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Abstract Electronic structures of two representative zigzag and armchair models of aluminum phosphide nanotube (AlPNT) were investigated by density functional theory calculations. The structures were optimized and the bond lengths, tip diameters, band gaps, and dipole moments were calculated. Moreover, the quadrupole coupling constants (CQ) were calculated for the Al-27 atoms of the optimized structures. The same values of AlP bond lengths were calculated for both models. The larger value of band gap of armchair model than the zigzag model indicated the stronger dielectric property for the former model. The values of CQ(27Al) were the largest for the Al atoms placed at the tips of both zigzag and armchair AlPNT than other Al atoms, which could reveal dominant role of the Al atoms placed at...

International Nuclear Information System (INIS)

We report the results of a theoretical study of the electronic and structural properties of the hexagonal beryllium nitride, using first principle pseudopotential plane wave (PP-PW) as well as full potential linearized augmented plane wave (FP-LAPW) methods within density functional theory. In the case of PP-PW we generated the pseudopotential by the highly optimized Q_c-tuning method and used the local density approximation and generalized gradient approximation (GGA) for the exchange-correlation potential. We applied pressure on the unit cell by the Wentzcovitch and traditional methods. In the FP-LAPW approach only the GGA was used for the exchange-correlation potential. Our calculated values for structural properties, based on both approaches are in reasonable agreement with experimental and other theoretical (Hartree Fock) results. By applying the above two approaches and also the Tight Binding Linear Muffin Thin Orbital method, the ground state Kohn-Sham ...

International Nuclear Information System (INIS)

The structural, electronic and optical properties of ZnX and CdX (X = Se, Te and S) are studied using density functional theory by the Wien2k package. The energy band gap, real and imaginary parts of the dielectric function, energy loss function, optical absorption coefficient and reflectivity spectra of these compounds are calculated. The Engel-Vosko approach improves the energy band gaps of ZnX and CdX compounds. The calculated optical parameters are in good agreement with available experimental results, particularly in the Engel-Vosko approach. Furthermore the effect of hydrostatic pressure on the energy band gap, the real and imaginary parts of the dielectric function of these compounds is studied. The first and second order pressure coefficient for the energy band gaps, the static dielectric function and the static ...

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We present a comparative study on the acoustic tunneling through artificial periodical composites, from phononic crystals to acoustic metamaterials. We find that the features of the acoustic tunneling are closely related with the origins of band gaps. In particular, the band gap associated with the negative effective material parameter in the metamaterial results in a better analog of the tunneling effect to the quantum system.

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The dispersion curves E(k-bar) have been calculated for bound and resonant (110) surface states of AlSb, AlAs, and AlP. AlSb is predicted to have no surface states within the bulk fundamental band gap, but AlAs and AlP are predicted to have surface state band minima which are very near the conduction band edge, and could lie either within the gap or immediately above the edge.

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X-ray photoemission spectroscopy has been used to measure the valence band offset {Delta}E{sub v} for the AlP/GaP (001) heterojunction interface. The heterojunction samples were prepared by molecular-beam epitaxy. A value of {triangle}E{sub v}=0.43 eV is obtained (staggered band alignment, with AlP valence band below that of GaP). 24 refs., 8 figs., 1 tab.

British Library Electronic Table of Contents (United Kingdom)

The pentenary compound semiconductor Cu(In,Ga)(Se,S)2 is one of the most attractive materials for high-efficiency solar cells due to its tunable band gap to match well the solar spectrum. In this study, semiconducting Cu(In,Ga)(Se,S)2 thin films were prepared by a classical two-step growth process, which involves the selenization and/or sulfurization of In/Cu?Ga precursor. During the precursor formation step metallic In/Cu?Ga alloys were deposited onto the Mo-coated soda-lime glass substrates by DC magnetron sputter process. The respective precursors were subsequently reacted with H2Se and/or H2S gasses, at elevated temperatures. By optimizing the selenization parameters, such as the gas concentrations, reaction time, reaction temperature, and the flow of H2Se and H2S, high quality, single...

International Nuclear Information System (INIS)

The dependence of the photoluminescent properties of In_0_._4_8(Al_yGa_1_-_y)_0_._5_2P alloys (0#<=#y#<=#0.5) on growth temperature and substrate misorientation off GaAs(100) has been studied. Samples were grown using low-pressure metalorganic vapor phase epitaxy. By studying the dependence of ordering behavior in InGaP as a function of substrate misorientation and growth temperature simultaneously, a very large range in low-temperature photoluminescence emission energy---135 meV---has been obtained. The photoluminescence linewidth exhibits a strong, continuous dependence on the extent of atomic ordering (the emission energy) in the alloys. The results indicate that inhomogeneity in the microstructure of the material (i.e., between ''ordered'' domains and the ''disordered'' matrix) is the dominant photoluminescence broadening mechanism. This investigation has allowed a significant optimization of the optical properties of these materials, including the ...

Science.gov (United States)

Beta silicon carbide is an excellent candidate semiconductor material for demanding applications in high power and high temperature electronic devices due to its high breakdown voltage, relatively large band gap, high thermal conductivity and high melting...

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The pressure dependence of the photoluminescence (PL) transition associated with the fundamental band gap of ZnO nanowires has been studied at pressures up to 15 GPa. ZnO nanowires are found to have a higher structural phase transition pressure around 12 GPa as compared to 9.0 GPa for bulk ZnO. The pressure-induced energy shift of the near band-edge luminescence emission yields a linear pressure coefficient of 29.6 meV/GPa with a small sublinear term of -0.43 meV/GPa{sup 2}. An effective hydrostatic deformation potential -3.97 eV for the direct band gap of the ZnO nanowires is derived from the result.

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Ab initio calculations of the electronic structure were performed for the silver palladium oxide, Ag_2PdO_2, by the full potential mixed linearized augmented plane wave and augmented plane wave plus local orbitals method (mixed LAPW/APW+lo) within the density functional theory and using the generalized gradient approximation (GGA96, Phys. Rev. Lett. 77 (1996) 3865) for the exchange-correlation potential. The lattice parameters were calculated from the ground-state total energy versus volume curve, and are in good agreement with the available experimental results. Our calculations of band structure predicted that the compound Ag_2PdO_2 has indirect band gap, and the Pd 4d states strongly hybridize with the O 2p states all over the valence bands and conduction bands. The valence bands are composed mainly of Ag, Pd 4d states and O 2p states, while the conduction ...

International Nuclear Information System (INIS)

We studied the influence of alloying on the structural and electronic properties of the unrelaxed and relaxed Si_1_-_yC_y random alloys by means of ab initio theoretical calculations using two methods: (i) a supercell approach in connection with the plane-wave pseudopotential method; (ii) the full-potential augmented plane-wave plus local orbitals (APW+lo) method. The first method is used to obtain the relaxed atomic structure. The relaxed atomic positions obtained by pseudopotential calculations were used to calculate the band structure via the second method. The local density approximation was used for the exchange and correlation energy density functional. We investigated the lattice parameters and band gap energies. We found that a quite smaller gap appears in the neighborhood of y=0.03125 concentration of C atoms. The band gap shows a large anomalous bowing ...

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The theoretical performance of ideal single- and multijunction cells are compared at 100xconcentration under a range of cloudless-sky conditions. The sensitivities of device performance to cell temperature and spectral variations are shown to depend on the number of junctions (one, two or three), the way in which the junctions are connected (series, parallel or independent), and the band gaps of the devices. The average performances of all of the multijunction devices surpass that of a single-junction GaAs device, but the inconsistency in performance of some of the multijunction devices is significant for large variations in cell temperature and incident spectrum. The choice of band gap and connection scheme is more important than the number of junctions in determining the consistency of device performance. (orig.).

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A new band gap profile (exponential profile) for the active layer of the a-SiGe:H single junction cell has been designed and experimentally demonstrated. In this paper we compare its optical and electrical characteristics with the two more common profiles: the U- and V-shapes. As predicted by the simulations, the new profile combines the advantages of both profiles. Like the V-shape, the exponential shape reduces the amount of Ge in the i-layer, decreasing both the space charge defect density inside the i-layer and the recombination losses. It also improves the electric field. At the same time, the exponential shape generates the same current density as the U-shape.

CERN Document Server

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 ...

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We give a theoretical design for a locally resonant two-dimensional cylindrical structure involving a pair of C-shaped voids in an elastic medium which we term as double 'C' resonators (DCRs) and imbedded thin stiff bars, that displays the negative refraction effect in the low frequency regime. DCRs are responsible for a low frequency band gap which hybridizes with a tiny gap associated with the presence of the thin bars. Using an asymptotic analysis, typical working frequencies are given in closed form: DCRs behave as Helmholtz resonators modeled by masses connected to clamped walls by springs on either side, while thin bars behave as a periodic bi-atomic chain of masses connected by springs. The discrete models give an accurate description of the location and width of the stop band in the case of the DCR and the first two dispersion bands for the periodic thin ...

Science.gov (United States)

Spontaneous emission in photonic crystals with anisotropic three-dimensional dispersion relation is studied. If the upper level is below a characteristic frequency omega(1), or above omega(2), or between omega(1) and omega(2), the radiation is a localized field with a frequency in the band gap, or a propagating field with a frquency in the band, or a diffusion field, respectively. An analytical expression for the Lamb shift is obtained. The Lamb shift for the current case is small compared to that in an ordinary vacuum or in one- or two-dimensional photonic crystals due to lower density of states. PMID:11017227

Science.gov (United States)

The dependence of the photoluminescent properties of In{sub 0.48}(Al{sub {ital y}}Ga{sub 1{minus}{ital y}}){sub 0.52}P alloys (0{le}{ital y}{le}0.5) on growth temperature and substrate misorientation off GaAs(100) has been studied. Samples were grown using low-pressure metalorganic vapor phase epitaxy. By studying the dependence of ordering behavior in InGaP as a function of substrate misorientation and growth temperature simultaneously, a very large range in low-temperature photoluminescence emission energy---135 meV---has been obtained. The photoluminescence linewidth exhibits a strong, continuous dependence on the extent of atomic ordering (the emission energy) in the alloys. The results indicate that inhomogeneity in the microstructure of the material (i.e., between ordered'' domains and the disordered'' matrix) is the dominant photoluminescence broadening mechanism. This investigation has allowed a significant ...

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In this work, {beta}-SnS{sub 2} thin films have been prepared on glass substrates by the spray pyrolysis technique using an alcohol solution which contains tin chloride (SnCl{sub 4}) and thiourea (SC(NH{sub 2}){sub 2}) as precursors. The structural study shows that {beta}-SnS{sub 2} thin film prepared using optimal experimental conditions: substrate temperature T{sub s} = 280 deg. C and the concentration ratio of sulfur and tin elements in the spray solution x = [S]/[Sn] = 2.5, crystallizes in the hexagonal phase with a strong (0 0 1) X-ray diffraction line. In the same way, microprobe analyses (EPMA) as well as X-ray photoelectron spectroscopy (XPS) show the presence of undiserable phase of SnO{sub 2}. From the transmission and reflectance spectra, the band gap energy is 2.65 eV. On the other hand, the photothermal properties of such films have been studied, the thermal conductivity was K{sub c} = 0.85 W m{sup -1} K{sup ...

International Nuclear Information System (INIS)

Full text: Hybrid functionals, containing a fraction of the exact exchange, allow for a rather accurate treatment of e.g. small molecules and band gaps in bulk materials. A plane-wave based algorithm was implemented in VASP (Vienna Ab-initio Simulation Package) to accomplish the calculation of the exact exchange. Two functionals including exact exchange are presently available, i.e. the PBE0 (Perdew-BurKEX-Ernzerhof) and the HSE (Heyd-Scuseria-Ernzerhof). A rigorous assessment of the implementation was performed by geometry optimization and calculation of the atomization energies of the G2-1 quantum chemical test set, containing 55 molecules. Excellent agreement compared to corresponding Gaussian 03 data and good agreement with experiment was achieved. The mean absolute error (theory related to experiment) for the atomization energies calculated with the PBE and the PBE0 is 8.6 and 3.7 kcal/mol, respectively. To investigate ...

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The authors investigate the breakdown luminescence spectra in reverse-biased p-n heterojunctions based on gallium and aluminum phosphides and arsenides for the purpose of determining their behavior as lasing and photodetection materials. Data are given on temperature coefficients, band gap structure, bremsstrahlung, hot carrier mobility and photon emission, and transition and recombination parameters.

