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Sample records for sample temperature modeling

  1. Modeling the temperature-dependent peptide vibrational spectra based on implicit-solvent model and enhance sampling technique

    NASA Astrophysics Data System (ADS)

    Tianmin, Wu; Tianjun, Wang; Xian, Chen; Bin, Fang; Ruiting, Zhang; Wei, Zhuang

    2016-01-01

    We herein review our studies on simulating the thermal unfolding Fourier transform infrared and two-dimensional infrared spectra of peptides. The peptide-water configuration ensembles, required forspectrum modeling, aregenerated at a series of temperatures using the GBOBC implicit solvent model and the integrated tempering sampling technique. The fluctuating vibrational Hamiltonians of the amide I vibrational band are constructed using the Frenkel exciton model. The signals are calculated using nonlinear exciton propagation. The simulated spectral features such as the intensity and ellipticity are consistent with the experimental observations. Comparing the signals for two beta-hairpin polypeptides with similar structures suggests that this technique is sensitive to peptide folding landscapes. Project supported by the National Natural Science Foundation of China (Grant No. 21203178), the National Natural Science Foundation of China (Grant No. 21373201), the National Natural Science Foundation of China (Grant No. 21433014), the Science and Technological Ministry of China (Grant No. 2011YQ09000505), and “Strategic Priority Research Program” of the Chinese Academy of Sciences (Grant Nos. XDB10040304 and XDB100202002).

  2. Temperature Control Diagnostics for Sample Environments

    SciTech Connect

    Santodonato, Louis J; Walker, Lakeisha MH; Church, Andrew J; Redmon, Christopher Mckenzie

    2010-01-01

    In a scientific laboratory setting, standard equipment such as cryocoolers are often used as part of a custom sample environment system designed to regulate temperature over a wide range. The end user may be more concerned with precise sample temperature control than with base temperature. But cryogenic systems tend to be specified mainly in terms of cooling capacity and base temperature. Technical staff at scientific user facilities (and perhaps elsewhere) often wonder how to best specify and evaluate temperature control capabilities. Here we describe test methods and give results obtained at a user facility that operates a large sample environment inventory. Although this inventory includes a wide variety of temperature, pressure, and magnetic field devices, the present work focuses on cryocooler-based systems.

  3. Recommended Maximum Temperature For Mars Returned Samples

    NASA Technical Reports Server (NTRS)

    Beaty, D. W.; McSween, H. Y.; Czaja, A. D.; Goreva, Y. S.; Hausrath, E.; Herd, C. D. K.; Humayun, M.; McCubbin, F. M.; McLennan, S. M.; Hays, L. E.

    2016-01-01

    The Returned Sample Science Board (RSSB) was established in 2015 by NASA to provide expertise from the planetary sample community to the Mars 2020 Project. The RSSB's first task was to address the effect of heating during acquisition and storage of samples on scientific investigations that could be expected to be conducted if the samples are returned to Earth. Sample heating may cause changes that could ad-versely affect scientific investigations. Previous studies of temperature requirements for returned mar-tian samples fall within a wide range (-73 to 50 degrees Centigrade) and, for mission concepts that have a life detection component, the recommended threshold was less than or equal to -20 degrees Centigrade. The RSSB was asked by the Mars 2020 project to determine whether or not a temperature requirement was needed within the range of 30 to 70 degrees Centigrade. There are eight expected temperature regimes to which the samples could be exposed, from the moment that they are drilled until they are placed into a temperature-controlled environment on Earth. Two of those - heating during sample acquisition (drilling) and heating while cached on the Martian surface - potentially subject samples to the highest temperatures. The RSSB focused on the upper temperature limit that Mars samples should be allowed to reach. We considered 11 scientific investigations where thermal excursions may have an adverse effect on the science outcome. Those are: (T-1) organic geochemistry, (T-2) stable isotope geochemistry, (T-3) prevention of mineral hydration/dehydration and phase transformation, (T-4) retention of water, (T-5) characterization of amorphous materials, (T-6) putative Martian organisms, (T-7) oxidation/reduction reactions, (T-8) (sup 4) He thermochronometry, (T-9) radiometric dating using fission, cosmic-ray or solar-flare tracks, (T-10) analyses of trapped gasses, and (T-11) magnetic studies.

  4. Finite sample effect in temperature gradient focusing.

    PubMed

    Lin, Hao; Shackman, Jonathan G; Ross, David

    2008-06-01

    Temperature gradient focusing (TGF) is a new and promising equilibrium gradient focusing method which can provide high concentration factors for improved detection limits in combination with high-resolution separation. In this technique, temperature-dependent buffer chemistry is employed to generate a gradient in the analyte electrophoretic velocity. By the application of a convective counter-flow, a zero-velocity point is created within a microchannel, at which location the ionic analytes accumulate or focus. In general, the analyte concentration is small when compared with buffer ion concentrations, such that the focusing mechanism works in the ideal, linearized regime. However, this presumption may at times be violated due to significant sample concentration growth or the use of a low-concentration buffer. Under these situations the sample concentration becomes non-negligible and can induce strong nonlinear interactions with buffer ions, which eventually lead to peak shifting and distortion, and the loss of detectability and resolution. In this work we combine theory, simulation, and experimental data to present a detailed study on nonlinear sample-buffer interactions in TGF. One of the key results is the derivation of a generalized Kohlrausch regulating function (KRF) that is valid for systems in which the electrophoretic mobilities are not constant but vary spatially. This generalized KRF greatly facilitates analysis, allowing reduction of the problem to a single equation describing sample concentration evolution, and is applicable to other problems with heterogeneous electrophoretic mobilities. Using this sample evolution equation we have derived an understanding of the nonlinear peak deformation phenomenon observed experimentally in TGF. We have used numerical simulations to validate our theory and to quantitatively predict TGF. Our simulation results demonstrate excellent agreement with experimental data, and also indicate that the proper inclusion of

  5. Multiphoton cryo microscope with sample temperature control

    NASA Astrophysics Data System (ADS)

    Breunig, H. G.; Uchugonova, A.; König, K.

    2013-02-01

    We present a multiphoton microscope system which combines the advantages of multiphoton imaging with precise control of the sample temperature. The microscope provides online insight in temperature-induced changes and effects in plant tissue and animal cells with subcellular resolution during cooling and thawing processes. Image contrast is based on multiphoton fluorescence intensity or fluorescence lifetime in the range from liquid nitrogen temperature up to +600°C. In addition, micro spectra from the imaged regions can be recorded. We present measurement results from plant leaf samples as well as Chinese hamster ovary cells.

  6. Temperature effects: methane generation from landfill samples

    SciTech Connect

    Hartz, K.E.; Ham, R.K.; Klink, R.E.

    1982-08-01

    The objective of this investigation was to study the impact of temperature variations on the rate of methane generation from solid waste. The temperatures investigated ranged from 21/sup 0/C to 48/sup 0/C. Two approaches were applied. These were short term residence at seven different temperatures and intermediate term residence at two different temperatures. For the short term studies, samples were obtained from the Freshkills landfill (N.Y.) and the Operating Industries landfill (Calif.). Three samples were used in the intermediate term studies, and were from Palos Verdes landfill and Menlo Park landfill, both in California. From the short term results, energy of activation values of 22.4 kilo calories per mole to 23.7 kilo calories per mole were calculated. The intermediate term results produced values ranging from 18.7 to 21.8 kilo calories per mole. From the results it was concluded that some minor population shifts occurred with minor temperature changes but all of the energy of activation values were higher than any previous reportings. In addition, the temperature of 41/sup 0/C was found to be the optimum for methane generation on a short term basis.

  7. Coercivity maxima at low temperatures. [of lunar samples

    NASA Technical Reports Server (NTRS)

    Schwerer, F. C.; Nagata, T.

    1974-01-01

    Recent measurements have shown that the magnetic coercive forces of some Apollo lunar samples show an unexpected decrease with decreasing temperature at cryogenic temperatures. This behavior can be explained quantitatively in terms of a model which considers additive contributions from a soft, reversible magnetic phase and from a harder, hysteretic magnetic phase.

  8. Temperature effects: methane generation from landfill samples

    SciTech Connect

    Hartz, K.E.; Klink, R.E.; Ham, R.K.

    1982-08-01

    The objective of the investigation described to study the impact of temperature variations on the rate of methane generation from solid waste. The temperatures investigated ranged from 21/sup 0/C to 46/sup 0/C. Two approaches were applied. These were short term residence at seven different temperatures and intermediate term residence at two different temperatures. From the short term results, energy of activation values of 22.4 kilo calories per mole to 23.7 kilo calories per mole were calculated. The temperature of 41/sup 0/C was found to be the optimum for methane generation on a short term basis. 8 refs.

  9. Apparatus for low temperature thermal desorption spectroscopy of portable samples

    NASA Astrophysics Data System (ADS)

    Stuckenholz, S.; Büchner, C.; Ronneburg, H.; Thielsch, G.; Heyde, M.; Freund, H.-J.

    2016-04-01

    An experimental setup for low temperature thermal desorption spectroscopy (TDS) integrated in an ultrahigh vacuum-chamber housing a high-end scanning probe microscope for comprehensive multi-tool surface science analysis is described. This setup enables the characterization with TDS at low temperatures (T > 22 K) of portable sample designs, as is the case for scanning probe optimized setups or high-throughput experiments. This combination of techniques allows a direct correlation between surface morphology, local spectroscopy, and reactivity of model catalysts. The performance of the multi-tool setup is illustrated by measurements of a model catalyst. TDS of CO from Mo(001) and from Mo(001) supported MgO thin films were carried out and combined with scanning tunneling microscopy measurements.

  10. Apparatus for low temperature thermal desorption spectroscopy of portable samples.

    PubMed

    Stuckenholz, S; Büchner, C; Ronneburg, H; Thielsch, G; Heyde, M; Freund, H-J

    2016-04-01

    An experimental setup for low temperature thermal desorption spectroscopy (TDS) integrated in an ultrahigh vacuum-chamber housing a high-end scanning probe microscope for comprehensive multi-tool surface science analysis is described. This setup enables the characterization with TDS at low temperatures (T > 22 K) of portable sample designs, as is the case for scanning probe optimized setups or high-throughput experiments. This combination of techniques allows a direct correlation between surface morphology, local spectroscopy, and reactivity of model catalysts. The performance of the multi-tool setup is illustrated by measurements of a model catalyst. TDS of CO from Mo(001) and from Mo(001) supported MgO thin films were carried out and combined with scanning tunneling microscopy measurements. PMID:27131703

  11. Spin models and boson sampling

    NASA Astrophysics Data System (ADS)

    Garcia Ripoll, Juan Jose; Peropadre, Borja; Aspuru-Guzik, Alan

    Aaronson & Arkhipov showed that predicting the measurement statistics of random linear optics circuits (i.e. boson sampling) is a classically hard problem for highly non-classical input states. A typical boson-sampling circuit requires N single photon emitters and M photodetectors, and it is a natural idea to rely on few-level systems for both tasks. Indeed, we show that 2M two-level emitters at the input and output ports of a general M-port interferometer interact via an XY-model with collective dissipation and a large number of dark states that could be used for quantum information storage. More important is the fact that, when we neglect dissipation, the resulting long-range XY spin-spin interaction is equivalent to boson sampling under the same conditions that make boson sampling efficient. This allows efficient implementations of boson sampling using quantum simulators & quantum computers. We acknowledge support from Spanish Mineco Project FIS2012-33022, CAM Research Network QUITEMAD+ and EU FP7 FET-Open Project PROMISCE.

  12. Experiment 2030. EE-2 Temperature Log and Downhole Water Sample

    SciTech Connect

    Grigsby, Charles O.

    1983-07-29

    A temperature log and downhole water sample run were conducted in EE-2 on July 13, 1983. The temperature log was taken to show any changes which had occurred in the fracture-to-wellbore intersections as a result of the Experiment 2020 pumping and to locate fluid entries for taking the water sample. The water sample was requested primarily to determine the arsenic concentration in EE-2 fluids (see memo from C.Grigsby, June 28, 1983 concerning arsenic in EE-3 samples.) The temperature log was run using the thermistor in the ESS-6 water samples.

  13. Proximity effect thermometer for local temperature measurements on mesoscopic samples.

    SciTech Connect

    Aumentado, J.; Eom, J.; Chandrasekhar, V.; Baldo, P. M.; Rehn, L. E.; Materials Science Division; Northwestern Univ; Univ. of Chicago

    1999-11-29

    Using the strong temperature-dependent resistance of a normal metal wire in proximity to a superconductor, we have been able to measure the local temperature of electrons heated by flowing a direct-current (dc) in a metallic wire to within a few tens of millikelvin at low temperatures. By placing two such thermometers at different parts of a sample, we have been able to measure the temperature difference induced by a dc flowing in the samples. This technique may provide a flexible means of making quantitative thermal and thermoelectric measurements on mesoscopic metallic samples.

  14. Axonal model for temperature stimulation.

    PubMed

    Fribance, Sarah; Wang, Jicheng; Roppolo, James R; de Groat, William C; Tai, Changfeng

    2016-10-01

    Recent studies indicate that a rapid increase in local temperature plays an important role in nerve stimulation by laser. To analyze the temperature effect, our study modified the classical HH axonal model by incorporating a membrane capacitance-temperature relationship. The modified model successfully simulated the generation and propagation of action potentials induced by a rapid increase in local temperature when the Curie temperature of membrane capacitance is below 40 °C, while the classical model failed to simulate the axonal excitation by temperature stimulation. The new model predicts that a rapid increase in local temperature produces a rapid increase in membrane capacitance, which causes an inward membrane current across the membrane capacitor strong enough to depolarize the membrane and generate an action potential. If the Curie temperature of membrane capacitance is 31 °C, a temperature increase of 6.6-11.2 °C within 0.1-2.6 ms is required for axonal excitation and the required increase is smaller for a faster increase. The model also predicts that: (1) the temperature increase could be smaller if the global axon temperature is higher; (2) axons of small diameter require a smaller temperature increase than axons of large diameter. Our study indicates that the axonal membrane capacitance-temperature relationship plays a critical role in inducing the transient membrane depolarization by a rapidly increasing temperature, while the effects of temperature on ion channel kinetics cannot induce depolarization. The axonal model developed in this study will be very useful for analyzing the axonal response to local heating induced by pulsed infrared laser. PMID:27342462

  15. Calibration of tip and sample temperature of a scanning tunneling microscope using a superconductive sample

    SciTech Connect

    Stocker, Matthias; Pfeifer, Holger; Koslowski, Berndt

    2014-05-15

    The temperature of the electrodes is a crucial parameter in virtually all tunneling experiments. The temperature not only controls the thermodynamic state of the electrodes but also causes thermal broadening, which limits the energy resolution. Unfortunately, the construction of many scanning tunneling microscopes inherits a weak thermal link between tip and sample in order to make one side movable. Such, the temperature of that electrode is badly defined. Here, the authors present a procedure to calibrate the tip temperature by very simple means. The authors use a superconducting sample (Nb) and a standard tip made from W. Due to the asymmetry in the density of states of the superconductor (SC)—normal metal (NM) tunneling junction, the SC temperature controls predominantly the density of states while the NM controls the thermal smearing. By numerically simulating the I-V curves and numerically optimizing the tip temperature and the SC gap width, the tip temperature can be accurately deduced if the sample temperature is known or measureable. In our case, the temperature dependence of the SC gap may serve as a temperature sensor, leading to an accurate NM temperature even if the SC temperature is unknown.

  16. Helium POT System for Maintaining Sample Temperature after Cryocooler Deactivation

    NASA Astrophysics Data System (ADS)

    Haid, B. J.

    2006-04-01

    A system for maintaining a sample at a constant temperature below 10 K after deactivating the cooling source is demonstrated. In this system, the cooling source is a 4 K GM cryocooler that is joined with the sample through an extension that consists of a helium pot and a thermal resistance. Upon stopping the cryocooler, the power applied to a heater located on the sample side of the thermal resistance is decreased gradually to maintain an appropriate temperature rise across the thermal resistance as the helium pot warms. The sample temperature is held constant in this manner without the use of solid or liquid cryogens and without mechanically disconnecting the sample from the cooler. Shutting off the cryocooler significantly reduces sample motion that results from vibration and expansion/contraction of the cold-head housing. The reduction in motion permits certain procedures that are very sensitive to sample position stability, but are performed with limited duration. A proof-of-concept system was built and operated with the helium pot pressurized to the cryocooler's charge pressure. A sample with 200 mW of continuous heat dissipation was maintained at 7 K while the cryocooler operated intermittently with a duty cycle of 9.5 minutes off and 20 minutes on.

  17. CORRECTINH LAND SURFACE MODEL PREDICTIONS FOR THE IMPACT OF SPARSELY SAMPLED RAINFALL RATE RETRIEVALS USING AN ENSEMBLE KALMAN FILTER AND REMOTE SEURFACE BRIGHTNESS TEMPERATURE OBSERVATIONS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Current attempts to measure short-term (< 1 month) rainfall accumulations using spaceborne radiometers are characterized by large sampling errors associated with relatively infrequent observation rates (2 to 8 measurements per day). This degrades the value of spaceborne rainfall retrievals for the ...

  18. Noncontact true temperature measurement. [of levitated sample using laser pyrometer

    NASA Technical Reports Server (NTRS)

    Lee, Mark C.; Allen, James L.

    1987-01-01

    A laser pyrometer has been developed for acquiring the true temperature of a levitated sample. The laser beam is first expanded to cover the entire cross-sectional surface of the target. For calibration of such a system, the reflectivity signal of an ideal 0.95 cm diameter gold-coated sphere (reflectivity = 0.99) is used as the reference for any other real targets. The emissivity of the real target can then be calculated. The overall system constant is obtained by passively measuring the radiance of a blackbody furnace (emissivity = 1.0) at a known, arbitrary temperature. Since the photo sensor used is highly linear over the entire operating temperature range, the true temperature of the target can then be computed. Preliminary results indicate that true temperatures thus obtained are in excellent correlation with thermocouple measured temperatures.

  19. Simple microcalorimeter for measuring microgram samples at low temperatures

    NASA Astrophysics Data System (ADS)

    Doettinger-Zech, S. G.; Uhl, M.; Sisson, D. L.; Kapitulnik, A.

    2001-05-01

    An innovative microcalorimeter has been developed for measuring specific heat of very small microgram samples in the temperature range from 1.5 to 50 K and in magnetic fields up to 11 T. The device is built from a commercial sapphire temperature chip (Cernox), which is modified by means of standard microfabrication techniques and which is used as a sample holder, temperature sensor, and sample heater. Compared to existing microcalorimeters the simple design of our instrument allows a fabrication of the device in a few process steps by using facilities present in a standard laboratory clean room. As an illustrative example for the performance of our device, the specific heat of an underdoped (La1-xSrx)2CuO4 and CaRuO3 single crystal has been measured by means of the relaxation time method as well as the ac method.

  20. Rotating sample magnetometer for cryogenic temperatures and high magnetic fields

    NASA Astrophysics Data System (ADS)

    Eisterer, M.; Hengstberger, F.; Voutsinas, C. S.; Hörhager, N.; Sorta, S.; Hecher, J.; Weber, H. W.

    2011-06-01

    We report on the design and implementation of a rotating sample magnetometer (RSM) operating in the variable temperature insert (VTI) of a cryostat equipped with a high-field magnet. The limited space and the cryogenic temperatures impose the most critical design parameters: the small bore size of the magnet requires a very compact pick-up coil system and the low temperatures demand a very careful design of the bearings. Despite these difficulties the RSM achieves excellent resolution at high magnetic field sweep rates, exceeding that of a typical vibrating sample magnetometer by about a factor of ten. In addition the gas-flow cryostat and the high-field superconducting magnet provide a temperature and magnetic field range unprecedented for this type of magnetometer.

  1. Parametric models for samples of random functions

    SciTech Connect

    Grigoriu, M.

    2015-09-15

    A new class of parametric models, referred to as sample parametric models, is developed for random elements that match sample rather than the first two moments and/or other global properties of these elements. The models can be used to characterize, e.g., material properties at small scale in which case their samples represent microstructures of material specimens selected at random from a population. The samples of the proposed models are elements of finite-dimensional vector spaces spanned by samples, eigenfunctions of Karhunen–Loève (KL) representations, or modes of singular value decompositions (SVDs). The implementation of sample parametric models requires knowledge of the probability laws of target random elements. Numerical examples including stochastic processes and random fields are used to demonstrate the construction of sample parametric models, assess their accuracy, and illustrate how these models can be used to solve efficiently stochastic equations.

  2. Response of TGS ferroelectric samples to rapid temperature impulses

    NASA Astrophysics Data System (ADS)

    Trybus, M.; Proszak, W.; Woś, B.

    2013-11-01

    Tryglicine sulphate (TGS) is one of the most extensively studied ferroelectric materials, which undergoes second order phase transition and shows the pyroelectric effect. In our present experiments we study the electric properties of TGS, in relation to domain switching, observing the samples' response to controlled temperature pulses. The charge released in the processes of domain switching was previously studied under constant temperature growth. Our method allows us to observe the released pyroelectric charge in both the ferroelectric and paraelectric phases. To perform our experiment we designed new measurement software and constructed a novel thermostatic sample holder containing Peltier's cells as heating/cooling elements.

  3. Ultra sound absorption measurements in rock samples at low temperatures

    NASA Technical Reports Server (NTRS)

    Herminghaus, C.; Berckhemer, H.

    1974-01-01

    A new technique, comparable with the reverberation method in room acoustics, is described. It allows Q-measurements at rock samples of arbitrary shape in the frequency range of 50 to 600 kHz in vacuum (.1 mtorr) and at low temperatures (+20 to -180 C). The method was developed in particular to investigate rock samples under lunar conditions. Ultrasound absorption has been measured at volcanics, breccia, gabbros, feldspar and quartz of different grain size and texture yielding the following results: evacuation raises Q mainly through lowering the humidity in the rock. In a dry compact rock, the effect of evacuation is small. With decreasing temperature, Q generally increases. Between +20 and -30 C, Q does not change much. With further decrease of temperature in many cases distinct anomalies appear, where Q becomes frequency dependent.

  4. Modeling uncertainty: quicksand for water temperature modeling

    USGS Publications Warehouse

    Bartholow, John M.

    2003-01-01

    Uncertainty has been a hot topic relative to science generally, and modeling specifically. Modeling uncertainty comes in various forms: measured data, limited model domain, model parameter estimation, model structure, sensitivity to inputs, modelers themselves, and users of the results. This paper will address important components of uncertainty in modeling water temperatures, and discuss several areas that need attention as the modeling community grapples with how to incorporate uncertainty into modeling without getting stuck in the quicksand that prevents constructive contributions to policy making. The material, and in particular the reference, are meant to supplement the presentation given at this conference.

  5. Fast temperature spectrometer for samples under extreme conditions

    NASA Astrophysics Data System (ADS)

    Zhang, Dongzhou; Jackson, Jennifer M.; Zhao, Jiyong; Sturhahn, Wolfgang; Alp, E. Ercan; Toellner, Thomas S.; Hu, Michael Y.

    2015-01-01

    We have developed a multi-wavelength Fast Temperature Readout (FasTeR) spectrometer to capture a sample's transient temperature fluctuations, and reduce uncertainties in melting temperature determination. Without sacrificing accuracy, FasTeR features a fast readout rate (about 100 Hz), high sensitivity, large dynamic range, and a well-constrained focus. Complimenting a charge-coupled device spectrometer, FasTeR consists of an array of photomultiplier tubes and optical dichroic filters. The temperatures determined by FasTeR outside of the vicinity of melting are, generally, in good agreement with results from the charge-coupled device spectrometer. Near melting, FasTeR is capable of capturing transient temperature fluctuations, at least on the order of 300 K/s. A software tool, SIMFaster, is described and has been developed to simulate FasTeR and assess design configurations. FasTeR is especially suitable for temperature determinations that utilize ultra-fast techniques under extreme conditions. Working in parallel with the laser-heated diamond-anvil cell, synchrotron Mössbauer spectroscopy, and X-ray diffraction, we have applied the FasTeR spectrometer to measure the melting temperature of 57Fe0.9Ni0.1 at high pressure.

