Fiber Orientation as a Means to Control Formation on the Ultra-Former Through Changes in the Spouting Jet to Wire Speed Ratio and Stock Consistency in the Headbox

The Ultra-Former is a new type of multi-ply board machine. It uses a cylinder mold without a vat and has a stock delivery system that uses a headbox similar to that found on a fourdrinier machine. The board made on the Ultra-Former has several improved qualities over the board made on the conventional type board machines. Of these several improved qualities formation is one of the most important. Formation is important because it affects the physical properties of the finished product. One of the major physical properties affected is the tensile strength of the sheet. The tensile strength is reduced due to the higher probability of premature strain failure in areas of low fiber substance caused by poor formation. Formation is change through the adjustment of five key machine variables found on the fourdrinier type headbox. The spouting jet to wire speed ratio and the consistency in the headbox are the most important of the five variables and the easiest to control. This project involved the controlling of formation through fiber orientation as the most important variables, spouting jet to wire speed ratio and the consistency in the headbox are the most important of the five variables and the easiest to control. This project involved the controlling of formation through fiber orientation as the most important variables, spouting jet to wire speed ratio and consistency in the headbox, are changed. The fiber orientation is deplicted by using a ratio between the machine direction (MD) tensile and cross machine direction (CM) tensile as determined using the zero span tensile test. The results obtained indicate strongly that fiber orientation cannot be used for a formation control because the values are too random. At high degrees of fiber orientation the formation may be good one time and low at another time. Formation tended to be more dependent upon basis weight than fiber orientation

Determination of the phase diagram of the electron doped superconductor Ba(Fe1−x_{1-x}Cox_x)2_2As2_2

Systematic measurements of the resistivity, heat capacity, susceptibility and Hall coefficient are presented for single crystal samples of the electron-doped superconductor Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$. These data delineate an $x-T$ phase diagram in which the single magnetic/structural phase transition that is observed for undoped BaFe$_2$As$_2$ at 134 K apparently splits into two distinct phase transitions, both of which are rapidly suppressed with increasing Co concentration. Superconductivity emerges for Co concentrations above $x \sim 0.025$, and appears to coexist with the broken symmetry state for an appreciable range of doping, up to $x \sim 0.06$. The optimal superconducting transition temperature appears to coincide with the Co concentration at which the magnetic/structural phase transitions are totally suppressed, at least within the resolution provided by the finite step size between crystals prepared with different doping levels. Superconductivity is observed for a further range of Co concentrations, before being completely suppressed for $x \sim 0.018$ and above. The form of this $x-T$ phase diagram is suggestive of an association between superconductivity and a quantum critical point arising from suppression of the magnetic and/or structural phase transitions

Jamming, two-fluid behaviour and 'self-filtration' in concentrated particulate suspensions

We study the flow of model experimental hard sphere colloidal suspensions at high volume fraction $\Phi$ driven through a constriction by a pressure gradient. Above a particle-size dependent limit $\Phi_0$, direct microscopic observations demonstrate jamming and unjamming--conversion of fluid to solid and vice versa--during flow. We show that such a jamming flow produces a reduction in colloid concentration $\Phi_{x}$ downstream of the constriction. We propose that this `self-filtration' effect is the consequence of a combination of jamming of the particulate part of the system and continuing flow of the liquid part, i.e. the solvent, through the pores of the jammed solid. Thus we link the concept of jamming in colloidal and granular media with a 'two-fluid'-like picture of the flow of concentrated suspensions. Results are also discussed in the light of Osborne Reynolds' original experiments on dilation in granular materials.Comment: 4 pages, 3 figure

Pinpointing Gap Minima in Ba(Fe0.94_{0.94}Co0.06)2_{0.06})_{2}As2_2 \textit{via} Band Structure Calculations and Electronic Raman Scattering

A detailed knowledge of the gap structure for the Fe-pnictide superconductors is still rather rudimentary, with several conflicting reports of either nodes, deep gap minima, or fully isotropic gaps on the Fermi surface sheets, both in the $k_{x}-k_{y}$ plane and along the c-axis. In this paper we present considerations for electronic Raman scattering which can help clarify the gap structure and topology using different light scattering geometries. Using density functional calculations for the Raman vertices, it is shown that the location of the gap minima may occur on loops stretching over a portion of the c-axis in Ba(Fe$_{0.94}$Co$_{0.06})_{2}$As$_2$.Comment: 4+ pages, three figure

Band and momentum dependent electron dynamics in superconducting Ba(Fe1−xCox)2As2{\rm Ba(Fe_{1-x}Co_{x})_2As_2} as seen via electronic Raman scattering

We present details of carrier properties in high quality ${\rm Ba(Fe_{1-x}Co_{x})_2As_2}$ single crystals obtained from electronic Raman scattering. The experiments indicate a strong band and momentum anisotropy of the electron dynamics above and below the superconducting transition highlighting the importance of complex band-dependent interactions. The presence of low energy spectral weight deep in the superconducting state suggests a gap with accidental nodes which may be lifted by doping and/or impurity scattering. When combined with other measurements, our observation of band and momentum dependent carrier dynamics indicate that the iron arsenides may have several competing superconducting ground states.Comment: 5 pages, 4 figure

BiFeO3/La0.7Sr0.3MnO3 heterostructures deposited on Spark Plasma Sintered LaAlO3 Substrates

Multiferroic BiFeO3 (BFO) / La0.7Sr0.3MnO3 heterostructured thin films were grown by pulsed laser deposition on polished spark plasma sintered LaAlO3 (LAO) polycrystalline substrates. Both polycrystalline LAO substrates and BFO films were locally characterized using electron backscattering diffraction (EBSD), which confirmed the high-quality local epitaxial growth on each substrate grain. Piezoforce microscopy was used to image and switch the piezo-domains, and the results are consistent with the relative orientation of the ferroelectric variants with the surface normal. This high-throughput synthesis process opens the routes towards wide survey of electronic properties as a function of crystalline orientation in complex oxide thin film synthesis.Comment: 10 pages, 4 figures, Submitted to Applied Physics Letter

Determination of the position of Jupiter from radio metric tracking of Voyager 1

The Voyager 1 spacecraft flew by Jupiter on March 5, 1979. Spacecraft navigation was performed with radio tracking data from NASA's Deep Space Network. In the years since then, there has been a great deal of progress in the definition of celestial reference frames and in determining the orbit and orientation of the Earth. Using these improvements, the radio metric range and Doppler data acquired from the Voyager 1 spacecraft near its encounter with Jupiter have been reanalyzed to determine the plane-of-sky position of Jupiter with much greater accuracy than was possible at the time of the encounter. The position of Jupiter at the time of encounter has been determined with an accuracy of 40 nrad in right ascension and 140 nrad in declination with respect to the celestial reference frame defined by the International Earth Rotation Service. This position estimate has been done to improve the ephemeris of Jupiter prior to the upcoming encounter of the Galileo spacecraft with Jupiter