International Nuclear Information System (INIS)

Accurate full-potential self-consistent linearized augmented-plane-wave (FLAPW) calculations have been carried out for hexagonal boron nitride. The resulting energy-band structure indicates that this material is an indirect-gap insulator and shows the existence of two unoccupied interlayer bands, similar to those found in graphite and graphite intercalation compounds. Chemical bonding is mainly covalent, with a small charge transfer towards the nitrogen atoms. Moreover, model-potential calculations, based on first-principles FLAPW wave functions and potentials, have been used to study slabs of thickness up to 35 layers. Contrary to the case of graphite, our results do not provide evidence of surface states associated with the interlayer bands.

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The credibility of the model proposed by Ghosh in predicting the refractive indices of mixed semiconductor crystals of technological importance within their miscibility range as a function of band gap is demonstrated. The high-frequency refractive indices of four quaternary alloys Al_xGa_1_-_x_-_yIn_yP (y = 0.49, 0 #<=# x #<=# 0.51), InSb_xAs_1_-_x_-_yP_y (y = 2.2x, 0 #<=# x #<=# 0.313, 0 #<=# y #<=# 0.638), Cd_xZn_1_-_x_-_yHg_ySe (x + y = 1, 0.153 #<=# x #<=# 0.684, 0.316 #<=# y #<=# 0.847), and CdS_1_-_x_-_ySe_xTe_y (x + y = 1, 0.15 #<=# x #<=# 0.93, 0.07 #<=# y #<=# 0.85) are calculated according to the relation n"2-1 = A/(E_g + B)"2 where A is an energy gap dependent constant and B is a constant depending on crystal ionicity. The calculated values show excellent agreement with the experimental data thus justifying the validity of the model.

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We studied the effects of co-doping with Li and Al on the energy gaps of MgB2 by performing point-contact Andreev-reflection spectroscopy (PCAR) in polycrystalline Mg1-x(Al?Li1-?)xB2 samples with x?0.4. Even though the lattice parameters and the critical temperature of the compound simply scale with the effective Al content ?x, irrespective of the Li concentration, the energy gaps do not. In particular, for a given effective Al content, the comparison with Mg1-y(Al)yB2 with y = ?x shows that the ? bandgap is practically the same while the ? bandgap is higher. A clear gap merging is observed in the most doped sample (x = 0.4) when Tc<20 K. The results are discussed within the two-band Eliashberg theory and compared to the outcomes of first-principles calculations of the effects of Li and Al co-doping on the electronic structure of magnesium diboride.

British Library Electronic Table of Contents (United Kingdom)

The microdynamics of soliton waves and localized modes of nonlinear vibrations of the acoustic and optical types in uranium nitride has been investigated. It has been shown that, with an increase in the excitation energy in the spectral gap between the bands of optical and acoustic phonons, the energies of solitons increase, whereas the energies of local modes decrease. The previously experimentally observed unidentified quasi-resonant features, which shift in the gap with variations in the temperature, can represent the revealed soliton waves and local modes. The microdynamics of heat conduction of uranium nitride has been studied for the stochastic generation of soliton waves and local modes in the case of spatially distant energy absorption. The thermal conductivity coefficient determin...

International Nuclear Information System (INIS)

The electronic structure and optical properties in tetragonal ceramics PbTiO_3, are studied by using full-potential linearized augmented plane wave method in density functional theory with the generalized gradient approximation by WIEN2K package. The theoretical calculated optical properties and energy loss spectrum yield a static refractive index of 2.59 and a plasmon energy of 22.7eV for the tetragonal phase. The effective electron number at low energy saturates near 22-23eV with the value of 50 for the effective electron number. The results show a indirect band gap of 2.2eV at the I' point in the Brillouin zone. The :calculated band structure and density of states of PbTiO_3 agree with previous experimental and theoretical results.

CERN Document Server

We point out that electromagnetic one-way edge modes analogous to quantum Hall edge states, originally predicted by Raghu and Haldane in 2D gyroelectric photonic crystals possessing Dirac point-derived bandgaps, can appear in more general settings. In particular, we show that the TM modes in a gyromagnetic photonic crystal can be formally mapped to electronic wavefunctions in a periodic electromagnetic field, so that the only requirement for the existence of one-way edge modes is that the Chern number for all bands below a gap is non-zero. In a square-lattice gyromagnetic Yttrium-Iron-Garnet photonic crystal operating at microwave frequencies, which lacks Dirac points, time-reversal breaking is strong enough that the effect should be easily observable. For realistic material parameters, the edge modes occupy a 10% band gap. Numerical simulations of a one-way waveguide incorporating this crystal show ...

Science.gov (United States)

Efficient, low-temperature conversion of infrared light into visible light (red, orange, green) is reported at single heterojunctions and undoped quantum wells of GaAs and ordered Al{sub {ital x}}Ga{sub 1{minus}{ital x}}InP{sub 2}; an increase in photon energy of 700 meV is obtained. The signal originates from the high-band-gap layers and disappears only if the excitation energy is tuned below the GaAs band gap. The intensity of the up-converted photoluminescence (PL) is found to decrease significantly slower with increasing temperature than that of the regular PL and it remains observable up to 200 K. Interface-induced cold Auger processes along with the presence of trapped states for both electrons and holes in these ordered alloys account for this nonlinear mechanism. A colinear double-beam experiment confirms this. {copyright} {ital 1996 The American Physical Society.}

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The near normal incidence reflectivity of the ferromagnets U"3P"4 and U"3As"4 and the isostructural but diamagnetic compounds Th"3P"4 and Th"3As"4 has been measured from 0.03 to 12 eV. Trithorium tetraphosphide and tetraarsenide are shown to be indirect gap semiconductors with gap energies of 0.43 and 0.39 eV, respectively. U"3P"4 and U"3As"4 display similar sets of p#->#d transitions than the corresponding thorium compounds, however, they are shifted by 0.85 eV to lower photon energies. It is concluded that the uranium compounds are metals due to a merging of the valence p band into the 6d conduction band giving direct experimental evidence for a p-f mixing effect of the same size. Energy level schemes are derived. (author).

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The influence of small amounts of alloying elements (0.36% Cu and 0.47% Cr) on the semiconducting properties of passive films formed on weathering steels was investigated either in tetraborate/boric acid buffer solution (pH 9.2) or artificial atmospheric environment (SO_2-containing environment). The electrochemical behaviour was assessed by potentiodynamic polarisation, capacitance measurements and photoelectrochemistry. The chemical characterisation of the films was carried by Auger electron spectroscopy. The polarization results obtained in the buffer solution show that the addition of chromium decreases the passive current density. The capacitance results show that the films behave as an n-type semiconductor with shallow and deep donor levels situated in the forbidden gap. The presence of copper seems to affect the density of the shallow and of the deep donor levels in the forbidden gap, and as chromium, it also decreases the doping density ...

British Library Electronic Table of Contents (United Kingdom)

A mechanical model with local resonators is proposed as an acoustic metamaterial that exhibits an unusual frequency-dependent effective stiffness. If treated as an equivalent elastic solid, its effective Young's modulus can become unbounded or vanishingly small at two respective frequencies. Moreover, in a certain frequency range, the effective Young's modulus would become negative, resulting in a band gap that coincides with this frequency range. The wave attenuation behavior and mechanism are studied through numerical simulations on the acoustic metamaterial model. The capability of the metamaterial to selectively block or filter unwanted waves is demonstrated by a numerical simulation example.

CERN Document Server

A recurrent idea in the study of complex systems is that optimal information processing is to be found near bifurcation points or phase transitions. However, this heuristic hypothesis has few (if any) concrete realizations where a standard and biologically relevant quantity is optimized at criticality. Here we give a clear example of such a phenomenon: a network of excitable elements has its sensitivity and dynamic range maximized at the critical point of a non-equilibrium phase transition. Our results are compatible with the essential role of gap junctions in olfactory glomeruli and retinal ganglionar cell output. Synchronization and global oscillations also appear in the network dynamics. We propose that the main functional role of electrical coupling is to provide an enhancement of dynamic range, therefore allowing the coding of information spanning several orders of magnitude. The mechanism could provide a microscopic ...

CERN Document Server

The work identifies the first lattice decoding solution that achieves, in the general outage-limited MIMO setting and in the high-rate and high-SNR limit, both a vanishing gap to the error-performance of the (DMT optimal) exact solution of preprocessed lattice decoding, as well as a computational complexity that is subexponential in the number of codeword bits. The proposed solution employs lattice reduction (LR)-aided regularized (lattice) sphere decoding and proper timeout policies. These performance and complexity guarantees hold for most MIMO scenarios, all reasonable fading statistics, all channel dimensions and all full-rate lattice codes. In sharp contrast to the above manageable complexity, the complexity of other standard preprocessed lattice decoding solutions is shown here to be extremely high. Specifically the work is first to quantify the complexity of these lattice (sphere) decoding solutions and to prove the surprising result ...

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By using a model dielectric matrix in electron self-energy evaluations the computational effort of a quasiparticle band-structure calculation for a semiconductor is greatly reduced. Applications to various systems with or without inversion symmetry, having narrow or wide band gaps, and semiconductor alloys demonstrate the reliability and accuracy of the method. Calculations have been performed for thirteen semiconducting or insulating materials: Si, LiCl, AlP, AlAs, AlSb, GaP, GaAs, GaSb, InP, InAs, InSb, and the Al_0_._5Ga_0_._5As and In_0_._5_3Ga_0_._4_7As alloys. Excellent agreement with experimental results is obtained for the quasiparticle energies for these materials. The only three exceptions, E(#GAMMA#_1_c) of AlP, E(L_1_c) of AlAs, and E(L_1_c) of AlSb are discussed and attributed to various experimental uncertainties. Several other quasiparticle-excitation-related properties are also examined ...

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This paper presents a new approach for solving multistage decision problems in power system operation by using a new fuzzy dynamic programming technique. To investigate its validity, the hydrothermal scheduling problem is used as an example problem. Within this problem, uncertainty elements exist such as load demand and natural hydraulic inflows to reservoirs exist which can be expressed by fuzzy numbers. Two new fuzzy decision making techniques for selecting the optimal operating states at each stage are introduced. Further, the hydrothermal scheduling solution obtained had an operating band defined by upper and lower bounds. To further enhance the information that this operating band provides, a midpoint operation technique that applies both forward and backward fuzzy DP is also introduced. This allows the system operator to consider current operating conditions to determine a suitable stage by stage operation policy ...

CERN Document Server

Many sunspot cycles are double peaked. In 1967 Gnevyshev suggested that actually all cycles have two peaks generated by different physical mechanisms, but sometimes the gap between them is too short for the maxima to be distinguished in indices of the total sunspot activity. Here we show that indeed all cycles have two peaks easily identified in sunspot activity in different latitudinal bands. We study the double peaks in the last 12 sunspot cycles and show that they are manifestation of the two surges of toroidal field - the one generated from the poloidal field advected all the way on the surface to the poles, down to the tachocline and equatorward to sunspot latitudes, and another one generated from the poloidal field diffused at midlatitudes from the surface to the tachocline and transformed there into toroidal field. The existence of these two surges of toroidal field is due to the relative magnitudes of the speed of the large-scale solar ...

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We investigated phase transition of ilmenite-type AgSbO3 to pyrochlore by post-heat treatment and the synergy effect of the mixed phases of AgSbO3 on the photocatalytic activities to enhance the activities. The AgSbO3 with an ilmenite structure was prepared by a cation-exchange method. Phase transition from the ilmenite to pyrochlore occurred by proper control of post-heat treatment. The sample that was obtained by post-heat treatment of ilmenite-type AgSbO3 at 660^oC for 3h consisted of both of the ilmenite and pyrochlore phases, and the sample at 685^oC for 4h mainly consisted of the pyrochlore phase. Together with an increase in the ratio of the pyrochlore phase, the optical absorption spectra blue-shifted. The band gaps of single phases of the ilmenite and the pyrochlore were 2.4 and 2...

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The passive films formed on 316L stainless steel in various NaCl solutions have been investigated by capacitance measurements (Mott-Schottky). Pitting parameters have been determined using the galvano-kinetic polarisation method. The obtained results reveal the existence of a shallow and a deep donor level localised in the band gap of the semiconducting oxide film. These energy levels are due to iron ions in the tetrahedral and octahedral positions. It also appears that the participation of the deep donor level effects the electric field. The study developed allows us to compare characteristic parameters of the electronic structure of the passive film to those related to pitting susceptibility. (authors) 25 refs.