  6. Fast temperature spectrometer for samples under extreme conditions.

    PubMed

    Zhang, Dongzhou; Jackson, Jennifer M; Zhao, Jiyong; Sturhahn, Wolfgang; Alp, E Ercan; Toellner, Thomas S; Hu, Michael Y

    2015-01-01

    We have developed a multi-wavelength Fast Temperature Readout (FasTeR) spectrometer to capture a sample's transient temperature fluctuations, and reduce uncertainties in melting temperature determination. Without sacrificing accuracy, FasTeR features a fast readout rate (about 100 Hz), high sensitivity, large dynamic range, and a well-constrained focus. Complimenting a charge-coupled device spectrometer, FasTeR consists of an array of photomultiplier tubes and optical dichroic filters. The temperatures determined by FasTeR outside of the vicinity of melting are, generally, in good agreement with results from the charge-coupled device spectrometer. Near melting, FasTeR is capable of capturing transient temperature fluctuations, at least on the order of 300 K/s. A software tool, SIMFaster, is described and has been developed to simulate FasTeR and assess design configurations. FasTeR is especially suitable for temperature determinations that utilize ultra-fast techniques under extreme conditions. Working in parallel with the laser-heated diamond-anvil cell, synchrotron Mössbauer spectroscopy, and X-ray diffraction, we have applied the FasTeR spectrometer to measure the melting temperature of (57)Fe0.9Ni0.1 at high pressure. PMID:25638070

  7. Temperature data for phenological models.

    PubMed

    Snyder, R L; Spano, D; Duce, P; Cesaraccio, C

    2001-11-01

    In an arid environment, the effect of evaporation on energy balance can affect air temperature recordings and greatly impact on degree-day calculations. This is an important consideration when choosing a site or climate data for phenological models. To our knowledge, there is no literature showing the effect of the underlying surface and its fetch around a weather station on degree-day accumulations. In this paper, we present data to show that this is a serious consideration, and it can lead to dubious models. Microscale measurements of temperature and energy balance are presented to explain why the differences occur. For example, the effect of fetch of irrigated grass and wetting of bare soil around a weather station on diurnal temperature are reported. A 43-day experiment showed that temperature measured on the upwind edge of an irrigated grass area averaged 4% higher than temperatures recorded 200 m inside the grass field. When the single-triangle method was used with a 10 degrees C threshold and starting on May 19, the station on the upwind edge recorded 900 degree-days on June 28, whereas the interior station recorded 900 degree-days on July 1. Clearly, a difference in fetch can lead to big errors for large degree-day accumulations. Immediately after wetting, the temperature over a wet soil surface was similar to that measured over grass. However, the temperature over the soil increased more than that over the grass as the soil surface dried. Therefore, the observed difference between temperatures measured over bare soil and those over grass increases with longer periods between wettings. In most arid locations, measuring temperature over irrigated grass gives a lower mean annual temperature, resulting in lower annual cumulative degree-day values. This was verified by comparing measurements over grass with those over bare soil at several weather stations in a range of climates. To eliminate the effect of rainfall frequency, using temperature data collected

  8. Thermal modeling of core sampling in flammable gas waste tanks. Part 1: Push-mode sampling

    SciTech Connect

    Unal, C.; Stroh, K.; Pasamehmetoglu, K.O.

    1997-08-01

    The radioactive waste stored in underground storage tanks at Hanford site is routinely being sampled for waste characterization purposes. The push- and rotary-mode core sampling is one of the sampling methods employed. The waste includes mixtures of sodium nitrate and sodium nitrite with organic compounds that can produce violent exothermic reactions if heated above 160 C during core sampling. A self-propagating waste reaction would produce very high temperatures that eventually result in failure of the tank and radioactive material releases to environment. A two-dimensional thermal model based on a lumped finite volume analysis method is developed. The enthalpy of each node is calculated from the first law of thermodynamics. A flash temperature and effective contact area concept were introduced to account the interface temperature rise. No maximum temperature rise exceeding the critical value of 60 C was found in the cases studied for normal operating conditions. Several accident conditions are also examined. In these cases it was found that the maximum drill bit temperature remained below the critical reaction temperature as long as a 30 scfm purge flow is provided the push-mode drill bit during sampling in rotary mode. The failure to provide purge flow resulted in exceeding the limiting temperatures in a relatively short time.

  9. A low temperature scanning force microscope for biological samples

    SciTech Connect

    Gustafsson, M. G.L.

    1993-05-01

    An SFM has been constructed capable of operating at 143 K. Two contributions to SFM technology are described: a new method of fabricating tips, and new designs of SFM springs that significantly lower the noise level. The SFM has been used to image several biological samples (including collagen, ferritin, RNA, purple membrane) at 143 K and room temperature. No improvement in resolution resulted from 143 K operation; several possible reasons for this are discussed. Possibly sharper tips may help. The 143 K SFM will allow the study of new categories of samples, such as those prepared by freeze-frame, single molecules (temperature dependence of mechanical properties), etc. The SFM was used to cut single collagen molecules into segments with a precision of {le} 10 nm.

  10. Sampling Errors in Satellite-derived Infrared Sea Surface Temperatures

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Minnett, P. J.

    2014-12-01

    Sea Surface Temperature (SST) measured from satellites has been playing a crucial role in understanding geophysical phenomena. Generating SST Climate Data Records (CDRs) is considered to be the one that imposes the most stringent requirements on data accuracy. For infrared SSTs, sampling uncertainties caused by cloud presence and persistence generate errors. In addition, for sensors with narrow swaths, the swath gap will act as another sampling error source. This study is concerned with quantifying and understanding such sampling errors, which are important for SST CDR generation and for a wide range of satellite SST users. In order to quantify these errors, a reference Level 4 SST field (Multi-scale Ultra-high Resolution SST) is sampled by using realistic swath and cloud masks of Moderate Resolution Imaging Spectroradiometer (MODIS) and Advanced Along Track Scanning Radiometer (AATSR). Global and regional SST uncertainties are studied by assessing the sampling error at different temporal and spatial resolutions (7 spatial resolutions from 4 kilometers to 5.0° at the equator and 5 temporal resolutions from daily to monthly). Global annual and seasonal mean sampling errors are large in the high latitude regions, especially the Arctic, and have geographical distributions that are most likely related to stratus clouds occurrence and persistence. The region between 30°N and 30°S has smaller errors compared to higher latitudes, except for the Tropical Instability Wave area, where persistent negative errors are found. Important differences in sampling errors are also found between the broad and narrow swath scan patterns and between day and night fields. This is the first time that realistic magnitudes of the sampling errors are quantified. Future improvement in the accuracy of SST products will benefit from this quantification.

  11. Advances in downhole sampling of high temperature solutions

    SciTech Connect

    Bayhurst, G.K.; Janecky, D.R.

    1991-01-01

    A fluid sampler capable of sampling hot and/or deep wells has been developed at Los Alamos National Laboratory. In collaboration with Leutert Instruments, an off-the-shelf sampler design was modified to meet gas-tight and minimal chemical reactivity/contamination specifications for use in geothermal wells and deep ocean drillholes. This downhole sampler has been routinely used at temperatures up to 300{degrees}C and hole depths of greater than 5 km. We have tested this sampler in various continental wells, including Valles Caldera VC-2a and VC-2b, German KTB, Cajon Pass, and Yellowstone Y-10. Both the standard commercial and enhanced samplers have also been used to obtain samples from a range of depths in the Ocean Drilling Project's hole 504B and during recent mid-ocean ridge drilling efforts. The sampler has made it possible to collect samples at temperatures and conditions beyond the limits of other tools with the added advantage of chemical corrosion resistance.

  12. A Simple Model for Solidification of Undercooled Metallic Samples

    NASA Astrophysics Data System (ADS)

    Saleh, Abdala M.; Clemente, Roberto A.

    2004-06-01

    A simple model for reproducing temperature recalescence behaviour in spherical undercooled liquid metallic samples, undergoing crystallization transformations, is presented. The model is applied to constant heat extraction rate, uniform but time dependent temperature distribution inside the sample (even after the start of crystallization), a classical temperature dependent rate of nucleation (including contributions from different specific heats for different phases and also a catalytic factor to model the possibility of heterogeneous distributed impurities) and the solidified grain interface velocity is taken proportional to the temperature undercooling. Different assumptions are considered for the sample transformed fraction as function of the extended volume of nuclei, like the classical Kolmogoroff, Johnson-Mehl, Avrami one (corresponding to random distribution of nuclei), the Austin-Rickett one (corresponding to some kind of clusterized distribution) and also an empirical one corresponding to some ordering in the distribution of nuclei. As an example of application, a published experimental temperature curve for a zirconium sample in the electromagnetic containerless facility TEMPUS, during the 2nd International Microgravity Laboratory Mission in 1994, is modeled. Some thermo-physical parameters of interest for Zr are discussed.

  13. Functional Error Models to Accelerate Nested Sampling

    NASA Astrophysics Data System (ADS)

    Josset, L.; Elsheikh, A. H.; Demyanov, V.; Lunati, I.

    2014-12-01

    The main challenge in groundwater problems is the reliance on large numbers of unknown parameters with wide rage of associated uncertainties. To translate this uncertainty to quantities of interest (for instance the concentration of pollutant in a drinking well), a large number of forward flow simulations is required. To make the problem computationally tractable, Josset et al. (2013, 2014) introduced the concept of functional error models. It consists in two elements: a proxy model that is cheaper to evaluate than the full physics flow solver and an error model to account for the missing physics. The coupling of the proxy model and the error models provides reliable predictions that approximate the full physics model's responses. The error model is tailored to the problem at hand by building it for the question of interest. It follows a typical approach in machine learning where both the full physics and proxy models are evaluated for a training set (subset of realizations) and the set of responses is used to construct the error model using functional data analysis. Once the error model is devised, a prediction of the full physics response for a new geostatistical realization can be obtained by computing the proxy response and applying the error model. We propose the use of functional error models in a Bayesian inference context by combining it to the Nested Sampling (Skilling 2006; El Sheikh et al. 2013, 2014). Nested Sampling offers a mean to compute the Bayesian Evidence by transforming the multidimensional integral into a 1D integral. The algorithm is simple: starting with an active set of samples, at each iteration, the sample with the lowest likelihood is kept aside and replaced by a sample of higher likelihood. The main challenge is to find this sample of higher likelihood. We suggest a new approach: first the active set is sampled, both proxy and full physics models are run and the functional error model is build. Then, at each iteration of the Nested

  14. Tissue Sampling Guides for Porcine Biomedical Models.

    PubMed

    Albl, Barbara; Haesner, Serena; Braun-Reichhart, Christina; Streckel, Elisabeth; Renner, Simone; Seeliger, Frank; Wolf, Eckhard; Wanke, Rüdiger; Blutke, Andreas

    2016-04-01

    This article provides guidelines for organ and tissue sampling adapted to porcine animal models in translational medical research. Detailed protocols for the determination of sampling locations and numbers as well as recommendations on the orientation, size, and trimming direction of samples from ∼50 different porcine organs and tissues are provided in the Supplementary Material. The proposed sampling protocols include the generation of samples suitable for subsequent qualitative and quantitative analyses, including cryohistology, paraffin, and plastic histology; immunohistochemistry;in situhybridization; electron microscopy; and quantitative stereology as well as molecular analyses of DNA, RNA, proteins, metabolites, and electrolytes. With regard to the planned extent of sampling efforts, time, and personnel expenses, and dependent upon the scheduled analyses, different protocols are provided. These protocols are adjusted for (I) routine screenings, as used in general toxicity studies or in analyses of gene expression patterns or histopathological organ alterations, (II) advanced analyses of single organs/tissues, and (III) large-scale sampling procedures to be applied in biobank projects. Providing a robust reference for studies of porcine models, the described protocols will ensure the efficiency of sampling, the systematic recovery of high-quality samples representing the entire organ or tissue as well as the intra-/interstudy comparability and reproducibility of results. PMID:26883152

  15. High temperature furnace modeling and performance verifications

    NASA Technical Reports Server (NTRS)

    Smith, James E., Jr.

    1992-01-01

    Analytical, numerical, and experimental studies were performed on two classes of high temperature materials processing sources for their potential use as directional solidification furnaces. The research concentrated on a commercially available high temperature furnace using a zirconia ceramic tube as the heating element and an Arc Furnace based on a tube welder. The first objective was to assemble the zirconia furnace and construct parts needed to successfully perform experiments. The 2nd objective was to evaluate the zirconia furnace performance as a directional solidification furnace element. The 3rd objective was to establish a data base on materials used in the furnace construction, with particular emphasis on emissivities, transmissivities, and absorptivities as functions of wavelength and temperature. A 1-D and 2-D spectral radiation heat transfer model was developed for comparison with standard modeling techniques, and were used to predict wall and crucible temperatures. The 4th objective addressed the development of a SINDA model for the Arc Furnace and was used to design sample holders and to estimate cooling media temperatures for the steady state operation of the furnace. And, the 5th objective addressed the initial performance evaluation of the Arc Furnace and associated equipment for directional solidification. Results of these objectives are presented.

  16. New high temperature plasmas and sample introduction systems for analytical atomic emission and mass spectrometry

    SciTech Connect

    Montaser, A.

    1992-01-01

    New high temperature plasmas and new sample introduction systems are explored for rapid elemental and isotopic analysis of gases, solutions, and solids using mass spectrometry and atomic emission spectrometry. Emphasis was placed on atmospheric pressure He inductively coupled plasmas (ICP) suitable for atomization, excitation, and ionization of elements; simulation and computer modeling of plasma sources with potential for use in spectrochemical analysis; spectroscopic imaging and diagnostic studies of high temperature plasmas, particularly He ICP discharges; and development of new, low-cost sample introduction systems, and examination of techniques for probing the aerosols over a wide range. Refs., 14 figs. (DLC)

  17. Monte Carlo Sampling of Negative-temperature Plasma States

    SciTech Connect

    John A. Krommes; Sharadini Rath

    2002-07-19

    A Monte Carlo procedure is used to generate N-particle configurations compatible with two-temperature canonical equilibria in two dimensions, with particular attention to nonlinear plasma gyrokinetics. An unusual feature of the problem is the importance of a nontrivial probability density function R0(PHI), the probability of realizing a set {Phi} of Fourier amplitudes associated with an ensemble of uniformly distributed, independent particles. This quantity arises because the equilibrium distribution is specified in terms of {Phi}, whereas the sampling procedure naturally produces particles states gamma; {Phi} and gamma are related via a gyrokinetic Poisson equation, highly nonlinear in its dependence on gamma. Expansion and asymptotic methods are used to calculate R0(PHI) analytically; excellent agreement is found between the large-N asymptotic result and a direct numerical calculation. The algorithm is tested by successfully generating a variety of states of both positive and negative temperature, including ones in which either the longest- or shortest-wavelength modes are excited to relatively very large amplitudes.

  18. Beam Heating of Samples: Modeling and Verification. Part 2

    NASA Technical Reports Server (NTRS)

    Kazmierczak, Michael; Gopalakrishnan, Pradeep; Kumar, Raghav; Banerjee Rupak; Snell, Edward; Bellamy, Henry; Rosenbaum, Gerd; vanderWoerd, Mark

    2006-01-01

    Energy absorbed from the X-ray beam by the sample requires cooling by forced convection (i.e. cryostream) to minimize temperature increase and the damage caused to the sample by the X-ray heating. In this presentation we will first review the current theoretical models and recent studies in the literature, which predict the sample temperature rise for a given set of beam parameters. It should be noted that a common weakness of these previous studies is that none of them provide actual experimental confirmation. This situation is now remedied in our investigation where the problem of x-ray sample heating is taken up once more. We have theoretically investigated, and at the same time, in addition to the numerical computations, performed experiments to validate the predictions. We have modeled, analyzed and experimentally tested the temperature rise of a 1 mm diameter glass sphere (sample surrogate) exposed to an intense synchrotron X-ray beam, while it is being cooled in a uniform flow of nitrogen gas. The heat transfer, including external convection and internal heat conduction was theoretically modeled using CFD to predict the temperature variation in the sphere during cooling and while it was subjected to an undulator (ID sector 19) X-ray beam at the APS. The surface temperature of the sphere during the X-ray beam heating was measured using the infrared camera measurement technique described in a previous talk. The temperatures from the numerical predictions and experimental measurements are compared and discussed. Additional results are reported for the two different sphere sizes and for two different supporting pin orientations.

  19. Current Sharing Temperature Test and Simulation with GANDALF Code for ITER PF2 Conductor Sample

    NASA Astrophysics Data System (ADS)

    Li, Shaolei; Wu, Yu; Liu, Bo; Weng, Peide

    2011-10-01

    Cable-in-conduit conductor (CICC) conductor sample of the PF2 coil for ITER was tested in the SULTAN facility. According to the test results, the CICC conductor sample exhibited a stable performance regarding the current sharing temperature. Under the typical operational conditions of a current of 45 kA, a magnetic field of 4 T and a temperature of 5 K for PF2, the test result for the conductor current sharing temperature is 6.71 K, with a temperature margin of 1.71 K. For a comparison thermal-hydraulic analysis of the PF2 conductor was carried out using GANDALF code in a 1-D model, and the result is consistent with the test one.

  20. COAL SAMPLING AND ANALYSIS: METHODS AND MODELS

    EPA Science Inventory

    The report provides information on coal sampling and analysis (CSD) techniques and procedures and presents a statistical model for estimating SO2 emissions. (New Source Performance Standards for large coal-fired boilers and certain State Implementation Plans require operators to ...

  1. Mixture models for distance sampling detection functions.

    PubMed

    Miller, David L; Thomas, Len

    2015-01-01

    We present a new class of models for the detection function in distance sampling surveys of wildlife populations, based on finite mixtures of simple parametric key functions such as the half-normal. The models share many of the features of the widely-used "key function plus series adjustment" (K+A) formulation: they are flexible, produce plausible shapes with a small number of parameters, allow incorporation of covariates in addition to distance and can be fitted using maximum likelihood. One important advantage over the K+A approach is that the mixtures are automatically monotonic non-increasing and non-negative, so constrained optimization is not required to ensure distance sampling assumptions are honoured. We compare the mixture formulation to the K+A approach using simulations to evaluate its applicability in a wide set of challenging situations. We also re-analyze four previously problematic real-world case studies. We find mixtures outperform K+A methods in many cases, particularly spiked line transect data (i.e., where detectability drops rapidly at small distances) and larger sample sizes. We recommend that current standard model selection methods for distance sampling detection functions are extended to include mixture models in the candidate set. PMID:25793744

  2. Statistical analysis of temperature data sampled at Station-M in the Norwegian Sea

    NASA Astrophysics Data System (ADS)

    Lorentzen, Torbjørn

    2014-02-01

    The paper analyzes sea temperature data sampled at Station-M in the Norwegian Sea. The data cover the period 1948-2010. The following questions are addressed: What type of stochastic process characterizes the temperature series? Are there any changes or patterns which indicate climate change? Are there any characteristics in the data which can be linked to the shrinking sea-ice in the Arctic area? Can the series be modeled consistently and applied in forecasting of the future sea temperature? The paper applies the following methods: Augmented Dickey-Fuller tests for testing of unit-root and stationarity, ARIMA-models in univariate modeling, cointegration and error-correcting models are applied in estimating short- and long-term dynamics of non-stationary series, Granger-causality tests in analyzing the interaction pattern between the deep and upper layer temperatures, and simultaneous equation systems are applied in forecasting future temperature. The paper shows that temperature at 2000 m Granger-causes temperature at 150 m, and that the 2000 m series can represent an important information carrier of the long-term development of the sea temperature in the geographical area. Descriptive statistics shows that the temperature level has been on a positive trend since the beginning of the 1980s which is also measured in most of the oceans in the North Atlantic. The analysis shows that the temperature series are cointegrated which means they share the same long-term stochastic trend and they do not diverge too far from each other. The measured long-term temperature increase is one of the factors that can explain the shrinking summer sea-ice in the Arctic region. The analysis shows that there is a significant negative correlation between the shrinking sea ice and the sea temperature at Station-M. The paper shows that the temperature forecasts are conditioned on the properties of the stochastic processes, causality pattern between the variables and specification of model

  3. Annealed Importance Sampling for Neural Mass Models

    PubMed Central

    Penny, Will; Sengupta, Biswa

    2016-01-01

    Neural Mass Models provide a compact description of the dynamical activity of cell populations in neocortical regions. Moreover, models of regional activity can be connected together into networks, and inferences made about the strength of connections, using M/EEG data and Bayesian inference. To date, however, Bayesian methods have been largely restricted to the Variational Laplace (VL) algorithm which assumes that the posterior distribution is Gaussian and finds model parameters that are only locally optimal. This paper explores the use of Annealed Importance Sampling (AIS) to address these restrictions. We implement AIS using proposals derived from Langevin Monte Carlo (LMC) which uses local gradient and curvature information for efficient exploration of parameter space. In terms of the estimation of Bayes factors, VL and AIS agree about which model is best but report different degrees of belief. Additionally, AIS finds better model parameters and we find evidence of non-Gaussianity in their posterior distribution. PMID:26942606

  4. Annealed Importance Sampling for Neural Mass Models.

    PubMed

    Penny, Will; Sengupta, Biswa

    2016-03-01

    Neural Mass Models provide a compact description of the dynamical activity of cell populations in neocortical regions. Moreover, models of regional activity can be connected together into networks, and inferences made about the strength of connections, using M/EEG data and Bayesian inference. To date, however, Bayesian methods have been largely restricted to the Variational Laplace (VL) algorithm which assumes that the posterior distribution is Gaussian and finds model parameters that are only locally optimal. This paper explores the use of Annealed Importance Sampling (AIS) to address these restrictions. We implement AIS using proposals derived from Langevin Monte Carlo (LMC) which uses local gradient and curvature information for efficient exploration of parameter space. In terms of the estimation of Bayes factors, VL and AIS agree about which model is best but report different degrees of belief. Additionally, AIS finds better model parameters and we find evidence of non-Gaussianity in their posterior distribution. PMID:26942606

  5. Latin hypercube sampling with the SESOIL model

    SciTech Connect

    Hetrick, D.M.; Luxmoore, R.J.; Tharp, M.L.

    1994-09-01

    The seasonal soil compartment model SESOIL, a one-dimensional vertical transport code for chemicals in the unsaturated soil zone, has been coupled with the Monte Carlo computer code PRISM, which utilizes a Latin hypercube sampling method. Frequency distributions are assigned to each of 64 soil, chemical, and climate input variables for the SESOIL model, and these distributions are randomly sampled to generate N (200, for example) input data sets. The SESOIL model is run by PRISM for each set of input values, and the combined set of model variables and predictions are evaluated statistically by PRISM to summarize the relative influence of input variables on model results. Output frequency distributions for selected SESOIL components are produced. As an initial analysis and to illustrate the PRISM/SESOIL approach, input data were compiled for the model for three sites at different regions of the country (Oak Ridge, Tenn.; Fresno, Calif.; Fargo, N.D.). The chemical chosen for the analysis was trichloroethylene (TCE), which was initially loaded in the soil column at a 60- to 90-cm depth. The soil type at each site was assumed to be identical to the cherty silt loam at Oak Ridge; the only difference in the three data sets was the climatic data. Output distributions for TCE mass flux volatilized, TCE mass flux to groundwater, and residual TCE concentration in the lowest soil layer are vastly different for the three sites.

  6. EVALUATION OF STATIONARY SOURCE PARTICULATE MEASUREMENT METHODS. VOLUME III. GAS TEMPERATURE CONTROL DURING METHOD 5 SAMPLING

    EPA Science Inventory

    A study was conducted to measure changes in gas temperature along the length of a Method 5 sampling train due to variations in stack gas temperature, sampling rate, filter box temperature and method for controlling the probe heating element. For each run condition, temperatures w...

  7. Far infrared reflectance of sintered nickel manganite samples for negative temperature coefficient thermistors

    SciTech Connect

    Nikolic, M.V. . E-mail: maria@mi.sanu.ac.yu; Paraskevopoulos, K.M.; Aleksic, O.S.; Zorba, T.T.; Savic, S.M.; Lukovic, D.T.

    2007-08-07

    Single phase complex spinel (Mn, Ni, Co, Fe){sub 3}O{sub 4} samples were sintered at 1050, 1200 and 1300 deg. C for 30 min and at 1200 deg. C for 120 min. Morphological changes of the obtained samples with the sintering temperature and time were analyzed by X-ray diffraction and scanning electron microscope (SEM). Room temperature far infrared reflectivity spectra for all samples were measured in the frequency range between 50 and 1200 cm{sup -1}. The obtained spectra for all samples showed the presence of the same oscillators, but their intensities increased with the sintering temperature and time in correlation with the increase in sample density and microstructure changes during sintering. The measured spectra were numerically analyzed using the Kramers-Kroenig method and the four-parameter model of coupled oscillators. Optical modes were calculated for six observed ionic oscillators belonging to the spinel structure of (Mn, Ni, Co, Fe){sub 3}O{sub 4} of which four were strong and two were weak.

  8. Bayesian nonparametric models for ranked set sampling.

    PubMed

    Gemayel, Nader; Stasny, Elizabeth A; Wolfe, Douglas A

    2015-04-01

    Ranked set sampling (RSS) is a data collection technique that combines measurement with judgment ranking for statistical inference. This paper lays out a formal and natural Bayesian framework for RSS that is analogous to its frequentist justification, and that does not require the assumption of perfect ranking or use of any imperfect ranking models. Prior beliefs about the judgment order statistic distributions and their interdependence are embodied by a nonparametric prior distribution. Posterior inference is carried out by means of Markov chain Monte Carlo techniques, and yields estimators of the judgment order statistic distributions (and of functionals of those distributions). PMID:25326663

  9. Fast temperature spectrometer for samples under extreme conditions

    SciTech Connect

    Zhang, Dongzhou; Jackson, Jennifer M.; Sturhahn, Wolfgang; Zhao, Jiyong; Alp, E. Ercan; Toellner, Thomas S.; Hu, Michael Y.

    2015-01-15

    We have developed a multi-wavelength Fast Temperature Readout (FasTeR) spectrometer to capture a sample’s transient temperature fluctuations, and reduce uncertainties in melting temperature determination. Without sacrificing accuracy, FasTeR features a fast readout rate (about 100 Hz), high sensitivity, large dynamic range, and a well-constrained focus. Complimenting a charge-coupled device spectrometer, FasTeR consists of an array of photomultiplier tubes and optical dichroic filters. The temperatures determined by FasTeR outside of the vicinity of melting are, generally, in good agreement with results from the charge-coupled device spectrometer. Near melting, FasTeR is capable of capturing transient temperature fluctuations, at least on the order of 300 K/s. A software tool, SIMFaster, is described and has been developed to simulate FasTeR and assess design configurations. FasTeR is especially suitable for temperature determinations that utilize ultra-fast techniques under extreme conditions. Working in parallel with the laser-heated diamond-anvil cell, synchrotron Mössbauer spectroscopy, and X-ray diffraction, we have applied the FasTeR spectrometer to measure the melting temperature of {sup 57}Fe{sub 0.9}Ni{sub 0.1} at high pressure.

