Kinetics of decarburisation of levitating liquid iron drops by carbon dioxide

Decarburisation experiments were carried out by levitating liquid iron droplets in a flowing gas stream containing carbon dioxide at 1723K. Decarburisation of liquid iron droplets by carbon dioxide can be adequately described by the mixed control of gas phase mass transport and dissociative chemisorption of carbon dioxide. Carbon monoxide in the gas phase does not have any significant effect on the rate of decarburisation. The rate of decarburisation decreases significantly with increase in sulphur content in the melt and this effect can be quantitatively explained using the Langmuir isotherm. Adsorption coefficient of sulphur is found to be 200. Influence of phosphorus and chromium in the melt on the rate of decarburisation is negligibly small.     

Energy as a determinant of investment behaviour

Studies of the determinants of investment behaviour have so far failed to consider the effects of changing energy prices. This paper aims to remedy this omission. After reviewing the theory of investment analysis, the author presents an econometric examination of the role of energy prices in US investment activity. He finds that the price of energy is an important factor in adequately explaining investment decisions and that its importance is likely to grow.     

Processus physicochimiques intervenant dans la preparation des membranes de diacetate de cellulose— recherche de criteres pour l'optimisation des performances I—Collodions renfermant des additifs mineraux

The fabrication of desalination membranes from cellulose acetate casting dopes containing aqueous solution of inorganic salts has been analysed by determining the water concentration required for precipitating the polymer from concentrated solutions and the time necessary for coagulation. The results enable us to correlate the water concentration to the flow rate and the coagulation time to the salt rejection.     

Topographic profiling and refractive-index analysis by use of differential interference contrast with bright-field intensity and atomic force imaging

A methodology is described for phase restoration of an object function from differential interference contrast (DIC) images. The methodology involves collecting a set of DIC images in the same plane with different bias retardation between the two illuminating light components produced by a Wollaston prism. These images, together with one conventional bright-field image, allows for reduction of the phase deconvolution restoration problem from a highly complex nonlinear mathematical formulation to a set of linear equations that can be applied to resolve the phase for images with a relatively large number of pixels. Additionally, under certain conditions, an on-line atomic force imaging system that does not interfere with the standard DIC illumination modes resolves uncertainties in large topographical variations that generally lead to a basic problem in DIC imaging, i.e., phase unwrapping. Furthermore, the availability of confocal detection allows for a three-dimensional reconstruction with high accuracy of the refractive-index measurement of the object that is to be imaged. This has been applied to reconstruction of the refractive index of an arrayed waveguide in a region in which a defect in the sample is present. The results of this paper highlight the synergism of far-field microscopies integrated with scanned probe microscopies and restoration algorithms for phase reconstruction.     

Forecasting electric utility fossil-fuel consumption

The objective of this analysis is to develop a model to forecast the consumption of fossil fuels by electric utilities on a month-to-month basis. A scheme is devised and implemented that attributes fossil-fuel generation (exclusive of coal) to the consumption of residual fuel oil, distillate fuel oil, crude oil, and natural gas. A multinomial logit specification is used whereby the share of each of these fuels is a function of relative prices, weather, time, seasonal factors, and extraneous influences (e.g. a coal strike). The results agree well with actual shares.     

Injection locking and mode selection in TEA-CO2laser oscillators

The injection of a master oscillator signal in a high-power TEA-CO2laser is analyzed and a dynamic model is formulated to represent the interaction. Based on the competition between the injected signal and the spontaneous emission, the model describes the transient evolution of the different field amplitudes and phases together with their effect on the inversion. A study over a wide range of injection levels and detuning frequencies clearly indicates three distinct regions of operation: a spontaneous oscillation zone, a mode-selection zone, and a frequency-locking zone. The main predictions of the model are compared with the results obtained with an experimental injection apparatus that assures adequate control of the TEA laser cavity length and that provides means for measuring the frequency of the output pulse. While the first two zones are directly observed, it is experimentally established that, at injection levels up to 5 W/cm², the frequency-locking zone does not exceed, as predicted, the 3-MHz resolution limit of the apparatus.     

Room temperature CW operation of GaInAsP/InP double heterostructure diode lasers emitting at 1.5 ?m grown by low pressure metalorganic chemical vapour deposition (LP-MO CVD)

Room temperature continuous wave (CW) operation at 1.5 ?m has been achieved in GaInAsP/InP DH lasers fabricated on material grown by low-pressure metalorganic chemical vapour deposition (LP-MO CVD). Threshold currents as low as 200 mA DC have been measured for devices with a stripe width of 9 ?m and a cavity length of 300 ?m. Values of To as high as 64 K have been obtained, where To is defined by the expression Jth(T) = Jth(0) exp (T/To). Fundamental transverse mode oscillation has been achieved up to an output power of 10 mW.     

Matched-pair cohort methods in traffic crash research

Standard analysis of matched-pair cohort data requires information only from pairs in which at least one had the study outcome. This can be useful in traffic fatality studies of characteristics that can vary among vehicle occupants, such as seat belt use, as crash databases often lack information about vehicles in which all survived. However, matching crash victims who were in the same vehicle does not necessarily eliminate confounding by vehicle or crash related factors, because the matched occupants must be in different seat positions. This paper reviews three methods for estimating relative risks in matched-pair crash data. The first, Mantel-Haenszel stratified methods, may produce biased estimates if seat position is associated with the outcome. The second, the double-pair comparison method, was designed to deal with confounding by seat position. If the effects of seat position vary according to some vehicle or crash characteristic which is associated with the study exposure, adjustment for this characteristic may be needed to produce unbiased estimates. Third, conditional Poisson regression and Cox proportional hazards regression can produce unbiased estimates, but may require model interaction terms between seat position and vehicle or crash characteristics. This paper reviews some of the strengths and limitations of each of these methods, and illustrates their use in simulated and real crash data.