PurposeTo describe ocular findings for a 34-year-old man with chronic solar retinopathy using high-speedultrahigh-resolution (UHR) optical coherence tomography (OCT).Full Text Available
A railgun has an armature driven between two rail-like conductors. In other words, it is a linear drive device system that drives airframes by using the Lorentz`s force. The system is expected as a next-generation high-speed transport means, or as a means to create such ultimate fields as ultra-high pressures, ultra-high temperatures, and ultra-ferromagnetic fields. This paper is a report on investigations on the relevant technological trends as surveyed by the investigation committee at the Institute of Electrical Engineers of Japan using research reports published inside and outside the country. The reported themes cover explanations from the construction to the pulse power supply that forms the core of the technology, problems in switching, recent status of research and development, and to application fields. Compatibility in the high-level electrical and mechanical performances demanded in the railgun is not as easy as ...
Protein motions on all timescales faster than molecular tumbling are encoded in the spectral density. The dissection of complex protein dynamics is typically performed using relaxation rates determined at high and ultra-high field. Here we expand this range of the spectral density to low fields through field cycling using the nucleocapsid protein of the SARS coronavirus as a model system. The field-cycling approach enables site-specific measurements of R{sub 1} at low fields with the sensitivity and resolution of a high-field magnet. These data, together with high-field relaxation and heteronuclear NOE, provide evidence for correlated rigid-body motions of the entire {beta}-hairpin, and corresponding motions of adjacent loops with a time constant of 0.8 ns (mesodynamics). MD simulations substantiate these findings and provide direct verification of the time scale and collective nature of these motions.
Various characteristics of F stars are described. The spectra of F stars are analyzed, and it is determined that the spectral types are based on ionization levels. The CNO cycle and rotation speeds of the stars are examined. The period-luminosity relation of pulsators is studied, and specific examples of unstable pulsators are presented.
The B-Factory which is constructed by National Laboratory for High Energy Physics is the device for elucidating the breakdown of symmetry of matter and antimatter by studying the behavior of B mesons which are generated in large quantity when the electrons and the positrons which are accelerated to light velocity level are collided. In order to maintain electron beam-positron beam bunch circling the ring at light velocity stably, the instability of the coupled bunch must be overcome. For this purpose, the ultrahighspeed beam position digital feedback control system was developed. This system is composed of the high speed input-output substrate using GaAs LSI, the feedback computation substrate using complementary metal oxide semiconductor and the memory mounted on it, and the real time operation device. The development of both substrates and their functions are explained. The real time data collection and the change of ...
The Segmented Rail Phased Induction Motor (SERAPHIM) is a compact, pulsed linear induction motor (LIM) offering a unique capability for very high speed train propulsion. It uses technology developed for the Sandia coilgun, an electromagnetic launcher designed to accelerate projectiles to several kilometers per second. Both aluminum cylinders and plates were accelerated to a kilometer per second (Mach 3) by passing through a sequence of coils which were energized at the appropriate time. Although this technology was developed for ultra-high velocity, it can be readily adapted to train propulsion for which, at sea level, the power required to overcome air resistance limits the operational speed to a more modest 300 mph. Here, the geometry is reversed. The coils are on the vehicle and the ``projectiles`` are fixed along the roadbed. SERAPHIM operates not by embedding flux in a conductor, but by excluding it. In this propulsion ...
One of the most interesting discoveries of the X-ray Telescope and EUV Imaging Spectrometer (EIS) on board the Hinode solar observatory is the presence of persistent high temperature high speed outflows from the edges of active regions. Measurements by EIS indicate that the outflows reach velocities of 50 km/s with spectral line asymmetries approaching 200 km/s. It has been suggested that these outflows may lie on open field lines that connect to the heliosphere, and that they could potentially be a significant source of the slow speed solar wind. A direct link has been difficult to establish, however. In this letter, we use EIS measurements of spectral line intensities that are sensitive to changes in the relative abundance of Si and S as a result of the first ionization potential (FIP) effect, to measure the chemical composition in the outflow regions of AR 10978 over a period of 5 days in December ...
The spectral dependences of absorption photoinduced in a pure bismuth titanium oxide crystal by 532-nm laser pulses are studied. It is shown that optical absorption in the crystal in the range from 492 to 840 nm increases with increasing exposure. The photoinduced absorption relaxes in the dark for more than 60 hours. A model of photoinduced absorption is proposed which assumes the population of two trap centres with the normal energy distribution law for the concentrations of electrons photoexcited from donors to the conduction band. This model well describes the spectral dependences of photoinduced absorption by using the average ionisation energies of the traps E{sub 1} = 1.60 eV and E{sub 2} = 2.57 eV. The model is used to estimate the increase in the photorefractive sensitivity of a bismuth titanium oxide crystal in the near IR region, which was earlier observed after exposing the crystal to visible radiation. It is predicted that the ...
Nonevaporable getters (NEGs) have been extensively studied in the last several years for their sorption properties toward many gases. In particular, an innovative alloy as a thin film by magnetron sputtering was developed and characterized at the European Organization for Nuclear Research. It is composed of Ti-Zr-V and protected by an overlayer of palladium (Pd), according to a technology for which the authors got the licence. NEG-Pd thin films used in combination with ion getter pumps is a simple, easy way to handle pumping devices for ultrahigh and extremely high vacuum applications. To show how to apply this coating technology to the internal surface of different types of ion pumps, the authors carried out several tests on pumps of various shapes, sizes (in terms of nominal pumping speed), and types (diode, noble diode, and triode). Special care was taken during the thermal cycle of baking and activation of the pumps to preserve the internal ...
A ZephIR prototype wind lidar manufactured by QinetiQ was mounted on the nacelle of a Vestas V27 wind turbine and measurements of the incoming wind flow towards the rotor of the wind turbine were acquired for approximately 3 months (April - June 2009). The objective of this experiment was the investigation of the turbulence attenuation induced in the lidar measurements. In this report are presented results from data analysis over a 21-hour period (2009-05-05 12:00 - 2009-05-06 09:00). During this period the wind turbine was not operating and the line-of-sight of the lidar was aligned with the wind direction. The analysis included a correlation study between the ZephIR lidar and a METEK sonic anemometer. The correlation analysis was performed using both 10 minutes and 10 Hz wind speed values. The spectral transfer function which describes the turbulence attenuation, which is induced in the lidar measurements, was estimated by means of ...
The theoretical analysis of a partially-ionized hydrogen gas flow (gas temperatures of approximately 10,000 to 20,000 K) through a particular class of magnetohydrodynamic (MHD) generators and the preliminary design of these MHD generators as open cycle, electric power supplies are performed. Analysis of the gas flow through these ultra-high temperature MHD generators requires a coupled gas dynamics/radiative heat transfer solution. Gas dynamics are modeled by a set of quasi-one-dimensional, nonlinear differential equations which account for friction, convective and radiative heat transfer and the interaction between the ionized gas and applied magnetic field. Radiative heat transfer is modeled using non-gray, absorbing-emitting two- and three-dimensional P-1 approximations which permit an arbitrary variation of the spectral absorption coefficient with frequency. Gas dynamics and radiative heat transfer are coupled through the energy equation, ...
A back-propagation neural network technique is used at JET to extract plasma parameters like ion temperature, rotation velocities or spectral line intensities from charge exchange (CX) spectra. It is shown that in the case of the C VI CX spectra, neural networks can give a good estimation (better than +-20% accuracy) for the main plasma parameters (Ti, V{sub rot}). Since the neural network approach involves no iterations or initial guesses the speed with which a spectrum is processed is so high (0.2 ms/spectrum) that real time analysis will be achieved in the near future. 4 refs., 8 figs.
The spatio-temporal dynamics of an impinging shock/boundary layer interaction at Mach 2 and under incipient separation conditions, has been investigated experimentally by means of high-speed particle image velocimetry (PIV). The available PIV acquisition rate of up to 20 kHz permits a time-resolved characterization of the interaction. The dynamics of different flow regions?notably the separation region and the reflected shock?were quantified by means of temporal auto-correlation fields and pseudo-spectral analysis. The PIV data further enable to investigate the relationship between spatially extended flow features, such as shock position and bubble size, as well as the influence of the upstream boundary layer. The results confirm earlier studies that there is an important upstream effect o...
We study the phonon fluxes emitted when the condensate velocity crosses the speed of sound, i.e., in backgrounds which are analogue to that of a black hole. We focus on elongated one dimensional condensates, and on stationary flows. Our theoretical analysis and numerical results are based on the Bogoliubov-de-Gennes equation without any further approximation. The spectral properties of the fluxes and of the long distance density-density correlations are obtained, with and without an initial temperature. In realistic conditions, we show that the condensate temperature dominates the fluxes, and thus hides the presence of the spontaneous emission (the Hawking effect). We also explain why the temperature amplifies the long distance correlations which are intrinsic to this effect. This confirms that the correlations pattern offers a neat signature of the Hawking effect. Optimal conditions to observe the pattern are discussed.
We describe a liquid hydrogen droplet as an optical cavity via whispering gallery modes. We show that the droplet leads to an ultrahigh-cavity-Q value of 2.5x10{sup 9} in visible region. We show also that the high-Q droplet results in a huge Raman nonlinearity, generating a stimulated Raman comb series covering whole visible region.
Considerations for longevity of nuclear facilities and ease of decommissioning are of great importance for future nuclear power plants. To this end, a concept of an optimal structural concept for nuclear reactor buildings has been studied: the main feature of this concept is to utilize large-sized, light weight prefabricated members with ultrahigh strength materials. The following two items have been selected to study the prospective structure: (1) Applicability of ultrahigh strength materials for reinforced concrete shear walls (2) Construction using large sized prefabricated members As the first step (1), material and structural tests using ultrahigh strength materials, and the subsequent analysis of those tests for reinforced concrete shear walls, has been conducted. The positive results of this study show a bright future for the use of ultrahigh strength materials for the reinforced concrete shear ...
Gold and silver nanoparticles display extraordinarily large apparent refractive indices near their plasmon resonance (PR) wavelengths. These nanoparticles show good contrast in a narrow spectral band but are poorly resolved at other wavelengths in differential interference contrast (DIC) microscopy. The wavelength dependence of DIC contrast of gold/silver nanoparticles is interpreted in terms of Mie's theory and DIC working principles. We further exploit this wavelength dependence by modifying a DIC microscope to enable simultaneous imaging at two wavelengths. We demonstrate that gold/silver nanoparticles immobilized on the same glass slides through hybridization can be differentiated and imaged separately. High-contrast, video-rate images of living cells can be recorded both with and without illuminating the gold nanoparticle probes, providing definitive probe identification. Dual-wavelength DIC microscopy thus presents a new approach to the simultaneous ...
As with science, so with security--in both arenas, the extraordinary sensitivity of cryogenic sensors enables high-confidence detection and high-precision measurement even of the faintest signals. Science applications are more mature, but several national and international security applications have been identified where cryogenic detectors have high potential payoff. International safeguards and nuclear forensics are areas needing new technology and methods to boost speed, sensitivity, precision and accuracy. Successfully applied, improved nuclear materials analysis will help constrain nuclear materials diversion pathways and contribute to treaty verification. Cryogenic microcalorimeter detectors for X-ray, gamma-ray, neutron, and alpha-particle spectrometry are under development with these aims in mind. In each case the unsurpassed energy resolution of microcalorimeters reveals previously invisible spectral features of nuclear materials. ...
The rebuilt rotor of the 224 kW Magdalen Islands VAWT was installed in 1979 and has been operating at its design speed (36.6 rpm) for about one year. Agreement between measured and theoretical performance is generally good except that maximum power may exceed theoretical predictions. Measurements of drive train losses, torque and power ripple, and rotor stresses are discussed. Although peak-to-peak cyclic stress levels are low in relation to fatigue life limits, spectral analysis of stress data indicates that the 3-per-rev component is amplified by near-resonance with the first butterfly blade mode. This resonance was subsequently de-coupled by a damped connection between the blade struts and the central column. The major future project in the Canadian program is the design, construction and testing of a megwatt-scale VAWT in cooperation with Hydro Quebec. Preliminary desigh details of this turbine, known as Project Aeolus are briefly ...
Investigations of superdense compression touch on such problems as ultrahigh-frequency oscillations of matter in the generation of gravitational waves, the powerful pumping of hard coherent radiation, and the laboratory simulation of stellar interiors. This paper reviews the theory of supercompression and discusses some experiments involving multifoil collision supercompression.
The presence of highly heat-resistant spores of Bacillus sporothermodurans in ultrahigh-temperature or sterilized consumer milk has emerged as an important item in the dairy industry....Full Text Available
The mixed structure of a nuclear reactor building is composed of SC-columns, S-beams, S-joints and PCa-panels. Following the last report (Part 7)[1], the main test results of the mixed structure, that is, the deformation mode, strain distribution and shear strength, are described. The S-joints using ultrahigh strength materials had no buckling nor shear slipping. The proposed mixed structure resisted the external horizontal forces under integrated uniformity among SC-columns, S-joints and PCa-panels. It could be confirmed that the mixed structure can be established. (author)
The objective of this study is to comprehend the basic structural characteristics of box shaped mixed structures proposed for a future nuclear reactor building structure. Specimens of reinforced concrete precast panel walls of the mixed structures were prepared using ultrahigh strength materials. Two bending shear tests were conducted with a parameter of the quantity of reinforcement bars. The results include: (1) Relationship of shear stress and the angle of the structure, and (2) Failure mode. (author)
The methodology of achieving a high power density (HPD, or brake mean effective pressure) direct-injection Diesel engine has been studied, which is directed to using high fuel/air ratio, high-speed and ceramic engine components. Among the main thrust to achieve these engine changes for an advanced Diesel engine is the design of a high injection pressure (HIP) fuel system. During the course of the present study, two Cummins 903 engines mated with a Rutger-built HIP were employed to investigate the engine response to HIP and in-cylinder processes by using the Rutgers high-speed infrared (IR) spectral digital imaging system. Five separate technical publications were prepared to report results obtained from the study. The main findings include: The HIP system permits engine operation at an air/fuel ratio of as rich as 18 to 1 with smoke emission not worse than with the conventional mechanical (low pressure) injection system; A ...
operating at the maximal setting of speed control dials used to control their ...evaluates their energy performance when the speed control dial used ...FFUs when the speed control dial used for adjusting fan wheel speeds in each FFU was
verified via high-resolution spectral density measurements using the Hadamard Variance. .... spectral density measurements were made with the HF5390 ...
An application that provides a flexible and easy to use interface to the GAMMA spectral simulation package is described that is targeted at investigations using in vivo MR spectroscopic methods....Full Text Available
tions, final noise-power spectral density measurements were made. These measurements of the noise-power spectral density were not the desired phase- noise ...
FIG. 4. Power Spectral Density of the MAP W11 radiometer. The red and black traces are the power spectral density measurements of the two detectors on the ...
The ultra-high pressure waterjet technology was being evaluated at Florida International University (FIU) as a baseline technology. In conjunction with FIU's evaluation of efficiency and cost, this report covers the evaluation conducted for safety and health issues. It is a commercially available technology and has been used for various projects at locations throughout the country. The ultra-high pressure waterjet technology acts as a cutting tool for the removal of surface substrates. The Husky trademark pump feeds water to a lance that directs the high pressure water at the surface to be removed. The safety and health evaluation during the testing demonstration focused on two main areas of exposure. These were dust and noise. The dust exposure was found to be minimal, which would be expected due to the wet environment inherent in the technology, but noise exposure was at a significant level. Further testing for noise is recommended because of ...
Heat exchangers for high and ultrahigh temperatures are a need and a precondition to realise high efficient fossil fired power plants based on the so-called Externally Fired Combined Cycle (EFCC) or the Indirect Fired Gas Turbines (IFGT). The main target of both processes is to increase the thermal efficiency of existing power plants by approximately 25% resulting in the same decrease in fuel consumption and, therefore, in the same reduction of CO{sub 2} formation. The main activities of the MPA University of Stuttgart in this project is focused on the characterisation and qualification of the structural material of the ultrahigh temperature heat exchanger (UHTHE) necessary in the above mentioned processes. The influence of the temperature and load on the material behaviour have been analysed by means of tensile tests and creep tests. The effectiveness of different coating systems and the interaction between coating system and basic material ...
Ultra-high resolution radiographs can be obtained using synchrotron X-rays. A collaboration team consisting of K-JIST, POSTECH and YUMC has recently commissioned a new beamline (5C1) at Pohang Light Source (PLS) in Korea for medical applications using phase contrast radiology. Relatively simple image acquisition systems were set up on 5C1 beamline, and imaging studies were performed for resolution test patterns, mammographic phantom, and animals. Resolution test patterns and mammographic phantom images showed much better image resolution and quality with the 5C1 imaging system than the mammography system. Both fish and mouse images with 5C1 imaging system also showed much better image resolution with great details of organs and anatomy compared to those obtained with a conventional mammography system. A simple and inexpensive ultra-high resolution imaging system on 5C1 beamline was successfully implemented. The authors were able to acquire ...
Tailor die quenching in the hot stamping of quenchable steel sheets was developed to produce ultra-high strength steel formed parts having strength distribution. Local portions of the heated sheet were quenched by holding grooved tools at the bottom dead centre during the stamping. Non-contact portions were generated in the sheet by grooving the tools, and thus the strength in the contact portions is high owing to the quenching and that in the non-contact portions is low owing to the lack of the quenching. Hat-shaped products having a tensile strength of approximately 1.5GPa only at four corners were formed.
Mechanical properties of P-LDHA and V-ROL N steels of the Czech production are compared with other ultra-high strength steels produced in the world. The most important results can be summarized into following points: 1. Optimally heat treated P-LDHA steel exhibits substantially better strength characteristics then the V-ROL N steel. 2. Optimal tempering temperature of the P-LDHA steel is 300 C. 3. Basic mechanical properties of P-LDHA steel belong to the top of the UHS steels ranking and are well comparable with those of American 300 M steel. 4. In the low-cycle fatigue region, the P-LDHA steel exhibits slightly better fatigue resistance then the 300 M steel. On the other hand, the high-cycle fatigue resistance of 300 M steel is slightly better then that of the P-LDHA steel. (orig.)
Pd was deposited onto Si (111) 7x7 surface at approximately 700 K inside an ultrahigh vacuum transmission electron microscope. Plan-viewed transmission electron microscopy (TEM) observation indicated that the islands have two kinds of shapes, round and rectangular (one-dimensional) ones. In a diffraction pattern for the rectangular islands, extra spots along the <110> direction of the Si surface, spacing of which is 1/8 times as long as that of Si (220) spots, were seen. A high resolution TEM image showed the corresponding superstructure in the rectangular islands. In situ observation of the growing process of the rectangular islands showed repeat of introduction and relief of strains during the growth, suggesting that such superstructure would be constructed by stacking compositionally different phases or introducing defects so that the periodically maximized strain is relieved.
The effects of a modifier that contains Rare Earths (RE), low melting point alloy (Al-Bi-Sb) and Ca-Si alloy on an ultrahigh carbon steel containing 1.9wt.% C were studied. Microstructure characterization was carried out with optical microscopy (OM) and scanning electronic microscopy (SEM) combined with energy-dispersive spectrometry (EDS). Upon modification, the continuous eutectic carbide network structure was broken up and changed to a partly isolated and finer blocky structure in the as-cast alloy. Differential scanning calorimetry (DSC) revealed that the eutectoid temperature increased and the eutectic temperature decreased for the modified alloy. Modification also improved the impact toughness of the tempered steel, with a significant increase from 6.5 to 12.6Jcm^-^2, despite the har...
The individuality of production devices should be taken into account when statistical models are designed for parallelized devices. In the present work, a new clustering method, referred to as NC-spectral clustering, is proposed for discriminating the individuality of production devices. The key idea is to classify samples according to the differences of the correlation among measured variables, since the individuality of production devices is expressed by the correlation. In the proposed NC-spectral clustering, the nearest correlation (NC) method and spectral clustering are integrated. The NC method generates the weighted graph that expresses the correlation-based similarities between samples, and the constructed graph is partitioned by spectral clustering. A new statistical process monit...
An electron moving over the surface of a diffraction grating will transfer a part of its kinetic energy to radiation via a velocity synchronous coupling with a slow space harmonic component of the field. Since the phase velocity of a slow space harmonic is less than the speed of light, the slow components decay exponentially, or evanesce, with distance above the grating and the evanescence scale is determined by the product of the relative velocity, #beta#, the relative energy, #gamma#, and the wavelength #lambda#. Thus, in the relativistic regime, good electron - grating coupling can be maintained at beam heights that are greater than the emitted wavelength. In order to explore this regime a series of experiments have been carried out with moderately energetic beams and an experiment with the 70-MeV beam at the Accelerator Test Facility is in the planning stage. The work has two basic goals: the first is to explore the characteristics of the spontaneous emission ...
Outgoing longwave radiation (OLR) and low-level wind fields in the Atlantic and Pacific Intertropical Convergence Zone (ITCZ) are dominated by variability on synoptic time scales primarily associated with convectively coupled easterly waves during boreal summer and fall. This study uses spectral filtering of observed OLR data to capture the convective variability coupled to Pacific easterly waves. Filtered OLR is then used to isolate easterly waves in winds, temperature and humidity fields from TAO/TRITON and TAO/EPIC buoys, radiosondes, and gridded reanalysis products. Our analysis shows that while some of the Pacific easterly waves originate in the Atlantic, most of the waves appear to form and strengthen within the Pacific. Pacific easterly waves have wavelengths of 3300-5500 km and phase speeds of 9-13 m s-1. A warm, moist boundary layer is observed ahead of the convective wave, with moisture lofted quickly through the troposphere by deep ...
The use of high pressure waterjets (HPWJ) as oil barriers has been proposed and tested. It has been shown that a series of waterjets directed horizontally above the free water surface provide an effective means of containing or deflecting oil slicks. The waterjets generate a high speed air flow capable of moving the surface layer of the liquid. A numerical model is implemented to study the characteristics of the entrained turbulent air flow using the Spectral Element Method (SEM) and an algebraic turbulent model for the Reynolds stresses. A test of the code is done for turbulent Couette Flow to check the accuracy of the calculated shear stresses against published data. A parametric study is performed to evaluate the HPWJ system performance at various operating and design parameters which include manifold pressure, nozzle flow rate, nozzle characteristics, jet height and surface wave conditions. The total driving shear force and power required ...
In this paper structure and mechanical properties of PBZT and PBO fibers are briefly discussed. One limitation of the high-modulus polymeric fibers and ultrahigh-modulus carbon fibers in reinforced composites is their poor compressive strength. Issues related to the compressive strength of polymeric and carbon fibers are considered. 62 references, 7 figures, 4 tables.
High and ultra-high strength steels for pipelines are produced by properly handling the steel microstructure. The metallurgical principles involved in the microstructure control are presented, with emphasis on TMCP processing, that comprises conventional controlled rolling followed by accelerated cooling. (author)
The NREL Sensitized Solar Cell (SSC) Core Program supports the Solar America Initiative by: (1) targeting new devices and processes for commercialization by 2015 that are less expensive, more efficient, highly reliable, and environmentally benign; (2) collaborating with DOE OS/BES to conduct basic research targeting breakthroughs in key areas, such as ultra-high efficiency and/or ultra-low cost materials and devices.
This report contains detailed information of the research program entitled "Development of Bulk Nanocrystalline Cemented Tungsten Carbide Materials for Industrial Applications". The report include the processes that were developed for producing nanosized WC/Co composite powders, and an ultrahigh pressure rapid hot consolidation process for sintering of nanosized powders. The mechanical properties of consolidated materials using the nanosized powders are also reported.
An ASTER (advanced spaceborne thermal emission and reflection radiometer) is one of the image sensors. It is to be installed in an earth survey polar orbit platform satellite, EOS-AM1, which is to be launched in 1998, and it is going to start its operation. Data observed by the thermal infrared remote sensing of ASTER include the spectral emissivity, and the spectral emission reflectivity which is expressed by the function of temperature. It is required to overcome technical problems how to extract the spectral emissivity from the observed data. The spectral emissivity extracted from the remote sensing data by the MMD method, measured for samples collected in Cuprite area, Nevada, and/or measured at sampled points were compared to each other and discussed. The hemisphere spectral reflectivity, which is indirect spectral emissivity, agreed well with the direct ...
The so-called spectral dimension is a scale-dependent number associated with both geometries and field theories that has recently attracted much attention, driven largely though not exclusively by investigations of causal dynamical triangulations (CDT) and Horava gravity as possible candidates for quantum gravity. We advocate the use of the spectral dimension as a probe for the kinematics of these (and other) systems in the region where spacetime curvature is small, and the manifold is flat to a good approximation. In particular, we show how to assign a spectral dimension (as a function of so-called diffusion time) to any arbitrarily specified dispersion relation. We also analyze the fundamental properties of spectral dimension using extensions of the usual Seeley-DeWitt and Feynman expansions, and by saddle point techniques. The spectral dimension turns out to be a useful, robust ...
Realization of the scale of spectral responsivity of the detectors in the Directorate of Measures and Precious Metals (DMDM) is based on silicon detectors traceable to LNE-INM. In order to realize the unit of spectral irradiance in the laboratory for photometry and radiometry of the Bureau of Measures and Precious Metals, the new method based on the calibration of the spectroradiometer by comparison with standard detector has been established. The development of the method included realization of the System of Spectral Comparisons (SSC), together with the detector spectral responsivity calibrations by means of a primary spectrophotometric system. The linearity testing and stray light analysis were preformed to characterize the spectroradiometer. Measurement of aperture diameter and calibration of transimpedance amplifier were part of the overall experiment. In this paper, the developed method is ...
Realization of the scale of spectral responsivity of the detectors in the Directorate of Measures and Precious Metals (DMDM) is based on silicon detectors traceable to LNE-INM. In order to realize the unit of spectral irradiance in the laboratory for photometry and radiometry of the Bureau of Measures and Precious Metals, the new method based on the calibration of the spectroradiometer by comparison with standard detector has been established. The development of the method included realization of the System of Spectral Comparisons (SSC), together with the detector spectral responsivity calibrations by means of a primary spectrophotometric system. The linearity testing and stray light analysis were preformed to characterize the spectroradiometer. Measurement of aperture diameter and calibration of transimpedance amplifier were part of the overall experiment. In this paper, the developed method is ...
Another difference lies in the speed of star evolution. 2. Computation of Stellar Structure and Their Evolution. The structure of stars at certain instants ...
Two-year uninterrupted sodar measurements of vertical profiles of wind speed and direction in the height range 40 to 250-500 m were carried out in two points of Moscow megalopolis. Seasonal and diurnal courses of mean speed profiles, wind speed distributions, wind roses and occurrence of strong and weak wind speed events are shown. Influence of urban heat island and orography on wind field is discussed.
The idle speed of an internal combustion engine is controlled in response to a variable ignition timing control signal from a microcomputer. The microcomputer derives this control signal as a function of the magnitude of engine speed variation which occurs during engine idle periods to cause the ignition timing to vary quickly in response to a transitory engine load variation. An auxiliary air delivery system may be advantageously incorporated in the idle speed control system to cooperate with the ignition timing control in response to the engine speed variation.
Many animals use the spectral distribution of light to guide behaviour, but whether they have colour vision has been debated for over a century. Our strong subjective experience of colour and the fact...Full Text Available
The capability to image tissue motion such as blood flow through an endoscope could have many applications in medicine. Spectrally encoded endoscopy (SEE) is a recently introduced technique...Full Text Available
Purpose.To investigate the characteristics of a spectral-domain optical coherence tomography (SD-OCT) image phenomenon known as the mirror artifact, calculate its prevalence, analyze...Full Text Available
The 3-D spectral-domain optical coherence tomography (SD-OCT) images of the retina often do not reflect the true shape of the retina and are distorted differently along the x and y...Full Text Available
We present a dynamical spectral model for Large Eddy Simulation of the incompressible magnetohydrodynamic (MHD) equations based on the Eddy Damped Quasi Normal Markovian approximation. This model extends classical spectral Large Eddy Simulations for the Navier-Stokes equations to incorporate general (non Kolmogorovian) spectra as well as eddy noise. We derive the model for MHD and show that introducing a new eddy-damping time for the dynamics of spectral tensors in the absence of equipartition between the velocity and magnetic fields leads to better agreement with direct numerical simulations, an important point for dynamo computations.
... Although other authors had made cross-spectral density measurements, Corcos pointed to the importance of this function as indicative of the true ...
Ozsvath and Szabo show that there is a spectral sequence whose E^2 term is the reduced Khovanov homology of L, and which converges to the Heegaard Floer homology of the (orientation reversed) branched double cover of S^3 along L. We prove that the E^k term of this spectral sequence is an invariant of the link L when k>2. If L is a transverse link, then we show that Plamenevskaya's transverse invariant gives rise to a transverse invariant of L in each of these higher terms.
A multi-spectral Schottky barrier infrared detector array in which individual pixels of radiation from a remote radiating object are detected by two or more Schottky barrier infrared radiation detectors each having a different spectral response so as to provide a ''color'' discrimination for the array.
A multi-spectral Schottky barrier infrared detector array in which individual pixels of radiation from a remote radiating object are detected by two or more Schottky barrier infrared radiation detectors each having a different spectral response so as to provide a ''color'' discrimination for the array.
Subsurface and surface coalfires are a serious problem in many coal-producing countries. Combustion can occur within the coal seams (underground or surface), in piles of stored coal, or in spoil dumps at the surface. While consuming a non renewable energy source, coalfires promote several environmental problems. Among all GHGs that are emitted from coalfires, CO2 is the most significant because of its high quantity. In connection to this environmental problem, the core aim of the present research is to develop a hyperspectral remote sensing and radiative transfer based model that is able to estimate CO2 concentration (ppmv) from coalfires. Since 1960s remote sensing is being used as a tool to detect and monitoring coalfires. With time, remote sensing has proven a reliable tool to identify and monitor coalfires. In the present study multi-temporal, multi-sensor and multi-spectral thermal remote sensing data are being used to detect and monitor coalfires. Unlike the ...
Subsurface and surface coalfires are a serious problem in many coal-producing countries. Combustion can occur within the coal seams (underground or surface), in piles of stored coal, or in spoil dumps at the surface. While consuming a non renewable energy source, coalfires promote several environmental problems. Among all GHGs that are emitted from coalfires, CO2 is the most significant because of its high quantity. In connection to this environmental problem, the core aim of the present research is to develop a hyperspectral remote sensing and radiative transfer based model that is able to estimate CO2 concentration (ppmv) from coalfires. Since 1960s remote sensing is being used as a tool to detect and monitoring coalfires. With time, remote sensing has proven a reliable tool to identify and monitor coalfires. In the present study multi-temporal, multi-sensor and multi-spectral thermal remote sensing data are being used to detect and monitor coalfires. Unlike the ...