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Abstract High-crystallinity hierarchical anatase TiO2 hollow spheres were prepared by a high-temperature (350 C) and non-aqueous solvothermal method in the absence of water, templates, or additives. The hollow structures were assembled from highly crystallized TiO2 nanoparticles and exhibit superior photocatalytic properties relative to those of Degussa P25 TiO2 under irradiation with UV light. The influence of reaction temperature on the crystallinity, morphology, crystallite shape and size, band gap, specific surface area, and pore size distribution of TiO2 has been studied in detail. It is evident that reaction temperature is the most important factor to increase the crystallinity of TiO2 in order to improve its charge transfer and transport properties, which are important in photocatal...

British Library Electronic Table of Contents (United Kingdom)

A two-dimensional (2D) lattice model with anisotropic resonant microstructures is found to provide an anisotropic band gap structure. A 2D continuum with anisotropic effective mass density is introduced to represent this lattice system. Two methods are proposed to derive the equivalent continuum. In the first method, the effective mass density of the equivalent continuum is obtained by matching the dispersion relations for harmonic waves propagating in the principal directions. The second approach employs an approximate estimation of the effective mass density by volume-averaging an effective mass that represents the resonant microstructure. For both equivalent continuum models, the effective mass density is frequency-dependent and may become negative in certain frequency ranges. Subsequen...

Science.gov (United States)

The authors have studied (Al{sub x}Ga{sub 1{minus}x}){sub 0.5}In{sub 0.5}P doped with tellurium using deep level transient spectroscopy and associated electrical measurements. Several defect states are observed in the upper half of the band gap, that are believed to be intrinsic to the alloy system as well as related to the tellurium donors. Defects observed at measurement temperatures above 390 K exhibit a hysteretic behavior. The observed spectra depend on the biasing conditions applied to the Schottky diode during cooling. The hysteretic behavior suggests the existence of different defect configurations, which can be accessed under conditions of high temperatures and electrical stress, but remain stable below 300 K.

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The low-power operation of a semiconductor buried-heterostructure Raman laser is reported. We are developing these devices for very wide-band optical communication in the terahertz frequency region. It has a structure with a GaP active layer and Al{sub {ital x}}Ga{sub 1{minus}{ital x}}P cladding layers, which are grown by the temperature-difference method under controlled vapor pressure. By making the stripe width 30--40 {mu}m, we have obtained a threshold pump power of 500 mW. A low-threshold semiconductor Raman laser can be pumped by semiconductor injection lasers. We have measured the optical loss of the waveguide and detected the contribution from scattering and leakage at heterointerfaces.

International Nuclear Information System (INIS)

In this work we study the structural and electronic properties of Be chalcogenides (BeS, BeSe and BeTe) using two different methods: the full-potential linear augmented-plane wave (FP-LAPW) and the plane-wave pseudopotential (PPsPW). The exchange-correlation effects are treated in the local-density approximation (LDA) and the generalized-gradient approximation (GGA). We have evaluated the ground-state quantities such as equilibrium volume, bulk modulus and its pressure derivative as well as the elastic constants. Various structural phase transitions were considered here in order to confirm the most stable structure and to predict the phase transition under hydrostatic pressure. In addition we have studied the band structure and the density of states, which show a wide indirect band gap for these compounds. These results were in favourable agreement with previous theoretical works and the existing experimental data. To ...

International Nuclear Information System (INIS)

In this paper, a time-domain equivalent circuit method is applied to solve dispersion of coupled-cavity travelling-wave tube (CCTWT). First, the time-domain circuit equations of CCTWT coupled-cavity chain are deduced from the equivalent circuit model. Then, the equations are solved numerically by fourth-order Runge-Kutta method and a program CTTDCP is developed using MATLAB. Last, a L-band CCTWT is calculated using CTTDCP and the cavity pass-band of this tube is computed to be 1.08-1.48 GHz, which is consistent with the experimental results and the simulation results of electromagnetic code and demonstrates the validity of the time-domain equivalent circuit method. In addition, a new design method which uses the equivalent circuit method and electromagnetic simulation together to optimize the cold cavity characteristics of CCTWT is proposed. (authors)

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Novel CdS hollow microspheres have been successfully synthesized via a facile template-free solution-phase reaction from cadmium nitrate and thioacetamide precursors. The morphology of CdS hollow microspheres depends strongly on the ratio between the precursors, cadmium nitrate to thioacetamide ratio. The physical properties of the hollow microspheres have systematically been studied by different characterization methods. The stoichiometry of the hollow microspheres studied by the energy dispersive X-ray diffraction spectroscopy confirmed that the synthesized CdS hollow microspheres are nearly stoichiometric bulk like CdS. The morphology of the hollow microspheres studied by high resolution scanning electron microscopy and transmission electron microscopy observations showed that the CdS hollow microspheres of the size of 2.5 ?m have hollow structure and are constructed by several nanoparticles of the size between 30 and 40 nm. The UV-visible diffuse reflectance spectroscopy studies ...

International Nuclear Information System (INIS)

We present results from the first studies of electric-field effects on optical transitions in visible-band-gap InGaP/InAlGaP multiple-quantum-well (MQW) structures. These structures, grown at 775 degree C by metalorganic vapor phase epitaxy on (100) GaAs substrates misoriented 6 degree towards P(111)right-angle left-angle 111 right-angle A, consist of nominally undoped MQWs surrounded by doped In_0_._4_9Al_0_._5_1P cladding layers to form p-i-n diodes. The Stark shifts of various allowed and forbidden quantum-well transitions were observed in bias-dependent electroreflectance spectra of In_0_._4_9Ga_0_._5_1P/In_0_._4_9(Al_0_._5Ga_0_._5)_0_._5_1P MQW samples with 10-nm-thick layers. We find the magnitude of these shifts to depend on the details of the Mg doping profile, confirming the importance of Mg diffusion and unintentional background doping in these materials. Our results show that (InAlGa)P materials are promising for visible-wavelength electro-optic ...

International Nuclear Information System (INIS)

The cross-coupled interferometer is a new design for interferometric gravitational wave detectors. Similar to the baseline gravitational wave detectors proposed for Advanced LIGO, it uses long-arm cavities in which the signal is generated. The signal fields are then extracted from the arm cavities with an additional cavity behind the long-arm cavities. The tuning of this signal extraction cavity and the parallel tuning of the signal recycling mirror can be used to optimize the peak frequency and the bandwidth of the detector independently. If we replace the signal recycling mirror by a small cavity, it is possible to amplify signals in two different frequency bands.

Energy Technology Data Exchange (ETDEWEB)

In this work, we describe the fabrication and operating characteristics of GaAs/AlGaAs thin film solar cells processed by the epitaxial liftoff (ELO) technique. This technique allows the transfer of these cells onto glass substrates. The performance of the lifted-off solar cell is demonstrated by means of electrical measurements under both dark and illuminated conditions. We have also optimized the light trapping conditions in this direct-gap material. The results show that good solar absorption is possible in active layers as thin as 0.32 {mu}m. In such a thin solar cell, the open circuit voltage would be enhanced. We believe that the combination of an epitaxial liftoff thin GaAs film, and nano-texturing can lead to record breaking performance. {copyright} {ital 1997 American Institute of Physics.}

International Nuclear Information System (INIS)

A new study on the pressure-induced phase transitions of TiO_2 has been performed using all-electron density-functional theory based computations with the projector augmented wave and the linearized augmented plane wave methods considering five experimentally observed structures. The static results yield a picture that is consistent with experiments, i.e., phase transitions with pressure are predicted as rutile #-># monoclinic baddeleyite (MI) #-># orthorhombic I (OI) #-># cotunnite (OII) on compression, and OII #-># OI #-># MI #-># columbite (TiO_2II) on decompression. The elasticities of these five polymorphs are compared. Except for the baddeleyite structure, which is considerably softer than the other polymorphs, all phases show a zero pressure bulk modulus in the range of 200-240 GPa, consistent with compression results and the single crystal elastic constant; on the basis of these results we can say that the cotunnite phase is not a superhard TiO_2 polymorph as ...

Energy Technology Data Exchange (ETDEWEB)

Polycrystalline ZnS semiconducting films have been prepared in sandwich configuration by spray pyrolysis technique using ZnO-coated glass substrates and mixed aqueous solutions of ZnCl{sub 2} and thiourea. The sandwich structures have been produced successfully by means of ZnO-coated glass substrates. The produced ZnS films have been crystallized in a wurtzite structure and had a direct band gap energy of 3.62 eV. The electrical properties of the sample have been studied by an analysis based on the thermally stimulated current spectra in the temperature range of 40-300 K with various heating rates. A set of curves of I (T) for varying initial density of filled traps at a heating rate of {beta} {sub 2}=0.06 K s{sup -1} indicate that the observed peaks in the TSC curve of polycrystalline ZnS films have first-order features. In order to evaluate the trap parameters of ZnS films, we have used curve-fitting method. The values of the frequency factor ...

Energy Technology Data Exchange (ETDEWEB)

In this study, WO{sub 3} thin films were grown on glass substrates using an aqueous solution containing tungstate (NH{sub 4}){sub 2}WO{sub 4} as precursor. The substrate temperature incremented from 250 to 500 deg. C, by steps of 50 deg. C. The structural properties were investigated using XRD, atomic force microscopy and scanning electronic microscopy techniques. Microprobe analyses showed that a balanced stoichiometric composition was obtained for thin films prepared at T{sub s} = 350 and 400 deg. C. The X-ray diffraction analyses showed different structure crystallography in function of the substrate temperature. Moreover, films deposited at 400 deg. C were annealed in air for 2 h at 450 and 500 deg. C, respectively and the structural changes due to heat treatment were studied. Finally, the optical properties of these films were carried out using optical measurements of transmittance T({lambda}) and reflectance R({lambda}) spectra in 300-1800 nm domain. The refractive and absorption ...

International Nuclear Information System (INIS)

Electrodeposition of semiconducting iron oxide (Fe_2O_3) thin film was carried out from an alkaline sulphate bath. A 0.1 M ferrous sulphate (FeSO_4#centre dot#7H_2O) was complexed with 0.1 M citric acid. By addition of 1 N NaOH, pH of the solution was made alkaline (pH=9) and deposition of iron oxide (Fe_2O_3) thin films was carried out potentiostatically at room temperature (300 K). From cyclic voltametry (CV), electrochemical studies were carried out for deposition of iron oxide thin films. The XRD studies reveal that Fe_2O_3 with epsilon (#epsilon#) phase having monoclinic crystal structure is formed. By observing scanning electron microscope (SEM), it is seen that iron oxide films were homogeneous, uniform and well covered to surface of the substrate. Grain size was found to be in nanometers range from XRD analysis. The optical band gap of Fe_2O_3 thin film was estimated to be 1.90 eV. Electrical resistivity was order of 10"4 #OMEGA# cm. ...

International Nuclear Information System (INIS)

The effect of electron and ion beam irradiation on the Sisub(LVV) Auger spectra of SiO_2, Si_3N_4 and Si-oxynitride films was measured by the relative intensity of the 92 eV signal, characteristic for the formation of 'free' silicon during irradiation. While in Si-oxynitride the beam effects were almost negligible, some damage was found in Si_3N_4, but SiO_2 appeared to be extremely sensitive for electron and ion beam irradiation. By low energy electron loss spectroscopy of ion bombarded SiO_2 and Si_3N_4 films new electron states due to broken Si-O and Si-N bonds could be determined within the band gap of the insulators. The measured energy losses were interpreted by means of electron energy level schemes of the amorphous films. (author).

International Nuclear Information System (INIS)

The structural, morphological and optical properties of vacuum-evaporated CdTe thin films were investigated as a function of substrate temperature and post-deposition annealing without and with CdCl2/treatment at 400 C for 30 min. Diffraction patterns are almost the same exhibiting higher preferential orientation corresponding to (111) plane of the cubic phase. The intensity of the (111) peak increased with the CdCl2/annealing treatment. The microstructure observed for all films following the CdCl2/annealing treatment are granular, regardless of the as-deposited microstructure. The grain sizes are increased after the CdCl2/annealing treatment but now contain voids around the grain boundaries. The optical band gaps, Eg, were found to be 1.50, 1.50 and 1.48 eV for films deposited at 200 K and annealed without and with CdCl2/treatment at 400 C for 30 min respectively. A progressive sharpening of the absorption edge upon heat treatment particularly ...

