F]HF was the efficient degassing of the reaction mixture....

  17. The role of phosphates for the Lu-Hf chronology of meteorites

    Science.gov (United States)

    Debaille, Vinciane; Van Orman, James; Yin, Qing-Zhu; Amelin, Yuri

    2017-09-01

    The 176Lu-176Hf isotopic system is widely used for dating and tracing cosmochemical and geological processes, but still suffers from two uncertainties. First, Lu-Hf isochrons for some early Solar System materials have excess slope of unknown origin that should not be expected for meteorites with ages precisely determined with other isotopic chronometers. This observation translates to an apparent Lu decay constant higher than the one calculated by comparing ages obtained with various dating methods on terrestrial samples. Second, unlike the well constrained Sm/Nd value (to within 2%) for the chondritic uniform reservoir (CHUR), the Lu/Hf ratios in chondrites vary up to 18% when considering all chondrites, adding uncertainty to the Lu/Hf CHUR value. In order to better understand the Lu-Hf systematics of chondrites, we analyzed mineral fractions from the Richardton H5 chondrite to construct an internal Lu-Hf isochron, and set up a numerical model to investigate the effect of preferential diffusion of Lu compared to Hf from phosphate, the phase with the highest Lu-Hf ratio in chondrites, to other minerals. The isochron yields an age of 4647 ± 210 million years (Myr) using the accepted 176Lu decay constant of 1.867 ± 0.008 ×10-11yr-1. Combining this study with the phosphate fractions measured in a previous study yields a slope of 0.08855 ± 0.00072, translating to a 176Lu decay constant of 1.862 ± 0.016 ×10-11yr-1 using the Pb-Pb age previously obtained, in agreement with the accepted value. The large variation of the Lu/Hf phosphates combined with observations in the present study identify phosphates as the key in perturbing Lu-Hf dating and generating the isochron slope discrepancy. This is critical as apatite has substantially higher diffusion rates of rare earth elements than most silicate minerals that comprise stony meteorites. Results of numerical modeling depending of temperature peak, size of the grains and duration of the metamorphic event, show that

  18. Interaction of La2O3 capping layers with HfO2 gate dielectrics

    Science.gov (United States)

    Copel, M.; Guha, S.; Bojarczuk, N.; Cartier, E.; Narayanan, V.; Paruchuri, V.

    2009-11-01

    We report the effect of La2O3 capping layers on HfO2/SiO2/Si dielectrics, proposed for use in threshold voltage tuning of field effect transistors. Depth profiling with medium energy ion scattering shows that an initial surface layer of La2O3 diffuses through the HfO2 at elevated temperatures, ultimately converting some of the thin interfacial SiO2 into a silicate. Core-level photoemission measurements indicate that the additional band-bending induced by the La2O3 only appears after diffusion, and the added charge resides between the HfO2 and the substrate.

  19. Temperature Effect on Photovoltaic Modules Power Drop

    Directory of Open Access Journals (Sweden)

    Qais Mohammed Aish

    2015-06-01

    Full Text Available In order to determine what type of photovoltaic solar module could best be used in a thermoelectric photovoltaic power generation. Changing in powers due to higher temperatures (25oC, 35oC, and 45oC have been done for three types of solar modules: monocrystalline , polycrystalline, and copper indium gallium (di selenide (CIGS. The Prova 200 solar panel analyzer is used for the professional testing of three solar modules at different ambient temperatures; 25oC, 35oC, and 45oC and solar radiation range 100-1000 W/m2. Copper indium gallium (di selenide module has the lowest power drop (with the average percentage power drop 0.38%/oC while monocrystalline module has the highest power drop (with the average percentage power drop 0.54%/oC, while polycrystalline module has a percentage power drop of 0.49%/oC.

  20. Percentage of vestibular dysfunction in 361 elderly citizens responding to a newspaper advertisement

    DEFF Research Database (Denmark)

    Smærup, Michael; Læssøe, Uffe; Damsgaard, Else Marie

    2011-01-01

    Percentage of Vestibular Dysfunction in 361 Elderly Citizens Responding to a Newspaper Advertisement. Brandt M, Grönvall E, Henriksen JJ, Larsen SB, Læssøe U, Mørch MM, Damsgaard EM Introduction Elderly patients with vestibular dysfunction have an eight-fold increased risk of falling compared...... to other fall patients. We believe that elderly patients with vestibular dysfunction either don’t consult their GP or have been abandoned by their GP. The aim of this study was to identify the percentage of vestibular dysfunction among elderly citizens with complaints of dizziness responding to a newspaper...... advertisement. Method To recruit elderly citizens with dizziness we advertised in a local newspaper. A telephone interview with the respondents was done by a physiotherapist (PT). If the PT concluded that the reason for the dizziness could be vestibular dysfunction the citizen was invited to further...

  1. Calculation of the C3A Percentage in High Sulfur Clinker

    Directory of Open Access Journals (Sweden)

    Sayed Horkoss

    2010-01-01

    Full Text Available The aim of this paper is to clarify the influence of the clinker SO3 on the amount of C3A. The calculation of the cement phases percentages is based on the research work, Calculation of the Compounds in Portland Cement, published by Bogue in 1929 .The usage of high sulphur fuels, industrial wastes, and tires changes completely the working condition of Bogue because the assumed phase compositions may change. The results prove that increasing the amount of SO3 in the low alkali clinker decreases the percentages of C3A due to the high incorporation of alumina in the clinker phases mainly C2S and C3S. The correlation is linear till the clinker SO3 reaches the 2%. Over that the influence of the clinker SO3 became undetectable. A new calculation method for the determination of the C3A in the high sulphur and low alkali clinker was proposed.

  2. Changes in percentage of lymphocyte subsets after 131I treatment in patients with differentiated thyroid cancer

    Institute of Scientific and Technical Information of China (English)

    LUO Quan-Yong; CHEN Li-Bo; YU Yong-Li; LU Han-Kui; ZHU Rui-Sen

    2005-01-01

    To monitor the extent and the duration of lymphocyte subset changes in patients with thyroid carcinoma undergoing therapeutic 131I administration, the percentage of lymphocyte subsets were serially analyzed before and after 131I treatment. In patients who received 1850 MBq of 131I for ablation of thyroid remnants, only for NK cells and B cells showed a significant reduction. In patients received 3700 MBq of 131I for treatment of local lymph node metastases, NK cells, B cells and CD4+ were found decreased. In patients received 7400 MBq of 131I for treatment of distant metastases, NK cells, B cells and CD4+ and CD8+ were all affected. However, there is no significant reduction compared to the baseline in the percentage of all lymphocyte subsets three months after 131I treatment. The results show that the sensitivity of lymphocytes to 131I internal radiation depends upon lymphocyte phenotype and 131I activity. The immunosuppression effects are temporary and reversible.

  3. Dietary lecithin improves dressing percentage and decreases chewiness in the longissimus muscle in finisher gilts.

    Science.gov (United States)

    Akit, H; Collins, C L; Fahri, F T; Hung, A T; D'Souza, D N; Leury, B J; Dunshea, F R

    2014-03-01

    The influence of dietary lecithin at doses of 0, 4, 20 or 80 g/kg fed to finisher gilts for six weeks prior to slaughter on growth performance, carcass quality and pork quality was investigated. M. longissimus lumborum (loin) was removed from 36 pig carcasses at 24h post-mortem for Warner-Bratzler shear force, compression, collagen content and colour analyses. Dietary lecithin increased dressing percentage (P=0.009). Pork chewiness and collagen content were decreased by dietary lecithin (Plecithin had no effect on shear force, cohesiveness or hardness (P>0.05, respectively). Dietary lecithin reduced loin muscle L* values and increased a* values (Plecithin improved dressing percentage and resulted in less chewy and less pale pork. © 2013.

  4. A first-principles high-pressure study of Hf2PX (X=B, C, N)

    Science.gov (United States)

    Li, Hui; Luo, Zhili; Liu, Zhe; Sun, Guodong; Wang, Zhenjun

    2017-06-01

    New members of MAX family Hf2PX (X=B, C, N) were studied by first-principles calculations under pressure range of 0-100 GPa. Their structural, elastic and electronic properties were reported. The results show that they are energetically stable at zero pressure and mechanically stable under pressure range from 0 to 100 GPa. It reveals that Hf2PB>Hf2PC>Hf2PN for the structural parameters of a and V, and Hf2PBpressure environments.

  5. Fabrication and characteristics of high-K HfO2 gate dielectrics on n-germanium

    Institute of Scientific and Technical Information of China (English)

    Han De-Dong; Kang Jin-Feng; Liu Xiao-Yan; Sun Lei; Luo Hao; Han Ru-Qi

    2007-01-01

    This paper reports that the high-K HfO2 gate dielectrics are fabricated on n-germanium substrates by sputtering Hf on Ge and following by a furnace annealing. The impacts of sputtering ambient, annealing ambient and annealing temperature on the electrical properties of high-K HfO2 gate dielectrics on germanium substrates are investigated.Experimental results indicate that high-K HfO2 gate dielectrics on germanium substrates with good electrical characteristics are obtained, the electrical properties of high-K HfO2 gate dielectrics is strongly correlated with sputtering ambient, annealing ambient and annealing temperature.

  6. Antioxidant Enzymes, Membrane Stability and Essential Oil Percentage of Balm under Drought Stress

    Directory of Open Access Journals (Sweden)

    M Ardakani

    2011-01-01

    Full Text Available Abstract In this research, the effect of drought stress on antioxidant enzymes, membrane stability and essential oil percentage in Balm (Melissa officinalis L. has been evaluted under field conditions. Experimental design was complete randomized block design with 4 replications. The treatments included: T1 (control; non stress, T2 (80%FC, T3 (60%FC, T4 (40%FC and T5 (20%FC. Results showed that there was a significant differences (P

  7. 29 CFR 778.503 - Pseudo “percentage bonuses.”

