Sample records for constantan

  1. 16 CFR 1505.6 - Performance.

    Code of Federal Regulations, 2014 CFR


    ... flat-iron, a cooking surface, or a heating element surface), or (b) a material heated by the element... the shelf pack or package as being intended only for children over 12 years of age provided that the... Gage) wire (either copper and constantan or iron and constantan) and potentiometer-type...

  2. 16 CFR 1505.6 - Performance.

    Code of Federal Regulations, 2013 CFR


    ... flat-iron, a cooking surface, or a heating element surface), or (b) a material heated by the element... the shelf pack or package as being intended only for children over 12 years of age provided that the... Gage) wire (either copper and constantan or iron and constantan) and potentiometer-type...

  3. High-Sensitivity Temperature Measurement

    ERIC Educational Resources Information Center

    Leadstone, G. S.


    Describes a method of measuring small temperature differences that amount to a .01K, using an arrangement of a copper-constantan thermocouple, a microamplifier and a galvanometer, as an indirect way of measuring heat energy. (GA)

  4. Pressure measurements of nonplanar stress waves

    SciTech Connect

    Carlson, G.H.; Charest, J.A.


    Measuring the pressure of non-planar stress waves using thin piezo-resistive gages requires correcting for induced strain parallel to the sensing elements. A technique has been developed that permits such measurements, making use of a dual element gage. One element, Manganin, is sensitive to stress both parallel and perpendicular to the sensing element; the other element, Constantan, is primarily sensitive to stress parallel to the sensing element. The change in resistance in the Constantan element is thereby used to correct for the strain effect parallel to the Manganin element axis. Individual and combined Manganin and Constantan elements were subjected to controlled gas gun impact tests in the pressure and strain ranges of 0 to 50 kbar and 0 to 7%, respectively. From planar wave tests, the piezoresistivity of Constantan was found to be positive but negligible in comparison with Manganin. From combined stress and strain environments, the compression and tension strain factors of Constantan were found to be constant and equal to 2.06. The strain factors of Manganin were found to increase from 1.2 to 2.0 asymptotically in the range of 0 to 3% strain. It was experimentally demonstrated that, because of the closeness of their strain factors, the Manganin-Constantan dual element gage could be used in the differential recording mode to yield pressure directly. In this mode the gage is a strain compensating gage. Analytical techniques have also been developed for more accurate strain compensation.

  5. A thermocouple thermode for small animals

    NASA Technical Reports Server (NTRS)

    Williams, B. A.


    Thermode composed of two thin-walled stainless steel hypodermic needles and cooper-constantan thermocouple or small thermistor to indicate temperature at point of perfusion is used to measure brain temperature in animals. Because of relatively small size of thermode, structural damage to brain is minimized.

  6. Modern Thermocouple Experiment.

    ERIC Educational Resources Information Center

    Chang, K. N.; And Others


    Describes a thermocouple circuit used to measure Joule heating as well as Peltier heating and cooling for a copper-Constantan metallic junction. Shows how the Seebeck effect from a thermocouple can monitor the temperature condition of a junction with regard to input power and Peltier effect. (Author/GA)


    EPA Science Inventory

    An electronic circuit has been developed which acts as an electronic ice bath for chromel-constantan thermocouples. The electronic ice bath is accurate to within plus or minus 0.2C from -25C to +50C. Simultaneously, the thermocouple output is scaled and linearized such that the t...

  8. Observations of long delays to detonation in propellant for tests with marginal card gaps

    NASA Technical Reports Server (NTRS)

    Olinger, B.


    Using the large-scale card gap tests with pin and high-speed framing camera techniques, VRP propellant, and presumably others, were found to transit to detonation at marginal gaps after a long delay. In addition, manganin-constantan gauge measurements were made in the card gap stack.

  9. Pressure measurement in a recovery tube for superhard BN synthesized by explosion

    SciTech Connect

    Yun, S.R.; Huang, Z.P.; Shun, Y.F.


    Double {pi}-form gauge pair made of the manganin foil and the constantan foil, with the sensing element being 0.6mm long and 0.15mm wide, is carefully embeded in the different radius R interior BN in the recovery tube. The digitizing oscilloscope TEK 2430A is used for recording the gauge output signals supported by the constant current pulsed-power supply. The pure pressure analogue signals involved in the manganin gauge records are acquired by that the records minus the pure tensile analogue signals involved in constantan gauge records, then the pressure P can be worked out by the use of dynamic piezoresistance function and the tensile coefficient according to the above clue the P-R correlation interior BN in the recovery tube, corresponding to the different explosion-load condition, is measured and the phase transition condition of BN is also given. {copyright} {ital 1996 American Institute of Physics.}

  10. A Miniature Stem Thermocouple Hygrometer 1

    PubMed Central

    Michel, Burlyn E.


    An unprotected chromel-constantan thermocouple was mounted in a cavity (4 × 2 × 1 mm) with rounded corners in a chrome-plated brass block (10 × 6 × 4 mm). When installed against a soybean (Glycine max [L.] Merr.) xylem face, sealed with caulking gum, and insulated with polyurethane foam and aluminum foil, even rapidly changing stem water potentials could be followed accurately. Temperature gradients can be a problem. PMID:16660155

  11. Temperature kinetics during shock-wave consolidation of metallic powders

    SciTech Connect

    Schwarz, R.B.; Kasiraj, P.; Vreeland, T. Jr.


    Powders (60 diam) of constantan and pure copper were compressed statically into cylindrical greens (20.3 mm diam, 5.3 mm long) with a flat interface separating the two powders. A 20-mm propellant gun was used to accelerate a flyer of Lexan, copper, or aluminum, and generate in the green a shock wave with front parallel to the Cu/constantan interface. The voltages between opposite ends of the greens were measured as a function of time and for shock pressures between 1.3 and 9.4 GPa. When the shock wave arrives at the Cu/constantan interface, the voltage signal shows an abrupt increase, which lasts between 45 and 81 ns and leads to a peak temperature T/sub p/. After this, the hotter and cooler parts of the compact equilibrate and the temperature decreases to a value T/sub h/. With increasing shock pressure, T/sub h/ increases from 425 to 1215 K. The measurements of T/sub h/ are in excellent agreement with the temperatures calculated from the measured flyer velocity, the Hugoniot for copper powder, and thermodynamic data for the flyer and powders.

  12. Triple-material stress-strain resistivity gage


    Stout, R.B.


    A triple material piezoresistive gage provides multi-component elastic stress measurements is disclosed. Thin foils of three piezoresistive materials, e.g. ytterbium, manganin, and constantan, are configured in a nested serpentine rectilinear grid or other grid arrangement and embedded in a medium, preferably normal to the direction of shock wave propagation. The output of the gage is a resistivity change history for each material of the gage. Each resistivity change is independent of the others so that three diagonal components of the elastic stress or strain tensor can be calculated from the resistivity measurements. 4 figs.

  13. Triple-material stress-strain resistivity gage


    Stout, R.B.


    A triple material piezoresistive gage provides multi-component elastic stress or strain measurements. Thin foils of three piezoresistive materials, e.g., ytterbium, manganin, and constantan, are configured in a nested serpentine rectilinear grind or other grind arrangement and embedded in a medium, preferably normal to the direction of shock wave propagation. The output of the gage is a resistivity change history for each material of gage. Each resistivity change is independent of the others so that three diagonal components of the elastic stress or strain tensor can be calculated form the resistivity measurements. 4 figs.

  14. Triple-material stress-strain resistivity gage


    Stout, Ray B.


    A triple material piezoresistive gage provides multi-component elastic stress or measurements. Thin foils of three piezoresistive materials, e.g. ytterbium, manganin, and constantan, are configured in a nested serpentine rectilinear grid or other grid arrangement and embedded in a medium, preferably normal to the direction of shock wave propagation. The output of the gage is a resistivity change history for each material of the gage. Each resistivity change is independent of the others so that three diagonal components of the elastic stress or strain tensor can be calculated from the resistivity measurements.

  15. Heat transfer tests of a 0.006-scale thin skin space shuttle model (50-0, 41-T) in the Langley Research Center nitrogen tunnel at Mach 19 (IH19)

    NASA Technical Reports Server (NTRS)

    Walstad, D. G.


    Data are presented from heat transfer tests on an 0.0006-scale space shuttle vehicle in the Langley Research Center Nitrogen Tunnel. The purpose of this test was to obtain ascent heating data at a high hypersonic Mach number. Configurations tested were integrated orbiter and external tank, orbiter alone, and external tank alone. All configurations were tested with and without boundary layer transition. Testing was conducted at a Mach number of 19, a Reynolds number of 0.5 million per foot, and angles of attack of 0, + or - 5, and + or - 10 degrees. Heat transfer data was obtained from 77 orbiter and 90 external tank iron-constantan thermocouples.

  16. Theory and performance of plated thermocouples.

    NASA Technical Reports Server (NTRS)

    Pesko, R. N.; Ash, R. L.; Cupschalk, S. G.; Germain, E. F.


    A theory has been developed to describe the performance of thermocouples which have been formed by electroplating portions of one thermoelectric material with another. The electroplated leg of the thermocouple was modeled as a collection of infinitesimally small homogeneous thermocouples connected in series. Experiments were performed using several combinations of Constantan wire sizes and copper plating thicknesses. A transient method was used to develop the thermoelectric calibrations, and the theory was found to be in quite good agreement with the experiments. In addition, data gathered in a Soviet experiment were also found to be in close agreement with the theory.

  17. Black coatings for stray light and thermal control applications

    NASA Astrophysics Data System (ADS)

    Moldosanov, Kamil A.; Kashirin, Victor A.; Skrynnikov, Alexander M.; Anisimova, Irina A.; Anisimov, Vladimir P.; Kobtsov, Gennady A.


    This report deals with comparison of the total hemispherical reflectances (THR), emissivities, and solar radiation absorption factors of coatings designed to reduce a stray light background and provide the thermal control both in space-based instruments and in land-based equipment. The THR measurement results are presented that have been carried out at 10 values of wavelengths within visible, near- ultraviolet, and near-infrared ranges (400 to 927 nm). The coatings being compared are as follows: chemically oxidized copper, coating on the basis of Al-N system, black-chromium coating, black bituminous paint, commercial black enamel used in solar converters, and plasmatron sputtered nichrome and constantan alloys. The chemically oxidized copper has been chosen as a material possessing high solar radiation absorption factor and low emissivity. Black-chromium coating is a widespread material for thermal control in space instruments. The black bituminous paint has been chosen as a possible cheap alternative solar absorber. Commercial black enamel served as a standard conventional coating used in some inexpensive solar converters. Nichrome and constantan have been also selected for investigations as the alloys having high specific resistivities, which promised that intensive electron scattering in skin layers of these alloys could take place, i.e., intensive transfer of energy and momentum received from the light wave to the lattice.

  18. Developments in convective heat transfer models featuring seamless and selected detail surfaces, employing electroless plating

    NASA Technical Reports Server (NTRS)

    Stalmach, C. J., Jr.


    Several model/instrument concepts employing electroless metallic skin were considered for improvement of surface condition, accuracy, and cost of contoured-geometry convective heat transfer models. A plated semi-infinite slab approach was chosen for development and evaluation in a hypersonic wind tunnel. The plated slab model consists of an epoxy casting containing fine constantan wires accurately placed at specified surface locations. An electroless alloy was deposited on the plastic surface that provides a hard, uniformly thick, seamless skin. The chosen alloy forms a high-output thermocouple junction with each exposed constantan wire, providing means of determining heat transfer during tunnel testing of the model. A selective electroless plating procedure was used to deposit scaled heatshield tiles on the lower surface of a 0.0175-scale shuttle orbiter model. Twenty-five percent of the tiles were randomly selected and plated to a height of 0.001-inch. The purpose was to assess the heating effects of surface roughness simulating misalignment of tiles that may occur during manufacture of the spacecraft.

  19. A redetermination of the succinonitrile-water phase diagram

    NASA Technical Reports Server (NTRS)

    Smith, J. E., Jr.; Frazier, D. O.; Kaukler, W. F.


    The phase diagram of the water/succinonitrile system often used in modeling binary metallic alloys is determined experimentally using a laser scattering method. Triply distilled and zone-refined succinonitrile is placed in a jacketed water-cooled vessel with a magnetic mixer and a copper-constantan thermocouple, and the melting point is determined under vacuum and under Ar by observing the response of a photodiode placed opposite a laser source as the chamber is cooled and reheated. Then water is added, and the eutectic and monotectic temperatures and the entire phase diagram are determined under Ar. The results are presented in a table and graph and compared to those of Schreinemakers (1897): significant discrepancies are noted and attributed to impurities in the succinonitrile used by Schreinemakers. The importance of accurate phase diagrams for modeling binary alloys is stressed.

  20. BOREAS TE-6 1994 Soil and Air Temperatures in the NSA

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Norman, John; Wilson, Tim


    The BOREAS TE-6 team collected several data sets to examine the influence of vegetation, climate, and their interactions on the major carbon fluxes for boreal forest species. This data set contains measurements of the air temperature at a single height and soil temperature at several depths in the NSA from 25-May to 08-Oct- 1994. Chromel-Constantan thermocouple wires run by a miniprogrammable data logger (Model 21X, Campbell Scientific, Inc., Logan, UT) provided direct measurements of temperature. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distrobuted Activity Archive Center (DAAC).

  1. A coaxial thermocouple for shock tunnel applications.


    Menezes, Viren; Bhat, Sandeep


    A chromel-constantan coaxial surface junction thermocouple has been designed, fabricated, calibrated, and tested to measure the temperature-time history on the surface of a body in a hypersonic freestream of Mach 8 in a shock tunnel. The coaxial thermocouple with a diameter of 3.25 mm was flush mounted in the surface of a hemisphere of 25 mm diameter. The hypersonic freestream was of a very low temperature and density, and had a flow time of about a millisecond. Preliminary test results indicate that the thermocouple is quite sensitive to low temperature-rarefied freestreams, and also has a response time of a few microseconds (≈5 μs) to meet the requirements of short duration transient measurements. The sensor developed is accurate, robust, reproducible, and is highly inexpensive. PMID:21034112

  2. Resistance temperature detective materials as the thermo power generator elements

    NASA Astrophysics Data System (ADS)

    Singh, Jaspal; Verma, S. S.


    The conventional RTD (Resistance Temperature Detective) thermocouples of types B, E, R, K and S are the efficient keys in the temperature sensing applications. These are the combinations of thermoelectric materials like Platinum, Rhodium, Constantan, Chromel, and Alumel which works on the Seebeck theory. The chief objective of this research work is only to explore their energy conversion efficiencies in the temperature range of 330°C by the generations of thermo emf. The present research work is carried out in the two parts; one is for the normal conditions and the other for the applied magnetic field of three different magnitudes i.e. 260Gauss, 360Gauss and 460Gauss. Hence this paper reports about the energy management aspects of RTD materials not only by the direct conversion of heat into electricity but also along with the magnetic field.

  3. Heat transfer tests of an 0.006-scale thin-skin space shuttle model (41-OTS) in the Ames 3.5-foot HWT at M equals 5.3 (IH15)

    NASA Technical Reports Server (NTRS)

    Walstad, D. G.; Lockman, W. K.