Energy Technology Data Exchange (ETDEWEB)

Recently, a drive laser for an S-band (2.86 GHz) rf photoinjector, designed to provide a pulse that has a flat temporal and spatial profile, has been built, commissioned, and put into service as part of the LLNL Compton-scattering monoenergetic {gamma}-ray source program. This laser is based on an all-fiber oscillator and front-end amplification system, and provides both the laser light to generate the electrons as well as the rf signal that is amplified to accelerate them. Now, a new 11.424 GHz photoinjector is being developed, which has required a revised design for the laser system. The higher frequency has placed more stringent requirements on the synchronization stability, delivered pulse length, and pulse rise times to maintain the desired emittance. Presented here are the overall design and measured performance of the current system and a discussion of what changes are being made to address observed shortcomings and more demanding requirements to make the ...

International Nuclear Information System (INIS)

We present the results of a comprehensive study of the temperature dependences of the quantum efficiency for ultraviolet detectors based on GaAs, GaP and 4H--SiC Schottky structures, and on Si, GaAs p-n structures. For ultraviolet detectors based on Schottky structures, the quantum efficiency increases with increasing temperature for all photon energies, even including the semiconductor intrinsic absorption region. On the other hand, for ultraviolet detectors based on p-n structures, the quantum efficiency is practically temperature independent in the semiconductor intrinsic absorption region. The change in the quantum efficiency for the GaAs and Si detectors is less than 0.01% per degree. To explain the measurements, a variable trap occupancy model is presented. Subsurface imperfections of the semiconductor cause fluctuations in the profile of the conduction band and the valence band edges. In the presence of an electric ...

Energy Technology Data Exchange (ETDEWEB)

Successful interface engineering requires compositional and electronic material characterization as a prerequisite for understanding and intentionally generating interfaces in photovoltaic devices. The paper gives an overview with several examples, all referring to Cu(In,Ga)(S,Se){sub 2} ('CIGSSe')-based solar cells, with an emphasis on characterization using highly specialized methods, such as elastic recoil detection analysis, X-ray emission spectroscopy and photoelectron spectroscopy using synchrotron and ultraviolet light for excitation, inverse photoemission spectroscopy and Kelvin probe force microscopy. First, the determination of the depth profile of the band gap energy E{sub g} in the absorber layer is demonstrated. The modification of E{sub g} towards both interfaces is discussed in terms of beneficial electronic effects. Next, the interface between absorber and buffer layers with alternative and promising non-toxic ...

Science.gov (United States)

Room-temperature continuous-wave (cw) operation is achieved in the MBE (molecular-beam epitaxy)-grown InGaP/InGaAlP double-heterostructure (DH) visible laser diodes with a threshold current of 110 mA. The lasing wavelength and threshold current density under pulsed operation are 666 nm and as low as 3.9 kA/cm/sup 2/, respectively. This result is achieved by the introduction of H/sub 2/ into the growth chamber during growth, the continuous growth from one layer to the next layer, and the introduction of a GaAs buffer layer. InGaP/InGaAlP quantum well structures are also grown. From photoluminescence measurements, the conduction-band discontinuity ..delta..E/sub c/ is estimated to be 0.43 of the band-gap difference ..delta..E/sub g/. Furthermore, the multiquantum-well (MQW) structure is found to be stable under thermal treatment at temperatures as high as 750 /sup 0/C. Room-temperature pulsed operation of InGaP/InGaAlP MQW laser diodes is ...

International Nuclear Information System (INIS)

In this letter, the effect of vacancies generated by preirradiated laser on dopant diffusion and activation in preamorphized silicon substrate has been studied. Laser-induced melting in silicon was used to generate excess vacancies near the maximum melt depth before silicon substrate amorphization and subsequent boron implantation. We demonstrate that by matching the preirradiated laser melt depth with the implant amorphize depth, it can effectively reduce the silicon self-interstitials released from the end-of-range defect band. The results show great suppression in boron transient enhanced diffusion and significant removal of end-of-range defects. This is attributed to the recombination of laser-generated excess vacancies with preamorphizing induced free silicon interstitials at the end-of-range region.

Energy Technology Data Exchange (ETDEWEB)

Calculating work-function modifications for flat-lying conjugated molecules on extended metal surfaces using density functional theory (DFT) is an extremely resource intensive task. This prevents fast screening of new molecules for their potential to optimize metal work functions for good electron or hole injection in organic electronic devices. We present a semi-classical model, which avoids that problem. This is achieved by identifying the dominant processes occurring at the interface between metal and adsorbate in the pinning-regime, which are then parameterizing their description using band-structure DFT calculations for a small training set With the resulting interdependent equations at hand, only simple gas-phase calculations are needed to predict the work-function changes induced by new molecules. The model is tested for ten molecules on three different metal surfaces, where it shows excellent agreement with photoelectron spectroscopy ...

Energy Technology Data Exchange (ETDEWEB)

Abstracts are presented of 63 papers on the following topics: large-scale optimization, interior-point methods, algorithms for optimization, problems in control, network optimization methods, and parallel algorithms for optimization problems.

Energy Technology Data Exchange (ETDEWEB)

The optoelectronic and excitonic properties in a series of linear acenes are investigated using range-separated methods within time-dependent density functional theory (TDDFT). In these highly-conjugated systems, we find that the range-separated formalism provides a substantially improved description of excitation energies compared to conventional hybrid functionals, which surprisingly fail for the various low-lying valence transitions. Moreover, we find that even if the percentage of Hartree-Fock exchange in conventional hybrids is re-optimized to match wavefunction-based CC2 benchmark calculations, they still yield serious errors in excitation energy trends. Based on an analysis of electron-hole transition density matrices, we also show that conventional hybrid functionals overdelocalize excitons and underestimate quasiparticle energy gaps in the acene systems. The results of the present study emphasize the importance of a range-separated and ...

Science.gov (United States)

UV dwarf star evolution, using central and gap star models emphasizing photoneutrino emission

International Nuclear Information System (INIS)

Analysis of steady-state and transient photoconductivity measurements at room temperature performed on c-axis oriented GaN nanowires yielded estimates of free carrier concentration, drift mobility, surface band bending, and surface capture coefficient for electrons. Samples grown (unintentionally n-type) by nitrogen-plasma-assisted molecular beam epitaxy primarily from two separate growth runs were examined. The results revealed carrier concentration in the range of (3-6)x10"1"6 cm"-"3 for one growth run, roughly 5x10"1"4-1x10"1"5 cm"-"3 for the second, and drift mobility in the range of 500-700 cm"2/(V s) for both. Nanowires were dispersed onto insulating substrates and contacted forming single-wire, two-terminal structures with typical electrode gaps of #approx =#3-5 #mu#m. When biased at 1 V bias and illuminated at 360 nm (3.6 mW/cm"2) the thinner (#approx =#100 nm diameter) nanowires with the higher background doping showed an abrupt ...

Energy Technology Data Exchange (ETDEWEB)

The 4025/2 bands in [sup 177]Ta which are ''identical'' to the neighboring even-even [sup 176]Hf groundstate band have been extended to higher angular momentum. These bands in the two nuclei are seen to diverge from each other in the region of the first i[sub 13/2] neutron alignment. The lower observed crossing frequency for the 4025/2 bands indicates a lower deformation for these bands compared to [sup 176]Hf. Extensions to the h[sub 9/2] 5411/2 yrast band are also reported. (orig.)

Energy Technology Data Exchange (ETDEWEB)

Due to the cyclical human life, utility loads appear to be cyclical too. During daytime when most factories are in operation, the electricity demand is very high. On the contrary, when most people are sleeping from midnight to daybreak, the electric load is very low, usually only half of the peak load amount. To meet this large gap between peak load and light load, utilities must idle many generation plants during light load period while operating all generation plants during peak load period no matter how expensive they are. This low utilization factor of generation plants and uneconomical operation have sparked utilities to invest in energy storage devices such as pumped storage plants, compressed air energy storage plants, battery energy storage systems (BES) and superconducting magnetic energy storage systems (SMES) etc. Among these, pumped storage is already commercialized and is the most widely used device. However, it suffers the limit of available sites and ...

Science.gov (United States)

Not Available

Energy Technology Data Exchange (ETDEWEB)

The ternary compound CuInS{sub 2} is attractive for solar cells due to its band gap of 1.54 eV which borders the optimum value necessary for conversion of a solar spectrum. Recently, works on thin film cells based on this material (ZnO/CuInS{sub 2}) has been reported to show efficiency as high as 11.4%. In this paper, the orientation and the morphology of CuInS{sub 2} sprayed films are determined by the means of X-ray diffraction and scanning electron microscopy. Sprayed CuInS{sub 2} films deposited onto a transparent Pyrex substrate with standard fabrication parameters show a chalcopyrite structure with a preferential orientation (1 1 2). A model based on the calculation of the relative dielectric function {epsilon} has been performed in order to obtain the profile of variation of this parameter and to understand the optical behavior of this material via its transmittance and reflectance in visible and near-infrared regions (0.35-2.5 {mu}m). ...

International Nuclear Information System (INIS)

We have demonstrated that optical images can be stored in transparent lead-lanthanum-zirconate-titanate (PLZT) ceramics by exposure to near-UV light with photon energies greater than the band gap energy of approx. equal to 3.35 eV. The image storage process relies on optically induced changes in the switching properties of ferroelectric domains (photoferroelectric effect). Stored images are nonvolatile but can be erased by uniform UV illumination and simultaneous application of an electric field. Although high quality images, with contrast variations of >= 100:1 and spatial resolution of approx. equal to 10 #mu#m, can be stored using the photoferroelectric effect, relatively high exposure energies (approx. equal to 100 mJ/cm"2) are required to store these images. This large exposure energy severely limits the range of possible applications of nonvolatile image storage in PLZT ceramics. We have recently found from studies of H, He and Ar ...

International Nuclear Information System (INIS)

Iron doped semiconducting nanoparticles Sn1-xFexO2 with x=0, 0.001, 0.002, 0.003, 0.004, 0.01 and 0.03 were prepared by a sol-gel method. The X-ray diffraction, Transmission Electron Microscopy measurements confirm the rutile structure with no impurity phase. The three characteristic lines of electron spin resonance (ESR) are observed in the doped samples for all compositions, which is a clear evidence for rhombic Fe3+ in rutile phase. The line width of ESR increases with increase in Fe concentration due to induced disorder. The spin-pumping effect is observed at temperatures below 250 K for the samples with x=0.01 and 0.03. However, based on the Curie-Weiss susceptibility, iron is in paramagnetic state and is subject to weak antiferromagnetic interaction. Blue shift in the optical band gap is observed with increase in the Fe content. -- Graphical abstract: The ESR spectra reveal that the nature of Fe in Sn1-xFexO2 samples is isolated rhombic ...

Energy Technology Data Exchange (ETDEWEB)

Two window layer materials, Al{sub 0.51}In{sub 0.49}P (E{sub g} = 2.3 eV) and Ga{sub 0.51}In{sub 0.49}P (E{sub g} = 1.88 eV) were compared for gas-source and solid-source MBE grown GaAs and Ga{sub 0.84}In{sub 0.16}As{sub 0.68}P{sub 0.32} (E{sub g} = 1.55 eV) solar cells. Due to the wider band-gap of Al{sub 0.51}In{sub 0.49}P, the increased spectral response was observed for both GaAs and Ga{sub 0.84}In{sub 0.16}As{sub 0.68}P{sub 0.32} material based solar cells. In the case of the GaAs cells, the short-circuit current density was observed to increase from 32.5 mA/cm{sup 2} to 34.4 mA/cm{sup 2} with the Al{sub 0.51}In{sub 0.49}P window layer at AM0. Similar improvement was observed for the Ga{sub 0.84}In{sub 0.16}As{sub 0.68}P{sub 0.32} solar cells.