    Science.gov (United States)

    2010-07-01

    ... additional overtime compensation is paid: Week 1—40 hours worked: 40 hours at $5.62 per hour $224.80 Percentage of total earnings bonus at 33.45% of $224.80 75.20 Total 300.00 Week 2—43 hours worked: 40 hours... bonus at 19.96% of $250.09 49.91 Total 300.00 Week 3—48 hours worked: 40 hours at $5.62 per......

  8. The Equation for Prediction of Lean Meat Percentage by Hennessy Grading Probe in Croatia

    Directory of Open Access Journals (Sweden)

    Goran Kušec

    2011-10-01

    Full Text Available The dissection experiment was carried out on 120 swine carcasses slaughtered in several Croatian slaughterhouses. The carcasses were selected on the basis of rather large sample of backfat measurements obtained by method for lean percentage prediction approved in Croatia, regardless of the carcass weight. After 24 hours of cooling, left sides of the carcasses were dissected according to EU reference methods (Commission Regulation No 3127/94; Walstra and Merkus, 1996. Dissected lean percentage was assessed according to the Commission Regulation (EC No 1249/2008. The aim of the present study was to construct a formula for online classification of the pig carcasses by Hennessy Grading Probe (HGP, an approved referent device in Republic of Croatia. The formula for HGP device was assessed according to the prediction ability i.e. the standard error of prediction-RMSEP (root mean square error of prediction that is estimated using cross-validation “leave-one-out”. The obtained equation was: M% = 59.603676 - 0.864 * S + 0.192 * M, having RMSEP 2.21 that is satisfactory according to European regulations. Mean values of the fat depth and muscle thickness in the data set used for the construction of the formula was 16.41 ± 4.11 mm and 61.19 ± 9.05 mm, respectively. Mean lean percentage obtained by dissection was 57.17 ± 4.86% that did not differ statistically from the lean percentage estimated by the formula which was 57.72 ± 4.38%.

  9. The Equation for Prediction of Lean Meat Percentage by Hennessy Grading Probe in Croatia

    Directory of Open Access Journals (Sweden)

    Goran Kušec

    2011-12-01

    Full Text Available The dissection experiment was carried out on 120 swine carcasses slaughtered in several Croatian slaughterhouses. The carcasses were selected on the basis of rather large sample of backfat measurements obtained by method for lean percentage prediction approved in Croatia, regardless of the carcass weight. After 24 hours of cooling, left sides of the carcasses were dissected according to EU reference methods (Commission Regulation No 3127/94; Walstra and Merkus, 1996. Dissected lean percentage was assessed according to the Commission Regulation (EC No 1249/2008. The aim of the present study was to construct a formula for online classification of the pig carcasses by Hennessy Grading Probe (HGP, an approved referent device in Republic of Croatia. The formula for HGP device was assessed according to the prediction ability i.e. the standard error of prediction-RMSEP (root mean square error of prediction that is estimated using cross-validation “leave-one-out”. The obtained equation was: M% = 59.603676 - 0.864 * S + 0.192 * M, having RMSEP 2.21 that is satisfactory according to European regulations. Mean values of the fat depth and muscle thickness in the data set used for the construction of the formula was 16.41 ± 4.11 mm and 61.19 ± 9.05 mm, respectively. Mean lean percentage obtained by dissection was 57.17 ± 4.86% that did not differ statistically from the lean percentage estimated by the formula which was 57.72 ± 4.38%.

  10. Effect of percentage of low plastic fines on the unsaturated shear strength of compacted gravel soil

    Directory of Open Access Journals (Sweden)

    Kamal Mohamed Hafez Ismail Ibrahim

    2015-06-01

    Full Text Available Low plastic fines in gravel soils affect its unsaturated shear strength due to the contribution of matric suction that arises in micro and macro pores found within and between aggregates. The shear strength of five different types of prepared gravel soils is measured and is compared with a theoretical model (Fredlund et al., 1978 to predict the unsaturated shear strength. The results are consistent to a great extent except the case of dry clayey gravel soil. It is also found that on inundation of gravel soils containing plastic fines greater than 12% a considerable reduction in both the strength and the stiffness modulus is noticed. This 12% percentage is close to the accepted 15% percentage of fines given by ASTM D4318 (American society for testing material. The angle of internal friction that arises due to matric suction decreases with the increase of degree of saturation of soil. The hysteresis of some tested gravel soils is measured and found that it increases by increasing the percentage of fines.

  11. Influence of N atomic percentages on cell attachment for CN$_x$ coatings

    Indian Academy of Sciences (India)

    D J Li; L F Niu

    2003-06-01

    Carbon film is an excellent candidate for use as a biocompatible coating due to its excellent properties. However, considerable attention has just been focused on the biocompatibility of diamond-like carbon (DLC) in recent years. It is difficult to find reports on the investigations of the biocompatibility of CN$_x$ so far. It is well known that CN$_x$ has similar structural characteristics as that of DLC. Its excellent mechanical and tribological properties are comparable to that of DLC. In addition, it is probable that the presence of nitrogen leads to a positive effect on biocompatibility. So, this work focusses on cell attachment of CN$_x$ coating and the relation between nitrogen atomic percentage and cell attachment. CN$_x$ coatings were prepared using magnetron sputtering under two N2 partial pressures for the evaluation of relation between nitrogen atomic percentage and cell attachment. Cell culture tests using human endothelial cells and mouse fibroblasts were performed. Both coatings resulted in no adverse effects on the cells in culture. Compared with CN$_x$ ( = 0.088), CN$_x$ ( = 0.149) film provided a better surface for normal cellular attachment, spreading and proliferation without apparent impairment of cell physiology. At the same time, the coatings exhibited excellent tribological and corrosion performance. XPS and AES analyses showed that higher nitrogen atomic percentage might lead to a positive effect on the cell attachment.

  12. Relationship between articulation paper mark size and percentage of force measured with computerized occlusal analysis.

    Science.gov (United States)

    Qadeer, Sarah; Kerstein, Robert; Kim, Ryan Jin Yung; Huh, Jung-Bo; Shin, Sang-Wan

    2012-02-01

    Articulation paper mark size is widely accepted as an indicator of forceful tooth contacts. However, mark size is indicative of contact location and surface area only, and does not quantify occlusal force. The purpose of this study is to determine if a relationship exists between the size of paper marks and the percentage of force applied to the same tooth. Thirty dentate female subjects intercuspated into articulation paper strips to mark occlusal contacts on their maxillary posterior teeth, followed by taking photographs. Then each subject made a multi-bite digital occlusal force percentage recording. The surface area of the largest and darkest articulation paper mark (n = 240 marks) in each quadrant (n = 60 quadrants) was calculated in photographic pixels, and compared with the force percentage present on the same tooth. Regression analysis shows a bi-variant fit of force % on tooth (Pforce indicated a low positive correlation. The coefficient of determination showed a low causative relationship between mark area and force (r(2) = 0.067). The largest paper mark in each quadrant was matched with the most forceful tooth in that same quadrant only 38.3% of time. Only 6 2/3% of mark surface area could be explained by applied occlusal force, while most of the mark area results from other factors unrelated to the applied occlusal force. The findings of this study indicate that size of articulation paper mark is an unreliable indicator of applied occlusal force, to guide treatment occlusal adjustments.

  13. Artificial neural networks for prediction of percentage of water absorption of geopolymers produced by waste ashes

    Indian Academy of Sciences (India)

    Ali Nazari

    2012-11-01

    In the present work, percentage of water absorption of geopolymers made from seeded fly ash and rice husk bark ash has been predicted by artificial neural networks. Different specimens, made from a mixture of fly ash and rice husk bark ash in fine and coarse form together with alkali activatormade of water glass and NaOH solution, were subjected to permeability tests at 7 and 28 days of curing. The curing regime was different: one set cured at room temperature until reaching to 7 and 28 days and the other sets were oven cured for 36 h at a range of 40–90 °C and then cured at room temperature for 7 and 28 days. To build the model, training and testing using experimental results from 120 specimens were conducted. According to these input parameters, in the neural networks model, the percentage of water absorption of each specimen was predicted. The training and testing results in the neural networks model have shown a strong potential for predicting the percentage of water absorption of the geopolymer specimens.

  14. A New Tree Cover Percentage Map in Eurasia at 500 m Resolution Using MODIS Data

    Directory of Open Access Journals (Sweden)

    Toshiyuki Kobayashi

    2013-12-01

    Full Text Available Global tree cover percentage is an important parameter used to understand the global environment. However, the available global percent tree cover products are few, and efforts to validate these maps have been limited. Therefore, producing a new broad-scale percent tree cover dataset is valuable. Our study was undertaken to map tree cover percentage, on a global scale, with better accuracy than previous studies. Using a modified supervised regression tree algorithm from Moderate Resolution Imaging Spectroradiometer (MODIS data of 2008, the tree cover percentage was estimated at 500 m resolution in Eurasia. Training data were created by simulation using reference data interpreted from Google Earth. We collected approximately 716 high-resolution images from Google Earth. The regression tree model was modified to fit those images for improved accuracy. Our estimation result was validated using 307 points. The root mean square error (RMSE between estimated and observed tree cover was 11.2%, and the weighted RMSE between them, in which five tree cover strata (0%–20%, 21%–40%, 41%–60%, 61%–80%, and 81%–100% were weighted equally, was 14.2%. The result was compared to existing global percent-scale tree cover datasets. We found that existing datasets had some pixels with estimation error of more than 50% and each map had different characteristics. Our map could be an alternative dataset and other existing datasets could be modified using our resultant map.

