to be done in this area. Face recognition is a problem that scarcely clamoured for attention before the computer age but, having surfaced, has involved a wide range of techniques and has attracted the attention of some fine minds (David Mumford was a Fields Medallist in 1974). This singular application of mathematical modelling to a messy applied problem of obvious utility and importance but with no unique solution is a pretty one to share with students: perhaps, returning to the source of our opening quotation, we may invert Duncan's earlier observation, 'There is an art to find the mind's construction in the face!'.

Linear and nonlinear waves, by G. B. Whitham. Pp.636. £50. 1999. ISBN 0 471 35942 4 (Wiley).

Inertial confinement fusion (ICF) is an approach to fusion that relies on the inertia of the fuel mass to provide confinement. To achieve conditions under which inertial confinement is sufficient for efficient thermonuclear burn, a capsule (generally a spherical shell) containing thermonuclear fuel is compressed in an implosion process to conditions of high density and temperature. ICF capsules rely on either electron conduction (direct drive) or x rays (indirect drive) for energy transport to drive an implosion. In direct drive, the laser beams (or charged particle beams) are aimed directly at a target. The laser energy is transferred to electrons by means of inverse bremsstrahlung or a variety of plasma collective processes. In indirect drive, the driver energy (from laser beams or ion beams) is first absorbed in a high‐Z enclosure (a hohlraum), which surrounds the capsule. The material heated by the driver emits x rays, which drive the capsule implosion. For optimally designed targets, 70%–80% of the d...

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Development of the indirect‐drive approach to inertial confinement fusion and the target physics basis for ignition and gain

Interpretation of X-ray Powder Diffraction Patterns . By H. Lipson and H. Steeple. Pp. viii + 335 + 3 plates. (Mac-millan: London; St Martins Press: New York, May 1970.) £4.

X-Ray Diffraction

The 1990 National Academy of Science final report of its review of the Inertial Confinement Fusion Program recommended completion of a series of target physics objectives on the 10-beam Nova laser at the Lawrence Livermore National Laboratory as the highest-priority prerequisite for proceeding with construction of an ignition-scale laser facility, now called the National Ignition Facility (NIF). These objectives were chosen to demonstrate that there was sufficient understanding of the physics of ignition targets that the laser requirements for laboratory ignition could be accurately specified. This research on Nova, as well as additional research on the Omega laser at the University of Rochester, is the subject of this review. The objectives of the U.S. indirect-drive target physics program have been to experimentally demonstrate and predictively model hohlraum characteristics, as well as capsule performance in targets that have been scaled in key physics variables from NIF targets. To address the hohlrau...

The physics basis for ignition using indirect-drive targets on the National Ignition Facility

https://iopscience.iop.org/article/10.1088/1468-6996/11/4/044305/pdf

Present status of amorphous In–Ga–Zn–O thin-film transistors

The deformation behavior of the surrounded Cu stabilized YBCO coated conductor based on the Hastelloy substrate and its influence on the critical current were precisely investigated. The mechanical properties were assessed at room temperature and 77 K. The greatest contribution was brought by two metallic components of the Hastelloy substrate and Cu stabilized layers. The internal strain exerted on the superconducting YBCO layer was determined directly by using synchrotron radiation facilities. The thermally induced residual strain with compressive component decreased during the tensile loading and changed to a tensile component at the force free strain (Aff), at which the internal stress becomes zero in the YBCO layer. Beyond Aff, the increasing rate of internal strain slowed down, suggesting brittle behavior, that is, the formation of micro-cracks. The applied strain dependence of the critical current could be divided into two regions. In the reversible region, the strain dependence obeyed the intrinsic strain effect and was well expressed by the Ekin formula. Beyond the reversible limit, the critical current decreased rapidly with strain. The degradation is suggested to be attributed to the formation of cracks in the YBCO layer. The force free strain evaluated from the mechanical properties was 0.26%. On the other hand, the strain at the critical current maximum was observed to be 0.035–0.012%. These facts suggest re-examining the hypothesis supposing that the critical current maximum appears at the force free strain in YBCO coated conductors.

https://iopscience.iop.org/article/10.1088/0953-2048/22/6/065001/pdf

Internal residual strain and critical current maximum of a surrounded Cu stabilized YBCO coated conductor

Polystyrene foils with surface ripples of 60 or 100 p, m wavelength were irradiated by 0.53 p, m laser light at an intensity of 4 X 10" W/cm . Phase inversion of the rippled shock front was observed at a shock-propagation distance equal to the ripple wavelength. It has been found that the growth of the areal-density perturbation prior to shock breakout is due predominantly to the rippled-shock propagation.

