Global patterns of Joule heating in the high-latitude ionosphere

[1] A compiled empirical global Joule heating (CEJH) model is described in this study. This model can be used to study Joule heating patterns, Joule heating power, potential drop, and polar potential size in the high-latitude ionosphere and thermosphere, and their variations with solar wind conditions, geomagnetic activities, the solar EUV radiation, and the neutral wind. It is shown that the interplanetary magnetic field ( IMF) orientation and its magnitude, the solar wind speed, AL index, geomagnetic K-p index, and solar radio flux F-10.7 index are important parameters that control Joule heating patterns, Joule heating power, potential drop, and polar potential size. Other parameters, such as the solar wind number density (N-sw) and Earth's dipole tilt, do not significantly affect these quantities. It is also shown that the neutral wind can increase or reduce the Joule heating production, and its effectiveness mainly depends on the IMF orientation and its magnitude, the solar wind speed, AL index, K-p index, and F10.7 index. Our results indicate that for less disturbed solar wind conditions, the increase or reduction of the neutral wind contribution to the Joule heating is not significant compared to the convection Joule heating, whereas under extreme solar wind conditions, the neutral wind can significantly contribute to the Joule heating. Application of the CEJH model to the 16 July 2000 storm implies that the model outputs are basically consistent with the results from the AMIE mapping procedure. The CEJH model can be used to examine large-scale energy deposition during disturbed solar wind conditions and to study the dependence of the hemispheric Joule heating on the level of geomagnetic activities and the intensity of solar EUV radiation. This investigation enables us to predict global Joule heating patterns for other models in the high-latitude ionosphere and thermosphere in the sense of space weather forecasting.Publishe

Hypotheses on L-H transition

SIGLECopy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

On approximating invariant tori: block iterations and multigrid methods for the associated systems

SIGLEAvailable from TIB Hannover: RN7349(658) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

ASDEX Johann spectrometer

SIGLECopy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

A branch-and-cut approach to physical mapping with end-probes

A fundamental problem in computational biology is the construction of physical maps of chromosomes from hybridization experiments between unique probes and clones of chromosome fragments in the presence of error. Alizadeh, Karp, Weisser and Zweig [AKWZ94] first considered a maximum-likelihood model of the problem that is equivalent to finding an ordering of the probes that minimizes a weighted sum of errors, and developed several effective heuristics. We show that by exploiting information about the end-probes of clones, this model can be formulated as a weighted Betweenness Problem. This affords the significant advantage of allowing the well-developed tools of integer linear-programming and branch-and-cut algorithms to be brought to bear on physical mapping, enabling us for the first time to solve small mapping instances to optimality even in the presence of high error. We also show that by combining the optimal solution of many small overlapping Betweenness Problems, one can effectively screen errors from larger instances, and solve the edited instance to optimality as a Hamming-Distance Traveling Salesman Problem. This suggests a new combined approach to physical map construction. (orig.)SIGLEAvailable from TIB Hannover: RR 1606(96-39) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Recommendations for a modification of ASTM E 1457 to include creep-brittle materials

VAMAS Technical Working Area 19 on High Temperature Fracture of Brittle Materials has developed several new recommendations for determining and analysing the creep crack extension behaviour of creep-brittle materials. These recommendations, most of which are also useful for creep-ductile materials, include: machining narrow starter notches for brittle materials; definition of creep crack initiation; definition of creep toughness; recommendations for conducting creep crack growth tests under the conditions of constant displacement rates or step-wise increments in displacements and/or displacement rates, in addition to the usual constant force method; additional parameters for correlating the creep crack extension rate, such as stress intensity factor, K, C_t parameter, Q* parameter, and rate of #delta#_5 type CTOD, #delta#_5; and criteria for the various correlation parameters. These recommendations are presented in a form which should aid development of national and international standardization of creep crack extension test methods. (orig.)Special print from: Engineering Fracture Mechanics, v. 62 (1999), p. 123-142Available from TIB Hannover: RA 3251(99/E/16) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Investigations of MHD activity in ADSEX discharges

SIGLECopy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman