Thermal luminescence sensor for ground-path contamination detection

A standoff method of detecting liquids on terrestrial and synthetic landscapes is presented. The interstitial liquid layers are identified through their unique molecular vibration modes in the 7.14-14.29-microm middle infrared (fingerprint) region of liberated thermal luminescence. Several seconds of 2.45-GHz beam exposure at 1.5 W cm(-1) is sufficient for detecting polydimethyl siloxane lightly wetting the soil through its fundamental Si-CH3 and Si-O-Si stretching modes in the fingerprint region. A detection window of thermal opportunity opens as the surface attains maximum thermal gradient following irradiation by the microwave beam. The contaminant is revealed inside this window by means of a simple difference-spectrum measurement. Our goal is to reduce the time needed for optimum detection of the contaminant's thermal spectrum to a subsecond exposure from a limited intensity beam.     

A personal discriminating monitor for tritiated water vapor

A personal monitor for tritiated vapor in air based on scintillation is being developed by the Polytechnic of Milan and JRC of Ispra. A thin hygroscopic salt layer has been laid on the flat surface of a solid scintillator mounted inside the monitor. A small pump continuously supplies the monitor with filtered air samples taken from the room. The tritium oxide (HTO) in the air flow is reversibly trapped on the hygroscopic surface. A fraction of the beta particles emitted by tritium produces scintillation light in the solid scintillator which is detected by a miniaturized photomultiplier tube. The monitor can reveal HTO air contamination as low as 8×10⁵ Bq m⁻³–which is one-tenth of the limit for workers – in a short time (150 s). Several tests have been performed to check instrument response linearity and delay, the sensitivity to tritium and gamma-rays and the influence of other parameters such as air flow rate, relative humidity, vibrations and shocks.     

Thermal characteristics of water foams

As the size of foam cells increases natural convection arises and the thermal conductivity of the foam starts to grow with the foam ratio remaining constant. The factor that takes into account the effect of convection is determined.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 55, No. 2, pp. 259–265, August, 1988.     

Design of a diode-laser sensor to monitor water vapor in high-pressure combustion gases

The design of a diode-laser sensor to monitor water vapor in high-pressure combustion gases is described. The sensor, which employs a multiple-fixed-wavelength absorption strategy, has the potential to simultaneously monitor the water mole fraction and the temperature and pressure in high-pressure and high-temperature environments. The conventional scanned-wavelength strategy, employed in previous diode-laser sensors, is shown to be ill-suited for high-pressure applications. The application of impact and additive approximations in the modeling of H(2)O absorption features at high pressures is validated experimentally for number densities as high as 18 amagats. Criteria to select optimum wavelength combinations for the fixed-wavelengths strategy are discussed. Optimum wavelength combinations that meet these criteria are identified for different temperature and pressure ranges of interest to combustion applications. The proposed sensor configuration and a strategy to obtain the baseline (zero absorption intensity) in high-pressure environments are also described. Line-shape models that are appropriate for different temperature and pressure regimes are identified.     

Using principal component analysis to monitor spatial and temporal changes in water quality

Chemical, biological and physical data monitored at 12 locations along the Passaic River, New Jersey, during the year 1998 are analyzed. Principal component analysis (PCA) was used: (i) to extract the factors associated with the hydrochemistry variability; (ii) to obtain the spatial and temporal changes in the water quality. Solute content, temperature, nutrients and organics were the main patterns extracted. The spatial analysis isolated two stations showing a possible point or non-point source of pollution. This study shows the importance of environmental monitoring associated with simple but powerful statistics to better understand a complex water system.     

Thermal bonding of polymeric capillary electrophoresis microdevices in water

A new method for thermally bonding poly(methyl methacrylate) (PMMA) substrates to form microfluidic systems has been demonstrated. A PMMA substrate is first imprinted with a Si template using applied pressure and elevated temperature to form microchannel structures. This embossing method has been used to successfully pattern over 65 PMMA pieces using a single Si template. Thermal bonding for channel enclosure is accomplished by clamping together an imprinted and a blank substrate and placing the assembly in boiling water for 1 h. The functionality of these water-bonded microfluidic substrates was demonstrated by performing high-resolution electrophoretic separations of fluorescently labeled amino acids. Testing of bond strength in four microdevices showed an average failure pressure of 130 kPa, which was comparable to the bond strength for devices sealed in air. Subsequent profilometry of separated substrates revealed that the dimensions of the channels were well preserved during the bonding process. This new methodology for generation of microfluidic constructs should facilitate the permanent incorporation of hydrated, molecular size-selective membranes in microdevices, thus circumventing problems associated with membrane swelling in microfluidic systems upon exposure to water.     