International Nuclear Information System (INIS)

The crystal structure, electronic structure, and photoluminescence properties of EuxSi6-zAlz-xOz+xN8-z-x (x=0-0.1, 0xMySi6-zAlz-x-yOz+x+yN8-z-x-y (M=2Li, Mg, Ca, Sr, Ba) have been studied. Single-phase EuxSi6-zAlz-xOz+xN8-z-x can be obtained in very narrow ranges of x?0.06 (z=0.15) and z2+ ions can be incorporated into nitrogen-rich Si6-zAlzOzN8-z. The Eu2+ ion is found to occupy the 2b site in a hexagonal unit cell (P63/m) and directly connected by six adjacent nitrogen/oxygen atoms ranging 2.4850-2.5089 A. The calculated host band gaps by the relativistic DV-X? method are about 5.55 and 5.45 eV (without Eu2+ 4f5d levels) for x=0 and 0.013 in EuxSi6-zAlz-xOz+xN8-z-x (z=0.15), in which the top of the 5d orbitals overlap with the Si-3s3p and N-2p orbitals within the bottom of the conduction band of the host. EuxSi6-zAlz-xOz+xN8-z-x shows a strong green emission with a broad Eu2+ band centered at about ...

International Nuclear Information System (INIS)

In this paper, we show that boron transient enhanced diffusion can be reduced to different extents by varying the distribution of nitrogen atoms in the junction. This is attributed to the relative location of nitrogen atoms with respect to boron profile and end-of-range defect band, affecting the interactions between dopants and defects upon annealing. In addition, variations in boron dopant activation and deactivation are also observed. Similar to fluorine co-implantation, it is proposed that nitrogen atoms react with vacancy point defects to form nitrogen-vacancy clusters that will trap the interstitials emitted from end-of-range defects. However, we report that the interstitial sink efficiency of nitrogen atoms is not as good as the co-implanted carbon atoms, which is noticed from the dopant deactivation curves. In terms of extended defect evolution, the results clearly indicate that end-of-range defects can be stabilized by choosing the ...

Energy Technology Data Exchange (ETDEWEB)

In this paper the authors present the first emitter efficiency results for the thin film 40 percent Er-1.5 percent Ho YAG (Yttrium Aluminum Garnet, Y3Al5O12) and 25 percent Ho YAG selective emitter at 1500 K with a platinum substrate. Spectral emittance and emissive power measurements were made (1.2 less than lambda less than 3.2 microns). Emitter efficiency and power density are significantly improved with the addition of multiple rare earth dopants. Predicted efficiency results are presented for an optimized (equal power density in the Er, (4)I[sub 15/2]-(4)I[sub 13/2] at 1.5 microns, and Ho, (5)I[sub 7]-(5)I[sub 8] at 2.0 micron emission bands) Er-Ho YAG thin film selective emitter.

DEFF Research Database (Denmark)

Udgivelsesdato: DEC

Science.gov (United States)

Thin-film solar cells on flexible, lightweight, space-qualified substrates provide an attractive approach to fabricating solar arrays with high mass-specific power. A polycrystalline chalcopyrite absorber layer is among the new generation of photovoltaic device technologies for thin film solar cells. At NASA Glenn Research Center we have focused on the development of new single-source precursors (SSPs) for deposition of semiconducting chalcopyrite materials onto lightweight, flexible substrates. We describe the syntheses and thermal modulation of SSPs via molecular engineering. Copper indium disulfide and related thin-film materials were deposited via aerosol-assisted chemical vapor deposition using SSPs. Processing and post-processing parameters were varied in order to modify morphology, stoichiometry, crystallography, electrical properties, and optical properties to optimize device quality. Growth at atmospheric pressure in a horizontal hotwall reactor at 395 C ...

International Nuclear Information System (INIS)

There are 173 three quasiparticle rotational bands, out of which 38 bands display signature splitting and sometimes a signature inversion also. The observed signature splitting is basically due to the higher order Coriolis coupling and calculation based on particle rotor model (PRM) are in progress

CERN Document Server

A simple analytical model of the barrier discharge in a long gap between opposing plane electrodes is developed. It is shown that the plasma density becomes uniform over large part of the gap in the course of the discharge development, so that one can speak of a formation of a dynamic positive column. The column completely controls the dynamics of the barrier discharge and determines such characteristics as the discharge current, discharge duration, light output, etc. Using the proposed model, all discharge parameters can be easily evaluated

Science.gov (United States)

Nonparabolicity of the heavy hole band in diamond-like semiconductors, which occurs within the framework of the three band model with the perturbation from the other bands taken into account according to the Loewdin procedure, is studied. A direct dependence of nonparabolicity on the band anisotropy (caused by the different effect of Gamma/sub 15c/ and Gamma/sub 12c/ bands) and the inverse dependence on the magnitude of the spin-orbit splittiing is established. A connection between the effective mass of heavy holes and their energy is obtained, which is valid for the majority of diamond-like semiconductors, except for materials with a very strong nonparabolicity of the band of silicon type

International Science & Technology Center (ISTC)

Determination of Special Molybdenum Alloys Optimal Structure Using the Cybernetic Method

Science.gov (United States)

Space Network Ku-band service. ... Completed GLAST mission schedule and budget assessment .... Utilize Ku band SN link (TDRSS) for science data return ...

Science.gov (United States)

The bands may be classified as primary if they merge into the eyewall encircling the eye of the storm, or secondary if they are disconnected from the ...

KoreaScience (Korea)

Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Lifetimes have been measured for a dipole band in {sup 139}Sm using DSAM. The deduced B(M1) and B(E2) values as well as B(M1)/B(E2) ratios are compared with calculations in the framework of the TAC (Tilted Axis Cranking) and SPAC (Shears mechanism with Principal Axis Cranking) models. The dipole band in {sup 139}Sm can be considered as a magnetic rotational band with a prolate or triaxial nuclear deformation. (orig.)

KoreaScience (Korea)

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J-STORE (Japan)

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Science.gov (United States)

ICU telemedicine uses audiovisual conferencing technology to provide critical care from a remote location. Research is needed to best define the optimal use of ICU telemedicine, but efforts are hindered by methodological challenges and the lack of an organized delivery approach. We convened an interdisciplinary working group to develop a research agenda in ICU telemedicine, addressing both methodological and knowledge gaps in the field. To best inform clinical decision-making and health policy, future research should be organized around a conceptual framework that enables consistent descriptions of both the study setting and the telemedicine intervention. The framework should include standardized methods for assessing the preimplementation ICU environment and describing the telemedicine program. This framework will facilitate comparisons across studies and improve generalizability by permitting context-specific interpretation. Research based on ...

Energy Technology Data Exchange (ETDEWEB)

Systematic studies of the NdFeAsOF superconducting energy gap using point-contact Andreev-reflection (PCAR) spectroscopy are presented. At low temperatures the PCAR conductance spectra show a pair of gap-like peaks at about {+-} (4-7) mV and in most cases also a pair of humps at around {+-} 10 mV. Fits to the s-wave two-gap model of the PCAR conductance allowed to determine two superconducting energy gaps in the system. However, the energy-gap features disappear at T* = 15-20 K, much below the particular T{sub c} of the junction under study. At T* a zero-bias conductance (ZBC) peak emerges, which at higher temperatures usually overwhelms the spectrum with an intensity significantly higher than the conductance signal at lower temperatures. Possible causes of this unexpected temperature effect are discussed. In some cases the conductance spectra show just a reduced conductance around ...

Science.gov (United States)

We adapt the Jain-Taylor (2003) shear-ratio geometric lensing method to measure the dark energy equation of state, w = pv/?v and its time derivative from dark matter haloes in cosmologies with arbitrary spatial curvature. The full shear-ratio covariance matrix is calculated for lensed sources, including the intervening large-scale structure and photometric redshift errors as additional sources of noise, and a maximum likelihood method for applying the test is presented. Decomposing the lensing matter distribution into dark matter haloes we calculate the parameter covariance matrix for an arbitrary experiment. Combining with the expected results from the cosmic microwave background (CMB) we design an optimal survey for probing dark energy. This shows that a targeted survey imaging 60 of the largest clusters in a hemisphere with five-band optical photometric redshifts to a median galaxy depth of zm = 0.9 could measure w0 ? w(z = 0) to a marginal ...

Energy Technology Data Exchange (ETDEWEB)

This paper presents a new method for the determination of the energy gap of superconductors. The V/sub max//kT versus ..delta../kT curve was calculated from tunneling theory. The maximum voltage in differential conductance V/sub max/ was measured from the electron tunneling spectrum. From V/sub max//kT and the curve, one can easily calculate the energy gap value ..delta... This method is simple, and the accuracy almost approaches that of the curve-fitting method.

Energy Technology Data Exchange (ETDEWEB)

A new method for determining the energy gap of a superconductor using the maximum in the differential conductance curve of electron tunneling spectrum is given in this paper. The V/sub max//kT versus ..delta../kT curve was calculated from tunneling theory. V/sub max/, the voltage of the conductance maximum, can be measured from electron tunneling spectrum. ..delta../kT can be found from this curve, then the energy gap ..delta.. can be calculated. This method is simple, fast and accurate. The accuracy almost approaches that of the curve fitting method.

Science.gov (United States)

Not Available

Science.gov (United States)

... Briefly, a standard detonator (normally the Scale 1 Gap Test Donor, comprising an exploding bridgewire to initiate a low density PETN pellet and ...

International Nuclear Information System (INIS)

The disrupted magnetic braking theory for the period gap of cataclysmic variable systems is used to study the binary evolution of low-mass main-sequence-like stars with white dwarf companions. The model is able to reproduce the observed location and width of the gap provided that the average mass transfer rates above the upper edge of the gap are greater than about 1.9 x 10 to the -9th solar masses/yr. For the case of angular momentum loss by magnetic braking, the slope of the mass transfer rate with respect to orbital period is shown to range from 3.4 to 3.7. For the evolutionary sequences considered, the He-3 abundance at the surface of the secondary exceeds 0.0015 after the complete mixing phase, resulting in modifications in the nuclear burning development of nova explosions. 31 refs.

Energy Technology Data Exchange (ETDEWEB)

Energy flows in deep inelastic electron-proton scattering are investigated at a centre-of-mass energy of 296 GeV for the range Q{sup 2}{>=}10 GeV{sup 2} using the ZEUS detector. A comparison is made between events with and without a large rapidity gap between the hadronic system and the proton direction. The energy flows, corrected for detector acceptance and resolution, are shown for these two classes of events in both the HERA laboratory frame and the Breit frame. From the differences in the shapes of these energy flows we conclude that QCD radiation is suppressed in the large-rapidity-gap events compared to the events without a large rapidity gap. (orig.)

Energy Technology Data Exchange (ETDEWEB)

Our Andreev reflection measurements (Phys. Rev. Lett. 87 (2001) 137005) along with other experiments have led to a general consensus that MgB{sub 2} is a multiband superconductor with two main superconducting gaps closing at the same T{sub c}. Here we show the behavior of the small gap as a function of the temperature and magnetic field. This gap is isotropic with T{sub c} of the bulk material but with a specific small (crossover) critical magnetic field of about 1 T much lower than the real H{sub c2}. The latter field is anisotropic and is rather governed by the large gap and strongly anisotropic Fermi surface of the material.

Science.gov (United States)

... Title : FINITE ELEMENT OPTIMIZATION OF FIELD CONFIGURATION FOR THE EDDY CURRENT TESTING OF ROLLER BEARING RIB RINGS. ...

British Library Electronic Table of Contents (United Kingdom)

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...

Energy Technology Data Exchange (ETDEWEB)

Lithium isotope separation by displacement chromatography is studied using fundamental principles; the equations are derived assuming theoretical stages in lithium adsorption bands. The concentration profiles in the band are calculated numerically under unsteady state.

Science.gov (United States)

... to-noise density than the uplink budget has (74.2 ... in heav:, point-to-point link applications with ... 11.7 Expanded bands allocated (Ku band) (500 MHz ...

Energy Technology Data Exchange (ETDEWEB)

The effects of dilute impurity doping on charge-density wave (CDW) structures and gaps in NbSe{sub 3} 1T-TaS{sub 2} and 2H-NbSe{sub 2} have been studied by using a scanning tunneling microscope (STM) operating at 4.2 K. In Fe doped samples of NbSe{sub 3} the STM spectroscopy measurements indicate that the added impurities can significantly shift the CDW energy gaps. In NbSe{sub 3}, Fe reduces both CDW gaps by 25-30%, and produces changes in the conductance structure relative to the pure material. The images of Fe{sub 0.01}NbSe{sub 3} show that all three surface chains in the unit cell still carry a strong CDW modulation with no evident disorder. However, a change in the relative amplitudes of the high and low temperature CDWs is detected. The effects of Co and Ni impurities on the gaps in NbSe{sub 3} have also been studied. While Co increases both by 25-30%, Ni increases only the high temperature ...

