ADVANTAGES AND USE OF A CO2 METER ON A FORCED DOWNDRAFT PERIODIC KILN AS TO TEMPERATURE DISTRIBUTION1

Notes on forced downdraft system used on dry-pressed electrical porcelain fired to cone 12 flat are discussed. The type and general construction of the kiln, heat distribution, fuel used per firing, and the use of the CO₂ meter for adjusting the draft for various conditions to get uniformly fired kilns, both as to time of firing and appearance of ware, are given.     

Nitric oxide mediates sexual behavior in female rats

Nitric oxide (NO), an active free radical formed during the conversion of arginine to citrulline by the enzyme NO synthase (NOS), mediates vasorelaxation, cytotoxicity, and neurotransmission. Neurons containing NOS (NOergic) are located in the hypothalamus. These NOergic neurons control the release of several hypothalamic peptides. Release of NO from these NOergic neurons stimulates pulsatile release of luteinizing hormone-releasing hormone (LHRH) in vivo and LHRH release in vitro. LHRH not only induces LH release, which induces ovulation, but also facilitates female sexual behavior. Sexual behavior can be induced reliably in estrogen-primed ovariectomized female rats by progesterone (P). This behavior consists of proceptive behavior to attract the male and the assumption of a clear characteristic posture, lordosis, when mounted by the male. To ascertain the role of NO in the control of sexual behavior in female rats, an inhibitor of NOS, NG-monomethyl-L-arginine was microinjected into the third cerebral ventricle (3V) of conscious, ovariectomized, estrogen-primed rats with indwelling cannulae. NG-Monomethyl-L-arginine (10-1000 micrograms) prevented P-facilitated lordosis when administered intracerebroventricularly into the 3V, 20 min prior to the 3V injection of P. NG-Monomethyl-D-arginine, which does not inhibit NOS, did not inhibit lordosis under the same experimental conditions. Microinjection into the 3V of sodium nitroprusside (SNP), which spontaneously releases NO, facilitated lordosis in estrogen-primed rats in the absence of P. The facilitation of lordosis induced by either P or SNP was prevented by intracerebroventricular injection of hemoglobin, which binds NO. Lordosis facilitated by P or SNP was blocked by injection of LHRH antiserum into the 3V. The results are interpreted to mean that the P-facilitated lordosis response is mediated by LHRH release. Furthermore, since NO release from SNP also facilitates lordosis in the absence of P and this response could be blocked by LHRH antiserum, we conclude that P brings about the release of NO, which stimulates LHRH release that facilitates lordosis. Thus, the results indicate that NO induces LHRH release and that LHRH then plays a crucial role in mediation of sexual behavior in the female rats.     

Fiber-based UV laser-diode fluorescence sensor for commercial gasolines

We report on an optical fiber probe, coupled to a 404-nm laser diode, as a fluorescence sensor for monitoring of commercial gasolines. The principle of operation of the sensor is based on quantifying the intensity of the Stokes-shifted fluorescence from some of the heavier polycyclic aromatic hydrocarbons C/sub x/H/sub y/,(x,y) /spl ges/ (14,10) present in gasolines as minor constituents. The normalized efficiency of the optical fiber probe, as a function of its geometry, is calculated in the cases of single-fiber and parallel dual-fiber designs. The spatial and temporal resolutions achievable by the sensor are discussed as a function of design parameters The performance of the sensor is investigated experimentally for commercial gasolines in the liquid and gas phase. The optimal excitation wavelength for such sensors is investigated in the range of 350-400 nm. The linear sensitivity to vapor concentrations of retail gasoline fuel is demonstrated in the range of 4%-125% of combustion stoichiometry at 10 bar and 180/spl deg/C. Statistical processing of the data from the sensor allows distinction to be made between different forecourt gasoline suppliers, as well as fuel varieties (unleaded, low sulfur, etc.).     

Diet preference in rats (Rattus norvegicus) as a function of odor exposure, odor concentration, and conspecific presence.