Thermal conductivity of heavy-oxygen water H2O18

The ratio of thermal conductivity coefficients of heavy-oxygen water H₂O¹⁸ with different percentages of enrichment to the thermal conductivity coefficient of ordinary water is measured in the range of 0–40°C. Differences in the thermal conductivities and the temperature coefficients of the thermal conductivity of heavy-hydrogen water D₂O and and heavy-oxygen water H₂O¹⁸ are indicated.     

Thermal interaction between water flow and frozen ground under hydroerosion

A model for one of the methods of thermal reclamation of frozen ground is proposed which allows for water flow temperature variations on the ground surface due to heat exchange between the water flow and a thawing solid. In a computation experiment, the specific features of phase transition front propagation and liquid temperature variation are studied.Institute of Physicotechnical Problems of the North, North Branch of the Russian Academy of Sciences, Yakutsk, Russia. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 64, No. 2, pp. 168–171, February, 1993.     

Thermal diffusion in a turbulent water stream with gas bubbles

Results are shown of an experimental study concerning the heat transfer and the average temperature fields man effervescentgas-liquid stream. It is noted that an increase in the gas content brings about turbulent diffusion of heat across the entire stream section.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 24, No. 5, pp. 781–789, May, 1973.     

Thermal characteristics of lysine tri-isocyanate and its mixture with water

The thermal reactivity of lysine tri-isocyanate (LTI, 2-isocyanatoethyl-2,6-diisocyanato caproylate) and its mixture with 1% water was investigated after the occurrence of a runaway reaction at a plant. By using a sensitive thermal calorimeter, C80, and an adiabatic calorimeter, ARC, an onset reaction of LTI was observed at 70-100 degrees C and it became vigorous at 175-200 degrees C. The reaction is considered as co-polymerization at this stage, which causes a second decomposition reaction at 200 degrees C if the heat generation is accumulated in the vessel. On the other hand, the presence of water can catalyze LTI at much lower onset temperature and lead to a moderate reaction at 50 degrees C since carbamine is produced and in turn it induces decarbonization of the LTI molecule with significant release of CO2 gas which was detected by a gas chromatography and an FT-IR gas analyzer.     

From the grating scale monitor to the generalized seeing monitor

An instrument named the grating scale monitor for measuring the outer scale L0 from the angle-of-arrival (AA) fluctuations of a perturbed wave front was developed a few years ago at Nice University. The AA is detected with a 5-ms time resolution by modulation of the stellar image in a small telescope with a grating. One uses the normalized covariance of AA fluctuations to estimate L0. A new version of this instrument, the generalized seeing monitor (GSM) is described. It consists of four identical modules for measuring the AA at four locations on the wave front. A spatiotemporal analysis of these data leads to the determination of seeing epsilon0, outer scale L0, and the wave-front speed. In addition, isoplanatic angle theta0 is determined from scintillation, making the characterization of turbulence with the GSM almost complete. We describe the instrument and make a detailed analysis of its performance and accuracy. Several site-testing campaigns have been conducted with the GSM: at La Silla (Chile), Ouka?meden (Morocco), Maidanak (Uzbekistan), and Cerro Pachon and Cerro Paranal (Chile). The main results of these campaigns are presented and discussed.     

Hypersensitive luminescence of Eu3+ in dimethyl sulfoxide as a new probing for water measurement

Dimethyl sulfoxide (DMSO) is a well-known organic solvent that can be used for biological applications. DMSO is miscible with water, and it is very common that the two solvents are mixed for some applications. It is important to detect water in DMSO, and this has been done using the luminescence decay lifetimes from Eu(3+) ions. We observed that the emissions of Eu(3+) in DMSO are very strong and very sensitive to water. The emission band from the (5)D(0) → (7)F(2) transition has two peaks at 613 and 617 nm, respectively, and these two peaks change in the opposite ways when water is added into DMSO. The intensity ratio of the two peaks follows nearly perfect linear dependence on the water concentration added in DMSO. This linear relationship provides a new and convenient method for water measurement in DMSO.     

Capacitative dust monitor

Translated from Izmeritel'naya Tekhnika, No. 1, pp. 55–57, January, 1990.     

Press load monitor

The article describes the design and use of an instrument which displays the peak frame load during a single operating stroke of a press. It consists of a strain gauge link permanently bolted to the frame of each press to which a portable electronic unit is connected. The technique of using a strain gauge link eliminates the problems encountered when a load cell is used, or when a strain gauge system is bonded directly to the machine frame.