Simplified Drift Evaluation of Wall-Frame Structures

Abstract: An idealized model for analysis of multistory buildings subjected to lateral loads is presented. Using a simplified structural model composed of connecting beams and columns, along with a rapid condensation procedure, an approximated lateral stiffness matrix is obtained from which the lateral deformations can be quickly determined. The proposed model is suitable either for preliminary analysis or for quick verification of more complex computational procedures. Commonly used analytical procedures are based on one of the following two approaches: (i] rapid evaluation of story drifts based on oversimplification of structures as specified primarily by building codes (shear systemslstick models), and (ii) detailed modeling of buildings as an assemblage of structural members combined with refined analysis of each individual component (finite element analysis). While the former approach requires only a small amount of data and simple hand computations to carry out the analysis, the latter requires an abundance of information and fairly complicated and elaborate computations requiring computers. However, the first approach leads only to very approximate results often invalidated by severe assumptions and restrictions while the second method produces results which are more comprehensive and accurate. The idealization proposed in this paper is a rational combination of the two approaches leading to more accurate results with only a minimal amount of data. The simplification is obtained by assuming contraflexure points at mid spans of horizontal beams, but not extending the same simplification to vertical elements, as is typically done in simplified design and code approaches. This allows a simple representation of beams as rotational springs coupled to vertical cantilevers representing the columns. The ensuing matrix computations on a vastly reduced and diagonalized stiffness matrix can be carried out with ease on microcomputers. Using the procedure outlined herein, the internal forces in members can be reasonably obtained, and axial stresses can be roughly estimated. An application of the proposed technique is presented using two sample buildings and are compared with results of more rigorous and accurate procedures.     

Call routing to distributed queues: Is FIFO really better than MED?

New services providing automatic call distribution in the network have been one of the most hotly contested areas in the USA telecommunications arena in recent years. This has been fueled by increasing demand from large corporations for intelligent network routing that will keep their geographically distributed telemarketing/service centers operating with maximum efficiency. This paper compares two basic strategies for a network call distributor: a centralized FIFO queue and a distributed queueing strategy called Minimum‐Expected‐Delay (MED). According to MED, a central controller routes each arrival to the node that minimizes its expected delay (waiting time). Our main result qualifies the conventional wisdom that perceives FIFO as optimal. We show that the waiting time under FIFO is not stochastically smaller than that under MED. Furthermore, we prove that the waiting time distribution functions intersect at a single point. Numerical experiments suggest that, for certain performance criteria and over a range of parameters of interest, MED can actually outperform FIFO. This revised version was published online in June 2006 with corrections to the Cover Date.     

Photosynthetic production of Dunaliella biomass from natural salt water and carbon dioxide

A Dunaliella strain has been isolated and grown in a medium containing saline lake water. Using 40% saline water and mixture of CO₂-air (4% CO₂) the algae grew with a specific growth rate of 0.073 h⁻¹. The maximum cell concentration was 5.6 × 10⁷ cells cm⁻³ which corresponded to 3.63 g dm⁻³ of dry biomass. Using 80% saline water, a glycerol concentration of 1.47 g glycerol g⁻¹ of, protein was obtained which amounted to 44.3% of Dunaliella dry weight. Fermentor CO₂ from a continuous yeast culture was also used as carbon source for photosynthetic growth. At 2.5% CO₂ in the exit gas a decrease of the specific growth rate was observed but the final concentration attained was comparable to that obtained with CO₂-air mixtures.     

Redetermination of the standard potential of the mercuric oxide electrode at temperatures between 283 and 363 K and the solubility product constant of mercuric hydroxide

From e.m.f. measurements of the reversible cell H₂ (1 bar) |NaOH(aq)|HgO|Hg at temperatures between 283 and 363 K, the standard potential of the mercuric oxide electrode has been redetermined; its new observed value at 298.15K is 0.926 99 V (acid scale) or 0.09900 V (basic scale). New values of the related Gibbs energies, enthalpies and entropies for the cell reaction and mercuric oxide, HgO, have been calculated therefrom. From literature data for the cell Hg|HgO|NaOH-(aq)|Ag₂O|Ag the standard potential of the silver oxide electrode at 298.15 K has also been redetermined as 1.1713 V (acid scale) or 0.3433 V (basic scale). In parallel, the solubility product constants at 298.15 K for Hg(OH)₂ and for AgOH have been redetermined as 3.13×10^–26 and 1.959×10^–8, respectively. Applications of the mercuric oxide electrode are discussed.     