/pdf/dynamic-behavior-of-rippled-shock-waves-and-subsequently-3xywficsod.pdf

Dynamic Behavior of Rippled Shock Waves and Subsequently Induced Areal-Density-Perturbation Growth in Laser-Irradiated Foils

Ultra-fine-grained (UFG) aluminum with a grain size of 260nm was fabricated by annealing a severely plastically deformed A1100 alloy. The resulting UFG aluminum exhibited a 0.2% proof stress (·0.2) that was four times larger than that predicted by the conventional Hall-Petch relation. In this study, the UFG aluminum, the fine-grained aluminum with a grain size of 960nm and the coarse-grained aluminum with a grain size of 4.47µm were prepared. The change in the dislocation density, μ was investigated during tensile deformation using in-situ X-ray diffraction measurements at SPring-8. It was found that as the strain increased, the μ changed in four distinct stages. The first stage was characterized by elastic deformation, and little change in the μ occurred. For the coarse-grained aluminum, this stage was almost absent. In the second stage, the μ rapidly increased until the stress reaches ·II in which the plastic deformation begins to occur at a constant strain rate. In the third stage, only a moderate change in the μ occurred. Finally, in the fourth stage, the μ rapidly decreased as the test pieces underwent fracture. Additionally, it was found that the ·0.2-·I was followed by the conventional Hall-Petch relation in all grain size range. [doi:10.2320/matertrans.L-M2015803]

Evaluation of Dislocation Density for 1100 Aluminum with Different Grain Size during Tensile Deformation by Using In-Situ X-ray Diffraction Technique

A reversible effect of strain on the critical current (Ic) has been reported for REBa2Cu3O7−δ (REBCO) coated conductors. In this study, the strain sensitivity of Ic was compared for GdBCO coated conductors with different crystal orientations. Extremely small strain sensitivity was confirmed from tensile and bending tests at 77 K for a GdBCO film with the [110] direction parallel to the tape length (Gd-F), while a GdBCO film with the [100] or [010] direction parallel to the tape length (Gd-I) has much stronger strain dependence of Ic. To compare the strain sensitivity of Ic based on internal strain, the lattice strain was evaluated for a GdBCO film in a composite conductor by employing a diffraction technique using synchrotron radiation. The lattice strain was determined along both the a- and b-axes for the orthogonal domains that are generated by the twin structure of GdBCO film. A distinct difference in the 2D strain state that depended on the crystal orientation was revealed for the GdBCO coated conductors. In Gd-I, the lattice strains along the axial and lateral directions are tensile and compressive under tensile loading, respectively, that is, the 2D internal strain state is anisotropic. On the other hand, an almost isotropic 2D strain state was confirmed in Gd-F. In addition, the strain components along the crystal axes in Gd-F are much smaller than the axial strain components in Gd-I. This difference in the internal strain state is attributed to the difference in strain sensitivity between the GdBCO coated conductors with different crystal orientations. The contributions of the strain components along the a- and b-axes to Ic are discussed on the basis of the measured strain sensitivities and internal strains for two conductors.

https://iopscience.iop.org/article/10.1088/0953-2048/25/5/054014/pdf

The effect of the 2D internal strain state on the critical current in GdBCO coated conductors

Characterizing of directional solidification mode of Fe-Cr-Ni alloys during welding was performed using intense synchrotron radiation probe. Consequently, the crystal growth in the rapid solidification process was revealed in detail and the peak profile was systematically analyzed in order to acquire the essential information for controlling the weld microstructure. Then, the crystallization timing of the primary and secondary phases was discussed. Furthermore, the possibility of the lattice rotation to commensurate (i) each dendrite and (ii) crystallites in the dendrites is suggested.

Masugu Sato

Papers

Internal residual strain and critical current maximum of a surrounded Cu stabilized YBCO coated conductor

Dynamic Behavior of Rippled Shock Waves and Subsequently Induced Areal-Density-Perturbation Growth in Laser-Irradiated Foils

Evaluation of Dislocation Density for 1100 Aluminum with Different Grain Size during Tensile Deformation by Using In-Situ X-ray Diffraction Technique

The effect of the 2D internal strain state on the critical current in GdBCO coated conductors

In-Situ Observation for Weld Solidification in Stainless Steels Using Time-Resolved X-ray Diffraction