  15. Comparison of BMI and percentage of body fat of Indian and German children and adolescents.

    Science.gov (United States)

    Janewa, Vanessa Schönfeld; Ghosh, Arnab; Scheffler, Christiane

    2012-01-01

    Today, serious health problems as overweight and obesity are not just constricted to the developed world, but also increase in the developing countries (Prentice 2006, Ramachandram et al. 2002). Focusing on this issue, BMI and percentage of body fat were compared in 2094 schoolchildren from two cross-sectional studies from India and Germany investigated in 2008 and 2009. The German children are in all age groups significantly taller, whereas the Indian children show higher values in BMI (e.g. 12 years: Indian: around 22 kg/m2; German: around 19 kg/m2) and in the percentage of body fat (e.g. 12 years: Indian: around 27%; German: around 18-20%) in most of the investigated age groups. The Indian children have significantly higher BMI between 10 and 13 (boys) respectively 14 years (girls). Indian children showed significant higher percentage of body fat between 10 and 15 years (boys) and between 8 and 16 years (girls). The difference in overweight between Indian and German children was strongest at 11 (boys) and 12 (girls) years: 70% of the Indian but 20% of the German children were classified as overweight. In countries such as India that undergo nutritional transition, a rapid increase in obesity and overweight is observed. In contrast to the industrialized countries, the risk of overweight in developing countries is associated with high socioeconomic status. Other reasons of the rapid increase of overweight in the developing countries caused by different environmental or genetic factors are discussed.

  16. The effects of water parameters on monthly seagrass percentage cover in Lawas, East Malaysia.

    Science.gov (United States)

    Ahmad-Kamil, E I; Ramli, R; Jaaman, S A; Bali, J; Al-Obaidi, J R

    2013-01-01

    Seagrass is a valuable marine ecosystem engineer. However, seagrass population is declining worldwide. The lack of seagrass research in Malaysia raises questions about the status of seagrasses in the country. The seagrasses in Lawas, which is part of the coral-mangrove-seagrass complex, have never been studied in detail. In this study, we examine whether monthly changes of seagrass population in Lawas occurred. Data on estimates of seagrass percentage cover and water physicochemical parameters (pH, turbidity, salinity, temperature, and dissolved oxygen) were measured at 84 sampling stations established within the study area from June 2009 to May 2010. Meteorological data such as total rainfall, air temperature, and Southern Oscillation Index were also investigated. Our results showed that (i) the monthly changes of seagrass percentage cover are significant, (ii) the changes correlated significantly with turbidity measurements, and (iii) weather changes affected the seagrass populations. Our study indicates seagrass percentage increased during the El-Nino period. These results suggest that natural disturbances such as weather changes affect seagrass populations. Evaluation of land usage and measurements of other water physicochemical parameters (such as heavy metal, pesticides, and nutrients) should be considered to assess the health of seagrass ecosystem at the study area.

  17. Effects of Aloe vera on dressing percentage and haemato-biochemidal parameters of broiler chickens

    Directory of Open Access Journals (Sweden)

    Jagmohan Singh

    2013-09-01

    Full Text Available Aim: To evaluate the effects of Aloe vera on dressing percentage and hemato-biochemical parameters of broiler chickens.Materials and Methods: A total of 90 chicks were used in this study. They were randomly allocated into 3 treatment groups.Fresh Aloe vera leaf juice (ALJ was prepared and administered to the test group T3 at the rate of 20 g/Lin drinking water daily.This study was carried out for 42 days. Dressing percentage and hemato-biochemical parameters were recorded at the end ofexperiment.Results: Group that was given Aloe vera (T3 showed numerically higher dressing percentage as compared to control group(T1 and drug control group (T2. It also showed significantly (P0.05 differences were observed in other parameters among all the treatment groups.Conclusion: Aloe vera has potential to be a growth promoter in broiler chicks and its growth promoting effects are comparableto that of antibiotic growth promoter (AGP.

  18. Low modulus Ti-Nb-Hf alloy for biomedical applications.

    Science.gov (United States)

    González, M; Peña, J; Gil, F J; Manero, J M

    2014-09-01

    β-Type titanium alloys with a low elastic modulus are a potential strategy to reduce stress shielding effect and to enhance bone remodeling in implants used to substitute failed hard tissue. For biomaterial application, investigation on the mechanical behavior, the corrosion resistance and the cell response is required. The new Ti25Nb16Hf alloy was studied before and after 95% cold rolling (95% C.R.). The mechanical properties were determined by tensile testing and its corrosion behavior was analyzed by potentiostatic equipment in Hank's solution at 37°C. The cell response was studied by means of cytotoxicity evaluation, cell adhesion and proliferation measurements. The stress-strain curves showed the lowest elastic modulus (42GPa) in the cold worked alloy and high tensile strength, similar to that of Ti6Al4V. The new alloy exhibited better corrosion resistance in terms of open circuit potential (EOCP), but was similar in terms of corrosion current density (iCORR) compared to Ti grade II. Cytotoxicity studies revealed that the chemical composition of the alloy does not induce cytotoxic activity. Cell studies in the new alloy showed a lower adhesion and a higher proliferation compared to Ti grade II presenting, therefore, mechanical features similar to those of human cortical bone and, simultaneously, a good cell response.

  19. Anomalous phenomena on HF radio paths during geomagnetic disturbances

    Science.gov (United States)

    Blagoveshchenskii, D. V.

    2016-07-01

    We analyze ionospheric oblique sounding data on three high-latitude and one high-latitude-midlatitude HF radio paths for February 15 and 16, 2014, when two substorms and one magnetic storm occurred. We investigate cases of anomalous propagation of signals: their reflection from sporadic layer Es, lateral reflections, type "M" or "N" modes, the presence of traveling ionospheric disturbances, and the diffusivity of signals and triplets. The most significant results are the following. In geomagnetically undisturbed times, sporadic Es-layers with reduced maximum observed frequencies (MOF Es) on three high-latitude paths were observed in both days. The values of MOF Es during disturbances are large, which leads to the screening of other oblique sounding signals reflected from the ionosphere. On all four paths, the most frequently traveling ionospheric disturbances due to the terminator were observed in quiet hours from 03:00 to 15:00 UT on the first day and from 06:00 to 13:00 UT on the second day of the experiment. In addition, both the sunset terminator and the magnetic storm on the high-latitude-mid-latitude path were found to generate traveling ionospheric disturbances jointly. No such phenomenon was found on high-latitude paths.

  20. Equatorial ionospheric disturbance observed through a transequatorial HF propagation experiment

    Directory of Open Access Journals (Sweden)

    T. Maruyama

    2006-07-01

    Full Text Available A transequatorial radio-wave propagation experiment at shortwave frequencies (HF-TEP was done between Shepparton, Australia, and Oarai, Japan, using the radio broadcasting signals of Radio Australia. The receiving facility at Oarai was capable of direction finding based on the MUSIC (Multiple Signal Classification algorithm. The results were plotted in azimuth-time diagrams (AT plots. During the daytime, the propagation path was close to the great circle connecting Shepparton and Oarai, thus forming a single line in the AT plots. After sunset, off-great-circle paths, or satellite traces in the AT plot, often appeared abruptly to the west and gradually returned to the great circle direction. However, there were very few signals across the great circle to the east. The off-great-circle propagation was very similar to that previously reported and was attributed to reflection by an ionospheric structure near the equator. From the rate of change in the direction, we estimated the drift velocity of the structure to range mostly from 100 to 300 m/s eastward. Multiple instances of off-great-circle propagation with a quasi-periodicity were often observed and their spatial distance in the east-west direction was within the range of large-scale traveling ionospheric disturbances (LS-TIDs. Off-great-circle propagation events were frequently observed in the equinox seasons. Because there were many morphological similarities, the events were attributed to the onset of equatorial plasma bubbles.

  1. A method for combined Sr-Nd-Hf isotopic analysis of <10 mg dust samples: implication for ice core science

    Science.gov (United States)

    Ujvari, Gabor; Wegner, Wencke; Klötzli, Urs

    2017-04-01

    Aeolian mineral dust particles below the size of 10-20 μm often experience longer distance transport in the atmosphere, and thus Aeolian dust is considered an important tracer of large-scale atmospheric circulation. Since ice core dust is purely Aeolian in origin, discrimination of its potential source region(s) can contribute to a better understanding of past dust activity and climatic/environmental causes. Furthermore, ice core dust source information provides critical experimental constraints for model simulations of past atmospheric circulation patterns [1,2]. However, to identify dust sources in past dust archives such as ice cores, the mineralogy and geochemistry of the wind-blown dust material must be characterized. While the amount of dust in marine cores or common terrestrial archives is sufficient for different types of analyses and even for multiple repeat measurements, dust content in ice cores is usually extremely low even for the peak dusty periods such as the Last Glacial Maximum (LGM) (5-8 mg dust/kg ice; [3]). Since the most powerful dust fingerprinting methods, such as REE composition and Sr-Nd-Pb isotopic analyses are destructive there is a clear need to establish sequential separation techniques of Sr, Nd, Pb and other REEs to get the most information out of small (5-10 mg) dust samples recovered from ice cores. Although Hf isotopes have recently been added as a robust tool of aerosol/dust source discrimination (e.g. [4,5,6,7]), precise Hf isotopic measurements of small (Central Europe (NUS), China (BEI) and the US (JUD) were processed (all acetic acid treated for carbonate removal, i.e. aluminosilicate fractions were analysed). Sr isotopic compositions varied between the aliquots within a range of ˜0.00007 for the three samples. Comparison of these values with previously obtained 87Sr/86Sr isotopic ratios from the same samples (different acid/sample amounts) reveals that these values are very sensitive to the acetic acid treatment (acid

  2. Formation of Al2O3-HfO2 Eutectic EBC Film on Silicon Carbide Substrate

    Directory of Open Access Journals (Sweden)

    Kyosuke Seya

    2015-01-01

    Full Text Available The formation mechanism of Al2O3-HfO2 eutectic structure, the preparation method, and the formation mechanism of the eutectic EBC layer on the silicon carbide substrate are summarized. Al2O3-HfO2 eutectic EBC film is prepared by optical zone melting method on the silicon carbide substrate. At high temperature, a small amount of silicon carbide decomposed into silicon and carbon. The components of Al2O3 and HfO2 in molten phase also react with the free carbon. The Al2O3 phase reacts with free carbon and vapor species of AlO phase is formed. The composition of the molten phase becomes HfO2 rich from the eutectic composition. HfO2 phase also reacts with the free carbon and HfC phase is formed on the silicon carbide substrate; then a high density intermediate layer is formed. The adhesion between the intermediate layer and the substrate is excellent by an anchor effect. When the solidification process finished before all of HfO2 phase is reduced to HfC phase, HfC-HfO2 functionally graded layer is formed on the silicon carbide substrate and the Al2O3-HfO2 eutectic structure grows from the top of the intermediate layer.

