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The problem of improving the quality of the current collection process becomes particularly relevant at the high speeds of rolling stock movement. First of all, the quality of current collection is related to the interaction of the pantograph current collector with the contact wire. From the point of view of mechanics this is the process of the interaction of two oscillatory systems with a randomly varying degree of interaction. The analytical consideration of the dynamics of such interaction in the best case (if it is feasible at all) can only lead to probabilistic estimates of quantities interesting from the practical point of view. It was the motivating reason to develop some classes of the models of the reaction of the contact wire to the static and dynamic effects of the pantograph. We found the natural oscillation frequencies of the catenary and their corresponding eigen functions taking into account the structural elements providing an equilasticity of the catenary. [ABSTRACT FROM AUTHOR]

The difficulties of starting a diesel motor at negative ambient temperatures are known. It is primarily connected with the peculiarity of ignition of diesel fuel. At negative ambient temperatures the fuel becomes viscous, and its spraying by the nozzles becomes difficult. This problem is solved by installing various additional pre-starting fuel heaters on fuel filters, main pipeline or in the tank. They are autonomous electrical devices. In this paper we consider a new type of preheater. It simultaneously performs both heating and pumping of diesel fuel. This heater is designed on the basis of an electromechanical converter. One of the distinctive features of this device is the possibility of independent regulation of the amount of heating and pressure of the heated fuel. The analysis showed that the heater has the wide-regulating characteristics, provides the ability to obtain and maintain the specified temperature of the heated fuel, pressure and productivity. This device is high-tech and it is characterized by the high structural reliability. [ABSTRACT FROM AUTHOR]

Monophase ceramics based on silicon oxonitride was obtained in one technological stage, combining the synthesis of the aluminum oxonitride phase and its further densification by hot pressing at 1850°C in a nitrogen atmosphere. The obtained samples were characterized by scanning electron microscopy and X-ray phase analysis; the mechanical properties of the ceramic samples were measured. [ABSTRACT FROM AUTHOR]

The effect of the Al2O3−Y2O3−ZrO2 sintering additive on compaction and mechanical properties of silicon carbide ceramics was studied in this work. The sintering additive was obtained by plasma-chemical synthesis. Sintering ceramic was carried out by hot pressing in the temperature range 1700-1800°C. With an increase in temperature, an increase in density and mechanical properties occurs. The ceramic material has a linear thermal expansion coefficient in the temperature range 20-1600°C equal to 3.9х10−6К−1. [ABSTRACT FROM AUTHOR]

The problem delay-dependent control for discrete systems is considered. The control algorithm is synthesized under conditions of incomplete information about the disturbance model and is based on the optimization of the local criterion, using robust Kalman filtering for systems with unknown input and Markov jump parameter. An example is given to illustrate the proposed approach. [ABSTRACT FROM AUTHOR]

The ion-atom merged-beam apparatus at Oak Ridge National Laboratory in Oak Ridge, Tennessee has been successful in measuring absolute cross sections of charge transfer between atomic ions and hydrogen atoms for many years. Moreover, the first molecular ion measurements with the current version of the apparatus, performed for D2+ + H, are used to benchmark theory between 0.5 - 2 keV/u including vibrationally specific adiabatic theory for the (H2–H)+ complex, the most fundamental ion-molecule two-electron system. The absolute cross section of direct charge transfer in D2+ + H was measured with the merged-beam apparatus between 2.0 keV/u - 10 keV/u, and is presented here. The new measurements agree with McGrath et al. measurements at their lowest energy of 10 keV/u. These new measurements show that, besides the local maximum at 0.1 keV/u observed in our previous measurements, the absolute cross section also has a maximum around 2.2 keV/u, delineating an oscillation-like structure. [ABSTRACT FROM AUTHOR]

We are developing a robotic system for auto-mounting protein crystals from a sample cassette in liquid nitrogen to a goniometer head. A small industrial six joint axis robot is adopted for this system with a custom built actuator. It will be installed at a wiggler protein crystallography beam-line in Pohang Accelerator Laboratory. Our design goal is to make the system applied to every type of sample pins such as a screw or magnetic types of pins with 18mm length. The sample cassette is designed to contain 10 crystals, which is similar to ALS and ACTOR systems. The diameter of a hole is 17 mm for several type caps. It’s bigger than others. A sample Dewar with two type sensors for monitoring liquid nitrogen level can contain 5 cassettes at a time. We designed two types of actuator for holding the cap containing a protein crystal. These whole hardware and software are under development in PAL. Our system and some test results will be introduced in this paper. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