    Data obtained from heat transfer tests of an 0.006-scale space shuttle vehicle in a 3.5-foot hypersonic wind tunnel are presented. The purpose of these tests was to parametrically investigate the ascent heating of the integrated vehicle. Configurations tested were complete for integrated vehicle, orbiter alone, external tank alone, and SRB alone. All configurations were tested with and without transition grit. Testing was conducted at a Mach number of 5.3, and at Reynolds numbers of 2 and 5 million per foot. The angle of attack range varied from 0 to minus 5 degress, execpt for SRB alone, which was tested from minus 5 to 90 degrees. Heat transfer data were obtained from 223 iron-constantan thermocouples attached to thin-skin stainless steel inserts.

  4. Heat transfer test of an 0.006-scale thin-skin thermocouple space shuttle model (50-0, 41-T) in the NASA-Ames Research Center 3.5-foot hypersonic wind tunnel at Mach 5.3 (IH28), volume 1

    NASA Technical Reports Server (NTRS)

    Cummings, J. W.; Foster, T. F.; Lockman, W. K.


    Data obtained from a heat transfer test conducted on an 0.006-scale space shuttle orbiter and external tank in the NASA-Ames Research Center 3.5-foot Hypersonic Wind Tunnel are presented. The purpose of this test was to obtain data under simulated return-to-launch-site abort conditions. Configurations tested were integrated orbiter and external tank, orbiter alone, and external tank alone at angles of attack of 0, + or - 30, + or - 60, + or - 90, and + or - 120 degrees. Runs were conducted at Mach numbers of 5.2 and 5.3 for Reynolds numbers of 1.0 and 4.0 million per foot, respectively. Heat transfer data were obtained from 75 orbiter and 75 external tank iron-constantan thermocouples.

  5. Statistical Analysis of a Round-Robin Measurement Survey of Two Candidate Materials for a Seebeck Coefficient Standard Reference Material

    PubMed Central

    Lu, Z. Q. J.; Lowhorn, N. D.; Wong-Ng, W.; Zhang, W.; Thomas, E. L.; Otani, M.; Green, M. L.; Tran, T. N.; Caylor, C.; Dilley, N. R.; Downey, A.; Edwards, B.; Elsner, N.; Ghamaty, S.; Hogan, T.; Jie, Q.; Li, Q.; Martin, J.; Nolas, G.; Obara, H.; Sharp, J.; Venkatasubramanian, R.; Willigan, R.; Yang, J.; Tritt, T.


    In an effort to develop a Standard Reference Material (SRM™) for Seebeck coefficient, we have conducted a round-robin measurement survey of two candidate materials—undoped Bi2Te3 and Constantan (55 % Cu and 45 % Ni alloy). Measurements were performed in two rounds by twelve laboratories involved in active thermoelectric research using a number of different commercial and custom-built measurement systems and techniques. In this paper we report the detailed statistical analyses on the interlaboratory measurement results and the statistical methodology for analysis of irregularly sampled measurement curves in the interlaboratory study setting. Based on these results, we have selected Bi2Te3 as the prototype standard material. Once available, this SRM will be useful for future interlaboratory data comparison and instrument calibrations.

  6. Note: A sample holder design for sensitive magnetic measurements at high temperatures in a magnetic properties measurement system

    SciTech Connect

    Arauzo, A.; Guerrero, E.; Urtizberea, A.; Stankiewicz, J.; Rillo, C.


    A sample holder design for high temperature measurements in a commercial MPMS SQUID magnetometer from Quantum Design is presented. It fulfills the requirements for the simultaneous use of the oven and reciprocating sample option (RSO) options, thus allowing sensitive magnetic measurements up to 800 K. Alternating current susceptibility can also be measured, since the holder does not induce any phase shift relative to the ac driven field. It is easily fabricated by twisting Constantan Copyright-Sign wires into a braid nesting the sample inside. This design ensures that the sample be placed tightly into a tough holder with its orientation fixed, and prevents any sample displacement during the fast movements of the RSO transport, up to high temperatures.

  7. Heat transfer tests of an 0.006-scale thin-skin space shuttle thermocouple model (41-OTS) in the Langley Research Center unitary plan wind tunnel at M equals 3.7 (IH16)

    NASA Technical Reports Server (NTRS)

    Walstad, D. G.


    The results are presented of supersonic heat transfer tests performed on the .006 scale space shuttle vehicle model (41-OTS) in the Langley Research Center Unitary Plan Wind Tunnel. These tests were conducted to parametrically investigate ascent heating of the integrated vehicle and its components. The tests were conducted at a nominal Mach number of 3.7 and Reynolds numbers per foot of 2 and 5 million. The model configurations investigated were the integrated vehicle and each component alone (i.e. orbiter, tank and SRB). All the configurations were run with and without transition strips and through an angle of attack range of 0 deg to minus 5 deg with the exception of the SRB which was tested through an angle of attack range of minus 5 deg to 90 deg. The heat transfer data were obtained from 223 iron constantan thermocouples attached to stainless steel thin-skin areas of the model.

  8. Surface Catalysis and Oxidation on Stagnation Point Heat Flux Measurements in High Enthalpy Arc Jets

    NASA Technical Reports Server (NTRS)

    Nawaz, Anuscheh; Driver, David M.; Terrazas-Salinas


    Heat flux sensors are routinely used in arc jet facilities to determine heat transfer rates from plasma plume. The goal of this study is to assess the impact of surface composition changes on these heat flux sensors. Surface compositions can change due to oxidation and material deposition from the arc jet. Systematic surface analyses of the sensors were conducted before and after exposure to plasma. Currently copper is commonly used as surface material. Other surface materials were studied including nickel, constantan gold, platinum and silicon dioxide. The surfaces were exposed to plasma between 0.3 seconds and 3 seconds. Surface changes due to oxidation as well as copper deposition from the arc jets were observed. Results from changes in measured heat flux as a function of surface catalycity is given, along with a first assessment of enthalpy for these measurements. The use of cupric oxide is recommended for future heat flux measurements, due to its consistent surface composition arc jets.

  9. Evaluation of measurement errors of temperature and relative humidity from HOBO data logger under different conditions of exposure to solar radiation.


    da Cunha, Antonio Ribeiro


    This study aimed to assess measurements of temperature and relative humidity obtained with HOBO a data logger, under various conditions of exposure to solar radiation, comparing them with those obtained through the use of a temperature/relative humidity probe and a copper-constantan thermocouple psychrometer, which are considered the standards for obtaining such measurements. Data were collected over a 6-day period (from 25 March to 1 April, 2010), during which the equipment was monitored continuously and simultaneously. We employed the following combinations of equipment and conditions: a HOBO data logger in full sunlight; a HOBO data logger shielded within a white plastic cup with windows for air circulation; a HOBO data logger shielded within a gill-type shelter (multi-plate prototype plastic); a copper-constantan thermocouple psychrometer exposed to natural ventilation and protected from sunlight; and a temperature/relative humidity probe under a commercial, multi-plate radiation shield. Comparisons between the measurements obtained with the various devices were made on the basis of statistical indicators: linear regression, with coefficient of determination; index of agreement; maximum absolute error; and mean absolute error. The prototype multi-plate shelter (gill-type) used in order to protect the HOBO data logger was found to provide the best protection against the effects of solar radiation on measurements of temperature and relative humidity. The precision and accuracy of a device that measures temperature and relative humidity depend on an efficient shelter that minimizes the interference caused by solar radiation, thereby avoiding erroneous analysis of the data obtained. PMID:25855203

  10. Performance of a small, low-lift regenerator-based thermoacoustic refrigerator

    NASA Astrophysics Data System (ADS)

    Poese, Matthew E.; Garrett, Steven L.