  10. Finite-size Scaling Considerations on the Ground State Microcanonical Temperature in Entropic Sampling Simulations

    NASA Astrophysics Data System (ADS)

    Caparica, A. A.; DaSilva, Cláudio J.

    2015-12-01

    In this work, we discuss the behavior of the microcanonical temperature {partial S(E)}/{partial E} obtained by means of numerical entropic sampling studies. It is observed that in almost all cases, the slope of the logarithm of the density of states S( E) is not infinite in the ground state, since as expected it should be directly related to the inverse temperature {1}/{T}. Here, we show that these finite slopes are in fact due to finite-size effects and we propose an analytic expression aln( bL) for the behavior of {\\varDelta S}/{\\varDelta E} when L→ ∞. To test this idea, we use three distinct two-dimensional square lattice models presenting second-order phase transitions. We calculated by exact means the parameters a and b for the two-states Ising model and for the q = 3 and 4 states Potts model and compared with the results obtained by entropic sampling simulations. We found an excellent agreement between exact and numerical values. We argue that this new set of parameters a and b represents an interesting novel issue of investigation in entropic sampling studies for different models.

  11. Thermal modeling of core sampling in flammable gas waste tanks. Part 2: Rotary-mode sampling

    SciTech Connect

    Unal, C.; Poston, D.; Pasamehmetoglu, K.O.; Witwer, K.S.

    1997-08-01

    The radioactive waste stored in underground storage tanks at Hanford site includes mixtures of sodium nitrate and sodium nitrite with organic compounds. The waste can produce undesired violent exothermic reactions when heated locally during the rotary-mode sampling. Experiments are performed varying the downward force at a maximum rotational speed of 55 rpm and minimum nitrogen purge flow of 30 scfm. The rotary drill bit teeth-face temperatures are measured. The waste is simulated with a low thermal conductivity hard material, pumice blocks. A torque meter is used to determine the energy provided to the drill string. The exhaust air-chip temperature as well as drill string and drill bit temperatures and other key operating parameters were recorded. A two-dimensional thermal model is developed. The safe operating conditions were determined for normal operating conditions. A downward force of 750 at 55 rpm and 30 scfm nitrogen purge flow was found to yield acceptable substrate temperatures. The model predicted experimental results reasonably well. Therefore, it could be used to simulate abnormal conditions to develop procedures for safe operations.

  12. Determining Curie temperature of (Ga,Mn)As samples based on electrical transport measurements: Low Curie temperature case

    NASA Astrophysics Data System (ADS)

    Kwiatkowski, Adam; Gryglas-Borysiewicz, Marta; Juszyński, Piotr; Przybytek, Jacek; Sawicki, Maciej; Sadowski, Janusz; Wasik, Dariusz; Baj, Michał

    2016-06-01

    In this paper, we show that the widely accepted method of the determination of Curie temperature (TC) in (Ga,Mn)As samples, based on the position of the peak in the temperature derivative of the resistivity, completely fails in the case of non-metallic and low-TC unannealed samples. In this case, we propose an alternative method, also based on electric transport measurements, which exploits temperature dependence of the second derivative of the resistivity upon magnetic field.

  13. Modeling maximum daily temperature using a varying coefficient regression model

    NASA Astrophysics Data System (ADS)

    Li, Han; Deng, Xinwei; Kim, Dong-Yun; Smith, Eric P.

    2014-04-01

    Relationships between stream water and air temperatures are often modeled using linear or nonlinear regression methods. Despite a strong relationship between water and air temperatures and a variety of models that are effective for data summarized on a weekly basis, such models did not yield consistently good predictions for summaries such as daily maximum temperature. A good predictive model for daily maximum temperature is required because daily maximum temperature is an important measure for predicting survival of temperature sensitive fish. To appropriately model the strong relationship between water and air temperatures at a daily time step, it is important to incorporate information related to the time of the year into the modeling. In this work, a time-varying coefficient model is used to study the relationship between air temperature and water temperature. The time-varying coefficient model enables dynamic modeling of the relationship, and can be used to understand how the air-water temperature relationship varies over time. The proposed model is applied to 10 streams in Maryland, West Virginia, Virginia, North Carolina, and Georgia using daily maximum temperatures. It provides a better fit and better predictions than those produced by a simple linear regression model or a nonlinear logistic model.

  14. Estimation of Surface Heat Flux and Surface Temperature during Inverse Heat Conduction under Varying Spray Parameters and Sample Initial Temperature

    PubMed Central

    Aamir, Muhammad; Liao, Qiang; Zhu, Xun; Aqeel-ur-Rehman; Wang, Hong

    2014-01-01

    An experimental study was carried out to investigate the effects of inlet pressure, sample thickness, initial sample temperature, and temperature sensor location on the surface heat flux, surface temperature, and surface ultrafast cooling rate using stainless steel samples of diameter 27 mm and thickness (mm) 8.5, 13, 17.5, and 22, respectively. Inlet pressure was varied from 0.2 MPa to 1.8 MPa, while sample initial temperature varied from 600°C to 900°C. Beck's sequential function specification method was utilized to estimate surface heat flux and surface temperature. Inlet pressure has a positive effect on surface heat flux (SHF) within a critical value of pressure. Thickness of the sample affects the maximum achieved SHF negatively. Surface heat flux as high as 0.4024 MW/m2 was estimated for a thickness of 8.5 mm. Insulation effects of vapor film become apparent in the sample initial temperature range of 900°C causing reduction in surface heat flux and cooling rate of the sample. A sensor location near to quenched surface is found to be a better choice to visualize the effects of spray parameters on surface heat flux and surface temperature. Cooling rate showed a profound increase for an inlet pressure of 0.8 MPa. PMID:24977219

  15. Estimation of surface heat flux and surface temperature during inverse heat conduction under varying spray parameters and sample initial temperature.

    PubMed

    Aamir, Muhammad; Liao, Qiang; Zhu, Xun; Aqeel-ur-Rehman; Wang, Hong; Zubair, Muhammad

    2014-01-01

    An experimental study was carried out to investigate the effects of inlet pressure, sample thickness, initial sample temperature, and temperature sensor location on the surface heat flux, surface temperature, and surface ultrafast cooling rate using stainless steel samples of diameter 27 mm and thickness (mm) 8.5, 13, 17.5, and 22, respectively. Inlet pressure was varied from 0.2 MPa to 1.8 MPa, while sample initial temperature varied from 600°C to 900°C. Beck's sequential function specification method was utilized to estimate surface heat flux and surface temperature. Inlet pressure has a positive effect on surface heat flux (SHF) within a critical value of pressure. Thickness of the sample affects the maximum achieved SHF negatively. Surface heat flux as high as 0.4024 MW/m(2) was estimated for a thickness of 8.5 mm. Insulation effects of vapor film become apparent in the sample initial temperature range of 900°C causing reduction in surface heat flux and cooling rate of the sample. A sensor location near to quenched surface is found to be a better choice to visualize the effects of spray parameters on surface heat flux and surface temperature. Cooling rate showed a profound increase for an inlet pressure of 0.8 MPa. PMID:24977219

  16. LAKE WATER TEMPERATURE SIMULATION MODEL

    EPA Science Inventory

    Functional relationships to describe surface wind mixing, vertical turbulent diffusion, convective heat transfer, and radiation penetration based on data from lakes in Minnesota have been developed. hese relationships have been introduced by regressing model parameters found eith...

  17. Modeling monthly mean air temperature for Brazil

    NASA Astrophysics Data System (ADS)

    Alvares, Clayton Alcarde; Stape, José Luiz; Sentelhas, Paulo Cesar; de Moraes Gonçalves, José Leonardo

    2013-08-01

    Air temperature is one of the main weather variables influencing agriculture around the world. Its availability, however, is a concern, mainly in Brazil where the weather stations are more concentrated on the coastal regions of the country. Therefore, the present study had as an objective to develop models for estimating monthly and annual mean air temperature for the Brazilian territory using multiple regression and geographic information system techniques. Temperature data from 2,400 stations distributed across the Brazilian territory were used, 1,800 to develop the equations and 600 for validating them, as well as their geographical coordinates and altitude as independent variables for the models. A total of 39 models were developed, relating the dependent variables maximum, mean, and minimum air temperatures (monthly and annual) to the independent variables latitude, longitude, altitude, and their combinations. All regression models were statistically significant ( α ≤ 0.01). The monthly and annual temperature models presented determination coefficients between 0.54 and 0.96. We obtained an overall spatial correlation higher than 0.9 between the models proposed and the 16 major models already published for some Brazilian regions, considering a total of 3.67 × 108 pixels evaluated. Our national temperature models are recommended to predict air temperature in all Brazilian territories.

  18. Effects of High-frequency Wind Sampling on Simulated Mixed Layer Depth and Upper Ocean Temperature

    NASA Technical Reports Server (NTRS)

    Lee, Tong; Liu, W. Timothy

    2005-01-01

    Effects of high-frequency wind sampling on a near-global ocean model are studied by forcing the model with a 12 hourly averaged wind product and its 24 hourly subsamples in separate experiments. The differences in mixed layer depth and sea surface temperature resulting from these experiments are examined, and the underlying physical processes are investigated. The 24 hourly subsampling not only reduces the high-frequency variability of the wind but also affects the annual mean wind because of aliasing. While the former effect largely impacts mid- to high-latitude oceans, the latter primarily affects tropical and coastal oceans. At mid- to high-latitude regions the subsampled wind results in a shallower mixed layer and higher sea surface temperature because of reduced vertical mixing associated with weaker high-frequency wind. In tropical and coastal regions, however, the change in upper ocean structure due to the wind subsampling is primarily caused by the difference in advection resulting from aliased annual mean wind, which varies with the subsampling time. The results of the study indicate a need for more frequent sampling of satellite wind measurement and have implications for data assimilation in terms of identifying the nature of model errors.

  19. On high-resolution sampling of short ice cores: Dating and temperature information recovery from Antarctic Peninsula virtual cores

    NASA Astrophysics Data System (ADS)

    Sime, Louise C.; Lang, Nicola; Thomas, Elizabeth R.; Benton, Ailsa K.; Mulvaney, Robert

    2011-10-01

    Recent developments in ice melter systems and continuous flow analysis (CFA) techniques now allow higher-resolution ice core analysis. Here, we present a new method to aid interpretation of high-resolution ice core stable water isotope records. Using a set of simple isotopic recording and postdepositional assumptions, the European Centre for Medium-Range Weather Forecasts' 40 year reanalysis time series of temperature and precipitation are converted to "virtual core" depth series across the Antarctic Peninsula, helping us to understand what information can be gleaned from the CFA high-resolution observations. Virtual core temperatures are transferred onto time using three different depth-age transfer assumptions: (1) a perfect depth-age model, (2) a depth-age model constructed from single or dual annual photochemical tie points, and (3) a cross-dated depth-age model. Comparing the sampled temperatures on the various depth-age models with the original time series allows quantification of the effect of ice core sample resolution and dating. We show that accurate annual layer count depth-age models should allow some subseasonal temperature anomalies to be recovered using a sample resolution of around 40 mm, or 10-20 samples per year. Seasonal temperature anomalies may be recovered using sample lengths closer to 60 mm, or about 7-14 samples per year. These results tend to confirm the value of current CFA ice core sampling strategies and indicate that it should be possible to recover about a third of subannual (but not synoptic) temperature anomaly information from annually "layer-counted" peninsula ice cores.

  20. Modeling daily average stream temperature from air temperature and watershed area

    NASA Astrophysics Data System (ADS)

    Butler, N. L.; Hunt, J. R.

    2012-12-01

    Habitat restoration efforts within watersheds require spatial and temporal estimates of water temperature for aquatic species especially species that migrate within watersheds at different life stages. Monitoring programs are not able to fully sample all aquatic environments within watersheds under the extreme conditions that determine long-term habitat viability. Under these circumstances a combination of selective monitoring and modeling are required for predicting future geospatial and temporal conditions. This study describes a model that is broadly applicable to different watersheds while using readily available regional air temperature data. Daily water temperature data from thirty-eight gauges with drainage areas from 2 km2 to 2000 km2 in the Sonoma Valley, Napa Valley, and Russian River Valley in California were used to develop, calibrate, and test a stream temperature model. Air temperature data from seven NOAA gauges provided the daily maximum and minimum air temperatures. The model was developed and calibrated using five years of data from the Sonoma Valley at ten water temperature gauges and a NOAA air temperature gauge. The daily average stream temperatures within this watershed were bounded by the preceding maximum and minimum air temperatures with smaller upstream watersheds being more dependent on the minimum air temperature than maximum air temperature. The model assumed a linear dependence on maximum and minimum air temperature with a weighting factor dependent on upstream area determined by error minimization using observed data. Fitted minimum air temperature weighting factors were consistent over all five years of data for each gauge, and they ranged from 0.75 for upstream drainage areas less than 2 km2 to 0.45 for upstream drainage areas greater than 100 km2. For the calibration data sets within the Sonoma Valley, the average error between the model estimated daily water temperature and the observed water temperature data ranged from 0.7

  1. Effect of the Target Motion Sampling Temperature Treatment Method on the Statistics and Performance

    NASA Astrophysics Data System (ADS)

    Viitanen, Tuomas; Leppänen, Jaakko

    2014-06-01

    Target Motion Sampling (TMS) is a stochastic on-the-fly temperature treatment technique that is being developed as a part of the Monte Carlo reactor physics code Serpent. The method provides for modeling of arbitrary temperatures in continuous-energy Monte Carlo tracking routines with only one set of cross sections stored in the computer memory. Previously, only the performance of the TMS method in terms of CPU time per transported neutron has been discussed. Since the effective cross sections are not calculated at any point of a transport simulation with TMS, reaction rate estimators must be scored using sampled cross sections, which is expected to increase the variances and, consequently, to decrease the figures-of-merit. This paper examines the effects of the TMS on the statistics and performance in practical calculations involving reaction rate estimation with collision estimators. Against all expectations it turned out that the usage of sampled response values has no practical effect on the performance of reaction rate estimators when using TMS with elevated basis cross section temperatures (EBT), i.e. the usual way. With 0 Kelvin cross sections a significant increase in the variances of capture rate estimators was observed right below the energy region of unresolved resonances, but at these energies the figures-of-merit could be increased using a simple resampling technique to decrease the variances of the responses. It was, however, noticed that the usage of the TMS method increases the statistical deviances of all estimators, including the flux estimator, by tens of percents in the vicinity of very strong resonances. This effect is actually not related to the usage of sampled responses, but is instead an inherent property of the TMS tracking method and concerns both EBT and 0 K calculations.

  2. The X-ray luminosity temperature relation of a complete sample of low mass galaxy clusters

    NASA Astrophysics Data System (ADS)

    Zou, S.; Maughan, B. J.; Giles, P. A.; Vikhlinin, A.; Pacaud, F.; Burenin, R.; Hornstrup, A.

    2016-08-01

    We present Chandra observations of 23 galaxy groups and low-mass galaxy clusters at 0.03 < z < 0.15 with a median temperature of ˜2 KeV. The sample is a statistically complete flux-limited subset of the 400 deg2 survey. We investigated the scaling relation between X-ray luminosity (L) and temperature (T), taking selection biases fully into account. The logarithmic slope of the bolometric L - T relation was found to be 3.29 ± 0.33, consistent with values typically found for samples of more massive clusters. In combination with other recent studies of the L - T relation we show that there is no evidence for the slope, normalisation, or scatter of the L - T relation of galaxy groups being different than that of massive clusters. The exception to this is that in the special case of the most relaxed systems, the slope of the core-excised L - T relation appears to steepen from the self-similar value found for massive clusters to a steeper slope for the lower mass sample studied here. Thanks to our rigorous treatment of selection biases, these measurements provide a robust reference against which to compare predictions of models of the impact of feedback on the X-ray properties of galaxy groups.

  3. Method and apparatus for transport, introduction, atomization and excitation of emission spectrum for quantitative analysis of high temperature gas sample streams containing vapor and particulates without degradation of sample stream temperature

    DOEpatents

    Eckels, David E.; Hass, William J.

    1989-05-30

    A sample transport, sample introduction, and flame excitation system for spectrometric analysis of high temperature gas streams which eliminates degradation of the sample stream by condensation losses.

  4. 40 CFR 53.57 - Test for filter temperature control during sampling and post-sampling periods.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... (40 CFR part 50, appendix L, figure L-30) or equivalent adaptor to facilitate measurement of sampler... recommended. (6) Sample filter or filters, as specified in section 6 of 40 CFR part 50, appendix L. (d... 40 Protection of Environment 6 2014-07-01 2014-07-01 false Test for filter temperature...

  5. 40 CFR 53.57 - Test for filter temperature control during sampling and post-sampling periods.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... (40 CFR part 50, appendix L, figure L-30) or equivalent adaptor to facilitate measurement of sampler... recommended. (6) Sample filter or filters, as specified in section 6 of 40 CFR part 50, appendix L. (d... 40 Protection of Environment 6 2013-07-01 2013-07-01 false Test for filter temperature...

  6. AN EVALUATION OF PERSONAL SAMPLING PUMPS IN SUB-ZERO TEMPERATURES

    EPA Science Inventory

    Personal sampling pumps suitable for industrial hygiene surveys were evaluated to discover their characteristics as a function of temperature for temperatures between 25 and -50C. The pumps evaluated were significantly influenced by low temperatures. In general, most provided a s...

  7. Modulated photothermal radiometry applied to semitransparent samples: Models and experiments

    NASA Astrophysics Data System (ADS)

    André, S.; Rémy, B.; Maillet, D.; Degiovanni, A.; Serra, J.-J.

    2004-09-01

    Mathematical modeling is presented of the combined conductive and radiative heat transfer occurring in a semitransparent material (STM) subjected to a periodic heat flux. The models rely on the quadrupole method, which is a very powerful tool to obtain analytical solutions in the Fourier or Laplace domain. Photoacoustic or photothermal radiometry techniques are reviewed. Two groups of methods are discussed depending on whether the sample has natural or opaque interfaces to simulate radiative exchanges with the surroundings. The metrological problem of measuring the phonic thermal diffusivity of semitransparent materials is investigated. Theoretical simulations are given. They explain some typical features of the phase-lag signal of temperature responses. Experimental measurements on pure silica validate the results and prove that these methods are efficient for the thermal characterization of STM.

  8. SAMPLING SYSTEM EVALUATION FOR HIGH-TEMPERATURE, HIGH-PRESSURE PROCESSES

    EPA Science Inventory

    The report describes a sampling system designed for the high temperatures and high pressures found in pressurized fluidized-bed combustors (PFBC). The system uses an extractive sampling approach, withdrawing samples from the process stream for complete analysis of particulate siz...

  9. Measurement of temperature and temperature gradient in millimeter samples by chlorine NQR

    NASA Astrophysics Data System (ADS)

    Lužnik, Janko; Pirnat, Janez; Trontelj, Zvonko

    2009-09-01

    A mini-thermometer based on the 35Cl nuclear quadrupole resonance (NQR) frequency temperature dependence in the chlorates KClO3 and NaClO3 was built and successfully tested by measuring temperature and temperature gradient at 77 K and higher in about 100 mm3 active volume of a mini Joule-Thomson refrigerator. In the design of the tank-circuit coil, an array of small coils connected in series enabled us (a) to achieve a suitable ratio of inductance to capacity in the NQR spectrometer input tank circuit, (b) to use a single crystal of KClO3 or NaClO3 (of 1-2 mm3 size) in one coil as a mini-thermometer with a resolution of 0.03 K and (c) to construct a system for measuring temperature gradients when the spatial coordinates of each chlorate single crystal within an individual coil are known.

  10. Factors affecting quality of temperature models for the pre-appearance interval of forensically useful insects.

    PubMed

    Matuszewski, Szymon; Mądra, Anna

    2015-02-01

    In the case of many forensically important insects an interval preceding appearance of an insect stage on a corpse (called the pre-appearance interval or PAI) is strongly temperature-dependent. Accordingly, it was proposed to estimate PAI from temperature by using temperature models for PAI of particular insect species and temperature data specific for a given case. The quality of temperature models for PAI depends on the protocols for PAI field studies. In this article we analyze effects of sampling frequency and techniques, temperature data, as well as the size of a sample on the quality of PAI models. Models were created by using data from a largely replicated PAI field study, and their performance in estimation was tested with external body of PAI data. It was found that low frequency of insect sampling distinctly deteriorated temperature models for PAI. The effect of sampling techniques was clearly smaller. Temperature data from local weather station gave models of poor quality, however their retrospective correction clearly improved the models. Most importantly, current results demonstrate that sample size in PAI field studies may be substantially reduced, with no model deterioration. Samples consisting of 11-14 carcasses gave models of high quality, as long as the whole range of relevant temperatures was studied. Moreover, it was found that carcasses exposed in forests and carcasses exposed in early spring are particularly important, as they ensure that PAI data is collected at low temperatures. A preliminary best practice model for PAI field studies is given. PMID:25541074

  11. Temperature dependence of standard model CP violation.

    PubMed

    Brauner, Tomáš; Taanila, Olli; Tranberg, Anders; Vuorinen, Aleksi

    2012-01-27

    We analyze the temperature dependence of CP violation effects in the standard model by determining the effective action of its bosonic fields, obtained after integrating out the fermions from the theory and performing a covariant gradient expansion. We find nonvanishing CP violating terms starting at the sixth order of the expansion, albeit only in the C-odd-P-even sector, with coefficients that depend on quark masses, Cabibbo-Kobayashi-Maskawa matrix elements, temperature and the magnitude of the Higgs field. The CP violating effects are observed to decrease rapidly with temperature, which has important implications for the generation of a matter-antimatter asymmetry in the early Universe. Our results suggest that the cold electroweak baryogenesis scenario may be viable within the standard model, provided the electroweak transition temperature is at most of order 1 GeV. PMID:22400822

  12. Model for superconductivity at any temperature

    NASA Astrophysics Data System (ADS)

    Anber, Mohamed M.; Burnier, Yannis; Sabancilar, Eray; Shaposhnikov, Mikhail

    2016-01-01

    We construct a 2 +1 dimensional model that sustains superconductivity at all temperatures. This is achieved by introducing a Chern-Simons mixing term between two Abelian gauge fields A and Z . The superfluid is described by a complex scalar charged under Z , whereas a sufficiently strong magnetic field of A forces the superconducting condensate to form at all temperatures. In fact, at finite temperature, the theory exhibits Berezinsky-Kosterlitz-Thouless phase transition due to proliferation of topological vortices admitted by our construction. However, the critical temperature is proportional to the magnetic field of A , and thus, the phase transition can be postponed to high temperatures by increasing the strength of the magnetic field.

  13. Pre-analytical sample quality: metabolite ratios as an intrinsic marker for prolonged room temperature exposure of serum samples.

    PubMed

    Anton, Gabriele; Wilson, Rory; Yu, Zhong-Hao; Prehn, Cornelia; Zukunft, Sven; Adamski, Jerzy; Heier, Margit; Meisinger, Christa; Römisch-Margl, Werner; Wang-Sattler, Rui; Hveem, Kristian; Wolfenbuttel, Bruce; Peters, Annette; Kastenmüller, Gabi; Waldenberger, Melanie

    2015-01-01

    Advances in the "omics" field bring about the need for a high number of good quality samples. Many omics studies take advantage of biobanked samples to meet this need. Most of the laboratory errors occur in the pre-analytical phase. Therefore evidence-based standard operating procedures for the pre-analytical phase as well as markers to distinguish between 'good' and 'bad' quality samples taking into account the desired downstream analysis are urgently needed. We studied concentration changes of metabolites in serum samples due to pre-storage handling conditions as well as due to repeated freeze-thaw cycles. We collected fasting serum samples and subjected aliquots to up to four freeze-thaw cycles and to pre-storage handling delays of 12, 24 and 36 hours at room temperature (RT) and on wet and dry ice. For each treated aliquot, we quantified 127 metabolites through a targeted metabolomics approach. We found a clear signature of degradation in samples kept at RT. Storage on wet ice led to less pronounced concentration changes. 24 metabolites showed significant concentration changes at RT. In 22 of these, changes were already visible after only 12 hours of storage delay. Especially pronounced were increases in lysophosphatidylcholines and decreases in phosphatidylcholines. We showed that the ratio between the concentrations of these molecule classes could serve as a measure to distinguish between 'good' and 'bad' quality samples in our study. In contrast, we found quite stable metabolite concentrations during up to four freeze-thaw cycles. We concluded that pre-analytical RT handling of serum samples should be strictly avoided and serum samples should always be handled on wet ice or in cooling devices after centrifugation. Moreover, serum samples should be frozen at or below -80°C as soon as possible after centrifugation. PMID:25823017

  14. Pre-Analytical Sample Quality: Metabolite Ratios as an Intrinsic Marker for Prolonged Room Temperature Exposure of Serum Samples

    PubMed Central

    Anton, Gabriele; Wilson, Rory; Yu, Zhong-hao; Prehn, Cornelia; Zukunft, Sven; Adamski, Jerzy; Heier, Margit; Meisinger, Christa; Römisch-Margl, Werner; Wang-Sattler, Rui; Hveem, Kristian; Wolfenbuttel, Bruce; Peters, Annette; Kastenmüller, Gabi; Waldenberger, Melanie

    2015-01-01

    Advances in the “omics” field bring about the need for a high number of good quality samples. Many omics studies take advantage of biobanked samples to meet this need. Most of the laboratory errors occur in the pre-analytical phase. Therefore evidence-based standard operating procedures for the pre-analytical phase as well as markers to distinguish between ‘good’ and ‘bad’ quality samples taking into account the desired downstream analysis are urgently needed. We studied concentration changes of metabolites in serum samples due to pre-storage handling conditions as well as due to repeated freeze-thaw cycles. We collected fasting serum samples and subjected aliquots to up to four freeze-thaw cycles and to pre-storage handling delays of 12, 24 and 36 hours at room temperature (RT) and on wet and dry ice. For each treated aliquot, we quantified 127 metabolites through a targeted metabolomics approach. We found a clear signature of degradation in samples kept at RT. Storage on wet ice led to less pronounced concentration changes. 24 metabolites showed significant concentration changes at RT. In 22 of these, changes were already visible after only 12 hours of storage delay. Especially pronounced were increases in lysophosphatidylcholines and decreases in phosphatidylcholines. We showed that the ratio between the concentrations of these molecule classes could serve as a measure to distinguish between ‘good’ and ‘bad’ quality samples in our study. In contrast, we found quite stable metabolite concentrations during up to four freeze-thaw cycles. We concluded that pre-analytical RT handling of serum samples should be strictly avoided and serum samples should always be handled on wet ice or in cooling devices after centrifugation. Moreover, serum samples should be frozen at or below -80°C as soon as possible after centrifugation. PMID:25823017

  15. Global modeling of fresh surface water temperature

    NASA Astrophysics Data System (ADS)

    Bierkens, M. F.; Eikelboom, T.; van Vliet, M. T.; Van Beek, L. P.