We reviewed present status regarding theoretical approaches for neutrino-induced reactions and neutrino scattering. With a short introduction of relevant data, our recent calculations by distorted-wave Born approximation (DWBA) for quasielastic region are presented for MiniBooNE data. We also discussed that one step-process estimated by the DWBA is comparable to the two-step process, which has been usually used in the neutrino-nucleosynthesis. For much higher energy neutrino data, such as NOMAD data, elementary process approach was shown to be useful instead of using complicated nuclear models. But, in the low energy region, detailed nuclear structure model, such as QRPA and shell model, turn out to be inescapable to explain the reaction data. [ABSTRACT FROM AUTHOR]

The nucleon form factors in free space are usually thought to be modified when a nucleon is bound in a nucleus or immersed in a nuclear medium. We investigated effects of the density-dependent axial and weak-vector form factors on the electro-neutrino (νe) and anti-electro-neutrino (νe) reactions with incident energy Eν ≤ = 80 MeV via neutral current (NC) and charged current (CC) for a nucleon in a nuclear medium or 12C. For the density-dependent form factors, we exploited the quark-meson-coupling (QMC) model, and apply them to the νe and νe induced reactions by NC and CC. In CC reaction, about 5 % decrease of the electro neutrino (νe) reaction cross section on the nucleon is shown to be occurred in normal density, ρ =ρo ~0.15fm-3, and also about 5 % reduction of total 12e cross section on 12C is obtained by the modification of the weak form factors for bound nucleons. Density effects for both cases are relatively small, but they are as large as the effect by the Coulomb distortion of outgoing leptons in the ν-reaction. However, density effects in the anti-electro neutrino (νe) reaction reduced significantly about 30 % the cross sections for both the nucleon and 12C cases. For NC, about 12 % decrease of the total cross section by the νe reaction on the nucleon is obtained at normal density, ρ =ρ0 ~0.15 fm-3, as well as about 18 % reduction of the total νe cross section on 12C, by the modification of the weak form factors of the bound nucleon. However, similarly to the CC reaction, effects of the nucleon property change in the νe reaction reduce significantly the cross sections about 30 % for the nucleon in matter and 12C cases. In this talk, we address that such a large asymmetry in the νe cross sections in both reactions is originated from the different helicities of νe and νe. [ABSTRACT FROM AUTHOR]

Double triangular current profile (DT) gives a high transformer ratio which is the determining factor of the performance of collinear wakefield accelerator. This current profile can be generated using the emittance exchange (EEX) beam line. Argonne Wakefield Accelerator (AWA) facility plans to generate DT using the EEX beam line. We conducted start-to-end simulation for the AWA beam line using PARMELA code. Also, we discuss requirements of beam parameters for the generation of DT. [ABSTRACT FROM AUTHOR]

The interaction of high-power pulsed-laser beam with metal targets in air from 1.06 μm, 5 ns, 3 J/pulse max, Nd:YAG pulsed laser is investigated together with hydrodynamic theories of laser-supported detonation (LSD) wave and multi-material reactive Euler equations. The high speed blast wave generated by the laser ablation of metal reaches maximum velocity of several thousand meters per second. The apparently similar flow conditions to those of reactive shock wave allow one to apply the equations of motion for energetic materials and to understand the explosive behavior of metal vaporization upon laser ablation. The characteristic time at which planar to spherical wave transition occurs is confirmed at low (20 mJ/pulse) to higher (200 mJ/pulse) beam intensities. The flow structure behind the leading shock wave during the early planar shock state is confirmed by the high-resolution multi-material hydrocode originally developed for shock compression of condensed matter. [ABSTRACT FROM AUTHOR]