  3. n-3PUFA and Holter-derived autonomic variables in patients with heart failure: data from the Gruppo Italiano per lo Studio della Sopravvivenza nell'Insufficienza Cardiaca (GISSI-HF) Holter substudy.

    Science.gov (United States)

    La Rovere, Maria Teresa; Staszewsky, Lidia; Barlera, Simona; Maestri, Roberto; Mezzani, Alessandro; Midi, Paolo; Marchioli, Roberto; Maggioni, Aldo P; Tognoni, Gianni; Tavazzi, Luigi; Latini, Roberto

    2013-02-01

    n-3 Polyunsaturated fatty acid (n-3PUFA) supplementation in the Gruppo Italiano per lo Studio della Sopravvivenza nell'Insufficienza Cardiaca (GISSI-HF) study reduced total mortality in patients with heart failure (HF), but the mechanism of action is still debated. The hypothesis of the present GISSI-HF substudy was that n-3PUFA may have beneficial effects on cardiac autonomic control. To evaluate the effect of 1 g/day of n-3PUFA vs placebo on heart rate variability variables, deceleration capacity, and turbulence slope. The GISSI-HF study enrolled patients with HF of any cause and severity. Twenty-four-hour (range 16-24 hours) Holter recordings were performed and analyzed in 388 patients at baseline, 3 months, and 12 months. Baseline characteristics were compared by using the χ(2) test, t test, or nonparametric Wilcoxon 2-sample test. Changes over time were tested by using the analysis of covariance adjusted by baseline values. At baseline, 36% of the patients were older than 70 years, 82% were men, 92% presented a left ventricular ejection fraction<40%, and 80% were in New York Heart Association class II. An increase in mean RR interval, standard deviation of all normal-to-normal RR intervals, very low frequency power (all P<.05), and turbulence slope (P = .05) was observed after 3 months in the n-3PUFA group compared to the placebo group, independently of the frequency of dietary fish consumption or beta-blocker treatment. These differences between study groups were no longer statistically significant at 12 months. A per-protocol analysis in patients compliant with study treatment showed similar results. n-3PUFA supplementation partially restored autonomic modulation in patients with chronic HF; this effect was maximal after 3 months of treatment. Copyright © 2013 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  4. Effects of Modified Precursor Solution on Microstructure of (Y,Yb)MnO3/HfO2/Si

    Science.gov (United States)

    Suzuki, Kazuyuki; Kato, Kazumi

    2007-10-01

    Ferroelectric/insulator/silicon structures were prepared using (Y,Yb)MnO3 films as ferroelectrics and HfO2 thin films as insulators through alkoxy-derived precursor solutions. The HfO2 solution was chemically modified in order to decrease the number of heating cycles required. The HfO2 films prepared using a partially hydrolyzed alkoxide solution had a uniform structure. From the results of measurements of the roughness level and refractive index of the HfO2 films, the partial hydrolysis of the HfO2 solution was found to be effective for the formation of a uniform microstructure in a thin insulator film. (Y,Yb)MnO3/HfO2/Si structures were constructed using the resultant HfO2 thin films prepared using the modified solutions.

  5. Effects of C and Hf concentration on phase relations and microstructure of a wrought powder-metallurgy superalloy

    Science.gov (United States)

    Miner, R. V., Jr.

    1977-01-01

    NASA IIB-11, a candidate alloy for advanced temperature turbine engine disks, and four modifications with varying C and Hf concentrations were produced from prealloyed powders. Several notable effects of C and Hf concentration in the alloys were observed. Both the amount of the gamma-prime phase and its solvus temperature increased with decreasing C, but only the gamma-prime solvus was affected by Hf, increasing with increasing Hf. Hf also promoted a cellular gamma-prime precipitation. Hf was, however, about equally distributed between gamma-prime and gamma. Hf and C both affected the carbides formed. Increasing both promoted formation of an MC relative to that of an M6C.

  6. The Modulation of Ionospheric Alfvén Resonator on Heating HF Waves and the Doppler Effect

    Institute of Scientific and Technical Information of China (English)

    Ni Bin-bin; Zhao Zheng-yu; Xie Shu-guo

    2003-01-01

    Abstract: The propagation of HF waves in IAR can produce many nonlinear effects, including the modulation effect of IAR on HF waves and the Doppler effect. To start with the dependence of the ionospheric electron temperature variaof the modulation effect and lucubrate possible reasons for the field can have an observable modulation effect on HF waves while its mechanism is quite different from that of Schumann resonant field on HF waves. The depth of modulation of IAR field, which directly inspires the formation of cross-spectrum between ULF waves and HF waves and results in spectral peaks at some gyro-frequencies of IAR. With respect to the Doppler effect during the propagation of HF waves in IAR, it is mainly caused by the motion of the high-speed flyer and the drifting electrons and the frequency shift from the phase variation of the reflected waves can be neglected when the frequency of HF incident wave is high enough.

  7. Hf diffusion in dilute Fe-free Zr(Nb) alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zou, H.; Hood, G.M.; Roy, J.A.; Schultz, R.J. [Atomic Energy of Canada Ltd., Chalk River, ON (Canada). Chalk River Nuclear Labs.; Jackman, J.A. [Canada Centre for Mineral and Energy Technology, Ottawa, ON (Canada)

    1995-04-01

    Hf diffusion coefficients D have been measured in the {alpha}-phase of the Fe-free binary alloys Zr-1.0 at.% Nb and Zr-2.5 at.% Nb in the temperature range 830-1100 K. The D values for the two alloys are essentially indistinguishable and little different from extant Hf diffusion coefficients measured in Fe-free polycrystalline {alpha}-Zr. The temperature dependence of D in the alloys is characteristic of intrinsic {alpha}-Zr bulk behaviour. The present hf D values are much lower than corresponding values measured in commercial Zr-2.5 Nb. The difference is attributable to the influence of solid-solution Fe. In addition, the absence of a strong enhancement of Hf diffusion in {alpha}-Zr by Nb suggests that intrinsic Nb diffusion in {alpha}-Zr may not be controlled by a normal vacancy mechanism. (author).

  8. HF183/BFDrev and HumM2 qPCR data

    Data.gov (United States)

    U.S. Environmental Protection Agency — Concentration estimates for HF183/BFDrev and HumM2 qPCR genetic markers in raw sewage collected from 54 geographic locations across the United States. This dataset...

  9. Phase Transformation and Thermal Stability of Aged Ti-Ni-Hf High Temperature Shape Memory Alloys

    Institute of Scientific and Technical Information of China (English)

    Xianglong MENG; Wei CAI; K.T.Lau; L.M.Zhou; Liancheng ZHAO

    2006-01-01

    The use of Ni-rich TiNiHf alloys as high temperature shape memory alloys(SMAs)through aging has been presented. For Ni-rich Ti80-xNixHf20 alloys, their phase transformation temperatures are averagely increased more than 100 K by aging at 823 K for 2 h. Especially for the alloys with Ni-content of 50.4 at. pct and 50.6 at. pct, their martensitic transformation start temperatures(Ms)are more than 473 K after aging. TEM observation confirmed that some fine particles precipitate from the matrix during aging. The aged Ni-rich TiNiHf SMAs show the better thermal stability of phase transformation temperatures than the solutiontreated TiNiHf alloys. The fine particles precipitated during aging should be responsible for the increase of phase transformation temperatures and its high stability.

  10. Luminescence and scintillation properties of Rb2HfCl6 crystals

    Science.gov (United States)

    Saeki, Keiichiro; Wakai, Yuki; Fujimoto, Yutaka; Koshimizu, Masanori; Yanagida, Takayuki; Nakauchi, Daisuke; Asai, Keisuke

    2016-11-01

    We developed a scintillator based on a Rb2HfCl6 crystal as a ternary halide crystal with intrinsic luminescence. In the photoluminescence spectra, two emission bands are observed at 383 and 434 nm. The 434 nm emission band for Rb2HfCl6 may be attributed to [HfCl6]2- complex ion or [ZrCl6]2- impurity, since the Rb2HfCl6 contained Zr as impurity at 0.62 mol %. The radioluminescence band is observed at 420 nm and can be attributed to the same origin as the photoluminescence band at 434 nm. The scintillation decay-time constants were 0.84 and 5.4 µs. The light yield was estimated to be 24,100 photons/MeV.

  11. Development of Hf(4+)-immobilized polydopamine-coated magnetic graphene for highly selective enrichment of phosphopeptides.