    2011-12-01

    Temperature determines a range of water physical properties, the solubility of oxygen and other gases and acts as a strong control on fresh water biogeochemistry, influencing chemical reaction rates, phytoplankton and zooplankton composition and the presence or absence of pathogens. Thus, in freshwater ecosystems the thermal regime affects the geographical distribution of aquatic species through their growth and metabolism, tolerance to parasites, diseases and pollution and life history. Compared to statistical approaches, physically-based models of surface water temperature have the advantage that they are robust in light of changes in flow regime, river morphology, radiation balance and upstream hydrology. Such models are therefore better suited for projecting the effects of global change on water temperature. Till now, physically-based models have only been applied to well-defined fresh water bodies of limited size (e.g., lakes or stream segments), where the numerous parameters can be measured or otherwise established, whereas attempts to model water temperature over larger scales has thus far been limited to regression type of models. Here, we present a first attempt to apply a physically-based model of global fresh surface water temperature. The model adds a surface water energy balance to river discharge modelled by the global hydrological model PCR-GLOBWB. In addition to advection of energy from direct precipitation, runoff and lateral exchange along the drainage network, energy is exchanged between the water body and the atmosphere by short and long-wave radiation and sensible and latent heat fluxes. Also included are ice-formation and its effect on heat storage and river hydraulics. We used the coupled surface water and energy balance model to simulate global fresh surface water temperature at daily time steps on a 0.5x0.5 degree grid for the period 1970-2000. Meteorological forcing was obtained from the CRU data set, downscaled to daily values with ECMWF

  16. Temperature dependence on the pesticide sampling rate of polar organic chemical integrative samplers (POCIS).

    PubMed

    Yabuki, Yoshinori; Nagai, Takashi; Inao, Keiya; Ono, Junko; Aiko, Nobuyuki; Ohtsuka, Nobutoshi; Tanaka, Hitoshi; Tanimori, Shinji

    2016-10-01

    Laboratory experiments were performed to determine the sampling rates of pesticides for the polar organic chemical integrative samplers (POCIS) used in Japan. The concentrations of pesticides in aquatic environments were estimated from the accumulated amounts of pesticide on POCIS, and the effect of water temperature on the pesticide sampling rates was evaluated. The sampling rates of 48 pesticides at 18, 24, and 30 °C were obtained, and this study confirmed that increasing trend of sampling rates was resulted with increasing water temperature for many pesticides. PMID:27305429

  17. High temperature furnace modeling and performance verifications

    NASA Technical Reports Server (NTRS)

    Smith, James E., Jr.

    1991-01-01

    A two dimensional conduction/radiation problem for an alumina crucible in a zirconia heater/muffle tube enclosing a liquid iron sample was solved numerically. Variations in the crucible wall thickness were numerically examined. The results showed that the temperature profiles within the liquid iron sample were significantly affected by the crucible wall thicknesses. New zirconia heating elements are under development that will permit continued experimental investigations of the zirconia furnace. These elements have been designed to work with the existing furnace and have been shown to have longer lifetimes than commercially available zirconia heating elements. The first element has been constructed and tested successfully.

  18. Automated sample plan selection for OPC modeling

    NASA Astrophysics Data System (ADS)

    Casati, Nathalie; Gabrani, Maria; Viswanathan, Ramya; Bayraktar, Zikri; Jaiswal, Om; DeMaris, David; Abdo, Amr Y.; Oberschmidt, James; Krause, Andreas

    2014-03-01

    It is desired to reduce the time required to produce metrology data for calibration of Optical Proximity Correction (OPC) models and also maintain or improve the quality of the data collected with regard to how well that data represents the types of patterns that occur in real circuit designs. Previous work based on clustering in geometry and/or image parameter space has shown some benefit over strictly manual or intuitive selection, but leads to arbitrary pattern exclusion or selection which may not be the best representation of the product. Forming the pattern selection as an optimization problem, which co-optimizes a number of objective functions reflecting modelers' insight and expertise, has shown to produce models with equivalent quality to the traditional plan of record (POR) set but in a less time.

  19. Sample Size Determination for Rasch Model Tests

    ERIC Educational Resources Information Center

    Draxler, Clemens

    2010-01-01

    This paper is concerned with supplementing statistical tests for the Rasch model so that additionally to the probability of the error of the first kind (Type I probability) the probability of the error of the second kind (Type II probability) can be controlled at a predetermined level by basing the test on the appropriate number of observations.…

  20. Determination of Thermal-Diffusivity Dependence on Temperature of Transparent Samples by Thermal Wave Method

    NASA Astrophysics Data System (ADS)

    Kaźmierczak-Bałata, Anna; Bodzenta, Jerzy; Trefon-Radziejewska, Dominika

    2010-01-01

    The use of a typical measuring cryostat with a standard temperature controller was proposed for investigation of the temperature dependence of the thermal diffusivity of transparent samples. The basic idea is to use the cryostat heater to control the mean sample temperature and to generate the thermal wave in it, simultaneously. Because of the relatively high thermal inertia of the system, the measurements are carried out at frequencies not exceeding 50 mHz. The periodic temperature disturbance in the sample was detected optically by the use of the mirage effect. The proposed method was used for determination of the thermal diffusivity of yttrium aluminum garnet single crystals in a temperature range from 20 °C to 200 °C.

  1. Modeling complexometric titrations of natural water samples.

    PubMed

    Hudson, Robert J M; Rue, Eden L; Bruland, Kenneth W

    2003-04-15

    Complexometric titrations are the primary source of metal speciation data for aquatic systems, yet their interpretation in waters containing humic and fulvic acids remains problematic. In particular, the accuracy of inferred ambient free metal ion concentrations and parameters quantifying metal complexation by natural ligands has been challenged because of the difficulties inherent in calibrating common analytical methods and in modeling the diverse array of ligands present. This work tests and applies a new method of modeling titration data that combines calibration of analytical sensitivity (S) and estimation of concentrations and stability constants for discrete natural ligand classes ([Li]T and Ki) into a single step using nonlinear regression and a new analytical solution to the one-metal/two-ligand equilibrium problem. When applied to jointly model data from multiple titrations conducted at different analytical windows, it yields accurate estimates of S, [Li]T, Ki, and [Cu2+] plus Monte Carlo-based estimates of the uncertainty in [Cu2+]. Jointly modeling titration data at low-and high-analytical windows leads to an efficient adaptation of the recently proposed "overload" approach to calibrating ACSV/CLE measurements. Application of the method to published data sets yields model results with greater accuracy and precision than originally obtained. The discrete ligand-class model is also re-parametrized, using humic and fulvic acids, L1 class (K1 = 10(13) M(-1)), and strong ligands (L(S)) with K(S) > K1 as "natural components". This approach suggests that Cu complexation in NW Mediterranean Sea water can be well represented as 0.8 +/- 0.3/0.2 mg humic equiv/L, 13 +/- 1 nM L1, and 2.5 +/- 0.1 nM L(S) with [CU]T = 3 nM. In coastal seawater from Narragansett Bay, RI, Cu speciation can be modeled as 0.6 +/- 0.1 mg humic equiv/L and 22 +/- 1 nM L1 or approximately 12 nM L1 and approximately 9 nM L(S), with [CU]T = 13 nM. In both waters, the large excess

  2. The XXL Survey . IV. Mass-temperature relation of the bright cluster sample

    NASA Astrophysics Data System (ADS)

    Lieu, M.; Smith, G. P.; Giles, P. A.; Ziparo, F.; Maughan, B. J.; Démoclès, J.; Pacaud, F.; Pierre, M.; Adami, C.; Bahé, Y. M.; Clerc, N.; Chiappetti, L.; Eckert, D.; Ettori, S.; Lavoie, S.; Le Fevre, J. P.; McCarthy, I. G.; Kilbinger, M.; Ponman, T. J.; Sadibekova, T.; Willis, J. P.

    2016-06-01

    Context. The XXL Survey is the largest survey carried out by XMM-Newton. Covering an area of 50 deg2, the survey contains ~450 galaxy clusters out to a redshift ~2 and to an X-ray flux limit of ~ 5 × 10-15 erg s-1 cm-2. This paper is part of the first release of XXL results focussed on the bright cluster sample. Aims: We investigate the scaling relation between weak-lensing mass and X-ray temperature for the brightest clusters in XXL. The scaling relation discussed in this article is used to estimate the mass of all 100 clusters in XXL-100-GC. Methods: Based on a subsample of 38 objects that lie within the intersection of the northern XXL field and the publicly available CFHTLenS shear catalog, we derive the weak-lensing mass of each system with careful considerations of the systematics. The clusters lie at 0.1 temperature range of T ≃ 1-5 keV. We combine our sample with an additional 58 clusters from the literature, increasing the range to T ≃ 1-10 keV. To date, this is the largest sample of clusters with weak-lensing mass measurements that has been used to study the mass-temperature relation. Results: The mass-temperature relation fit (M ∝ Tb) to the XXL clusters returns a slope and intrinsic scatter σlnM|T≃ 0.53; the scatter is dominated by disturbed clusters. The fit to the combined sample of 96 clusters is in tension with self-similarity, b = 1.67 ± 0.12 and σlnM|T ≃ 0.41. Conclusions: Overall our results demonstrate the feasibility of ground-based weak-lensing scaling relation studies down to cool systems of ~1 keV temperature and highlight that the current data and samples are a limit to our statistical precision. As such we are unable to determine whether the validity of hydrostatic equilibrium is a function of halo mass. An enlarged sample of cool systems, deeper weak-lensing data, and robust modelling of the selection function will help to explore these issues further. Based on observations obtained with XMM-Newton, an ESA

  3. Simple method for highlighting the temperature distribution into a liquid sample heated by microwave power field

    SciTech Connect

    Surducan, V.; Surducan, E.; Dadarlat, D.

    2013-11-13

    Microwave induced heating is widely used in medical treatments, scientific and industrial applications. The temperature field inside a microwave heated sample is often inhomogenous, therefore multiple temperature sensors are required for an accurate result. Nowadays, non-contact (Infra Red thermography or microwave radiometry) or direct contact temperature measurement methods (expensive and sophisticated fiber optic temperature sensors transparent to microwave radiation) are mainly used. IR thermography gives only the surface temperature and can not be used for measuring temperature distributions in cross sections of a sample. In this paper we present a very simple experimental method for temperature distribution highlighting inside a cross section of a liquid sample, heated by a microwave radiation through a coaxial applicator. The method proposed is able to offer qualitative information about the heating distribution, using a temperature sensitive liquid crystal sheet. Inhomogeneities as smaller as 1°-2°C produced by the symmetry irregularities of the microwave applicator can be easily detected by visual inspection or by computer assisted color to temperature conversion. Therefore, the microwave applicator is tuned and verified with described method until the temperature inhomogeneities are solved.

  4. Apparatus Measures Thermal Conductance Through a Thin Sample from Cryogenic to Room Temperature

    NASA Technical Reports Server (NTRS)

    Tuttle, James G.

    2009-01-01

    An apparatus allows the measurement of the thermal conductance across a thin sample clamped between metal plates, including thermal boundary resistances. It allows in-situ variation of the clamping force from zero to 30 lb (133.4 N), and variation of the sample temperature between 40 and 300 K. It has a special design feature that minimizes the effect of thermal radiation on this measurement. The apparatus includes a heater plate sandwiched between two identical thin samples. On the side of each sample opposite the heater plate is a cold plate. In order to take data, the heater plate is controlled at a slightly higher temperature than the two cold plates, which are controlled at a single lower temperature. The steady-state controlling power supplied to the hot plate, the area and thickness of samples, and the temperature drop across the samples are then used in a simple calculation of the thermal conductance. The conductance measurements can be taken at arbitrary temperatures down to about 40 K, as the entire setup is cooled by a mechanical cryocooler. The specific geometry combined with the pneumatic clamping force control system and the steady-state temperature control approach make this a unique apparatus.

  5. The ice nucleation temperature determines the primary drying rate of lyophilization for samples frozen on a temperature-controlled shelf.

    PubMed

    Searles, J A; Carpenter, J F; Randolph, T W

    2001-07-01

    The objective of this study was to determine the influence of ice nucleation temperature on the primary drying rate during lyophilization for samples in vials that were frozen on a lyophilizer shelf. Aqueous solutions of 10% (w/v) hydroxyethyl starch were frozen in vials with externally mounted thermocouples and then partially lyophilized to determine the primary drying rate. Low- and high-particulate-containing samples, ice-nucleating additives silver iodide and Pseudomonas syringae, and other methods were used to obtain a wide range of nucleation temperatures. In cases where the supercooling exceeded 5 degrees C, freezing took place in the following three steps: (1) primary nucleation, (2) secondary nucleation encompassing the entire liquid volume, and (3) final solidification. The primary drying rate was dependent on the ice nucleation temperature, which is stochastic in nature but is affected by particulate content and the presence of ice nucleators. Sample cooling rates of 0.05 to 1 degrees C/min had no effect on nucleation temperatures and drying rate. We found that the ice nucleation temperature is the primary determinant of the primary drying rate. However, the nucleation temperature is not under direct control, and its stochastic nature and sensitivity to difficult-to-control parameters result in drying rate heterogeneity. Nucleation temperature heterogeneity may also result in variation in other morphology-related parameters such as surface area and secondary drying rate. Overall, these results document that factors such as particulate content and vial condition, which influence ice nucleation temperature, must be carefully controlled to avoid, for example, lot-to-lot variability during cGMP production. In addition, if these factors are not controlled and/or are inadvertently changed during process development and scaleup, a lyophilization cycle that was successful on the research scale may fail during large-scale production. PMID:11458335

  6. Surface Temperature Assimilation in Land Surface Models

    NASA Technical Reports Server (NTRS)

    Lakshmi, Venkataraman

    1999-01-01

    This paper examines the utilization of surface temperature as a variable to be assimilated in offline land surface hydrological models. Comparisons between the model computed and satellite observed surface temperatures have been carried out. The assimilation of surface temperature is carried out twice a day (corresponding to the AM and PM overpass of the NOAA10) over the Red-Arkansas basin in the Southwestern United States (31 degs 50 sec N - 36 degrees N, 94 degrees 30 seconds W - 104 degrees 3 seconds W) for a period of one year (August 1987 to July 1988). The effect of assimilation is to reduce the difference between the surface soil moisture computed for the precipitation and/or shortwave radiation perturbed case and the unperturbed case compared to no assimilation.

  7. Surface Temperature Assimilation in Land Surface Models

    NASA Technical Reports Server (NTRS)

    Lakshmi, Venkataraman

    1997-01-01

    This paper examines the utilization of surface temperature as a variable to be assimilated in offline land surface hydrological models. Comparisons between the model computed and satellite observed surface temperatures have been carried out. The assimilation of surface temperature is carried out twice a day (corresponding to the AM and PM overpass of the NOAA10) over the Red- Arkansas basin in the Southwestern United States (31 deg 50 min N - 36 deg N, 94 deg 30 min W - 104 deg 30 min W) for a period of one year (August 1987 to July 1988). The effect of assimilation is to reduce the difference between the surface soil moisture computed for the precipitation and/or shortwave radiation perturbed case and the unperturbed case compared to no assimilation.

  8. Automated sample exchange and tracking system for neutron research at cryogenic temperatures.

    PubMed

    Rix, J E; Weber, J K R; Santodonato, L J; Hill, B; Walker, L M; McPherson, R; Wenzel, J; Hammons, S E; Hodges, J; Rennich, M; Volin, K J

    2007-01-01

    An automated system for sample exchange and tracking in a cryogenic environment and under remote computer control was developed. Up to 24 sample "cans" per cycle can be inserted and retrieved in a programed sequence. A video camera acquires a unique identification marked on the sample can to provide a record of the sequence. All operations are coordinated via a LABVIEW program that can be operated locally or over a network. The samples are contained in vanadium cans of 6-10 mm in diameter and equipped with a hermetically sealed lid that interfaces with the sample handler. The system uses a closed-cycle refrigerator (CCR) for cooling. The sample was delivered to a precooling location that was at a temperature of approximately 25 K, after several minutes, it was moved onto a "landing pad" at approximately 10 K that locates the sample in the probe beam. After the sample was released onto the landing pad, the sample handler was retracted. Reading the sample identification and the exchange operation takes approximately 2 min. The time to cool the sample from ambient temperature to approximately 10 K was approximately 7 min including precooling time. The cooling time increases to approximately 12 min if precooling is not used. Small differences in cooling rate were observed between sample materials and for different sample can sizes. Filling the sample well and the sample can with low pressure helium is essential to provide heat transfer and to achieve useful cooling rates. A resistive heating coil can be used to offset the refrigeration so that temperatures up to approximately 350 K can be accessed and controlled using a proportional-integral-derivative control loop. The time for the landing pad to cool to approximately 10 K after it has been heated to approximately 240 K was approximately 20 min. PMID:17503933

  9. Evaluation of the Validity of Crystallization Temperature Measurements Using Thermography with Different Sample Configurations

    NASA Astrophysics Data System (ADS)

    Yuko Aono,; Junpei Sakurai,; Akira Shimokohbe,; Seiichi Hata,

    2010-07-01

    We describe further progress of a previously reported novel crystallization temperature (Tx) measurement method applicable for small sample sizes. The method uses thermography and detects Tx as a change in emissivity of thin film amorphous alloy samples. We applied this method to various sample configurations of Pd-Cu-Si thin film metallic glass (TFMG). The validity of the detected Tx was determined by electrical resistivity monitoring and differential scanning calorimetry (DSC). Crystallization temperature can be detected in all sample configurations; however, it was found that the magnitude of the detected change of emissivity at Tx depended on the sample configuration. This emissivity change was clear in the absence of a higher emissivity material. The results suggest that this method can achieve high-throughput characterization of Tx for integrated small samples such as in a thin film library.

  10. Metamorphism during temperature gradient with undersaturated advective airflow in a snow sample

    NASA Astrophysics Data System (ADS)

    Ebner, Pirmin Philipp; Schneebeli, Martin; Steinfeld, Aldo

    2016-04-01

    Snow at or close to the surface commonly undergoes temperature gradient metamorphism under advective flow, which alters its microstructure and physical properties. Time-lapse X-ray microtomography is applied to investigate the structural dynamics of temperature gradient snow metamorphism exposed to an advective airflow in controlled laboratory conditions. Cold saturated air at the inlet was blown into the snow samples and warmed up while flowing across the sample with a temperature gradient of around 50 K m-1. Changes of the porous ice structure were observed at mid-height of the snow sample. Sublimation occurred due to the slight undersaturation of the incoming air into the warmer ice matrix. Diffusion of water vapor opposite to the direction of the temperature gradient counteracted the mass transport of advection. Therefore, the total net ice change was negligible leading to a constant porosity profile. However, the strong recrystallization of water molecules in snow may impact its isotopic or chemical content.

  11. Two-temperature models for nitrogen dissociation

    NASA Astrophysics Data System (ADS)

    da Silva, M. Lino; Guerra, V.; Loureiro, J.

    2007-12-01

    Accurate sets of nitrogen state-resolved dissociation rates have been reduced to two-temperature (translational T and vibrational Tv) dissociation rates. The analysis of such two-temperature dissociation rates shows evidence of two different dissociation behaviors. For Tv < 0.3 T dissociation proceeds predominantly from the lower-lying vibrational levels, whereas for Tv > 0.3 T dissociation proceeds predominantly form the near-dissociative vibrational levels, with an abrupt change of behavior at Tv = 0.3 T. These two-temperature sets have then been utilized as a benchmark for the comparison against popular multitemperature dissociation models (Park, Hansen, Marrone-Treanor, Hammerling, Losev-Shatalov, Gordiets, Kuznetsov, and Macheret-Fridman). This has allowed verifying the accuracy of each theoretical model, and additionally proposing adequate values for any semi-empirical parameters present in the different theories. The Macheret-Fridman model, who acknowledges the existence of the two aforementioned dissociation regimes, has been found to provide significantly more accurate results than the other models. Although these different theoretical approaches have been tested and validated solely for nitrogen dissociation processes, it is reasonable to expect that the general conclusions of this work, regarding the adequacy of the different dissociation models, could be extended to the description of arbitrary diatomic dissociation processes.

  12. Flight summaries and temperature climatology at airliner cruise altitudes from GASP (Global Atmospheric Sampling Program) data

    NASA Technical Reports Server (NTRS)

    Nastrom, G. D.; Jasperson, W. H.

    1983-01-01

    Temperature data obtained by the Global Atmospheric Sampling Program (GASP) during the period March 1975 to July 1979 are compiled to form flight summaries of static air temperature and a geographic temperature climatology. The flight summaries include the height and location of the coldest observed temperature and the mean flight level, temperature and the standard deviation of temperature for each flight as well as for flight segments. These summaries are ordered by route and month. The temperature climatology was computed for all statistically independent temperture data for each flight. The grid used consists of 5 deg latitude, 30 deg longitude and 2000 feet vertical resolution from FL270 to FL430 for each month of the year. The number of statistically independent observations, their mean, standard deviation and the empirical 98, 50, 16, 2 and .3 probability percentiles are presented.

  13. Measurement of Crystallization Temperature Using Thermography for Thin Film Amorphous Alloy Samples

    NASA Astrophysics Data System (ADS)

    Hata, Seiichi; Aono, Yuko; Sakurai, Junpei; Shimokohbe, Akira

    2009-03-01

    This report describes a new non-contact measurement method for the crystallization temperature (Tx) of a thin film amorphous alloy. The thermal emissivity of the amorphous alloy sample is predicted to be modified when it crystallizes. It was attempted to relate this modification to changes in the apparent temperature by thermography. Thin film amorphous alloys of Pt67Si33 and Pt73Si27 were sputtered onto an Al2O3 substrate and then heated at 20 K/min in vacuum, and the film temperature was monitored by thermography. The Tx indicated by the proposed method coincided with the temperature measured by conventional differential scanning calorimeter within 8 K.

  14. The XXL Survey. III. Luminosity-temperature relation of the bright cluster sample

    NASA Astrophysics Data System (ADS)

    Giles, P. A.; Maughan, B. J.; Pacaud, F.; Lieu, M.; Clerc, N.; Pierre, M.; Adami, C.; Chiappetti, L.; Démoclés, J.; Ettori, S.; Le Févre, J. P.; Ponman, T.; Sadibekova, T.; Smith, G. P.; Willis, J. P.; Ziparo, F.