Current methods to calculate dose distributions with organ motion can be broadly classified as 'dose convolution' and 'fluence convolution' methods. In the former, a static dose distribution is convolved with the probability distribution function (PDF) that characterizes the motion. However, artifacts are produced near the surface and around inhomogeneities because the method assumes shift invariance. Fluence convolution avoids these artifacts by convolving the PDF with the incident fluence instead of the patient dose. In this paper we present an alternative method that improves the accuracy, generality as well as the speed of dose calculation with organ motion. The algorithm starts by sampling an isocenter point from a parametrically defined space curve corresponding to the patient-specific motion trajectory. Then a photon is sampled in the linac head and propagated through the three-dimensional (3-D) collimator structure corresponding to a particular MLC segment ...
A process is described for maintaining the proportions of each coal in a coal blend at a desired level. The process involves (1) making a spectral analysis, preferably by infrared spectrometry, of at least one sample of the coal blend, the sample having known desired proportions of each coal, (2) making a spectral analysis of the coal blend sample of unknown proportions of each coal, (3) comparing the spectral analyses of steps (1) and (2), and (4) upon noting a significant difference between the spectral analyses of steps (1) and (2), making adjustments to achieve a final coal blend having proportions of each coal closer to those of the blend of known desired proportions of each coal. The relationship of the aromatic to aliphatic groupings is preferably determined by spectral analysis of each coal sample. This process is particularly useful on-line in the production of blast ...
High-power arc lamp design has enabled ultrahigh-temperature (UHT) annealing as an alternative to conventional rapid thermal processing (RTP) for ultrashallow junction formation. The time duration of the UHT annealing technique is significantly reduced from those obtained through conventional RTP. This difference in time may offer the ability to maintain a highly activated ultrashallow junction without being subjected to transient enhanced diffusion (TED), which is typically observed during postimplant thermal processing. In this study, two 200-mm (100) n-type Czochralski-grown Si wafers were preamorphized with either a 48- or a 5-keV Ge"+ implant to 5x10"1"4 cm"2, and subsequently implanted with 3-keV BF_2"+ molecular ions to 6x10"1"4 cm"2. The wafers were sectioned and annealed under various conditions in order to investigate the effects of the UHT annealing technique on the resulting junction characteristics. The main point of the paper is to show that the UHT ...
A film of GaSb grown epitaxially on a Si substrate is a direct transition semiconductor useful for application as a light source in Si photonics and channel material in next-generation field effect transistors because its energy bandgap is close to the optical fibre communication wavelength and it possesses high carrier mobility. Here, we report a novel method for heteroepitaxial growth of high-quality GaSb/Si films, despite having a lattice mismatch as large as ? 12%, using elastically strain-relaxed GaSb nanodots with ultrahigh density as seed crystals for film growth. The nanodot seed crystals were grown epitaxially by restricted contact with the Si substrate through nanowindows in an ultrathin SiO(2) film on the Si substrate. A light-emitting diode containing GaSb/Si films with a thickness of ? 90 nm fabricated by this method operated at room temperature. The growth method was also used to fabricate AlGaSb films of high quality. Our method provides a new avenue ...
Pd was deposited onto Si (111) 7x7 surface at approximately 700 K inside an ultrahigh vacuum transmission electron microscope. Plan-viewed transmission electron microscopy (TEM) observation indicated that the islands have two kinds of shapes, round and rectangular (one-dimensional) ones. In a diffraction pattern for the rectangular islands, extra spots along the <110> direction of the Si surface, spacing of which is 1/8 times as long as that of Si (220) spots, were seen. A high resolution TEM image showed the corresponding superstructure in the rectangular islands. In situ observation of the growing process of the rectangular islands showed repeat of introduction and relief of strains during the growth, suggesting that such superstructure would be constructed by stacking compositionally different phases or introducing defects so that the periodically maximized strain is relieved.
The crack growth behavior and fracture toughness of two laminated metal composites (6090/SiC/25p laminated with 5182 and ultrahigh-carbon steel laminated with brass) have been studied in both ``crack arrester`` and ``crack divider`` orientations. The mechanisms of crack growth were analyzed and extrinsic toughening mechanisms were found to contribute significantly to the toughness. The influence of laminate architecture (layer thickness and component volume function), component material properties and residual stress on these mechanisms and the resulting crack growth resistance are discussed.
During the past two decades, the explosives synthetic effort at Los Alamos has been directed toward energetic heterocylic compounds and has produced some useful thermally stable explosives. The recent evolution of crystal-density predictive methods is guiding our current efforts toward ultrahigh performance explosives. Much of our effort is now on the development of new methods for preparing unique nitro compounds that are inaccessible by conventional techniques. This paper reviews the Los Alamos synthetic program with emphasis on the development of novel thermally stable explosives, and current efforts to synthesize high-density/performance explosives will be discussed.
OBJECTIVESAlthough several studies suggest that slow gait speed is a predictor of falls, it may also be a protective mechanism to prevent falls. Further, fast walking...Full Text Available
It has been predicted that geometrically similar animals would swim at the same speed with stroke frequency scaling with mass−1/3. In the present study, morphological and behavioural...Full Text Available
Optical coherence microscopy (OCM) is a promising technique or high resolution cellular imaging in human tissues. An OCM system for high-speed en face cellular resolution imaging...Full Text Available
High speed experimental tests provided data on six parametric cylindrical roller bearings. Four bearing variables were evaluated and the results were correlated with the analytical model developed under Naval Air Propulsion Center Contract N00140-76-C-038...
This patent describes a display unit of a speedometer for an automobile, comprising: a constant speed running circuit capable of producing output signals indicative of a desired car speed; an actual car speed operational circuit capable of producing output signals indicative of actual car speed; a comparing circuit for comparing the amplitudes of the output signals of the constant speed running operational circuit and the actual car speed operational circuit; bar graph decoders receiving the output signals from the constant speed running operational circuit and the actual car speed operational circuit; an EX-OR circuit having inputs coupled to respective bar graph decoders and having an output; and OR circuit having inputs coupled to respective bar graph decoders and having an output; selector means coupled to the output ...
A high-speed fiber-based network for the transmission and display of digitized full-motion cardiac images has been developed. Based on Asynchronous Transfer Mode (ATM), the network is scaleable, meaning...Full Text Available
Given a Schwarzschild black-hole, the frame sigma at rest with respect to the Schwarzschild metric are chosen as reference-frames. In this locally non-inertial frames, a free falling body is shown to reach the speed of light on the horizon and then to travel faster-than-light inside the horizon. The usual Szekeres-Kruskal (SK) coordinates represent themselves frames that (with respect to the frames sigma) travel at subliminal speed outside, at luminal speed on, and at superluminal speed inside the horizon (so that SK frames always describe any free falling body as a standard, slower-than-light object). At last, black-holes are shown to be possible sources of tachyons.
Success in improving hydropower project efficiency has opened more global markets for variable-speed generator technology. Manufacturers continue to test the markets as the technology evolves. The potential of variable-speed application becomes evident considering that more than 150 pumped storage plants, with a combined capacity exceeding 100,000 MW, are in operation globally.
The UIC High Speed Department's flagship event is the World Congress on High Speed Rail held approximately every three years. This year's congress will take place in Amsterdam from 17 to 19 March 2008. (orig.)
In general, the tickover speed of a car engine is made sufficiently high, in order to permit an assumed maximum load to be taken from the engine at tickover. This setting of the tickover speed is usually done by stops in the fuel supply. Matching the actual load would lead to lower fuel consumption, without any danger of the engine stalling. The purpose of the invention is to provide a tickover speed controller, so that the tickover speed is adjusted by electronic control equipment, independently of the machine load. The fuel consumption on tickover is reduced and the emission of noxious substances is decreased. The electro-magnetic control of the throttle valve tickover setting is explained by extensive section drawings of the system. This process dispenses with the special tickover cams for a cold start.
Wind speed has been measured in Patenga, Cox`s Bazar, Kuakata, Moheshkhali, and Noakhali by the computerized anemometers. The wind computers have been installed at 20 meters height. According to this study annual average wind speeds in the coastal regions of Bangladesh are greater than 6.5 m/s at the height of 20 meters. It has been observed that during day times (8 a.m. to 7 p.m.) wind speeds are about 30 to 40% higher than the average values. The value of the power exponent {alpha} has been determined in the above sites and it is 0.139. So, at 40 meters height the annual average wind speed is about 7.15 m/s. So, wind speeds in the coastal regions of Bangladesh are suitable for both water pumping and electricity generation. Details are given in this paper with graphical and analytical representations. (author)
Swirling speed in a direct injection diesel engine was measured by a laser doppler velocimeter. Intake port geometry and engine speed were changed as factors affecting the swirling flow to study the distribution of swirling flow speed. The distribution of swirling flow speed changes complicatedly owing to axial nonsymmetry during intake process but becomes simple shape of axial symmetry during compression process after closing intake valve. But if this is assumed as the rigid swirl shape, the difference due to each intake port cannot be expressed but also large error may be possible to appear close to the cylinder wall. The distribution of swirling flow speed during compression process changes similarly, nearly proportinal to engine speed. But the similarity is higher at the middle period in compression process than at the end period in compression period. Axial ...
Because of its high price, the extra virgin olive oil is frequently target for adulteration with lower quality oils. This paper presents an innovative optical technique capable of quantifying the adulteration of extra virgin olive oil caused by lowergrade olive oils. It relies on spectral fingerprinting the test liquid by means of diffuse-light absorption spectroscopy carried out by optical fiber technology in the wide 400-1700 nm spectral range. Then, a smart multivariate processing of spectroscopic data is applied for immediate prediction of adulterant concentration.
A subsurface imaging system is utilized to test the ability of the spectral polarization difference imaging technique for deep subsurface imaging in tissues. The illumination of the system is derived from compact class III lasers in the red and NIR spectral region and, alternatively, from a white light source and selection of the appropriate illumination wavelength using band-pass optical filters. The experimental results demonstrate detection and imaging of a high-scattering object located up to 1.5 cm underneath the surface of a host chicken tissue.
Secondary deuterium in the atmosphere are produced in interactions by primary cosmic rays. The shape of their energy spectrum depends on the primary cosmic ray spectrum incident at the top of the atmosphere. At high energies, the spectral shape depends on the primary spectrum of helium and heavy nuclei. However, at very low energies, specially below the geomagnetic cut-off, the spectral shape depends on the evaporation and recoil processes and hence almost independent of the spectral shape of the primary radiation. It is undertaken a calculation of the secondary deuterium spectrum at small atmospheric depths at various latitudes and the results will be presented.
The authors have measured the noise of MOS transistors of the United Technology Microelectronics Center (UTMC) 1.2 [mu]m radiation hardened CMOS P-well process from the weak to moderate inversion region. The noise power spectral densities of both NMOS and PMOS devices were measured from 1 KHz to 50 MHz. The bandwidth was chosen such that the important components of the spectral densities such as the white thermal noise and the 1/f noise could be easily resolved and analyzed in detail. In this paper the effects of different device terminal DC biases and channel geometries on the noise are described.
A temperature gradient across a thick ({ge}.1mm) film selective emitter will produce a significant reduction in the spectral emittance from the no temperature gradient case. Thick film selective emitters of rare earth doped host materials such as yttrium-aluminum-garnet (YAG) are examples where temperature gradient effects are important. In this paper a model is developed for the spectral emittance assuming a linear temperature gradient across the film. Results of the model indicate that temperature gradients will result in reductions the order of 20{percent} or more in the spectral emittance. {copyright} {ital 1997 American Institute of Physics.}
... necessary to allow for the effata nr the finits size of the oressure tranaducer on both the root mean square and power spectral density measurements ...
... 14. Pfeifer, HJ, (1986), "Correlation and Spectral Density Measurements by LDA," Proceedings of the 5th International Congress on Applications of ...
... Although cytologic evaluation of urine specimens is a standard Cesar Angeletti, MD ... 3. Rodriguez-Alonso A, Pita-Fernandez S, Gonzalez-Carrero J, ...
indicated for the phase spectral density measurements; how- ever, Ref. 7 provides a very tentative estimate of : ORW ~ 2 ><10"'(RW); Ta = 1000 seconds ...
structures made out of composite laminates and/or composite sandwich panels. A Spectral Finite Element Method (SFEM) [19, 20] is used for evaluating the ...
A tunable diode laser is used to obtain infrared spectra of carbon dioxide in biological materials. The spectral resolution is sufficient to readily distinguish differing isotopic species. The technique may prove useful in clinical tests.
A diffuse-reflectance capability for the Fourier transform infrared spectrometer at the Y-12 Plant Laboratory has been implemented. A sample cell with a 25 to 400/sup 0/C temperature-controlled sample stage and an ultrahigh-vacuum-to-atmospheric pressure gas-handling capability has been developed. Absorbance of light from the spectrometer beam, resulting from the beam being scattered from a powder sample, can be measured. This capability of detecting molecular species on and in powders is to be used to study chemisorption on actinide and rare-earth metals, alloys, and compounds. Cell design is described along with experiments demonstrating its performance in detecting moisture absorption on uranium oxide, moisture and carbon dioxide absorption on the lithium hydride/hydroxide system, and carbon dioxide absorption on potassium borohydride. 13 figures.
A procedure was developed for separating rubidium from irradiated aluminum encapsulated uranium. The separations procedure produces a final ultra-high purity RbCl product for subsequent high performance mass spectrometric analysis. The procedure involves first removing most of the macro-components and fission products by strong base anion exchange using, first, concentrated HCl, then oxalic acid media and second, selectively separating rubidium from alkaline-earth ions and other alkali-metal ions, including cesium, using Bio-Rex-40 cation-exchange resin. The resultant RbCl is then put through a final vacuum sublimation step. Ultra-pure reagents and specially clean glassware are used throughout the procedure to minimize contamination by naturally-occurring rubidium.
A procedure was developed for separating rubidium from irradiated aluminum encapsulated uranium. The separations procedure produces a final ultra-high purity RbCl product for subsequent high performance mass spectrometric analysis. The procedure involves first removing most of the macro-components and fission products by strong base anion exchange using, first, concentrated HCl, then oxalic acid media and second, selectively separating rubidium from alkaline-earth ions and other alkali-metal ions, including cesium, using Bio-Rex-40 cation-exchange resin. The resultant RbCl is then put through a final vacuum sublimation step. Ultra-pure reagents and specially clean glassware are used throughout the procedure to minimize contamination by naturally-occurring rubidium.
The goal of this research program is to determine whether pulsed laser deposition is an effective alternative method for growing TiCN thin films. Pulsed laser deposition (PLD) is chosen because of its well-documented capability for growing uniform, stoichiometric films in ultra-high vacuum or gaseous environments. Processing of thin films by PLD is also achieved at relatively low temperatures compared with CVD processing. Given these attributes, the primary objectives in this article are to determine whether nitrogen may be readily incorporated into films resulting from the laser-ablation of TiC in an N{sub 2} environment, determine what effect nitrogen has on mechanical properties, and determine whether nitrogen incorporation is strongly influenced by processes unrelated to laser deposition (e.g., thermally-activated surface reactions).
The growth of thin Pd[sub 2]Si films on Si(111) surfaces is studied using [ital in] [ital situ] transmission electron microscope under ultrahigh vacuum conditions. No immediate reaction of deposited Pd with Si is observed at room temperature. At [similar to]200 [degree]C, uniform Pd[sub 2]Si films can be formed. The thin Pd[sub 2]Si films are found to grow into strained islands at elevated temperatures. Interfacial misfit dislocations associated with interfacial steps propagate across the strained islands, causing the islands to grow layer-by-layer at the interface. The strain fields associated with the misfit dislocations are believed to be responsible for this behavior.
During the early 1970s, controversy developed over the possible biological effects of electric fields from new 500-kilovolt and 765-kilovolt transmission lines. This, along with growing interest in advancing transmission voltage into the ultrahigh-voltage range (1000 kilovolts and above), led to the initiation of numerous research projects. Several reviews of this research by scientists in the US and other countries indicate that transmission lines have not been proven to be a health hazard to people or animals. The issue remains controversial, however, because research has confirmed some subtle effects of electric fields, and because it is an inseparable part of the public opposition that often accompanies the siting of high-voltage transmission lines. In addition, there is renewed interest in magnetic fields, including a possible association between such fields and human cancers. 2 figures, 2 tables.
We present and characterize a very efficient optical device that employs the plasma mirror technique to increase the contrast of high-power laser systems. Contrast improvements higher than 104 with 50% transmission are shown to be routinely achieved on a typical 10 TW laser system when the pulse is reflected on two consecutive plasma mirrors. Used at the end of the laser system, this double plasma mirror preserves the spatial profile of the initial beam, is unaffected by shot-to-shot fluctuations, and is suitable for most high peak power laser systems. We use the generation of high-order harmonics as an effective test for the contrast improvement produced by the double plasma mirrors. (authors)
A high-average power (kW) infrared (IR) free-electron laser (FEL) is currently being commissioned for the Jefferson Laboratory FEL User Facility. The IR FEL is driven by a unique superconducting rf linac which is recirculated to recover electron beam power that is not radiated in the FEL. The design and installation of the vacuum system for the FEL involved particular attention to minimizing particulate contamination which could cause problems with the superconducting acceleration cavities and the high power FEL optics. Particulate contamination levels of all vacuum components were monitored during the cleaning process using laser scattering. Cleaning, transport, and installation procedures were developed to minimize the contamination of the complete system. We will summarize a data base we compiled of particulate contamination levels of the various components installed in the FEL vacuum system.
It is shown that it is necessary to take into account locality of the analysis and to introduce additional corrections for partial capture of matrix and fluorescent subexcitation by matrix during quantitative X-ray spectral microanalysis of finely dispersed materials. Cast two-phase (#alpha#+#beta#) titanium alloy VT3-1 is chosen as an investigation object.
CdTe/SnTe heterojunctions, prepared by EDRI (evaporation-diffusion en regime isotherme) and CSVT (close spaced vapour transport) techniques, have a spectral response in a wide wavelength range (0.3 - 1.5 ..mu..m) which exhibits two distinct bands, corresponding to carrier generation in each material of the couple. Experimental results are interpreted in terms of a Schottky diode model. (orig.).
The application of a Compact Airborne Spectrographic Imager to assessment and monitoring of lakes in a lignite open cast mining area in central Germany is described. The imager was used in combination with additional ground experiments, such as field spectroscopy and water sampling. The spectral characteristics of an instrument under development for monitoring geochemical and hydrological processes are presented. Summary form only.
A general account of the properties, growing technology and annealing of lead-tin-telluride single crystals is given. Photoconductors were made for the 8 to 14 micron. spectral range and responsivity, detectivity and spectral response measurements showed satisfactory results. Improvement in the growing and annealing of the single crystals promise good performance in the near future.
Recent experimental and theoretical studies of two-dimensional (2D) turbulence reveal that spectrally condensed turbulence which is a system of coupled large-scale coherent flow and broadband turbulence, is similar to plasma turbulence near the L-H transition threshold. Large condensate vortices fed via the turbulent inverse energy cascade, can control both the level of the broadband turbulence by shear decorrelation, and the energy injected into turbulence at the forcing scale via sweeping of the forcing-scale vortices. The interaction between these ingredients of spectrally condensed fluid turbulence is in many aspects similar to the interactions in the zonal flow-GAMs-turbulence system in plasma. In this paper we overview recent results on condensed 2D turbulence and present evidence of interaction between its three components: condensate structures, turbulence and forcing-scale vortices. This is compared with the modifications in the ...
We report on the spectral cross-calibration results of the Konus-Wind, the Suzaku/WAM, and the Swift/BAT instruments using simultaneously observed gamma-ray bursts (GRBs). This is the first attempt to use simultaneously observed GRBs as a spectral calibration source to understand systematic problems among the instruments. Based on these joint spectral fits, we find that 1) although a constant factor (a normalization factor) agrees within 20% among the instruments, the BAT constant factor shows a systematically smaller value by 10-20% compared to that of Konus-Wind, 2) there is a systematic trend that the low-energy photon index becomes steeper by 0.1-0.2 and Epeak becomes systematically higher by 10-20% when including the BAT data in the joint fits, and 3) the high-energy photon index agrees within 0.2 among the instruments. Our results show that cross-calibration based on joint spectral analysis is an ...
We study the spectral evolution of pulsar wind nebulae (PWNe) taking into account the energy injected when they are young. We model the evolution of the magnetic field inside a uniformly expanding PWN. Considering time-dependent injection from the pulsar and coolings by radiative and adiabatic losses, we solve the evolution of the particle distribution function. The model is calibrated by fitting the calculated spectrum to the observations of the Crab Nebula at an age of a thousand years. The spectral evolution of the Crab Nebula in our model shows that the flux ratio of TeV #gamma#-rays to X-rays increases with time, which implies that old PWNe are faint in X-rays, but not in TeV #gamma#-rays. The increase of this ratio is because the magnetic field decreases with time and is not because the X-ray emitting particles are cooled more rapidly than the TeV #gamma#-ray emitting particles. Our spectral evolution model matches ...
Based on a detailed analysis of the inter-relationship in the current, voltage, electromagnetic torque and ratio of the difference between the speed of rotor and the speed of rotary magnetic field to the later in the motor, the root cause was point out, which leads to the protection fuses' failure of the motor in the starting stage, which drives the turbine-generator set to rotate at low speed before its startup. Two solutions to avoid the situation are proposed, too. (authors)
Recent research work on adjustable speed pumped storage plants conducted in Japan, the USA and Europe suggests that they have many advantages over fixed-speed plants, and can contribute to power system regulation even in pump mode. This paper describes two types of static frequency converter for such pumped storage plants, especially those with greatly fluctuating heads. The design characteristics and operation of the doubly fed induction machine and the synchronous machine with DC link converter are set out and the devices compared. (UK)
High-pressure, lean, premixed methane/air flames are investigated experimentally to determine turbulent flame speeds (s{sub T}). The results are based on the statistical analysis of single-shot OH-PLIF images. The influences of pressure (p = 5 - 14.4 bars) and equivalence ratio ( {phi} 0.43 - 0.56) on the turbulent flame speed are discussed. The analysis reveals that s{sub T} is independent of pressure and it depends strongly on equivalence ratio. The turbulent flame speed at {phi} = 0.56 is about 3 times higher than at {phi} = 0.43 because of the higher integral reaction rate caused by the higher fuel concentration and therefore higher adiabatic flame temperature. (author)
... water content according to the hydrometeor type. ... the documentation and the movement personnel and ... Dyer, RM, 1970: Particle fall speeds within ...
We revisit a recently proposed agent-based model of active biological motion and compare its predictions with own experimental findings for the speed distribution of bacterial cells, Salmonella typhimurium. Agents move according to a stochastic dynamics and use energy stored in an internal depot for metabolism and active motion. We discuss different assumptions of how the conversion from internal to kinetic energy d(v) may depend on the actual speed, to conclude that d 2 v ? with either ? = 2 or 1 ? < 2 are promising hypotheses. To test these, we compare the model?s prediction with the speed distribution of bacteria which were obtained in media of different nutrient concentration and at different times. We find that both hypotheses are in line with the experimental observations, with ? bet...
lytical Comparison of Turbine-Blade Cooling System Designed for a. TurboJet Engine Operat- at Supersonic Speed and Altitude. I1 -. Air-C~Oling Systems. ...
roller bearing with a one-piece inner ring. The lubricant experimental data on high-speed roller .... roller bearing. The outer ring of the test bearing was ...
We present a new modular traffic signs recognition system, successfully applied to both American and European speed limit signs. Our sign detection step is based only on shape-detection (rectangles or circles). This enables it to work on grayscale images, contrary to most European competitors, which eases robustness to illumination conditions (notably night operation). Speed sign candidates are classified (or rejected) by segmenting potential digits inside them (which is rather original and has several advantages), and then applying a neural digit recognition. The global detection rate is ~90% for both (standard) U.S. and E.U. speed signs, with a misclassification rate 150 minutes of video. The system processes in real-time ~20 frames/s on a standard high-end laptop.
Conventional interconnect and switching technology is rapidly becoming a critical issue in the realization of systems using high speed silicon and GaAs based technologies. In recent years clock speeds and on-chip density for VLSI/VHSIC technology has made packaging these high speed chips extremely difficult. A strong case can be made for using optical interconnects for on-chip/on-wafer, chip-to-chip and board-to-board high speed communications. GaAs integrated optoelectronic circuits (IOC's) are being developed in a number of laboratories for performing Input/Output functions at all levels. In this paper integrated optoelectronic materials, electronics and optoelectronic devices are presented. IOC's are examined from the standpoint of what it takes to fabricate the devices and what performance can be expected.
Rotatostereoradiographic (RSRG) images are displayed in an oscillating, rotational manner. While reviewing these rotating images, the radiologist may become psychologically irritated by the rotation. A rapidly rotating display of linear subjects gives one three-dimensional depth information. This three-dimensional sense is lost if the rotation speed is too slow. The authors of this paper determined the slowest possible rotating display speed that allows perception of three-dimensional depth information minimizing psychological irritation. In the RSRG device (Shimadzu ROTATO-360), an x-ray tube coupled with an image intensifier rotates through a 180 degrees arc in 1.8 or 2.25 seconds. Both rotation times could be doubled. The images were displayed at four different speeds, covering the 180 degrees arc in 1.8, 2.25, 3.6, and 4.5 seconds.
During a high speed road traffic accident, a 26-year-old man suffered multiple fractures of his thoracic vertebrae and bilateral pneumothoraces. The day after admission and commencement of nasogastric...Full Text Available
7.5.6 Conclusions of the Generic Metroplex Queueing Simulation . ...... the systemwide arrival delays incurred at the metroplex terminal-area ...... assignment rules, estimated nominal transit speeds or times by domain, and stochastic ...
A sodium-water reaction drove from the single tube break in steam generator of FBR might overheat labor tubes rapidly under internal pressure loadings. If the temperature of tube wall becomes too high, it has to be evaluated that the stress of tube does not exceed the material strength limit to prevent the propagation of tube rupture. This study clarified the tensile and creep properties of Mod.9Cr-1Mo steel at ultra-high temperature which will be used in evaluation of the tube burst by sodium-water reaction. The strain rates for tensile test are from 10%/min to 10%/sec, and creep-rupture time is maximum 277sec. The range of test temperature is 700degC to 1300degC. The main results obtained were as follows; (1) The evaluation data on the relationship between tensile strength and strain rate and creep-rupture strength in shorter time on Mod.9Cr-1Mo steel were acquired. (2) Short-term mechanical properties of Mod.9Cr-1Mo steel were evaluated based on the results of ...
The WEGA stellarator is used to confine low temperature, overdense (densities exceeding the cut-off density of the heating wave) plasmas by magnetic fields in the range of B=50-500 mT. Microwave heating systems are used to ignite gas discharges using hydrogen, helium, neon or argon as working gases. The produced plasmas have been analyzed using Langmuir and emissive probes, a single-channel interferometer and ultra-high resolution Doppler spectroscopy. For a typical argon discharge in the low field operation, B=56 mT, the maximum electron density is n{sub e}{proportional_to}10{sup 18} m{sup -3} with temperatures in the range of T=4-12 eV. The plasma parameters are determined by using Langmuir probes and are cross-checked with interferometry. It is demonstrated within this work that the joint use of emissive probes and ultra-high resolution Doppler spectroscopy allows a precise measurement of the radial electric field. The focus of this work is ...
On-orbit spectral calibration of hyperspectral imaging data is a key step for quantitatively analyzing them. Like the atmospheric correction, accurate spectral calibration is very necessary for improved studies of land or ocean surface properties. Based on the previous literatures, a new method which coupled an optimization algorithm was developed to simultaneously retrieve the central wavelength and the full width at half maximum (FWHM) of the hyperspectral sensor without needing the in situ reflectance spectra. Firstly, the Hyperion data set simulated using MODTRAN4 with the Hyperion spectral specification was used to test the new method, and the results indicated that the maximum error was less than 0.1 and 0.7 nm for central wavelength and FWHM respectively when the spectral shift is 5 nm. Then the algorithm was applied to the Hyperion data acquired on May 20, 2008 over Heihe River Basin and it was ...
As the ground state potential curve is strongly related to spectral line shapes, the minumum position of the ground state potential is obtained from the experiemental absorption profile k({delta}{nu}, T) at high density of the radiating atoms. The temperature dependence of the absorption processes of Hg and Cd lines 253.65 and 326.1 nm, respectively perturbed by inert gases (Xe, Kr, Ar and Ne) had been carefully studied over a wide spectral range. Using the point of the maximum temperature dependence {delta}{nu} {sub m} in each case, we are able to calculate the position of the ground state potential R {sub m} using a simple formula.
The third list of objects in the Second Byurakan Spectral Sky Survey is presented. The list contains 94 objects and 12 blue stars. The data given include the equatorial coordinates to within a minute of arc for the epoch 1950, the angular dimensions in seconds of arc, and visual estimates of the blue apparent magnitude B. The objects are described, giving their morphological and spectral features and approximate values of the red shifts of the galaxies. The distribution of the objects in the survey region, which is centered on right ascension 08h00m, declination +59 deg 00 arcmin, with respect to their types is given. Six close binary systems are found among the selected galaxies.
Cyclic spectral analysis is a signal processing technique designed to deal with stochastic signals whose statistics vary periodically with time. Pulsar radio emission is a textbook example of this signal class, known as cyclostationary signals. In this paper, we discuss the application of cyclic spectral analysis methods to pulsar data, and compare the results with the traditional filterbank approaches used for almost all pulsar observations to date. In contrast to standard methods, the cyclic spectrum preserves phase information of the radio signal. This feature allows us to determine the impulse response of the interstellar medium and the intrinsic, unscattered pulse profile directly from a single observation. We illustrate these new analysis techniques using real data from an observation of the millisecond pulsar B1937+21.
Given a double complex $X$ there are spectral sequences with the $E_2$ terms being either H$_I$ (H$_{II}(X))$ or H$_{II}($H$_I (X))$. But if $H_I(X)=H_{II}(X)=0$ both spectral sequences have all their terms 0. This can happen even though there is nonzero (co)homology of interest associated with $X$. This is frequently the case when dealing with Tate (co)homology. So in this situation the spectral sequences may not give any information about the (co)homology of interest. In this article we give a different way of constructing homology groups of $X$ when H$_I(X)=$H$_{II}(X)=0$. With this result we give a new and elementary proof of balance of Tate homology and cohomology.