    Science.gov (United States)

    Lin, Haizhu; Deng, Chunhui

    2016-01-01

    In this work, we first designed and synthesized an IMAC material with Hf(4+) immobilized on polydopamine-coated magnetic graphene and applied it to phosphopeptides enrichment successfully. The newly prepared material gathered the advantages of large specific surface area of graphene, good hydrophilicity and biocompatibility of polydopamine and superparamagnetism of Fe3O4. We investigated the performance of Hf(4+)-immobilized polydopamine-coated magnetic graphene (denoted as magG@PDA-Hf(4+)) in phosphopeptides enrichment and the results showed high selectivity and sensitivity of the new material. Finally, we successfully applied magG@PDA-Hf(4+) to phosphopeptides enrichment from non-fat milk digests and human serum, further demonstrating excellent performance of this new material in phosphopeptides enrichment. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Intergrowth Structure in U- and Hf-Bearing Pyrochlore and Zirconolite: TEM Investigation

    Energy Technology Data Exchange (ETDEWEB)

    Xu, H; Wang, Y; Zhao, P; Bourcier, W L; Van Konynenburg, R; Shaw, H F

    2002-12-04

    Transmission electron microscopy results from a sintered ceramics with stoichiometry of Ca(U{sub 0.5}Ce{sub 0.25}Hf{sub 0.25})Ti{sub 2}O{sub 7} show the material contains both pyrochlore and zirconolite phases and structural intergrowth of zirconolite lamellae within pyrochlore. (001) plane of zirconolite is parallel to (111) plane of pyrochlore because of their structural similarities. The pyrochlore is relatively rich in U, Ce, and Ca with respect to the coexisting zirconolite. Average compositions for the coexisting pyrochlore and zirconolite produced by sintering at 1350 C are (Ca{sub 1.01}Ce{sub 0.13}{sup 3+}Ce{sub 0.19}{sup 4+}U{sub 0.52}Hf{sub 0.18})(Ti{sub 1.95}Hf{sub 0.05})O{sub 7} (with U/(U+Hf) (in the AB sites) = 0.74) and (Ca{sub 0.91}Ce{sub 0.09})(Ce{sub 0.08}{sup 3+}U{sub 0.26}Hf{sub 0.66}Ti{sub 0.01})Ti{sub 2.00}O{sub 7} (with U/(U+Hf) = 0.28) respectively. A single pyrochlore ((Ca,U,Hf){sub 2}Ti{sub 2}O{sub 7}) phase may be synthesized at 1350 C if the ratio of U/(U+Hf) is greater than 0.72, and a single zirconolite (Ca(Hf,U)Ti{sub 2}O{sub 7}) phase may be synthesized at 1350 C if the ratio of U/(U+Hf) is less than 0.28. An amorphous leached layer that is rich in Ti and Hf forms on the surface after the ceramics has been leached in pH 4 buffered solution. The thickness of the layer ranges from 5 nm to 15 nm. It is suggested that under these conditions, the leached layer functions as a protective layer, and reduces the leaching rate over time.

  13. Subduction Controls of Hf and Nd Isotopes in Lavas of the Aleutian Island Arc

    Energy Technology Data Exchange (ETDEWEB)

    Yogodzinski, Gene; Vervoort, Jeffery; Brown, Shaun Tyler; Gerseny, Megan

    2010-08-29

    The Hf and Nd isotopic compositions of 71 Quaternary lavas collected from locations along the full length of the Aleutian island arc are used to constrain the sources of Aleutian magmas and to provide insight into the geochemical behavior of Nd and Hf and related elements in the Aleutian subduction-magmatic system. Isotopic compositions of Aleutian lavas fall approximately at the center of, and form a trend parallel to, the terrestrial Hf-Nd isotopic array with {var_epsilon}{sub Hf} of +12.0 to +15.5 and {var_epsilon}{sub Nd} of +6.5 to +10.5. Basalts, andesites, and dacites within volcanic centers or in nearby volcanoes generally all have similar isotopic compositions, indicating that there is little measurable effect of crustal or other lithospheric assimilation within the volcanic plumbing systems of Aleutian volcanoes. Hafnium isotopic compositions have a clear pattern of along-arc increase that is continuous from the eastern-most locations near Cold Bay to Piip Seamount in the western-most part of the arc. This pattern is interpreted to reflect a westward decrease in the subducted sediment component present in Aleutian lavas, reflecting progressively lower rates of subduction westward as well as decreasing availability of trench sediment. Binary bulk mixing models (sediment + peridotite) demonstrate that 1-2% of the Hf in Aleutian lavas is derived from subducted sediment, indicating that Hf is mobilized out of the subducted sediment with an efficiency that is similar to that of Sr, Pb and Nd. Low published solubility for Hf and Nd in aqueous subduction fluids lead us to conclude that these elements are mobilized out of the subducted component and transferred to the mantle wedge as bulk sediment or as a silicate melt. Neodymium isotopes also generally increase from east to west, but the pattern is absent in the eastern third of the arc, where the sediment flux is high and increases from east to west, due to the presence of abundant terrigenous sediment in the

  14. Microstructure and Elevated Temperature Properties of a Refractory TaNbHfZrTi Alloy

    Science.gov (United States)

    2012-01-24

    alloy was prepared by vacuum arc melting of the equimolar mixtures of the corresponding elements. Titanium, zirconium, and hafnium were in the form of...AND ELEVATED TEMPERATURE PROPERTIES OF A REFRACTORY TaNbHfZrTi ALLOY (POSTPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER 5c. PROGRAM...6260-2. 14. ABSTRACT Compression properties of a refractory multicomponent alloy , Ta20Nb20Hf20Zr20Ti20, were determined in the temperature range

  15. High-reflectivity HfO2/SiO2 ultraviolet mirrors.

    Science.gov (United States)

    Torchio, Philippe; Gatto, Alexandre; Alvisi, Marco; Albrand, Gérard; Kaiser, Norbert; Amra, Claude

    2002-06-01

    High-reflectivity dense multilayer coatings were produced for the ultraviolet spectral region. Thin-film single layers and UV mirrors were deposited by ion plating and plasma ion-assisted deposition high-energetic technologies. Optical characterizations of HfO2 and SiO2 single layers are made. The optical constants obtained for these two materials are presented. HfO2 and SiO2 mirrors with a reflectance of approximately 99% near 250 nm are reported.

  16. Soft Magnetic Thin Films FeCoHfO for High-Frequency Noise Suppression Applications

    Institute of Scientific and Technical Information of China (English)

    LU Guang-Duo; ZHANG Huai-Wu; TANG Xiao-Li

    2010-01-01

    @@ A series of FeCoHfO films were fabricated by dc magnetron reactive sputtering at varying partial pressure of oxygen(Po2)from 0 to 11.7%,and the electrical and magnetic properties of films have been studied.It is shown that optimal Fe43.29 Co19.51 Hf7.49O29.71 films with desired properties can be obtained when the films were prepared under Po2 = 5.1%.

  17. Longitudinal Plasmoid in High-Speed Vortex Gas Flow Created by Capacity HF Discharge

    Science.gov (United States)

    2010-10-28

    instrumentation will be used in this Project to study plasma and gas flow parameters, including new shadow device with excimer KrF laser, MW...vortex decay (attenuation) by HF plasma. The additional experiments with small helium jet injection prove the conclusion about vortex attenuation by a...equilibrium HF plasma. Plasma and airflow parameters are measured by different diagnostic instrumentation including shadow optical device with excimer

  18. Electron scattering cross sections with HF, OH, NH and CH molecules

    Energy Technology Data Exchange (ETDEWEB)

    Joshipura, K.N. [Sardar Patel Univ., Vallabh Vidyanagar (India). Dept. of Physics; Vinodkumar, M. [Sardar Patel Univ., Vallabh Vidyanagar (India). Dept. of Physics

    1997-01-20

    Total cross sections including elastic scattering, electronic excitation-ionisation and the dipole rotational excitation are calculated for electron impact on HF, OH, NH, and CH molecules. The additivity rules as well as single-centre expansion are employed for this purpose. A comparison was possible for the e-HF system only. Our results are expected to be good at intermediate to high energies (>50 eV). (orig.).

  19. Incremental Prognostic Power of Novel Biomarkers (Growth-Differentiation Factor-15, High-Sensitivity C-Reactive Protein, Galectin-3, and High-Sensitivity Troponin-T) in Patients With Advanced Chronic Heart Failure

    NARCIS (Netherlands)

    Lok, Dirk J.; Klip, IJsbrand T.; Lok, Sjoukje I.; de la Porte, Pieta W. Bruggink-Andre; Badings, Erik; van Wijngaarden, Jan; Voors, Adriaan A.; de Boer, Rudolf A.; van Veldhuisen, Dirk J.; van der Meer, Peter

    2013-01-01

    Elevated natriuretic peptides provide strong prognostic information in patients with heart failure (HF). The role of novel biomarkers in HF needs to be established. Our objective was to evaluate the prognostic power of novel biomarkers, incremental to the N-terminal portion of the natriuretic peptid

  20. [Testing aerobic power].

    Science.gov (United States)

    Lehance, C; Bury, T

    2008-01-01

    Maximal oxygen uptake (VO2 max) is regarded by some as the best single measurement of aerobic fitness. An other major determinant of successful endurance performance is the percentage of VO2 max that an athlete can maintain for a prolonged period. It is related to the lactate threshold. Two other factors also appear to be important for endurance activities as high economy of effort, or low VO2 value for the same rate of work; high percentage of ST muscle fibers. In the laboratory, the usual measurements of aerobic power include the determination of maximum oxygen consumption and the identification of lactate threshold. Testing aerobic power can help determine the type of aerobic training that should be emphasized.

  1. Ultrathin Hf0.5Zr0.5O2 Ferroelectric Films on Si.

    Science.gov (United States)

    Chernikova, Anna; Kozodaev, Maksim; Markeev, Andrei; Negrov, Dmitrii; Spiridonov, Maksim; Zarubin, Sergei; Bak, Ohheum; Buragohain, Pratyush; Lu, Haidong; Suvorova, Elena; Gruverman, Alexei; Zenkevich, Andrei

    2016-03-23

    Because of their immense scalability and manufacturability potential, the HfO2-based ferroelectric films attract significant attention as strong candidates for application in ferroelectric memories and related electronic devices. Here, we report the ferroelectric behavior of ultrathin Hf0.5Zr0.5O2 films, with the thickness of just 2.5 nm, which makes them suitable for use in ferroelectric tunnel junctions, thereby further expanding the area of their practical application. Transmission electron microscopy and electron diffraction analysis of the films grown on highly doped Si substrates confirms formation of the fully crystalline non-centrosymmetric orthorhombic phase responsible for ferroelectricity in Hf0.5Zr0.5O2. Piezoresponse force microscopy and pulsed switching testing performed on the deposited top TiN electrodes provide further evidence of the ferroelectric behavior of the Hf0.5Zr0.5O2 films. The electronic band lineup at the top TiN/Hf0.5Zr0.5O2 interface and band bending at the adjacent n(+)-Si bottom layer attributed to the polarization charges in Hf0.5Zr0.5O2 have been determined using in situ X-ray photoelectron spectroscopy analysis. The obtained results represent a significant step toward the experimental implementation of Si-based ferroelectric tunnel junctions.

