A5041848400- Rare-earth and actinide compounds
- Mechanical stress and fatigue analysis
- Electrical Contact Performance and Analysis
- Magnetism in coordination complexes
- Organic and Molecular Conductors Research
- Physics of Superconductivity and Magnetism
- Particle Accelerators and Free-Electron Lasers
- Superconductivity in MgB2 and Alloys
- Particle accelerators and beam dynamics
- Adhesion, Friction, and Surface Interactions
- Advancements in Solid Oxide Fuel Cells
- Theoretical and Computational Physics
- Chemical Looping and Thermochemical Processes
- Mechanical Behavior of Composites
- Optical and Acousto-Optic Technologies
- Fiber-reinforced polymer composites
- Thermal Expansion and Ionic Conductivity
- Magnetic and transport properties of perovskites and related materials
- Electrical Fault Detection and Protection
- Magnetic confinement fusion research
- Photonic and Optical Devices
- Boron and Carbon Nanomaterials Research
- Particle Detector Development and Performance
- Non-Destructive Testing Techniques
- Electric Motor Design and Analysis
Siemens (United Kingdom)
2024
Cockcroft Institute
2011
Daresbury Laboratory
2010-2011
Rutherford Appleton Laboratory
2010
University of Bristol
2005-2010
Texas A&M University
1999
Westinghouse Electric (United States)
1979-1980
We report measurements of the temperature-dependent anisotropies (gamma(lambda) and gamma(xi)) both London penetration depth lambda upper critical field MgB2. Data for gamma(lambda)=lambda(c)/lambda(a) was obtained from lambda(a) lambda(c) on a single crystal sample using tunnel diode oscillator technique. gamma(xi)=H(perp)c(c2)/H(||c)(c2) deduced field-dependent specific heat same sample. Gamma(lambda) gamma(xi) have opposite temperature dependencies, but close to T(c) tend common value...
We present high resolution heat capacity measurements of the organic superconductors kappa-(ET)(2)Cu[N(CN)(2)]Br and kappa-(ET)(2)Cu(NCS)(2) in fields up to 14 T. use field data determine normal state specific hence extract behavior electronic C(el) superconducting zero finite fields. find that both materials for T/T(c) less or similar 0.3, C(el)(H=0) approximately T2 indicating d-wave superconductivity. The are well described by a strong coupling model from our base temperature (T/T(c) 0.1)...
Abstract Understanding how porous structures become rigid and retain their strength or fail over variable saturation ranges is crucial for designing materials with targeted performances under various construction conditions. This especially true in the development of time-dependent viscosities manipulatable advanced geometamaterials. Modeling unconstrained granular columns from microscale (granular temperature) to mesoscale (internal force chains interactions pore fluid) accurately...
The low Curie temperature (T_C approx 28K) and small ordered moment (M_0 0.17 mu_B f.u.^-1) of ZrZn2 make it one the few examples a weak itinerant ferromagnet. We report results susceptibility, magnetization, resistivity specific heat measurements made on high-quality single crystals ZrZn2. From magnetization scaling in vicinity T_C (0.001<|T-T_C|/T_C<0.08), we obtain critical exponents beta=0.52+/-0.05 delta=3.20+/-0.08, T_C=27.50+/-0.05K. Low-temperature show that easy axis is [111]....
We report specific-heat measurements of the organic superconductors $\ensuremath{\kappa}\text{\ensuremath{-}}{(\text{ET})}_{2}\text{Cu}{(\text{NCS})}_{2}$ and $\ensuremath{\kappa}\text{\ensuremath{-}}{(\text{ET})}_{2}\text{Cu}[\text{N}{(\text{CN})}_{2}]\text{Br}$. When magnetic field is rotated in highly conducting planes at low temperature $(T\ensuremath{\simeq}0.4\text{ }\text{K})$, we observe clear oscillations specific heat which have a strong fourfold component. The observed dependence...
The first demonstration of a full-scale working undulator module suitable for future TeV-scale positron-electron linear collider positron sources is presented. Generating sufficient positrons an important challenge these colliders, and using polarized ${e}^{+}$ would enhance the machine's capabilities. In undulator-based source are generated in metallic target via pair production initiated by circularly photons produced helical undulator. We show how design developed considering impedance...