Energy Technology Data Exchange (ETDEWEB)

The authors are developing MP-TOUGH2 for exploiting massively parallel computers. The goals of this effort are to (1) create a data-parallel subsurface transport code for solving larger problems than currently practical on workstations, (2) write portable code that can take advantage of scalability to run on machines with more processors, and (3) minimize the necessity for additional validation and verification of the resulting code. The initial strategy they have followed is to focus on optimizing the generic and time-consuming task of linear equation solution while leaving the bulk of TOUGH2 unmodified. In so doing, they have implemented a massively parallel direct solver (MPDS) that takes advantage of the banded structure of TOUGH2 Jacobian matrices. The authors have compared timings of the iterative conjugate gradient solvers DSLUBC, DSLUCS, and DSLUGM written in Fortran77 for the front end with the MPDS which uses the data parallel unit. ...

Energy Technology Data Exchange (ETDEWEB)

Lifetimes have been measured in the {pi}h{sub 9/2} (yrast) and {pi}i{sub 13/2} (excited) bands in the nuclei {sup 181}Ir and {sup 187}Au using the Recoil Distance Method (RDM). The results clearly indicate that the {pi}i{sub 13/2} band exhibits an increased deformation over the {pi}h{sub 9/2} band, in keeping with the premise that the delayed crossing in this band is due to enhanced quadrupole deformation. (author). 3 refs, 1 fig, 2 tab.

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

International Nuclear Information System (INIS)

Bone marrow is one of the most radiosensitive organs. Irradiation causes a marked decrease in the total number of hematopoietic cells in the bone marrow. The reticular meshwork structure of marrow stromal cells, however, is relatively resistant to irradiation. Unimpaired stromal cell structure has been thought to be a prerequisite for the repopulation of hematopoietic cells during recovery from the effects of irradiation. The reticular framework is maintained by cell adhesion apparatuses such as gap junctions. The in vitro radiobiologic survival values of a cloned stromal cell line, H-1/A, were studied (n = 1.8, D0 = 138 cGy). Radiation doses of up to 4000 cGy had no detectable effects on the production of colony-stimulating factor 1. H-1/A cells communicate with each other via gap junctions as determined by the sensitive dye-transfer method. Gap-junctional communication between H-1/A cells was resistant to different levels ...

International Nuclear Information System (INIS)

The accurate prediction of local hot spot during normal operation is important to ensure core thermal margin in a very high temperature gas-cooled reactor because of production of its high temperature output. The active cooling of the reactor core determining local hot spot is strongly affected by core bypass flows through the inter-column gaps between graphite blocks and the cross gaps between two stacked fuel blocks. The bypass gap sizes vary during core life cycle by the thermal expansion at the elevated temperature and the shrinkage/swelling by fast neutron irradiation. This study is to investigate the impacts of the variation of bypass gaps during core life cycle as well as core restraint mechanism on the amount of bypass flow and thus maximum fuel temperature. The core thermo fluid analysis is performed using the GAMMA+ code for the PMR200 block-core design. For the analysis not only are some ...

Energy Technology Data Exchange (ETDEWEB)

Recently, the public has become aware of keywords like ''Quantum computer'' or ''Quantum cryptography''. Regarding their potential application in solid state based quantum information processing and their overall benefit in fundamental research quantum dots have gained more and more public interest. In this context, quantum dots are often referred to as ''artificial atoms'', a term subsuming their physical properties quite nicely and emphasizing the huge potential for further investigations. The basic mechanism to be considered is the theoretical model of a two-level system. A quantum dot itself represents this kind of system quite nicely, provided that only the presence or absence of a single exciton in the ground state of that structure is regarded. This concept can also be expanded to the presence of two excitons (bi-exciton). Transitions between the relevant levels can be ...

International Nuclear Information System (INIS)

Authors obtained T1-weighted MRI images of the femoral head after fracture of the femoral neck and classified the signals into four patterns to investigate the sequential changes of the femoral head. The T1-weighted MRI images obtained initially after femoral neck fracture showed a normal pattern in 10 of the 15 hip joints studied. MRI images obtained subsequently still showed the normal signal pattern in eight of the 10 hip joints which had shown the normal pattern in the first MRI, while two of the 10 joints subsequently showed a band pattern. The joint with the homogeneous pattern in the first MRI subsequently showed a band pattern. Of the three joints with an inhomogeneous pattern in the first MRI, two joints showed a subsequent band pattern, and the other a normal pattern. The joints which showed a band pattern continued to show a similar band pattern. Eventually, all hip ...

International Nuclear Information System (INIS)

The newly discovered oxypnictide family of superconductors show very high critical temperatures of up to 55 K. Whilst there is growing evidence that suggests a nodal order parameter, point contact Andreev reflection spectroscopy can provide crucial information such as the gap value and possibly the number of energy gaps involved. For the oxygen deficient NdFeAsO_0_._8_5 with a T_c of 45.5 K, we show that there is clearly a gap value at 4.2 K that is of the order of 7 meV, consistent with previous studies on oxypnictides with lower T_c. In addition, taking the spectra as a function of gold tip contact pressure reveals important changes in the spectra which may be indicative of more complex physics underlying this structure. (rapid communication)

International Nuclear Information System (INIS)

This paper discusses the mechanisms of gas breakdown at low values of pressure and inter-electrode gap, i.e. in the vicinity of the Paschen minimum. In this area of pressure and inter-electrode gap values, breakdown occurs either through gas or vacuum mechanisms, and also the so called anomalous Paschen effect appears. Electrical breakdown of electropositive, electronegative and noble gases has been investigated theoretically, experimentally and numerically. Based on the results obtained, regions in which particular breakdown mechanisms appear have been demarcated. Special attention has been devoted to the anomalous Paschen effect as well as to the avalanche vacuum breakdown mechanism.

British Library Electronic Table of Contents (United Kingdom)

The design and operating principle of a small (50 mm in diameter and 100 mm in height) ???-73C vacuum spark gap are described. It is shown that it can be efficiently switched using a control circuit with a low (?900 V) supply voltage, which is based on an inductive energy storage and a diode opening switch that forms a high-voltage igniting pulse with a rise time of nanosecond duration. The ???-73C switching process is investigated at different rise times of igniting voltage pulses and different igniting current amplitudes. The results of tests of the spark gap operating in regimes of switching current pulses with an amplitude of 12 kA and a rise time of 800 ns are presented.

British Library Electronic Table of Contents (United Kingdom)

In most previous studies of topology optimization, commercial programs, such as Optistruct, ANSYS, and MSC Patran, usually were used during implementation. Such commercial programs are not easy to use and entail time and cost. In addition, it is difficult to confirm results with reference to individual stages of optimization. For addressing this disadvantage, a topology optimization program, which is based on the C language, is developed in this study. This is a very convenient and powerful program for users to conduct topology optimization by using all density methods and homogenization methods in compliance with the methodology. For verifying the developed program, first of all, topology optimization was implemented by using density methods to evaluate the strain energy density of a cant...

UK PubMed Central (United Kingdom)

BackgroundPrior research links optimism to physical health, but the strength of the association has not been systematically evaluated.PurposeFull Text Available

Science.gov (United States)

Sep 18, 2009 ... It is proposed to develop desensitized optimal filtering ... in robust and/or adaptive generalized Kalman and Sigma-Point filters for ...

Energy Technology Data Exchange (ETDEWEB)

The purified integral membrane protein, band 3, from human erythrocytes was inserted into egg lecithin liposomes. The insertion of band 3 was determined from thermal transition data from the analysis of the C-H stretching region bands recorded at temperatures from 25 to -22[sup o]C. Raman spectra show that band 3 considerably broadens and lowers the thermal transition of egg lecithin liposomes, suggesting the insertion of band 3. The band 3-inserted liposomes were irradiated with gamma-rays (40 Gy) and the radiation target groups were determined by the analysis of the structural sensitive Raman bands in the 1600-1700 cm[sup -1] (amide I), 1200-1300 cm[sup -1] (amide III) and 550-1030 cm[sup -1] (side chain amino groups) regions. The radiation-sensitive groups as identified from Raman spectra in the region 550-1030 cm[sup -1] are tyrosines ...

UK PubMed Central (United Kingdom)

The effect of TP (triosephosphates:glyceraldehyde-3 phosphate, GAP, +dihydroxyacetone phosphate, DHAP) on respiration, phosphorylation and matrix ATP/ADP ratios of isolated oat mesophyll mitochondria...Full Text Available

International Nuclear Information System (INIS)

We compare experimental data for temperature dependence of the magnetic order parameter and the magnetic excitations (spin waves) in materials with a quenched orbital moment and a well-defined spin quantum number. It is observed that the thermal decrease of the two quantities proceeds according to the same analytical function of the type y(T)=1-cT"#epsilon# with an identical exponent #epsilon#. This power function applies not only asymptotically for T->0 but holds over a wide temperature range. The exponent #epsilon# is universal, i.e. independent of spin order type and lattice symmetry and depends only on the dimensionality of the relevant interactions and on whether the spin quantum number is integer or half-integer. The different T"#epsilon# functions are identified as representations of stable universality classes. The fact that order parameter and magnetic excitations follow the same T"#epsilon# function shows that the two quantities belong to the same universality class. The ...

UK PubMed Central (United Kingdom)

Electronic and structural properties of antiphase boundaries in group III-V semiconductor compounds have been receiving increased attention due to the potential to integration of optically-active III-V...Full Text Available

UK PubMed Central (United Kingdom)

CF-23“The biggest stumbling block for biological sciences turned out to be synthetic organic chemistry” – Elias A. Zerhouni, Former NIH Director in Chemical...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

This paper represents a parametric study of the amplification factor to account for rebound effects in the Energy Balance Method. Of the 66 distinct cases we chose for our parametric study, the amplification factor of 1.1 seems sufficient except in four borderline cases where the carbon steel pipes are small or have very small gaps between the pipes and the pipe whip restraints. We conclude that the amplification factor generally decreases as the parameters gap size, hinge-to-break distance and overhang increase.

International Nuclear Information System (INIS)

Experiments are described on a plasma cathode with biased grids to prevent entry of ions into the electron extraction gap. The cathode has potential applications to the generation of high-current pulsed electron beams. Operation at 20 A/cm"2 is theoretically possible. The source combines the low average power consumption of a plasma cathode with many of the attractive features of thermionic cathodes, such as space-charge-limited extractor gap electron flow, fast turn-on, and no diode closure. Initial experiments are reported at the 2 A/cm"2 level for pulse lengths to 160 #mu#s.

International Nuclear Information System (INIS)

The Gamma Physics (GaP) program of physical phenomena investigation is proposed on #gamma#p, #gamma#e and #gamma##gamma# colliders at TeV energies. The program contains specialized software (CompHEP system) created for automation of particle interaction processes calculations in the framework of various gauge models. Preliminary physical results are presented (heavy quark production, W, Z production, supersymmetry etc.), and further software development is suggested. (R.P.) 22 refs., 8 figs., 4 tabs.

International Nuclear Information System (INIS)

Hitherto in this laboratory, ionization coefficients alpha and attachment coefficients #eta# have been determined from Townsend's discharge experiments by a curve-fitting method. However, the method proved to be laborious, Formulae have been derived in this paper to give value of alpha and #eta# as a function of Isubo, Isub1 and Isub2 where Isubo is the photoelectric current at a gap setting d and Isub2 the current at another gap setting 2 d. The values of alpha and #eta# obtained give currents in agreement to within 3% in the best cases with the observed currents.

Energy Technology Data Exchange (ETDEWEB)

High-spin states in the neutron-rich nuclei {sup 172,173}Yb have been populated in a {sup 170}Er({sup 7}Li,(p,d,t)xn) incomplete-fusion reaction and the emitted {gamma}-radiation was detected with the GASP array. The signature partners of the 7/2{sup +}[633] rotational band of the odd-N {sup 173}Yb isotope have been newly established and were observed up to spin values of (45/2{sup +}) and (43/2{sup +}), respectively. The ground-state band of the even-even nucleus {sup 172}Yb has been observed up to a spin value of (22{sup +}). No band crossings were found in these bands. To explain this observation, it is proposed that the static pair field is absent, considering that the neutron odd-even mass differences reach for these nuclei very small values and that the band crossing is absent in cranked shell modell calculations without pairing. The results indicate, however, that strong ...