The relative contributions of social and stimulus factors in development of rat dietary preferences were examined. Investigation of odor-alone effects revealed that weak odors resulted in preference for familiar-odor diets, but only at longer exposure times. Shorter exposure to strong odors also produced differences in diet preference. When odor and conspecific presence were manipulated simultaneously, odors produced no diet preference at low intensities, whereas high-intensity odors did so regardless of conspecific presence. Medium-intensity odor concentrations produced differences only with conspecifics present, indicating social enhancement of stimuli that are ineffective in isolation. These results suggest the separate influence of social and stimulus factors on dietary preferences and explain contradictions in previous studies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Experimental verifications of numerical predictions for the hydrodynamic performance of horizontal axis marine current turbines

The conversion of the kinetic energy presented by ocean or marine currents offers an exciting proposition as it can provide regular and predictable energy resource. The majority of the proposed designs for converting this type of kinetic energy are based on the concept of the horizontal axis turbines, which has common characteristics to those being used in wind energy. Although a lot can be learnt and transferred from wind turbine technology, there are significant differences. These include the effects of the free surface and the occurrence of cavitation. Consequently, any developed numerical methods need to be verified. This study reports on the development and verification of simulation tools based on blade element momentum theory—a commercial code (GH-Tidal Bladed) and an academic in-house code (SERG-Tidal). Validation is derived from experimental measurements conducted on a model 800 mm diameter turbine in a cavitation tunnel and a towing tank. The experimental data includes measurements of shaft power and thrust generated by the turbine for a series of blade pitch settings and speeds. The results derived from the two codes are compared. These indicate that the two developed codes demonstrate similar trends in the results and provide a satisfactory representation of the experimental turbine performance. Such results give the necessary confidence in the developed codes resulting in appropriate tools that can to be utilised by developers of marine current turbines.     

Full day simulations of anti-reflection coatings for flat plate silicon photovoltaics

This paper presents an investigation into the use of thin films of silicon oxide and silicon nitride as anti-reflection coatings to minimise the reflection losses of incident solar insolation on silicon photovoltaic cells. The total theoretical reflectance under two insolation cases is investigated. Firstly, with AM 1.5 direct beam radiation at normal incidence, as is usually simulated, and secondly, with the direct beam simulated over a full day. Ensuring that a minimum silicon oxide layer of 20 nm is deposited on the silicon wafer for surface passivation, variations in optimised film thicknesses between both simulations were approximately 4%. The theoretical results also showed a strong correlation to experimental results for the normal incident case. The results demonstrate that surfaces optimised for normally incident radiation are adequate for non-tracking photovoltaic cells under real conditions. The seasonal variations of an optimised surface showed variations in a performance of less than 0.1%. We have also demonstrated that the excellent surface passivation obtained with a thin thermal oxide is maintained after depositing a silicon nitride layer using low-pressure chemical vapour deposition.     

Lower bound earthquake magnitude for probabilistic seismic hazard evaluation

This paper presents the results of a study that develops an engineering and seismological basis for selecting a lower-bound magnitude (LBM) for use in seismic hazard assessment. As part of a seismic hazard analysis the range of earthquake magnitudes that are included in the assessment of the probability of exceedance of ground motion must be defined. The upper-bound magnitude is established by earth science experts based on their interpretation of the maximum size of earthquakes that can be generated by a seismic source. The lower-bound or smallest earthquake that is considered in the analysis must also be specified.The LBM limits the earthquakes that are considered in assessing the probability that specified ground motion levels are exceeded. In the past there has not been a direct consideration of the appropriate LBM value that should be used in a seismic hazard assessment. This study specifically looks at the selection of a LBM for use in seismic hazard analyses that are input to the evaluation/design of nuclear power plants (NPPs). Topics addressed in the evaluation of a LBM are earthquake experience data at heavy industrial facilities, engineering characteristics of ground motions associated with small-magnitude earthquakes, probabilistic seismic risk assessments (seismic PRAs), and seismic margin evaluations. The results of this study and the recommendations concerning a LBM for use in seismic hazard assessments are discussed.     

Adaptive calibration of a capacitance tomography system for imaging water droplet distribution

A highly sensitive electrical capacitance tomography (ECT) system based on an HP4284 impedance analyser has been developed and used to quantify low concentration multi-phase flows in wet gas separation processes. The system hardware provides high accuracy (0.05%) and high resolution (10⁻¹⁷ F). The sensor was calibrated in an environmental chamber with solid samples of known permittivity over ranges of temperature and humidity. Adaptive calibration and adjacent electrode pair correction techniques were applied to image very low concentration profiles. This paper describes the techniques used and presents the experimental results obtained from a test flow rig called Twister, which has been designed to separate liquid droplets from wet gas streams. The test results over a range of operating conditions (20–95% humidity) demonstrate that the ECT system is capable of reconstructing clear images of the droplet distribution inside Twister. Changes as small as 1 gWater/kgAir in the form of liquid droplets were detectable. It has also been shown that the concentration of the condensable phase can be estimated quantitatively within 20% in comparison with the reference measurements.