Applications of thermal energy storage to process heat and waste heat recovery in the iron and steel industry

The system identified operates from the primary arc furnace evacuation system as a heat source. Energy from the fume stream is stored as sensible energy in a solid medium (packed bed). A steam-driven turbine is arranged to generate power for peak shaving. A parametric design approach is presented since the overall system design, at optimum payback is strongly dependent upon the nature of the electric pricing structure. The scope of the project was limited to consideration of available technology so that industry-wide application could be achieved by 1985. A search of the literature, coupled with interviews with representatives of major steel producers, served as the means whereby the techniques and technologies indicated for the specific site are extrapolated to the industry as a whole and to the 1985 time frame. The conclusion of the study is that by 1985, a national yearly savings of 1.9 million barrels of oil could be realized through recovery of waste heat from primary arc furnace fume gases on an industry-wide basis. Economic studies indicate that the proposed system has a plant payback time of approximately 5 years

Development of aircraft brake materials

The requirements of brake materials were outlined and a survey made to select materials to meet the needs of high temperature brakes. A number of metals and ceramic materials were selected and evaluated in sliding tests which simulated aircraft braking. Nickel, molybdenum tungsten, Zr02, high temperature cements and carbons were tested. Additives were then incorporated into these materials to optimize their wear or strength behavior with particular emphasis on nickel and molybdenum base materials and a high temperature potassium silicate cement. Optimum materials were developed which improved wear behavior over conventional brake materials in the simulated test. The best materials are a nickel, aluminum oxide, lead tungstate composition containing graphite or molybdenum disulphite; a molybdenum base material containing LPA100 (an intermetallic compound of cobalt, molybdenum, and silicon); and a carbon material (P5)

Survival, Development and Population Dynamics of \u3ci\u3eEmpoasca Fabae\u3c/i\u3e (Homoptera: Cicadellidae) on Three Legume Hosts

Survival and development of potato leafhopper, Empoasca fabae, nymphs were measured on alfalfa (Medicago sativa), birdsfoot trefoil (Lotus corniculatus), and red clover (Trifolium pratense). Survival was not significantly different among host plants (mean = 62%). There was no interaction between sex and host plant for developmental time. Males developed significantly faster than females. Developmental time was fastest on alfalfa, intermediate on trefoil, and slowest on red clover. Plots of alfalfa, trefoil, and red clover were planted to compare the seasonal abundance of the potato leafhopper in the three forages. Nymphs were more abundant in trefoil than in alfalfa and red clover late in July, but no differences occurred on the other sample dates. At their peak, adults were more abundant in alfalfa than in trefoil and red clover

A Variational Approach for Minimizing Lennard-Jones Energies

A variational method for computing conformational properties of molecules with Lennard-Jones potentials for the monomer-monomer interactions is presented. The approach is tailored to deal with angular degrees of freedom, {\it rotors}, and consists in the iterative solution of a set of deterministic equations with annealing in temperature. The singular short-distance behaviour of the Lennard-Jones potential is adiabatically switched on in order to obtain stable convergence. As testbeds for the approach two distinct ensembles of molecules are used, characterized by a roughly dense-packed ore a more elongated ground state. For the latter, problems are generated from natural frequencies of occurrence of amino acids and phenomenologically determined potential parameters; they seem to represent less disorder than was previously assumed in synthetic protein studies. For the dense-packed problems in particular, the variational algorithm clearly outperforms a gradient descent method in terms of minimal energies. Although it cannot compete with a careful simulating annealing algorithm, the variational approach requires only a tiny fraction of the computer time. Issues and results when applying the method to polyelectrolytes at a finite temperature are also briefly discussed.Comment: 14 pages, uuencoded compressed postscript fil

The design of aircraft brake systems, employing cooling to increase brake life

A research program was initiated to determine the feasibility of using cooling to increase brake life. An air cooling scheme was proposed, constructed and tested with various designs. Straight and curved slotting of the friction material was tested. A water cooling technique, similar to the air cooling procedure, was evaluated on a curved slotted rotor. Also investigated was the possibility of using a phase-change material within the rotor to absorb heat during braking. Various phase-changing materials were tabulated and a 50%, (by weight) LiF - BeF2 mixing was chosen. It was shown that corrosion was not a problem with this mixture. A preliminary design was evaluated on an actual brake. Results showed that significant improvements in lowering the surface temperature of the brake occurred when air or water cooling was used in conjunction with curved slotted rotors