    A regenerator-based thermoacoustic refrigerator [Swift, Gardner, and Backhaus, ''Acoustic recovery of lost power in pulse tube refrigerators,'' J. Acoust. Soc. Am. 105(2), 711 (1999)] has been constructed. It is capable of moving about 5 W across a 40degC temperature span. The machine operates with air at atmospheric pressure and is driven by an off-the-shelf electro-dynamic loudspeaker capable of producing peak-to-mean pressure ratios up to 12%. The thermal core of this research device contains an exhaust-side shell and tube heat exchanger (with water as the secondary heat transfer fluid), a regenerator made of 88 annular stainless-steel screens, and a constantan wire electrical heater that applies a measurable heat load to the cold side of the regenerator. An annular latex diaphragm is placed over the cold side of the regenerator to stop time-averaged mass flow through the regenerator and insulate the cold side [Gedeon, ''DC Gas Flows in Stirling and Pulse Tube Cryocoolers,'' in Cryocoolers 9, edited by R. G. Ross (Plenum, New York, 1997)]. Detailed measurements of heat load, temperature span, and exhaust heat flux will be presented and compared to DeltaE. [Work supported by ONR.

  11. Rocket engine hot-spot detector

    NASA Astrophysics Data System (ADS)

    Collamore, F. N.


    On high performance devices such as rocket engines it is desirable to know if local hot spots or areas of reduced cooling margin exist. The objective of this program is to design, fabricate and test an electronic hot spot detector capable of sensing local hot spot on the exterior circumference of a regeneratively cooled combustion chamber in order to avoid hardware damage. The electronic hot spot sensor consists of an array of 120 thermocouple elements which are bonded in a flexible belt of polyimide film. The design temperature range is from +30 F to +400 F continuously with an intermittent temperature of 500 F maximum. The thermocouple belt consists of 120 equally spaced copper-Constantan thermocouple junctions which is wrapped around the OMS liquid rocket engine combustion chamber, to monitor temperatures of individual cooling channels. Each thermocouple is located over a cooling channel near the injector end of the combustion chamber. The thermocouple array sensor is held in place by a spring loaded clamp band. Analyses show that in the event of a blocked cooling channel the surface temperature of the chamber over the blocked channel will rise from a normal operating temperature of approx. 300 F to approx. 600 F. The hot spot detector will respond quickly to this change with a response time constant less than 0.05 seconds. The hot spot sensor assembly is fabricated with a laminated construction of layers of Kapton film and an outer protective layer of fiberglass reinforced silicone rubber.

  12. Natural convection immersion cooling of an array of vertically oriented heated protrusions in an enclosure filled with a dielectric liquid: Effects of enclosure width, Prandtl number and component orientation

    NASA Astrophysics Data System (ADS)

    Matthews, Scott T.


    The natural convection heat transfer characteristics of a 3 x 3 array of vertically oriented heated protrusions, immersed in a dielectric liquid, were investigated. Aluminum blocks, 24 x 8 x 6 mm, were used to simulate 20 pin dual in-line packages. Surface temperature measurements of the components were made by imbedding copper-constantan thermocouples below the surface of each component face. A constant heat flux was provided to each component using an Inconel foil heating element. Power supplied to each component varied from 0.115 to 2.90 W. The aluminum blocks were mounted on a plexiglass substrate to form a 3 x 3 array of simulated electronic components. The circuit board containing the components was placed in a rectangular, plexiglass enclosure with inner dimensions: L = 203.2 mm H = 152.0 mm W = 82.6 mm, and a wall thickness of 25.4 mm. The upper boundary was maintained at 10 C, while all other exterior surfaces were insulated. The chamber width, measured from the surface of the circuit board to the opposite, inner wall of the enclosure, was varied from 42 to 7 mm by inserting plexiglass spacers into the enclosure. Two dielectric liquids, FC-75 and FC-43, were used as working fluids. Nondimensional data from this study was combined with the data obtained for a horizontal component orientation, to develop an empirical correlation which predicts the Nusselt number as a function of Rayleigh number, Prandtl number, component orientation, and chamber width.

  13. Developments in strong shock wave position tracking

    NASA Astrophysics Data System (ADS)

    Rae, Philip; Glover, Brain; Perry, Lee; WX-6; WX-7 Team


    This poster will highlight several modified techniques to allow the position vs. time to be tracked in strong shock situations (such as detonation). Each is a modification or improvement of existing ideas either making use of advances in specialist materials availability or recent advances in electronics.) Shorting embedded mini-coaxial cable with a standing microwave pattern. This technique is a modified version of an old LANL method of shock position tracking making use of a traveling short imposed in an embedded coaxial cable. A high frequency standing wave (3-8GHz) is present in the cable and the moving short position can be tracked by monitoring the output voltage envelope as a function of time. A diode detector is used to allow the envelope voltage to be monitored on a regular low frequency digitizer significantly reducing the cost. The small and cheap high frequency voltage generators now available allow much greater spatial resolution than possible previously. 2) Very thin shorting resistance track gauges. Parallel tracks of constantan resistance material are etched on a thin dielectric substrate. The gauges are less than 0.2 mm thick. The ionized gas present in a detonation front sweeps up the tracks lowering the measured resistance. A potential divider circuit allows the shock position vs. time to be monitored on a regular digitizer after easy calibration. The novel feature is the thin section of the gauge producing minimal perturbation in the detonation front.

  14. Harnessing modified manganin technique to study processes of explosive transformation in pyrotechnic compositions

    NASA Astrophysics Data System (ADS)

    Batalov, Sergei


    The paper reviews results of the experimental study of explosive transformation in pyrotechnic compositions with modified manganin technique. In particular, experimental data on pressure profiles recorded with tiny manganin sensors are cited to characterize the effect of parameters of the loading pulse, dispersion and density on peculiarities of explosive transformation in studied pyrotechnic pieces under shock-wave initiation. In the paper are shown the experimental pressure profiles, characteristic for processes of explosive transformation of extended delay. The experimental results prove the effect of density variation of the specimens under study on the process of the explosive transformation. It is felt that for given range of pressures of the incoming shock wave the difference of the explosive transformation history, at equal parameters of loading pulse, is caused also by different dispersion of the initial powder and final porosity of studied specimens. The experimental results provide support for possibility of use of tiny manganin and constantan sensors in studying processes of explosive transformation of pyrotechnic compositions under initiation by divergent shock waves of large curve front and slumping pressure profile.

  15. Studies on microwave and blood-brain barrier interaction

    SciTech Connect

    Lin, J.C.; Lin, M.F.


    This investigation was aimed at correlating changes of blood-brain-barrier permeability with the quantity and distribution of absorbed microwave energy inside the brain of adult Wistar rats anesthetized by sodium pentobarbital. Through use of thermographic methods and a direct-contact applicator at the animal's head, the pattern of absorbed microwave energy was determined. Indwelling catheters were placed in the femoral vein and in the left external carotid artery. Evans blue and sodium fluorescein in isotonic saline were used as visual indicators of barrier permeation. Exposure to pulsed 2,450-MHz radiation for 20 min at average power densities of 0.5, 1, 5, 20, 145 or 1,000 mW/cm2, which resulted in average specific absorption rates (SARs) of 0.04, 0.08, 0.4, 1.6, 11.5 or 80.0 mW/g in the brain, did not produce staining, except in the pineal body, the pituitary gland, and the choroid plexus - regions that normally are highly permeable. Except for these regions, staining was also absent in the brains of sham-exposed animals. The rectal temperature, as monitored by a copper-constantan thermocouple, showed a maximum increase of less than 0.75 degrees C from a mean pre-exposure temperature of 36.6 degrees C. The highest brain temperature recorded in a similar group of animals using a thickfilm carbon thermistor was less than 41.0 degrees C.