    2016-06-01

    Context. The XXL Survey is the largest homogeneous survey carried out with XMM-Newton. Covering an area of 50 deg2, the survey contains several hundred galaxy clusters out to a redshift of ~2 above an X-ray flux limit of ~5 × 10-15 erg cm-2 s-1. This paper belongs to the first series of XXL papers focusing on the bright cluster sample. Aims: We investigate the luminosity-temperature (LT) relation for the brightest clusters detected in the XXL Survey, taking fully into account the selection biases. We investigate the form of the LT relation, placing constraints on its evolution. Methods: We have classified the 100 brightest clusters in the XXL Survey based on their measured X-ray flux. These 100 clusters have been analysed to determine their luminosity and temperature to evaluate the LT relation. We used three methods to fit the form of the LT relation, with two of these methods providing a prescription to fully take into account the selection effects of the survey. We measure the evolution of the LT relation internally using the broad redshift range of the sample. Results: Taking fully into account selection effects, we find a slope of the bolometric LT relation of BLT = 3.08 ± 0.15, steeper than the self-similar expectation (BLT = 2). Our best-fit result for the evolution factor is E(z)1.64 ± 0.77, fully consistent with "strong self-similar" evolution where clusters scale self-similarly with both mass and redshift. However, this result is marginally stronger than "weak self-similar" evolution, where clusters scale with redshift alone. We investigate the sensitivity of our results to the assumptions made in our fitting model, finding that using an external LT relation as a low-z baseline can have a profound effect on the measured evolution. However, more clusters are needed in order to break the degeneracy between the choice of likelihood model and mass-temperature relation on the derived evolution. Based on observations obtained with XMM-Newton, an ESA science

  15. Preferential sampling and Bayesian geostatistics: Statistical modeling and examples.

    PubMed

    Cecconi, Lorenzo; Grisotto, Laura; Catelan, Dolores; Lagazio, Corrado; Berrocal, Veronica; Biggeri, Annibale

    2016-08-01

    Preferential sampling refers to any situation in which the spatial process and the sampling locations are not stochastically independent. In this paper, we present two examples of geostatistical analysis in which the usual assumption of stochastic independence between the point process and the measurement process is violated. To account for preferential sampling, we specify a flexible and general Bayesian geostatistical model that includes a shared spatial random component. We apply the proposed model to two different case studies that allow us to highlight three different modeling and inferential aspects of geostatistical modeling under preferential sampling: (1) continuous or finite spatial sampling frame; (2) underlying causal model and relevant covariates; and (3) inferential goals related to mean prediction surface or prediction uncertainty. PMID:27566774

  16. Modeling quantum fluid dynamics at nonzero temperatures

    PubMed Central

    Berloff, Natalia G.; Brachet, Marc; Proukakis, Nick P.

    2014-01-01

    The detailed understanding of the intricate dynamics of quantum fluids, in particular in the rapidly growing subfield of quantum turbulence which elucidates the evolution of a vortex tangle in a superfluid, requires an in-depth understanding of the role of finite temperature in such systems. The Landau two-fluid model is the most successful hydrodynamical theory of superfluid helium, but by the nature of the scale separations it cannot give an adequate description of the processes involving vortex dynamics and interactions. In our contribution we introduce a framework based on a nonlinear classical-field equation that is mathematically identical to the Landau model and provides a mechanism for severing and coalescence of vortex lines, so that the questions related to the behavior of quantized vortices can be addressed self-consistently. The correct equation of state as well as nonlocality of interactions that leads to the existence of the roton minimum can also be introduced in such description. We review and apply the ideas developed for finite-temperature description of weakly interacting Bose gases as possible extensions and numerical refinements of the proposed method. We apply this method to elucidate the behavior of the vortices during expansion and contraction following the change in applied pressure. We show that at low temperatures, during the contraction of the vortex core as the negative pressure grows back to positive values, the vortex line density grows through a mechanism of vortex multiplication. This mechanism is suppressed at high temperatures. PMID:24704874

  17. An environmental sampling model for combining judgment and randomly placed samples

    SciTech Connect

    Sego, Landon H.; Anderson, Kevin K.; Matzke, Brett D.; Sieber, Karl; Shulman, Stanley; Bennett, James; Gillen, M.; Wilson, John E.; Pulsipher, Brent A.

    2007-08-23

    In the event of the release of a lethal agent (such as anthrax) inside a building, law enforcement and public health responders take samples to identify and characterize the contamination. Sample locations may be rapidly chosen based on available incident details and professional judgment. To achieve greater confidence of whether or not a room or zone was contaminated, or to certify that detectable contamination is not present after decontamination, we consider a Bayesian model for combining the information gained from both judgment and randomly placed samples. We investigate the sensitivity of the model to the parameter inputs and make recommendations for its practical use.

  18. Thermal Response Modeling System for a Mars Sample Return Vehicle

    NASA Technical Reports Server (NTRS)

    Chen, Y.-K.; Milos, F. S.

    2002-01-01

    A multi-dimensional, coupled thermal response modeling system for analysis of hypersonic entry vehicles is presented. The system consists of a high fidelity Navier-Stokes equation solver (GIANTS), a two-dimensional implicit thermal response, pyrolysis and ablation program (TITAN), and a commercial finite element thermal and mechanical analysis code (MARC). The simulations performed by this integrated system include hypersonic flowfield, fluid and solid interaction, ablation, shape change, pyrolysis gas generation and flow, and thermal response of heatshield and structure. The thermal response of the heatshield is simulated using TITAN, and that of the underlying structural is simulated using MARC. The ablating heatshield is treated as an outer boundary condition of the structure, and continuity conditions of temperature and heat flux are imposed at the interface between TITAN and MARC. Aerothermal environments with fluid and solid interaction are predicted by coupling TITAN and GIANTS through surface energy balance equations. With this integrated system, the aerothermal environments for an entry vehicle and the thermal response of the entire vehicle can be obtained simultaneously. Representative computations for a flat-faced arc-jet test model and a proposed Mars sample return capsule are presented and discussed.

  19. Thermal Response Modeling System for a Mars Sample Return Vehicle

    NASA Technical Reports Server (NTRS)

    Chen, Y.-K.; Miles, Frank S.; Arnold, Jim (Technical Monitor)

    2001-01-01

    A multi-dimensional, coupled thermal response modeling system for analysis of hypersonic entry vehicles is presented. The system consists of a high fidelity Navier-Stokes equation solver (GIANTS), a two-dimensional implicit thermal response, pyrolysis and ablation program (TITAN), and a commercial finite-element thermal and mechanical analysis code (MARC). The simulations performed by this integrated system include hypersonic flowfield, fluid and solid interaction, ablation, shape change, pyrolysis gas eneration and flow, and thermal response of heatshield and structure. The thermal response of the heatshield is simulated using TITAN, and that of the underlying structural is simulated using MARC. The ablating heatshield is treated as an outer boundary condition of the structure, and continuity conditions of temperature and heat flux are imposed at the interface between TITAN and MARC. Aerothermal environments with fluid and solid interaction are predicted by coupling TITAN and GIANTS through surface energy balance equations. With this integrated system, the aerothermal environments for an entry vehicle and the thermal response of the entire vehicle can be obtained simultaneously. Representative computations for a flat-faced arc-jet test model and a proposed Mars sample return capsule are presented and discussed.

  20. Modeling forces in high-temperature superconductors

    SciTech Connect

    Turner, L. R.; Foster, M. W.

    1997-11-18

    We have developed a simple model that uses computed shielding currents to determine the forces acting on a high-temperature superconductor (HTS). The model has been applied to measurements of the force between HTS and permanent magnets (PM). Results show the expected hysteretic variation of force as the HTS moves first toward and then away from a permanent magnet, including the reversal of the sign of the force. Optimization of the shielding currents is carried out through a simulated annealing algorithm in a C++ program that repeatedly calls a commercial electromagnetic software code. Agreement with measured forces is encouraging.

  1. Method and apparatus for transport, introduction, atomization and excitation of emission spectrum for quantitative analysis of high temperature gas sample streams containing vapor and particulates without degradation of sample stream temperature

    SciTech Connect

    Eckels, D.E.; Hass, W.J.

    1989-05-30

    A sample transport, sample introduction, and flame excitation system is described for spectrometric analysis of high temperature gas streams which eliminates degradation of the sample stream by condensation losses. 4 figs.

  2. Comparison of Single-Point and Continuous Sampling Methods for Estimating Residential Indoor Temperature and Humidity.

    PubMed

    Johnston, James D; Magnusson, Brianna M; Eggett, Dennis; Collingwood, Scott C; Bernhardt, Scott A

    2015-01-01

    Residential temperature and humidity are associated with multiple health effects. Studies commonly use single-point measures to estimate indoor temperature and humidity exposures, but there is little evidence to support this sampling strategy. This study evaluated the relationship between single-point and continuous monitoring of air temperature, apparent temperature, relative humidity, and absolute humidity over four exposure intervals (5-min, 30-min, 24-hr, and 12-days) in 9 northern Utah homes, from March-June 2012. Three homes were sampled twice, for a total of 12 observation periods. Continuous data-logged sampling was conducted in homes for 2-3 wks, and simultaneous single-point measures (n = 114) were collected using handheld thermo-hygrometers. Time-centered single-point measures were moderately correlated with short-term (30-min) data logger mean air temperature (r = 0.76, β = 0.74), apparent temperature (r = 0.79, β = 0.79), relative humidity (r = 0.70, β = 0.63), and absolute humidity (r = 0.80, β = 0.80). Data logger 12-day means were also moderately correlated with single-point air temperature (r = 0.64, β = 0.43) and apparent temperature (r = 0.64, β = 0.44), but were weakly correlated with single-point relative humidity (r = 0.53, β = 0.35) and absolute humidity (r = 0.52, β = 0.39). Of the single-point RH measures, 59 (51.8%) deviated more than ±5%, 21 (18.4%) deviated more than ±10%, and 6 (5.3%) deviated more than ±15% from data logger 12-day means. Where continuous indoor monitoring is not feasible, single-point sampling strategies should include multiple measures collected at prescribed time points based on local conditions. PMID:26030088

  3. The use of ESR technique for assessment of heating temperatures of archaeological lentil samples

    NASA Astrophysics Data System (ADS)

    Aydaş, Canan; Engin, Birol; Dönmez, Emel Oybak; Belli, Oktay

    2010-01-01

    Heat-induced paramagnetic centers in modern and archaeological lentils ( Lens culinaris, Medik.) were studied by X-band (9.3 GHz) electron spin resonance (ESR) technique. The modern red lentil samples were heated in an electrical furnace at increasing temperatures in the range 70-500 °C. The ESR spectral parameters (the intensity, g-value and peak-to-peak line width) of the heat-induced organic radicals were investigated for modern red lentil ( Lens culinaris, Medik.) samples. The obtained ESR spectra indicate that the relative number of heat-induced paramagnetic species and peak-to-peak line widths depends on the temperature and heating time of the modern lentil. The g-values also depend on the heating temperature but not heating time. Heated modern red lentils produced a range of organic radicals with g-values from g = 2.0062 to 2.0035. ESR signals of carbonised archaeological lentil samples from two archaeological deposits of the Van province in Turkey were studied and g-values, peak-to-peak line widths, intensities and elemental compositions were compared with those obtained for modern samples in order to assess at which temperature these archaeological lentils were heated in prehistoric sites. The maximum temperatures of the previous heating of carbonised UA5 and Y11 lentil seeds are as follows about 500 °C and above 500 °C, respectively.

  4. The use of variable temperature and magic-angle sample spinning in studies of fulvic acids

    USGS Publications Warehouse

    Earl, W.L.; Wershaw, R. L.; Thorn, K.A.

    1987-01-01

    Intensity distortions and poor signal to noise in the cross-polarization magic-angle sample spinning NMR of fulvic acids were investigated and attributed to molecular mobility in these ostensibly "solid" materials. We have shown that inefficiencies in cross polarization can be overcome by lowering the sample temperature to about -60??C. These difficulties can be generalized to many other synthetic and natural products. The use of variable temperature and cross-polarization intensity as a function of contact time can yield valuable qualitative information which can aid in the characterization of many materials. ?? 1987.

  5. Temperature-controlled neutron reflectometry sample cell suitable for study of photoactive thin films

    SciTech Connect

    Yager, Kevin G.; Tanchak, Oleh M.; Barrett, Christopher J.; Watson, Mike J.; Fritzsche, Helmut

    2006-04-15

    We describe a novel cell design intended for the study of photoactive materials using neutron reflectometry. The cell can maintain sample temperature and control of ambient atmospheric environment. Critically, the cell is built with an optical port, enabling light irradiation or light probing of the sample, simultaneous with neutron reflectivity measurements. The ability to measure neutron reflectivity with simultaneous temperature ramping and/or light illumination presents unique opportunities for measuring photoactive materials. To validate the cell design, we present preliminary results measuring the photoexpansion of thin films of azobenzene polymer.

  6. Geothermal fluid equilibrium modeling: a comparison of wellhead fluid samples to deep samples in the Reykjanes system Iceland

    NASA Astrophysics Data System (ADS)

    Seward, R. J.; Reed, M. H.; Fridriksson, T.

    2013-12-01

    Single phase geothermal fluids sampled at depth (Hardardottir et al. 2007) from the Reykjanes geothermal system in Iceland show large differences in dissolved copper, zinc, and iron concentrations when compared with fluid sampled from the same well at the surface. Equilibrium modeling of the samples taken at depth indicate that the fluid was supersaturated in sulfide minerals even at moderately acidic pH values, suggesting that the deep samples, as collected, are out of equilibrium. One possibility for this discrepancy is that the down-well mechanical sampler trapped suspended particles of sulfide minerals that were treated as part of the dissolved constituents of the fluid when it was analyzed, thus inflating the concentrations of Cu, Zn and Fe. In addition to possible entrained solids, techniques used to take in-situ fluid samples at depth in these wells do not provide a complete picture of dissolved species within the fluid because gases are lost when samples are brought to the surface. This precludes meaningful pH measurements and therefore requires chemical modeling of surface samples to understand the state of fluids at depth. In this study geothermal fluids are modeled from surface sample analyses and compared with results from models of fluids collected at depth in the same geothermal wells by calculating a full chemical speciation of geothermal fluids as they boil with decreasing pressure and temperature using programs SOLVEQ-xpt and CHIM-xpt. One of the wells examined for this study was well RN-12. In-situ down-well samples were collected at 1500m, within the single phase region as indicated by pre-sampling pressure and temperature logging in the well which showed that boiling starts at 1300m, and 295 degrees C. Fluid and gas samples which were collected at the well head are recomputed as a single phase fluid to be compared with the down-well sampler. These surface fluids reached a maximum temperature of 300 to 320 degrees C, determined by computing the

  7. Effects of different temperature treatments on biological ice nuclei in snow samples

    NASA Astrophysics Data System (ADS)

    Hara, Kazutaka; Maki, Teruya; Kakikawa, Makiko; Kobayashi, Fumihisa; Matsuki, Atsushi

    2016-09-01

    The heat tolerance of biological ice nucleation activity (INA) depends on their types. Different temperature treatments may cause varying degrees of inactivation on biological ice nuclei (IN) in precipitation samples. In this study, we measured IN concentration and bacterial INA in snow samples using a drop freezing assay, and compared the results for unheated snow and snow treated at 40 °C and 90 °C. At a measured temperature of -7 °C, the concentration of IN in untreated snow was 100-570 L-1, whereas the concentration in snow treated at 40 °C and 90 °C was 31-270 L-1 and 2.5-14 L-1, respectively. In the present study, heat sensitive IN inactivated by heating at 40 °C were predominant, and ranged 23-78% of IN at -7 °C compared with untreated samples. Ice nucleation active Pseudomonas strains were also isolated from the snow samples, and heating at 40 °C and 90 °C inactivated these microorganisms. Consequently, different temperature treatments induced varying degrees of inactivation on IN in snow samples. Differences in the concentration of IN across a range of treatment temperatures might reflect the abundance of different heat sensitive biological IN components.

  8. Estimation of sampling error uncertainties in observed surface air temperature change in China

    NASA Astrophysics Data System (ADS)

    Hua, Wei; Shen, Samuel S. P.; Weithmann, Alexander; Wang, Huijun

    2016-06-01

    This study examines the sampling error uncertainties in the monthly surface air temperature (SAT) change in China over recent decades, focusing on the uncertainties of gridded data, national averages, and linear trends. Results indicate that large sampling error variances appear at the station-sparse area of northern and western China with the maximum value exceeding 2.0 K2 while small sampling error variances are found at the station-dense area of southern and eastern China with most grid values being less than 0.05 K2. In general, the negative temperature existed in each month prior to the 1980s, and a warming in temperature began thereafter, which accelerated in the early and mid-1990s. The increasing trend in the SAT series was observed for each month of the year with the largest temperature increase and highest uncertainty of 0.51 ± 0.29 K (10 year)-1 occurring in February and the weakest trend and smallest uncertainty of 0.13 ± 0.07 K (10 year)-1 in August. The sampling error uncertainties in the national average annual mean SAT series are not sufficiently large to alter the conclusion of the persistent warming in China. In addition, the sampling error uncertainties in the SAT series show a clear variation compared with other uncertainty estimation methods, which is a plausible reason for the inconsistent variations between our estimate and other studies during this period.

  9. Temperature influences in receiver clock modelling

    NASA Astrophysics Data System (ADS)

    Wang, Kan; Meindl, Michael; Rothacher, Markus; Schoenemann, Erik; Enderle, Werner

    2016-04-01

    In Precise Point Positioning (PPP), hardware delays at the receiver site (receiver, cables, antenna, …) are always difficult to be separated from the estimated receiver clock parameters. As a result, they are partially or fully contained in the estimated "apparent" clocks and will influence the deterministic and stochastic modelling of the receiver clock behaviour. In this contribution, using three years of data, the receiver clock corrections of a set of high-precision Hydrogen Masers (H-Masers) connected to stations of the ESA/ESOC network and the International GNSS Service (IGS) are firstly characterized concerning clock offsets, drifts, modified Allan deviations and stochastic parameters. In a second step, the apparent behaviour of the clocks is modelled with the help of a low-order polynomial and a known temperature coefficient (Weinbach, 2013). The correlations between the temperature and the hardware delays generated by different types of antennae are then analysed looking at daily, 3-day and weekly time intervals. The outcome of these analyses is crucial, if we intend to model the receiver clocks in the ground station network to improve the estimation of station-related parameters like coordinates, troposphere zenith delays and ambiguities. References: Weinbach, U. (2013) Feasibility and impact of receiver clock modeling in precise GPS data analysis. Dissertation, Leibniz Universität Hannover, Germany.

  10. Electric transport measurements on bulk, polycrystalline MgB2 samples prepared at various reaction temperatures

    NASA Astrophysics Data System (ADS)

    Wiederhold, A.; Koblischka, M. R.; Inoue, K.; Muralidhar, M.; Murakami, M.; Hartmann, U.

    2016-03-01

    A series of disk-shaped, bulk MgB2 superconductors (sample diameter up to 4 cm) was prepared in order to improve the performance for superconducting super-magnets. Several samples were fabricated using a solid state reaction in pure Ar atmosphere from 750 to 950oC in order to determine the optimum processing parameters to obtain the highest critical current density as well as large trapped field values. Additional samples were prepared with added silver (up to 10 wt.-%) to the Mg and B powder. Magneto-resistance data and I/V-characteristics were recorded using an Oxford Instruments Teslatron system. From Arrhenius plots, we determine the TAFF pinning potential, U 0. The I/V-characteristics yield detailed information on the current flow through the polycrystalline samples. The current flow is influenced by the presence of pores in the samples. Our analysis of the achieved critical currents together with a thorough microstructure investigation reveals that the samples prepared at temperatures between 775°C and 805°C exhibit the smallest grains and the best connectivity between them, while the samples fabricated at higher reaction temperatures show a reduced connectivity and lower pinning potential. Doping the samples with silver leads to a considerable increase of the pinning potential and hence, the critical current densities.

  11. Stratospheric Temperature Changes: Observations and Model Simulations

    NASA Technical Reports Server (NTRS)

    Ramaswamy, V.; Chanin, M.-L.; Angell, J.; Barnett, J.; Gaffen, D.; Gelman, M.; Keckhut, P.; Koshelkov, Y.; Labitzke, K.; Lin, J.-J. R.

    1999-01-01

    This paper reviews observations of stratospheric temperatures that have been made over a period of several decades. Those observed temperatures have been used to assess variations and trends in stratospheric temperatures. A wide range of observation datasets have been used, comprising measurements by radiosonde (1940s to the present), satellite (1979 - present), lidar (1979 - present) and rocketsonde (periods varying with location, but most terminating by about the mid-1990s). In addition, trends have also been assessed from meteorological analyses, based on radiosonde and/or satellite data, and products based on assimilating observations into a general circulation model. Radiosonde and satellite data indicate a cooling trend of the annual-mean lower stratosphere since about 1980. Over the period 1979-1994, the trend is 0.6K/decade. For the period prior to 1980, the radiosonde data exhibit a substantially weaker long-term cooling trend. In the northern hemisphere, the cooling trend is about 0.75K/decade in the lower stratosphere, with a reduction in the cooling in mid-stratosphere (near 35 km), and increased cooling in the upper stratosphere (approximately 2 K per decade at 50 km). Model simulations indicate that the depletion of lower stratospheric ozone is the dominant factor in the observed lower stratospheric cooling. In the middle and upper stratosphere both the well-mixed greenhouse gases (such as CO) and ozone changes contribute in an important manner to the cooling.

  12. TEMPERATURE HISTORY AND DYNAMICAL EVOLUTION OF (101955) 1999 RQ 36: A POTENTIAL TARGET FOR SAMPLE RETURN FROM A PRIMITIVE ASTEROID

    SciTech Connect

    Delbo, Marco; Michel, Patrick

    2011-02-20

    It has been recently shown that near-Earth objects (NEOs) have a temperature history-due to the radiative heating by the Sun-non-trivially correlated to their present orbits. This is because the perihelion distance of NEOs varies as a consequence of dynamical mechanisms, such as resonances and close encounters with planets. Thus, it is worth investigating the temperature history of NEOs that are potential targets of space missions devoted to return samples of prebiotic organic compounds. Some of these compounds, expected to be found on NEOs of primitive composition, break up at moderate temperatures, e.g., 300-670 K. Using a model of the orbital evolution of NEOs and thermal models, we studied the temperature history of (101955) 1999 RQ{sub 36} (the primary target of the mission OSIRIS-REx, proposed in the program New Frontiers of NASA). Assuming that the same material always lies on the surface (i.e., there is no regolith turnover), our results suggest that the temperatures reached during its past evolution affected the stability of some organic compounds at the surface (e.g., there is 50% probability that the surface of 1999 RQ{sub 36} was heated at temperatures {>=}500 K). However, the temperature drops rapidly with depth: the regolith at a depth of 3-5 cm, which is not considered difficult to reach with the current designs of sampling devices, has experienced temperatures about 100 K below those at the surface. This is sufficient to protect some subsurface organics from thermal breakup.

  13. Modelling nanofluidic field amplified sample stacking with inhomogeneous surface charge

    NASA Astrophysics Data System (ADS)

    McCallum, Christopher; Pennathur, Sumita

    2015-11-01

    Nanofluidic technology has exceptional applications as a platform for biological sample preconcentration, which will allow for an effective electronic detection method of low concentration analytes. One such preconcentration method is field amplified sample stacking, a capillary electrophoresis technique that utilizes large concentration differences to generate high electric field gradients, causing the sample of interest to form a narrow, concentrated band. Field amplified sample stacking has been shown to work well at the microscale, with models and experiments confirming expected behavior. However, nanofluidics allows for further concentration enhancement due to focusing of the sample ions toward the channel center by the electric double layer. We have developed a two-dimensional model that can be used for both micro- and nanofluidics, fully accounting for the electric double layer. This model has been used to investigate even more complex physics such as the role of inhomogeneous surface charge.

  14. Estimating peak and solidification temperatures for anatectic pelitic migmatites using phase diagrams: sampling heterogeneous migmatites and confronting melt loss

    NASA Astrophysics Data System (ADS)

    Hamilton, Brett M.; Pattison, David R. M.

    2016-04-01

    Calculating a pressure-temperature phase diagram relevant to an anatectic pelitic migmatite sampled in outcrop is challenging because it is unclear what constitutes a meaningful bulk composition. Melt loss during metamorphism may have changed the bulk composition. The heterogeneous nature of migmatites, with light and dark coloured domains (leucosome and melanosome), means a choice must be made regarding how a migmatitic outcrop should be sampled. To address these issues, migmatites were simulated using thermodynamic modelling techniques for different melting and crystallization scenarios and bulk compositions. Using phase diagrams calculated for varying proportions of simulated melanosome and leucosome, temperatures of interest were estimated and compared with known values. Our modelling suggests: (1) It is generally possible to constrain the peak temperature using phase diagrams calculated with the composition of the melanosome; the more leucosome that is incorporated, the more innaccurate the estimate. For phase diagrams calculated using a combination of leucosome and melanosome material, peak temperature estimates differ from actual peak conditions by ‑25 to +50°C. In certain of these cases, such as those involving high proportions of leucosome to melanosome, or in which solid K-feldspar was absent at peak conditions, but is now present in the rock due to later crystallization from melt, it is not possible to estimate peak temperature. (2) The solidification temperature, whether due to crystallization of the last melt or physical loss of the melt during crystallization, will fall between the peak temperature and the water-saturated solidus (~660°C) if the melt and solids chemically interacted during cooling. This temperature can be accurately constrained from the phase diagram. If the melt crystallized in chemical isolation from the melanosome, the solidification temperature is the water-saturated solidus (625-645°C); however, physical melt loss during

  15. Slice sampling technique in Bayesian extreme of gold price modelling

    NASA Astrophysics Data System (ADS)

    Rostami, Mohammad; Adam, Mohd Bakri; Ibrahim, Noor Akma; Yahya, Mohamed Hisham

    2013-09-01

    In this paper, a simulation study of Bayesian extreme values by using Markov Chain Monte Carlo via slice sampling algorithm is implemented. We compared the accuracy of slice sampling with other methods for a Gumbel model. This study revealed that slice sampling algorithm offers more accurate and closer estimates with less RMSE than other methods . Finally we successfully employed this procedure to estimate the parameters of Malaysia extreme gold price from 2000 to 2011.