  2. Superconductivity in HfTe5 across weak to strong topological insulator transition induced via pressures.

    Science.gov (United States)

    Liu, Y; Long, Y J; Zhao, L X; Nie, S M; Zhang, S J; Weng, Y X; Jin, M L; Li, W M; Liu, Q Q; Long, Y W; Yu, R C; Gu, C Z; Sun, F; Yang, W G; Mao, H K; Feng, X L; Li, Q; Zheng, W T; Weng, H M; Dai, X; Fang, Z; Chen, G F; Jin, C Q

    2017-03-16

    Recently, theoretical studies show that layered HfTe5 is at the boundary of weak &strong topological insulator (TI) and might crossover to a Dirac semimetal state by changing lattice parameters. The topological properties of 3D stacked HfTe5 are expected hence to be sensitive to pressures tuning. Here, we report pressure induced phase evolution in both electronic &crystal structures for HfTe5 with a culmination of pressure induced superconductivity. Our experiments indicated that the temperature for anomaly resistance peak (Tp) due to Lifshitz transition decreases first before climbs up to a maximum with pressure while the Tp minimum corresponds to the transition from a weak TI to strong TI. The HfTe5 crystal becomes superconductive above ~5.5 GPa where the Tp reaches maximum. The highest superconducting transition temperature (Tc) around 5 K was achieved at 20 GPa. Crystal structure studies indicate that HfTe5 transforms from a Cmcm phase across a monoclinic C2/m phase then to a P-1 phase with increasing pressure. Based on transport, structure studies a comprehensive phase diagram of HfTe5 is constructed as function of pressure. The work provides valuable experimental insights into the evolution on how to proceed from a weak TI precursor across a strong TI to superconductors.

  3. Resistive switching characteristics of Pt/TaOx/HfNx structure and its performance improvement

    Directory of Open Access Journals (Sweden)

    Qigang Zhou

    2013-03-01

    Full Text Available The refractory transition metal nitride (TMN film Hafnium nitride (HfNx was successfully prepared on silicon-based substrates as bottom electrodes for resistive random access memory (RRAM cells in Pt (top/metal oxide/ HfNx (bottom sandwich structure. The reproducible resistive switching (RS characteristics of the memory cells were studied systematically for RRAM applications. The advantages of adopting HfNx instead of Pt as bottom electrode material were demonstrated, including the improvement of the low resistive state value, the RS endurance and the uniformity of RS parameters. The composition and chemical bonding states of the prepared HfNx was analyzed by X-ray photoelectron spectroscopy (XPS technique. The nitrogen content in the HfNx and the Gibbs free energy of the corresponding metal oxide formation has great influences on the RS properties. The oxygen reservoir ability and diffusion barrier effect of the HfNx play a key role in the RS performance improvement of the RRAM devices.

  4. First-principles calculations of adhesion, bonding and magnetism of the Fe/HfC interface

    Energy Technology Data Exchange (ETDEWEB)

    Si Abdelkader, H., E-mail: hayet.siabdelkader@mail.univ-tlemcen.dz [Laboratoire d' Etude et Prediction des Materiaux, Unite de Recherche Materiaux et Energies Renouvelables. LEPM-URMER. Universite de Tlemcen, Tlemcen 13000 (Algeria); Faraoun, H.I. [Laboratoire d' Etude et Prediction des Materiaux, Unite de Recherche Materiaux et Energies Renouvelables. LEPM-URMER. Universite de Tlemcen, Tlemcen 13000 (Algeria)

    2012-12-15

    First-principles plane-wave pseudopotential calculations of the adhesion, bonding and magnetism of the interface between the ferromagnetic bcc Fe and non-magnetic HfC are performed. The work of adhesion for C- and Hf-site Fe/HfC interfaces is calculated. High adhesion at C-site interface is found and Fe-C polar covalent bonds are formed across the interface. The magnetic moments of Fe atoms at interface are increased in both interfaces. The effect of the magnetism on the electronic structure of Fe/HfC interface is also investigated. It is shown that the change in band of majority-spin leads to enhance the magnetic moment of Fe. - Highlights: Black-Right-Pointing-Pointer Adhesion, electronic and magnetism of Fe(110)/HfC(100) interface are studied. Black-Right-Pointing-Pointer High adhesion at C-site interface is found and Fe-C polar covalent bonds are formed across the interface. Black-Right-Pointing-Pointer The magnetic moments of interfacial Fe atoms are increased in both C-site and Hf-site interfaces.

  5. Hf, Zr, and REE partition coefficients between ilmenite and liquid - Implications for lunar petrogenesis

    Science.gov (United States)

    Nakamura, Y.; Fujimaki, H.; Nakamura, N.; Tatsumoto, M.; Mckay, G. A.

    1986-01-01

    Partition coefficients (D) between ilmenite and coexisting liquid were determined under near-lunar conditions for Hf, Zr, and REE. Through isotope dilution analysis, ilmenite D values of 0.41 and 0.33 were obtained for Hf and Zr respectively, values significantly lower than those of ilmenite from a kimberlite megacryst. Partition coefficients of REE for the synthesized ilmenite are slightly smaller than those of ilmenite from the kimberlite megacryst, and the lunar (Lu) partition coefficient is 0.056. These results suggest that ilmenite was significant in the lunar-Hf evolution of lunar mare basalts. Using lunar and Hf D values for ilmenite, the Lu-Hf evolution of lunar cumulates and the coexisting magma was examined for various crystallization sequences. The Lu-Hf variation trend of most high-Ti mare basalts is explained by a small degree of partial cumulate melting, though a higher degree is required to explain the variation of very low-Ti basalts, green glass, and Apollo 12 low-Ti basalts. Apollo 15 low-Ti basalts may require chromite crystallization as well.

  6. Partition coefficients of Hf, Zr, and REE between phenocrysts and groundmasses

    Science.gov (United States)

    Fujimaki, H.; Tatsumoto, M.; Aoki, K.-I.

    1984-01-01

    Partition coefficients of Hf, Zr, and REE between olivine, orthopyroxene, clinopyroxene, plagioclase, garnet, amphibole, ilmenite, phlogopite, and liquid are presented. Samples consist of megacrysts in kimberlite, phenocrysts in alkaline basalts, tholeiitic basalts and andesitic to dacitic rocks, and synthetic garnet and clinopyroxene in Hawaiian tholeiites. The Hf-Lu and Zr-Lu elemental fractionations are as large as the Lu-Sm or Lu-Nd fractionation. The Hf and Zr partition coefficients between mafic phenocrysts and liquids are smaller than the Lu partition coefficients, but are similar to the Nd or Sm partition coefficients. The Hf and Zr partition coefficients between ilmenite, phlogopite, and liquid are larger than the Lu partition coefficients for these minerals and their corresponding liquids. The Hf-Zr elemental fractionation does not occur except for extreme fractionation involving Zr-minerals and extremely low fO2. These data have an important bearing on chronological and petrogenetic tracer studies involving the Lu-Hf isotopic system.

  7. Ergonomics action research II: a framework for integrating HF into work system design.

    Science.gov (United States)

    Neumann, W P; Village, J

    2012-01-01

    This paper presents a conceptual framework that can support efforts to integrate human factors (HF) into the work system design process, where improved and cost-effective application of HF is possible. The framework advocates strategies of broad stakeholder participation, linking of performance and health goals, and process focussed change tools that can help practitioners engage in improvements to embed HF into a firm's work system design process. Recommended tools include business process mapping of the design process, implementing design criteria, using cognitive mapping to connect to managers' strategic goals, tactical use of training and adopting virtual HF (VHF) tools to support the integration effort. Consistent with organisational change research, the framework provides guidance but does not suggest a strict set of steps. This allows more adaptability for the practitioner who must navigate within a particular organisational context to secure support for embedding HF into the design process for improved operator wellbeing and system performance. There has been little scientific literature about how a practitioner might integrate HF into a company's work system design process. This paper proposes a framework for this effort by presenting a coherent conceptual framework, process tools, design tools and procedural advice that can be adapted for a target organisation.

  8. Influence of cointercalated HF on the electrochemical behavior of highly fluorinated graphite

    Science.gov (United States)

    Nakajima, Tsuyoshi; Gupta, Vinay; Ohzawa, Yoshimi; Groult, Henri; Mazej, Zoran; Žemva, Boris

    Highly fluorinated graphite was prepared at room temperature using high oxidation state transition metal complex fluoride (K 2PdF 6, K 2MnF 6, K 2NiF 6 or KAgF 4) and elemental fluorine under pressure ((5.9-11.8) ×10 5 Pa) in anhydrous liquid HF (aHF). The composition of the fluorinated graphite samples ranged from C 1.1F to C 1.9F containing small amounts of HF. IR absorption spectra revealed that stage 1 phase of C xF contained several different phases with planar (sp 2) and puckered (sp 3) graphene layers. Electrochemical discharge of the fluorinated graphite showed that profile of discharge potential and discharge capacity varied depending on the amount of cointercalated HF. The C xF samples with less amounts of HF and HF 2δ- had relatively flat discharge potentials and large discharge capacities. The discharge capacity reached 500-600 mAh/g in 1 mol/dm 3 LiClO 4-propylene carbonate solution at 25 °C. Chemical diffusion coefficients of Li + ion in the intermediate discharge products were (4.4-13) ×10 -12 cm 2/s from impedance measurement.