  16. A Surface-Enhanced Raman Scattering Sensor Integrated with Battery-Controlled Fluidic Device for Capture and Detection of Trace Small Molecules

    NASA Astrophysics Data System (ADS)

    Zhou, Qitao; Meng, Guowen; Zheng, Peng; Cushing, Scott; Wu, Nianqiang; Huang, Qing; Zhu, Chuhong; Zhang, Zhuo; Wang, Zhiwei


    For surface-enhanced Raman scattering (SERS) sensors, one of the important issues is the development of substrates not only with high SERS-activity but also with strong ability to capture analytes. However, it is difficult to achieve the two goals simultaneously especially when detecting small molecules. Herein a compact battery-controlled nanostructure-assembled SERS system has been demonstrated for capture and detection of trace small molecule pollutants in water. In this SERS fluidic system, an electrical heating constantan wire covered with the vertically aligned ZnO nanotapers decorated with Ag-nanoparticles is inserted into a glass capillary. A mixture of thermo-responsive microgels, Au-nanorods colloids and analyte solution is then filled into the remnant space of the capillary. When the system is heated by switching on the battery, the thermo-responsive microgels shrink, which immobilizes the analyte and drives the Au-nanorod close to each other and close to the Ag-ZnO nanotapers. This process has also created high-density “hot spots” due to multi-type plasmonic couplings in three-dimensional space, amplifying the SERS signal. This integrated device has been successfully used to measure methyl parathion in lake water, showing a great potential in detection of aquatic pollutants.

  17. A Surface-Enhanced Raman Scattering Sensor Integrated with Battery-Controlled Fluidic Device for Capture and Detection of Trace Small Molecules

    PubMed Central

    Zhou, Qitao; Meng, Guowen; Zheng, Peng; Cushing, Scott; Wu, Nianqiang; Huang, Qing; Zhu, Chuhong; Zhang, Zhuo; Wang, Zhiwei


    For surface-enhanced Raman scattering (SERS) sensors, one of the important issues is the development of substrates not only with high SERS-activity but also with strong ability to capture analytes. However, it is difficult to achieve the two goals simultaneously especially when detecting small molecules. Herein a compact battery-controlled nanostructure-assembled SERS system has been demonstrated for capture and detection of trace small molecule pollutants in water. In this SERS fluidic system, an electrical heating constantan wire covered with the vertically aligned ZnO nanotapers decorated with Ag-nanoparticles is inserted into a glass capillary. A mixture of thermo-responsive microgels, Au-nanorods colloids and analyte solution is then filled into the remnant space of the capillary. When the system is heated by switching on the battery, the thermo-responsive microgels shrink, which immobilizes the analyte and drives the Au-nanorod close to each other and close to the Ag-ZnO nanotapers. This process has also created high-density “hot spots” due to multi-type plasmonic couplings in three-dimensional space, amplifying the SERS signal. This integrated device has been successfully used to measure methyl parathion in lake water, showing a great potential in detection of aquatic pollutants. PMID:26238799

  18. Practical system for the direct measurement of magneto-caloric effect by micro-thermocouples.


    Kamarád, J; Kaštil, J; Arnold, Z


    A system for direct measurements of the magneto-caloric effect (MCE) exploits a rapid transport of a sample into or from magnetic field in permanent Halbach-type (1 T) or superconducting (4.7 T) magnets. Time dependence of induced changes of the sample temperature, ΔT(t), is detected directly by the differential Cu-Constantan-Cu micro-thermocouples with time steps of 300 ms. A sample placed inside an evacuated simple LN(2) cryostat is either totally isolated (adiabatic conditions) or partly connected with the copper sample holder (non-adiabatic conditions). The last arrangement (a model of the Brayton cycle) is used to simulate an application of MCE in refrigeration techniques. The relations describing ΔT(t) that allow an analysis of MCE of the studied materials are based on the general cooling law. The effect of the first-order magnetic transition on MCE of selected sample is also demonstrated by non-standard ΔT(t) curves measured in the last mentioned experimental arrangements. PMID:22938309

  19. Finite element analysis of (SA) mechanoreceptors in tactile sensing application

    NASA Astrophysics Data System (ADS)

    N, Syamimi; Yahud, S.


    This paper addresses the structural design of a fingertip model in order to analyse the sensory function of slow adapting (SA) mechanoreceptors by using the finite element analysis (FEA) method. A biologically inspired tactile sensor was designed to mimic a similar response of the human mechanoreceptors in the human glabrous skin. The simulation work was done by using COMSOL Multiphysics. The artificial skin was modelled as a solid square block of silicone elastomer with a semi cylinder protrusion on top. It was modelled as a nearly incompressible and linear hyperelastic material defined by Neo Hookean constitutive law. The sensing element on the other hand was modelled by using constantan alloy mimicking the SA1 receptor. Boundary loads of 1 N/m² to 4 N/m² with the increment of 1 N/m² were applied to the top surface of the protrusion in z and x-direction for normal and shear stress, respectively. The epidermal model base was constrained to maintain the same boundary conditions throughout all simulations. The changes of length experienced by the sensing element were calculated. The simulations result in terms of strain was identified. The simulated result was plotted in terms of sensing element strain against the boundary load and the graph should produce a linear response.

  20. Apparatus for the Measurement of Thermoelectric Power

    NASA Astrophysics Data System (ADS)

    Hishida, Shoji; Ho, Pei-Chun

    The Seebeck Effect refers to the electric potential that is established in a material under an imposed temperature gradient. This effect provides a useful tool for characterizing the thermal and electric transport behavior of materials. A measurement probe is under development in order to measure the Seebeck Coefficient (Thermoelectric Power) of a sample over the temperature range from 10 - 300 K in a cryocooler system. The sample is mounted between two platforms: one that is thermally connected with the measurement probe and another that is thermally isolated, referred to as the cold and hot platforms respectively. A 2k Ω resistance heater on the hot platform is used to establish a temperature gradient across the sample and between the two platforms. A Cernox resistance thermometer measures the temperature of the cold platform, and a Type T differential thermocouple, composed of copper-constantan-copper wires, is used to measure the temperature difference. The probe will be calibrated using the known thermopowers of Nickel, Platinum, and Chromel samples. The performance results of this design will be presented. Research at CSU-Fresno is supported by NSF DMR-1506677. Shoji Hishida is also supported by the Undergraduate Research Grant at CSU Fresno.

  1. Sliding bubbles on a hot horizontal wire in a subcooled bath

    NASA Astrophysics Data System (ADS)

    Duchesne, Alexis; Dubois, Charles; Caps, Hervé


    When a wire is heated up to the boiling point in a liquid bath some bubbles will nucleate on the wire surface. Traditional nucleate boiling theory predicts that bubbles generate from active nucleate site, grow up and depart from the heating surface due to buoyancy and inertia. However, an alternative scenario is presented in the literature for a subcooled bath: bubbles slide along the horizontal wire before departing. New experiments were performed by using a constantan wire and different liquids, varying the injected power. Silicone oil, water and even liquid nitrogen were tested in order to vary wetting conditions, liquid viscosities and surface tensions. We explored the influence of the wire diameter and of the subcooled bath temperature. We observed, of course, sliding motion, but also a wide range of behaviors from bubbles clustering to film boiling. We noticed that bubbles could change moving sense, especially when encountering with another bubble. The bubble speed is carefully measured and can reach more than 100 mm/s for a millimetric bubble. We investigated the dependence of the speed on the different parameters and found that this speed is, for a given configuration, quite independent of the injected power. We understand these phenomena in terms of Marangoni effects. This project has been financially supported by ARC SuperCool contract of the University of Liège.

  2. Decreases in deuterium pumping by St707 getter alloy caused by carbon dioxide preexposure

    SciTech Connect

    Malinowski, M.E.