Energy Technology Data Exchange (ETDEWEB)

Cretaceous and Tertiary strata are known from outcrop in the northeast part of the area, while older rocks are presented in the southwest. The major structures are, from north to south: the Pedley Thrust, Coalspur Triangle Zone (formerly called Coalspur Anticline), Entrance Syncline, Mercoal Thrust, Brazeau Flats, Brazeau Thrust, Brazeau Syncline, Grave Flats Thrust, Cadomin syncline and Nikanassin Thrust. The economic coal seams of the Tertiary Coalspur Formation are of high volatile C rank and are present in three parallel bands in the Entrance Syncline and Coalspur Triangle Zone, where they have been mined extensively in the past. The Mercoal band is the southernmost and dips about 30[degree] to the northeast. The Coalspur band is in the middle and dips generally to the southwest. The Robb band is the northernmost band, contains northeast dipping strata and is less deformed than ...

International Nuclear Information System (INIS)

A graphic approach, terms a Genetic Activity Profile (GAP), was developed to display a matrix of data on the genetic and related effects of selected chemical agents. The profiles provide a visual overview of the quantitative (doses) and qualitative (test results) data for each chemical. Either the lowest effective dose or highest ineffective dose is recorded for each agent and bioassay. Up to 200 different test systems are represented across the GAP. Bioassay systems are organized according to the phylogeny of the test organisms and the end points of genetic activity. The methodology for producing and evaluating genetic activity profile was developed in collaboration with the International Agency for Research on Cancer (IARC). Data on individual chemicals were compiles by IARC and by the US Environmental Protection Agency (EPA). Data are available on 343 compounds selected from volumes 1-53 of the IARC Monographs and on 115 compounds identified ...

CERN Document Server

Several types of X-band high power loads developed for several tens of MW range were designed, fabricated and used for high power tests at X-band facility of KEK. Some of them have been used for many years and few units showed possible deterioration of RF performance. Recently revised-design loads were made by CERN and the high power evaluation was performed at KEK. In this paper, the main requirements are recalled, together with the design features. The high power test results are analysed and presented

KoreaScience (Korea)

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Science.gov (United States)

... Descriptors : *QUEUEING THEORY, *APPROXIMATION ... MODELS, OPTIMIZATION, STOCHASTIC PROCESSES ... Categories : TERMINAL FLIGHT ...

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

KoreaScience (Korea)

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KoreaScience (Korea)

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KoreaScience (Korea)

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KoreaScience (Korea)

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KoreaScience (Korea)

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KoreaScience (Korea)

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Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

KoreaScience (Korea)

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CERN Document Server

Two-dimensional generalization of the original peak finding algorithm suggested earlier is given. The ideology of the algorithm emerged from the well known quantum mechanical tunneling property which enables small bodies to penetrate through narrow potential barriers. We further merge this ``quantum'' ideology with the philosophy of Particle Swarm Optimization to get the global optimization algorithm which can be called Quantum Swarm Optimization. The functionality of the newborn algorithm is tested on some benchmark optimization problems.

Wastenet

... Second, in drag as a member of the all-girl band which provides his camouflage. And last as a fake oil millionaire - out to seduce Marilyn - played as a wonderful homage to Cary Grant. \\

International Nuclear Information System (INIS)

... alpha beams energy-level transitions gamma spectra iridium 187 iridium 189

Science.gov (United States)

Lichen striatus begins similarly to lichen planus, with small bumps (papules), but over a period of days expands to form a long streak or band of affected ...

Science.gov (United States)

... thus can function as switches -6 ... Akkari, "Optical Channel Waveguide Switch and Coupler ... Wide-Band Guided Wave Acousto-Optic Bragg Diffraction ...

International Nuclear Information System (INIS)

The self-consistent-pseudopotential method is applied to the A-15 compounds Nb_3Ge and Nb_3Al. The Fermi energy is found to lie in a region of very flat bands having a bonding character along the Nb chains. Comparison with the band structures of the (nonexistent) A-15 materials Nb_3Nb and Nb_3/sup asterisk/ (chains only) suggest that the p states on the Ge and Al atoms are instrumental in determining the position of the Fermi level. There is little evidence for rigid-band behavior in the Nb_3Al/sub x/Ge/sub 1-x/ system. Studies of the effects of chain dimerization in Nb_3Ge suggest that states at R and M are more likely candidates to participate in structural transitions than states at GAMMA or X.

Energy Technology Data Exchange (ETDEWEB)

The interaction of thermal radiation with conduction and convection in thermally developing absorbing, emitting, nongray gas-particulate turbulent suspension flow through a circular tube is investigated. The contribution of thermal radiation is obtained through evaluation of the total hemispherical emittance of the particulate cloud and through evaluation of single band absorptances for molecular gases, modified to account for the interaction with the particles. The governing differential equation is derived as a (nonlinear) energy equation, coupled with integral equations to find the thermal radiation contributions. The energy equation is solved numerically by an implicit finite difference method with an iterative procedure. Qualitative results for Nusselt numbers are shown for a variety and range of parameters, such as optical thickness of particulates and single molecular gas bands, relative gas band position and ...

Science.gov (United States)

Jan 25, 2006 ... Source positions are determined using matched-filter and centroiding .... The upper 1-sigma statistical error in the full-band counts. ...

DEFF Research Database (Denmark)

Interest in optics for hard X-ray broad-band application is growing. In this paper, we compare the hard X-ray (20-100 keV) reflectivity obtained with an energy-dispersive reflectometer, of a standard commercial gold thin-film with that of a 600 bilayer W/Si X-ray supermirror. The reflectivity of the multilayer is found to agree extraordinarily well with theory (assuming an interface roughness of 4.5 Angstrom), while the agreement for the gold film is less, The overall performance of the supermirror is superior to that of gold, extending the band of reflection at least a factor of 2.8 beyond that of the gold, Various other design options are discussed, and we conclude that continued interest in the X-ray supermirror for broad-band hard X-ray applications is warranted.

International Nuclear Information System (INIS)

The main purpose of this work is to evaluate the role of CT in identifying other morphological signs of met static lymph node involvement from non small cell bronchogenic carcinoma. This is done to improve N staging, a critical step in this disease. In fact, since diameter is the only criterion used to distinguish normal form abnormal lymph nodes, mediastinal CT only has 80% diagnostic accuracy. 137 patients with known or suspected lung cancer were examined with Helical CT during early and late arterial phases (2 min. delay, 3 mm thickness, 5 mm inter slice gap) to depict node characteristics. Mediastinal lymph nodes, located according to the American Thoracic Society mapping, were considered normal when they were not visible or, if visible, less than 1 cm in diameter and of homogeneous density; lymph nodes over 1 cm in diameter and homogenous density were considered reactive. A lymph node was considered metastatic when, independent of size, the following signs ...

Energy Technology Data Exchange (ETDEWEB)

A systematic optimization method of choosing the weighting matrix in linear optimal control system design, under the conditions of prespecified closed-loop dominant eigenvalue locations and feedback gain limit constraints, is presented in this paper. Studies show that with the proposed method one can obtain the desired weighting matrix very quickly and conveniently without the heavy burden of choosing a suitable weighting matrix by trail and error. This method can also easily achieve a reduced-order feedback control system. The linear optimal power system stabilizer designed by using the proposed method produces very good performance.

British Library Electronic Table of Contents (United Kingdom)

A joint experimental and theoretical analyses based on the grounds of DFT anharmonic potential and the use of a variational method allow us to revisit and assign the gas phase spectra of vinylarsine in the mid-IR area until 6300cm-1. Several weak and very weak bands corresponding to overtones and combinations are newly observed and assigned in complement to the fundamental bands.

UK PubMed Central (United Kingdom)

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

Science.gov (United States)

Middleware deployed to help TCP performance over links with large ... Boeing Connex (Ku-Band); INMARSAT Swift 64; TrackNet" 2.0 (Ku-Band); G2.5/G3/G4. General ... Incremental deployment may be difficult; High Link budgets; Link Delay ...

British Library Electronic Table of Contents (United Kingdom)

This paper reports the results of in situ observation of fatigue crack growth in a ferrite?pearlite steel. Stress intensity factor range (?K) decreasing/increasing and constant-?K fatigue tests have been carried out. In banded pearlite orientation, intense crack branching was observed which leads to fatigue crack retardation. Crack closure during the test was monitored to understand the fatigue crack growth behaviour.

International Nuclear Information System (INIS)

To calculate the energy band structures in semiconductors using the relativistic augmented plane wave method, atomic potential and charge density are needed, which are calculated by self-consistent method. Wave function for one electron is determined by solving the Dirac equation with the Hartree-Fock equation based on the slater's exchange potential. The results of calculation for Cu"+"1 are given. (Author).

CERN Document Server

This paper describes a study of comparison of global and one-dimensional local optimization methods to operating system scheduler tuning. The operating system scheduler we use is the Linux 2.6.23 Completely Fair Scheduler (CFS) running in simulator (LinSched). We have ported the Hackbench scheduler benchmark to this simulator and use this as the workload. The global optimization approach we use is Particle Swarm Optimization (PSO). We make use of Response Surface Methodology (RSM) to specify optimal parameters for our PSO implementation. The one-dimensional local optimization approach we use is the Golden Section method. In order to use this approach, we convert the scheduler tuning problem from one involving setting of three parameters to one involving the manipulation of one parameter. Our results show that the global optimization approach yields better ...

International Nuclear Information System (INIS)

The absorption spectra of plutonium ions in nitric acid have been described. There is a characteristic change in the absorption spectra of Pu v in lithium nitrate solutions. In 2 M-lithium nitrate a new peak at 969 nm and high absorption at 1200 nm are noticed. A decrease in the absorption by about 20% and the appearance of a new shoulder at 1120 nm in 6 M-lithium nitrate are found. There is no change in the spectrum in 4 M-lithium nitrate. The absorption spectra of plutonium ions in the spectral range 200 - 400 nm are interesting. All plutonium ions have an intense band in the region 250 - 260 nm as well as a less intense and rather diffuse band at 320 - 330 nm in lithium nitrate solutions the sharp band at 250 - 260 nm has disappeared. This suggests that this band is very sensitive to the environmental field. The band is probably produced by 5 F"q#-># 5 f"q"-"1 6 d transition ...

British Library Electronic Table of Contents (United Kingdom)

An Otto cycle engine with internal and external irreversibilities of friction and heat leakage, in which the heat transfer between the working fluid and the environment obeys linear phenomenological heat transfer law [q ?? ?(T ?1)], is studied in this paper. The optimal piston motion trajectory for maximizing the work output per cycle is derived for the fixed total cycle time and fuel consumed per cycle. Optimal control theory is applied to determine the optimal piston trajectories for the cases of with and without piston acceleration constraint on each stroke and the optimal distribution of the total cycle time among the strokes. The optimal piston motion with acceleration constraint for each stroke consists of three segments, including initial maximum acceleration and final maximum decel...

Energy Technology Data Exchange (ETDEWEB)

The detection of explosives is a notoriously difficult problem, especially at stand-off distances, due to their (generally) low vapor pressure, environmental and matrix interferences, and packaging. We are exploring optimal dynamic detection to exploit the best capabilities of recent advances in laser technology and recent discoveries in optimal shaping of laser pulses for control of molecular processes to significantly enhance the standoff detection of explosives. The core of the ODD-Ex technique is the introduction of optimally shaped laser pulses to simultaneously enhance sensitivity of explosives signatures while reducing the influence of noise and the signals from background interferents in the field (increase selectivity). These goals are being addressed by operating in an optimal nonlinear fashion, typically with a single shaped laser pulse inherently containing within it coherently locked ...

Energy Technology Data Exchange (ETDEWEB)

Interference between the crossover leg of the Reactor Coolant System(RCS) and the Pipe Whip Restraints(PWR) has brought a degradation issue of the integrity of the Reactor Coolant System in Westinghouse type Nuclear Power Plants(NPPs) of Korea. According to the gap inspection carried out during planned overhaul (year 2000), interference between the crossover leg and the PWR was found in each RCS loop. This plant has had the high vibration problem on the RC pump 'B'. The reason for the high vibration in the RC pump 'B' had been massively surveyed and it was found that the crossover leg of RCS contacted with the PWR in hot condition. Since the contact between the crossover leg and the PWR changes the dynamic characteristics of the piping system for the RCS, this is considered as one reason for the high vibration. And a possibility of overstress on the crossover leg due to the contact with the PWR should be evaluated. Through ...