Evaluation of materials and design modifications for aircraft brakes

A test program is described which was carried out to evaluate several proposed design modifications and several high-temperature friction materials for use in aircraft disk brakes. The evaluation program was carried out on a specially built test apparatus utilizing a disk brake and wheel half from a small het aircraft. The apparatus enabled control of brake pressure, velocity, and braking time. Tests were run under both constant and variable velocity conditions and covered a kinetic energy range similar to that encountered in aircraft brake service. The results of the design evaluation program showed that some improvement in brake performance can be realized by making design changes in the components of the brake containing friction material. The materials evaluation showed that two friction materials show potential for use in aircraft disk brakes. One of the materials is a nickel-based sintered composite, while the other is a molybdenum-based material. Both materials show much lower wear rates than conventional copper-based materials and are better able to withstand the high temperatures encountered during braking. Additional materials improvement is necessary since both materials show a significant negative slope of the friction-velocity curve at low velocities

Diagnostics of the structure of AGN's broad line regions with reverberation mapping data: confirmation of the two-component broad line region model

We re-examine the ten Reverberation Mapping (RM) sources with public data based on the two-component model of the Broad Line Region (BLR). In fitting their broad H-beta lines, six of them only need one Gaussian component, one of them has a double-peak profile, one has an irregular profile, and only two of them need two components, i.e., a Very Broad Gaussian Component (VBGC) and an Inter-Mediate Gaussian Component (IMGC). The Gaussian components are assumed to come from two distinct regions in the two-component model; they are Very Broad Line Region (VBLR) and Inter-Mediate Line region (IMLR). The two sources with a two-component profile are Mrk 509 and NGC 4051. The time lags of the two components of both sources satisfy $t_{IMLR}/t_{VBLR}=V^2_{VBLR}/V^2_{IMLR}$, where $t_{IMLR}$ and $t_{VBLR}$ are the lags of the two components while $V_{IMLR}$ and $V_{VBLR}$ represent the mean gas velocities of the two regions, supporting the two-component model of the BLR of Active Galactic Nuclei (AGN). The fact that most of these ten sources only have the VBGC confirms the assumption that RM mainly measures the radius of the VBLR; consequently, the radius obtained from the R-L relationship mainly represent the radius of VBLR. Moreover, NGC 4051, with a lag of about 5 days in the one component model, is an outlier on the R-L relationship as shown in Kaspi et al. (2005); however this problem disappears in our two-component model with lags of about 2 and 6 days for the VBGC and IMGC, respectively.Comment: 7 pages, 5 figures. Accepted for publication in the Special Issue of Science in China (G) "Astrophysics of Black holes and Related Compact Objects

Classroom Collective Bargaining Simulation : How Close to the Real Thing

Les jeux et les simulations sont devenus un moyen populaire d'enseignement au cours de la dernière décennie. Leur utilisation est fort bien appropriée à un processus comme celui des négociations collectives. Plusieurssketches de négociations sont disponibles et en usage dans plusieurs campus universitaires à l'heure actuelle. Le présent article décrit l'une de ces saynètes telle qu'on la joue à l'université de Washington.Malgré leur popularité et leur valeur apparente au premier coup d'oeil, les jeux et les simulations n'ont été rarement soumis à une véritable épreuve quant à leur caractère réaliste. L'étude des différents aspects de la négociation collective en tant que le comportement des parties est en jeu fournit une occasion de vérifier si les perceptions des négociations simulées se comparent aux perceptions des véritables négociations tant du côté des salariés que du côté des employeurs.On a découvert qu'il n'y avait pas de différence significative entre les principales réparties des aspirants négociateurs et celles des négociateurs syndicaux, surtout si ces derniers sont inexpérimentés. Les différences entre les étudiants et les négociateurs vraiment expérimentés, notamment les négociateurs patronaux, variaient surtout selon leur degré d'expérience et de maturité et en ce que les négociations « jouées » comportent une responsabilité moindre et n'offrent pas d'occasion d'avancement. Dans l'ensemble, on est arrivé à la conclusion que les négociations simulées se rapprochaient pas mal des négociations réelles. En conclusion, l'article suggère quelques moyens de les rendre encore plus réalistes.The use of games and simulations as means of instruction is particularly appropriate to a behavioral process such as collective bargaining. The author describes, analyses and evaluates one which is used at the University of Washingto