We have developed efficient spectrally selective infrared (IR) emitters that can be utilized for thermophotovoltaic (TPV) power generation by using stainless steel (SUS304) substrates coated with b- FeSi2 thin films. To develop spectrally selective emitters, we theoretically propose antireflection (AR) coatings consisting of a single layer of a dielectric material having a high refractive index (~5) and are appropriate for use with metals such as stainless steels in the IR region. This type of AR coating is fabricated by sputtering a b- FeSi2 thin film on a polished SUS304 substrate. The reflectance in the IR region is successfully reduced to less than 10%. In addition, the AR properties are stable even at 700 K in air. Therefore, metals with AR coatings of b- FeSi2 can be applied to IR em...
Momentum- and speed-dependent Maxwell-Boltzmann equilibrium distributions have been derived for tachyons and compared with the corresponding relativistic distributions. This is followed by a calculation of the mean, most probable and r.m.s. speeds for both the relativistic and tachyonic distributions. The ideal gas of tachyons is discussed, including calculations of the internal energy and entropy. In each case a comparison is made with the corresponding bradyonic results. It is found that tachyons behave just like bradyons in the high-temperature limit, but have markedly different behaviour at low temperatures.
A high-speed light-Diesel engine with direct injection has been developed by the Institute of Combustion Engines, Graz. Thanks to light construction throughout, exhaust gas supercharger and noise-reduced composition a Diesel engine could be built that is comparable to Otto-cycle engines as regards performance, weight, aggregate size and noise production but far superior to these with respect to fuel consumption and exhaust gas emission.
This study evaluated the heat strain induced by six configurations of a new modular body armor (MBA) design. Tests were conducted in two environments differing only by wind speed. The environments were 40 deg C (104 deg F), 20% rh, wind speeds 1.0 msec-1 ...
Experimental investigations were performed to assess the effects of different shaped obstructions on flame propagation in a rectangular confinement, 235 mm in height, with a 1000 x 950mm cross section and a large top-venting area of 1000 x 320mm. Four different single obstacles were used: rectangular, cylindrical, triangular, and square cross-sections with blockage ratios of 5 and 10%. Temporally resolved flame front images were recorded by a high-speed video camera to investigate the interaction between a propagating flame and the obstacle. The local flame displacement speeds and their probability density functions (pdfs) were obtained for the different obstacles. Before the freely propagating flame impinges on the obstacle, the flame propagation speed remains close to the laminar burning velocity, regardless of the obstacles used. As the propagating flame impinges on the obstacle, the local propagation ...
Two major developments have given impetus to wider adoption of variable-speed turbine/generators in hydroelectric plants, both essentially environmental: (1) the need for stream-bed stability below river dams, and (2) the need to minimize fish damage. Also, the need to stabilize pumped-storage and generating efficiencies to match extreme changes in head levels has been a driving force. Variable-speed operation in hydro applications is relatively new to North America. In other parts of the world, it has been used in pumped-storage plants since 1971. In the US, and increasing potential exists for variable-speed hydro, considering the 30 pumped-storage plants already in operation and several river plants struggling with high head fluctuations--including four at stations operated by the Bonneville Power Administration. Several modifications to hydro-plant hardware and operating procedures are actively being considered at ...
Pellet injectors are needed to fuel long pulse tokamak plasmas and other magnetic confinement devices. For this purpose, an apparatus has been developed that forms 1.3-mm-diam pellets of frozen deuterium at a rate of 40 pellets per second and accelerates them to a speed of 1 km/s. Pellets are formed by extruding a billet of solidified deuterium through a 1.3-mm-diam nozzle at a speed of 5 cm/s. The extruding deuterium is chopped with a razor knife, forming 1.3-mm right circular cylinders of solid deuterium. The pellets are accelerated by synchronously injecting them into a high speed rotating arbor containing a guide track, which carries them from a point near the center of rotation to the periphery. The pellets leave the wheel after 150/sup 0/ of rotation at double the tip speed. The centrifuge is formed in the shape of a centrifugal catenary and is constructed of high strength KEVLAR/epoxy composite. ...
Better properties of magnesium make it a natural choice for use as an anode material in rechargeable batteries. However, the magnesium alloy thin sheets used in rechargeable batteries were produced by ingot casting and rolling. That technology was so complex and the cost was high. Rapidly solidification by melt spinning is an effect way to solve that problem. In this paper, the technology of rapidly solidified (RS) ribbons in Mg-3%Al-1%Zn-0.2%Mn alloy has been investigated using melt spinning technique. The effect of wheel speed on thickness and microhardness of the ribbons is presented. Microhardness is found to increase with the wheel speed. Rapidly solidification leads to small grains (1{proportional_to}2 {mu}m). The plasticity of the ribbons was well. The quantity of Mg{sub 17}Al{sub 12} decreases with the increase in wheel speed. When the wheel speed reaches 1600 rpm, no Mg{sub 17}Al{sub 12} phase ...
The wind speed distribution and wind energy potential are investigated in three selected locations in Oyo state using wind speed data that span between 12 and 20 years measured at 10 m height. In addition, the performance of selected small to medium size wind turbines in these sites were examined. The annual energy output and capacity factor for these turbines were determined. It was found that the monthly mean wind speeds in Oyo state ranges from 2.85 m/s to 5.20 m/s. While the monthly mean power density varies between 27.08 W/m2 and 164.48 W/m2, while the annual mean power density is in the range of 67.28 W/m2 and 106.60 W/m2. Based on annual energy output, wind turbines with cut-in wind speed of about 2.5 m/s and moderate rated wind speeds will be best suited for all the sites.
We study the high-energy emission of the Galactic black hole candidate GX 339-4 using INTEGRAL/SPI and simultaneous RXTE/PCA data. By the end of January 2007, when it reached its peak luminosity in hard X-rays, the source was in a bright hard state. The SPI data from this period show a good signal to noise ratio, allowing a detailed study of the spectral energy distribution up to several hundred keV. As a main result, we report on the detection of a variable hard spectral feature (>150 keV) which represents a significant excess with respect to the cutoff power law shape of the spectrum. The SPI data suggest that the intensity of this feature is positively correlated with the 25 - 50 keV luminosity of the source and the associated variability time scale is shorter than 7 hours. The simultaneous PCA data, however, show no significant change in the spectral shape, indicating that the source is not undergoing a canonical ...
The wavenumber-frequency spectral densities of turbulent wall pressure fluctuations are investigated over a rigid flat plate. Nonlinear Reynolds stress terms of the inhomogeneous Orr-Sommerfeld equation are regarded as a known forcing function. The forcing function is modeled after Bark{close_quote}s hydrodynamic bursting formulation. The inhomogeneous Orr-Sommerfeld equation is solved by the method of Eckhaus in terms of discrete homogeneous solutions. The method of Eckhaus is then extended and proved for the continuous Orr-Sommerfeld eigenfunctions. Turbulent wall pressure fluctuations in terms of wavenumber-frequency spectral densities are numerically computed and compared to the experimental results of Martin as well as to his transformation of Blake{close_quote}s data fitted to a modified Corcos model. The wavenumber-frequency spectral densities numerically computed from the discrete eigenfunctions compared well with ...
The classical theory of collisional broadening and shift parameters (?, ?) of an isolated spectral line was used to obtain simple analytical formulas for calculating both ? and ?. These formulas were obtained on the assumption that the short range interaction is effective only in the broadening while the long range is effective in the shift of the spectral line. These parameters ? and ? depend on the limiting phase shifts responsible for broadening ?b and shift ??. It was found that the values of ?b and ?? are not equal to each other as was proposed by Weisskopf ?b=??=1. The maximum and average values of ?b (?bmax, ?bav) and ?? (??max, ??av) were obtained by numerical evaluation, using different inverse power potentials. By introducing these parameters into the approximated formulas for ? and ? using Van der Waals and Lennard-Jones potential, it was found that the results of calculations for (? and ?) with different atomic transitions perturbed ...
We report on recent inter-calibration studies featuring Swift's Burst Alert Telescope (BAT) and Fermi's Gamma-ray Burst Monitor (GBM) based upon correlated observations of GRBs 080804 and 080810, via their resultant joint spectral analysis. Swift's intrinsic multi-wavelength instrumentation and dynamical response complement Fermi's superior energy range. The addition of BAT's spectral response will (i) facilitate in-orbit GBM detector response calibration, (ii) augment Fermi's low energy sensitivity, (iii) enable ground-based follow-up efforts of Fermi GRBs, and (iv) help identify a subset of GRBs discovered via off-line GBM data analysis, for an annual estimate of ~30 GRBs. The synergy of BAT and GBM augments previous successful joint spectral fit efforts by enabling the study of peak photon energies (Epeak), while leveraging the over eleven energy decades afforded by Fermi's Large Area Telescope (LAT), in conjunction with ...
Microbes in nature frequently function as members of complex multitaxon communities, but the structural organization of these communities at the micrometer level is poorly understood because of limitations...Full Text Available
Spectral line intensity data are presented for ionized hydrogen regions in the giant spiral galaxy M101. The influence of interstellar extinction is assessed and electron temperatures of the gas clouds are derived.
The latest-generation cochlear implant devices provide many deaf patients with good speech recognition in quiet listening conditions. However, speech recognition deteriorates rapidly as the level of...Full Text Available
This is a brief overview of researches of Dmitry Petrovich Zhelobenko (1934--2006). He is the best known for his book "Compact Lie groups and their representations" and for the classification of all irreducible representations of complex semisimple Lie groups. We tell also on other his works, especially on the spectral analysis of representations.
A histidine kinase protein (Cph1) with sequence homology and spectral characteristics very similar to those of the plant phytochrome has been recently identified in the cyanobacterium Synechocystis...Full Text Available
Laser frequency stabilization giving a 500-Hz Allan deviation for a 2-ms integration time with drift reduced to 7 kHz/min over several minutes was achieved at 1536 nm in the optical communication band. A continuously regenerated spectral hole in the inhomogeneously broadened "4I_1_5_/_2(1)#->#"4I_1_3_/_2(1) optical absorption of an Er"3"+:Y_2SiO_5 crystal was used as the short-term frequency reference, while a variation on the locking technique allowed simultaneous use of the inhomogeneously broadened absorption line as a long-term reference. The reported frequency stability was achieved without vibration isolation. Spectral hole burning frequency stabilization provides ideal laser sources for high-resolution spectroscopy, real-time optical signal processing, and a range of applications requiring ultra-narrow-band light sources or coherent detection; the time scale for stability and the compatibility with spectral hole ...
A light-sensitive vitamin B12 derivative has been extracted from the adult cestode, Spirometra mansonoides. This corrinoid was identified as the cobamide coenzyme, adenosylcobalamin, by its chromatographic, chemical, and spectral properties. PMID:1003284
An electroencephalogram (EEG) signal is extremely nonstationary, highly composite and very complex, all of which reflects the underlying integral neurodynamics. Understanding the EEG “grammar”,...Full Text Available
The drug-binding properties of human alpha-foetoprotein (alpha FP) were investigated by a fluorescence-spectral method. Human alpha FP was shown to bind to albumin's site I marker (warfarin, phenylbutazone),...Full Text Available
AbstractX-ray diffraction analysis of pressure-induced structural changes in the Aequorea yellow fluorescent protein Citrine reveals the structural basis for the continuous...Full Text Available
Colour television is examined as an attempt to imitate the human visual system in image formation, spectral sensitivities, adaptation, contrast effects, signal processing, signal modulation, signal...Full Text Available
... days after it burned, using a portable spectroradiometer (704 bands in the range 0.35 to 2.5 mu m) and an infrared thermometer (one band, 6 to 14 mu m). ...
Cross section parameterizations for antiproton production in pp collisions are used to predict the antiproton/proton ratio resulting from a flux of cosmic protons with energy spectral index of 2.6 interacting with a 5 gm/cm/sup 2/ column density of H. (GHT)
PurposeTo establish normative values for macular light sensitivity and to determine the intrasession fluctuation of perimetric responses using the OPKO/OTI microperimeter.Full Text Available
Computer assisted energy-spectral analyses were obtained on EEG recordings of unilateral non-dominant hemisphere ECT-induced seizures using the different pre-ECT anesthetic agents methohexital (Brevital), Innovar, and ketamine (Ketalar). The previously postulated predominance of electrical energy over the stimulated (right) hemisphere early in ECT-induced seizures is confirmed. There appears to be marked reduction in total seizure energy with methohexital anesthesia, whereas ketamine anesthesia appears to be associated with increased overall seizure energy. The greatest right to left energy transfer during the seizure occurred with Innovar anesthesia. PMID:7172456
Available from UMI in association with The British Library. Requires signed TDF. Design of time and correlation windows for non -parametric frequency response estimates. The thesis deals with problems that arise in the field of spectral analysis due to finite observations of input and output records. In particular, it is concerned with the method of applying time and correlation windows in spectral analysis procedures to obtain non-parametric frequency response estimates of open-loop time invariant systems. The thesis reviews and develops the sources of error that arise when frequency response techniques are applied directly to windowed records of input and output data to estimate the frequency response of open loop systems. Having identified the cause of these errors, methods of eliminating or reducing them are studied. The techniques introduced involve the use of differing time windows for the input and output data records. It is shown that ...
Localized corrosion has a stochastic character by nature. This character leads to an observed random behavior: fluctuations of the free potential, fluctuations of the current when a constant potential is maintained. This random signal, which is similar to an electric noise, can be analyzed either in the time domain by counting the events or in the frequency domain by measuring the power spectral density of the electrochemical noise. The experimental techniques developed for investigating the localized corrosion on the probabilistic point of view, i.e., statistical counting and power spectral density measurements, are discussed. Then the experimental results reported in the literature are reviewed in order to see what kind of parameters are accessible and how they can be related to the localized corrosion processes.
We iterate Manolescu's unoriented skein exact triangle in knot Floer homology with coefficients in the fraction field of the group ring (Z/2Z)[Z]. The result is a spectral sequence which converges to a stabilized version of delta-graded knot Floer homology. The (E_2,d_2) page of this spectral sequence is an algorithmically computable chain complex expressed in terms of spanning trees, and we show that there are no higher differentials. This gives the first combinatorial spanning tree model for knot Floer homology.
A general space- and energy-dependent formalism is developed in order to analyze zero-power neutron noise experiments in fast reactor systems. A generalized dispersion equation is combined with theoretical expressions for the experimentally measured power spectral density and variance-to-mean ratio which makes it possible to express these quantities in terms of a double moment of the Laplace and Fourier transformed Green's function of a slowing-down operator rather than those of the full Boltzmann operator. Several spatial approximations are analyzed in the context of the general formalism. In each case, the power spectral density and variance-to-mean ratio are written in terms of an appropriate fast reactor dispersion law for the medium which can be calculated from the solution to a simple slowing-down equation. The resultant expression for the power spectral density are analyzed for various combinations of ...
A pump down model for a vacuum chamber with a reversibly adsorbed phase is presented. The outgassing equation which predicts the variation of coverage at the wall surface of a vacuum chamber with time is derived. Then the measured and the true outgassing rates are defined. The theoretical measured outgassing rate shows only a very weak dependence for pumping speed. This prediction is opposite to the experimental result that the measured outgassing rate depends significantly on pumping speed. It is discussed that the experimental measured outgassing rate must be described as the product of the effective pumping speed and the measured pressure in the pumped chamber, in which the measured pressure is equivalent to the equilibrium pressure of the wall surface described by the equilibrium adsorption isotherm as a function of the shifted surface coverage {theta}-{delta}{theta} by a small coverage {delta}{theta} from the coverage ...
This paper presents a new method to improve sensorless performance of matrix converter drives using a parameter estimation scheme. To improve low-speed sensorless performance, the non-Iinearities of a matrix converter drive such as commutation delays, turn-on and turn-off times of switching devices, and on-state switching device voltage drop is modelled using PQR transformation and compensated using a reference current control scheme. To eliminate the input current distortion due to the input voltage unbalance, a simple method using PQR transformation is also presented. The proposed compensation method is applied for high performance induction motor drives using a 3 kW matrix converter system without a speed sensor. Experimental results are shown to illustrate the feasibility of the proposed strategy.
In order to realize simultaneous reduction of NO{sub x} and Particulate emissions, effects of combustion chamber geometry were investigated in a high speed direct-injection diesel engine. The reentrant combustion chambers with different throat diameter were compared in terms of engine performance, combustion characteristics and emissions such as NO{sub x}, particulate and THC. The phenomena of combustion process were also observed with endoscopic high speed photography. The results showed that when the throat diameter of a reentrant combustion chamber was reduced to an extent, NO{sub x} and particulate decreased simultaneously due to retarded injection timing and the intensified squish. (author)
The factors influencing premixed burning and the importance of premixed burning on the exhaust emissions from a small high-speed direct-injection diesel engine were investigated. The characteristics of premixed and diffusion burning were examined using a single-zone heat-release analysis. The mass of fuel burned in premixed combustion was found to be linearly related to the product of engine speed and ignition-delay time and to be essentially independent of the total amount of fuel injected. Accordingly, the premixed-burned fraction increased with increasing engine speed, with decreasing fuel-air ratio and with retarding injection timing. The hydrocarbon emissions did not correlate well with the premixed-burned fraction. In contrast, the oxides of nitrogen emissions were found to increase with decreasing premixed-burned fraction, indicating that diffusion burning, and not premixed burning, is the primary source of oxides of ...
Recent work has been carried out on development of isotope wear analysis and optical and eddy current technologies to provide bearing wear measurements and real time monitoring of shaft speed, shaft axial displacement and shaft orbit of the Orbit Transfer Vehicle hydrostatic bearing tester. Results show shaft axial displacement can be optically measured (at the same time as shaft orbital motion and speed) to within 0.3 mils by two fiberoptic deflectometers. Evaluation of eddy current probes showed that, in addition to measuring shaft orbital motion, they can be used to measure shaft speed without having to machine grooves on the shaft surface as is the usual practice for turbomachinery. The interim results of this condition monitoring effort are presented.
Dynamic stability enhancement of composite mode oscillations of interconnected power systems by means of a hybrid power system stabilizer is discussed here. The proposed Hybrid PSS is of a two-level structure composed of a local PSS for local mode and a global PSS for inter-area mode damping. Here, the input of the global stabilizer is the center of inertia speed deviation of slow-coherent generators. The paper is focused on the practical considerations in implementation of the proposed stabilizer. First, the optimum allocation of this stabilizer is discussed. The authors introduce an index of mode-input-assignability, by which the best sites of the stabilizer can be identified. Next, for practical applications, an estimation method for the approximation of the input of the global PSS is introduced. An approximated value of the center of inertia speed is obtained from a suitable combination of the rotor speed data of a few ...
In this study, usage of a variable speed refrigeration system in latent heat thermal energy storage (LHTES) system is investigated to increase energy storage efficiency. Four different compressor speed control cases are compared to obtain a constant heat transfer fluid (HTF) temperature at the inlet of the energy storage tank. These control cases are (i) control with evaporation temperature, (ii) control with ethylene glycol temperature at the outlet section of evaporator, (iii) control with suction pressure of the compressor and (iv) on/off control. By means of the experimental analysis the best control strategy is obtained as control with Case (ii), in terms of stability of inlet temperature of heat transfer fluid, variations of energy efficiency of LHTES and coefficient of performance (...
An organically modified montmorillonite (MMT) was compounded with polybutylene terephthalate (PBT) in a twin-screw extruder. The organoclay PBT nanocomposites were then injection molded by conventional and microcellular methods. Nitrogen was used as the blowing agent. The effect of organoclay content, organoclay size (8 and 35mm), and speed of the screw (80 and 100rpm) on the mechanical and thermal properties were investigated. The results showed that when the MMT content was 1.0wt.%, the nanocomposites have maximum tensile strength, wear resistance, and cell density. Moreover, the larger the particle size, the greater the tensile strength. The screw speed during compounding also affected the mechanical strength. The higher speed of the screw increased the tensile strength of the nanocompo...
In this paper, a complete solution of the steady-state Newton-Euler equations describing the motion of the balls in high speed thrust bill bearings is presented. Kinematic equations are derived and used as ancillary equations to obtain the numerical solution of the Newton-Euler equations. This differs from previously reported work where extraneous assumptions (instead of kinematic analysis) are used to allow solutions of these equations. It is shown that the no-slip condition for the ball motion reported in the literature is based on an unnecessary assumption. The correct form of the condition is developed and used in the analysis of the ball motion. The analysis shows the importance of contact angle on both ball motion and contact force. An approximate theory is then developed for determining the optimum contact angle that would result in minimum contact force in high speed ball bearings. The results are compared with experimental data, and ...
'Full text:' The use of fuel cell technology in military applications will depend on safe, high energy density systems being developed. An important part of using this technology is also the development of alternative hydrogen producing fuels with high energy densities and are easy to transport. Fuel cells are now a very large R and D effort for several military applications around the world. The major reason is because of the high power demands needed requires electrical energy sources that far exceed the capabilities of batteries currently being fielded for portable applications. Fuel cells are regarded as highly efficient, tactical energy converters that can be adapted for wide range of power requirements. They are potentially the lowest weight power source when coupled with batteries or capacitors to form hybrid systems. Generally electrical power is needed to support a number of applications from ultra-high power for electrical pulses (radios, sensors) to ...
A 2-stage cold (non-tritium) PMR system was tested with the ITER mix in61 days of continuous operation. No decrease in performance was observed over the duration of the test. Decontamination factor (DF) was found to increase with decreasing inlet rate. Decontamination factors in excess of 1.4 {times} 10{sup 5} were obtained, but the exact value of the highest DF could not be determined because of analysis limitations. Results of the 61-day test were used to design a 2-stage PMR system for use in tritium testing. The PMR system was scaled up by a factor of 6 and built into a glovebox in the Tritium Systems Test Assembly (TSTA) of the Los Alamos National Laboratory. This system is approximately 1/5th of the expected full ITER scale. The ITER mix was injected into the PMR system for 31 hours, during which 4.5 g of tritium were processed. The 1st stage had DF = 200 and the 2nd stage had DF = 2.9 {times} 10{sup 6}. The overall DF = 5.8 {times} 10{sup 8}, which is greater than ITER ...
A 2-stage cold (non-tritium) PMR system was tested with the ITER mix in 61 days of continuous operation. No decrease in performance was observed over the duration of the test. Decontamination factor (DF) was found to increase with decreasing inlet rate. Decontamination factors in excess of 1.4x10"5 were obtained, but the exact value of the highest DF could not be determined because of analysis limitations. Results of the 61-day test were used to design a 2-stage PMR system for use in tritium testing. The PMR system was scaled up by a factor of 6 and built into a glovebox in the Tritium Systems Test Assembly (TSTA) of the Los Alamos National Laboratory. This system is approximately 1/5"t"h of the expected full ITER scale. The ITER mix was injected into the PMR system for 31 hours, during which 4.5 g of tritium were processed. The 1"s"t stage had DF =200 and the 2"n"d stage had DF=2.9x10"6. The overall DF=5.8x10"8, which is greater than ITER requirements. 3 refs., 10 figs.
Full text. Here we present a status report of the Schenberg antenna, which started commissioning runs in September 2006 under the full support of FAPESP. In its first commissioning runs we tested three preliminary parametric transducer systems, which did not achieve a high enough performance for placing the antenna sensitivity in the range of the calibrator capacitor. Instead of improving the calibrator, making it capable of introducing a larger input force, we decided to go to a radical upgrading operation: replacing the three transducers for a complete set of six transducers, with better sensitivity and arranged according to the truncated icosahedron configuration, plus two extra ones; starting to install the dilution refrigerator; installing wires, cables, and amplifiers for the complete set of transducer circuits; and a new suspension and vibration isolation system for the cabling and microstrip antennas. We also have been developing a new set of transducers, microwave oscillators, ...
Porous carbon with high surface area and pore volume was prepared by a reverse replication process and its toluene equilibrium adsorption behavior was investigated. The preparation process of the porous carbon was composed of following sub-processes in series: synthesis and template preparation of silica gel, impregnation and polymerization of DVB monomer in silica template, carbonization of DVB polymer in a silica-polymer composite, and HF-assisted selective etching of silica in carbon-silica composite, The prepared porous carbon was nano porous and had ultrahigh specific surface area (2007 m{sup 2}/g) and large pore volume (3.07cm{sup 3}/g). The nanoporous carbon showed rapid toluene adsorption rate and good toluene adsorption capacity, compared with a commercial Y-type zeolite, In the present study, a reverse replication process to prepare nanoporous carbons will be introduced and its application potential as a gas adsorbent will be discussed. (author). 17 ...
Abstract: We report for the selective-area chemical synthesis of semiconductor single-crystal organic nanowires of silver-tetracyanoquinodimethane (Ag-TCNQ). Straight and smooth Ag-TCNQ nanowires can be produced and patterned on micrometer and nanometer scale on silicon substrates covered with a thin layer of Ag film through the reaction of TCNQ and Ag in a simple gas-solid chemical reaction process. Ag-TCNQ nanowires are characterized by UV-vis, IR and Raman spectroscopy, respectively. The Ag-TCNQ nanowires grows preferentially along the [100] direction of strong - stacking of Ag-TCNQ molecules. Nanodevices based on these nanowires are fabricated using focus ion beam (FIB) technique. Electrical properties are characterized and I-V hysteresis is observed, which shows memory effect with electrical switching of three orders on-off ratio. These nanowires could be potential for use in optical storage, ultrahigh-density nanoscale memory and logic devices.
Research and development has been performed on photochromic materials expected to be used in ultra-high density recording, high resolution indication and photoswitches. With regard to molecular orientation in the ternary system mixed LB film, the result of structural analysis by XPM spectrum revealed that the acceptor constituent in the LB film is so structured that it is separated and laminated with two other constituents, and that the sensitizer constituent and the donor constituent are not recognized of being separated definitely. Regarding the electron movement reaction in the solid phase system, a photo-current measuring experiment was carried out on the laminated film which is vacuum-deposited with the ternary system comprising of the donor, sensitizer, and acceptor. It was concluded that the observed photo-current reflects the electron movement reaction in the solid phase as it is. For the photo-current in the LB film, increase in the photo-current was ...
Potassium deposition in ultrahigh vacuum on 12-(3-thienyl)dodecanethiol monolayers assembled on gold surfaces has been investigated using X-ray and ultraviolet photoelectron spectroscopies (XPS and UPS). Angle-resolved XPS indicates that initially deposited potassium penetrates the self-assembled monolayer (SAM) and diffuses to the SAM/Au interface. Even after large metal doses, the presence of thiophene ring valence electronic states in the UPS spectra confirms that most of the thiophene rings (at the SAM/vacuum interface) are not covered by potassium. The binding energy shifts of the thiophene ring valence states and the C1s and thiophene S2p peaks, referenced to the Fermi level, are due to the work function changes of the gold substrate. This indicates that these electronic states are pinned to the vacuum level, in contrast to the thiolate S2p orbital, which is pinned to the Fermi level. For large potassium doses, the appearance of new features in the UPS ...
Samples of ultra-high molecular weight polyethylene (UHMWPE) and nylon 66, of grades suitable for use in medical prostheses, were subjected to irradiation using a /sup 60/Co source. The effects of a 10 Mrad dose on percentage crystallinity, tensile behaviour and dynamic mechanical response were established 3 days after irradiation at intervals over a one year period. Crystallinity in UHMWPE was found to increase progressively during this period with consequent changes in mechanical behaviour. It is proposed that the observed ageing process arises from the breakdown of metastable groups in the polymer, which are formed on irradiation, with consequent release of long inter-lamella tie chains. This removes an inhibition to crystal perfection processes, which can occur at room temperature in polyethylene. Infra-red spectroscopic evidence supports the proposal that the metastable species is peroxy or hydroperoxy and that this decomposes on ageing to a carbonyl group, ...
Fe-Ni-Mn martensitic steels are one of the major groups of ultra-high strength steels that have good mechanical properties and ductility in as annealed condition but they suffer from severe inter-granular embitterment after aging. In this paper, the effect of heavy shaped cold rolling and wire drawing on the mechanical properties of Fe-Ni-Mn steel was investigated. This process could provide a large strain deformation in this alloy. The total strain was {epsilon} {approx}7. Aging behavior and tensile properties of Fe-10Ni-7Mn were studied after aging at 753 K. The results showed that the ultimate tensile strength and ductility after cold rolling, wire drawing and aging increased up to 2540 MPa and 7.1 %, respectively, while the conventional steels show a premature fracture stress of 830 MPa with about zero ductility after aging.
Fe-Ni-Mn martensitic steels are one of the major groups of ultra-high strength steels that have good mechanical properties and ductility in as annealed condition but they suffer from severe inter-granular embitterment after aging. In this paper, the effect of heavy shaped cold rolling and wire drawing on the mechanical properties of Fe-Ni-Mn steel was investigated. This process could provide a large strain deformation in this alloy. The total strain was #epsilon# #approx#7. Aging behavior and tensile properties of Fe-10Ni-7Mn were studied after aging at 753 K. The results showed that the ultimate tensile strength and ductility after cold rolling, wire drawing and aging increased up to 2540 MPa and 7.1 %, respectively, while the conventional steels show a premature fracture stress of 830 MPa with about zero ductility after aging.
Measurements of the Kapitza conductance to liquid helium II across the (100) surface of single crystals of copper are presented. The temperature range of these measurements was 1.6-- 2.1 K. The sample surfaces were subjected to several different treatments. Some surfaces were cleaned by low-energy argon ion bombardment, annealed in an ultrahigh-vacuum system, and preserved under vacuum until purified liquid helium was admitted. Other surfaces were intentionally damaged by machining and/or exposure to the atmosphere. The conductance after these latter treatments was found to be about a factor of three higher than that of the more ideally cleaned and annealed surfaces, and a significant difference in the temperature dependence of the conductance was also observed. Conductances were reproducible for similarly treated surfaces and correlated with surface damage determined by x-ray diffraction. The relationship of these results to the numerous current theories of the ...
Ti-15Mo-2.7Nb-3Al-0.2Si (Timetal-21S), a metastable #beta#-titanium alloy, is a candidate material for titanium matrix composite structures in hydrogen-fueled hypersonic planes because of its excellent formability and adequate mechanical properties in the 500--800 C temperature range. The alloy is strengthened through the precipitation of fine #alpha# particles in the #beta# matrix. The mechanical properties and microstructures are controlled by a solutionizing/aging heat treatment. A major concern in using titanium alloys in hydrogen service is the embrittlement caused by the precipitation of hydrides. It is believed that the large solubility of hydrogen in the #beta#-phase would preclude the precipitation of hydrides in Beta titanium alloys, especially at low hydrogen pressures. However, depending on the hydrogen content, a shift in the ductile/brittle transition temperatures to levels much higher than room temperature has been reported for Timetal-21S alloy. The objective of the ...
Gamma-ray burst (GRB) is one of the candidates of high-energy cosmic-ray acceleration sites. They may be also ultra-high-energy (above 3 EeV) cosmic-ray (UHECR) sources. In this paper, we discuss possibilities and implications of high-energy cosmic-ray acceleration in GRBs. (1) First, we show that not only protons but also heavier nuclei can be accelerated up to ultra-high energies in both usual high-luminosity (HL) and low-luminosity (LL) GRBs by using the Geant4. LL GRBs may also make a significant contribution to the observed UHECR flux if they form a distinct population, and we investigate cosmic-ray acceleration in LL GRBs in detail. (2) Second, we discuss implications of the GRB-UHECR hypothesis (and Hypernova-UHECR hypothesis) to cosmic-ray astronomy. HL GRBs and LL GRBs will lead to different source number densities as UHECR sources, so that the determination of the number density of UHECR sources and strength of the mean extragalactic magnetic field (EGMF) ...
The current--density profile of a focused ion beam (FIB) has a central peak accompanied by broader ``wings`` that, while unimportant in lithographic applications, can lead to unwanted effects during an implantation operation. The origin of the wings, and hence the best way to minimize them, is not clear and needs further study. We have measured the line profiles of several of the ions available in our FIB machine as a function of a number of variables, under ultrahigh vacuum (UHV) conditions. No effects are observed from changes in emission current or deliberate defocusing of the objective lens. There are some changes with beam aperture and/or current, but the biggest differences seem to be associated with a change of source type and hence, possibly, with a change in the source/extractor configuration or in the alloy and the emission process. The wing amplitudes are appreciably lower than many previously observed, and their profiles, at least for the lighter ions ...
The current--density profile of a focused ion beam (FIB) has a central peak accompanied by broader ''wings'' that, while unimportant in lithographic applications, can lead to unwanted effects during an implantation operation. The origin of the wings, and hence the best way to minimize them, is not clear and needs further study. We have measured the line profiles of several of the ions available in our FIB machine as a function of a number of variables, under ultrahigh vacuum (UHV) conditions. No effects are observed from changes in emission current or deliberate defocusing of the objective lens. There are some changes with beam aperture and/or current, but the biggest differences seem to be associated with a change of source type and hence, possibly, with a change in the source/extractor configuration or in the alloy and the emission process. The wing amplitudes are appreciably lower than many previously observed, and their profiles, at least for the lighter ions ...
The UTST (University of Tokyo Spherical Tokamak) device was constructed for the purpose of exploring the formation of ultra-high beta ST (Spherical Tokamak) plasma using the double null plasma merging method. When two plasmas merge together to form a single plasma, magnetic field lines reconnect, and the magnetic field energy is converted to the plasma kinetic energy, increasing the plasma beta. The merging start-up has been demonstrated in the TS-3/4, START and MAST devices using coils inside the vacuum vessel and TS-3 plasma obtained 50% beta. In order to demonstrate the start-up in a more reactor relevant situation, UTST has all poloidal field coils outside the vacuum vessel. The first plasma experiment on the UTST was performed from December, 2007. In the result, the plasma obtained 10 kA by using only outer PF coils and single ST was generated at the lower area (z=-0.3 - -1.0[m]) close to a washer gun. This result suggests that another washer gun on the top of ...
The growth of epitaxial MnO(100) and MnO(111) layers on Pd(100) surface has been investigated by spot-profile analysis low-energy electron diffraction, dynamic atomic force microscopy, photoemission and high-resolution electron energy loss spectroscopy, and density functional theory. We have found that despite the large lattice mismatch to the Pd(100) substrate, the MnO(100) layers are kinetically stabilized at low temperatures (?350 deg. C) and at oxygen pressures between 2x10-7 and 5x10-7 mbar. Annealing in ultrahigh vacuum at 650 deg. C or, alternatively, deposition of manganese metal in oxygen pressure -7 mbar causes the transformation of the MnO(100) to a polar MnO(111) surface, which is decorated by triangular pyramids with (100) side facets. It is suggested that the growth of MnO(111) layers is energetically preferred over MnO(100) due to the epitaxial stabilization at the metal-oxide interface.
CuAg core-shell nanoparticles are synthesized by ultra-high vacuum thermal evaporation. We show on this system how the Energy-Filtered Transmission Electron Microscopy (EFTEM) technique allows one to improve the characterization by precisely pointing out the formation of core-shell arrangements in bimetallic nanoparticle assemblies. A criterion to measure the shell thickness from EFTEM images on unique core-shell nanoparticles is defined, that can be used for core-shell nanoparticles of any sizes, with shell thicknesses over 1 nm. It is based on the intensity variation along a line drawn across a core-shell nanoparticle on a EFTEM image. This criterion has been validated by a close comparison of the shell thickness measurements performed in this work and the ones obtained by acoustic micro-Raman spectroscopy. Using this criterion, we report a strong correlation between the size of the Cu cores and the formation of the core-shell arrangements in the nanoparticle ...
Negative ion electrospray ionization (ESI) coupled with high field Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) allows for the direct detection of acidic NSO compounds in petroleum. The technique requires no chromatographic separation, is able to distinguish 18 different compound classes (e.g., neutral nitrogen, carboxylic acids and oxygenates), and can identify {approx}14,000 distinct masses by ultra-high mass resolution and mass accuracy. We previously studied three crude oils from different geological origins [Organic Geochemistry 33 (2002b) 743-759]. Here, we expand our research by comparing two source-equivalent Smackover oils of different levels of thermal maturity. We observe clear differences in the distribution of NSO compound classes, types (number of rings plus double bonds within a class), and number of alkyl carbons. With increasing thermal stress, the relative amount of sulfur and oxygen containing compounds decreases, ...
The Abrasive Waterjet Cutting process was evaluated to determine if the equivalent could be utilized for cutting uranium metal at the Feed Materials Production Center (FMPC). In the process, a thin stream of ultrahigh pressure water carried grit material through a designated piecepart. In order to be acceptable for use at the FMPC, the equipment must be cost effective, minimize waste, and be adaptableto operating in an enclosure, and improve health and safety conditions. Observation of the cutting process showed that health and safety aspects could be optimized with an enclosed ventilated system. Also the equipment can be easily automated. The cutting action produced sparks similar to the sparks caused by a grinding operation. The sparks are captured in a water container under the workpiece that not only catches the sparks, but also serves to dissipiate the stream of water and residues produced by the cut. Metallographic tests performed on the cut surface of the ...
The latest inclined mine winder started operation in April, 1995 at the Kushiro Mining Station of Taiheiyo Coal Mining Co. A permanent magnet synchronous motor, a cycloconverter, and H{sub {infinity}} control are employed to complete the latest inclined mine winder. The winder is the world`s longest and fastest inclined mine winder, and the torque of the permanent magnet synchronous motor is the largest in the world. A report is made on the driving system placing emphasis on the points considered in the design. The gallery has the length of world`s longest 6,626m and the average gentle inclination of 6 degree. The worker transport car runs at the world`s fastest speed of 420m/min from the mouth to the bottom of the pit, making a round trip in 40 minutes. Speed is adjusted smoothly by the cycloconverter, and the car arrives at the destination safely in a short time due H{sub {infinity}} controlling. By the application of H{sub {infinity}} ...
The control problem associated to a class of horizontal-axis fixed-pitch variable-speed low-power wind energy conversion systems, working in the partial load region, consisting in the energy conversion maximization, is approached here under the assumption that the wind turbine model and its parameters are poorly known. Using a new approach derived from the optimum seeking methods category, generically called Maximum Power Point Tracking (MPPT), the proposed control solution aims at driving the average position of the operating point near to optimality. Instead of inducing sinusoidal search signals, the wind turbulence is here used as search disturbance. The high-speed shaft's average rotational speed is slowly adjusted using the Fast Fourier Transform processing of some available measures from the system as an estimate of the operating point's position/distance to optimality. Numerical simulations are used ...
1. At high running speeds, the step frequency becomes lower than the apparent natural frequency of the body's bouncing system. This is due to a relative increase of the vertical component of the muscular...Full Text Available
We show that, in addition to radiation travelling at the speed of light, QED theory predicts a second type of radiation with an infinite velocity. We also show that charge, as it appears in the Dirac equation, may have a triune nature.
The ratio of particle velocity to translation speed exceeds 1 for 98% of .... The westward movement of the meandering jet and eddy system transports nutrient- rich ...... J. Hydrometeor., 4, 1044-1066. Gedney, N., P. M. Cox, H. Douville, ...
N alpha-Acetylenkephalin carboxypeptidase was co-purified with N-acetyltyrosine deacetylase from monkey kidney. Almost 90% of the activity from the homogenate was recovered in a high-speed supernatant...Full Text Available
This paper describes high speed rolling and gauge control in cold tandem mill for ultra-thin gauge strip at the Chiba Works of Kawasaki Steel Corporation. To improve the plate-out property of rolling oil, cationic polymeric coagulant was prepared. Rolling oil with cohesion independent of inorganic inclusions or phosphatide was developed, to improve the lubrication for cold rolling, remarkably. In addition, a low-cost Ti-enhanced work roll having high wear resistance and excellent grindability was developed. Rolling can be conducted at the optimal rolling roughness and operation can be performed at the highest rolling speed independent of the rolling treatment amount. Rolling speed at 2800 m/min was confirmed by developing the rolling oil with excellent lubrication and the work roll having high wear resistance. For the improvement of strip thickness accuracy at the steady state rolling, use of the backup roll as roller ...
This work presents an analysis of the operation of a multi-cylinder, tubro charged, indirect injection diesel engine from a second-law analysis point of view. For this purpose, a single-zone thermodynamic model following the filling and emptying modelling technique is developed. A second-law analysis is performed in all parts of the diesel engine plant, which provides all the existing availability terms and accounts for the evaluation of every component`s irreversibilities. A complete second-law terms tabulation is given for the maximum speed-full load operation case, which is compared with its first-law counterpart. A detailed parametric study is performed in all parts of the diesel engine plant comprising the effects of speed and load on the availability terms in a range that covers the whole operation of the engine under turbocharged action. Various second-law (availability) terms such as indicated and brake work, heat transfer, inlet air, ...
The fact that electric autos have driven over 100 miles without a battery recharge over an urban stop and go course at city driving speeds demonstrates that practical electric cars for city use can be built today.
BackgroundRNA turnover plays an important role in the gene regulation of microorganisms and influences their speed of acclimation to environmental changes. We investigated whole-genome...Full Text Available
The automatic real-time system operating at the LU-10 linac and providing measurements of the parameters such as the beam current (average and pulse values), the electron energy, the linear density distribution of beam current, and also the conveyor speed is described in the paper.
We examined the effect of spatial iconicity (a perceptual simulation of canonical locations of objects) and word-order frequency on language processing and episodic memory of orientation. Participants...Full Text Available
1. The relation of V̇O2 and speed was measured on seven athletes running on a cinder track and an all-weather track. The results were compared...Full Text Available
Experience with visual objects leads to later improvements in identification speed and accuracy (“repetition priming”), but generally leads to reductions in neural activity in single-cell...Full Text Available
Although ultrasound arrays were exploited in photoacoustic imaging to improve imaging speed, ultrasound-array-based optical-resolution photoacoustic microscopy (OR-PAM) has never been achieved...Full Text Available
1. The mechanical power spent to accelerate the limbs relative to the trunk in level walking and running, Ẇint, has been measured at various `constant' speeds (3-33...Full Text Available
Experiments were conducted with a scale model of an amphibious vehicle towed in calm water. Pressure distribution along the submerged bow and hull bottom was determined for a range of vehicle speed. A waterjet system with a bow intake and an axial flow im...
How can the inhabitants of the European Union be brought closer together? One way of doing it is to expand and improve the trans-European railway network and to have interoperable highspeed trains connecting Europe's major centres. (orig.)
The speed of ethylene-induced leaf abscission in cotton (Gossypium hirsutum L. cv LG-102) seedlings is dependent on leaf position (i.e. physiological age). Fumigation...Full Text Available
The modification of a Ford 7600 turbocharged diesel engine to a dual fuel engine using methane as the supplementary fuel has been carried out. The paper describes the preliminary work of dual fuel control. Two systems are examined and their behaviour is presented.
This combined analytical and experimental program is aimed at generating a manual that will permit the design of 3.0 MDN cylindrical roller bearings. The roller bearing analysis will be correlated with the results from a series of bearing tests designed t...
For sufficiently cool remote gases, the cylindrical stretched flame shows classical ignition-extinction behavior. For remote gas temperatures close to the adiabatic flame temperature, the flame response is qualitatively different, with negative flame speed solutions which may be physically accessible.
10 papers are presented with the following titles: coal fueled diesel engine development update at GE transportation systems; features and performance data of Cooper-Bassemer coal-fueled six-cylinder LSB engine; preliminary test data and systems analysis of a high pressure coal fuel processor/engine system concept; study for coal-water-slurry fuel combustion in a high speed diesel engine; design and operation of a medium speed 12-cylinder coal-fueled diesel engine; progress on the investigation of coal water slurry fuel combustion in a medium speed diesel engine: part 5 - combustion studies; injection characteristics of coal-water slurries in medium speed diesel equipment; coal-water slurry spray characteristics of a positive displacement fuel injection system; novel injector techniques for coal-fueled diesel engines; and investigation of break-in wear, ring loading and oil supply configuration effects ...
We explore a possibility that the daily sea-level pressure (SLP) over South Korea responds to the high-speed solar wind event. This is of interest in two aspects: First, if there is a statistical association this can be another piece of evidence showing that various meteorological observables indeed respond to variations in the interplanetary environment. Second, this can be a very crucial observational constraint since most models proposed so far are expected to preferentially work in higher latitude regions than the low latitude region studied here. We have examined daily solar wind speed ${\\rm V}$, daily SLP difference ${\\rm \\Delta SLP}$, and daily ${\\rm \\log(BV^{2})}$ using the superposed epoch analysis in which the key date is set such that the daily solar wind speed exceeds 800 ${\\rm kms^{-1}}$. We find that the daily ${\\rm \\Delta SLP}$ averaged out of 12 events reaches its peak at day +1 and gradually ...
Instrumented treadmills offer significant advantages for analysis of human locomotion, including recording consecutive steady-state gait cycles, precisely controlling walking speed, and avoiding...Full Text Available
OBJECTIVE: To test the hypothesis that perioperative transfusion of allogeneic and autologous red blood cells (RBCs) stored for a prolonged period speeds biochemical recurrence of prostate cancer...Full Text Available
As part of a comprehensive simulation of a prototype locomotive propulsion system, a detailed model has been developed which predicts the dynamic response of an experimental 2-stroke, turbocharged and intercooled diesel engine. Engine fueling and brake torque are computed from regression equations derived from an extensive data base. Corrections are applied to the calculated steady-state torque to account for dynamic deviations of in-cylinder trapped air-fuel ratio from the steady-state value. The engine simulation accurately represents the operation of the turbo-charger, which is gear-driven at low turbocharger speeds, and freewheels through an overrunning clutch when exhaust energy accelerates the turbocharger beyond its geared speed. Engine fueling level, ie, rack, is determined from a dynamic simulation of an electrohydraulic governor which responds to the difference between the desired and the actual engine speeds. The ...
Accurate segmentation of tissue microarrays is a challenging topic because of some of the similarities exhibited by normal tissue and tumor regions. Processing speed is another consideration...Full Text Available
A univibrator and a pulse height discriminator using tunnel diodes and backward diodes are described, along with their applications in pulse shaping and fast coincidence technique. The main advantages achieved are simplicity of design and speed. The characteristics of the two diodes are shown. (auth)
...Track haulage roads. (a) The speed at which haulage equipment is operated should be determined by the condition...elements of the track and the type and condition of the haulage equipment. (b) Track haulage roads should...
The possibility of surface modification of high-speed steel cutting tool by means of vacuum-plasma treatment including ion nitriding in gas plasma followed by the deposition of wear resistant (Ti, Al)N coatings in metal-gas plasma of a vacuum arc discharge is studied. The regularities of nitrided layer formation and the structure of these layers under various operation conditions of cutting tool are investigated. Optimum conditions of vacuum-plasma treatment providing the best wear resistance of cutting are determined
This report describes the design, fabrication, installation and testing of a small variable-speed vertical axis wind turbine (VAWT). This VAWT is unique in its installation using hand tools only; unconventional and simple support system; and variable speed operation under microprocessor control. Initial testing confirmed that the turbine can be controlled by commanded alternator field modulation. Further studies will be directed toward determination of an optimum control algorithm.
This paper reports on the electron current to a Langmuir probe in a moving high-pressure plasma. The plasma is an atmospheric-pressure propane flame, and the probe's speed relative to the plasma is varied from 10 to 30 ms"-"1. The current is linearly dependent on the speed and appears to be comprised of two components - one driven by diffusion and the other by convection. A model is devised which can be used to measure the electron density. By comparing the density computed from this model to that measured from the ion current, it has been possible to measure the electron mobility in the flame gases. The value obtained here is in good agreement with theoretical calculations found in the literature.
The solar powered electric vehicle race began in Arlington, Texas on June 20, 1993 and finished 7 days later in Minneapolis, Minnesota. Thirty four teams from Universities across the United States and Puerto Rico completed the race out of thirty six entries. The race demonstrated the viability of sunlight powered vehicles as the better average daily speeds were in excess of 50 miles an hour. Even in the rain, most average speeds were in excess of 15 miles an hour. Analyzed results, photographs, and project details are included. (GHH)
we report an ultrafast synchrotron x-ray phase contrast imaging study of the primary breakup mechanism of a coaxial air-assisted water jet. We demonstrate that there exist great similarities in the phenomenology of primary breakup with that of the secondary breakup. Especially, a membrane-mediated breakup mechanism dominates the breakup process for a wide range of air speeds. This finding reveals the intrinsic connections of these two breakup regimes and has deep implications on the unified theoretical approach in treating the breakup mechanism of high speed liquid jet.
A rotational speed control, tailored to the Sunflower system requirements, was designed and fabricated in breadboard, preprototype, and prototype configurations. These units were subjected to performance and environmental testing which has led to design improvements. Program efforts have yielded hardware capable of meeting all performance requirements and of operating under all the environmental conditions to which the units were exposed. Attractive design changes were identified and, in some cases, completed. These changes involve improvements in circuitry and packaging, the primary objectives of which are to eliminate startup bias batteries and reduce weight. It is recommended that the reported program be extended to implement these improvements. (auth)
In a treatment system of radioactive waste solution including sodium sulfate generated from a boiling water type nuclear reactor, waste solution is fed into a thin film evaporator where the waste solution is evaporated and made into powder while precipitating in a peripheral surface of the evaporator vessel. The surface of the precipitated solid is wiped by rotating wiper blades and removed off as radioactive solid powder. The rotational speed of a rotor to which the wiper blades are secured is controlled at a minimum and necessary rotational speed which contributes to make the waste solution into the powder so that the rate of worn out of the wiper blade is decreased.
Pionier-I is a vertical axis wind turbine (VAWT) of the Darrieus-type with a diameter of 15 m. In the month of September 1983 performance and efficiency were measured. Measurements were done with constant rotational speed and with constant tip speed ratio. For the calculation of the possible (theoretical) output of electric power an anemometer was present. Measurement results are conditioned to one digital signal and processed by a microcomputer (Apple II). It becomes evident that the yearly energy output of the Pionier-I is quite well comparable with that of a horizontal axis turbine with the same diameter.
After having studied the shape that a tachyon T (e.g., intrinsically spherical) would take up, we show in an explicit example that the characteristics of classical tachyons are similar to those of the ordinary (slower-than-light) quantum particles. In particular, a realistic tachyon is associated with a ''phase speed'' V(V/sup 2/>c/sup 2/), but with a ''group speed'' upsilon=c/sup 2//V (upsilon/sup 2/
Spectral room temperature photoluminescence (pl) of polycrystalline Cu(In,Ga)Se2 films (CIGSe) is evaluated with respect to optoelectronic properties and in particular for the determination of the splitting of quasi-Fermi levels (EFn - EFp). For lateral resolution of ? 1 ?m a confocal pl-setup is used. The depth profile of the excess carrier densities determining the rates of radiative transitions strongly govern the spectral pl-shape which has been numerically modeled with a matrix transfer formalism. In this optical approach we discriminate for wave propagation and attenuation in a multilayer system between a plane-wave ansatz and a 3D-spherical formalism, depending on excitation area large or small/similar compared to the thickness of the absorber. In both cases re-absorption of photons in energetic regimes with absorption approaches unity, from which the splitting of the quasi-Fermi levels is preferentially deduced, substantially influence ...
A procedure and software have been developed to transform the area distribution of the residual surface heights available from the measurement with the Micromap interferometric microscope into a two-dimensional (2D) power spectral density (PSD) distribution of the surface height. The procedure incorporates correction of one of the spectral distortions of the PSD measurement. The distortion appears as a shape difference between the tangential and sagittal PSD spectra deduced from the 2D PSD distribution for an isotropic surface. A detailed investigation of the origin of the anisotropy was performed, and a mathematical model was developed and used to correct the distortion. The correction employs a modulation transfer function (MTF) of the detector deduced analytically based on an experimentally confirmed assumption about the origin of the anisotropy due to the asymmetry of the read-out process of the instrument's CCD camera. The ...
We present a detailed spectral analysis of point-like X-ray sources in the XMM-COSMOS field. Our sample of 135 sources only includes those that have more than 100 net counts in the 0.3-10 keV energy band and have been identified through optical spectroscopy. The majority of the sources are well described by a simple power-law model with either no absorption (76%) or a significant intrinsic, absorbing column (20%).As expected, the distribution of intrinsic absorbing column densities is markedly different between AGN with or without broad optical emission lines. We find within our sample four Type-2 QSOs candidates (L_X > 10^44 erg/s, N_H > 10^22 cm^-2), with a spectral energy distribution well reproduced by a composite Seyfert-2 spectrum, that demonstrates the strength of the wide field XMM/COSMOS survey to detect these rare and underrepresented sources.
With recent and archival Rossi X-Ray Timing Explorer (RXTE) X-ray measurements of the heavily obscured X-ray pulsar EXO 1722-363 (IGR J17252-3616), we carried out a pulse timing analysis to determine the orbital solution for the first time. The binary system is characterized by a_x sin(i) = 101 +/- 3 lt-s and P_orb = 9.7403 +/- 0.0004 days (90% confidence), with the precision of the orbital period being obtained by connecting datasets separated by more than 7 years (272 orbital cycles). The orbit is consistent with circular, and e 61 degrees at the 99% confidence level, the radius of the primary is between 21 R_sun and 37 R_sun, and its mass is less than about 22 M_sun. The acceptable range of radius and mass shows that the primary is probably a supergiant of spectral type B0I-B5I. Photometric measurements of its likely counterpart are consistent with the spectral type and luminosity if the distance to the system is between 5.3 kpc and 8.7 ...
We investigate the features of the spontaneous emission spectra in a coherently driven cold five-level atomic system by means of a radio frequency (rf) or microwave field driving a hyperfine transition within the ground state. It is shown that a few interesting phenomena such as spectral-line narrowing, spectral-line enhancement, spectral-line suppression, and spontaneous emission quenching can be realized by modulating the frequency and intensity of the rf-driving field in our system. In the dressed-state picture of the coupling and rf-driving fields, we find that this coherently driven atomic system has three close-lying levels so that multiple spontaneously generated coherence (SGC) arises. Our considered atomic model can be found in real atoms, such as rubidium or sodium, so a corresponding experiment can be done to observe the expected phenomena related to SGC reported by Fountoulakis et al. [Phys. Rev. A 73, 033811 ...
The {sup 252}Cf-source-driven noise analysis method is a versatile measurements tool that has been applied to measurements for initial loading of reactors, quality assurance of reactor fuel elements, fuel processing facilities, fuel reprocessing facilities, fuel storage facilities, zero-power testing of reactors, verification of calculational methods, process monitoring, characterization of storage vaults, and nuclear weapons identification. This method`s broad range of application is due to the wide variety of time- and frequency domain signatures, each with unique properties, obtained from the measurement. The following parameters are obtained from this measurement: average detector count rates, detector multiplicities, detector autocorrelations, cross-correlation between detectors, detector autopower spectral densities, cross-power spectral densities between detectors, coherences, and ratios of spectral densities. All of ...
The paper presents the investigations of plasma streams generated by pulsed plasma gun 'Prosvet' operated with different gases: krypton (m=84) and helium (m=4). Contour parameters of working gas spectral lines (full intensities and half-widths) are used for determination of spatial distributions of the electron density and temperature. Temporal distributions of the spectral lines intensities (both neutrals and ions of working gas), impurity spectral lines and continuum intensities are analyzed. Plasma stream velocity was estimated by time-of-flight method between two monochromators (MUM) connected with photo-multiplier. longitudinal distributions of the plasma pressure for different time moments and varied distances from the accelerator output have been used for investigation of the plasma stream dynamics and study the plasma compression in the focus region for different operational regimes of plasma accelerator. ...
We search for an infrared signature of the transiting extrasolar planet HD 209458b during secondary eclipse. Our method, which we call `occultation spectroscopy,' searches for the disappearance and reappearance of weak spectral features due to the exoplanet as it passes behind the star and later reappears. We argue that at the longest infrared wavelengths, this technique becomes preferable to conventional `transit spectroscopy'. We observed the system in the wing of the strong nu-3 band of methane near 3.6 microns during two secondary eclipses, using the VLT/ISAAC spectrometer at a spectral resolution of 3300. Our analysis, which utilizes a model template spectrum, achieves sufficient precision to expect detection of the spectral structure predicted by an irradiated, low-opacity (cloudless), low-albedo, thermochemical equilibrium model for the exoplanet atmosphere. However, our observations show no evidence for the presence ...
The aim of the present study focuses on experimentally demonstrating the efficacy of using angularly-variable fiber geometry to achieve the desired tissue-layer selection and probing depths with the further objective of enhancing the sensitivity and specificity of spectral diagnosis in stratified architectures that resemble human cervical epithelia. The morphological and biochemical features of epithelial tissue vary in accordance with tissue depths; consequently, the accuracy of spectroscopic diagnosis of epithelial dysplasia may be enhanced by probing the optical properties of this tissue. When correlated to cellular dysplasia, layer-specific changes in tissue optical properties may be deciphered by reflectance spectroscopy coupled with angularly-variable fiber geometry. This study addresses the utility of using such angularly-variable fiber geometry for resolving spatially-specific spectral signatures of tissue pathology. This is ...
Laboratory characterization of Interplanetary Dust Particles (IDPs) collected in the lower stratosphere represents a concrete analysis of cosmic dust properties which played a fundamental role in the origin and evolution of Solar System. The IDPs were characterized by Field Emission Scanning Electron Microscope (FESEM) analyses and by InfraRed (IR) micro-spectroscopy. We present the FESEM images of six IDPs: three smooth grains, two porous and one a compact sphere. We also show the results of micro-IR transmission measurements on four IDPs that allowed us to identify their spectral class according to the criteria defined by Sandford and Walker. Only three of the analyzed particles show IR transmission spectra with a dominant "silicate absorption feature" so that they could be assigned to the three IR spectral classes: one has been classified as "amorphous olivine", one appears to be a mixture of "olivines" and "pyroxenes" and one belongs to the ...
We consider a class of nonlinear Schrodinger / Gross-Pitaevskii (NLS/GP) equations with periodic potentials, having an even symmetry. We construct "solitons", centered about any point of symmetry of the potential. For focusing (attractive) nonlinearities, these solutions bifurcate from the zero state at the lowest band edge frequency, into the semi-infinite spectral gap. Our results extend to bifurcations into finite spectral gaps, for focusing or defocusing (repulsive) nonlinearities under more restrictive hypotheses. Soliton nonlinear bound states with frequencies near a band edge are well-approximated by a slowly decaying solution of a homogenized NLS/GP equation, with constant homogenized effective mass tensor and effective nonlinear coupling coefficient, modulated by a Bloch state. For the critical NLS equation with a periodic potential, e.g. the cubic two dimensional NLS/GP with a periodic potential, our results imply that the limiting ...
Accretion processes in quasars and active galactic nuclei are still poorly understood, especially as far as the connection between observed spectral properties and physical parameters is concerned. Quasars show an additional degree of complexity compared to stars that is related to anisotropic emission/obscuration influencing the observed properties in most spectral ranges. This complicating factor has hampered efforts to define the equivalent of an Hertzsprung-Russel diagram for quasars. Even if it has recently become possible to estimate black hole mass and Eddington ratio for sources using optical and UV broad emission lines, the results are still plagued by large uncertainties. Nevertheless, robust trends are emerging from multivariate analysis of large spectral datasets of quasars. A firm observational basis is being laid out by accurate measurements of broad emission line properties especially when the source ...
The /sup 252/Cf-source-driven neutron noise analysis method for obtaining the subcriticality of an assembly of fissile material from cross-power spectral densities (CPSDs) was developed to avoid some difficulties inherent in other measurement methods. This method requires measurement of frequency-dependent CPSD between a pair of detectors in or near the fissile assembly and CPSDs between these detectors and a source of correlated neutron noise from an ionization chamber containing /sup 252/Cf, also in or near the fissile assembly. Also, the auto-power spectral density of the source is required. The ratio of spectral densities is then formed and is related to the subcriticality. To date various measurements have been performed which demonstrate the usefulness of the method including measurements with single uranium metal cylinders. The experiments described here, which used coupled uranium (93.15 wt % /sup 235/U) metal ...
This dissertation deals with both the theoretical and the technological aspects of monolithic tunable lasers, and the experimental techniques for opto-electronic integration. In the theoretical part, the principles and limitations of wavelength tuning and spectral linewidth reduction in monolithic semiconductor lasers are described, with coupled distributed feedback-Fabry Perot (DFB-FP) lasers and long DFB lasers as examples. Stepwise tuning of wavelength over tens of nanometers and continuous tuning over the range of a mode spacing are shown to be possible. Spatial hole burning is found to affect the spectral linewidth of lasers involving strong active gratings. On the technological side, one of the major issues is the fabrication of flexible gratings. Direct-writing techniques, such as focused ion beam (FIB) implantation and e-beam lithography, provide the resolution, flexibility and accuracy that conventional holographic lithography lacks. ...