    Intentional passivation of the deuterium pumping of the solid getter alloy St707 has been attempted by exposing samples of St707 to carbon dioxide at different pressures, temperatures and exposure times relevant for application to the getter modules in the ALT-I pump limiter. It was found that one of the most effective treatments examined was a 30 min, 1 Torr exposure at approximately 100 /sup 0/C. This preexposure kept the getter pumping speed less than 0.001 of its rated value for about 3 min when exposed to deuterium at 1 Torr and 30 /sup 0/C. After this ''incubation'' period, the getter speed increases to values greater than approx.1% of fully activated values. If left under high deuterium pressure, the getter eventually flakes off the substrate. Video observations of the flaking process indicate that individual particles leave the constantan getter substrate at velocities of 1 m/s. Attempts at passivating the getter using oxygen and carbon monoxide were found to be no more effective than using carbon dioxide, suggesting that there is no way to completely passivate the getter with these gases at pressures low enough for application to in situ getter arrays used in tokamaks.

  3. Stress-strain gage measurements on a Nevada Test Site (NTS) event using pairs of triple foil gages

    SciTech Connect

    Kansa, E.J.; Stout, R.B.


    A triple-material stress-strain gage containing foils of ytterbium, manganin, and constantan was tested at LLNL. This gage yields three independent piezoresistance measurements from which an independent set of principal strains and principal stresses can be inferred. We have analyzed the signals from a gage at a specific location buried at a distance from the center of energy of an event at NTS. We inverted the resistivity signals to calculate the stress and strain histories as sensed by the foils. Using the elastic material properties and the traction and displacement conditions at the various material interfaces from the foils to the host geological medium, we calculated the stress and strain histories in the host geological medium. However, because of uncertainties in the elastic properties of the layers of surrounding materials, we calculated significant variations in both the peaks and signatures of the stress and strain histories that could produce the foil stress and strain histories. We conclude that, because of the inclusion problem, accurate measurements of the stress-strain histories in the host geological medium can be adequately addressed only by minimizing, as much as possible, such uncertainties.

  4. A chamber for laboratory studies of atmospheric aerosols and clouds

    NASA Astrophysics Data System (ADS)

    Narus, M. L.; Schoenfelder, N. C.; Na, Y.; Chavasse, L. A.; Disselkamp, R. S.


    A stainless-steel chamber has been constructed and interfaced to a Fourier transform infrared spectrometer for the purpose of studying laboratory simulated atmospheric aerosols and clouds. The chamber is cylindrical in design and is comprised of a double-walled inner assembly that resides within an outer vacuum jacket. The volume of the aerosol sample region is 28 L. By circulating refrigerated methanol between the double walls of the inner assembly, constant temperature control of the sample region can be maintained between 187 and 300 K. A study of temperature uniformity within the chamber at 291, 240, and 187 K revealed a standard deviation in temperature of 1.6 K as determined from measurements made using five copper-constantan thermocouples. Good agreement is obtained between thermocouple measured temperatures and rotational temperatures computed from infrared absorption spectra of methane gas. The chamber described here has been used to examine heterogeneous chemistry of solid powder samples. A technique of generating an aerosol sample by rapidly dispersing a solid powder in a gas is presented. The half-life of a γ-alumina aerosol sample was measured to be 25 min.

  5. Evaluation of the effect of V2O5 on the electrical and thermoelectric properties of poly(vinyl alcohol)/graphene nanoplatelets nanocomposite

    NASA Astrophysics Data System (ADS)

    Morad, M.; Fadlallah, M. M.; Hassan, M. A.; Sheha, E.


    The aim of this contribution is to introduce high performance materials for thermoelectric devices. A nanopolymer composite of PVAGNP ((polyvinyl alcohol ((PVA)0.6/graphene nanoplatelets (GNP)0.4))1-x(V2O5)x where x = 0, 2.5, 5, 7.5 and 10 wt% has been prepared using a solution cast technique. The influence of V2O5 additives on the morphology, structure, thermal and electrical properties of PVA has been examined by FTIR, XRD, TGA, DC and IV techniques. The disassociation of V2O5 to (V4+) and (V5+) in the composites acts as a co-bridge which can facilitate the translational electronic motion, which enhances the charge carrier mobility and the electrical conductivity. A prototype cell was constructed using (PVAGNP)1-x(GNP)x nanocomposites with constantan wire. The addition of V2O5 improves the thermoelectric properties of the (PVA)0.6(GNP)0.4 nanocomposite, where the Seebeck coefficient is increased from 23.1 to 45.8 μV K-1 from 0 to 10 wt% V2O5, respectively. The power factor is increased from 1.17 × 10-2 to 36.30 × 10-2 μWm-1 K-2 from 0 to 10 wt% V2O5, respectively, and the ZT is increased from 4.47 × 10-9 to 1.46 × 10-7.

  6. Intrapulpal temperatures during pulsed Nd:YAG laser treatment of dentin, in vitro.


    White, J M; Fagan, M C; Goodis, H E


    Lasers are being used for soft tissue removal, caries removal, and treatment of root surface sensitivity. One concern for laser safety is that the heat produced at the irradiated root surface may diffuse to the pulp causing irreversible pulpal damage. To test this heat diffusion, copper-constantan thermocouples were inserted into the radicular pulp canals of extracted teeth. Simulating direct exposure which might occur during gingival excision, superficial caries removal, and modification of the dentin surface for treatment of root surface sensitivity, a 2 mm2 area of the external root surface was uniformly irradiated with a pulsed Nd:YAG laser using a 320 microns diameter fiber optic contact probe. Power was varied from 0.3 to 3.0 W with frequencies of 10 and 20 Hz. Temperature changes during cavity preparations using a high speed handpiece with air coolant were also recorded. Repeated measures ANOVA (P < or = 0.05) indicated that intrapulpal temperatures increased as a function of power, frequency, and time. Intrapulpal temperatures decreased as remaining dentin thickness (0.2 to 2.0 mm) increased for each laser parameter. Irradiation of dentin using a Nd:YAG pulsed laser, within the treatment times, powers, and frequencies with adequate remaining dentin thickness, as outlined in this paper, should not cause devitalizing intrapulpal temperature rises. PMID:8164119

  7. Aeroheating Measurement of Apollo Shaped Capsule with Boundary Layer Trip in the Free-piston Shock Tunnel HIEST

    NASA Technical Reports Server (NTRS)

    Hideyuki, TANNO; Tomoyuki, KOMURO; Kazuo, SATO; Katsuhiro, ITOH; Lillard, Randolph P.; Olejniczak, Joseph


    An aeroheating measurement test campaign of an Apollo capsule model with laminar and turbulent boundary layer was performed in the free-piston shock tunnel HIEST at JAXA Kakuda Space Center. A 250mm-diameter 6.4%-scaled Apollo CM capsule model made of SUS-304 stainless steel was applied in this study. To measure heat flux distribution, the model was equipped with 88 miniature co-axial Chromel-Constantan thermocouples on the heat shield surface of the model. In order to promote boundary layer transition, a boundary layer trip insert with 13 "pizza-box" isolated roughness elements, which have 1.27mm square, were placed at 17mm below of the model geometric center. Three boundary layer trip inserts with roughness height of k=0.3mm, 0.6mm and 0.8mm were used to identify the appropriate height to induce transition. Heat flux records with or without roughness elements were obtained for model angles of attack 28º under stagnation enthalpy between H(sub 0)=3.5MJ/kg to 21MJ/kg and stagnation pressure between P(sub 0)=14MPa to 60MPa. Under the condition above, Reynolds number based on the model diameter was varied from 0.2 to 1.3 million. With roughness elements, boundary layer became fully turbulent less than H(sub 0)=9MJ/kg condition. However, boundary layer was still laminar over H(sub 0)=13MJ/kg condition even with the highest roughness elements. An additional experiment was also performed to correct unexpected heat flux augmentation observed over H(sub 0)=9MJ/kg condition.