The results of measurements of the multicharged ions spectra in plasma produced by moderately intense (up to 4×1017 W/cm-2) laser pulses are presented. In the first case, Nd glass laser radiation with energy 1 – 2 J and pulse duration 1.5 ps was focused on the flat solid Teflon target. In the second case, Ti:Sa laser radiation with energy ∼70 mJ and pulse duration 70 and 500 fs was focused onto an N2O gas jet, created by a high-pressure liquid nitrogen cooled, pulsed (10 Hz) nozzle. Profiles of the Lyα lines of F IX ions in Teflon target and O VIII ions in N2O clusters were recorded with a very high spectral resolution λ/δλ ∼ 3000 – 5000. The features (peaks and dips) in the Lyα line profiles were observed. They suggest the existence of intense plasma oscillations with a frequency appreciably lower than the frequency of the laser radiation. The observed X-ray spectra for the plasma satellites of the Lyα doublet of the hydrogen F IX and O VIII ions in plasma were modeled theoretically. It was shown that the resulting doublet profile have a complex structure, which depends nontrivially both on the plasma temperature, density and on the frequency and amplitude of the plasma oscillations. Experimental positions of the satellites and their separations allowed them to be associated with intense electrostatic oscillations with an amplitude E0 ∼ (4–6)×108 Vcm-1 and a frequency ω ∼ (0.7–1)×1015 s-1 for F IX ions and E0 ∼ (0.5 – 1.0)×10 9 V/cm and frequency ω ∼ (0.7–2.4)×1015 s-1 for O VIII, simultaneously. Assuming the oscillation frequency to be determined by the strength of the magnetic field B generated in the plasma, we obtained an estimate of B that is in reasonable agreement with other measurements. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The semiconductor industry has sustained its historical exponential performance gains by aggressively scaling transistor dimensions. However, as devices approach sub-100 nm dimensions, scaling becomes more challenging and new materials are required to overcome the fundamental physical limits imposed by existing materials. For example, as power supply voltages continue to decrease with successive scaling, enhanced carrier mobility using biaxially tensile-strained-Si on SOI or on bulk substrates have become viable options to sustain continual drive current increases without traditional scaling. Although the addition of strained-Si to conventional MOSFET devices is compatible with existing mainstream CMOS process technology, there are new device and process integration challenges, wafer quality monitoring demands, and stringent requirements for film morphology and strain uniformity, imposing new demands on material characterization. Material requirements for strained-Si CMOS devices include homogeneous Si or SiGe film thickness, Ge composition, strain distribution to maintain uniform device performance. Also important are having good interface quality and low defect density (misfit and threading dislocation densities below 1e4/cm2) to ensure high minority carrier lifetimes and transconductance, and low surface roughness (<3Å RMS) to minimize the impact of interface scattering on carrier mobilities. Non-destructive, in-line metrology techniques include spectroscopic ellipsometry (SE) for film thickness and Ge composition, xray reflectivity (XRR) for thickness, density, and roughness measurements, xray fluorescence (XRF) for Ge composition, UV-Raman spectroscopy for channel strain characterization, IR photoluminescence (PL) for defect detection, and xray diffraction (XRD) for film thickness, Ge content, and strain measurement. While most of these techniques are well established in the semiconductor industry, some will require performance enhancements and development for application to volume manufacturing. For example, as wafer test areas continue to shrink, spot sizes must also be reduced. It also becomes more difficult to extend measurements made on large test areas to small device features. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

We demonstrate that self-guiding of intense short pulses in clustered gases can be utilized to generate long plasma channels, which upon expansion form waveguides suitable for propagation of laser pulses at high intensity. This scheme has several advantages over waveguide-generation in non-clustered gases. The absorption of energy by the target depends on the size of the clusters and not on the average density of the gas, which allows greater control of the density encountered by the guided pulse. In particular, electron densities less than 1018 cm-3 are feasible. Moreover, since clusters absorb sub-picosecond pulses very efficiently, channel generation by an auxiliary long-pulse laser is no longer necessary and a considerably simpler setup suffices. The problem of taper at the channel entrance, an old bugbear of side-pumped waveguides in gases, is shown to be significantly reduced. Evidence will be presented of waveguide generation in gases of argon and hydrogen clusters, using different cryogenic sources. A slit source is used for argon, and waveguides < 1 cm could be formed, in which laser pulses with intensity > 1017 Wcm-2 were guided. The results of a propagation code suggest that even longer channels are well within experimental reach. Argon, however, has the disadvantage that a super-intense pulse would likely produce further ionization, and hence suffer ionization induced defocusing. Hydrogen clusters, which can easily be fully ionized, were formed using a more efficient conical nozzle cooled to 90 K, limiting maximum waveguide lengths to < 3 mm. Though these channels are short, there is no obvious reason why a longer target would not allow longer waveguides to be generated, and the experiments demonstrate the utility of this novel scheme. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Composites are considered for many structural (aerospace vehicles, automobiles, trains and ships) applications structural weight. However, impacted composite structures have 50–75% less strength than undamaged structures. The present work experimentally characterizes and explores the response of composite structures with a wide range of structural configurations to both impact and quasi-static loadings. In this study, CF/Epoxy(Carbon Fiber/Epoxy Resin) composite laminates with various curvatures was used. The objective of this study is to find a method for changing the radius of the curvature and to determine how the impact velocity affects the contact force-deflection, damage area and absorbed energy under low-velocity impact loadings. By experimenting with composite structures, we found that there were substantial differences between the responses of a flat-plate and shell to transverse loading. And contact force, damage area, and absorbed energy of the composite shells were a function of curvature radius and impact energy. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