We present measurements of the low-temperature specific heat single crystals $\ensuremath{\kappa}\text{\ensuremath{-}}(\mathrm{BEDT}\text{\ensuremath{-}}\mathrm{TTF}{)}_{2}\mathrm{Cu}[\mathrm{N}(\mathrm{CN}{)}_{2}]\mathrm{Br}$ as a function cooling rate through glasslike structure transition at $\ensuremath{\sim}80\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. find that rapid produces small $(\ensuremath{\lesssim}4%)$ decrease in superconducting temperature accompanied by substantial (up to 50%)...
Brush performance has been investigated with a view to establish whether or not continuous very high-current density operation is feasible for many parallel brushes running under machine environment conditions. The ultimate objective the development of sliding-brush contact systems advanced powerful electrical machines that require large currents in order achieve high efficiencies and small volumes. Using homopolar generator designed purpose, full complement 92 (46 per polarity) was...
We report a de Haas--van Alphen (dHvA) study of the electronic structure Al-doped crystals $\mathrm{Mg}{\mathrm{B}}_{2}$. have measured with $\ensuremath{\sim}7.5%$ Al, which ${T}_{c}$ 33.6 K ($\ensuremath{\sim}14%$ lower than pure $\mathrm{Mg}{\mathrm{B}}_{2}$). dHvA frequencies for $\ensuremath{\sigma}$-tube orbits in doped samples are $\mathrm{Mg}{\mathrm{B}}_{2}$, implying $16\ifmmode\pm\else\textpm\fi{}2\phantom{\rule{0.2em}{0ex}}%$ reduction number holes this sheet Fermi surface. The...
Selection of proper mechanical loading is necessary to assure satisfactory brush operation in rotating electrical machines. Irregularities the moving surface produce forces such as inertia and holder friction which alter contact force. The range force variation depends upon controllable factors system design. For high metal-content brushes operating an inert atmosphere, sliding modeled using theory applicable metallic contacts with conductivity films. Based on this model under conditions...
New measurements of fracture toughness are reported from 8 to 293 K RAL-71a epoxy resin by the means a three-point-bending tests (also called Single-Edge-Notch Bending, SENB) according ISO 13586 or ASTM D5045-14. Tensile stress and modulus on same system between room temperature cryogenic temperatures, as well thermal expansion, cure shrinkage kinetics fit. It is highlighted that there large reduction in at temperatures below 77 ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML"...
The conventional shunt size cannot be maintained with brush body current densities in the range of 1000A/in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> (1.55 MA/m ) and higher. large shunts which are necessary to preserve low-voltage drops acceptable temperatures ate found heavy stiff. Brush voltage drop may also become a significant contributor electrical power loss. With bulky leads, it is difficult avoid adverse mechanical...
Conventional methods for designing mechanically stable solid brush current collection systems are sometimes found inadequate when developing state-of- the-art electrical machines. These rely primarily on the angle relative to rotor as a complete stability parameter. This paper shows that is not dynamic parameter; other parameters important also. Stability boundaries shown functions of and system damping various typical values parameters. The analysis indicates improves with increasing...
Superconducting (SC) undulators can potentially reach a higher field, for short period devices, than permanent magnet devices. The latest design work on proposed superconducting planar undulator being designed in the UK by STFC is presented. initial layout of undulator, including fill factor and cryogenic system Calculations wakefield heating effects due to different vacuum vessels electron beam configurations are also Another important issue effect engineering tolerances pole pieces:...
This paper reports a new 3D isothermal, steady state electrochemical modeling study for tubular solid oxide fuel cells where the testing setup is studied in order to improve distribution and geometry. For model validation, an experimental voltage-current density curve measured house was used. focuses on cell used optimize geometry improved conditions. The mathematical consists of coupling fluid dynamics, electrical conduction, diffusion physics. indicates that flow mal-distribution may be...
Electro-optically wavelength tunable polarization mode converters have been produced in LiNbO 3 substrate using strain-induced coupling. Polarization conversion excess of 82% was achieved at a 701.39 nm for both transverse electric (TE) and magnetic (TM) input polarizations. The maximum efficiency is highly selective with spectral width 1.45 3.2 mm long device. Electro-optic tuning the center linear rate 0.029 nm/V demonstrated.
We report high resolution field dependent specific heat measurements of single‐crystal YBa2Cu4O8 close to the vortex melting temperature Tm. Measurements were performed in fields up 14 T (applied parallel either b or c axes). For both directions Tm a broadened step is seen which consistent with second order phase transition.