  8. Uncertainty analysis of thermocouple measurements used in normal and abnormal thermal environment experiments at Sandia's Radiant Heat Facility and Lurance Canyon Burn Site.

    SciTech Connect

    Nakos, James Thomas


    It would not be possible to confidently qualify weapon systems performance or validate computer codes without knowing the uncertainty of the experimental data used. This report provides uncertainty estimates associated with thermocouple data for temperature measurements from two of Sandia's large-scale thermal facilities. These two facilities (the Radiant Heat Facility (RHF) and the Lurance Canyon Burn Site (LCBS)) routinely gather data from normal and abnormal thermal environment experiments. They are managed by Fire Science & Technology Department 09132. Uncertainty analyses were performed for several thermocouple (TC) data acquisition systems (DASs) used at the RHF and LCBS. These analyses apply to Type K, chromel-alumel thermocouples of various types: fiberglass sheathed TC wire, mineral-insulated, metal-sheathed (MIMS) TC assemblies, and are easily extended to other TC materials (e.g., copper-constantan). Several DASs were analyzed: (1) A Hewlett-Packard (HP) 3852A system, and (2) several National Instrument (NI) systems. The uncertainty analyses were performed on the entire system from the TC to the DAS output file. Uncertainty sources include TC mounting errors, ANSI standard calibration uncertainty for Type K TC wire, potential errors due to temperature gradients inside connectors, extension wire uncertainty, DAS hardware uncertainties including noise, common mode rejection ratio, digital voltmeter accuracy, mV to temperature conversion, analog to digital conversion, and other possible sources. Typical results for 'normal' environments (e.g., maximum of 300-400 K) showed the total uncertainty to be about {+-}1% of the reading in absolute temperature. In high temperature or high heat flux ('abnormal') thermal environments, total uncertainties range up to {+-}2-3% of the reading (maximum of 1300 K). The higher uncertainties in abnormal thermal environments are caused by increased errors due to the effects of imperfect TC attachment to the test item. 'Best

  9. Pulvinus activity, leaf movement and leaf water-use efficiency of bush bean ( Phaseplus vulgaris L.) in a hot environment

    NASA Astrophysics Data System (ADS)

    Raeini-Sarjaz, Mahmoud; Chalavi, Vida


    Pulvinus activity of Phaseolus species in response to environmental stimuli plays an essential role in heliotropic leaf movement. The aims of this study were to monitor the continuous daily pulvinus movement and pulvinus temperature, and to evaluate the effects of leaf movements, on a hot day, on instantaneous leaf water-use efficiency (WUEi), leaf gas exchange, and leaf temperature. Potted plants of Phaseolus vulgaris L. var. Provider were grown in Chicot sandy loam soil under well-watered conditions in a greenhouse. When the second trifoliate leaf was completely extended, one plant was selected to measure pulvinus movement using a beta-ray gauging (BRG) meter with a point source of thallium-204 (204Tl). Leaf gas exchange measurements took place on similar leaflets of three plants at an air temperature interval of 33-42°C by a steady-state LI-6200 photosynthesis system. A copper-constantan thermocouple was used to monitor pulvinus temperature. Pulvinus bending followed the daily diurnal rhythm. Significant correlations were found between the leaf-incident angle and the stomatal conductance ( R 2 = 0.54; P < 0.01), and photosynthesis rate ( R 2 = 0.84; P < 0.01). With a reduction in leaf-incidence angle and increase in air temperature, WUEi was reduced. During the measurements, leaf temperature remained below air temperature and was a significant function of air temperature ( r = 0.92; P < 0.01). In conclusion, pulvinus bending followed both light intensity and air temperature and influenced leaf gas exchange.

  10. Measurement of Low Level Explosives Reaction in the Two-Dimensional Steven Impact Test

    SciTech Connect

    Forbes, J.W.; Tarver, C.M.; Chidester, S.K.; Garcia, F.; Greenwood, D.W.; Garza, R.


    The two-dimensional Steven impact test has been developed to be reproducible and amenable to computer modeling. This test has a hemispherical projectile traveling at tens of m/s impacting a metal cased explosive target. To assist in the understanding of this safety test, two-dimensional shock wave gauge techniques were used to measure the pressures of a few kilobars and times of reactions less than a millisecond. This work is in accord with a long-term goal to develop two-dimensional shock diagnostic techniques that are more than just time of arrival indicators. Experiments were performed where explosives were impacted at levels below shock initiation levels but caused low level reactions. Carbon foil and carbon resistor pressure gauges were used to measure pressures and time of events. The carbon resistor gauges indicate a late time low level reaction at 350 {micro}s after impact of the hemispherical projectile creating 0.5-6 kb peak shocks at the center of PBX 9501 (HMX/Estane/BDNPA-F; 95/2.5/2.5 wt %) explosive discs. The Steven test calculations are based on an ignition and growth criteria and found that the low level reaction occurs at 335 {micro}s, which is in good agreement with the experimental data. Some additional experiments simulating the Steven impact test were done on a gas gun with carbon foil and constantan strain gauges in a PMMA target. Hydrodynamic calculations can be used to evaluate the gauge performance in these experiments and check the lateral strain measurements.

  11. Multi-component stress history measurements and analysis

    SciTech Connect

    Stout, R.B.; Larson, D.B.


    Piezoresistance foil gages were tested dynamically in multi-component stress-strain experiments in order that the actual shock wave conditions of underground nuclear testing could be more closely simulated. The multi-component stress-strain histories were created in polymethylmethacrylate (PMMA) by using chemical explosions to generate spherical shock waves. In addition to the resistivity measurements from the foil gages, particle velocity was also measured at several radial positions from the explosion to provide a complete set of data for analysis. The gage interpretation (inverse) problem for multi-component stress-strain fields requires obtaining a sufficient number of independent measurements so that the different stress-strain components influencing the gage response can be uniquely inferred. The piezoresistance measurements provided data from a triple material foil gage and from ytterbium foil gages (bare gages). An analysis shows that the triple material gage containing foils of ytterbium, manganin, and constantan provided three independent resistivity measurements for the gage oriented in a perpendicular direction relative to the radial propagating shock front. An analysis of the ytterbium foil gages, which were tested in both perpendicular (normal) and parallel (tangential) directions relative to the radial shock front, show the resistivity responses from these two orientations are independent measurements. The results from the analyses of the gages compared well with experimental data. This analysis shows clearly that the material properties of the foil, the dimensions of the foil, and the material surrounding the foil greatly influence the total resistivity response of foil gages in a multi-component stress-strain field. 25 refs., 16 figs.

  12. High-Speed Automated Tester for Vacuum Chamber Feedthrough Connectors and Cables

    NASA Technical Reports Server (NTRS)

    Swope, Robert H.; Powers, Edward I. (Technical Monitor)


    The Goddard Space Flight Center's thermal vacuum laboratory has developed a high-speed automated system for testing the integrity of 37-pin MIL-C-5015 cylindrical electrical feedthrough connectors used on penetration plates of thermal vacuum chambers. The system consists of a desktop PC driving a data acquisition front end. The latter measures the resistance through each pin of the connector and the resistance from each pin to all other pins and the connector shell. In addition to identifying unacceptable feedthroughs, the system is also used for testing cables. In the special case of Type T thermocouples (used almost exclusively at the lab), the difference in resistance between the copper and constantan wires provides positive proof of accidentally reversed connector wiring. Data acquisition time to completely test a cable or feedthrough connector is less than thirty seconds. The system provides a hardcopy printout of the resistance readings. Connectors or cables with fewer wires are tested using simple adapter cables. Initial tests indicate that the performance of a given feedthrough connector can be predicted on the basis of measured resistance readings, reducing ongoing cost of connector replacement. The opportunity to positively certify the integrity of cables, cable connectors and feedthroughs before the start of a thermal vacuum test minimizes the likelihood of a circuit problem that would require returning the chamber to ambient conditions for repair. This system has two principal advantages for the Goddard thermal vacuum laboratory. Its only significant cost was the labor to fabricate the test cable and shorting cable -- about 40 man-hours total. The system was built around a computer and data acquisition unit that were already on hand. The second advantage is that it very quickly tests both of the parameters that are essential.