  9. A new wideband HF technique for MHz-bandwidth spread-spectrum radio communications

    Science.gov (United States)

    Perry, B. D.

    1983-09-01

    The one-way results are seen as demonstrating that equalized MHz-bandwidth skywave HF channels can be achieved using long-range one-hop F-layer propagation paths. It has thus become possible to use direct-sequence pseudo-noise or coherent fast-frequency-hop signaling at HF with processing gains of several orders of magnitude for teletype data rates. Possibilities are seen for using the spread spectrum in covert and/or jam-resistant communications. What is more, the equalized wideband HF channel is not subject to the fading caused by multiple propagation modes; as a consequence, it is substantially more reliable than the traditional narrow-band HF channel. Conversely, reliability comparable to traditional HF can be attained at greatly reduced signal margins. Since the time stability of the wideband HF channel is of the order of 10 s, very little channel-transmission time is needed for initializing and maintaining the equalizer. It is noted that probe signals similar to the channel-measuring waveform described here or spread-spectrum training sequences at the beginning of each message are adequate. Results from the 1982 two-way experimentation show that N(omega) is not reciprocal between terminals 2000 km apart.

  10. Low Threshold Voltage and High Mobility N-Channel Metal-Oxide-Semiconductor Field-Effect Transistor Using Hf-Si/HfO2 Gate Stack Fabricated by Gate-Last Process

    Science.gov (United States)

    Ando, Takashi; Hirano, Tomoyuki; Tai, Kaori; Yamaguchi, Shinpei; Yoshida, Shinichi; Iwamoto, Hayato; Kadomura, Shingo; Watanabe, Heiji

    2010-01-01

    Systematic characterization of Hf-Si/HfO2 gate stacks revealed two mobility degradation modes. One is carrier scattering by fixed charges and/or trapped charges induced by the crystallization in the thick HfO2 case (inversion oxide thickness, Tinv> 1.6 nm). The other is the Hf penetration into the interfacial layer with the Si substrate in the thin HfO2 case (Tinv< 1.6 nm) for the Hf-rich electrode. It was demonstrated that careful optimization of the HfO2 thickness and the Hf-Si composition can suppress both modes. As a result, a high electron mobility equivalent to that of n+polycrystalline silicon (poly-Si)/SiO2 (248 cm2 V-1 s-1 at Eeff=1 MV/cm) was obtained at Tinv of 1.47 nm. Moreover, the effective work function of the optimized Hf-Si/HfO2 gate stack is located within 50 mV from the Si band edge (Ec). An extremely high Ion of 1165 µA/µm (at Ioff = 81 nA/µm) at Vdd=1.0 V was demonstrated for a 45 nm gate n-channel metal-oxide-semiconductor field-effect transistor (n-MOSFET) without strain enhanced technology.

  11. Partial Oxidation of Methane with Sol-Gel Fe/Hf/YSZ Catalyst in Dielectric Barrier Discharge: Catalyst Activation by Plasma

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A 1% Fe-30% Hf over yttria-stabilized zirconia catalyst in combination with novel plasma-assisted activation techniques for a direct partial oxidation of methane to methanol was tested using dielectric barrier discharge plasma at ambient temperature and atmospheric pressure. However, instead of methanol, the reaction products were dominated by H2,CO, CO2, C2, and H2O. A catalytically activated plasma process increased the production of methanol compared with a noncatalytic plasma process. The maximum selectivity of methanol production was achieved using a catalyst that was treated at higher applied power.

  12. First observations of electron gyro-harmonic effects under X-mode HF pumping the high latitude ionospheric F-region

    Science.gov (United States)

    Blagoveshchenskaya, N. F.; Borisova, T. D.; Kalishin, A. S.; Yeoman, T. K.; Häggström, I.

    2017-03-01

    We provide the first experimental evidence of the sensitivity of phenomena induced by extraordinary (X-mode) polarized HF high power radio waves to pump frequency stepping across the fifth electron gyro-harmonic (5fce) from below to above. The results were obtained at the EISCAT (European Incoherent Scatter Scientific Association) HF heater facility near Tromsø under effective radiated powers of 456-715 MW, when the HF pump wave was transmitted into the magnetic zenith. We have analyzed the behavior and intensities of various spectral lines in the narrowband stimulated electromagnetic emission (SEE) spectra observed far from the heater, HF-enhanced plasma and ion lines (HFPL and HFIL) from EISCAT UHF incoherent scatter radar spectra, and artificial field-aligned irregularities from CUTLASS (Co-operative UK Twin Located Auroral Sounding System) observations, depending on the frequency offset of the pump field relative to the 5fce. At pump frequencies below 5fce the narrowband SEE spectra exhibited very intense so-called stimulated ion Bernstein scatter (SIBS), accompanied by other spectral components, associated with stimulated Brillouin scatter (SBS), which are greatly suppressed and disappeared in the vicinity of 5fce and did not reappear at fH>5fce. As the pump frequency reached 5fce, the abrupt enhancements of the HFPL and HFIL power, the appearance of cascade lines in the plasma line spectra, and the onset of increasing CUTLASS backscatter power occurred. That is opposite to the ordinary mode (O-mode) effects in the vicinity of 5fce. The X-mode pumping at frequencies below and in the vicinity of the fifth electron gyro-harmonic clearly demonstrated an ascending altitude of generation of induced plasma and ion lines from the initial interaction height, whereas for O-mode heating the region of interaction descended. The observations are consistent with the coexistence of the electron acceleration along and across the geomagnetic field at fH<5fce, while only very

  13. Investigating the influence of infill percentage on the mechanical properties of fused deposition modelled ABS parts

    Directory of Open Access Journals (Sweden)

    Kenny Álvarez

    2016-09-01

    Full Text Available 3D printing is a manufacturing process that is usually used for modeling and prototyping. One of the most popular printing techniques is fused deposition modeling (FDM, which is based on adding melted material layer by layer. Although FDM has several advantages with respect to other manufacturing materials, there are several problems that have to be faced. When setting the printing options, several parameters have to be taken into account, such as temperature, speed, infill percentage, etc. Selecting these parameters is often a great challenge for the user, and is generally solved by experience without considering the influence of variations in the parameters on the mechanical properties of the printed parts.This article analyzes the influence of the infill percentage on the mechanical properties of ABS (Acrylonitrile Butadiene Styrene printed parts. In order to characterize this influence, test specimens for tensile strength and Charpy tests were printed with a Makerbot Replicator 2X printer, in which the infill percentage was varied but the rest of the printing parameters were kept constant. Three different results were analyzed for these tests: tensile strength, impact resistance, and effective printing time. Results showed that the maximum tensile force (1438N and tensile stress (34,57MPa were obtained by using 100% infill. The maximum impact resistance, 1,55J, was also obtained with 100% infill. In terms of effective printing time, results showed that printing with an infill range between 50% and 98% is not recommended, since the effective printing time is higher than with a 100% infill and the tensile strength and impact resistance are smaller. In addition, in comparing the results of our analysis with results from other authors, it can be concluded that the printer type and plastic roll significantly influence the mechanical properties of ABS parts.

  14. VARIOUS FACTORS AFFECTING DRESSING PERCENTAGE OF COMMERCIALLY CULTURED CYPRINID FISH IN CARP FISH PONDS IN SERBIA

    Directory of Open Access Journals (Sweden)

    Todor Marković

    2012-12-01

    Full Text Available The aim of this study was to determine the yield carcass of all categories of cyprinid fish reared in ponds in Serbia. Samples of two and three-year old carp, two-year old silver carp and grass carp were taken in the winter from a pond where the production is organized in a semi­intensive system. The three­year old carp was sampled from two ponds. In one case, it fed on barley, maize and wheat in the following proportions 40:30:30, while in the second case it fed on complete diet mixtures. Also, the samples of two­year old carp were taken from ponds where they fed on complete feed mixture. Dressing percentage was the most favourable in common carp (67%, followed by silver carp (62%, and it was the least in grass carp (60% (p<0.01. The best yield (66% was obtained in two-year old carp, followed by one-year old carp (64%, and the worst yield was determined in three-year old carp (58% (p<0.01. Carcasses yield was better in two-year old carp fed on pelleted feed (68% than in carp of the same age fed on grains (66% (p<0.01. The values of dressing percentage measured in three-year old carp reared in the semi-intensive system was 56%, and 59% in three-year old carp fed on pelleted complete feed mixture. Fish species, age, system of husbandry and diet showed a significant effect on carcasses yield. The highest dressing percentage and weight of fillets was noted in two-year old carp fed on complete feed, and it was a result of lower weight of internal organs and associated fat. The obtained results may be helpful in creating the best strategy for the selection of raw fish for fish manufacturing.

  15. Mitochondrial DNA deletion percentage in sun exposed and non sun exposed skin.

    Science.gov (United States)

    Powers, Julia M; Murphy, Gillian; Ralph, Nikki; O'Gorman, Susan M; Murphy, James E J

    2016-12-01

    The percentages of mitochondrial genomes carrying the mtDNA(3895) and the mtDNA(4977) (common) deletion were quantified in sun exposed and non sun exposed skin biopsies, for five cohorts of patients varying either in sun exposure profile, age or skin cancer status. Non-melanoma skin cancer diagnoses are rising in Ireland and worldwide [12] but most risk prediction is based on subjective visual estimations of sun exposure history. A quantitative objective test for pre-neoplastic markers may result in better adherence to sun protective behaviours. Mitochondrial DNA (mtDNA) is known to be subject to the loss of a significant proportion of specific sections of genetic code due to exposure to ultraviolet light in sunlight. Although one such deletion has been deemed more sensitive, another, called the mtDNA(4977) or common deletion, has proved to be a more useful indicator of possible risk in this study. Quantitative molecular analysis was carried out to determine the percentage of genomes carrying the deletion using non sun exposed and sun exposed skin biopsies in cohorts of patients with high or low sun exposure profiles and two high exposure groups undergoing treatment for NMSC. Results indicate that mtDNA deletions correlate to sun exposure; in groups with high sun exposure habits a significant increase in deletion number in exposed over non sun exposed skin occurred. An increase in deletion percentage was also seen in older cohorts compared to the younger group. The mtDNA(3895) deletion was detected in small amounts in exposed skin of many patients, the mtDNA(4977) common deletion, although present to some extent in non sun exposed skin, is suggested to be the more reliable and easily detected marker. In all cohorts except the younger group with relatively lower sun exposure, the mtDNA(4977) deletion was more frequent in sun exposed skin samples compared to non-sun exposed skin.