  16. Long-term storage of salivary cortisol samples at room temperature

    NASA Technical Reports Server (NTRS)

    Chen, Yu-Ming; Cintron, Nitza M.; Whitson, Peggy A.

    1992-01-01

    Collection of saliva samples for the measurement of cortisol during space flights provides a simple technique for studying changes in adrenal function due microgravity. In the present work, several methods for preserving saliva cortisol at room temperature were investigated using radioimmunoassays for determining cortisol in saliva samples collected on a saliva-collection device called Salivettes. It was found that a pretreatment of Salivettes with citric acid resulted in preserving more than 85 percent of the salivary cortisol for as long as six weeks. The results correlated well with those for a sample stored in a freezer on an untreated Salivette.

  17. Performance of Random Effects Model Estimators under Complex Sampling Designs

    ERIC Educational Resources Information Center

    Jia, Yue; Stokes, Lynne; Harris, Ian; Wang, Yan

    2011-01-01

    In this article, we consider estimation of parameters of random effects models from samples collected via complex multistage designs. Incorporation of sampling weights is one way to reduce estimation bias due to unequal probabilities of selection. Several weighting methods have been proposed in the literature for estimating the parameters of…

  18. Graphite sample preparation for AMS in a high pressure and temperature press

    USGS Publications Warehouse

    Rubin, M.; Mysen, B.O.; Polach, H.

    1984-01-01

    A high pressure-high temperature press is used to make target material for accelerator mass spectrometry. Graphite was produced from typical 14C samples including oxalic acid and carbonates. Beam strength of 12C was generally adequate, but random radioactive contamination by 14C made age measurements impractical. ?? 1984.

  19. Graphite sample preparation for AMS in a high pressure and temperature press

    USGS Publications Warehouse

    Rubin, Meyer; Mysen, Bjorn O.; Polach, Henry

    1984-01-01

    A high pressure-temperature press is used to make target material for accelerator mass spectrometry. Graphite was produced from typical **1**4C samples including oxalic acid and carbonates. Beam strength of **1**2C was generally adequate, but random radioactive contamination by **1**4C made age measurements impractical.

  20. Slow and rapid response: The temperature memory of smectite in JFAST's Tohoku earthquake core samples (Japan)

    NASA Astrophysics Data System (ADS)

    Schleicher, Anja M.; Boles, Austin; van der Pluijm, Ben A.

    2014-05-01

    The ability of clay minerals to absorb and retain interlayer water during large slip events can be limited because of locally high frictional heating temperatures. Core samples from JFAST (Japan Trench Fast Drilling Project) Expedition 343 provide a unique opportunity to characterize smectitic clay minerals in fault rocks of an active plate-boundary fault that produced a displacement of ~50 meters during the Tohoku earthquake of 2011. Smectite is abundant in the fault zone identified at 820 mbsf. Chemical compositions analyzed by ICP-OES show a significant amount of Fe, and lesser Mg and K. In order to analyze the swelling capacity of smectite during slow and rapid temperature changes, we heated and cooled samples in steps of 25 °C from 25 to 225 °C at different rates, using a temperature stage and humidity chamber attached to an X-ray diffractometer. Rapid heating is represented by 5 min and slow heating by 5 hours for each sample. Cooling back to ~25 °C was achieved within 15-40 min, depending on the maximum heating temperature. X-ray analyses of randomly-oriented and oriented samples were conducted on air-dried and glycolated samples. Illite and smectite are the most abundant clay mineral types detected. Mineralogic characterization of illite shows 1Md and 2M1 polytypes, with authigenically formed 1Md slightly more abundant in the finer grained material. Clay size fractions 0.05 - 0.5 microns show pure smectite with a characteristic interlayer distance of 1.2 nm that increases to 1.7 nm after ethylene glycolization, indicating up to 3 water layers. Based on slow and rapid heating and cooling experiments of these samples, we observe that (i) both slow and fast heating causes similar reduction of water layers in smectite, (ii) smectite recovers faster to the original hydration state after quick heating than slow heating, and (iii) non-recoverable collapse of all smectite occurs at temperatures > 200 °C, regardless of the heating rate. Based on these results

  1. Calorimeters for Precision Power Dissipation Measurements on Controlled-Temperature Superconducting Radiofrequency Samples

    SciTech Connect

    Xiao, Binping P.; Kelley, Michael J.; Reece, Charles E.; Phillips, H. L.

    2012-12-01

    Two calorimeters, with stainless steel and Cu as the thermal path material for high precision and high power versions, respectively, have been designed and commissioned for the surface impedance characterization (SIC) system at Jefferson Lab to provide low temperature control and measurement for CW power up to 22 W on a 5 cm dia. disk sample which is thermally isolated from the RF portion of the system. A power compensation method has been developed to measure the RF induced power on the sample. Simulation and experimental results show that with these two calorimeters, the whole thermal range of interest for superconducting radiofrequency (SRF) materials has been covered. The power measurement error in the interested power range is within 1.2% and 2.7% for the high precision and high power versions, respectively. Temperature distributions on the sample surface for both versions have been simulated and the accuracy of sample temperature measurements have been analysed. Both versions have the ability to accept bulk superconductors and thin film superconducting samples with a variety of substrate materials such as Al, Al{sub 2}O{sub 3}, Cu, MgO, Nb and Si.

  2. Calorimeters for precision power dissipation measurements on controlled-temperature superconducting radiofrequency samples.

    PubMed

    Xiao, B P; Reece, C E; Phillips, H L; Kelley, M J

    2012-12-01

    Two calorimeters, with stainless steel and Cu as the thermal path material for high precision and high power versions, respectively, have been designed and commissioned for the 7.5 GHz surface impedance characterization system at Jefferson Lab to provide low temperature control and measurement for CW power up to 22 W on a 5 cm diameter disk sample which is thermally isolated from the radiofrequency (RF) portion of the system. A power compensation method has been developed to measure the RF induced power on the sample. Simulation and experimental results show that with these two calorimeters, the whole thermal range of interest for superconducting radiofrequency materials has been covered. The power measurement error in the interested power range is within 1.2% and 2.7% for the high precision and high power versions, respectively. Temperature distributions on the sample surface for both versions have been simulated and the accuracy of sample temperature measurements have been analyzed. Both versions have the ability to accept bulk superconductors and thin film superconducting samples with a variety of substrate materials such as Al, Al(2)O(3), Cu, MgO, Nb, and Si. PMID:23278016

  3. Flexible sample environment for high resolution neutron imaging at high temperatures in controlled atmosphere

    NASA Astrophysics Data System (ADS)

    Makowska, Małgorzata G.; Theil Kuhn, Luise; Cleemann, Lars N.; Lauridsen, Erik M.; Bilheux, Hassina Z.; Molaison, Jamie J.; Santodonato, Louis J.; Tremsin, Anton S.; Grosse, Mirco; Morgano, Manuel; Kabra, Saurabh; Strobl, Markus

    2015-12-01

    High material penetration by neutrons allows for experiments using sophisticated sample environments providing complex conditions. Thus, neutron imaging holds potential for performing in situ nondestructive measurements on large samples or even full technological systems, which are not possible with any other technique. This paper presents a new sample environment for in situ high resolution neutron imaging experiments at temperatures from room temperature up to 1100 °C and/or using controllable flow of reactive atmospheres. The design also offers the possibility to directly combine imaging with diffraction measurements. Design, special features, and specification of the furnace are described. In addition, examples of experiments successfully performed at various neutron facilities with the furnace, as well as examples of possible applications are presented. This covers a broad field of research from fundamental to technological investigations of various types of materials and components.

  4. Flexible sample environment for high resolution neutron imaging at high temperatures in controlled atmosphere

    SciTech Connect

    Makowska, Małgorzata G.; Theil Kuhn, Luise; Cleemann, Lars N.; Lauridsen, Erik M.; Bilheux, Hassina Z.; Molaison, Jamie J.; Santodonato, Louis J.; Tremsin, Anton S.; Grosse, Mirco; Morgano, Manuel; Kabra, Saurabh; Strobl, Markus

    2015-12-15

    High material penetration by neutrons allows for experiments using sophisticated sample environments providing complex conditions. Thus, neutron imaging holds potential for performing in situ nondestructive measurements on large samples or even full technological systems, which are not possible with any other technique. This paper presents a new sample environment for in situ high resolution neutron imaging experiments at temperatures from room temperature up to 1100 °C and/or using controllable flow of reactive atmospheres. The design also offers the possibility to directly combine imaging with diffraction measurements. Design, special features, and specification of the furnace are described. In addition, examples of experiments successfully performed at various neutron facilities with the furnace, as well as examples of possible applications are presented. This covers a broad field of research from fundamental to technological investigations of various types of materials and components.

  5. Flexible sample environment for high resolution neutron imaging at high temperatures in controlled atmosphere

    SciTech Connect

    Makowska, Małgorzata G.; Theil Kuhn, Luise; Cleemann, Lars N.; Lauridsen, Erik M.; Bilheux, Hassina Z.; Molaison, Jamie J.; Santodonato, Louis J.; Tremsin, Anton S.; Grosse, Mirco; Morgano, Manuel; Kabra, Saurabh; Strobl, Markus

    2015-12-17

    In high material penetration by neutrons allows for experiments using sophisticated sample environments providing complex conditions. Thus, neutron imaging holds potential for performing in situ nondestructive measurements on large samples or even full technological systems, which are not possible with any other technique. Our paper presents a new sample environment for in situ high resolution neutron imaging experiments at temperatures from room temperature up to 1100 degrees C and/or using controllable flow of reactive atmospheres. The design also offers the possibility to directly combine imaging with diffraction measurements. Design, special features, and specification of the furnace are described. In addition, examples of experiments successfully performed at various neutron facilities with the furnace, as well as examples of possible applications are presented. Our work covers a broad field of research from fundamental to technological investigations of various types of materials and components.

  6. Temperature programmed desorption studies of water interactions with Apollo lunar samples 12001 and 72501

    NASA Astrophysics Data System (ADS)

    Poston, Michael J.; Grieves, Gregory A.; Aleksandrov, Alexandr B.; Hibbitts, Charles A.; Dyar, M. Darby; Orlando, Thomas M.

    2015-07-01

    The desorption activation energies for water molecules chemisorbed on Apollo lunar samples 72501 (highlands soil) and 12001 (mare soil) were determined by temperature programmed desorption experiments in ultra-high vacuum. A significant difference in both the energies and abundance of chemisorption sites was observed, with 72501 retaining up to 40 times more water (by mass) and with much stronger adsorption interactions, possibly approaching 1.5 eV. The dramatic difference between the samples may be due to differences in mineralogy and surface exposure age. The distribution function of water desorption activation energies for sample 72501 was used as an initial condition to simulate water persistence through a temperature profile matching the lunar day.

  7. Flexible sample environment for high resolution neutron imaging at high temperatures in controlled atmosphere.

    PubMed

    Makowska, Małgorzata G; Theil Kuhn, Luise; Cleemann, Lars N; Lauridsen, Erik M; Bilheux, Hassina Z; Molaison, Jamie J; Santodonato, Louis J; Tremsin, Anton S; Grosse, Mirco; Morgano, Manuel; Kabra, Saurabh; Strobl, Markus

    2015-12-01

    High material penetration by neutrons allows for experiments using sophisticated sample environments providing complex conditions. Thus, neutron imaging holds potential for performing in situ nondestructive measurements on large samples or even full technological systems, which are not possible with any other technique. This paper presents a new sample environment for in situ high resolution neutron imaging experiments at temperatures from room temperature up to 1100 °C and/or using controllable flow of reactive atmospheres. The design also offers the possibility to directly combine imaging with diffraction measurements. Design, special features, and specification of the furnace are described. In addition, examples of experiments successfully performed at various neutron facilities with the furnace, as well as examples of possible applications are presented. This covers a broad field of research from fundamental to technological investigations of various types of materials and components. PMID:26724075

  8. Flexible sample environment for high resolution neutron imaging at high temperatures in controlled atmosphere

    DOE PAGESBeta

    Makowska, Małgorzata G.; Theil Kuhn, Luise; Cleemann, Lars N.; Lauridsen, Erik M.; Bilheux, Hassina Z.; Molaison, Jamie J.; Santodonato, Louis J.; Tremsin, Anton S.; Grosse, Mirco; Morgano, Manuel; et al

    2015-12-17

    In high material penetration by neutrons allows for experiments using sophisticated sample environments providing complex conditions. Thus, neutron imaging holds potential for performing in situ nondestructive measurements on large samples or even full technological systems, which are not possible with any other technique. Our paper presents a new sample environment for in situ high resolution neutron imaging experiments at temperatures from room temperature up to 1100 degrees C and/or using controllable flow of reactive atmospheres. The design also offers the possibility to directly combine imaging with diffraction measurements. Design, special features, and specification of the furnace are described. In addition,more » examples of experiments successfully performed at various neutron facilities with the furnace, as well as examples of possible applications are presented. Our work covers a broad field of research from fundamental to technological investigations of various types of materials and components.« less

  9. Thermal mapping and trends of Mars analog materials in sample acquisition operations using experimentation and models

    NASA Astrophysics Data System (ADS)

    Szwarc, Timothy; Hubbard, Scott

    2014-09-01

    The effects of atmosphere, ambient temperature, and geologic material were studied experimentally and using a computer model to predict the heating undergone by Mars rocks during rover sampling operations. Tests were performed on five well-characterized and/or Mars analog materials: Indiana limestone, Saddleback basalt, kaolinite, travertine, and water ice. Eighteen tests were conducted to 55 mm depth using a Mars Sample Return prototype coring drill, with each sample containing six thermal sensors. A thermal simulation was written to predict the complete thermal profile within each sample during coring and this model was shown to be capable of predicting temperature increases with an average error of about 7%. This model may be used to schedule power levels and periods of rest during actual sample acquisition processes to avoid damaging samples or freezing the bit into icy formations. Maximum rock temperature increase is found to be modeled by a power law incorporating rock and operational parameters. Energy transmission efficiency in coring is found to increase linearly with rock hardness and decrease by 31% at Mars pressure.

  10. Effects and Mitigation of Clear Sky Sampling on Recorded Trends in Land Surface Temperature

    NASA Astrophysics Data System (ADS)

    Holmes, T. R.; Hain, C.; de Jeu, R.; Anderson, M. C.; Crow, W. T.

    2015-12-01

    Land surface temperature (LST) is a key input for physically-based retrieval algorithms of hydrological states and fluxes. Yet, it remains a poorly constrained parameter for global scale studies. The main two observational methods to remotely measure T are based on thermal infrared (TIR) observations and passive microwave observations (MW). TIR is the most commonly used approach and the method of choice to provide standard LST products for various satellite missions. MW-based LST retrievals on the other hand are not as widely adopted for land applications; currently their principle use is in soil moisture retrieval algorithms. MW and TIR technologies present two highly complementary and independent means of measuring LST. MW observations have a high tolerance to clouds but a low spatial resolution, and TIR has a high spatial resolution with temporal sampling restricted to clear skies. This paper builds on recent progress in characterizing the main structural differences between TIR LST and MW Ka-band observations, the MW frequency that is most suitable for LST sensing. By accounting for differences in diurnal timing (phase lag with solar noon), amplitude, and emissivity we construct a MW-based LST dataset that matches the diurnal characteristics of the TIR-based LSA SAF LST record. This new global dataset of MW-based LST currently spans the period of 2003-2013. In this paper we will present results of a validation of MW LST with in situ data with special emphasis on the effect of cloudiness on the performance. The ability to remotely sense the temperature of cloud covered land is what sets this MW-LST datasets apart from existing (much higher resolution) TIR-based products. As an example of this we will therefore explore how MW LST can mitigate the effect of clear-sky sampling in the context of trend and anomaly detection. We do this by contrasting monthly means of TIR-LST with its clear-sky and all-sky equivalent from an MW-LST and an NWP model.

  11. A Unimodal Model for Double Observer Distance Sampling Surveys

    PubMed Central

    Becker, Earl F.; Christ, Aaron M.

    2015-01-01

    Distance sampling is a widely used method to estimate animal population size. Most distance sampling models utilize a monotonically decreasing detection function such as a half-normal. Recent advances in distance sampling modeling allow for the incorporation of covariates into the distance model, and the elimination of the assumption of perfect detection at some fixed distance (usually the transect line) with the use of double-observer models. The assumption of full observer independence in the double-observer model is problematic, but can be addressed by using the point independence assumption which assumes there is one distance, the apex of the detection function, where the 2 observers are assumed independent. Aerially collected distance sampling data can have a unimodal shape and have been successfully modeled with a gamma detection function. Covariates in gamma detection models cause the apex of detection to shift depending upon covariate levels, making this model incompatible with the point independence assumption when using double-observer data. This paper reports a unimodal detection model based on a two-piece normal distribution that allows covariates, has only one apex, and is consistent with the point independence assumption when double-observer data are utilized. An aerial line-transect survey of black bears in Alaska illustrate how this method can be applied. PMID:26317984

  12. Characterization of Wafer-Level Au-In-Bonded Samples at Elevated Temperatures

    NASA Astrophysics Data System (ADS)

    Luu, Thi-Thuy; Hoivik, Nils; Wang, Kaiying; Aasmundtveit, Knut E.; Vardøy, Astrid-Sofie B.

    2015-06-01

    Wafer-level bonding using Au-In solid liquid interdiffusion (SLID) bonding is a promising approach to enable low-temperature assembly and MEMS packaging/encapsulation. Due to the low-melting point of In, wafer-level bonding can be performed at considerably lower temperatures than Sn-based bonding; this work treats bonds performed at 453 K (180 °C). Following bonding, the die shear strength at elevated temperatures was investigated from room temperature to 573 K (300 °C), revealing excellent mechanical integrity at these temperatures well above the bonding temperature. For shear test temperatures from room temperature to 473 K (200 °C), the measured shear strength was stable at 30 MPa, whereas it increased to 40 MPa at shear test temperature of 573 K (300 °C). The fracture surfaces of Au-In-bonded samples revealed brittle fracture modes (at the original bond interface and at the adhesion layers) for shear test temperatures up to 473 K (200 °C), but ductile fracture mode for shear test temperature of 573 K (300 °C). The as-bonded samples have a layered structure consisting of the two intermetallic phases AuIn and γ', as shown by cross section microscopy and predicted from the phase diagram. The change in behavior for the tests at 573 K (300 °C) is attributed to a solid-state phase transition occurring at 497 K (224 °C), where the phase diagram predicts a AuIn/ψ structure and a phase boundary moving across the initial bond interface. The associated interdiffusion of Au and In will strengthen the initial bond interface and, as a consequence, the measured shear strength. This work provides experimental evidence for the high-temperature stability of wafer-level, low-temperature bonded, Au-In SLID bonds. The high bond strength obtained is limited by the strength at the initial bond interface and at the adhesion layers, showing that the Au-In SLID system itself is capable of even higher bond strength.

  13. Dynamical models of a sample of Population II stars

    NASA Astrophysics Data System (ADS)

    Levison, H. F.; Richstone, D. O.

    1986-09-01

    Dynamical models are constructed in order to investigate the implications of recent kinematic data of distant Population II stars on the emissivity distribution of those stars. Models are constructed using a modified Schwarzschild method in two extreme scale-free potentials, spherical and E6 elliptical. Both potentials produce flat rotation curves and velocity dispersion profiles. In all models, the distribution of stars in this sample is flat. Moreover, it is not possible to construct a model with a strictly spheroidal emissivity distribution. Most models have dimples at the poles. The dynamics of the models indicate that the system is supported by both the third integral and z angular momentum.

  14. Small Sample Properties of Bayesian Multivariate Autoregressive Time Series Models

    ERIC Educational Resources Information Center

    Price, Larry R.

    2012-01-01

    The aim of this study was to compare the small sample (N = 1, 3, 5, 10, 15) performance of a Bayesian multivariate vector autoregressive (BVAR-SEM) time series model relative to frequentist power and parameter estimation bias. A multivariate autoregressive model was developed based on correlated autoregressive time series vectors of varying…

  15. Bayesian Estimation of the DINA Model with Gibbs Sampling

    ERIC Educational Resources Information Center

    Culpepper, Steven Andrew

    2015-01-01

    A Bayesian model formulation of the deterministic inputs, noisy "and" gate (DINA) model is presented. Gibbs sampling is employed to simulate from the joint posterior distribution of item guessing and slipping parameters, subject attribute parameters, and latent class probabilities. The procedure extends concepts in Béguin and Glas,…

  16. Sample size calculation for the proportional hazards cure model.

    PubMed

    Wang, Songfeng; Zhang, Jiajia; Lu, Wenbin

    2012-12-20

    In clinical trials with time-to-event endpoints, it is not uncommon to see a significant proportion of patients being cured (or long-term survivors), such as trials for the non-Hodgkins lymphoma disease. The popularly used sample size formula derived under the proportional hazards (PH) model may not be proper to design a survival trial with a cure fraction, because the PH model assumption may be violated. To account for a cure fraction, the PH cure model is widely used in practice, where a PH model is used for survival times of uncured patients and a logistic distribution is used for the probability of patients being cured. In this paper, we develop a sample size formula on the basis of the PH cure model by investigating the asymptotic distributions of the standard weighted log-rank statistics under the null and local alternative hypotheses. The derived sample size formula under the PH cure model is more flexible because it can be used to test the differences in the short-term survival and/or cure fraction. Furthermore, we also investigate as numerical examples the impacts of accrual methods and durations of accrual and follow-up periods on sample size calculation. The results show that ignoring the cure rate in sample size calculation can lead to either underpowered or overpowered studies. We evaluate the performance of the proposed formula by simulation studies and provide an example to illustrate its application with the use of data from a melanoma trial. PMID:22786805

  17. Headspace-programmed temperature vaporizer-mass spectrometry and pattern recognition techniques for the analysis of volatiles in saliva samples.

    PubMed

    Pérez Antón, Ana; Del Nogal Sánchez, Miguel; Crisolino Pozas, Ángel Pedro; Pérez Pavón, José Luis; Moreno Cordero, Bernardo

    2016-11-01

    A rapid method for the analysis of volatiles in saliva samples is proposed. The method is based on direct coupling of three components: a headspace sampler (HS), a programmable temperature vaporizer (PTV) and a quadrupole mass spectrometer (qMS). Several applications in the biomedical field have been proposed with electronic noses based on different sensors. However, few contributions have been developed using a mass spectrometry-based electronic nose in this field up to date. Samples of 23 patients with some type of cancer and 32 healthy volunteers were analyzed with HS-PTV-MS and the profile signals obtained were subjected to pattern recognition techniques with the aim of studying the possibilities of the methodology to differentiate patients with cancer from healthy controls. An initial inspection of the contained information in the data by means of principal components analysis (PCA) revealed a complex situation were an overlapped distribution of samples in the score plot was visualized instead of two groups of separated samples. Models using K-nearest neighbors (KNN) and Soft Independent Modeling of Class Analogy (SIMCA) showed poor discrimination, specially using SIMCA where a small distance between classes was obtained and no satisfactory results in the classification of the external validation samples were achieved. Good results were obtained when Mahalanobis discriminant analysis (DA) and support vector machines (SVM) were used obtaining 2 (false positives) and 0 samples misclassified in the external validation set, respectively. No false negatives were found using these techniques. PMID:27591583

  18. Importance of sample form and surface temperature for analysis by ambient plasma mass spectrometry (PADI).

    PubMed

    Salter, Tara La Roche; Bunch, Josephine; Gilmore, Ian S

    2014-09-16

    Many different types of samples have been analyzed in the literature using plasma-based ambient mass spectrometry sources; however, comprehensive studies of the important parameters for analysis are only just beginning. Here, we investigate the effect of the sample form and surface temperature on the signal intensities in plasma-assisted desorption ionization (PADI). The form of the sample is very important, with powders of all volatilities effectively analyzed. However, for the analysis of thin films at room temperature and using a low plasma power, a vapor pressure of greater than 10(-4) Pa is required to achieve a sufficiently good quality spectrum. Using thermal desorption, we are able to increase the signal intensity of less volatile materials with vapor pressures less than 10(-4) Pa, in thin film form, by between 4 and 7 orders of magnitude. This is achieved by increasing the temperature of the sample up to a maximum of 200 °C. Thermal desorption can also increase the signal intensity for the analysis of powders. PMID:25137443

  19. Development of an Integrated Thermocouple for the Accurate Sample Temperature Measurement During High Temperature Environmental Scanning Electron Microscopy (HT-ESEM) Experiments.