Distribution and mobility of mercury in soils from an old mining area in Mieres, Asturias (Spain)

Mercury content in soils near abandoned mine wastes in the mercury mining area of Mieres (Asturias, Spain) is highly elevated as a result of the long period of mining and abundant Hg production. In this work, an evaluation of Hg concentration, distribution, and mobility in three soil samples from the immediate vicinity of a chimney used for vapour evacuation during pyrometallurgical treatment of the ore was carried out. For that purpose, total Hg contents were determined for the original samples and their grain-size subsamples. The study of mercury mobility in the original samples and in the different particle-size subsamples was made by the application of a sequential extraction method. Results showed that Hg concentration in soils decreases directly with the distance from the chimney and the dispersion of Hg is not influenced by the topographic height of the site tested. The sample collected in the base of the chimney exhibited appreciable amounts of mobile Hg. In general, a higher Hg concentration was found for the finest particle-size subsamples. Hg mobility was found to be higher for quite developed soils. The sample collected downstream from the chimney showed a significant Hg mobile content as a result of a more intensive weathering. An increase of Hg mobility at decreasing particle size was found in all three analysed samples.     

Fatty acid biosynthesis during embryogenesis in the amphibianBufo arenarum Hensel

The fatty acid composition and biosynthesis of fatty acids were studied during early embryogenesis of the toadBufo arenarum Hensel. The ova and stages up to the 6 1/2 day embryo have similar fatty acid compositions, with ca. 70% unsaturated acids. The eggs and embryo were permeable to acetate and impermeable to palmitic, linoleic, and eicosa-8,11,14-trienoic acid. Labeled acetate was incorporated by the eggs into the saturated acids-lauric, myristic, palmitic, stearic, arachidic, and behenic-and into the unsaturated acids-myristoleic, palmitoleic, oleic, and eicosaenoic acids. During segmentation and gastrulation, de novo biosynthesis of fatty acids increased, desaturation to myristoleic, palmitoleic, and oleic acids was enhanced; and fatty acids were esterified to triglycerides, phosphatidyl choline, and phosphatidyl ethanolamine. The feeding embryo (11 days) changed the pattern of incorporation to less incorporation into triglycerides.     

Gold Stabilized with Iridium on Ceria–Niobia Catalyst: Activity and Stability for CO Oxidation

Topics in Catalysis - Monometallic gold and iridium, and bimetallic gold–iridium on ceria–niobia (Nb2O5–CeO2) catalysts were synthesized by deposition–precipitation with...     

Stabilized β-Bi2O3 nanoparticles from (BiO)4CO3(OH)2 precursor and their photocatalytic properties under blue light

Stabilized tetragonal Bi₂O₃ nanoparticles (β-Bi₂O₃) were obtained by annealing treatments of amorphous Bi-based precursors, obtained by chemical precipitations, at temperatures between 350 and 450?°C. The formation of the stabilized β-Bi₂O₃ phase was possible by using (BiO)₄CO₃(OH)₂ while other precursors such as amorphous bismuth carbonate ((BiO)₂CO₃) and amorphous basic bismuth nitrate (Bi₆O₆(OH)₂(NO₃)₄·2H₂O) led to the formation of the thermodynamically stable monoclinic α-Bi₂O₃ and Bi₅O₇NO₃ phases. The Bi-based precursors were prepared by the chemical precipitation method at room temperature in ethylenediamine-solvent varying the HNO₃/Bi³⁺ molar ratio (10, 26 and 56). The physicochemical properties of the three as-prepared amorphous precursors and the formed-after-calcination β-Bi₂O₃, α-Bi₂O₃ and Bi₅O₇NO₃ phases were analyzed by X-ray diffraction, scanning electron microscopy, thermogravimetry, X-ray photoelectron spectroscopy (XPS), FTIR analysis, diffuse reflectance spectroscopy and surface area by BET method. The photocatalytic activity of all annealed solids containing the β-Bi₂O₃ phase was tested in the photodegradation of the indigo carmine (IC) dye under specific blue light. A schematic diagram of the Bi₂O₃ phases obtained as a function of the annealing conditions and initial amorphous precursor is proposed and explained in terms of the amount of CO₃^2-, NO₃^- and amine (ENH₂²⁺ ? ENH⁺) ions present in each bismuth precursor.