A significant advance in intraundulator electron-beam diagnostics has recently been demonstrated based on coherent optical transition radiation (COTR) imaging. We find signal strengths from a microbunched beam in a UV-visible free-electron laser to be several orders of magnitude higher than that of incoherent optical transition radiation. In addition we report that the far-field images of COTR interferograms carry information about beam size and asymmetry, divergence, and pointing. [ABSTRACT FROM AUTHOR]

There is a strong desire for short wavelength (down to 1 Å), short pulsewidth (<100 fs), high-brightness, transverse, and longitudinally coherent light pulses for use by the synchrotron radiation community. Much effort is ongoing worldwide to advance this desire both experimentally, in theory and design, and politically. One of the ongoing experimental efforts is the low-energy undulator test line (LEUTL) at the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). This experiment is based upon the self-amplified spontaneous emission (SASE) process, a method to attain a next-generation light source. This presentation gires an overview conceming the history and results of next-generation light sources, the results of the LEUTL SASE FEL, and the description of the upcoming first user experiment on LEUTL. We will also briefly review exotic schemes for future, next-generation light sources based upon FELs including biharmonic undulators and the possibility of interfacing of traditional x-ray lasers with FELs. [ABSTRACT FROM AUTHOR]

A series of experiments have been performed to investigate the time dependent interaction of intense laser pulses with mass-limited noble-gas clusters and droplets. The lasercluster interaction was explored using a variable pulse width arrangement whereas the dynamics of the droplets were investigated using a pump probe scheme. The plasma evolution was assessed by monitoring x-ray and extreme ultraviolet emission, as well as light scattering. The observed time scales for clusters and droplets are understood in terms of two time scales natural to the plasma dynamics. We also present, in the case of clusters, a 1D hydrodynamic model of the interaction in which the laser field is treated self-consistently. We find that nonuniform expansion of the heated material results in long-time resonance of the laser field at the critical density plasma layer. These simulations explain the dependence of generation efficiency on laser pulse width. [ABSTRACT FROM AUTHOR]

The AglnS[sub 2] epilayers with a chalcopyrite structure grown using a hot-wall epitaxy (HWE) method have been confirmed to be a high quality crystal. From the optical absorption measurement, the temperature dependence of the energy band gap on AgInS[sub 2]/GaAs was found to be Eg(T) = 2.1365 eV - (9.89 × 10[sup -3] eV) T[sub 2]/(2930 + T). After the as-grown AgInS[sub 2]/GaAs was annealed in Ag-, S-, and In-atmospheres, the origin of point defects of AgInS[sub 2]/GaAs has been investigated by using the photoluminescence (PL) at 10 K. The native defects of V[sub Ag], V[sub s], Ag[sub int], and S[sub int] obtained from PL measurements were classified as a donors or acceptors type. And we concluded that the heat-treatment in the S-atmosphere convertedAgInS[sub 2]/GaAs to an optical p-type. Also, we confirmed that In in AgInS[sub 2]/GaAs did not form the native defects because In in AgInS[sub 2] did exist in the form of stable bonds. [ABSTRACT FROM AUTHOR]

The chalcopyrite AglnS[sub 2] epilayers were grown on the GaAs substrate by using a hot-wall epitaxy (HWE) method. The temperature dependence of the energy band gap of the AgInS[sub 2] obtained from the absorption spectra was well described by the Varshni's relation, Eg(T)=2.1365 eV-(9.89 × 10[sup -3] eV)T[sup 2]/(2930 + T). In addition, we obtained the free exciton binding energy, 0.1115 eV, for the chalcopyrite AglnS[sub 2]/GaAs by using Shay's result. The crystal field and the spin-orbit splitting energies for the valence band of the AglnS[sub 2] have been estimated to be 0.1541 eV and 0.0129 eV, respectively, by means of the photocurrent spectra and the Hopfield quasicubic model. These results indicate that the splitting of the A so definitely exists in the ... 5 states of the valence band of the AglnS[sub 2]/GaAs epilayer. The three photocurrent peaks observed at 10 K are ascribed to the A[sub 1-], B[sub -1], and C[sub -1]-exciton peaks for n = 1. Also, we obtained the A[sub ∞-] and B[sub ∞-] exciton peaks from the PC spectrum at 293 K. Therefore, we conclude that the peaks observed by the photocurrent measurement are the free exciton peaks or peaks due to band-to-band transitions. [ABSTRACT FROM AUTHOR]