The spectrum, angular distribution, polarization and coherence properties of the radiation emitted by relativistic electrons undulating through a quasiperiodic tapered magnetic field are studied. Tapering the wavelength and/or field strength along the undulator's axis has the effect of spreading the spectral line to higher frequencies; interference over this broader spectral range results in a more complex line shape. The angular dependence, on the other hand, is not affected by the amount of taper. The polarization of the radiation in the forward direction is determined by the transverse polarization of the undulator, but the polarization changes off axis. The radiation patterns predicted here are distinct from those of untapered undulators, and their detection is now feasible. They will provide useful diagnostics of electron trajectories and threshold behavior in free-electron-laser oscillators using tapered undulators.
The theory of a method of determination of the reactivity from power spectral density measurements with /sup 252/Cf and the results of experiments with a critical assembly mock-up of a liquid-metal fast breeder reactor and with uranium (93.2 wt % /sup 235/U) metal cylinders and a sphere are presented. This method of reactivity determination has an advantage over existing methods in that it determines the reactivity only from properties of the reactor at the subcritical state of interest and thus does not require a calibration near delayed criticality. In these experiments the reactivity was varied by changing the fissile loading or the amount of neutron absorber inserted; for the LMFBR mock-up, the reactivity varied to approximately 75 dollars subcritical, and for the uranium metal assemblies, to approximately 30 dollars subcritical.
The experimental technique used for detection of subcooled boiling through analysis of the fluctuation contained in pressure transducer signals is presented. This work was partly conducted at the Institut fuer Kerntechnik und zertoerungsfreie Pruefverfahren von Hannover (IKPH, Germany) in a thermal-hydraulic circuit with one electrically heated rod with annular geometry test section. Piezo resistive pressure sensors are used for onset of nucleate boiling (ONB) and onset of fully developed boiling (OFDB) detection using spectral analysis/ signal correlation techniques. Experimental results are interpreted by phenomenological analysis of these two points and compared with existing correlation. The results allow to conclude that this technique is adequate for the detection and monitoring of the ONB and OFDB. (author)
The experimental technique used for detection of subcooled boiling through analysis of the fluctuation contained in pressure transducer signals is presented. This work was partly conducted at the Institut fuer Kerntechnik und zertoerungsfreie Pruefverfahren von Hannover (IKPH, Germany) in a thermal-hydraulic circuit with one electrically heated rod with annular geometry test section. Piezo resistive pressure sensors are used for onset of nucleate boiling (ONB) and onset of fully developed boiling (OFDB) detection using spectral analysis/ signal correlation techniques. Experimental results are interpreted by phenomenological analysis of these two points and compared with existing correlation. The results allow to conclude that this technique is adequate for the detection and monitoring of the ONB and OFDB. (author)
Monte Carlo neutron transport methods can be used to verify the applicability of point kinetics for safety analysis of nuclear reactors. KENO-NR was used to obtain the transfer function of the Advanced Neutron Source reactor and the time delay between the core power production and the external detectors, a parameter of interest to the safety systems design. The good agreement between the Monte Carlo generated transfer function and the point kinetics transfer function validates that the uncommon ANS geometry does not preclude the use of point kinetics in the frequency range that was investigated. Various features of the power spectral densities also demonstrated the applicability of point kinetics. The time delay was obtained from the cross-power spectral density (CPSD) and is {approximately}15 ms. These analyses show that frequency analysis can be used experimentally to investigate the validity of the use of point kinetics models in critical ...
The high-frequency data from 12 sensors at the ITCE 1976 are analyzed to determine the Kolmogoroff constants for velocity, temperature and humidity fluctuations, ..cap alpha../sub u/, ..cap alpha../sub T/, and ..cap alpha../sub q/. The occurrence of aliasing in the spectral analysis in some cases together with the limited response of some sensors at the higher frequencies introduces some uncertainties into the analysis. The Soviet sonic anemometer, fine-wire thermometer and infrared hygrometer and the Australian infrared hygrometer provide the best information, namely that: ..cap alpha../sub u/ = 0.59 +/- 0.01, ..cap alpha../sub T/ = 0.68 +/- 0.02, ..cap alpha../sub q/ = 0.76 +/- 0.03, where the errors quoted refer solely to statistical errors. The other instruments provide general support to these values. The technique of using spectral density measurements to determine eddy fluxes is illustrated.
The launch of the first spaceborne hyperspectral instrument, Hyperion, in 2000 has provoked further research into its capabilities with regard to mineral exploration. Our study in the remote, mountainous region of Pulang, China employed a two-step progressive approach, first to locate target areas characterized by hydrothermal mineral alteration, using the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), and secondly, to attempt detailed mineral mapping using Hyperion. The preliminary target detection involved principal components and broad-band spectral analysis and led to the detection of two target areas characterized by argillic alteration, iron-oxide- and sulphate-bearing minerals. A focused hyperspectral study followed using Spectral Angle Mapper (SAM) and Mixt...
We propose and analyze a novel regenerative amplifier free electron laser (FEL) to produce fully coherent x-ray pulses. The method makes use of narrow-bandwidth Bragg crystals to form an x-ray feedback loop around a relatively short undulator. Self-amplified spontaneous emission (SASE) from the leading electron bunch in a bunch train is spectrally filtered by the Bragg reflectors and is brought back to the beginning of the undulator to interact repeatedly with subsequent bunches in the bunch train. The FEL interaction with these short bunches not only amplifies the radiation intensity but also broadens its spectrum, allowing for effective transmission of the x-rays outside the crystal bandwidth. The spectral brightness of these x-ray pulses is about two to three orders of magnitude higher than that from a single-pass SASE FEL.
Electrostatic fields of the order of 1 V/Angst, as they occur at field emission tips, are comparable to those experienced by valence electrons in atoms and molecules. Such fields are strong enough to induce a significant redistribution of the valence charge in chemical bonds. In this work we investigate the effects on the electronic properties of a single adatom on a metal surface induced by the presence of an electrostatic field. In particular we present the results of a full ab initio DFT calculation, within the embedding method, of the CCV Auger spectra of Si and Mg atoms in and on a jellium-Ag host. Differently from impurities in bulk, Auger spectral profiles of adsorbates on metal surfaces can show notable modifications due to the applied electric field.
The electron-phonon spectral distribution function #alpha#"2(#omega#) F (#omega#) has been calculated for niobium. The electron energy bands and wave functions were obtained from a self-consistent augmented-plane-wave muffin-tin potential, and the electron-phonon matrix elements were evaluated using the so-called rigid-ion approximation. With this approximation it is found that #alpha#"2(#omega#) is constant over the whole energy spectrum. The electron-phonon mass enhancement has also been calculated for local regions of the Fermi surface and found to be anisotropic. The calculated local values of the enhancement do not agree with experimental values available for different orbits from de Haas--van Alphen measurements. The discrepancy seems to arise because the bare-rigid-ion matrix elements are relatively small between states with nearly pure l = 2 character.
Knowledge on environmental variability and how it is affected by disturbances is crucial for understanding patterns of biodiversity and determining adequate conservation strategies. The aim of this study is to assess environmental variability in patches undergoing post-fire vegetation recovery, identifying trends of change and their relevant drivers. We particularly evaluate: the value of three spectral indices derived from Landsat satellite data [Normalized Burn Ratio (NBR), Normalized Difference Vegetation Index (NDVI) and Wetness Component of the Tasseled Cap Transformation (TCW)] for describing secondary succession; the effectiveness of three metrics (diversity, evenness and richness) as indicators of patch variability; and how thematic resolution can affect the perception of environme...
Waste electrical and Electronic Equipment (WEEE) constitutes 4% of the municipal waste in Europe, being increased by 16-28% every five years. Nowadays, Europe produces 6,5 million tonnes of WEEE per year and currently 90% goes to landfill. WEEE waste is growing 3 times faster than municipal waste and this figure is expected to be increased up to 12 million tones by 2015. Applying a new technology to separate non-ferrous metal Waste from WEEE is the aim of this paper, by identifying multi-and hyper-spectral materials and inserting them in a recycling plant. This technology will overcome the shortcomings passed by current methods, which are unable to separate valuable materials very similar in colour, size or shape. For this reason, it is necessary to develop new algorithms able to distinguish among these materials and to face the timing requirements. (Author). 22 refs.
The Formula Not Shown system of Formula Not Shown was first observed in auroral emissions by Meinel in 1950. Although the Formula Not Shown band system has been reinvestigated since this first spectral study, no laboratory spectrum of the (2,1) vibronic band has been obtained. We have recently built a continuous-wave cavity ringdown spectrometer, and as a first test of this spectrometer we observed the (2,1) band of Formula Not Shown in a positive column discharge cell. Many lines of the first positive band system of Formula Not Shown were also identified during the process of assigning this spectrum. The relative intensities of the Formula Not Shown and Formula Not Shown bands were found to change with discharge cell pressure, and so each spectral region was observed at two pressures to a...
This paper will provide an overview of the Common Aperture Multispectral Sensor (CAMS) Hardware Demonstrator. CAMS is a linescanning sensor that simultaneously collected digital imagery over the Far-IR (8 to 12 {mu}m) and visible spectral (0.55 to 1.1 PM) spectral bands, correlated at the pixel level. CAMS was initially sponsored by the U.S. Naval Air System Commands F/A-18 program office (PMA-265). The current CAMS field tests are under the direction of Northrop-Grumman for the Defense Nuclear Agency (DNA) in support of the Follow-On Open Skies Sensor Evaluation Program (FOSEP) and are scheduled to be conducted in April 1996. 8 figs., 4 tabs.
The Full Aperture Backscatter System (FABS) provides a measure of the spectral power, and integrated energy scattered by stimulated Brillouin (348-354 nm) and Raman (400 - 700 nm) scattering into the final focusing lens of the first four beams of the NIF laser. The system was designed to provide measurements at the highest expected fluences with: (1) spectral and temporal resolution, (2) beam aperture averaging, and (3) near-field imaging. This is accomplished with a strongly attenuating diffusive fiber coupler and streaked spectrometer and separate calibrated time integrated spectrometers, and imaging cameras. Measurement of the wavelength dependent sensitivity of the complete system is accomplished with a calibrated Xe lamp. Data from the calibration system is combined with experimental data to produce the power and energy measurements. Examples of measurements will be discussed.
A plutonium gamma-ray analysis system that operates on MS-DOS-based computers has been developed for the International Atomic Energy Agency (IAEA) to perform in-field analysis of plutonium gamma-ray spectra for plutonium isotopics. The program titled IAEAPU consists of three separate applications: a data-transfer application for transferring spectral data from a CICERO multichannel analyzer to a binary data file, a data-analysis application to analyze plutonium gamma-ray spectra, for plutonium isotopic ratios and weight percents of total plutonium, and a data-quality assurance application to check spectral data for proper data-acquisition setup and performance. Volume 3 contains the software listings for these applications.
From aerosol spectral optical depths ({tau}{sub p{lambda}}) at wavelengths in the range 380 to 1025 nm estimated at different locations in the near and far coastal regions of the Arabian sea adjoining the western coast of central India, the spatial and spectral characteristics of coastal aerosols and the effect of the proximity to the (urban) continent are investigated. The Aangstroem parameters are deduced from {tau}{sub p{lambda}} values. A significant increase, both in aerosol optical depths at shorter (visible) wavelengths ({lambda} {<=} 600 nm) and the Aangstroem wavelength exponent are observed in the near coastal regions, suggesting an increase in the (relative) concentration of sub micron particles, apparently of anthropogenic origin. The Aangstroem turbidity coefficient remains nearly steady spatially, indicating a (spatially) uniform loading of large particles. 31 refs, 10 figs, 1 tab
A prism spectrometer has been developed to operate in the VUV wavelength range from 120 to 200 nm. It can be used as a pre- disperser in conjunction with a Fabry-Perot based gas refractometer. This instrument has also been used to measure the refractive index of the liquid radiator C/sub 6/F/sub 14/ in various spectral lines. This radiator is used in the RICH detectors of the DELPHI experiment and has been proposed for ALICE, and LHCb experiments. The spectral resolution of the system is improved as the wavelength decreases and the data are consistent with a wavelength accuracy about 0.4 nm at 140 nm. The results for the dispersion curve of the above liquid are presented. (17 refs).
Canadian railway traffic is delayed until lines are plowed of snow following heavy snowfalls. A modification that would permit higher plowing speeds and fewer delays could realize significant benefits in addition to direct fuel and labor savings. The objective of this project was to carry out a cost benefit analysis on a low-friction coating applied to a mainline railway snow plow. The assessment was carried out using old Canadian National Railway snow plows for test purposes. An analytical model was developed to estimate the importance of friction reduction to fuel consumption and power requirements. The sensitivity analysis revealed a bump or discontinuity in the power vs speed profile, corresponding to the minimum plow speed at which the snow will cease to flow over the plow. Reducing the coefficient of friction reduces this minimum plowing speed. This could mean the difference between success and ...
A gas-diesel dual fuel engine apparatus is described having a diesel engine, a diesel fuel supply system including a diesel fuel injection pump, a gaseous fuel supply system including a gaseous fuel regulating valve, and a governing and controlling device for governing the speed of the engine through the control of fuel supplied to the engine and controlling the switchover of the operation of the engine between a diesel fuel mode and a gaseous fuel mode. The improvement of the governing and controlling device consists of: (a) at least one electronic governor means adapted to compare a speed signal representing the actual operating speed of the diesel engine with a set speed signal representing the set speed thereof; (b) a pair of electric actuator means having respective power amplifier circuits and mechanically connected to the diesel fuel injection pump and the gaseous fuel ...
The effect of electron beam welding parameters on fusion zone (FZ) microstructure and porosity in a Ti-6.8 Al-3.42 Mo-1.9 Zr-0.21 Si alloy (Russian designation VT 9) has been investigated. It has been observed that the FZ grain width increased continuously with increase in heat input when the base metal was in the #beta# heat-treated condition, while in the #alpha# + #beta# heat-treated base metal welds, the FZ grain width increased only after a threshold energy input. The difference is attributed to both the weld thermal cycle and the pinning effect of equiaxed primary alpha on grain growth in the heat-affected zone (HAZ) of #alpha# + #beta# heat-treated base metal. Postweld heat treatment (PWHT) in the subtransus and supertransus regions did not alter the columnar grain morphology in the FZ, possibly due to the lack of enough driving force for the formation of new grains by the breaking up of the columnar grains and grain boundary movement for grain growth. The highest porosity was ...
It is carried out a calculation to determine the energy spectra of secondary {sup 3}He at small atmospheric depths. It is produced in the spallation reaction of primary helium and heavier nuclei in the overlying atmosphere. It is examined the effect of the geomagnetic cut-off on the spectral shape of the secondary {sup 3}He nuclei. The calculations are being carried out for both solar minimum and maximum periods. Results from these calculations will be presented at the Conference.
Power spectral analysis of cosmic ray intensity recorded by neutron monitors at Calgary and Deep River, Alberta, was carried out over a wide range of frequencies from 3 {times} 10{sup {minus}9} Hz to 6 {times} 10{sup {minus}6} Hz during the epoch 1965-1989 and revealed different behavior of the power spectral density for the three ranges of frequency domains. At low frequencies corresponding to the periodicity T {approx} 20 months the power spectrum shows an abrupt change in the level and profile of power spectral density (PSD). This indicates that the processes responsible for the long period variations are different from the one which causes short-period variations. At middle frequencies corresponding to periodicities between 6 and 18 months, the PSD indicates that the periodicities are not stable and show a transient character over the entire epochy of analysis. The PSD for periods T {approx} 27 days indicates an 11 year ...
The synthesis of novel b-functionalized derivatives of the clinically used photosensitizer Temoporfin has been achieved by nucleophilic addition reactions to a corresponding diketo chlorin. The b-substituted dihydroxychlorin products exhibit a strong absorption in the red spectral region, a high singlet oxygen quantum yield, and were found to be highly effective in in vitro assays against HT-29 tumor cells.
The defect-induced effect on superconducting transition temperature T_c of A-15 compounds is examined. T_c is found from the Eliashberg equations which take into account the defect-induced changes in the electron-phonon spectral function and electron density of states. The dependence of T_c on the defect type in the superconductor is obtained.
Phenomenological accountancy of quanta-electrodynamic corrections by means of introduction into multielectron theory of short-term potential, the parameters whereof are calibrated in such a way that provides for correct reproduction of the Lamb shift of the 1s-orbital energy for a correspondingly selected effective charge is developed by example of d-line of Na-like multicharged ions.
Sorption of oxidized and reduced forms of molybdosilicic, molybdophosphoric and molybdovanadophosphoric acids by polyurethane foam based on ethers and esters is studied. On the basis of sorption dependence on solution pH, polyurethane foam type and spectral characteristics of sorbates the suggestion has been made that in the polyurethane foam phase there are two main types of sorbent-sorbate interaction: electrostatic (ion-ion) and with hydrogen bond formation: and it is impossible to determine the contribution of every interaction
We study quasifinite highest weight modules over the supersymmetric extension of the W_1_+_#infinity# algebra on the basis of the analysis by Kac and Radul. We find that the quasifiniteness of the modules is again characterized by polynomials, and obtain the differential equations for highest weights. The spectral flow, free field realization over the (B, C)-system, and the embedding into gl(#infinity#vertical stroke #infinity#) are also presented. (orig.).
The method of spectral disentangling has now created the opportunity for studying the chemical composition in previously inaccessible components of binary and multiple stars. This in turn makes it possible to trace their chemical evolution, a vital aspect in understanding the evolution of stellar systems. We review different ways to reconstruct individual spectra from eclipsing and non-eclipsing systems, and then concentrate on some recent applications to detached binaries with high-mass and intermediate-mass stars, and Algol-type mass-transfer systems.
Gas chromatography-selected ion monitoring-mass spectral analysis using [13C6]indole-3-acetic acid (IAA) as an internal standard provides an effective means for quantitation of...Full Text Available
In this work we study the temperature dependence of the Soret band lineshape of the carbonmonoxy derivatives of sperm whale myoglobin, human hemoglobin, and its isolated alpha and beta subunits. To...Full Text Available
A general theorem on the GBDT version of the B\\"acklund-Darboux transformation for systems rationally depending on the spectral parameter is treated and its applications to nonlinear equations are given. Explicit solutions of direct and inverse problems for Dirac-type systems, including systems with singularities, and for the system auxiliary to the $N$-wave equation are reviewed. New results on explicit construction of the wave functions for radial Dirac equation are obtained.
Using spectral hole-burning-based ultraslow group velocity in a dilute solid medium, we report enhanced photon echo efficiency three orders of magnitude higher than that in a nonslow light regime. The enhancement is due to exponentially increased absorption of an optical data pulse owing to the enhanced photon-atom interaction in an ultraslow light regime, whereas echo reabsorption is negligibly small due to group-velocity dependent population depletion.
Calculating the local spectral densities at magnetic adatoms, we estimate the variation in the Yosida-Kondo resonance due to the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction and the direct exchange between adatoms in systems of magnetic trimers on metal surfaces. The results show that the RKKY interaction leads to the gradual variation in Kondo temperature, and the direct exchange can be the origin of the drastic variation. (author)
The gauge-invariant correlation function for the Yang-Mills field strengths is shown to admit a symmetric decomposition into electric and magnetic components. The spectral weights are seen to obey a sum rule of the superconvergence type, owing to asymptotic freedom. The close relation between the dielectric function, electric-magnetic duality, and the algebra of generalized Chern-Simons charges is illustrated for the linearized Yang-Mills-Higgs system.
We report the corrected intercomparison of the World Radiometer Reference (WRR) irradiance scale and the Electrotechnical Laboratory (ETL) spectral irradiance scale. In addition, we confirm the intercomparison precision using the test facility where the irradiance of ETL 500 W standard lamp can be measured directly with the cavity radiometer. The results showed that the irradiance based on the WRR scale was 0.5-0.7% lower than the one based on the ETL scale
We construct the Generalized Monodromy matrix $\\mathcal{\\hat{M}}(\\omega)$ of two dimensional string effective action by introducing the T-duality group properties.The integrability conditions with general solutions depending on spectral parameter are given. This construction is investigated for the exactly solvable Wess, Zumino, Novikov and Witten (WZNW) model in pp-wave Limit when B=0.
In scattering of channeled particles by point defects and in emission of gamma rays in the spontaneous-radiation spectral region conditions are attained where the momentum transferred to the defect is taken up by the crystal as a whole. This leads to coherent and interference effects in the radiation from the crystal defects. When the longitudinal momentum transferred is zero, an induced radiation effect appears in the transitions between the states of transverse motion.
The indirect detection of particle dark matter (DM) is based on the search for anomalous components in cosmic rays (CRs) due to the annihilation of DM pairs in the galactic halo, on the top of the standard astrophysical production. These additional exotic components are potentially detectable at Earth as spectral distortions for the various cosmic radiations: $\\chi + \\chi \\to q \\bar{q}, W^+ W^-, ... \\to \\bar{p}, \\bar{D}, e^+ \\gamma and \
The gamma-ray spectrum following neutron capture on /sup 87/Sr was measured at 3 neutron energies: E/sub n/ = thermal, 2 keV, and 24 keV. Gamma rays were detected in a three-crystal Ge(Li)-NaI-NaI pair spectrometer. Gamma-ray intensities deduced from these spectra by spectral unfolding are presented.
Previous experiments in fast critical assemblies demonstrated a method of determining reactivity from power spectral density measurements with /sup 252/Cf. This method determines reactivity from properties of the reactor only at the subcritical state of interest, thus it does not require a calibration near delayed criticality. The interpretation of the measured data to obtain reactivity does not require knowledge of the relative or absolute values of the source intensity, knowledge of the detection efficiencies, or knowledge of the detection instrumentation frequency responses. An experiment was performed at the Pool Critical Assembly to evaluate the possibility of /sup 252/Cf source driven neutron noise spectral density measurements in light water moderated reactors. This experiment showed that using commercially available detectors, such measurements can be performed in a reasonable time, that is, the measurement of the quantity of interest ...
From nuclear science symposium; San Francisco, California, USA (14 Nov 1973). A digital Fourier analyzer was programmed to perform reactor neutron noise analysis measurements and on-line processing of the data to obtain the steady-state reactivity. The system is suitable for recovering cross spectral density with low correlatedsignal component and for repetitive measurements with efficient use of reactor time. (auth)
This document describes measurements of the directional spectral emittance of four ceramic mold materials. The work was performed with the samples at {approximately} 900{degree}C in a vacuum vessel pumped to {approximately}3 {times} 10{sup {minus}6}Torr. Results conform to expectations derived from prior work done with similar samples.
The application of differential optical absorption (DOA) techniques for the in-situ determination of the chemical composition of coal gasification process streams is investigated. Absorption spectra of relevant molecular species and the temperature and pressure effects on DOA-determined spectral characteristics of these species will be determined and cataloged. A system will be configured, assembled, and tested.
This paper investigates the spectral characteristics of three-dimensionally porous carbon dioxide indicators based on a porous silicate glass and phenolphthalein. The absorption spectra of the original solutions of phenolphthalein in alkaline and acid solutions are shown. The solutions were acidified by bubbling CO/sub 2/ through an alkaline phenolphthalein solution. The authors have succeeded in producing a reversible colorimetric adsorption indicator for carbon dioxide which after proper calibration enables the CO/sub 2/ content of an atmosphere to be estimated quantitatively.
Besarhanamides A (1) and B (2) are fatty acid amides purified from the marine cyanobacterium, Lyngbya majuscula, collected from Pulau Hantu, Singapore. The structure determination of these secondary metabolites was carried out using extensive 2D NMR spectral data as well as chemical manipulations including the Marfey's method. In addition, besarhanamide A exhibited moderate toxicity with LD50 at 13mM in the brine shrimp toxicity bioassay.
The theory of neutron moderation and spectroscopy are briefly reviewed, and moderators that are useful for Bonner sphere spectrometers are discussed. The choice of the neutron detector for a Bonner sphere spectrometer is examined. Spectral deconvolution methods are briefly reviewed, including derivative, parametric, quadrature, and Monte Carlo methods. Calibration is then discussed. (LEW)
We consider the pre-Big-Bang scenario with a massive axion field which starts to dominate energy density when oscillating in an instanton-induced potential and subsequently reheats the universe as it decays into photons, thus creating adiabatic CMB perturbations. We find that the fluctuations in the axion field can give rise to a nearly flat spectrum of adiabatic perturbations with a spectral tilt {delta}n in the range -0.1< or approx. {delta}n < or approx. 1.
In the paper is studied the physics of a free electron laser (FEL) based on a two-frequency undulator (TFU) which induces large non linear effects, especially on the spectral dynamics. These effects are analyzed in an extended formalism where the spontaneous emission, the low-gain regime and the strong-field saturation regime are studied. Numerical simulations show that the optimized TFU generates a laser field having both a large extraction efficiency and a narrow spectrum.
By treatment of ?-substituted acetylacetone derivatives with boron trifluoride etherate a series of earlier unknown boron difluoride complexes is obtained. The series includes binuclear complexes containing boron in the chelate fragment connected via sulfur or selenium atom. Gas chromatographic and spectral characteristics of the obtained compounds were investigated. By means of chromato-mass spectrometry their reaction with hydrazine in acidic and alkaline media was studied
Based on our cryogenic FT-IR spectroscopic studies of hydrogen bonds in cholic acid, the two-dimensional FT-IR spectroscopy was applied to enhance our understanding of the hydrogen bonds. Fine spectral structures were revealed by asynchronous 2D FT-IR spectra. The co-relationship among various bands was discussed according to the synchronous 2D FT-IR spectra. .
This is a report of the above-named solar car race from Darwin to Adelaide, Australia. On January 7, 1983, an Australian adventurer Mr. Hans Tholstrup succeeded in running from the Australian west coast to Sydney in a car driven solely by solar energy. The travel took 20 days, at an average speed of 23km per hour. The technology has made remarkable advances since his success and, in the World Solar Challenge 1993 held in November 1993, a Honda team crossed the Australian Continent at an average speed of 85km per hour. Technical challenges included the development of maximum-output solar cell panels, a car designed to make full use of such power, and a run at the maximum possible speed, all these dependent solely on the sun as energy source. This report Part I contains the details of the race, analysis, aerodynamics, car body structure, manufacture, materials, and so forth. (NEDO)
The aerodynamic behavior of a vertical axis wind turbine (VAWT) is analyzed by means of 2D particle image velocimetry (PIV), focusing on the development of dynamic stall at different tip speed ratios. The VAWT has an unsteady aerodynamic behavior due to the variation with the azimuth angle {theta} of the blade's sections' angle of attack, perceived velocity and Reynolds number. The phenomenon of dynamic stall is then an inherent effect of the operation of a VAWT at low tip speed ratios, impacting both loads and power. The present work is driven by the need to understand this phenomenon, by visualizing and quantifying it, and to create a database for model validation. The experimental method uses PIV to visualize the development of the flow over the suction side of the airfoil for two different reference Reynolds numbers and three tip speed ratios in the operational regime of a small urban wind turbine. The ...
This study presents three-dimensional simulation results of multispecies and multi-reaction electrorefining for spent nuclear waste treatment. Fluid-dynamic behavior of electrorefining is analyzed by commercial computational fluid-dynamics code. The results of local fluid dynamics are coupled with one-dimensional electrochemical reaction analysis code in order to predict local current density distribution. The new approach shows current distribution patterns over the cathode surface in LiCl-KCl molten-salt electrolyte. The current density distribution patterns are analyzed for various electrode rotational speeds and diverse applied currents and the results show a good agreement with general principle of mass transfer observations. Spatially periodic and vertically striped pattern of current density is predicted at the cathode side due to mass transfer depression at separation points. These slow mass transfer regions are vulnerable to be contaminated by transuranic ...
The influence of chemical composition and heat treatment on a low-carbon steel, chromium steel and high speed steel has been examined by polarisation curves and electrochemical parameters deduced from the Tafel plots. The electrochemical corrosion resistance, which is small between the as-received steels become greater after heat treatment, following the order: carbon steel < chromium steel #approx# high speed steel. To explain these differences, the nano- and microstructure of the steels has been characterized by the ex situ techniques of atomic force microscopy and optical microscopy, before and after surface etching with Nital (a solution of 5% HNO_3 in ethanol). This causes preferential attack of the ferrite phases showing the carbide phases more clearly. From these nanostructural studies it was possible to better understand why the passive films formed on chromium steel and high speed steel have superior protective ...
% In this work we investigated, in the Smooth Particle Hydrodynamics (SPH) framework, the development of spiral structures and shock fronts in the radial flow of accretion discs in close binary systems. These shock waves take place when the initially supersonic radial flow penetrating the disc bulk, reduces substantially its speed becoming suddenly subsonic. To this purpose, keeping constant the mass of the compact primary (M1 = 1 MO ), the separation between the two components and the injection speed at the inner Lagrangian point L1 (close to the local sound speed), we carried out 2D SPH simulations for four values of the stellar mass ratio M2/M1. We worked out 2D models because the damping effect of the artificial viscosity is too strong in 3D. Furthermore, the 2D environment seems the most suitable in order to evidence shock fronts in highly compressible gases. The results show that spiral structures and shock fronts ...
Within the context of practice-oriented constraints the speed and output power control of power plant turbines represents a big challenge for engineers for designing low order controllers with only a few parameter settings and in order to meet the requirements of the Deutsche Verbundgesellschaft. The results of a detailed study of the current standard and an improvement of the speed dynamic for load rejections are shown. (orig.) [German] Die Regelung der Drehzahl und die Leistung von Kraftwerksturbinen stellt im Rahmen von praxisorientierten Nebenbedingungen, wie z.B. dem Einsatz von Reglern geringer Ordnung mit wenigen Einstellparametern und den Vorgaben der Deutschen Verbundgesellschaft, eine grosse Herausforderung fuer den Entwicklungsingenieur dar. Die Ergebnisse einer ausfuehrlichen Untersuchung des bisherigen Standards und einer Verbesserung der Drehzahldynamik bei sogenannten Abfangpruefungen werden vorgestellt. (orig.)
A parametric experimental investigation of an 85 millimeter bore angular contact ball bearing running in RP-1 fuel was performed at speeds of 10,000 to 24,000 rpm. Thrust loads were varied from 4450 to 17,800 Newtons (1000 to 4000 lbs.). Radial loads were varied from 1335 to 13,350 Newtons (300 to 3000 lbs.). RP-1 lubrication for the bearing was provided through a stationary jet ring located adjacent to the test bearing outer ring. Increases in both the thrust and radial loads resulted in increased bearing temperature, while increases in shaft speed resulted in much more dramatic increases in bearing temperature. These trends are typical for ball bearings operating under these types of conditions. Results are given for outer ring temperatures of the test bearing at the various test conditions employed. In addition, the heat energy removed from the bearing by the RP-1 was determined by measuring the increase in temperature as the RP-1 passed ...