  16. The Percentage of Amplitude Decrease Warning Criteria for Transcranial MEP Monitoring.

    Science.gov (United States)

    Journée, Henricus L; Berends, Hanneke I; Kruyt, Moyo C

    2017-01-01

    Muscle motor evoked potentials (MEPs) from transcranial electrical stimulation (TES) became a standard technique for monitoring the motor functions of the brain and spinal cord at risk during spinal and brain surgery. However, a wide range of criteria based on the percentage of amplitude decrease is used in practice. A survey of the current literature on clinical outcome parameters reveals a variety of percentages in a range of 30% to 100% (50% to 100% spinal procedures) with no consensus. The interpretation of muscle MEPs is hampered by their sensitivity to many interfering factors. Trial-to-trial MEP variations may partly be reduced by controllable parameters of which TES parameters are in the hands of the neuromonitorist. We propose an operational model based on basic neurophysiologic knowledge to interpret the characteristics of MEP-TES voltage curves and predict the influences of the location on the sigmoid voltage curve on spontaneous MEP-variations and influences of factors affecting the voltage curve. The model predicts a correlation between the slope, expressed by a gain, and variations of muscle MEP amplitudes. This complies with two case examples. The limited specificity/sensitivity of warning criteria based on the percentage of amplitude reduction can possibly be improved by developing standards for set-up procedures of TES paradigms. These procedures include strategies for desensitizing MEPs for variations of controllable parameters. The TES voltage or current is a feasible controlling parameter and should be related to the motor threshold and the onset of the supramaximal level being landmarks of MEP-voltage functions. These parameters may offer a valuable addition to multicenter outcome studies.

  17. Low modulus Ti–Nb–Hf alloy for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    González, M., E-mail: Marta.Gonzalez.Colominas@upc.edu [Department of Materials Science and Metallurgy, Universitat Politècnica de Catalunya (UPC), Avda. Diagonal 647, 08028 Barcelona (Spain); Materials Science, Elisava Escola Superior de Disseny i Enginyeria de Barcelona, La Rambla 30-32, 08002 Barcelona (Spain); Peña, J. [Department of Materials Science and Metallurgy, Universitat Politècnica de Catalunya (UPC), Avda. Diagonal 647, 08028 Barcelona (Spain); Materials Science, Elisava Escola Superior de Disseny i Enginyeria de Barcelona, La Rambla 30-32, 08002 Barcelona (Spain); Gil, F.J.; Manero, J.M. [Department of Materials Science and Metallurgy, Universitat Politècnica de Catalunya (UPC), Avda. Diagonal 647, 08028 Barcelona (Spain); Ciber-BBN (Spain)

    2014-09-01

    β-Type titanium alloys with a low elastic modulus are a potential strategy to reduce stress shielding effect and to enhance bone remodeling in implants used to substitute failed hard tissue. For biomaterial application, investigation on the mechanical behavior, the corrosion resistance and the cell response is required. The new Ti25Nb16Hf alloy was studied before and after 95% cold rolling (95% C.R.). The mechanical properties were determined by tensile testing and its corrosion behavior was analyzed by potentiostatic equipment in Hank's solution at 37 °C. The cell response was studied by means of cytotoxicity evaluation, cell adhesion and proliferation measurements. The stress–strain curves showed the lowest elastic modulus (42 GPa) in the cold worked alloy and high tensile strength, similar to that of Ti6Al4V. The new alloy exhibited better corrosion resistance in terms of open circuit potential (E{sub OCP}), but was similar in terms of corrosion current density (i{sub CORR}) compared to Ti grade II. Cytotoxicity studies revealed that the chemical composition of the alloy does not induce cytotoxic activity. Cell studies in the new alloy showed a lower adhesion and a higher proliferation compared to Ti grade II presenting, therefore, mechanical features similar to those of human cortical bone and, simultaneously, a good cell response. - Highlights: • Presents low elastic modulus and high strength and elastic deformability. • Exhibits good biocompatibility in terms of cytotoxicity and cell response. • Corrosion resistance of this alloy is good, similar to that of Ti grade II. • Potential candidate for implants used to substitute failed hard tissue.

  18. The Analysis of Part-Time Jobs towards Percentage and Attitude among College Students

    Institute of Scientific and Technical Information of China (English)

    王俊鹏

    2016-01-01

    Nowadays taking a part-time job during free time has become a trend among college students,according to the Bureau of Labor Statistic in China,working part- time job is defined as a previous experience of getting an excellent position within a specific industry in the future.There are many kinds of reasons that must be taken into consideration. In today's world, more and more college students choose a part-time job because they are almost being asked to be financially independent.At the same time,part-time job employment in China involves a comprehensive percentage and attitude.

  19. Interstitial solid solution Hf{sub 5}Ga{sub x}Sn{sub 3} (x = 0-1)

    Energy Technology Data Exchange (ETDEWEB)

    Voznyak, I., E-mail: iravoznyak@gmail.com [Department of Inorganic Chemistry, Ivan Franko National University of Lviv, Kyryla i Mefodiya St. 6, 79005 Lviv (Ukraine); Tokaychuk, Ya. [Department of Inorganic Chemistry, Ivan Franko National University of Lviv, Kyryla i Mefodiya St. 6, 79005 Lviv (Ukraine); Hlukhyy, V.; Faessler, T.F. [Department of Chemistry, Technische Universitaet Muenchen, Lichtenbergstr. 4, 85747 Garching (Germany); Gladyshevskii, R. [Department of Inorganic Chemistry, Ivan Franko National University of Lviv, Kyryla i Mefodiya St. 6, 79005 Lviv (Ukraine)

    2012-01-25

    Highlights: Black-Right-Pointing-Pointer Formation of an interstitial solid solution Hf{sub 5}Ga{sub x}Sn{sub 3} (x = 0-1) based on the binary compound Hf{sub 5}Sn{sub 3} was established at 600 Degree-Sign C. Black-Right-Pointing-Pointer The Ga atoms occupy [Hf{sub 6}] octahedral interstices (Wyckoff position 2b) up to the composition Hf{sub 5}GaSn{sub 3}, which represents a Hf{sub 5}CuSn{sub 3}-type structure (ordered derivative of Ti{sub 5}Ga{sub 4}). Black-Right-Pointing-Pointer The cell parameters and cell volume increase with increasing gallium content. Black-Right-Pointing-Pointer The coordination number of the hafnium atoms in Wyckoff position 6g is reduced from 15 (Hf1Sn{sub 5}Hf{sub 10} for Hf{sub 5}Sn{sub 3}) to 11 (Hf1Sn{sub 5}Ga{sub 2}Hf{sub 4} for Hf{sub 5}GaSn{sub 3}). - Abstract: Formation of an interstitial solid solution Hf{sub 5}Ga{sub x}Sn{sub 3} (x = 0-1) based on the binary compound Hf{sub 5}Sn{sub 3} (structure type Mn{sub 5}Si{sub 3}, Pearson symbol hP16, space group P6{sub 3}/mcm, a = 8.36562(6), c = 5.70775(4) Angstrom-Sign from X-ray powder diffraction) was established at 600 Degree-Sign C. The crystal structure (structure type Hf{sub 5}CuSn{sub 3}, ordered derivative of Ti{sub 5}Ga{sub 4}, hP18, P6{sub 3}/mcm) was refined on X-ray single-crystal diffraction data for three compositions: Hf{sub 5}Ga{sub 0.16(3)}Sn{sub 3} (a = 8.3288(12), c = 5.6988(11) Angstrom-Sign ), Hf{sub 5}Ga{sub 0.53(2)}Sn{sub 3} (a = 8.4205(12), c = 5.7655(12) Angstrom-Sign ) and Hf{sub 5}GaSn{sub 3} (a = 8.5564(12), c = 5.7859(12) Angstrom-Sign ). The Ga atoms occupy Wyckoff position 2b at the centres of Hf{sub 6} octahedral interstices.

  20. Synthesis of metallic glasses and metallic glass based composites in the Cu-Mo-Hf system by ion beam mixing

    Institute of Scientific and Technical Information of China (English)

    BAI Xue; WANG TongLe; CUI YuanYuan; DING Ning; LI JiaHao; LIU BaiXin

    2012-01-01

    Single-phase and dual-phase metallic glasses as well as metallic glass based composites were synthesized in the Cu-Mo-Hf ternary metal system by 200 keV xenon ion beam mixing of far-from-equilibrium.It was found that Mo-Hf-based and Cu-Mo-based single-phase metallic glasses could be obtained at compositions around Cu17Mo20Hf63 and Cu34Mo57Hf9,respectively.Interestingly,at the nearly equal-atomic stoichiometry of Cu38Mo31Hf31,a dual-phase Cu-Mo-Hf metallic glass,consisting both of the Mo-Hf-based and Cu-Mo-based phases,was first obtained at relatively low irradiation doses ranging from (1-5)×1015 Xe+/cm2,and a single-phase metallic glass was eventually obtained at a dose of 7×1015 Xe+/cm2.In addition,two glass-based composites were obtained at the compositions of Cu14Mo62Hf24 and Cu77Mo14Hf9,and they consisted of the Mo-Hf based and Cu-Mo based metallic glasses,dissolved with some uniformly distributed BCC Mo-based and FCC Cu-based crystalline solid solutions,respectively.The formation mechanism of the above described non-equilibrium alloy phases was also discussed in terms of the atomic collision theory.