Fringing in tubular permanent-magnet machines: Part I. Magnetic field distribution, flux linkage, and thrust force

This paper extends an analysis developed for tubular permanent-magnet machines to account for the effect of fringing associated with the finite length of the ferromagnetic armature core. The magnetic field distribution, established by using an analytical technique formulated in the cylindrical coordinate system, provides an accurate means of evaluating the effect of the fringing flux on the thrust force and the back-electromotive force. Finite-element calculations confirm the analytically derived results. In Part II of the paper, the analysis is used to predict the cogging force that results from end effects and to facilitate minimization of the force.     

Heterogeneous Plantinum Nucleation and Crystallization of a Heavy-Metal Fluoride Glass

The effect of controlled heterogeneous nucleation by platinum on the crystallization of a ZrF₄-BaF₂-LaF₃-AlF₃-NaF (ZBLAN) glass was studied. Various levels of platinum were incorporated into this glass by a combination of PtCl₂-doping and melting-atmosphere variation. The effect of doping levels and melting conditions on the incorporation of platinum and the subsequent nucleation of crystals was studied by optical microscopy, scanning electron microscopy, differential scanning calorimetry (DSC), and X-ray diffraction. Increased platinum in the glass resulted in an increased number of nucleation sites for the growth of β-ZrF₄-BaF₂ crystals. Analysis of isothermal and ramp-rate DSC measurements indicated that the crystallization of this glass changed from surface controlled to bulk controlled with an increased number of nuclei. This was confirmed by optical microscopy. In addition, Avrami analysis of the isothermal crystallization data gave an accurate approximation of the number of nuclei in the glass.     

Risk-Based Allocation of Distribution System Maintenance Resources

Asset management is an important activity in present day distribution system planning and operation. Utilities are constantly striving to optimize the use of resources available for maintenance while ensuring system reliability is within satisfactory limits. This paper proposes a method to allocate maintenance resources to various distribution system assets. To determine the effects of maintenance, a predictive reliability assessment tool is developed. This paper describes the model on which this tool is based. The results obtained from reliability assessment can be used along with an optimizer to allocate resources to various maintenance tasks in a distribution system.     

Immune recognition of viral antigens

The response exhibited by the immune system to viral and other foreign antigens consists of antibody-mediated and T cell-mediated immunity. Structural and molecular biological studies have shown that the antibody response is tailored to provide exquisite specificity by generating binding pockets that are complementary in shape as well as in charge to the antigen. On the other hand, the cellular response uses T-cell receptors (TCRs) and the major histocompatibility complex (MHC) antigens. Structural information on the TCRs is not yet available, but the crystal structures of several MHC class I molecules have shown how one MHC molecule can bind many different peptide sequences that share only the common anchor residue positions that determine allele specificity. MHC class I interactions with the peptide backbone at the N and C termini explain the high specificity of the binding groove for peptide ligands and suggest a universal mode of recognition for peptides to MHC class I molecules. Peptide-MHC class II interactions are less well understood, although recent structural work has shown important differences in the binding clefts of MHC class I and II that lead to longer peptides being bound to class II molecules. Detailed analysis at the molecular level has indicated that conformational changes in both antibodies and MHC molecules occur upon antigen binding.(ABSTRACT TRUNCATED AT 250 WORDS)     

A low-power, linear, permanent-magnet generator/energy storagesystem

This paper describes the design, analysis and characterization of a linear permanent magnet generator and capacitive energy storage system for generating electrical power from a single stroke of a salient-pole armature. It is suitable for applications that require relatively low levels of electrical power, such as remote electronic locks. An electromagnetic analysis of the generator is described, and a design optimization methodology for the system is presented. Finally, the performance of a prototype is validated against measurements     

Thermal degradation studies of several pyrrone films

The thermal degradation of several polyimidazopyrrolone (pyrrone) films was studied in air and in vacuum over the range of 100–1000°C. by thermogravimetric analysis (TGA), with the use of both isothermal heating and programmed heating rates of 2, 3, 5, and 7.5°C./min. At pressures of 10^?6 torr or less, maximum weight losses average 30% at 800°C. Rates of volatilization and activation energies were derived to provide comparison between these ladder-type polymers. Mass spectrometric analysis of the pyrolysis gases evolved under vacuum conditions showed that CO, CO₂, and H₂O were the primary volatile products and that they were formed throughout the period of weight loss. Approximate correlation between changes in weight and changes in the total pressure for the vacuum tests indicates that mass spectrometric results could provide quantitative as well as qualitative data. The importance of sample history prior to heating and of sample geometry in developing meaningful and reproducible TGA results is aptly demonstrated. The ability of these materials to absorb readily 5–7 wt.-% of water under ambient conditions and the effect of this property upon weight loss measurements are shown.     

Carbon-13 nuclear magnetic resonance spectra of model hydroaromatic hydrocarbons and solvent

Carbon-13 chemical shifts are reported for tetralin, hydrophenanthrenes and hydropyrenes and their alkyl substituted derivatives. Mono- and di- plus tri-aromatic fractions of hydrogenated phenanthrene and pyrene were also examined by carbon-13 n.m.r. and, wherever possible, the components in them identified.     

Automatic generation of alignments for 3D QSAR analyses.

Many 3D QSAR methods require the alignment of the molecules in a dataset, which can require a fair amount of manual effort in deciding upon a rational basis for the superposition. This paper describes the use of FBSS, a program for field-based similarity searching in chemical databases, for generating such alignments automatically. The CoMFA and CoMSIA experiments with several literature datasets show that the QSAR models resulting from the FBSS alignments are broadly comparable in predictive performance with the models resulting from manual alignments.     

Marriage and the spiritual realm: The role of proximal and distal religious constructs in marital functioning.

Ninety-seven couples completed questionnaires about their involvement in joint religious activities and their perceptions regarding the sanctification of marriage, including perceived sacred qualities of marriage and beliefs about the manifestation of God in marriage. In contrast to individual religiousness and religious homogamy (distal religious constructs), these proximal religious variables directly reflect an integration of religion and marriage, and they were associated with greater global marital adjustment, more perceived benefits from marriage, less marital conflict, more verbal collaboration, and less use of verbal aggression and stalemate to discuss disagreements for both wives and husbands. The proximal measures also added substantial unique variance (adjusted R2 change ranged from .06 to .48) to specific aspects of marital functioning after controlling demographic factors and distal religious variables in hierarchical regression analyses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)