Non-evaporable thin film getters of various compositions have been produced by sputtering. Among about 20 materials which have been studied, the lowest activation temperature (about 180 degree C) has been displayed by a Ti-Zr-V coating obtained from a cathode made of intertwisted elemental wires. In order to optimize the vacuum properties of this film various production parameters, including the substrate temperature during coating, have been varied. The films have been characterized by pumping speed measurement, secondary electron microscopy, and X-ray diffraction. It has been found that the substrate coating temperature affects significantly the activation temperature, the pumping speed and the gas surface capacity. The highest pumping speed values, obtained for substrate coating temperatures of 250 degree C and 300 degree C, are clearly correlated with the increased surface roughness and porosity of the Ti-Zr-V film.
Large capacity adjustable speed machines (ASMs) at pumped storage power station have been put into full operation and the operating characteristics of ASM have been highly evaluated from the view point of power system operation. The output power (input power) of ASM can be controlled very quickly by applying a vector control scheme to the excitation control. This quick responsive feature of ASM can make it possible to improve the stability of the neighbor sub-power system. For improvement of transient stability, the output power of ASM is reduced very quickly in order to control the acceleration of neighbor generators during and after transmission line faults. For improvement of dynamic stability, the output power of ASM is modulated in accordance with the stabilizing signals detected from the swing of generator rotor or the power flow fluctuation on the transmission line. This paper describes the design concepts and method of control system for improving the ...
The environmental data for the NSDN are presented in the form of tables for each solar site. The solar sites are grouped into 12 zones, each of which consists of several adjacent states. The solar energy sites are in alphabetical sequence within each zone. The tables provide available meteorological data for reporting sites in the NSDN as follows: Insolation - the insolation table presents the total, diffuse, direct, maximum, and extra-terrestrial radiation for the solar site. It also shows the ratio of total extra-terrestrial radiation, as a percent. Temperature - the temperature table gives the average, daytime, nightime, maximum, minimum and inlet-water temperatures for the solar site. Additional tables are presented for some of these NSDN sites, supplying either wind or relative humidity data, or both. Wind - all of the passive and some of the active solar sites are equipped with wind sensors. These provide information for two wind tables. The first furnishes wind ...
The unit cost of energy production of wind generators is examined by means of a model of the turbine power curve and the Weibull model of wind probability function, by applying the usual economic equations. The analysis is carried out in terms of dimensionless variables whose range of variability is defined by examining the data of 80 modern commercial wind turbines; likewise, the economic parameters are based on the present state of costs. The unit cost decreases asymptotically when alpha (ratio between mean wind speed and cut-in speed) - increases and shows a lower limit of 2 to 5 Ecent/kWh. This cost depends both on the value of the machine parameter {phi} (ratio between nominal and cut-in speed) and on the basic prices. The effect of the Weibull shape parameter kappa is different according to the values of {alpha} and {phi}: with low {alpha} and high {phi} the unit cost increases along with {kappa} (that is with the ...
Optical measurement of the Doppler shift of laser backscatter, using a near-IR, visible, or ultraviolet laser, is potentially more robust and field reliable than coherent, heterodyne measurement with an IR laser. The direct measurement of the displacement of Fabry-Perot interference fringes is possible, but entails expensive, technically challenging, imaging detectors. The 'edge technique' permits Doppler shift measurements with relatively simple detectors and detector electronics, and has been implemented with Fabry-Perot etalons and with atomic line filters. Simple analytical models of the fringe imaging and edge detection techniques are presented, permitting ready calculation of the potential performance of either, for various atmospheric conditions and for various lidar hardware configurations. The predictions of the analytical models are confirmed by computer models, which in turn allow more detailed considerations of complicating factors such as solar backgrounds and the Rayleigh ...
Object: To smoothly control automatic water supply for realizing stable operation of a nuclear reactor by providing a flow rate limiting signal selection circuit and a preferential circuit in a water supply control device for a nuclear reactor wherein the speed of a recirculation pump may be changed in two-steps. Structure: Opening angle signals for a water supply regulating valve are controlled by a nuclear reactor water level signal, a vapor flow rate signal and a supplied water flow rate signal through an adder and an adjuster in response to a predetermined water level setting signal. When the water in the reactor is maintained at a predetermined level, a selection circuit receives a water pump condition signal for selecting one of the signals from a supplied water rate limiting signal generator generating signals for indicating whether one or two water supply pumps are operated. A low value preferential circuit passes the lower of the values generated from the ...
The instrument ball bearings are the key components of movable components for various kinds of measuring and control instruments; they often operate in the environmental condition of high-speed and light preload. In general, the non metal, disposable oilimpregnated retainer material has been used for these kinds of high precision miniature bearing. The engineering practice shows that the common failure mode of them is the wear which appears under the condition of insufficient lubrication condition. As the results, the vibration and noise will be enlarged, so does the frictional torque, which makes the ball bearings to lose its original working accuracy. It is the lifetime test of bearings that can enable the designers and manufacturers to chose the material of the bearing properly, optimize the product structure, mend the manufacturing technique process, and to enhance the technical level of the bearing products significantly. In this paper, the wear lifetime ...
It is proved that the mid-point grid, which is composed of samples obtained at ground track locations midway between crossover points (thus a subset of the full sampling), has the same resolving power as the full set; i.e., they resolve the same three-dimensional spectral space. The resolving power of the mid-point grid as derived previously by Tai (1995, 1998) is characterized by the Nyquist frequency ? c=? /T (where T is the repeat period of the exact-repeat satellite), and by (in local Cartesian coordinates) the zonal and meridional Nyquist wavenumber kc=2? /X and lc=2? /Y respectively (where X and Y are the east-west and north-south separation between adjacent parallel ground tracks). Here we re-derive this result in simplified terms. First, it is shown through the sampling theorem as demonstrated previously by Tai (1999) that even though samples of the real mid-point grid are not taken simultaneously, they resolve the same frequency range as that of a ...
The interaction of accretion disks with the magnetospheres of young stars can produce X-winds and funnel flows. With the assumption of axial symmetry and steady state flow, the problem can be formulated in terms of quantities that are conserved along streamlines, such as the Bernoulli integral (BI), plus a partial differential equation (PDE), called the Grad-Shafranov equation (GSE), that governs the distribution of streamlines in the meridional plane. The GSE plus BI yields a PDE of mixed type, elliptic before critical surfaces where the flow speed equals certain characteristic wave speeds are crossed and hyperbolic afterward. The computational difficulties are exacerbated by the locations of the critical surfaces not being known in advance. To overcome these obstacles, we consider a variational principle by which the GSE can be attacked by extremizing an action integral, with all other conserved quantities of the problem explicitly included ...
This paper presents a combined experimental and computational study into the aerodynamics and performance of a small scale vertical axis wind turbine (VAWT). Wind tunnel tests were carried out to ascertain overall performance of the turbine and two- and three-dimensional unsteady computational fluid dynamics (CFD) models were generated to help understand the aerodynamics of this performance. Wind tunnel performance results are presented for cases of different wind velocity, tip-speed ratio and solidity as well as rotor blade surface finish. It is shown experimentally that the surface roughness on the turbine rotor blades has a significant effect on performance. Below a critical wind speed (Reynolds number of 30,000) the performance of the turbine is degraded by a smooth rotor surface finis...
A simple tube-in-tube heat exchanger system for thermal energy storage employing stearic acid as PCM has been investigated. The performance and heat transfer characteristics of such a system were studied. Phase transition temperature range and times were measured and the speed of the phase transition front was computed. The melting front was found to move in the radial direction inward as well as in the axial direction from the top toward the bottom of the phase change material PCM tube. The speed of the melting front is enhanced by a convection heat transfer mechanism in the melted PCM. The heat transfer rate and, consequently, phase transition time can be altered by changing the water inlet temperature to the heat exchanger. In addition, a faster phase transition is realized by placing the heat exchanger in a horizontal position rather than a vertical one. (Author)
For the application of dynamic neutron radiography to the two-phase flow research using HANARO, several experimental items to which the radiography technique is beneficial were identified through the review of the outputs from the related researches and the discussions with experts. Also, the investigation of the equipments including the beam port, camera and converter was made and a hardware and a software for image processing were equipped. It was confirmed that the calibration curve for the attenuation of neutron beam in fluid which is required for the two-phase flow experiment could be obtained by the computer code calculation. Based on the investigation results on the equipment and the results from the measurement of BNCT beam characteristics, a high speed camera and an image intensifier will be purchased. Then, the high speed dynamic neutron radiography facility for two-phase flow experiments will be fully equipped.
The performance requirements of the Advanced Photon Source (APS) challenge the control system in a number of areas. This paper will review a few applications of advanced technology in the control and monitoring of the APS. The application of digital signal processors (DSPs) and techniques will be discussed, both from the perspective of a large distributed multiprocessor system and from that of embedded systems. In particular, two embedded applications will be highlighted, a beam position monitor processor and a DSP-based power supply controller. Fast data distribution is often a requirement. The application of a high-speed network based on reflective memory will also be discussed in the context of the APS global orbit feedback system. Timing systems provide opportunities to apply technologies such as high-speed logic and fiber optics. Examples of the use of these technologies will also be included. Finally, every modern accelerator control ...
A start safety apparatus of an engine adapted for a multipurpose power tool is described which consists of: an engine, an exciter coil generating alternate electromotive force in synchronism with rotation of the engine; an ignition coil having primary and secondary windings; a spark plug connected to the secondary winding of the ignition coil; a capacitor connected to the primary winding of the ignition coil the capacitor being charged with a positive half-cycle of the electromotive force; ignition timing control means for controlling discharge of the capacitor; a throttle control latch for setting a throttle valve of the engine in a predetermined throttle angle; a tool driven by the engine; and a centrifugal clutch transferring engine power to the tool when an engine speed exceeds a clutch-in speed.
After explaining the main causes for the limited power output of turbine generators with 50 s"-"1, the limits for superheated-steam turbines and for saturated-steam turbines are given. A comparison of the economy in the limiting output range (1,200 MW) shows that half load plants as well as two-shaft turbine generators do not bring any advantages as compared with a single-shaft turbine generator. For the selection of speed of the single-shaft turbine generator the planned way of application is decisive. For base load plants already a speed of 25 s"-"1 is economic in this power range. Concluding, some design features and problems of development for such large turbines with 25 s"-"1 for conventional steam conditions are discussed. (orig.).
Recognizing that a high percentage of transmission-line faults are single-phase to earth and temporary in nature, provides the impetus for considering single-pole switching as a means to enhance the reliability of EHV transmission systems. The effectiveness of single-pole switching schemes is largely determined by the speed with which the secondary arcs extinguish, and hence allow system restoration. Simulation techniques that enable better prediction of the faulted-system response are of obvious importance to the design and assessment of the various single-pole switching scheme applications. In this thesis, digital methods are developed to enable the faulted response of EHV systems to be simulated for a variety of different single-pole switching schemes. These include conventional single-pole switching, the hybrid method of autoreclosure, the neutral switched reactor, and the High Speed Grounding Switch implementations. The work is of ...
In the GE 7FDL single cylinder research diesel engine, in-cylinder high-speed photographic studies were conducted on coal-water slurry (CWS) fuel combustion. Distinct flames of pilot and CWS combustion were noticed. It was proven that the coal fuel burns after piston impingement and secondary atomization. Agglomerated particles will develop when combustion conditions are not favorable. Cylinder pressure data were simultaneously recorded for each film frame. Heat release data can thus be produced for each photo study. Most of the findings of earlier combustion studies on engine performance were confirmed.
An automotive powertrain includes a conventional piston engine, a continuously variable ratio transmission, an engine speed sensor and a feedback control system. The control system adjusts both the transmission ratio and the throttle valve in the engine carburetor or fuel metering system in response to the position of the accelerator pedal and in response to the crankshaft speed as measured by the engine sensor. The transmission provides extreme overdrive gear ratios which allow the engine to be operated at wide open throttle even during moderate cruising, and, in addition, the engine carburetor or fuel metering system is calibrated to deliver to the engine a stoichiometric air-fuel mixture which is combined, before combustion, with a special proportion of recirculated exhaust gas. As a result of extensive wide open throttle engine operation with the above mentioned intake charge composition, combustion variables are optimized to produce ...
X-ray diffraction enhanced imaging (DEI) is applied to inspect internal structures of weakly absorbing low-Z sample. How to extract phase information from raw images measured in different positions of rocking curve is the key problem of DEI. In this paper, we present an effective extraction method called polynomial curve fitting method, in order to extract accurate information angular in a fast speed. It is com- pared with the existing methods such as multiple-images statistical method and Gaussian curve fitting method. The experiments results on a plastic cylinder and a black ant at the Beijing Synchrotron Radiation Facility prove that the polynomial curve fitting method can obtain most approximate refraction-angle values and its computation speed is 10 times faster than the Gaussian curve fitting method. (authors)
A 206-size hybrid (ceramic/steel) cylindrical roller bearing was tested in MIL-L-23699 C oil at several speeds and loads. Heat-generation data was collected and subsequently correlated with bearing-analysis software. Bearing-cage slip data was also collected at various oil-flow rates, oil temperatures, and with both MIL-L-7808 J and MIL-L-23699 C oils. The hybrid bearing was tested in MIL-L-23699 C oil for for 25 hours at 2220 N radial load and 1.08 MDN shaft speed. The hybrid bearing technology demonstrated in the report is applicable to the Integrated High Performance Turbine Engine Technology Initiative. 15 refs.
The present paper describes the application of the commercial CFD-code FLUENT 6.1 to the numerical simulation of the flow field in a high specific speed radial fan. Two-dimensional as well as three-dimensional computations are performed using the steady 'Frozen-Rotor method' as well as the unsteady 'Sliding-Mesh method'. The predicted performance curves of the radial fan are compared with the results obtained from measurements on a test stand. Due to the relatively low computation times, the 'Frozen-Rotor method' can be used routinely for design purposes. The results of this approach can be improved if the leakage flow through the gap between the inlet nozzle and the impeller is taken into account. (orig.)
Orthogonal frequency division multiplexing (OFDM) can fully use the frequency band and transmit data at high speeds. The ADSP-TS101 is a high performance digital signal processor (DSP) with good properties that include parallel processing and a high speed. Aimed at the real-time processing requirement of the OFDM algorithm, an underwater acoustic communication system with real-time processing capability is carried out. The system is mainly composed of multiple ADSP-TS101s, a multi-channel synchronous sample module and a field programmable gate array (FPGA) chip. The multiprocessor structure is made up of a cluster/data flow associated multiprocessing parallel processing structure as the operation kernel, and a multi-channel synchronous sample module is designed to realize no phase warp amo...
Following the breakthrough for cast magnesium products, interest is now spreading to wrought applications - triggering a variety of technological questions. A major bottleneck in the manufacture of magnesium sections (profiles) by conventional hot extrusion is the low productivity, with extrusion speeds typically five to ten times lower than for comparable aluminium sections. This paper focuses on the use of hydrostatic extrusion as a means to overcome this problem. On the basis of an analytical model, it is clarified why and how process limits are affected by the process mechanics. Experimental work on the hydrostatic extrusion of the alloys M1A, ZM21 and AZ31 confirms that extrusion speed is indeed multiplied, whereas the resulting mechanical properties are similar to or better than those for conventional extrusions. (orig.)
A 46.3-ft-dia 20-degree conical ribbon parachute has been designed to retard a 2200-lb payload delivered at speeds up to 800 KCAS and at altitudes as low as 150 feet above ground level. The parachute uses both Kevlar and nylon materials, some of which were developed specifically for this parachute. The canopy design incorporates a patented construction geometry to minimize stress concentrations. A cluster of three 3.8-ft-dia ribbon parachutes is used to deploy the main parachute in the presence of severe aircraft flow field effects and large payload angles of attack. The results of over 30 full-scale flight tests indicate that fundamental limitations imposed by the dynamics of the air masses inside and behind the canopy determine the ultimate performance of a single large parachute when it is used at a release altitude of 150 ft.
Modern scientific computing involves organizing, moving, visualizing, and analyzing massive amounts of data from around the world, as well as employing large-scale computation. The distributed systems that solve large-scale problems will always involve aggregating and scheduling many resources. Data must be located and staged, cache and network capacity must be available at the same time as computing capacity, etc. Every aspect of such a system is dynamic: locating and scheduling resources, adapting running application systems to availability and congestion in the middleware and infrastructure, responding to human interaction, etc. The technologies, the middleware services, and the architectures that are used to build useful high-speed, wide area distributed systems, constitute the field of data intensive computing. This paper explores some of the history and future directions of that field.
Photoacoustic microscopy (PAM) offers label-free, optical absorption contrast. A high-speed, high-resolution PAM system in an inverted microscope configuration with a laser pulse repetition rate of 100,000 Hz and a stationary ultrasonic transducer was built. Four-dimensional in vivo imaging of microcirculation in mouse skin was achieved at 18 three-dimensional volumes per second with repeated two-dimensional raster scans of 100 by 50 points. The corresponding twodimensional B-scan (50 A-lines) frame rate was 1800 Hz, and the one-dimensional A-scan rate was 90,000 Hz. The lateral resolution is 0.23+/-0.03 ?m for Au nano-wire imaging, which is 2.0 times below the diffraction limit.
A model is presented for heat and fluid flow during hammer and anvil splat cooling. Predictions are made for the effects of superheat and hammer speed on splat thickness, cooling rate, and subsequent glass formation. The regime of Newtonian heat flow is extended well beyond the previously accepted limiting value of Nusselt number. Measurements of the structure, stability, and thickness of Fe{sub 80}B{sub 20} and Pd{sub 80}Si{sub 20} hammer and anvil splats qualitatively confirm the model prediction. Variations of superheat in shock tube splats produced similar trends to those observed in the hammer and anvil device. In an attempt to vary the equivalent of hammer speed in a shock tube device, an orifice producing a supersonic shock wave was utilized. Significant splat flake thickness reductions resulted as compared to subsonic orifices.
GPM moves from the clean room to the test chamber on a dolly without wheels. Compressed air is pumped out under airpads that float the Spacecraft on a bed of air. nThe wind generated when the centrifuge moves at its maximum speed are more than 200 mph - that's tornado speed. But since they move with the centrifuge the satellites tested only feel 20 mph winds. nLeaning outward at 45 degrees for one test orientation, GPM comes within 28 inches of the wall. When lifted onto the platform it cleared the ceiling by only five inches. nNatural audio only. nVideo Credit: Brooke Harris n
The Department of Energy decided to terminate the Flywheel Rotor and Containment Technology Development project during FY 1983. Activities this year included fabrication, inspection, and test evaluation of rotor and containment structures. A peak energy of 700 Wh was stored at an energy density of 70 Wh/kg. In cyclic tests, 10,000 cycles from design speed to half speed were logged without failure. The first test of a lightweight containment structure indicates the need for additional development. In complementary studies, production cost estimates were made for three flywheel designs. In a cooperative program with the University of Wisconsin, work began on construction of a flywheel/continuously variable transmission/heat engine car which promises fuel economy improvements of up to 100%. Suggestions are made for the direction of future work when interest in flywheel system reappears.
Experimental data on density, viscosity, and refractive index at T = (298.15, 303.15, and 308.15) K, while speed of sound values at T = 298.15 K are presented for the binary mixtures of (methylcyclohexane + benzene), methylbenzene (toluene), 1,4-dimethylbenzene (p-xylene), 1,3,5-trimethylbenzene (mesitylene), and methoxybenzene (anisole). From these data of density, viscosity, and refractive index, the excess molar volume, the deviations in viscosity, molar refraction, speed of sound, and isentropic compressibility have been calculated. The computed values have been fitted to Redlich-Kister polynomial equation to derive the coefficients and estimate the standard errors. Variations in the calculated excess quantities for these mixtures have been studied in terms of molecular interactions between the component liquids and the effects of methyl and methoxy group substitution on benzene ring.
Electrical properties of 16 keV, focused-ion-beam (FIB) (beam diameter: 1 #mu#m, current density: 50 mA/cm"2) boron-implanted silicon layers have been investigated as a function of beam scan speed and ion dose, and compared with those obtained by conventional implantation (current density: 0.4 #mu#A/cm"2). High electrical activation of the FIB implanted layers is obtained by annealing below 800"0C as a result of the increase in amorphous zones created in the implanted layers. Amorphous zone overlapping is assumed to occur at FIB implantation doses of 3 - 4 x 10"1"5 ions/cm"2 from the results of electrical activation and the carrier profile of implanted regions annealed at low temperature, if beam scan speed is lowered to about 10"-"2 cm/s. (author).
A new interest in magnesium alloys has arisen since light-weight constructions have become more and more attractive. Products that are currently available are mostly cast, forged, and extruded. A cost-effective production of sheet metals will render new perspectives in the design of light-weight constructions. The development of new casting technologies like thin slab casting or strip casting with an in-line rolling process is expected to result in a shorter processing time featuring a high potential of saving energy, time, and cost. Particular attention is paid to the casting process parameters such as casting speed and solidification speed. This article deals with some aspects of a magnesium-adapted single-belt caster. Results of casting experiments and material examination are shown as well as some advices given concerning safety and handling of liquid magnesium. (orig.)
Development testing has been conducted by Rockwell Hanford Operations (Rockwell) with simulated Fast Flux Test Facility (FFTF) Reactor fuel and unirradiated N-Reactor fuel, to identify the various problems associated with rotary shearing these fuels. This report discusses the results of tests segmenting FFTF and N-Reactor fuels using electrically driven slow-speed rotary shredders. From these tests, it has been determined that slow-speed rotary shredding of both fuels can be accomplished. Final equipment arrangements and operating parameters have been established for definitive design of the FFTF Rotary Shear. Development testing is continuing on the N-fuel rotary shear. However, it has been established that two-stage shearing is necessary and the outer N-fuel elements pose few problems, while the smaller inner elements have created numerous problems, which are being addressed.
This paper describes the experimental results of long-life solid lubricated ball bearings tested under high-vacuum of 10 exp -4 Pa, high-temperature of 300 C, and high-speed (9000 rpm) conditions. For full ball-type bearings, the thin soft metals, either Ag or Pb, which were coated on the races and balls, appeared to have good torque properties. However, the durability of such bearings was less than 300 hours. The transfer films from the lamellar solid MoS2 and metal composite retainers improved the torque and wear properties. For ceramic, i.e., silicon nitride, balls used with steel rings, wear occurred on the inner rings. All ceramic bearings with composite retainers showed improved torque and wear properties. 18 refs.
Unmanned Aerial Vehicles (UAV) are being proposed for many applications including surveillance, mapping and atmospheric studies. These applications require a lightweight, low speed, medium to long duration airplane. Due to the weight, speed, and altitude constraints imposed on such aircraft, solar array generated electric power is a viable alternative to air-breathing engines. Development of such aircraft is currently being funded under the Environmental Research Aircraft and Sensor Technology (ERAST) program. NASA Lewis Research Center (LeRC) is currently building a Solar Electric Airplane to demonstrate UAV technology. This aircraft utilizes high efficiency Applied Solar Energy Corporation (ASEC) GaAs/Ge space solar cells. The cells have been provided by the Air Force through the ManTech Office. Expected completion of the plane is early 1995, with the airplane currently undergoing flight testing using battery power.
This study performs a dynamic analysis of the rub-impact rotor supported by two couple stress fluid film journal bearings. The strong nonlinear couple stress fluid film force, nonlinear rub-impact force and nonlinear suspension (hard spring) are presented and coupled together in this study. The displacements in the horizontal and vertical directions are considered for various non-dimensional speed ratios. The numerical results show that the dynamic behaviors of the system vary with the dimensionless speed ratios, the dimensionless unbalance parameters and the dimensionless parameter, l*. Inclusive of the periodic, sub-harmonic, quasi-periodic and chaotic motions are found in this analysis. The results of this study contribute to a further understanding of the nonlinear dynamics of a rotor-...
We developed a surrogate mixture model to represent the physical properties of a coal-derived liquid fuel using only information obtained from a gas chromatography-mass spectrometry analysis of the fuel and a recently developed 'advanced distillation curve'. We then predicted the density, speed of sound, and viscosity of the fuel and compared them to limited experimental data. The surrogate contains five components (n-propylcyclohexane, trans-decalin, {alpha}-methyldecalin, bicyclohexane, and n-hexadecane), yet comparisons to limited experimental data demonstrate that the model is able to represent the density, sound speed, and viscosity to within 1, 4, and 5%, respectively. 102 refs., 2 figs., 5 tabs.
Scanning ion microscopy with polarization analysis (SIMPA) is used to study the spin-resolved surface magnetic structure of nano-sized magnetic systems. SIMPA is utilized for in situ topographic and spin-resolved magnetic domain imaging as well as for focused ion beam (FIB) etching of desired structures in magnetic or non-magnetic systems. Ultra-thin Co films are deposited on surfaces of Si(1 0 0) substrates, and ultra-thin, tri-layered, bct Fe(1 0 0)/Mn/bct Fe(1 0 0) wedged magnetic structures are deposited on fcc Pd(1 0 0) substrates. SIMPA experiments clearly show that ion-induced electrons emitted from magnetic surfaces exhibit non-zero electron spin polarization (ESP), whereas electrons emitted from non-magnetic surfaces such as Si and Pd exhibit zero ESP, which can be used to calibrate sputtering rates in situ. We report on new, spin-resolved magnetic microstructures, such as magnetic 'C' states and magnetic vortices, found at surfaces of FIB patterned magnetic elements. It is ...
Noncollinear (NC) magnetism is common in nature, especially when there exist geometrical frustration and chemical imparity in the system. In this work we studied the NC magnetism and the response to external magnetic fields in surfaces and interfaces of transition metals by using an semi-empirical tight-binding (TB) method that parameterized to the ab initio TB-LMTO calculations. We implemented this method to study two systems. The first one is the system of 6 Mn monolayers on Fe(001) substrate. Due to the complex structure and magnetic properties of Mn, we found 23 collinear magnetic configurations but only one NC configuration. The collinear ground state has a layered antiferromagnetic (AFM) coupling which agrees with previous experiments and calculations. In the NC configuration the local AFM coupling in the Mn layers is preserved, but the surface is 90 degree coupled to the substrate. Similar to the experiment in CdCr{sub 2}O{sub 4}, we obtained a collinear plateau in the NC ...
Three- and four-junction III-V devices are proposed for ultrahigh-efficiency solar cells using a new 1-eV material lattice-matched to GaAs, namely, GaInNAs. We demonstrate working prototypes of a GaInNAs-based solar cell lattice-matched to GaAs with photoresponse down to 1 eV. Under the AM1.5 direct spectrum with all the light higher in energy than the GaAs band gap filtered out, the prototypes grown with base doping of about 10{sup 17}&hthinsp;cm{sup {minus}3} have open-circuit voltages ranging from 0.35 to 0.44 V, short-circuit current densities of 1.8 mA/cm{sup 2}, and fill factors from 61{percent} to 66{percent}. To improve on the current record-efficiency tandem GaInP/GaAs solar cell by adding a GaInNAs junction, the short-circuit current density of this 1-eV cell must be significantly increased. Because these low short-circuit current densities are due to short diffusion lengths, we have demonstrated a depletion-width-enhanced variation of one of the ...
Full text: In the upper layers of the Earth's atmosphere, molecular nitrogen absorbs the extreme ultraviolet (XUV) solar radiation. The absorption is associated with dipole-allowed excitation of states of singlet ungerade symmetry ("1#SIGMA#"+_u and "1#PI#_u), which are known to undergo predissociation due to coupling with a mainfold of "1#PI#_u states. We determined new N_2 isotopic lifetimes of many "1#SIGMA#"+_u and "1#PI#_u states via line broadening measurements in the frequency domain. Ultrahigh resolution XUV + UV ionization spectra were recorded (bandwidth #approx# 250 MHz, resolving power 10"7), from which the natural linewidth, i.e. lifetime, was determined. These lifetimes provide new information about the predissociation of the singlet ungerade states in N_2. Tunable narrowband XUV radiation was produced by successively pulsed amplification of cw dye laser radiation, frequency doubling the pulsed visible laser beam into the UV and frequency tripling the ...
We present and characterize an experimental system in which we achieve the integration of an ultrahigh finesse optical cavity with a Bose-Einstein condensate (BEC). The conceptually novel design of the apparatus for the production of BECs features nested vacuum chambers and an in vacuo magnetic transport configuration. It grants large scale spatial access to the BEC for samples and probes via a modular and exchangeable ''science platform.'' We are able to produce 87Rb condensates of 5x106 atoms and to output couple continuous atom lasers. The cavity is mounted on the science platform on top of a vibration isolation system. The optical cavity works in the strong coupling regime of cavity quantum electrodynamics and serves as a quantum optical detector for single atoms. This system enables us to study atom optics on a single particle level and to further develop the field of quantum atom optics. We describe the technological modules and the operation of the combined ...
We studied the epitaxial growth of iron silicide (#epsilon#-FeSi,#beta#-FeSi_2, and #alpha#-FeSi_2) nanodots on Si (111) substrates by Fe deposition on Si nanodots on Si (111) substrates with ultrathin Si oxide films using reflection high-energy electron diffraction, scanning tunneling microscopy, and transmission electron microscope (TEM). We formed almost single phase iron silicide nanodots by controlling the Fe deposition conditions; growth temperature, deposition rate, and amount. The #epsilon#-FeSi or #alpha#-FeSi_2 nanodots were epitaxially grown in a dome shape with an average size of #approx#5 nm and an ultrahigh density (>10"1"2 cm"-"2) on the surface. We formed #approx#2-nm high and #approx#8-nm wide #beta#-FeSi_2 nanodots in a dome shape with a density of #approx#5x10"1"1 cm"-"2 on the surface. Cross-sectional TEM images revealed that the #beta#-FeSi_2 growth continued beneath the Si surface. The part of the #beta#-FeSi_2 nanodot beneath the surface ...
This patent describes a turbocharger for a two-cycle engine having an oil mist containing crankcase and burning a mixture of liquid fuel containing lubricating oil therein wherein the turbocharger comprises a shaft mounted in a housing for rotation by an exhaust-driven turbine on one end to a drive compressor on the other end connected to supply pressurized air for the fuel/air mixture of the engine, the improvement to supply lubrication to the shaft and automatically enrichen the fuel/air mixture during high speed turbocharging.
A new type of multi-channel analyzer system is introduced, which takes advantage of Universal Serial Bus to communicate with computer and gets the merit of fast speed, universality and Plug and Play. The authors discussed the framework of the system, primary functions, display of spectrum date and the way of communication with hardware. The environment of the program is Visual Basic 6.0
Ultrasound tomography is an attractive imaging method for the detection of breast cancer. The complex anatomy of the breast with its different spatial scales and material property contrasts make accurate reconstructions very challenging. This paper proposes a hybrid approach whereby Travel-of-Flight and Diffraction Tomography are combined together to achieve high-resolution and high-accuracy sound-speed reconstructions. The method is validated with several numerical phantoms.
The necessity of the electron beam machine characterization via dose measurement is discussed. It includes a measurement of comprehensive dose distribution (at known X and Z axis) for verification of the machine performance. The acquired data were then used to develop the irradiation parameters such as energy, current, distance, conveyor speed, exposure rate and depth inside product to be irradiated. These parameters will be used as a guide for the routine irradiations. (Author)
A micro-computer based fuzzy logic power system stabilizer is applied to a micro-machine system to investigate its efficiency in real time control. The stabilizing signal is determined by using measured speed or real power signals at every sampling time to damp the system oscillations. The results show the proposed stabilizer improves the system damping effectively subject to various types of disturbances.
This EPRI sponsored report describes factors that influence the selection of drives in process industry. These factors include economics, safety aspects, speed control and the plant steam balance. Since the economics play a key-role in the decision, this report provides a quick way of estimating the economics of replacing steam turbines with electric motors. The tools to carry out economic analyses have been provided in the form of graphs and nomographs for quick estimation.
The image processing system for the dynamic neutron radiography has been developed. It is based on the hardware subset, composed by the method of the pipe-line and use of algorithm of local statistics. The processing speed per one pixel is shorter than 100 n sec and video-rate processing can be executed on it. Some image processes for improving the quality of the real-time neutron image, noise reduction and contrast stretching would be attempted by the use of this system. (author).
Abstract An analytical model is developed to predict transient discharge flow into a tunnel drilled at various speeds through a heterogeneous formation. This model relies on simplifying assumptions commonly enforced in hydrogeologic engineering, and combines the convolution and superposition principles to account for composite sections with arbitrary parametric contrasts. An application to the data monitored during the exploratory drilling of an Alpine tunnel confirms the validity of the approach.
The development of electric cars always met with the difficulty in storing energy and in recovering it in the form of electric power. Research work done for the last two decades in the field of materials and of new technologies oriented mainly towards aeronautical and space applications have led to designing, realizing and experimenting with flywheels rotating at high speed in magnetic bearings. The results obtained represent openings that, now, fall in with different industrial fields and in particular with application to electric cars.
Using the experimentally determined cutoff energies of the muon-electron and the pion-electron conversion curves in a tachyon-bradyon model of the electron and the muon, the magnetic moments of these particles have been derived and found to be the Bohr magnetons identically. The tachyons, being bound to the bradyons and unable to drop below the speed of light, cause the bradyons to revolve in an orbit. It is this orbital motion of the charged bradyons that generates the magnetic moments.
This paper describes the implementations of a fuzzy logic based self-tuned controller to improve the stability of electric power systems. The stabilizing signal is computed using the standard fuzzy membership function depending on the speed/acceleration state of the generator in the phase plane. The performance of the proposed stabilizer is demonstrated by practical implementation using a digital signal processor mounted on a PC-AT. Results of the experimental tests on a physical model of a power system are presented.
Horizontal vibrations of elevator cars mainly occur because a car swings as roller guides installed at corners of a car frame move on a winding guide rail at high speeds. Rider comfort in high speed elevators is worsened by these vibrations. Conventional active dampers suppressing horizontal vibrations using ac servo motors make cars heavier so driving power becomes larger, and they are not easily applied to existing elevators. An active damping control method suited to super-high-speed elevators is which can solve these problems. The method suppresses vibrations by generating only enough magnetic force needed to suppress them only when vibrations of the car franc are produced. The vibrations are detected using acceleration detectors and magnets installed on left and right sides of the car frame. A computer simulator was made to analyze phenomena of car vibrations and to verify effects of the proposed magnetic damping ...
A special purpose hardware machine, which simulates up to one half-million gates and 2m byte RAM ICS at a 5 millisecond clock speed is described. This is accomplished with a hardware logic (HAL) simulator. This performance is achieved with 32 distributed special parallel processors, which utilize block oriented simulation technique. The technique promises a good cost hardware logic simulator. 7 references.
This patent describes a gas-diesel dual fuel engine apparatus having a diesel engine, a diesel fuel supply system including a diesel fuel injection pump, a gaseous fuel supply system including gaseous fuel regulating valve, and a governing and controlling device for governing the speed of the engine and controlling the switchover of the operation of the engine between a diesel fuel mode and a gaseous fuel mode.
The Flux Mapping System (FMS) of 540 MWe PHWR is a system, which is first of its kind used in Indian PHWRs. It is used to compute a detailed flux/power distribution of the reactor core using modal synthesis method .The paper brings out the high availability features of FMS and the software design philosophy. The paper emphasizes on framework based reusable architectural design, which simplifies and speeds up the development of data acquisition systems. (author)
Electric cars run silently and produce no exhaust fumes. In cooperation with other companies BBC has developed a compact drive system for the VW Golf comprising a battery-powered separately excited DC motor, transmission, control system and setpoint devices. With a range of 57 km and a top speed of 90 km/h, the electric Golf lends itself well to city driving.
Characterization of the electron beam's properties will be a major task after the upgrade of the Los Alamos Free-Electron Laser (FEL) Facility with a photoelectric injector (PEI) and increased acceleration capability to 40 MeV. Adjustments to the previous diagnostics package that address the lower beam emittance, higher energy, and wakefield source reduction issues will be discussed. 6 refs., 8 figs., 1 tab.
In addition to their use in high-speed ovens, microwaves are also finding applications in industrial manufacture, quality control and storage - anywhere where the high-frequency transmission or reflection properties of a material can be exploited. Microwaves are also being used in medical applications for the characterization of certain type of tumours. They are also being used in research into ultrasonic cavitation. (authors) 5 refs.
The basic function of a Power System Stabilizer (PSS) is to add damping to the generator rotor oscillations by controlling its excitation using auxiliary stabilizing signals. To provide damping, the stabilizer must produce a component of electrical torque in phase with the rotor speed deviations. This paper introduces the hardware specifications and various functions of microprocessor (TMS320C32)-based digital PSS to provide the damping torque. (author). 3 refs., 6 figs.
Here, we consider a recent paper concerned with magnetic braking by induced currents (Ireson and Twidle 2008 Eur. J. Phys. 29 745-51). Our objective is to elucidate why measurement of speed in which a magnet is dropped through a non-ferromagnetic conductive tube depends on its geometry in a non-monotonic way, which was not clearly explained by the authors. (letters and comments)
The acceptances to be obtained during the first operational run, refer to measures proving the functional integrity of the turbine control system and assuring the compliance with the maximum allowable overspeed in case of lead changes or perturbations. The Guideline concerns essentially speed, power, and pressure controllers coupled to generators. It may be appropriately extended to steam turbines serving other purposes.
Safety-related instrument in nuclear power plants must be checked for reliability over their projected operating life. A method of conducting accelerated aging tests is presentd. It uses the Arrhenius activation energy concept and manipulation of the parameters of the test e.g. by raising test temperature, by relying on a model characterizing the chemical-related reactions of materials.
An eddy current probe of the level of molten metal is considered for a sectional machine of continuous casting of steel. The advantages of electromagnetic probes of the level over radiometric ones lie in their insensitivity to the layer of dross and high speed. The results and directions of further studies are given.
This paper proposes a novel control strategy for tracking peak power in a wind or wave energy system using a squirrel cage induction generator. It eliminates wind speed measurement or estimation and uses a simple scalar technique by exploiting the cubic nature of the power curve. The method works even when air velocity is varying dynamically. (author)
Laser-Doppler anemometry was used to investigate mean flow and turbulence fields in a direct injection diesel engine, motored at speeds of 1500, 2250 and 3000 rev/min. Both cycle-resolved and ensemble-averaged measurements were made in the upper part of the cylinder during the inlet and compression strokes. The cycle-resolved measurements in the inlet stroke are discussed in this paper.
We solve the loop equations of the $\\beta$-ensemble model analogously to the solution found for the Hermitian matrices $\\beta=1$. For \\beta=1$, the solution was expressed using the algebraic spectral curve of equation $y^2=U(x)$. For arbitrary $\\beta$, the spectral curve converts into a Schr\\"odinger equation $((\\hbar\\partial)^2-U(x))\\psi(x)=0$ with $\\hbar\\propto (\\sqrt\\beta-1/\\sqrt\\beta)/N$. This paper is similar to the sister paper~I, in particular, all the main ingredients specific for the algebraic solution of the problem remain the same, but here we present the second approach to finding a solution of loop equations using sectorwise definition of resolvents. Being technically more involved, it allows defining consistently the B-cycle structure of the obtained quantum algebraic curve (a D-module of the form $y^2-U(x)$, where $[y,x]=\\hbar$) and to construct explicitly the correlation functions and the corresponding symplectic ...
Variations in skin perfusion are easily detected by laser speckle contrast maps, but a robust interpretation of the information has been lacking. We show that multiple-exposure laser speckle methods produce the same spectral information as laser Doppler methods when applied to targets with embedded moving scatterers. This enables laser speckle measurements to be interpreted more quantitatively. We do this by using computer simulation of speckle data, and by experimental measurements on Brownian motion and skin perfusion using a laser Doppler system and a multiple-exposure laser speckle system. The power spectral density measurements of the light fluctuations derived using both techniques are exactly equivalent. Dermal perfusion can therefore be measured by laser Doppler or laser speckle contrast methods. In particular, multiexposure laser speckle can be rapidly processed to generate a full-field map of the perfusion index proportional to the ...
Indoline dye sensitizers were designed and studied theoretically to increase molar extinction coefficients in the visible to near infrared region for solar-cell devices. To gain insight into dye sensitizers' structural, electronic, and optical properties, DFT/TDDFT calculations were performed on a series of dye sensitizers derived from the D149. The good agreement between the experimental and TDDFT calculated absorption spectra of the D149 sensitizer allowed us to provide a detailed assessment of the main spectral features of a series of dye sensitizers. Increase in the conjugation length resulted in a more red-shifted spectral response and less positive oxidation potential than that of the D149. The dye with the dimethylfluorene group showed stronger absorption bands due to a large dipole moment. The calculated dipoles for the dye series correlate well with the observed strong absorption bands of the electronic spectra. These results provided ...
We study the spectral and temporal behavior of the High Mass X-ray Binary A 0535+26 during a `pre-outburst flare' which took place ~5 d before the peak of a normal (type I) outburst in August/September 2005. We compare the studied behavior with that observed during the outburst. We analyse RXTE observations that monitored A 0535+26 during the outburst. We complete spectral and timing analyses of the data. We study the evolution of the pulse period, present energy-dependent pulse profiles both at the initial pre-outburst flare and close to outburst maximum, and measure how the cyclotron resonance-scattering feature (hereafter CRSF) evolves. We present three main results: a constant period P=103.3960(5)s is measured until periastron passage, followed by a spin-up with a decreasing period derivative of Pdot=(-1.69+/-0.04)x10^(-8)s/s at MJD 53618, and P remains constant again at the end of the main outburst. The spin-up provides evidence for the ...
During searches for new optical Galactic supernova remnants (SNRs) in the high resolution, high sensitivity Anglo-Australian Observatory/United Kingdom Schmidt Telescope (AAO/UKST) HAlpha survey of the southern Galactic plane, we uncovered a variety of filamentary and more diffuse, extensive nebular structures in the vicinity of Wolf-Rayet (WR) star 48 (Theta Muscae), only some of which were previously recognised. We used the double-beam spectrograph of the Mount Stromlo and Siding Spring Observatory (MSSSO) 2.3-m to obtain low and mid resolution spectra of selected new filaments and structures in this region. Despite spectral similarities between the optical spectra of WR star shells and SNRs, a careful assessment of the new spectral and morphological evidence from our deep HAlpha imagery suggests that the putative shell of Theta Mus is not a WR shell at all, as has been commonly accepted, but is rather part of a more complex area of ...
(abridged) The accretion disk in AGN is expected to produce strong outflows, in particular a UV-line driven wind. Despite providing a good fit to the data, current spectral models of the X-ray spectrum of AGN observed through an accretion disk wind are ad-hoc in their treatment of the properties of the wind material. In order to address these limitations we adopt a numerical computation method that links a series of radiative transfer calculations, incorporating the effect of a global velocity field in a self-consistent manner (XSCORT). We present a series of example spectra from the XSCORT code that allow us to examine the shape of AGN X-ray spectra seen through a wind, for a range of velocity and density distributions, total column densities and initial ionization parameters. These detailed spectral models clearly show considerable complexity and structure that is strongly affected by all these factors. The presence of sharp features in the ...
In a recent survey of the stellar populations of LINERS and LINER/HII Transition Objects (TOs) we identified a numerous class of nuclei which stand out because of their conspicuous 10^8-9 yr populations. These objects were called ``Young-TOs'', since they all have TO-like emission line ratios. In this paper we investigate the radial variations of spectral properties in Low Luminosity AGN. Our analysis is based on high S/N, 3500-5500 A, long-slit spectra for 47 galaxies. The data probe distances of typically up to 850 pc from the nucleus with a resolution of ~ 100 pc and S/N ~ 30. Stellar population gradients are mapped by the radial profiles of absorption line equivalent widths and colours along the slit. These variations are further analyzed by means of a decomposition of each spectrum in terms of template galaxies representative of very young (<= 10^7 yr), intermediate age (10^8-9 yr) and old (10^10 yr) populations. Our main findings are: (1) Significant ...
We present a spectroscopic catalog of 70,841 visually inspected M dwarfs from the seventh data release of the Sloan Digital Sky Survey (SDSS). For each spectrum, we provide measurements of the spectral type, a number of molecular bandheads, and the H-alpha, H-beta, H-gamma, H-delta and Ca II K emission lines. In addition, we calculate the metallicity-sensitive parameter zeta and identify a relationship between zeta and the g-r and r-z colors of M dwarfs. We assess the precision of our spectral types (which were assigned by individual examination), review the bulk attributes of the sample, and examine the magnetic activity properties of M dwarfs, in particular those traced by the higher order Balmer transitions. Our catalog is cross-matched to Two Micron All Sky Survey (2MASS) infrared data, and contains photometric distances for each star. Lastly, we identify eight new late-type M dwarfs that are possibly within 25 pc of the Sun. Future studies ...
The near infrared (NIR) upgrade to the Robert Stobie Spectrograph (RSS) on the Southern African Large Telescope (SALT), RSS/NIR, extends the spectral coverage of all modes of the visible arm. The RSS/NIR is a low to medium resolution spectrograph with broadband imaging, spectropolarimetric, and Fabry-Perot imaging capabilities. The visible and NIR arms can be used simultaneously to extend spectral coverage from approximately 3200 A to 1.6 um. Both arms utilize high efficiency volume phase holographic gratings via articulating gratings and cameras. The NIR camera is designed around a 2048x2048 HAWAII-2RG detector housed in a cryogenic dewar. The Epps optical design of the camera consists of 6 spherical elements, providing sub-pixel rms image sizes of 7.5 +/- 1.0 um over all wavelengths and field angles. The exact long wavelength cutoff is yet to be determined in a detailed thermal analysis and will depend on the semi-warm instrument cooling ...
A curved crystal X-ray spectrographs of reflection type spherical geometry was required based on the Johann scheme. Due to their high efficiency and resolution, X-ray spectrographs of focusing spectrograph spatial resolution are suitable for detecting weak X-ray spectra in spectrometers for laser fusion research. Spherically bent mica crystal with a radius of curvature of 380 mm was used in the spectrometer. The Bragg angle of the crystal analyzer was 51 degree. The image plate was employed to obtain high spatial resolution and a narrow spectral band width, with an effective area of 30 mm x 80 mm. The designed optical path of the X-ray spectrometer beam was 980 mm long from the source to the crystal and the detector. The first experiment was carried out at the 20 J energy laser facility of Research Center of Laser Fusion, China Academy of Engineering Physics. X-ray spectra in an absolute intensity scale were obtained from Al laser-produced plasmas created by laser ...
We provide a numerically efficient procedure to perform LDA+Hubbard I calculations including self-consistency over the charge density in the FP-LAPW basis. The method is applied to Pu, Am, and PuAm and PuCe alloys. Our results for valence photoemission spectra (PES) agree with experimental data and with previous LDA+DMFT calculations. Analysis of the J=5/2 and J=7/2 contributions to the f-occupation supports the intermediate-coupling picture of f-states in heavy actinides. The electronic specific heat coefficient is calculated for PuAm and PuCe alloys in reasonable agreement with recent experiments. We show that Pu atoms keep their mixed-valence character in these alloys. Next, we study electronic and spectral properties of Pu-based superconductor PuCoGa_5 and obtain good agreement with experimental PES. Finally, we analyze surface effects. In Pu monolayer, we find substantial modification of PES due to 5f-electron localization consistent with experimental ...
The spectral energy-dependence of the radiation-induced ESR signal has been studied in ovine cortical bone. Crushed bone samples were irradiated using photon beams with effective energies in the range from 0.06 to 6 MeV, and electron beams with mean energies in the range from 2 to 10 MeV. The photon and electron data were normalized to a dose to bone of 50 Gy and the results are reported as response relative to the ESR signal for photon irradiation at 1.25 MeV ("6"0Co). The photon irradiation results show that the ESR response is greatest at low energies with a relative value of 1.2 at 0.06 MeV. The relative response decreases, as the energy increases, to approximately 0.85 in the region of 2 to 3 MeV. These variations in the relative ESR responses are significantly less than the ESR energy-dependent responses reported in the literature for human tooth enamel and synthetic hydroxyapatite. An explanation for this difference is offered. For electron beam ...
The cold-worked Zr-2.5%Nb alloy is used as material for the pressure tubes in CANDU nuclear reactors. During the service life in reactor, diffusion of hydrogen and/or deuterium in the pressure tubes wall occur. Below a certain temperature, a stable hydride of zirconium is formed, as a brittle phase which can lead to catastrophic failures. For this reason, it is very important to be able to investigate the hydrogen effect on the micro structural properties of zirconium alloys. In the present paper a non-destructive testing technique is used, known as ultrasonic spectral analysis. When an ultrasonic signal traverses a medium, the frequency components associated with the input signal are altered. By frequency analysing the reflected signals, it is possible to study and compare the material properties. The two major parameters measured in ultrasonic spectroscopy are the attenuation and the velocity of the waves. Attenuation is determined by the energy losses in ...
The second list of objects in the Second Biurakan Spectral Sky Survey of the region centered on alpha 09h50m, delta +55 deg 00 arcmin is given. The list contains data on 110 objects and galaxies of a peculiar physical nature and 24 blue stars. The observations were made with the 40-52 arcsec Schmidt telescope of the Biurakan Astrophysical Observatory with a set of three objective prisms using Kodak IIIaJ and IIIaF emulsions sensitized in nitrogen. The area is found to contain 20 quasar candidates and four Seyfert galaxies, 27 blue stellar objects, 24 galaxies with an appreciable ultraviolet continuum, and 39 emission galaxies without appreciable ultraviolet radiation. The surface brightness of the quasars and Seyferts on the considered area down to the limiting magnitude 19.5 M is more than 1.5 per square degree with allowance for the already known quasars. The surface density of emission galaxies is about four per square degree. 7 references.
The principal paradigm for gamma-ray bursts (GRBs) suggests that the prompt transient gamma-ray signal arises from multiple shocks internal to the relativistic expansion. This paper explores how GRB prompt emission spectra can constrain electron (or ion) acceleration properties at the relativistic shocks that pertain to GRB models. The array of possible high-energy power-law indices in accelerated populations is highlighted, focusing on how spectra above 1 MeV can probe the field obliquity in GRB internal shocks, and the character of hydromagnetic turbulence in their environs. When encompassing the MeV-band spectral break, fits to BATSE/EGRET burst data indicate that the preponderance of electrons responsible for the prompt emission reside in an intrinsically non-thermal population. This differs markedly from typical populations generated in acceleration simulations; potential resolutions of this conflict such as the action of self-absorption are mentioned. ...
A spectral element method embodying Large Eddy Simulation based on Re- Normalization Group theory for simulating Sub Grid Scale viscosity was chosen for this work. This method is embodied in a computer code called NEKTON. NEKTON solves the unsteady, 2D or 3D,incompressible Navier Stokes equations by a spectral element method. The code was later extended to include the variable density and multiple reactive species effects at low Mach numbers, and to compute transport of large particles governed by inertia. Transport of small particles is computed by treating them as trace species. Code computations were performed for a number of test conditions typical of flow past a deep tube bank in a boiler. Results indicate qualitatively correct behavior. Predictions of deposition rates and deposit shape evolution also show correct qualitative behavior. These simulations are the first attempts to compute flow field results at realistic flow Reynolds numbers ...
Reflectance anisotropy spectroscopy (RAS) has been used, together with scanning tunnelling spectroscopy (STS), to investigate the optical and electronic properties of nanodots formed by depositing Ag on the Si(111)-3 x 1-Ag surface. One-dimensional (1D) arrays of nanodots were grown on a single-domain (3 x 1)-Ag surface and the anisotropic optical response in the 0.5-5 eV range measured by RAS. Aligned, elongated Ag islands were also grown on this surface to compare their properties with those of the nanodots. STS of the Ag islands showed distinct metallic behaviour, whereas the nanodots revealed a bandgap of #approx#0.6 eV, indicating that the surface of the dots has a non-metallic character, similar to that of the Si(111)-3 x 1-Ag surface. RAS also showed substantial differences between the structures, with a large infrared anisotropy for the metallic Ag islands consistent with anisotropic Drude-like intraband transitions, whereas the nanodots gave a negligible response in this ...
We review results from general relativistic axisymmetric magnetohydrodynamic simulations of accretion in Sgr A*. We use general relativistic radiative transfer methods and to produce a broad band (from millimeter to gamma-rays) spectrum. Using a ray tracing scheme we also model images of Sgr A* and compare the size of image to the VLBI observations at 230 GHz. We perform a parameter survey and study radiative properties of the flow models for various black hole spins, ion to electron temperature ratios, and inclinations. We scale our models to reconstruct the flux and the spectral slope around 230 GHz. The combination of Monte Carlo spectral energy distribution calculations and 230 GHz image modeling constrains the parameter space of the numerical models. Our models suggest rather high black hole spin ($a_*\\approx 0.9$), electron temperatures close to the ion temperature ($T_i/T_e \\sim 3$) and high inclination angles ($i \\approx 90 \\deg$).
This paper presents a nonlinear Bayesian regression algorithm for the purpose of detecting and estimating gas plume content from hyper-spectral data. Remote sensing data, by its very nature, is collected under less controlled conditions than laboratory data. As a result, the physics-based model that is used to describe the relationship between the observed remotesensing spectra, and the terrestrial (or atmospheric) parameters that we desire to estimate, is typically littered with many unknown "nuisance" parameters (parameters that we are not interested in estimating, but also appear in the model). Bayesian methods are well-suited for this context as they automatically incorporate the uncertainties associated with all nuisance parameters into the error estimates of the parameters of interest. The nonlinear Bayesian regression methodology is illustrated on realistic simulated data from a three-layer model for longwave infrared (LWIR) measurements from a passive ...
A recent study reported the results of an exploratory study of alterations of the quantitative sleep profile due to the effects of a digital mobile radio telephone. Rapid eye movement (REM) was suppressed, and the spectral power density in the 8--13 Hz frequency range during REM sleep was altered. The aim of the present study was to illuminate the influence of digital mobile radio telephone on the awake electroencephalogram (EEG) of healthy subjects. For this purpose, the authors investigated 34 male subjects in a single-blind cross-over design experiment by measuring spontaneous EEGs under closed-eyes condition from scalp positions C{sub 3} and C{sub 4} and comparing the effects of an active and an inactive digital mobile radio telephone (GSM) system. During exposure of nearly 3.5 min to the 900 MHz electromagnetic field pulsed at a frequency of 217 Hz and with a pulse width of 580 {micro}s, the authors could not detect any difference in the awake EEGs in terms of ...
Radiowave scintillation in the presence of ionospheric disturbances has the potential to disrupt numerous transionospheric radio and radar systems. This report describes development of a model characterizing the plasma density irregularities that produce scintillation in the naturally disturbed mid-latitude F layer. The model will be incorporated into Program WBMOD, which includes subroutines for computing both link geometry and scintillation indices, the latter by means of phase screen diffraction theory. Earlier versions of WBMOD, were based on extensive analysis of scintillation data collected in the auroral and equatorial zones in Wideband Satellite Mission. The model described herein is based on similarly extensive analysis of Wideband data from one mid latitude station and of data collected from HiLat satellite at another mid latitude station. The model describes irregularities at an effective height of 350 km that are isotropic across the geomagnetic field and elongated by a ...
Large area, single-element Si(Li) detectors have been fabricated using a novel geometry which yields detectors with reduced capacitance and hence reduced noise at short amplifier pulse-processing times. A typical device employing the new geometry with a thickness of 6 mm and an active area of 175 mm 2 has a capacitance of only 0.5 pf, compared to 2.9 pf for a conventional planar device with equivalent dimensions. These new low capacitance detectors, used in conjunction with low capacitance field effect transistors, will result in x-ray spectrometers capable of operating at very high count rates while still maintaining excellent energy resolution. The spectral response of the low capacitance detectors to a wide range of x-ray energies at 80 K is comparable to typical state-of-the-art conventional Si(Li) devices. In addition to their low capacitance, the new devices offer other advantages over conventional detectors. Detector fabrication procedures, I-V and C-V ...
A method for quick, high-accuracy measurement of lithium isotopes has become necessary in carrying out research on the separation and concentration of lithium isotopes by ion exchange. The present report focuses on the application of a hollow cathode, as excitation source, to emission spectral analysis for lithium isotope measurement. The grating monochromator used incorporates a pressure scanned etalon. With decreased Doppler broadening and pressure broadening, the hollow cathode, used as excitation source, can give narrow spectral lines, permitting good separation among them. To achieve a high accuracy, the emission intensity of the hollow cathode should be maintained as stable as possible relative to time. In particular, the stability of a light source can be affected significantly by the chemical form of the sample. A study is also made here to identify a condition where lithium acetate effluent as-obtained from an ion exchange column can ...
Characteristics of inertia gravity waves associated with convection are investigated in the lower stratosphere using high-resolution radiosonde data observed from 18 June to 15 July of 2005 and 2007 in Korea. Three-dimensional ray-tracing model and reanalysis data are used to investigate the propagation and the sources of the observed waves. The observed waves associated with convections are discriminated based on the existence of convections when and where the rays reach the average height range of convective clouds. Waves observed in 2005 and 2007 show similar spectral characteristics, but wave energy in 2007 is significantly larger than in 2005. The observed waves propagate from three source regions: the northeastern, southeastern, and western regions around Korea. They show preferential propagation directions based on their sources, and convections from the western region generate larger-amplitude gravity waves than the other two regions. The ...
We investigate the spectral and temporal behavior of the high mass X-ray binary Vela X-1 during a phase of high activity, with special focus on the observed giant flares and off states. INTEGRAL observed Vela X-1 in a long almost uninterrupted observation for two weeks in 2003 Nov/Dec. The data were analyzed with OSA 7.0 and FTOOLS 6.2. We derive the pulse period, light curves, spectra, hardness ratios, and hardness intensity diagrams, and study the eclipse. In addition to an already high activity level, Vela X-1 exhibited several intense flares, the brightest ones reaching a maximum intensity of more than 5 Crab in the 20-40 keV band and several off states where the source was no longer detected by INTEGRAL. We determine the pulse period to be 283.5320+/-0.0002 s, which is stable throughout the entire observation. Analyzing the eclipses provided an improvement in the ephemeris. Spectral analysis of the flares indicates that there appear to be ...
The dependencies that limit high frequency operation of a vacuum microelectronic grating free-electron laser are examined. The important parameters are identified as the electron beam energy, emittance, and generalized perveance. The scaling of power with emittance and frequency is studied in the far-infrared spectral range using a modified scanning electron microscope (SEM) and submillimeter diffraction gratings. The SEM is suited to the task of generating and positioning a low emittance (10"-"2#pi#-mm-mrad), low current (100 #mu#A), but high current density (50-500 A cm"-"2) electron beam. It has been used to demonstrate the spontaneous emission process known as the Smith-Purcell effect. A vacuum microelectronic grating free-electron laser has the potential of generating radiation throughout the entire far-infrared spectral range which extends from approximately 10 to 10"3#mu#m. An introduction to the theory, initial results, and details of ...
HD 100453 has an IR spectral energy distribution (SED) which can be fit with a power-law plus a blackbody. Previous analysis of the SED suggests that the system is a young Herbig Ae star with a gas-rich, flared disk. We reexamine the evolutionary state of the HD 100453 system by refining its age (based on a candidate low-mass companion) and by examining limits on the disk extent, mass accretion rate, and gas content of the disk environment. We confirm that HD 100453B is a common proper motion companion to HD 100453A, with a spectral type of M4.0V - M4.5V, and derive an age of 10 +/- 2 Myr. We find no evidence of mass accretion onto the star. Chandra ACIS-S imagery shows that the Herbig Ae star has L_X/L_Bol and an X-ray spectrum similar to non-accreting Beta Pic Moving Group early F stars. Moreover, the disk lacks the conspicuous Fe II emission and excess FUV continuum seen in spectra of actively accreting Herbig Ae stars, and from the FUV ...
The phase transition behaviour of polyethylene-b-poly(ethylene oxide) (PE-b-PEO) diblock copolymer with relatively short chain lengths has been studied on the basis of temperature dependent infrared and Raman spectral measurements and synchrotron WAXD/SAXS simultaneous measurements, from which the concrete structural changes were deduced successfully from the various levels of molecular chain conformation, chain packing mode and higher-order structure. The higher-order structure has been found to transform between lamella, perforated lamella, gyroid, cylinder and sphere structures. The inner structural changes occurring in the polyethylene and poly(ethylene oxide) parts have been related with these morphological changes. The morphological transition from lamella to gyroid occurs with keeping the crystalline state of polyethylene parts. This apparently curious transition can be interpreted reasonably by assuming the thermally-activated chain motion in the crystal ...
