A New Test to Evaluate the Fire Performance of Residential Sprinklers

Fire tests were conducted using the Underwriters Laboratories (UL) UL 1626 Fire Test for residential sprinklers. The results indicated that sprinkler performance in UL 1626 could not be reproduced due to differences in material flammability properties. This conclusion was reached in a cooperative effort with UL. Factory Mutual Research's Approval fire test that had been redesigned based on UL 1626 was thus subject to the same variability. A new fire test was developed using fuel with controlled material flammability parameters based upon the use of the ASTM E2058 Fire Propagation Apparatus. The new fuel package consists of a wood crib (one half the height of the one which was used in UL 1626) supported over a pan with heptane, two polyether foam cushions (about 60% greater in density than the foam previously used in UL 1626) measuring 34 in by 30 in by 3 in (864 mm by 762 mm by 76 mm) and in (6 mm) Douglas Fir plywood paneling. The new fire test was shown in a series of sprinklered fire tests to provide a reproducible challenge to residential sprinklers comparable to that observed in the Factory Mutual Research and the Los Angeles Residential Test Programs.     

Elastic conformity in Hertzian contacts

The study of elastic conformity within rough surface contacts is presented in terms of a conformity parameter derived as a function of normal load, elastic-modulus and the geometry of asperities within the interface. The parameter can be used in conjunction with the profile structure function to determine the wavelength of features which will elastically conform, and those remaining, which will appear to the contact as roughness. Experimental confirmation of the parameter's ability to define the minimum wavelength of surface asperity conformity is shown through optical studies of the contact interface created when laser-milled steel balls are pressed against a chromium plated glass disc under various loads. Practical applications demonstrated include the parameter's ability to identify surface features responsible for generating vibration in rolling bearings by an elastic percussion mechanism, and to explain interactions between surface roughness structure and the apparent ehd film-thickness generated during rolling contact. The parameter is also shown to reduce to the well known plasticity index when conditions are allowed to approach the elastic limit.     

Sensitivity of juvenile salmonid growth to future climate trends

Seasonal temperature and bioenergetic models were coupled to explore the impacts on juvenile salmonid growth of possible climate‐induced changes to mean annual water temperature and snowpack in four characteristic ecoregions. Increasing mean temperature increases juvenile growth in streams that currently experience cool spring temperatures. In streams with currently warm spring temperatures, an increase shortens the duration of optimal conditions and truncates growth. A loss of snow enhances growth in cool‐summer streams and decreases growth in warm‐summer streams. The relative impacts of such climate change trends will vary significantly across ecoregions. Copyright © 2010 John Wiley & Sons, Ltd.     

CELL-FREE SYNTHESIS OF ETHYL ACETATE BY EXTRACTS FROM SACCHAROMYCES CEREVISIAE

A cell-free preparation has been obtained from Saccharomyces cerevisiae which will synthesize ethyl acetate from ethanol and acetyl-CoA. Ethyl acetate synthesizing activity is stimulated by magnesium ions, the optimal concentration being 8 mM. Subcellular fractionation indicates that the enzyme is associated with material sedimenting at 105 000g .     

A new adaptation of mapping method to study mixing of multiphase flows in mixers with complex geometries

The main objective of the present work is to modify the traditional mapping method for the simulation of distributive mixing of multiphase flows in geometries involving moving parts such as, internal mixers or twin-screw extruders without a limitation on their geometrical periodicity. The periodicity condition, limits the results of traditional mapping method to tracking mapping mesh between specific discrete time intervals or distances for that geometry is repeated, hence, result is only for fixed orientation of rotors. Imaginary domain method is introduced to track mapping mesh from one state to the next free of geometrical periodicity limitations. In this work the method is introduced and its applicability and accuracy is discussed in details. A two-dimensional (2D) simulation of mixing of two Newtonian fluids with different viscosities in an intermeshing internal mixer is used as a test case study. In this example the key issues of ability to predict mixing state in details for all orientations of rotors is presented. To reduce diffusion errors of mapping method in the boundaries of the rotors, mapping mesh refinement technique that relies upon one single reference mesh is also presented.     

Diameter-Controlled Synthesis of Polyaniline Nanofibers

Summary  Various diameters of polyaniline (PANI) nanofibers were easily made by varying the sweep rate in the electrochemical polymerization of the aniline monomer. At a sweep rate of 5 mV/s, the PANI nanofibers have an average diameter of 450 nm with a median of 440 nm. The fibers are short, on the order of a few microns in length, and exhibit a branched geometry. Increasing the sweep rate to 50 mV/s produced longer nanofibers with a smaller average diameter of 200 nm. Nanofibers synthesized at 100 mV/s were noted to be smaller with an average and median diameter of 100 nm. These results illustrate the ease in which the morphology of nanostructured PANI can be altered and indicate that the method has the potential to create multi-diameter fibers or mixed-morphology materials.     

An examination of deviations from hydrodynamic penetration theory

The hydrodynamic theory of penetration (HTP) was first developed in the U.S. during WWII, and independently and essentially simultaneously in England. Since then the theory has proved very useful in understanding and predicting results of many penetration experiments. The assumptions and limitations of HTP were well stated in the initial paper. The most obvious limitation is that, strictly speaking, HTP only applies to hydrodynamic materials, i.e., both the projectile and the target have no strength. But for nearly all cases of interest, penetration does depend on material strengths, even at quite high velocities. Consequently, effects of projectile and target strength on penetration physics have been studied by many researchers, and modified versions of HTP have been proposed. While material strength is an important reason for deviations from HTP, it is not the only one. Other assumptions underlying HTP are steady-state behavior and incompressibility. In this paper we present new numerical simulation results that examine and quantify deviations from HTP due to compressibility for several material combinations of interest as a function of impact velocity. For these calculations all the materials are modeled as having zero strength. This is done in order to separate effects of compressibility from effects due to material strength. Some discussion of transient effects is also provided.     

Evaluation of a New Field Measurement Method for Arsenic in Drinking Water Samples

The recently lowered arsenic maximum contaminant level will require numerous U.S. water utilities and agencies to monitor and treat for arsenic. This paper describes a new method that measures arsenic in drinking water samples by generating arsine gas from the water and detecting the arsine using a paper-tape instrument. Laboratory tests indicated the method is capable of accurately detecting arsenic in water samples at the microgram per liter level (method detection limit of 0.5?μg/L and practical quantification limit of 2.5?μg/L). The only significant interferences were hydrogen sulfide and antimony. Using the paper-tape instrument, it is also possible to detect As(III) and As(V) that have been separated by either selective arsine generation or ion exchange. While the method proved accurate in the lab, difficulties were encountered during preliminary field testing on 18 different real samples. This technique of converting aqueous arsenic to arsine gas for analysis shows great promise, but the method needs to be refined for use in the field.