    PubMed

    Podor, Renaud; Pailhon, Damien; Ravaux, Johann; Brau, Henri-Pierre

    2015-04-01

    We have developed two integrated thermocouple (TC) crucible systems that allow precise measurement of sample temperature when using a furnace associated with an environmental scanning electron microscope (ESEM). Sample temperatures measured with these systems are precise (±5°C) and reliable. The TC crucible systems allow working with solids and liquids (silicate melts or ionic liquids), independent of the gas composition and pressure. These sample holder designs will allow end users to perform experiments at high temperature in the ESEM chamber with high precision control of the sample temperature. PMID:25898837

  20. Sampling artifact in volume weighted velocity measurement. I. Theoretical modeling

    NASA Astrophysics Data System (ADS)

    Zhang, Pengjie; Zheng, Yi; Jing, Yipeng

    2015-02-01

    Cosmology based on large scale peculiar velocity prefers volume weighted velocity statistics. However, measuring the volume weighted velocity statistics from inhomogeneously distributed galaxies (simulation particles/halos) suffers from an inevitable and significant sampling artifact. We study this sampling artifact in the velocity power spectrum measured by the nearest particle velocity assignment method by Zheng et al., [Phys. Rev. D 88, 103510 (2013).]. We derive the analytical expression of leading and higher order terms. We find that the sampling artifact suppresses the z =0 E -mode velocity power spectrum by ˜10 % at k =0.1 h /Mpc , for samples with number density 10-3 (Mpc /h )-3 . This suppression becomes larger for larger k and for sparser samples. We argue that this source of systematic errors in peculiar velocity cosmology, albeit severe, can be self-calibrated in the framework of our theoretical modelling. We also work out the sampling artifact in the density-velocity cross power spectrum measurement. A more robust evaluation of related statistics through simulations will be presented in a companion paper by Zheng et al., [Sampling artifact in volume weighted velocity measurement. II. Detection in simulations and comparison with theoretical modelling, arXiv:1409.6809.]. We also argue that similar sampling artifact exists in other velocity assignment methods and hence must be carefully corrected to avoid systematic bias in peculiar velocity cosmology.

  1. Sampling theory applied to measurement and analysis of temperature for climate studies

    NASA Technical Reports Server (NTRS)

    Edwards, Howard B.

    1987-01-01

    Of all the errors discussed in climatology literature, aliasing errors caused by undersampling of unsmoothed or improperly smoothed temperature data seem to be completely overlooked. This is a serious oversight in view of long-term trends of 1 K or less. Adequate sampling of properly smoothed data is demonstrated with a Hamming digital filter. It is also demonstrated that hourly temperatures, daily averages, and annual averages free of aliasing errors can be obtained by use of a microprocessor added to standard weather sensors and recorders.

  2. Integrated research in constitutive modelling at elevated temperatures, part 1

    NASA Technical Reports Server (NTRS)

    Haisler, W. E.; Allen, D. H.

    1986-01-01

    Topics covered include: numerical integration techniques; thermodynamics and internal state variables; experimental lab development; comparison of models at room temperature; comparison of models at elevated temperature; and integrated software development.

  3. Optimizing the Operating Temperature for an array of MOX Sensors on an Open Sampling System

    NASA Astrophysics Data System (ADS)

    Trincavelli, M.; Vergara, A.; Rulkov, N.; Murguia, J. S.; Lilienthal, A.; Huerta, R.

    2011-09-01

    Chemo-resistive transduction is essential for capturing the spatio-temporal structure of chemical compounds dispersed in different environments. Due to gas dispersion mechanisms, namely diffusion, turbulence and advection, the sensors in an open sampling system, i.e. directly exposed to the environment to be monitored, are exposed to low concentrations of gases with many fluctuations making, as a consequence, the identification and monitoring of the gases even more complicated and challenging than in a controlled laboratory setting. Therefore, tuning the value of the operating temperature becomes crucial for successfully identifying and monitoring the pollutant gases, particularly in applications such as exploration of hazardous areas, air pollution monitoring, and search and rescue1. In this study we demonstrate the benefit of optimizing the sensor's operating temperature when the sensors are deployed in an open sampling system, i.e. directly exposed to the environment to be monitored.

  4. Impact of multicollinearity on small sample hydrologic regression models

    NASA Astrophysics Data System (ADS)

    Kroll, Charles N.; Song, Peter

    2013-06-01

    Often hydrologic regression models are developed with ordinary least squares (OLS) procedures. The use of OLS with highly correlated explanatory variables produces multicollinearity, which creates highly sensitive parameter estimators with inflated variances and improper model selection. It is not clear how to best address multicollinearity in hydrologic regression models. Here a Monte Carlo simulation is developed to compare four techniques to address multicollinearity: OLS, OLS with variance inflation factor screening (VIF), principal component regression (PCR), and partial least squares regression (PLS). The performance of these four techniques was observed for varying sample sizes, correlation coefficients between the explanatory variables, and model error variances consistent with hydrologic regional regression models. The negative effects of multicollinearity are magnified at smaller sample sizes, higher correlations between the variables, and larger model error variances (smaller R2). The Monte Carlo simulation indicates that if the true model is known, multicollinearity is present, and the estimation and statistical testing of regression parameters are of interest, then PCR or PLS should be employed. If the model is unknown, or if the interest is solely on model predictions, is it recommended that OLS be employed since using more complicated techniques did not produce any improvement in model performance. A leave-one-out cross-validation case study was also performed using low-streamflow data sets from the eastern United States. Results indicate that OLS with stepwise selection generally produces models across study regions with varying levels of multicollinearity that are as good as biased regression techniques such as PCR and PLS.

  5. An open-population hierarchical distance sampling model

    USGS Publications Warehouse

    Sollmann, Rachel; Beth Gardner; Richard B Chandler; Royle, J. Andrew; T Scott Sillett

    2015-01-01

    Modeling population dynamics while accounting for imperfect detection is essential to monitoring programs. Distance sampling allows estimating population size while accounting for imperfect detection, but existing methods do not allow for direct estimation of demographic parameters. We develop a model that uses temporal correlation in abundance arising from underlying population dynamics to estimate demographic parameters from repeated distance sampling surveys. Using a simulation study motivated by designing a monitoring program for island scrub-jays (Aphelocoma insularis), we investigated the power of this model to detect population trends. We generated temporally autocorrelated abundance and distance sampling data over six surveys, using population rates of change of 0.95 and 0.90. We fit the data generating Markovian model and a mis-specified model with a log-linear time effect on abundance, and derived post hoc trend estimates from a model estimating abundance for each survey separately. We performed these analyses for varying number of survey points. Power to detect population changes was consistently greater under the Markov model than under the alternatives, particularly for reduced numbers of survey points. The model can readily be extended to more complex demographic processes than considered in our simulations. This novel framework can be widely adopted for wildlife population monitoring.

  6. Characterization of Decommissioned PWR Vessel Internals Materials Samples: Material Certification, Fluence, and Temperature (Nonproprietary Version)

    SciTech Connect

    M. Krug; R. Shogan; A. Fero; M. Snyder

    2004-11-01

    Pressurized water reactor (PWR) cores, operate under extreme environmental conditions due to coolant chemistry, operating temperature, and neutron exposure. Extending the life of PWRs require detailed knowledge of the changes in mechanical and corrosion properties of the structural austenitic stainless steel components adjacent to the fuel. This report contains basic material characterization information of the as-installed samples of reactor internals material which were harvested from a decommissioned PWR.

  7. Colour matching of isoluminant samples and backgrounds: a model.

    PubMed

    Stanikunas, Rytis; Vaitkevicius, Henrikas; Kulikowski, Janus J; Murray, Ian J; Daugirdiene, Avsra

    2005-01-01

    A cone-opponent-based vector model is used to derive the activity in the red-green, yellow-blue, and achromatic channels during a sequential asymmetric colour-matching experiment. Forty Munsell samples, simulated under illuminant C, were matched with their appearance under eight test illuminants. The test samples and backgrounds were photometrically isoluminant with each other. According to the model, the orthogonality of the channels is revealed when test illuminants lie along either red-green or yellow blue cardinal axes. The red green and yellow-blue outputs of the channels are described in terms of the hue of the sample. The fact that the three-channel model explains the data in a colour-matching experiment indicates that an early form of colour processing is mediated at a site where the three channels converge, probably the input layer of V1. PMID:16178154

  8. Operating parameters of liquid helium transfer lines used with continuous flow cryostats at low sample temperatures

    NASA Astrophysics Data System (ADS)

    Dittmar, N.; Welker, D.; Haberstroh, Ch; Hesse, U.; Krzyzowski, M.

    2015-12-01

    Continuous flow cryostats are used to cool samples to a variable temperature level by evaporating a cryogen, e.g. liquid helium (LHe). For this purpose LHe is usually stored outside the cryostat in a mobile dewar and supplied through a transfer line. In general, the complete setup has to be characterised by the lowest possible consumption of LHe. Additionally, a minimum sample temperature can be favourable from an experimental point of view. The achievement of both requirements is determined by the respective cryostat design as well as by the transfer line. In the presented work operating data, e.g. the LHe consumption during cooldown and steady state, the minimum sample temperature, and the outlet quality are analysed to characterise the performance of a reference transfer line. In addition, an experimental transfer line with built-in pressure sensors has been commissioned to examine the pressure drop along the transfer line, too. During the tests LHe impurities occurred which restricted a steady operation.

  9. Effect of vacuum packing and temperature on survival and hatching of strongyle eggs in faecal samples.

    PubMed

    Sengupta, Mita E; Thapa, Sundar; Thamsborg, Stig M; Mejer, Helena

    2016-02-15

    Strongyle eggs of helminths of livestock usually hatch within a few hours or days after deposition with faeces. This poses a problem when faecal sampling is performed in the field. As oxygen is needed for embryonic development, it is recommended to reduce air supply during transport and refrigerate. The present study therefore investigated the combined effect of vacuum packing and temperature on survival of strongyle eggs and their subsequent ability to hatch and develop into L3. Fresh faecal samples were collected from calves infected with Cooperia oncophora, pigs infected with Oesophagostomum dentatum, and horses infected with Strongylus vulgaris and cyathostomins. The samples were allocated into four treatments: vacuum packing and storage at 5 °C or 20 °C (5 V and 20 V); normal packing in plastic gloves closed with a loose knot and storage at 5 °C or 20 °C (5 N and 20 N). The number of eggs per gram faeces (EPG) was estimated every fourth day until day 28 post set up (p.s.) by a concentration McMaster-method. Larval cultures were prepared on day 0, 12 and 28 p.s. and the larval yield determined. For C. oncophora, the EPG was significantly higher in vacuum packed samples after 28 days as compared to normal storage, regardless of temperature. However, O. dentatum EPG was significantly higher in samples kept at 5 °C as compared to 20 °C, irrespective of packing. For the horse strongyles, vacuum packed samples at 5 °C had a significantly higher EPG compared to the other treatments after 28 days. The highest larval yield of O. dentatum and horse strongyles were obtained from fresh faecal samples, however, if storage is necessary prior to setting up larval cultures O. dentatum should be kept at room temperature (aerobic or anaerobic). However, horse strongyle coprocultures should ideally be set up on the day of collection to ensure maximum yield. Eggs of C. oncophora should be kept vacuum packed at room temperature for the highest larval yield. PMID:26827855

  10. The effect of low-temperature demagnetization on paleointensity determinations from samples with different domain states

    NASA Astrophysics Data System (ADS)

    Kulakov, E.; Smirnov, A. V.

    2013-05-01

    It has been recently proposed that incorporation of low-temperature demagnetization (LTD) into the Thellier double-heating method increases the accuracy and success rate of paleointensity experiments by reducing the effects of magnetic remanence carried by large pseudo-singledomain (PSD) and multidomain (MD) grains (e.g., Celino et al., Geophysical Research Letters, 34, L12306, 2007). However, it has been unclear to what degree the LTD affects the remanence carried by single-domain (SD) and small PSD. To investigate this problem, we carried out paleointensity experiments on synthetic magnetite-bearing samples containing nearly SD, PSD, and multidomain MD grains as well as mixtures of MD and SD grains. Before the experiments, a thermal remanent magnetization was imparted to the samples in a known laboratory field. Paleointensities were determined using both the LTD-Thellier and multi-specimen parallel pTRM methods. The samples were subjected to a series of three LTD treatments in liquid nitrogen after each heating. LTD significantly improved the quality of paleointensity determinations from the samples containing large PSD and MD magnetite as well as SD-MD mixtures. In particular, LTD resulted in a significant increase of the paleointensity quality factor, producing more linear Arai plots and reducing data scatter. In addition, field intensities calculated after LTD fell within 2-4% of the known laboratory field. On the other hand, the effect of LTD on paleointensity determinations from samples with nearly SD magnetite is negligible. Paleointensity values based on both pre- and post-LTD data were statistically indistinguishable of the laboratory field. LTD treatment significantly reduced the systematic paleofield overestimation using the multi-specimen method from samples containing PSD and MD grains, as well as SD-MD mixtures. The results of multi-specimen paleointensity experiments performed on the PSD and MD samples using different heating temperatures suggest

  11. Fluorescence of commercial Pluronic F127 samples: Temperature-dependent micellization.

    PubMed

    Perry, Christopher C; Sabir, Theodore S; Livingston, Wesley J; Milligan, Jamie R; Chen, Qiao; Maskiewicz, Victoria; Boskovic, Danilo S

    2011-02-15

    We present a novel approach of using the butylated hydroxytoluene (BHT) antioxidant found in commercial Pluronic F127 samples as a marker of polymer aggregation. The BHT marker was compared to the pyrene dye and static light scattering methods as a way to measure the critical micelle concentration (CMC) and critical micelle temperature (CMT). The n→π(∗) transitions of BHT are sensitive to the microenvironment as demonstrated by plotting the fractional intensities of its excitation (≈280nm) and emission (≈325nm) peaks. BHT is more sensitive to changes in temperature than concentration. The partition coefficient increases ≈40-fold for pyrene compared to ≈2-fold for BHT when the temperature is increased from 25 to 37°C. CMT values determined using the BHT fluorescence decrease with increasing F127 concentration. Our results show that BHT can be used as a reliable marker of changes in the microenvironment of Pluronic F127. PMID:21087773

  12. Accelerating the Convergence of Replica Exchange Simulations Using Gibbs Sampling and Adaptive Temperature Sets

    DOE PAGESBeta

    Vogel, Thomas; Perez, Danny

    2015-08-28

    We recently introduced a novel replica-exchange scheme in which an individual replica can sample from states encountered by other replicas at any previous time by way of a global configuration database, enabling the fast propagation of relevant states through the whole ensemble of replicas. This mechanism depends on the knowledge of global thermodynamic functions which are measured during the simulation and not coupled to the heat bath temperatures driving the individual simulations. Therefore, this setup also allows for a continuous adaptation of the temperature set. In this paper, we will review the new scheme and demonstrate its capability. The methodmore » is particularly useful for the fast and reliable estimation of the microcanonical temperature T (U) or, equivalently, of the density of states g(U) over a wide range of energies.« less

  13. Accelerating the Convergence of Replica Exchange Simulations Using Gibbs Sampling and Adaptive Temperature Sets

    SciTech Connect

    Vogel, Thomas; Perez, Danny

    2015-08-28

    We recently introduced a novel replica-exchange scheme in which an individual replica can sample from states encountered by other replicas at any previous time by way of a global configuration database, enabling the fast propagation of relevant states through the whole ensemble of replicas. This mechanism depends on the knowledge of global thermodynamic functions which are measured during the simulation and not coupled to the heat bath temperatures driving the individual simulations. Therefore, this setup also allows for a continuous adaptation of the temperature set. In this paper, we will review the new scheme and demonstrate its capability. The method is particularly useful for the fast and reliable estimation of the microcanonical temperature T (U) or, equivalently, of the density of states g(U) over a wide range of energies.

  14. Analytic Models of High-Temperature Hohlraums

    SciTech Connect

    Stygar, W.A.; Olson, R.E.; Spielman, R.B.; Leeper, R.J.

    2000-11-29

    A unified set of high-temperature-hohlraum models has been developed. For a simple hohlraum, P{sub s} = [A{sub s}+(1{minus}{alpha}{sub W})A{sub W}+A{sub H}]{sigma}T{sub R}{sup 4} + (4V{sigma}/c)(dT{sub R}{sup r}/dt) where P{sub S} is the total power radiated by the source, A{sub s} is the source area, A{sub W} is the area of the cavity wall excluding the source and holes in the wall, A{sub H} is the area of the holes, {sigma} is the Stefan-Boltzmann constant, T{sub R} is the radiation brightness temperature, V is the hohlraum volume, and c is the speed of light. The wall albedo {alpha}{sub W} {triple_bond} (T{sub W}/T{sub R}){sup 4} where T{sub W} is the brightness temperature of area A{sub W}. The net power radiated by the source P{sub N} = P{sub S}-A{sub S}{sigma}T{sub R}{sup 4}, which suggests that for laser-driven hohlraums the conversion efficiency {eta}{sub CE} be defined as P{sub N}/P{sub LASER}. The characteristic time required to change T{sub R}{sup 4} in response to a change in P{sub N} is 4V/C[(l{minus}{alpha}{sub W})A{sub W}+A{sub H}]. Using this model, T{sub R}, {alpha}{sub W}, and {eta}{sub CE} can be expressed in terms of quantities directly measurable in a hohlraum experiment. For a steady-state hohlraum that encloses a convex capsule, P{sub N} = {l_brace}(1{minus}{alpha}{sub W})A{sub W}+A{sub H}+[(1{minus}{alpha}{sub C})(A{sub S}+A{sub W}{alpha}{sub W})A{sub C}/A{sub T}]{r_brace}{sigma}T{sub RC}{sup 4} where {alpha}{sub C} is the capsule albedo, A{sub C} is the capsule area, A{sub T} {triple_bond} (A{sub S}+A{sub W}+A{sub H}), and T{sub RC} is the brightness temperature of the radiation that drives the capsule. According to this relation, the capsule-coupling efficiency of the baseline National-Ignition-Facility (NIF) hohlraum is 15% higher than predicted by previous analytic expressions. A model of a hohlraum that encloses a z pinch is also presented.

  15. Helium flow and temperatures in a heated sample of a final ITER TF cable-in-conduit conductor

    NASA Astrophysics Data System (ADS)

    Herzog, Robert; Lewandowska, Monika; Calvi, Marco; Bessette, Denis

    2010-06-01

    The quest for a detailed understanding of the thermo-hydraulic behaviour of the helium flow in the dual-channel cable-in-conduit conductor (CICC) for the ITER toroidal-field coils led to a series of experiments in the SULTAN test facility on a dedicated sample made according to the final conductor design. With helium flowing through the conductor as expected during ITER operation, the sample was heated by eddy-current losses induced in the strands by an applied AC magnetic field as well as by foil heaters mounted on the outside of the conductor jacket. Temperature sensors mounted on the jacket surface, in the central channel and at different radii in the sub-cable region showed the longitudinal as well as radial temperature distribution at different mass flow rates and heat loads. Spot heaters in the bundle and the central channel created small heated helium regions, which were detected downstream by a series of temperature sensors. With a time-of-flight method the helium velocity could thus be determined independently of any flow model. The temperature and velocity distributions in bundle and central channel under different mass-flow and heat load conditions thus led to a detailed picture of the helium flow in the final ITER TF CICCs.

  16. On species sampling sequences induced by residual allocation models

    PubMed Central

    Rodríguez, Abel; Quintana, Fernando A.

    2014-01-01

    We discuss fully Bayesian inference in a class of species sampling models that are induced by residual allocation (sometimes called stick-breaking) priors on almost surely discrete random measures. This class provides a generalization of the well-known Ewens sampling formula that allows for additional flexibility while retaining computational tractability. In particular, the procedure is used to derive the exchangeable predictive probability functions associated with the generalized Dirichlet process of Hjort (2000) and the probit stick-breaking prior of Chung and Dunson (2009) and Rodriguez and Dunson (2011). The procedure is illustrated with applications to genetics and nonparametric mixture modeling. PMID:25477705

  17. On species sampling sequences induced by residual allocation models.

    PubMed

    Rodríguez, Abel; Quintana, Fernando A

    2015-02-01

    We discuss fully Bayesian inference in a class of species sampling models that are induced by residual allocation (sometimes called stick-breaking) priors on almost surely discrete random measures. This class provides a generalization of the well-known Ewens sampling formula that allows for additional flexibility while retaining computational tractability. In particular, the procedure is used to derive the exchangeable predictive probability functions associated with the generalized Dirichlet process of Hjort (2000) and the probit stick-breaking prior of Chung and Dunson (2009) and Rodriguez and Dunson (2011). The procedure is illustrated with applications to genetics and nonparametric mixture modeling. PMID:25477705

  18. Geostatistical modeling of riparian forest microclimate and its implications for sampling

    USGS Publications Warehouse

    Eskelson, B.N.I.; Anderson, P.D.; Hagar, J.C.; Temesgen, H.

    2011-01-01

    Predictive models of microclimate under various site conditions in forested headwater stream - riparian areas are poorly developed, and sampling designs for characterizing underlying riparian microclimate gradients are sparse. We used riparian microclimate data collected at eight headwater streams in the Oregon Coast Range to compare ordinary kriging (OK), universal kriging (UK), and kriging with external drift (KED) for point prediction of mean maximum air temperature (Tair). Several topographic and forest structure characteristics were considered as site-specific parameters. Height above stream and distance to stream were the most important covariates in the KED models, which outperformed OK and UK in terms of root mean square error. Sample patterns were optimized based on the kriging variance and the weighted means of shortest distance criterion using the simulated annealing algorithm. The optimized sample patterns outperformed systematic sample patterns in terms of mean kriging variance mainly for small sample sizes. These findings suggest methods for increasing efficiency of microclimate monitoring in riparian areas.

  19. Effect of short-term room temperature storage on the microbial community in infant fecal samples

    PubMed Central

    Guo, Yong; Li, Sheng-Hui; Kuang, Ya-Shu; He, Jian-Rong; Lu, Jin-Hua; Luo, Bei-Jun; Jiang, Feng-Ju; Liu, Yao-Zhong; Papasian, Christopher J.; Xia, Hui-Min; Deng, Hong-Wen; Qiu, Xiu

    2016-01-01

    Sample storage conditions are important for unbiased analysis of microbial communities in metagenomic studies. Specifically, for infant gut microbiota studies, stool specimens are often exposed to room temperature (RT) conditions prior to analysis. This could lead to variations in structural and quantitative assessment of bacterial communities. To estimate such effects of RT storage, we collected feces from 29 healthy infants (0–3 months) and partitioned each sample into 5 portions to be stored for different lengths of time at RT before freezing at −80 °C. Alpha diversity did not differ between samples with storage time from 0 to 2 hours. The UniFrac distances and microbial composition analysis showed significant differences by testing among individuals, but not by testing between different time points at RT. Changes in the relative abundance of some specific (less common, minor) taxa were still found during storage at room temperature. Our results support previous studies in children and adults, and provided useful information for accurate characterization of infant gut microbiomes. In particular, our study furnished a solid foundation and justification for using fecal samples exposed to RT for less than 2 hours for comparative analyses between various medical conditions. PMID:27226242

  20. Compact low temperature scanning tunneling microscope with in-situ sample preparation capability.

    PubMed

    Kim, Jungdae; Nam, Hyoungdo; Qin, Shengyong; Kim, Sang-ui; Schroeder, Allan; Eom, Daejin; Shih, Chih-Kang

    2015-09-01

    We report on the design of a compact low temperature scanning tunneling microscope (STM) having in-situ sample preparation capability. The in-situ sample preparation chamber was designed to be compact allowing quick transfer of samples to the STM stage, which is ideal for preparing temperature sensitive samples such as ultra-thin metal films on semiconductor substrates. Conventional spring suspensions on the STM head often cause mechanical issues. To address this problem, we developed a simple vibration damper consisting of welded metal bellows and rubber pads. In addition, we developed a novel technique to ensure an ultra-high-vacuum (UHV) seal between the copper and stainless steel, which provides excellent reliability for cryostats operating in UHV. The performance of the STM was tested from 2 K to 77 K by using epitaxial thin Pb films on Si. Very high mechanical stability was achieved with clear atomic resolution even when using cryostats operating at 77 K. At 2 K, a clean superconducting gap was observed, and the spectrum was easily fit using the BCS density of states with negligible broadening. PMID:26429448

  1. Effect of short-term room temperature storage on the microbial community in infant fecal samples.

    PubMed

    Guo, Yong; Li, Sheng-Hui; Kuang, Ya-Shu; He, Jian-Rong; Lu, Jin-Hua; Luo, Bei-Jun; Jiang, Feng-Ju; Liu, Yao-Zhong; Papasian, Christopher J; Xia, Hui-Min; Deng, Hong-Wen; Qiu, Xiu

    2016-01-01

    Sample storage conditions are important for unbiased analysis of microbial communities in metagenomic studies. Specifically, for infant gut microbiota studies, stool specimens are often exposed to room temperature (RT) conditions prior to analysis. This could lead to variations in structural and quantitative assessment of bacterial communities. To estimate such effects of RT storage, we collected feces from 29 healthy infants (0-3 months) and partitioned each sample into 5 portions to be stored for different lengths of time at RT before freezing at -80 °C. Alpha diversity did not differ between samples with storage time from 0 to 2 hours. The UniFrac distances and microbial composition analysis showed significant differences by testing among individuals, but not by testing between different time points at RT. Changes in the relative abundance of some specific (less common, minor) taxa were still found during storage at room temperature. Our results support previous studies in children and adults, and provided useful information for accurate characterization of infant gut microbiomes. In particular, our study furnished a solid foundation and justification for using fecal samples exposed to RT for less than 2 hours for comparative analyses between various medical conditions. PMID:27226242

  2. Compact low temperature scanning tunneling microscope with in-situ sample preparation capability

    SciTech Connect

    Kim, Jungdae; Nam, Hyoungdo; Schroeder, Allan; Shih, Chih-Kang; Qin, Shengyong; Kim, Sang-ui; Eom, Daejin

    2015-09-15

    We report on the design of a compact low temperature scanning tunneling microscope (STM) having in-situ sample preparation capability. The in-situ sample preparation chamber was designed to be compact allowing quick transfer of samples to the STM stage, which is ideal for preparing temperature sensitive samples such as ultra-thin metal films on semiconductor substrates. Conventional spring suspensions on the STM head often cause mechanical issues. To address this problem, we developed a simple vibration damper consisting of welded metal bellows and rubber pads. In addition, we developed a novel technique to ensure an ultra-high-vacuum (UHV) seal between the copper and stainless steel, which provides excellent reliability for cryostats operating in UHV. The performance of the STM was tested from 2 K to 77 K by using epitaxial thin Pb films on Si. Very high mechanical stability was achieved with clear atomic resolution even when using cryostats operating at 77 K. At 2 K, a clean superconducting gap was observed, and the spectrum was easily fit using the BCS density of states with negligible broadening.