Displacements per atom (DPA) is a widely used damage unit for displacement damage in nuclear materials. Calculating the DPA for SiC irradiated in a particular facility requires a knowledge of the neutron spectrum as well as specific information about displacement damage in that material. In recent years significant improvements in displacement damage information for SiC have been generated, especially the energy required to displace an atom in an irradiation event and the models used to describe electronic and nuclear stopping. Using this information, numerical solutions for the displacement functions in SiC have been determined from coupled integro-differential equations for displacements in polyatomic materials and applied in calculations of spectral-averaged displacement cross sections for SiC. This procedure has been used to generate spectrally averaged displacement cross sections for SiC in a number of reactors used for radiation damage ...
Displacements per atom (DPA) is a widely used damage unit for displacement damage in nuclear materials. Calculating the DPA for SiC irradiated in a particular facility requires a knowledge of the neutron spectrum as well as specific information about displacement damage in that material. In recent years significant improvements in displacement damage information for SiC have been generated, especially the energy required to displace an atom in an irradiation event and the models used to describe electronic and nuclear stopping. Using this information, numerical solutions for the displacement functions in SiC have been determined from coupled integro-differential equations for displacements in polyatomic materials and applied in calculations of spectral-averaged displacement cross sections for SiC. This procedure has been used to generate spectrally averaged displacement cross sections for SiC in a number of reactors used for radiation damage ...
A solar water splitting cell composed of WO3, Polymer Electrolyte Membrane (PEM) and Pt was constructed for producing hydrogen from deionized water in sunlight. Spectral responsivity measurements under various temperatures and bias voltages were conducted for the cell using the Incident Photon to Current Efficiency (IPCE) method. For comparison, a known WO3 Photo Electro Chemical (PEC) cell containing H3PO4 electrolyte, WO3/H3PO4/Pt, was tested using the same test method. The WO3/PEM-H2O/Pt cell showed better Quantum Efficiency (QE) performance compared to that obtained from the cell with the chemical electrolyte. For the first time, spectral responsivity of photo water splitting process without bias power was unveiled in the new WO3 cell, demonstrating the self-sustained photo electrolysi...
The theory of a method of determination of reactivity from power spectral density measurements with /sup 252/Cf and the results of experiments with a critical assembly mockup of a liquid-metal fast breeder reactor (LMFBR) and with uranium (93.2 wt % /sup 235/U) metal cylinders and a sphere are presented. This method of reactivity determination has an advantage over existing methods in that it determines the reactivity only from properties of the reactor at the subcritical state of interest and thus does not require a calibration near delayed criticality. In these experiments, the reactivity was varied by changing the fissile loading or the amount of neutron absorber inserted; for the LMFBR mockup, the reactivity varied to approximately 75 dollars subcritical, and for the uranium metal assemblies to approximately 30 dollars subcritical. These experiments verified for the first time the predictions of theory that could be tested in the measurements. This method has ...
The consistency of different instruments and methods for measuring two-dimensional (2D) power spectral density (PSD) distributions are investigated. The instruments are an interferometric microscope, an atomic force microscope (AFM) and the X-ray Reflectivity and Scattering experimental facility, all available at Lawrence Berkeley National Laboratory. The measurements were performed with a gold-coated mirror with a highly polished stainless steel substrate. It was shown that these three techniques provide essentially consistent results. For the stainless steel mirror, an envelope over all measured PSD distributions can be described with an inverse power-law PSD function. It is also shown that the measurements can be corrected for the specific spatial frequency dependent systematic errors of the instruments. The AFM and the X-ray scattering measurements were used to determine the modulation transfer function of the interferometric microscope. The corresponding ...
The flux of cosmic ray antiprotons with kinetic energies between /approximately/1 and 15 GeV is /approximately/5 times greater than the flux predicted on the basis of the leaky-box model. This excess is attributed to secondary antineutron production in compact sources. Because the antineutrons are not confined by the magnetic field of the compact source, they leave the interaction site, decay in interstellar space and account for the apparent excess cosmic ray antiproton flux. The escape and decay of neutrons produced in association with the antineutrons is a source of cosmic ray protons. Observations of the angular variation of the intensity and spectral shape of 100 MeV ..gamma..-rays produced by neutron-decay protons in the reaction p + p ..-->.. ..pi../sup 0/ ..-->.. 2..gamma.. could reveal compact-source cosmic ray production sites. COS-B observations of spectral hardening near point sources, and future high-resolution observations ...
A method for determining the reactivity of subcritical systems of fissile material, using neutron-noise power spectral density measurements in conjunction with a /sup 252/Cf source, has been tested in experiments with an aqueous solution containing uranium fluoride (4.95 wt% /sup 235/U). The kappasub(eff)-values obtained from the ratio of spectral densities G*/sub 12/G/sub 13//G/sub 11/G/sub 23/ agreed with those from break-frequency noise analysis and with bias-corrected transport theory calculations within the statistical uncertainty of the measurements. Corrections for the effects of spatial modes and source-detector locations appear to be well-understood, since measurements for a variety of source-detector positions resulted in essentially the same kappasub(eff)-values. Modal correction factors were such that ignoring them would result in higher values of kappasub(eff) than actually occur. The measurements have demonstrated the ...
The results of experimental measurements and theoretical simulations of circular dichroism in the angular distribution (CDAD) of photoemission from atomic core levels of each of the enantiomers of a chiral molecule, alanine, adsorbed on Cu(1 1 0) are presented. Measurements in, and out of, substrate mirror planes allow one to distinguish the CDAD due to the chirality of the sample from that due to a chiral experimental geometry. For these studies of oriented chiral molecules, the CDAD is seen not only in photoemission from the molecular chiral centre, but also from other atoms which have chiral geometries as a result of the adsorption. The magnitude of the CDAD due to the sample chirality differs for different adsorption phases of alanine, and for different emission angles and energies, but is generally small compared with CDAD out of the substrate mirror planes which is largely unrelated to the molecular chirality. While similar measurements of other molecules may reveal larger CDAD ...
The spectral properties of Lyman break galaxies (LBGs) offer a means to isolate pure samples displaying either dominant Ly-alpha in absorption or Ly-alpha in emission using broadband information alone. We present criteria developed using a large z ~ 3 LBG spectroscopic sample from the literature that enables large numbers of each spectral type to be gathered in photometric data, providing good statistics for multiple applications. In addition, we find that the truncated faint, blue-end tail of z ~ 3 LBG population overlaps and leads directly into an expected Ly-alpha emitter (LAE) population. As a result, we present simple criteria to cleanly select large numbers of z ~ 3 LAEs in deep broadband surveys. We present the spectroscopic results of 32 r' <~ 25.5 LBGs and r' <~ 27.0 LAEs at z ~ 3 pre-selected in the Canada-France-Hawaii Telescope Legacy Survey that confirm these criteria.
Over the last decade {\\it ab initio} modeling of material properties has become widespread in diverse fields of research. It has proved to be a powerful tool for predicting various properties of matter under extreme conditions. We apply modern computational chemistry and materials science methods, including density functional theory (DFT), to solve lingering problems in the modeling of the dense atmospheres of cool white dwarfs ($T_{\\rm eff}\\rm <7000 \\, K$). Our work on the revision and improvements of the absorption mechanisms in the hydrogen and helium dominated atmospheres resulted in a new set of atmosphere models. By inclusion of the Ly-$\\rm \\alpha$ red wing opacity we successfully fitted the entire spectral energy distributions of known cool DA stars. In the subsequent work we fitted the majority of the coolest stars with hydrogen-rich models. This finding challenges our understanding of the spectral evolution of cool white ...
We construct models for gamma-ray bursts where the emission comes from internal shocks in a relativistic wind with a highly non uniform distribution of the Lorentz factor. We follow the evolution of the wind using a very simplified approach where a large number of layers interact by direct collisions but where all pressure waves have been suppressed. We suppose that the magnetic field and the electron Lorentz factor reach large equipartition values in the shocks. Synchrotron photons emitted by the relativistic electrons have a typical energy in the gamma-ray range in the observer frame. Synthetic bursts are constructed as the sum of the contributions from all the internal elementary shocks and their temporal and spectral properties are compared to the observations. We reproduce the diversity of burst profiles, the ``FRED'' shape of individual pulses and the short time scale variability. Synthetic bursts also satisfy the duration-hardness relation and individual ...
The vortex-excited dynamics of a uniform pivoted cylinder in uniform and sheared flow was investigated experimentally. The experiments were numerically simulated using a diffusive Van der Pol oscillator model developed by Balasubramanian & Skop recently. Salient features of the experimental investigations and the numerical simulations are presented here. Comparisons between the experimentally recorded and numerically predicted structural response to vortex-excited vibrations, power spectral density measurements of near-wake velocity fluctuations and lock-in ranges are made. A comparison of the numerical predictions and the experimental data reveals good agreement.
Paeciloxocins A and B (2-(1-hydroxy-3-methylbutyl)- and 2-(1-acetoxy-3-methylbutyl)- 11-hydroxy-9-methyl-1-methoxy-5H,7H-dibenzo[b,g]-1,5-dioxocin-5-ones), viz., two new metabolites, were isolated from the mangrove fungus Paecilomyces sp. collected from the Taiwan Strait. Their structures were elucidated by spectral methods. Paeciloxocin A exhibited strong cytotoxicity against the hepG2 cell line.
The authors present the emitter efficiency results for the thin film 25 percent Ho YAG (Yttrium Aluminum Garnet, Y3Al5O12) selective emitter from 1000 to 1700 K with a platinum substrate. Spectral emittance and emissive power measurements were made (1.2 less than lambda less than 3.2 microns) and used to calculate the radiative efficiency. The radiative efficiency and power density of rare earth doped selective emitters are strongly dependent on temperature and experimental results indicate an optimum temperature (1650 K for Ho YAG) for thermophotovoltaic (TPV) applications.
Search for the value of ?13 mixing angle is of importance in understanding the lepton flavor mixing matrix, and in motivating future experiments to probe CP violation in the lepton sector. Among the present experimental approaches, reactor experiment can provide a clean laboratory for the ?13-measurement. The Daya Bay experiment will start civil construction this year at Daya Bay, Guangdong, China. The goal of this experiment is to reach a sensitivity in sin2 2?13 of < 0.01 at 90% C.L. by precisely measuring the disappearance and spectral distortion of reactor electron anti-neutrinos with multiple identical detectors at different baselines. The talk will present the current status and prospects of the experiment.
Syntheses of all five of the singly labeled (/sup 15/N)adenines are now provided. The presence or absence of two-bond /sup 15/N-/sup 1/H spin couplings in their /sup 1/H NMR spectra confirm the location of the isotope in each case. The fragmentation patterns in their mass spectra are indicative of the sequential losses of HCN units and of CH/sub 2/N/sub 2/ from adenine upon electron impact.
The reactions of native bovine catalase with superoxide and solvated electrons have been investigated using three different methods for generating these reducing substrates: [gamma]-radiolysis of oxygenated or deaerated buffer solutions in the presence of an OH radical scavenger; either xanthine or acetaldehyde with xanthine oxidase; and low-temperature (77 K) [gamma]-radiolysis of buffered ethylene glycol/water solutions with subsequent annealing of samples at 183 K. (Author).
Monolithic N-channel junction field effect transistors (NJFETs) dc characteristics, small signal parameters and noise have been studied from 300 K down to cryogenic temperatures before and after irradiation with {sup 60}Co {gamma}-rays and fast neutrons (1 MeV). Radiation induced effects on dc parameters and noise are reviewed. Noise spectral density measurements performed at various temperatures have shown that the radiation induces a noise increase which is temperature and frequency dependent. (orig.). 14 refs.
Hazardous UV-radiation and short-wavelength visible (blue) light is emitted by the high temperature plasma above the welding-keyhole. Ozone and NO_x is produced due to UV-induced photodissociation of oxygen and high temperature gas-phase reactions. Spectral measurements of the plasma emission show that the allowed dose for UV-radiation and blue light exposure per work day can be exceeded in as short as a few seconds. Similarly, measurements and models of the ozone and NO_x concentration show that the maximum workplace concentrations might be reached quickly if no appropriate exhaust and filter system is installed. (author)
Subcritical source-driven noise measurements are simultaneous Rossia and randomly pulsed neutron measurements that provide measured quantities that can be related to the subcritical neutron multiplication factor. In fact, subcritical source-driven noise measurements should be performed in lieu of Rossia measurements because of the additional information that is obtained from noise measurements such as the spectral ratio and the coherence functions. The basic understanding of source-driven noise analysis measurements can be developed from a point reactor kinetics model to demonstrate how the measured quantities relate to the subcritical neutron multiplication factor.
X-ray observations of the RSCVn system sigma Geminorum have been undertaken with the ROSAT observatory. Several spectra of very good signal-to-noise ratio were obtained. Spectral fitting using metal abundances amounting to 50% of solar values reveal two temperature components at 2 MK and 12 MK. Previous EXOSAT observations showed another component at 40 MK. Particular interest is focused on the temporal variations of the X-ray emission. It is found that variations occur on time scales ranging from years to hours and minutes.
RADSOLVER is a computer program which calculates the radiation energy transport in cavity type receivers having an arbitrary number of apertures through which collimated beams of solar radiation enter. In contrast to the common assumption of gray (or semi-gray) surfaces used in the modeling of radiation transport, RADSOLVER accounts for the wavelength-dependence of emission, absorption and reflection with a band model of the radiative properties. It is intended that this report serve both as an instruction manual for the use of the RADSOLVER code and a vehicle for presenting the underlying theory. Illustrative examples along with input and output are presented.
The paper presents results of experimental research on the interaction of a pulsed plasma-ion stream with a tungsten (W) target. The pulsed hydrogen plasma was produced within the RPI-IBIS (Multi-Rod Plasma Injector) facility at IPJ in Swierk. Measurements were carried out by means of optical spectroscopy and corpuscular diagnostic techniques. For experiments with the W-target the operational conditions (so-called PID mode) were chosen when a clean hydrogen plasma stream was generated. Attention was paid to the identification of WI and WII spectral lines.
The method of reactivity determination using noise analysis correlation measurements with /sup 252/Cf was used to determine the reactivity for subcritical 17.77-cm-dia uranium (93.2 wt percent /sup 235/U) metal cylinders with reactivities as low as 25 dollars. Far subcritical tests were performed with right circular cylinders of uranium metal for which the subcritical reactivity was known from other inverse kinetics and prompt neutron decay constant measurements.
The polarized triple-axis spectrometer TASP at SINQ has been optimized for measuring magnetic cross sections in condensed matter. The neutrons are polarized or analyzed either by means of benders or Heusler monochromators. The beam divergence, i.e. the intensity, and the spectral range of the neutrons is rather large because of the supermirror coatings of the feeding neutron guide. The intensity can be further increased at the sample position by means of a focussing monochromator and a focussing anti-trumpet. The end position of TASP allows the tailoring of the neutron beam already before the monochromator and to scatter neutrons over very wide ranges of angles. (author) 6 figs., 1 tab., 8 refs.
Arrays of CdS:Mn{sup 2+}:Cu{sup +} micro- and nanowires grown in polycarbonate ion-track templates exhibit photoluminescence in the spectral domain ranging from 500 to 800 nm at room temperature. A comparison with similar CdS and CdS:Mn{sup 2+} wire arrays is presented. The individual contributions to the emission spectra of Cu{sup +} and Mn{sup 2+} ions in the CdS matrix are explained using their energy level schemes. Also SEM, EDX and EPR data are given for these wires. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Arrays of CdS:Mn"2"+:Cu"+ micro- and nanowires grown in polycarbonate ion-track templates exhibit photoluminescence in the spectral domain ranging from 500 to 800 nm at room temperature. A comparison with similar CdS and CdS:Mn"2"+ wire arrays is presented. The individual contributions to the emission spectra of Cu"+ and Mn"2"+ ions in the CdS matrix are explained using their energy level schemes. Also SEM, EDX and EPR data are given for these wires. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Raman scattering measurements of the Esub(g) and Tsub(2g) optical phonons in V"3Si, Nb"3Sn, V"3Ge, Cr"3Si, V"3Pt, and Nb"3Pt are presented and discussed in terms of interaction with interband electronic excitations. Data on superconducting Nb"3Sn is presented and modifications to the phonon spectral function and the spectrum of Raman active interband electronic excitations in the superconducting state are discussed. (orig.).
A possible novel application of hard x-ray emitted during laser-plasma interaction was discussed. The authors established an Optical Transform Function to study the joint effect of the spectral distribution and temporal profile of the laser-produced x-ray on x-ray phase imaging. Though the laser-produced x-ray pulse duration is short and incoherent, the analysis confirms that the current x-ray phase imaging theory still holds for laser-produced x-ray phase imaging
In the inflationary scenario of loop quantum cosmology (LQC) in the presence of inverse-volume corrections, we give analytic formulas for the power spectra of scalar and tensor perturbations convenient to confront with observations. Since inverse-volume corrections can provide strong contributions to the running spectral indices, inclusion of terms higher than the second-order runnings in the power spectra is crucially important. Using the recent data of cosmic microwave background (CMB) and other cosmological experiments, we place bounds on the quantum corrections for a quadratic inflaton potential.
A hysteretic subcritical period-doubling bifurcation is observed in the nonlinear strain dynamics of a magnetostrictive oscillator. The dynamic strain response of the magnetostrictive oscillator was observed with a high-resolution fiber optic interferometer. The effects of low-frequency modulation and band-limited stochastic fluctuations on such a bifurcation are investigated. Power spectral density measurements show that for an optimal value of externally injected noise the signal-to-noise ratio of a low-frequency modulation signal is enhanced by greater than 14 dB, thus indicating the first experimental observation of stochastic resonance near a bistable period-doubling bifurcation. 10 refs., 7 figs.
The problem of search for new materials for spectrally positioned laser sources, which is central for modern photonics, is discussed. The use of the stimulated Raman scattering effect in crystals offers a highly efficient way to the design of such sources. The recent results of investigations into this effect for a large number of various types of crystalline materials are presented. The most promising compounds, as regards the realisation of different laser operation modes, are considered, including calcium, strontium, barium and lead molybdates and tungstates. Several examples of functioning efficient lasers based on novel materials exhibiting the stimulated Raman light scattering effect are given.
A new coumarin-based sensor molecule (L1) has been synthesized and this was found to bind calcium and magnesium ions more effectively as compared to other alkali/alkaline earth/lanthanide and certain transition metal ions. A significant enhancement in fluorescence intensity was observed on binding to Ca2+ and Mg2+ ions; while a minor quenching was observed for weakly bound Hg2+, Ni2+, Fe3+, and Co2+ ions. PET process, coupled with the ICT process, is proposed to explain the observed spectral response.
This work has carried out a molecular structure characterization of two Brazilian plants, Harpalyce brasiliana Benth and Bredemeyera floribunda Wild, using {sup 1} H and {sup 13} C NMR spectroscopy. NMR spectra were presented and analysed, then several structures have been proposed based on spectral data, and finally the structural determination was done 3 refs., 4 figs., 1 tab.
Magnetic fluctuations present in the paramagnetic Mn{sub 0.81}Ni{sub 0.19} system have been investigated by measuring inelastic magnetic neutron scattering from a single crystal at temperatures of 450, 585 and 700 K. Antiferromagnetic correlations are observed to be present at all the temperatures studied. The spectral width of the magnetic scattering has been observed to increase with temperature, while the spatial range of the magnetic correlations is seen to decrease as the temperature is raised. The wave-vector-dependent susceptibility is found to follow a Curie-Weiss law near the (1 0 0) position, in agreement with theoretical predictions.
To investigate the magnetic fluctuations and for further transport study, the poloidal and radial magnetic field measurement is conducted on the Sino United Spherical Tokamak (SUNIST). Auto-power spectral density indicates that the magnetic fluctuation energy mainly concentrates in the frequency region lower than 10 kHz. The magnetic field oscillations, which are characterized by harmonic frequencies of 40 kHz, are observed in the scrape-off layer; by contrast, in the plasma core, the magnetic fluctuations are of Gaussian type. The time-frequency profiles show that the poloidal magnetic fluctuations are temporally intermittent. The autocorrelation calculation indicates that the fluctuations in decorrelation time vary between the core and the edge. (authors)
An historic Strontianite-type specimen from Strontian, Scotland, UK, was characterized to broaden our knowledge on luminescence properties of common carbonates. These fibrous aggregates are Strontianite (Sr{sub x}Ca{sub 1-x}CO{sub 3}) with circa 6% of CaO, interfacial water, hydrosilicate anions and substitutional divalent cations, e.g., Ca{sup 2+}, Mn{sup 2+}, Fe{sup 2+} in structural Sr{sup 2+} positions. The specimen was analyzed by X-ray Fluorescence Spectrometry (XRF), Environmental Scanning Electron Microscopy coupled with an Energy Dispersive X-ray Spectroscopy (ESEM-EDS) probe, Spatially-resolved Cathodoluminescence under the Scanning Electron Microscope (SEM-CL), Differential-Thermal Analyses (DTA), Thermogravimetry (TG), Thermoluminescence (TL), Radioluminescence (RL) and High Resolution Spectra Thermoluminescence (3DTL), to gain an overview of the spectral emissions, the defect linkages were modified by heating from room temperature (RT) up to 500 deg. ...
Laser gain of the NIJI-IV compact storage-ring-based Free Electron Laser (FEL) system at AIST reached #approx#9% at 200 nm for an average beam current of 16.3 mA. In addition to such a drastic gain enhancement, improvement of the laser-cavity performance has led to successful FEL lasing in the vacuum ultraviolet below 200 nm even in a compact system. Temporal and spectral characteristics of the NIJI-IV FEL were examined around 200 nm. FEL performance will be briefly discussed from the application point of view.
In this project we developed photonic crystal modeling capability and fabrication technology that is scaleable to large area. An intelligent optimization code was developed to find the optimal structure for the desired spectral response. In terms of fabrication, an exhaustive survey of fabrication techniques that would meet the large area requirement was reduced to Deep X-ray Lithography (DXRL) and nano-imprint. Using DXRL, we fabricated a gold logpile photonic crystal in the <100> plane. For the nano-imprint technique, we fabricated a cubic array of gold squares. These two examples also represent two classes of metallic photonic crystal topologies, the connected network and cermet arrangement.
Spectral and energy luminescence characteristics of R6G dye solutions in ethanol with addition of Ag nanoparticle suspensions in different aggregate states are experimentally investigated. It is demonstrated that incorporation of non-aggregated and aggregated nanoparticles causes the superluminescence thresholds in R6G solutions to decrease. It is established that the optical properties of the laser beam propagation channel are transformed when low-power (20?mW) cw laser radiation passes through the suspension of nanoparticles. This is manifested through the occurrence of a region with enhanced nanoparticle density in the laser beam center, on which diffraction of laser radiation is observed.
Spectral and energy luminescence characteristics of R6G dye solutions in ethanol with addition of Ag nanoparticle suspensions in different aggregate states are experimentally investigated. It is demonstrated that incorporation of non-aggregated and aggregated nanoparticles causes the superluminescence thresholds in R6G solutions to decrease. It is established that the optical properties of the laser beam propagation channel are transformed when low-power (20 mW) cw laser radiation passes through the suspension of nanoparticles. This is manifested through the occurrence of a region with enhanced nanoparticle density in the laser beam center, on which diffraction of laser radiation is observed.
Coherent x-ray production by a seeded free electron laser (FEL) is important for next generation synchrotron light sources. The authors examine the feasibility and features of FEL emission seeded by a high-order harmonic generation (HHG) of an infrared laser. In addition to the intrinsic FEL chirp, the longitudinal profile and spectral bandwidth of the HHG seed are modified significantly by the FEL interaction well before saturation. This smears out the original attosecond pulselet structure. The authors introduce criteria for this smearing effect on the pulselet and the stretching effect on the entire pulse. They discuss the noise issue in such a seeded FEL.
Fission rate assessments are being made in FFTF to provide input for determination of power distribution, peak power, total power, fuel burnup distribution, conversion ration and neutron spectral information by the multiple foil reaction rate method. A goal of the initial FFTF Characterization Program is to measure isotopic fission rates to an accuracy of 2 to 5% throughout FFTF by radiometric techniques. To achieve this goal, measurements were made in the FFTF In-Reactor Thimble to reduce the uncertainties of key parameters needed for radiometric fission rate mapping of the FFTF core.
Several experiments showed that the classical Kolmogorov power spectral density of the refractive-index sometimes does not properly describe the statistics of the atmosphere. In this paper we show an experimental testbed able to generate non-classical Kolmogorov turbulence by using a liquid crystal spatial light modulator. The testbed is used at Naval Postgraduate School for laboratory investigation of laser beam propagation in maritime environment where a power law different from classical Kolmogorov, 11/ 3, could be present. Applications of this testbed are ship to-ship free space optical communication, imaging and high energy laser weapons.
We consider the spin-up of the white dwarf in non-magnetic cataclysmic variables (CVs) during secular evolution. If this is unresisted, CVs are quenched as boundary-layer emitters once the binary period has decreased by #approx# 1 hr. Angular momentum loss in nova explosions may, however, prevent the star reaching breakup. If the explosions remove (1 + #epsilon#) x the mass accreted between outbursts, values 0.5 < #approx# #epsilon# < #approx# 1 allow CVs to be modest boundary-layer emitters for most of their lifetimes. Spectral effects will limit their detection as soft X-ray sources. (author).
The half-metallic Heusler alloy Ni{sub 2}MnIn is of high interest for use in spin electronics since at the Ni{sub 2}MnIn/InAs interface a spin polarization of 100% is predicted. We prepare high-quality thin films of 20-60nm thickness by co-evaporation and DC magnetron sputtering. Point-contact Andreev reflection spectroscopy yields a spin polarization of up to 54%. By spectral generalized magneto-optical ellipsometry, the dielectric and magneto-optical properties are determined and ferromagnetic behavior below the Curie temperature T{sub C}=318K is proved.
The authors have developed a complex of activation methods of analysis using a nuclear reactor (nuclear activation analysis) and a cyclotron (charged-particle activation analysis). The methods have been used to determine the concentrations of more than 20 elements in five medicinal plants native to Uzbekistan: Syrian rue (Peganum harmala L.), plantain (Plantago lanceolata), peppermint (Mentha piperata L.), sage (Salvia officinalis L.), and ziziphora (Ziziphora bungeana Yur.). The results of radio-activation analysis were compared with the results of standard spectral analysis performed in another laboratory and the accuracy of the procedures developed was evaluated on the basis of the results.
This paper describes the chemical constituents isolated from aerial parts of the plant Galianthe brasiliensis. From a methanol extract, the iridoid glycosides asperuloside, deacetylasperuloside, mixture of Z- and E-6-O-p-coumaroylscandoside methyl ester, the triterpene ursolic acid and the steroids stigmasterol, campesterol, b-sitosterol and 3-O-b-glucopyranosyl sitosterol were isolated. The structures of the natural products were identified on the basis of spectral data, including 2D NMR experiments. The antiproliferative properties of the crude methanolic extract were investigated against a series of nine human cancer cell lines. (author)
To get a better understanding of the condensation oscillation and chugging process during blowdown of a BWR after a LOCA a large number of large scale pressure suppression experiments have been performed in several countries. ECN has performed a detailed analysis of the results of one of these experiments, e.g. the DAS M10 experiment of GKSS. This analysis includes the following aspects: Power Spectral Density (PSD) analysis of the data, analysis of the acoustic frequencies of the downcomers and an analysis of the eigenfrequencies of the downcomers. The results of these analyses and an evaluation are given in this paper. It is shown that all dominant frequencies in the experimental results can be correlated with the vent-acoustic or eigenfrequencies. (orig.).
This paper presents an analysis of the performance of a selective emitter using small particles of rare earth compounds stable at high temperatures in a low emittance inert gas stream. An expression for the spectral emissive power excluding radiation scattering was derived to include the radiation in the emission band, produced by electronic transitions of the rare earth ion, and the continuum radiation outside the emission band produced by the rare earth host. Preliminary results suggest that a selective emitter based on suspended rare earth oxide particles will have high efficiency and merits further experimental investigation. {copyright} {ital 1996 American Institute of Physics.}
Spectral appearance and concentrations of the most prominent metabolites are affected by brain development. This knowledge is essential for the detection of pathological changes in pediatric patients. This paper discusses specific conditions of MR spectroscopic examination of children and the effects of age on MR spectra quality and quantitation of the studied metabolites. Clinical examples show several diseases that are reflected in changes in "1H MR spectra due to pathological alterations in the biochemical pathways of the observed metabolites. Attention is given to the main metabolites such as N-acetylaspartate, creatine/phosphocreatine, cholines, lactate, inositol, etc.
Spectral absorption properties of total suspended matter (TSM) and colored dissolved organic matter (CDOM) are important for the use of the bio-optical model to estimate water quality parameters. This study aims to investigate the variation in the absorption coefficients of TSM and CDOM of inland waters. A total of 92 water samples were collected from Shitoukoumen Reservoir and Songhua Lake in Northeast China, analyzed for TSM and Chl-a, and measured for the absorption coefficient of TSM, CDOM and total pigments using a laboratory spectrophotometer. The absorption coefficient of TSM has been decomposed for phytoplankton and inorganic sediments. The results show that for Shitoukoumen Reservoir, CDOM has strong absorptions with shallow absorption slopes (i.e., the coefficient S in a(?)=a(?0)exp[-S(?- ?0)]) and large absorption at 355 nm; and for Songhua Lake, CDOM follows similar spectral absorption curves but less variation in the S value. The ...
We present observations of PSRs J0437-4715, J0738-4042, J0835-4510, J0908-4913, J1048-5832, J1622-4950, J1644-4559, J1721-3532 and J1740-3015 at 17 GHz using the Parkes radio telescope. All nine were detected at 17 GHz, additionally, we detected PSR J0835-4510 and J1622-4950 at 24 GHz. Polarization profiles of each pulsar and the variation with frequency are discussed. In general, we find that the highly polarized edge components of young pulsars continue to dominate their profiles at 17 GHz. Older pulsars (?105 yr) appear to be almost completely depolarized. Our detection of PSR J0437-4715 is the highest frequency observation of a millisecond pulsar to date, and implies a luminosity at 17 GHz of 14 ?Jy kpc2, and a mean spectral index of 2.2. We find that the spectral index of the magnetar PSR J1622-4950 is flat between 1.4 and 24 GHz, similar to the other known radio magnetars XTE J1810-197 and 1E 1547.0-5408. The profile is similar to that ...