  13. Unileg Thermoelectric Generator Design for Oxide Thermoelectrics and Generalization of the Unileg Design Using an Idealized Metal

    NASA Astrophysics Data System (ADS)

    Wijesekara, Waruna; Rosendahl, Lasse; Brown, David R.; Snyder, G. Jeffrey


    The unileg thermoelectric generator (U-TEG) is an increasingly popular concept in the design of thermoelectric generators (TEGs). In this study, an oxide U-TEG design for high-temperature applications is introduced. For the unicouple TEG design, Ca3Co4O9 and Al-doped ZnO are used as the p- and n-leg thermoelectric materials, respectively. For the U-TEG design, constantan and Ca3Co4O9 are employed as conductor and semiconductor, respectively. The reduced current approach (RCA) technique is used to design the unicouple TEG and U-TEG in order to obtain the optimal area ratio. When both the unicouple TEG and U-TEG were subjected to a heat flux of 20 W/cm2, the volumetric power density was 0.18 W/cm3 and 0.44 W/cm3, respectively. Thermal shorting between the hot and cold sides of the generator through the highly thermally conducting conductor, which is one of the major drawbacks of the U-TEG, is overcome by using the optimal area ratio for conductor and semiconductor given by the RCA. The results are further confirmed by finite-element analysis using COMSOL Multiphysics software. Furthermore, the U-TEG design is generalized by using an idealized metal with zero Seebeck coefficient. Even though the idealized metal has no impact on the power output of the U-TEG and all the power in the system is generated by the semiconductor, the U-TEG design succeeded in producing a higher volumetric power density than the unicouple TEG design.

  14. An Innovative Modeling and Measurement Approach to Improve Rice Water Use Efficiency in California

    NASA Astrophysics Data System (ADS)

    Montazar, A.; Little, C.; Rejmanek, H.; Tindula, G.; Snyder, R. L.


    California is amongst the top rice producing states in the USA, and more than 95 percent of California's rice is grown in the Sacramento Valley. Based on older literature, the rice water requirement (ETc), ranges between 914 and 1,100 mm. In this study, the actual rice water requirement was measured using the residual of the energy balance method over three paddy rice fields during 2011-2013 seasons in the Sacramento Valley. Net radiation and ground heat flux density were measured, and both eddy covariance (EC) and the surface renewal (SR) technique were employed to determine the sensible heat flux density. The surface renewal method uses high frequency temperature measurements from fine wire thermocouples above the canopy. Mean amplitude and duration of the ramps over half hour periods were determined using a structure function and the characteristics are employed to estimate the direction and magnitude of sensible heat flux using the ratio of the amplitude to the ramp duration as the change in temperature per unit time and the volumetric heat capacity of the air to estimate the magnitude of the heat flux. In the study, 76.2 mm diameter chromel-constantan thermocouples were used to measure high frequency temperature at 10 Hz. The results indicate that there is considerable variability in rice water use both spatially and temporally. The average three-year measured ET of the experimental fields located in Butte County was 734 and 725 mm; and in Colusa County was 771 mm. A typical crop coefficient (Kc) curve was derived from the measured ETc and reference ET (ETo) data. Spatial estimates of monthly climate data from the Sacramento Valley were used to calculate monthly mean ETo, and smooth curve fits of the monthly data gave estimates of typical daily ETo. The daily ETc was calculated as the product of ETo and Kc, and seasonal ETc was calculated by summing the daily ETc values. The results reveal that the seasonal rice ETc was less than earlier estimates. Surface

  15. Nowa: Concept of Operation Principle of The Prototype "new Orthogonal Heat-transfer Anemometer"

    NASA Astrophysics Data System (ADS)

    Scharnhorst, W.; Richner, H.; Joss, J.

    Various meteorological applications ask for long-term measurements of environmen- tal quantities in severe weather conditions at locations difficult to access. So there is a need for robust devices that measure continuously despite of extreme tempera- tures, strong winds, icing and heavy precipitation. The NOWA (Neues Orthogonales Wärmeübergangs-Anemometer) is a heated instrument based on measuring the heat transfer and aiming to fulfil the mentioned requirements. It is 725 mm long using a 337 mm long sensor rod with a diameter of 16 mm. The sensitive elements are placed in the top of the instrument. Apart from wind speed and wind direction, also air temperature, precipitation, and the icing rate are estimated. These quantities are determined by mea- suring temperature values at various locations of the instrument as well as the power needed to keep the sensor and its housing heated. A heated Pt100 is embedded in ce- ramics placed vertically in the centre of the sensor head. Air motion cools the Pt100. Electrical power is used to keep the temperature of the sensor head constant. The power dissipated by the Pt100 is measured. At high wind speed, the wind velocity is determined using the concept of hot-wire anemometry. Four copper-constantane ther- moelements are aligned in North-South- and East-West-direction around the Pt100. In calm air, these elements sense the uniform temperature field created by the heated Pt100 element. Wind will lower the temperature at the Lee-side, whereas the elements placed downwind become warmer. The differences in temperature are related to the wind direction and are used to estimate the wind speed at low velocities. The NOWA is protected against precipitation and icing by its housing and a heated metal screen with a cap. The total heat flux at the instrument's surface can be determined by measur- ing the temperature distribution on the housing. Depending on the weather situation, this heat transfer is either caused by wind

  16. U.S. Space Radioisotope Power Systems and Applications: Past, Present and Future

    NASA Technical Reports Server (NTRS)

    Cataldo, Robert L.; Bennett, Gary L.


    -1906) and R. J. Strut. Almost 100 years ago, in 1913, English physicist H. G. J. Moseley (1887-1915) constructed the first nuclear battery using a vacuum flask and 20 mCi of radium (Corliss and Harvey, 1964, Proceedings of the Royal Society, 1913). After World War II, serious interest in radioisotope power systems in the U.S. was sparked by studies of space satellites such as North American Aviation s 1947 report on nuclear space power and the RAND Corporation s 1949 report on radioisotope power. (Greenfield, 1947, Gendler and Kock, 1949). Radioisotopes were also considered in early studies of nuclear-powered aircraft (Corliss and Harvey, 1964). In 1951, the U.S. Atomic Energy Commission (AEC) signed several contracts to study a 1-kWe space power plant using reactors or radioisotopes. Several of these studies, which were completed in 1952, recommended the use of RPS. (Corliss and Harvey, 1964). In 1954, the RAND Corporation issued the summary report of the Project Feedback military satellite study in which radioisotope power was considered (Lipp and Salter, 1954, RAND). Paralleling these studies, in 1954, K. C. Jordan and J. H. Birden of the AEC s Mound Laboratory conceived and built the first RTG using chromel-constantan thermocouples and a polonium-210 (210Po or Po-210) radioisotope heat source (see Figure 2). While the power produced (1.8 mWe) was low by today s standards, this first RTG showed the feasibility of RPS. A second thermal battery was built with more Po-210, producing 9.4 mWe. Jordan and Birden concluded that the Po-210 thermal battery would have about ten times the energy of ordinary dry cells of the same mass (Jordan and Birden, 1954). The heat source consisted of a 1-cm-diameter sphere of 57 Ci (1.8 Wt) of Po-210 inside a capsule of nickel-coated cold-rolled steel all inside a container of Lucite. The thermocouples were silver-soldered chromel-constantan. The thermal battery produced 1.8 mWe.