UK PubMed Central (United Kingdom)

The brain maintains internal models of its environment to interpret sensory inputs and prepare actions. While behavioral studies demonstrated that these internal models are optimally adapted...Full Text Available

UK PubMed Central (United Kingdom)

BackgroundThe aim of this study was to compare and to validate different dose calculation algorithms for the use in radiation therapy of small lung lesions and to optimize the treatment...Full Text Available

Science.gov (United States)

The highly variable and intermittent pollutant concentrations and flowrates associated with wet-weather events in combined sewersheds necessitates the use of storage-treatment systems to control pollution.An optimized combined-sewer-overflow (CSO) control system requires a manage...

UK PubMed Central (United Kingdom)

Cancer treatment with ionizing radiation is often compromised by organ motion, in particular for lung cases. Motion uncertainties can significantly degrade an otherwise optimized treatment plan....Full Text Available

UK PubMed Central (United Kingdom)

Purposes1. To determine the optimal pelvic nodal clinical target volume for post-operative treatment of endometrial cancer. 2. To compare the DVH of different treatment planning...Full Text Available

British Library Electronic Table of Contents (United Kingdom)

The problem of optimizing a horn radiator of electromagnetic waves for the reflection coefficient and the coefficient of transformation of the fundamental mode into higher order modes is solved. Optimization is performed by means of selecting a combined shape of the radiator generatrices.

International Nuclear Information System (INIS)

The Bragg-curve detector of the parallel plate ionization chamber type generates a signal that is a distorted replica of the original Bragg-curve. In result of this distortion, the signal peak height is not only a function of the atomic number of the heavy ion, as it is often stated, but also of the particle mass. This mass effect was studied with the aid of computer simulation, and it was found to be dependent on the Frisch grid to anode gap width and on the detector gas. The charge resolution of the detector is affected very significantly by this mass dependence of the signal peak height. Therefore, a careful selection of the detector gas and the grid to anode gap width is necessary, if good charge resolution over a wide range of heavy ions is required. (orig.).

International Nuclear Information System (INIS)

Morphology of castellated Be tiles from the belt limiter exposed to the JET plasma for 56,000 s was examined on both sides of castellated grooves, on plasma-facing and side surfaces of the tiles. The essential results are (i) deuterium retention in the castellated grooves and in other locations is associated with co-deposition of carbon; (ii) the decay length of deposition in the castellation is around 1.5 mm; (iii) no deuterium is detected in bulk Be; (iv) bridging of gaps by molten beryllium occurred but gaps were not filled with Be; (v) on side surfaces of the tiles the formation of BeO layer was detected at a distance of 20 mm and more from the plasma-facing surface. The consequences for a long-term operation of a reactor-class device with several different plasma-facing materials are addressed.

Energy Technology Data Exchange (ETDEWEB)

The IEA has identified energy efficiency as essential to achieving a sustainable energy future. In order to improve energy efficiency in industry one of the priority areas for further action is the promotion of more and higher quality energy management (EM) activity. However, there are significant gaps in the current implementation of EM. One method of bridging these gaps would be the creation of an EM Action NetworK (EMAK) to bring practical support to energy managers, connect energy managers to energy policy makers, and interconnect these networks globally. The paper describes possible aims, activities, scope, structure, timelines and approaches related to EMAK and looks at specific tasks that would be important in the set-up and implementation.

International Nuclear Information System (INIS)

The electronic structures of platinum group elements (Ru, Os, Rh, Ir, Pd, and Pt) silicides have been calculated. Ir_3Si_5 is a semiconductor with the direct gap of 1.14 eV. Among monosilicides, RuSi and OsSi with the FeSi-type structure are semiconductors with the gap values of 0.21 and 0.41 eV but RhSi, IrSi, PdSi, and PtSi with the MnP-type structure are metals. No semiconducting compounds can be found in other platinum group elements silicides other than known Ru_2Si_3, Os_2Si_3, and OsSi_2.

Environmental Research Database

Objectives1. To establish the present capacity and capability across all the sectors within the UK for - a) Undertaking research in the areas of toxicology and ecotoxicology and environmental hazard and risk assessment work on chemical subtances including emerging containments (e.g. enginerred nanomaterials); and b) Applying these skills in the policy and regulatory context. 2) The range of chemicals involved should include pharmaceutical and medical products, crop protection agents, biocides, vet [continued...]DescriptionThe aim of this project is to identify the current status of the scientific community, areas of expertise, and identify the gaps in skills, knowledge or recruitment. The project will use a questionnaire approach to obtain this information for all sectors of the business community. The analysis will identify the gaps in provision, and areas where investment is needed in future training and/or recruitment.

Science.gov (United States)

... Descriptors : *PROTECTIVE COATINGS, *WATER REPELLENTS, *COMBUSTIBLE CARTRIDGE CASES, COMPUTER PROGRAMS, SOLVENTS ...

Energy Technology Data Exchange (ETDEWEB)

This paper presents a new algorithm for the optimal long-range generation planning for a thermal system with pumped-storage plants. The algorithm is based upon the analytical production costing model developed under the assumption of Gaussian probabilistic distribution of random load fluctuations and plant outages. The optimization problem consists of the master problem to determine the annual investment, and the pumped-storage subproblem to determine the optimal pumped-storage operation. The master problem is formulated as a Hamiltonian minimization problem, and the pumped-storage subproblem is solved using the concept of peak-shaving operation on the original load curve.

International Science & Technology Center (ISTC)

Nanostructured Materials from Impulse Plasma in Liquid: Studying of Physical-Chemical Properties, Optimization of Conditions of Obtaining

KoreaScience (Korea)

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CERN Document Server

Particle Swarm Optimization technique offers optimal or suboptimal solution to multidimensional rough objective functions. In this paper, this optimization technique is used for designing fractional order PID controllers that give better performance than their integer order counterparts. Controller synthesis is based on required peak overshoot and rise time specifications. The characteristic equation is minimized to obtain an optimum set of controller parameters. Results show that this design method can effectively tune the parameters of the fractional order controller.

British Library Electronic Table of Contents (United Kingdom)

A method for automatic optimal feeder design in steel casting processes is presented. The initial design is the casting part (without feeders) which is placed in a suitable mold box. Design of each feeder contains the following steps: determination of the feeder-neck connection point on the casting surface, initial feeder design, feeder shape optimization and feeder topology optimization. Completing designing the first feeder, the method attends to designing the next one, if it is required, and the same procedure will be repeated. In the presented method, feeders are designed in a descending order of their sizes. The feasibility of the presented method is supported with an illustrative example.

International Nuclear Information System (INIS)

X-ray emission spectroscopy (XES) and X-ray photoelectron spectroscopy (XPS) methods were employed in the present paper to investigate the electronic structure of face-centred cubic (fcc) molybdenum dioxide, fcc-MoO_2. For the mentioned compound, the XES O K#alpha# and Mo L#beta#_2_,_1_5 bands reflecting the valence O p- and Mo s,d-like states, respectively, were derived and compared on a common energy scale with the XPS valence-band spectrum. For comparison, the similar experimental studies of the electronic structure were made for a usual orthorhombic form of molybdenum trioxide, MoO_3. Band-structure calculations of fcc-MoO_2 were made using the full potential linearized augmented plane wave (FP-LAPW) method. A rather good agreement of the experimental XES and XPS results and the theoretical FP-LAPW data for the electronic properties of fcc-MoO_2 has been achieved in the present paper. A new near-Fermi ...

Energy Technology Data Exchange (ETDEWEB)

This paper suggests how nonlinear periodic optimal control of a pumped storage plant can be realized. The control problem consists in maximization of the plant benefits over an operational period. An optimal control law is proposed, yielding a bang-off-bang mode of operation. An algorithm for numerical solution of the problem was developed, and its effectiveness was demonstrated by simulation experiments.

Energy Technology Data Exchange (ETDEWEB)

An optimization criterion accounting for the energy and material consumption is defined. The allowed limits of the variations in the technological factors are discussed and the optimization criterion values within these limits are calculated. The analysis presented, demonstrating the significance of the chosen factors for the production cost-price, is of great practical importance. (orig.).

Energy Technology Data Exchange (ETDEWEB)

In this paper, a new design methodology for determining the size, location, type and number of capacitors to be placed on a radial distribution system is presented. The objective is to minimize the peak power losses and the energy losses in the distribution system considering the capacitor cost. A sensitivity analysis based method is used to select the candidate locations for the capacitors. A new optimization method using a Genetic Algorithm is proposed to determine the optimal selection of capacitors. Test results have been presented along with the discussion of the algorithm.

CERN Document Server

We obtain a simple derivation of the optimal quantum state estimation of a two-level system using the no-signaling principle. In particular, we show that the no-signaling principle determines the unique form of the guessing probability, independently to a given figure of merit such as the fidelity or the information gain. This proves that optimal measurements for a two-level quantum system is the same for almost all figures of merit.

Energy Technology Data Exchange (ETDEWEB)

Implementation of an adaptive power system stabilizer (PSS) based on linear optimal control is described in this paper. The generator is identified in real time, and a special 3rd order discrete Riccati equation is solved in each sample interval. Because the output of the generator is fed back directly, the controller can track the system very fast. Experimental studies on a physical model of a power system demonstrate the effectiveness of the proposed adaptive optimal controller.

Energy Technology Data Exchange (ETDEWEB)

The optimization of ethylene furnace operations using cfd-based simulations has been addressed. The optimization problems have been cast into various formulations: the Multidisciplinary feasible (MDF) approach, the All-At-Once (AAO) approach and the Individual discipline feasible (IDF) approach. These approaches mainly differ in their handling of the state equations as constraints, and hence some of the formulations place restrictions on the methods used to solve the state equations.

International Nuclear Information System (INIS)

We have studied in detail the transient enhanced diffusion observed during furnace or rapid-thermal-annealing of ion-implanted Si. We show that the effect originates in the trapping of Si atoms by dopant atoms during implantation, which are retained during solid-phase-epitaxial (SPE) growth but released by subsequent annealing to cause a transient dopant precipitation or profile broadening. The interstitials condense to form a band of dislocation loops located at the peak of the dopant profile, which may be distinct from the band formed at the original amorphous/crystalline interface. The band can develop into a network and effectively getter the dopant. We discuss the conditions under which the various effects may or may not be observed, and discuss conflicting observations on As"+ implanted Si.

Energy Technology Data Exchange (ETDEWEB)

We have studied in detail the transient enhanced diffusion observed during furnace or rapid-thermal-annealing of ion-implanted Si. We show that the effect originates in the trapping of Si atoms by dopant atoms during implantation, which are retained during solid-phase-epitaxial (SPE) growth but released by subsequent annealing to cause a transient dopant precipitation or profile broadening. The interstitials condense to form a band of dislocation loops located at the peak of the dopant profile, which may be distinct from the band formed at the original amorphous/crystalline interface. The band can develop into a network and effectively getter the dopant. We discuss the conditions under which the various effects may or may not be observed, and discuss conflicting observations on As/sup +/ implanted Si.

British Library Electronic Table of Contents (United Kingdom)

In this paper we present the results of our analyses of multidiurnal low-resolution Moderate Resolution Imaging Spectroradiometer (MODIS) thermal data for coal fire-related thermal anomaly detection. Results are presented for data of the Jharia coal mining region of India. We combine three relatively new approaches: first, we use low-resolution MODIS data for coal fire area analyses, which has only been undertaken by a few authors. Second, we analyse data from four different times of day (morning, afternoon, evening and predawn) and for three different bands (MODIS bands 20, 32 and a ratio thereof); and third, we use an unbiased automated algorithm for thermal anomaly extraction of local thermal anomalies. The MODIS data analysed stem from the years 2001 and 2005. In 2001, MODIS data were ...

Energy Technology Data Exchange (ETDEWEB)

High-spin states in {sup 177}Ta were produced using the {sup 170}Er({sup 11}B, 4{ital n}) reaction at 55 and 60 MeV. Considerable extensions have been made to the previously known level scheme, and new structures have been found. {ital B}({ital M}1)/{ital B}({ital E}2) ratios have been extracted for strongly coupled bands. The behavior of the different rotational cascades, in particular the anomalous crossing frequency observed in the [541]1/2{sup {minus}} proton {ital h}{sub 9/2} band and the occurrence of ``identical bands,`` is discussed. Comparisons are made with projected shell model calculations.