  3. Compact low temperature scanning tunneling microscope with in-situ sample preparation capability

    NASA Astrophysics Data System (ADS)

    Kim, Jungdae; Nam, Hyoungdo; Qin, Shengyong; Kim, Sang-ui; Schroeder, Allan; Eom, Daejin; Shih, Chih-Kang

    2015-09-01

    We report on the design of a compact low temperature scanning tunneling microscope (STM) having in-situ sample preparation capability. The in-situ sample preparation chamber was designed to be compact allowing quick transfer of samples to the STM stage, which is ideal for preparing temperature sensitive samples such as ultra-thin metal films on semiconductor substrates. Conventional spring suspensions on the STM head often cause mechanical issues. To address this problem, we developed a simple vibration damper consisting of welded metal bellows and rubber pads. In addition, we developed a novel technique to ensure an ultra-high-vacuum (UHV) seal between the copper and stainless steel, which provides excellent reliability for cryostats operating in UHV. The performance of the STM was tested from 2 K to 77 K by using epitaxial thin Pb films on Si. Very high mechanical stability was achieved with clear atomic resolution even when using cryostats operating at 77 K. At 2 K, a clean superconducting gap was observed, and the spectrum was easily fit using the BCS density of states with negligible broadening.

  4. New high temperature plasmas and sample introduction systems for analytical atomic emission and mass spectrometry

    SciTech Connect

    Montaser, A.

    1990-01-01

    In this project, new high temperature plasmas and new sample introduction systems are developed for rapid elemental and isotopic analysis of gases, solutions, and solids using atomic emission spectrometry (AES) and mass spectrometry (MS). These devices offer promise of solving singularly difficult analytical problems that either exist now or are likely to arise in the future in the various fields of energy generation, environmental pollution, biomedicine and nutrition. Emphasis is being placed on: generation of annular, helium inductively coupled plasmas (He ICPs) that are suitable for atomization, excitation, and ionization of elements possessing high excitation and ionization energies, with the intent of enhancing the detecting powers of a number of elements; diagnostic studies of high-temperature plasmas to quantify their fundamental properties, with the ultimate aim to improve analytical performance of atomic spectrometry; development and characterization of new sample introduction systems that consume microliter or microgram quantities of samples, and investigation of new membrane separators for striping solvent from sample aerosol to reduce various interferences and to enhance sensitivity in plasma spectrometry.

  5. Modelling LARES temperature distribution and thermal drag

    NASA Astrophysics Data System (ADS)

    Nguyen, Phuc H.; Matzner, Richard

    2015-10-01

    The LARES satellite, a laser-ranged space experiment to contribute to geophysics observation, and to measure the general relativistic Lense-Thirring effect, has been observed to undergo an anomalous along-track orbital acceleration of -0.4 pm/s2 (pm : = picometer). This thermal "drag" is not surprising; along-track thermal drag has previously been observed with the related LAGEOS satellites (-3.4 pm/s2). It is hypothesized that the thermal drag is principally due to anisotropic thermal radiation from the satellite's exterior. We report the results of numerical computations of the along-track orbital decay of the LARES satellite during the first 126 days after launch. The results depend to a significant degree on the visual and IR absorbance α and emissivity ɛ of the fused silica Cube Corner Reflectors. We present results for two values of α IR = ɛ IR : 0.82, a standard number for "clean" fused silica; and 0.60, a possible value for silica with slight surface contamination subjected to the space environment. The heating and the resultant along-track acceleration depend on the plane of the orbit, the sun position, and, in particular, on the occurrence of eclipses, all of which are functions of time. Thus we compute the thermal drag for specific days. We compare our model to observational data, available for a 120 day period starting with the 7th day after launch, which shows the average acceleration of -0.4 pm/s2. With our model the average along-track thermal drag over this 120 day period for CCR α IR = ɛ IR = 0.82 was computed to be -0.59 pm/s2. For CCR α IR = ɛ IR = 0.60 we compute -0.36 pm/s2. LARES consists of a solid spherical tungsten sphere, into which the CCRs are set in colatitude circles. Our calculation models the satellite as 93 isothermal elements: the tungsten part, and each of the 92 Cube Corner Reflectors. The satellite is heated from two sources: sunlight and Earth's infrared (IR) radiation. We work in the fast-spin regime, where CCRs with

  6. Multiple sample characterization of coals and other substances by controlled-atmosphere programmed temperature oxidation

    DOEpatents

    LaCount, Robert B.

    1993-01-01

    A furnace with two hot zones holds multiple analysis tubes. Each tube has a separable sample-packing section positioned in the first hot zone and a catalyst-packing section positioned in the second hot zone. A mass flow controller is connected to an inlet of each sample tube, and gas is supplied to the mass flow controller. Oxygen is supplied through a mass flow controller to each tube to either or both of an inlet of the first tube and an intermediate portion between the tube sections to intermingle with and oxidize the entrained gases evolved from the sample. Oxidation of those gases is completed in the catalyst in each second tube section. A thermocouple within a sample reduces furnace temperature when an exothermic condition is sensed within the sample. Oxidized gases flow from outlets of the tubes to individual gas cells. The cells are sequentially aligned with an infrared detector, which senses the composition and quantities of the gas components. Each elongated cell is tapered inward toward the center from cell windows at the ends. Volume is reduced from a conventional cell, while permitting maximum interaction of gas with the light beam. Reduced volume and angulation of the cell inlets provide rapid purgings of the cell, providing shorter cycles between detections. For coal and other high molecular weight samples, from 50% to 100% oxygen is introduced to the tubes.

  7. Canopy temperature depression sampling to assess grain yield and genotypic differentiation in winter wheat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Canopy temperature depression (CTD = Ta - Tc) has been used to model crop yield, heat, and drought tolerance; but when to measure CTD for breeding selection has seldom been addressed. Our objective was to determine optimal measurement times in relation to growth stage, time of day, and environment. ...

  8. A Nonlinear Viscoelastic Model for Ceramics at High Temperatures

    NASA Technical Reports Server (NTRS)

    Powers, Lynn M.; Panoskaltsis, Vassilis P.; Gasparini, Dario A.; Choi, Sung R.

    2002-01-01

    High-temperature creep behavior of ceramics is characterized by nonlinear time-dependent responses, asymmetric behavior in tension and compression, and nucleation and coalescence of voids leading to creep rupture. Moreover, creep rupture experiments show considerable scatter or randomness in fatigue lives of nominally equal specimens. To capture the nonlinear, asymmetric time-dependent behavior, the standard linear viscoelastic solid model is modified. Nonlinearity and asymmetry are introduced in the volumetric components by using a nonlinear function similar to a hyperbolic sine function but modified to model asymmetry. The nonlinear viscoelastic model is implemented in an ABAQUS user material subroutine. To model the random formation and coalescence of voids, each element is assigned a failure strain sampled from a lognormal distribution. An element is deleted when its volumetric strain exceeds its failure strain. Element deletion has been implemented within ABAQUS. Temporal increases in strains produce a sequential loss of elements (a model for void nucleation and growth), which in turn leads to failure. Nonlinear viscoelastic model parameters are determined from uniaxial tensile and compressive creep experiments on silicon nitride. The model is then used to predict the deformation of four-point bending and ball-on-ring specimens. Simulation is used to predict statistical moments of creep rupture lives. Numerical simulation results compare well with results of experiments of four-point bending specimens. The analytical model is intended to be used to predict the creep rupture lives of ceramic parts in arbitrary stress conditions.

  9. Modeling 3D faces from samplings via compressive sensing

    NASA Astrophysics Data System (ADS)

    Sun, Qi; Tang, Yanlong; Hu, Ping

    2013-07-01

    3D data is easier to acquire for family entertainment purpose today because of the mass-production, cheapness and portability of domestic RGBD sensors, e.g., Microsoft Kinect. However, the accuracy of facial modeling is affected by the roughness and instability of the raw input data from such sensors. To overcome this problem, we introduce compressive sensing (CS) method to build a novel 3D super-resolution scheme to reconstruct high-resolution facial models from rough samples captured by Kinect. Unlike the simple frame fusion super-resolution method, this approach aims to acquire compressed samples for storage before a high-resolution image is produced. In this scheme, depth frames are firstly captured and then each of them is measured into compressed samples using sparse coding. Next, the samples are fused to produce an optimal one and finally a high-resolution image is recovered from the fused sample. This framework is able to recover 3D facial model of a given user from compressed simples and this can reducing storage space as well as measurement cost in future devices e.g., single-pixel depth cameras. Hence, this work can potentially be applied into future applications, such as access control system using face recognition, and smart phones with depth cameras, which need high resolution and little measure time.

  10. Modeling Background Attenuation by Sample Matrix in Gamma Spectrometric Analyses

    SciTech Connect

    Bastos, Rodrigo O.; Appoloni, Carlos R.

    2008-08-07

    In laboratory gamma spectrometric analyses, the procedures for estimating background usually overestimate it. If an empty container similar to that used to hold samples is measured, it does not consider the background attenuation by sample matrix. If a 'blank' sample is measured, the hypothesis that this sample will be free of radionuclides is generally not true. The activity of this 'blank' sample is frequently sufficient to mask or to overwhelm the effect of attenuation so that the background remains overestimated. In order to overcome this problem, a model was developed to obtain the attenuated background from the spectrum acquired with the empty container. Beyond reasonable hypotheses, the model presumes the knowledge of the linear attenuation coefficient of the samples and its dependence on photon energy and samples densities. An evaluation of the effects of this model on the Lowest Limit of Detection (LLD) is presented for geological samples placed in cylindrical containers that completely cover the top of an HPGe detector that has a 66% relative efficiency. The results are presented for energies in the range of 63 to 2614keV, for sample densities varying from 1.5 to 2.5 g{center_dot}cm{sup -3}, and for the height of the material on the detector of 2 cm and 5 cm. For a sample density of 2.0 g{center_dot}cm{sup -3} and with a 2cm height, the method allowed for a lowering of 3.4% of the LLD for the energy of 1460keV, from {sup 40}K, 3.9% for the energy of 911keV from {sup 228}Ac, 4.5% for the energy of 609keV from {sup 214}Bi, and8.3% for the energy of 92keV from {sup 234}Th. For a sample density of 1.75 g{center_dot}cm{sup -3} and a 5cm height, the method indicates a lowering of 6.5%, 7.4%, 8.3% and 12.9% of the LLD for the same respective energies.

  11. Long-term room temperature preservation of corpse soft tissue: an approach for tissue sample storage

    PubMed Central

    2011-01-01

    Background Disaster victim identification (DVI) represents one of the most difficult challenges in forensic sciences, and subsequent DNA typing is essential. Collected samples for DNA-based human identification are usually stored at low temperature to halt the degradation processes of human remains. We have developed a simple and reliable procedure for soft tissue storage and preservation for DNA extraction. It ensures high quality DNA suitable for PCR-based DNA typing after at least 1 year of room temperature storage. Methods Fragments of human psoas muscle were exposed to three different environmental conditions for diverse time periods at room temperature. Storage conditions included: (a) a preserving medium consisting of solid sodium chloride (salt), (b) no additional substances and (c) garden soil. DNA was extracted with proteinase K/SDS followed by organic solvent treatment and concentration by centrifugal filter devices. Quantification was carried out by real-time PCR using commercial kits. Short tandem repeat (STR) typing profiles were analysed with 'expert software'. Results DNA quantities recovered from samples stored in salt were similar up to the complete storage time and underscored the effectiveness of the preservation method. It was possible to reliably and accurately type different genetic systems including autosomal STRs and mitochondrial and Y-chromosome haplogroups. Autosomal STR typing quality was evaluated by expert software, denoting high quality profiles from DNA samples obtained from corpse tissue stored in salt for up to 365 days. Conclusions The procedure proposed herein is a cost efficient alternative for storage of human remains in challenging environmental areas, such as mass disaster locations, mass graves and exhumations. This technique should be considered as an additional method for sample storage when preservation of DNA integrity is required for PCR-based DNA typing. PMID:21846338

  12. Accelerated failure time model under general biased sampling scheme.

    PubMed

    Kim, Jane Paik; Sit, Tony; Ying, Zhiliang

    2016-07-01

    Right-censored time-to-event data are sometimes observed from a (sub)cohort of patients whose survival times can be subject to outcome-dependent sampling schemes. In this paper, we propose a unified estimation method for semiparametric accelerated failure time models under general biased estimating schemes. The proposed estimator of the regression covariates is developed upon a bias-offsetting weighting scheme and is proved to be consistent and asymptotically normally distributed. Large sample properties for the estimator are also derived. Using rank-based monotone estimating functions for the regression parameters, we find that the estimating equations can be easily solved via convex optimization. The methods are confirmed through simulations and illustrated by application to real datasets on various sampling schemes including length-bias sampling, the case-cohort design and its variants. PMID:26941240

  13. Language Arts Curriculum Framework: Sample Curriculum Model, Grade 1.

    ERIC Educational Resources Information Center

    Arkansas State Dept. of Education, Little Rock.

    Based on the 1998 Arkansas State Language Arts Framework, this sample curriculum model for grade one language arts is divided into sections focusing on writing; listening, speaking, and viewing; and reading. Each section lists standards; benchmarks; assessments; and strategies/activities. The reading section itself is divided into print awareness;…

  14. Language Arts Curriculum Framework: Sample Curriculum Model, Grade K.

    ERIC Educational Resources Information Center

    Arkansas State Dept. of Education, Little Rock.

    Based on the 1998 Arkansas State Language Arts Framework, this sample curriculum model for kindergarten language arts is divided into sections focusing on writing; listening, speaking, and viewing; and reading. Each section lists standards; benchmarks; assessments; and strategies/activities. The reading section itself is divided into print…

  15. A three stage sampling model for remote sensing applications

    NASA Technical Reports Server (NTRS)

    Eisgruber, L. M.

    1972-01-01

    A conceptual model and an empirical application of the relationship between the manner of selecting observations and its effect on the precision of estimates from remote sensing are reported. This three stage sampling scheme considers flightlines, segments within flightlines, and units within these segments. The error of estimate is dependent on the number of observations in each of the stages.

  16. Automated biowaste sampling system urine subsystem operating model, part 1

    NASA Technical Reports Server (NTRS)

    Fogal, G. L.; Mangialardi, J. K.; Rosen, F.

    1973-01-01

    The urine subsystem automatically provides for the collection, volume sensing, and sampling of urine from six subjects during space flight. Verification of the subsystem design was a primary objective of the current effort which was accomplished thru the detail design, fabrication, and verification testing of an operating model of the subsystem.

  17. NERVE AS MODEL TEMPERATURE END ORGAN

    PubMed Central

    Bernhard, C. G.; Granit, Ragnar

    1946-01-01

    Rapid local cooling of mammalian nerve sets up a discharge which is preceded by a local temperature potential, the cooled region being electronegative relative to a normal portion of the nerve. Heating the nerve locally above its normal temperature similarly makes the heated region electronegative relative to a region at normal temperature, and again a discharge is set up from the heated region. These local temperature potentials, set up by the nerve itself, are held to serve as "generator potentials" and the mechanism found is regarded as the prototype for temperature end organs. PMID:19873460

  18. Water adsorption at high temperature on core samples from The Geysers geothermal field

    SciTech Connect

    Gruszkiewicz, M.S.; Horita, J.; Simonson, J.M.; Mesmer, R.E.

    1998-06-01

    The quantity of water retained by rock samples taken from three wells located in The Geysers geothermal field, California, was measured at 150, 200, and 250 C as a function of steam pressure in the range 0.00 {le} p/p{sub 0} {le} 0.98, where p{sub 0} is the saturated water vapor pressure. Both adsorption and desorption runs were made in order to investigate the extent of the hysteresis. Additionally, low temperature gas adsorption analyses were made on the same rock samples. Mercury intrusion porosimetry was also used to obtain similar information extending to very large pores (macropores). A qualitative correlation was found between the surface properties obtained from nitrogen adsorption and the mineralogical and petrological characteristics of the solids. However, there was no direct correlation between BET specific surface areas and the capacity of the rocks for water adsorption at high temperatures. The hysteresis decreased significantly at 250 C. The results indicate that multilayer adsorption, rather than capillary condensation, is the dominant water storage mechanism at high temperatures.

  19. Water adsorption at high temperature on core samples from The Geysers geothermal field

    SciTech Connect

    Gruszkiewicz, M.S.; Horita, J.; Simonson, J.M.; Mesmer, R.E.

    1998-06-01

    The quantity of water retained by rock samples taken from three wells located in The Geysers geothermal reservoir, California, was measured at 150, 200, and 250 C as a function of pressure in the range 0.00 {le} p/p{sub 0} {le} 0.98, where p{sub 0} is the saturated water vapor pressure. Both adsorption (increasing pressure) and desorption (decreasing pressure) runs were made in order to investigate the nature and the extent of the hysteresis. Additionally, low temperature gas adsorption analyses were performed on the same rock samples. Nitrogen or krypton adsorption and desorption isotherms at 77 K were used to obtain BET specific surface areas, pore volumes and their distributions with respect to pore sizes. Mercury intrusion porosimetry was also used to obtain similar information extending to very large pores (macropores). A qualitative correlation was found between the surface properties obtained from nitrogen adsorption and the mineralogical and petrological characteristics of the solids. However, there is in general no proportionality between BET specific surface areas and the capacity of the rocks for water adsorption at high temperatures. The results indicate that multilayer adsorption rather than capillary condensation is the dominant water storage mechanism at high temperatures.

  20. A temperature dependent SPICE macro-model for power MOSFETs

    SciTech Connect

    Pierce, D.G.

    1991-01-01

    The power MOSFET SPICE Macro-Model has been developed suitable for use over the temperature range {minus}55 to 125 {degrees}C. The model is comprised of a single parameter set with temperature dependence accessed through the SPICE .TEMP card. SPICE parameter extraction techniques for the model and model predictive accuracy are discussed. 7 refs., 8 figs., 1 tab.

  1. Data augmentation for models based on rejection sampling

    PubMed Central

    Rao, Vinayak; Lin, Lizhen; Dunson, David B.

    2016-01-01

    We present a data augmentation scheme to perform Markov chain Monte Carlo inference for models where data generation involves a rejection sampling algorithm. Our idea is a simple scheme to instantiate the rejected proposals preceding each data point. The resulting joint probability over observed and rejected variables can be much simpler than the marginal distribution over the observed variables, which often involves intractable integrals. We consider three problems: modelling flow-cytometry measurements subject to truncation; the Bayesian analysis of the matrix Langevin distribution on the Stiefel manifold; and Bayesian inference for a nonparametric Gaussian process density model. The latter two are instances of doubly-intractable Markov chain Monte Carlo problems, where evaluating the likelihood is intractable. Our experiments demonstrate superior performance over state-of-the-art sampling algorithms for such problems. PMID:27279660

  2. Simulating canopy temperature for modelling heat stress in cereals

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Crop models must be improved to account for the large effects of heat stress effects on crop yields. To date, most approaches in crop models use air temperature despite evidence that crop canopy temperature better explains yield reductions associated with high temperature events. This study presents...

  3. Decision Models for Determining the Optimal Life Test Sampling Plans

    NASA Astrophysics Data System (ADS)

    Nechval, Nicholas A.; Nechval, Konstantin N.; Purgailis, Maris; Berzins, Gundars; Strelchonok, Vladimir F.

    2010-11-01

    Life test sampling plan is a technique, which consists of sampling, inspection, and decision making in determining the acceptance or rejection of a batch of products by experiments for examining the continuous usage time of the products. In life testing studies, the lifetime is usually assumed to be distributed as either a one-parameter exponential distribution, or a two-parameter Weibull distribution with the assumption that the shape parameter is known. Such oversimplified assumptions can facilitate the follow-up analyses, but may overlook the fact that the lifetime distribution can significantly affect the estimation of the failure rate of a product. Moreover, sampling costs, inspection costs, warranty costs, and rejection costs are all essential, and ought to be considered in choosing an appropriate sampling plan. The choice of an appropriate life test sampling plan is a crucial decision problem because a good plan not only can help producers save testing time, and reduce testing cost; but it also can positively affect the image of the product, and thus attract more consumers to buy it. This paper develops the frequentist (non-Bayesian) decision models for determining the optimal life test sampling plans with an aim of cost minimization by identifying the appropriate number of product failures in a sample that should be used as a threshold in judging the rejection of a batch. The two-parameter exponential and Weibull distributions with two unknown parameters are assumed to be appropriate for modelling the lifetime of a product. A practical numerical application is employed to demonstrate the proposed approach.

  4. Modeling of temperature sensor built on GaN nanostructures

    NASA Astrophysics Data System (ADS)

    Asgari, A.; Taheri, S.

    2011-03-01

    A GaN nanostructure based temperature sensor has been modeled using the minority-carrier exclusion theory. The model takes into account the effects of temperature, carrier concentrations and electric field on carrier mobilities. The model also consists of different carrier scattering mechanisms such as phonon and natural ionized scattering. The calculation results show that the resistance of modeled GaN nanostructure based temperature sensor is strongly dependent on the sensor structural parameters such as doping density and device size.

  5. Ellipsoidal nested sampling, expression of the model uncertainty and measurement

    NASA Astrophysics Data System (ADS)

    Palmisano, C.; Mana, G.; Gervino, G.

    2015-07-01

    The measurand value, the conclusions, and the decisions inferred from measurements may depend on the models used to explain and to analyze the results. In this paper, the problems of identifying the most appropriate model and of assessing the model contribution to the uncertainty are formulated and solved in terms of Bayesian model selection and model averaging. As computational cost of this approach increases with the dimensionality of the problem, a numerical strategy, based on multimodal ellipsoidal nested sampling, to integrate over the nuisance parameters and to compute the measurand post-data distribution is outlined. In order to illustrate the numerical strategy, by use of MATHEMATICA an elementary example concerning a bimodal, two-dimensional distribution has also been studied.

  6. Study of Low Temperature Baking Effect on Field Emission on Nb Samples Treated by BEP, EP, and BCP

    SciTech Connect

    Andy Wu, Song Jin, Robert Rimmer, Xiang Yang Lu, K. Zhao, Laura MacIntyre, Robert Ike

    2010-05-01

    Field emission is still one of the major obstacles facing Nb superconducting radio frequency (SRF) community for allowing Nb SRF cavities to reach routinely accelerating gradient of 35 MV/m that is required for the international linear collider. Nowadays, the well know low temperature backing at 120 oC for 48 hours is a common procedure used in the SRF community to improve the high field Q slope. However, some cavity production data have showed that the low temperature baking may induce field emission for cavities treated by EP. On the other hand, an earlier study of field emission on Nb flat samples treated by BCP showed an opposite conclusion. In this presentation, the preliminary measurements of Nb flat samples treated by BEP, EP, and BCP via our unique home-made scanning field emission microscope before and after the low temperature baking are reported. Some correlations between surface smoothness and the number of the observed field emitters were found. The observed experimental results can be understood, at least partially, by a simple model that involves the change of the thickness of the pent-oxide layer on Nb surfaces.

  7. Temperature distributions in the laser-heated diamond anvil cell from 3-D numerical modeling

    SciTech Connect

    Rainey, E. S. G.; Kavner, A.; Hernlund, J. W.

    2013-11-28

    We present TempDAC, a 3-D numerical model for calculating the steady-state temperature distribution for continuous wave laser-heated experiments in the diamond anvil cell. TempDAC solves the steady heat conduction equation in three dimensions over the sample chamber, gasket, and diamond anvils and includes material-, temperature-, and direction-dependent thermal conductivity, while allowing for flexible sample geometries, laser beam intensity profile, and laser absorption properties. The model has been validated against an axisymmetric analytic solution for the temperature distribution within a laser-heated sample. Example calculations illustrate the importance of considering heat flow in three dimensions for the laser-heated diamond anvil cell. In particular, we show that a “flat top” input laser beam profile does not lead to a more uniform temperature distribution or flatter temperature gradients than a wide Gaussian laser beam.

  8. Sampling and specimens: potential application of a general model in geoscience sample registration

    NASA Astrophysics Data System (ADS)

    Cox, S. J.; Habermann, T.; Duclaux, G.

    2011-12-01

    Sampling is a key element of observational science. Specimens are a particular class of sample, in which material is retrieved from its original location and used for ex-situ observations and analysis. Specimens retrieved from difficult locations (e.g. deep ocean sampling, extra-terrestrial sampling) or of rare phenomena, have special scientific value. Material from these may be distributed to multiple laboratories for observation. For maximum utility, reports from the different studies must be recognized and compared. This has been a challenge as the original specimens are often not clearly identified or existing ids are not reported. To mitigate this, the International Geologic Specimen Number (IGSN) provides universal, project-neutral identifiers for geoscience specimens, and SESAR a system for registering those identifiers. Standard descriptive information required for specimen registration was proposed during a SESAR meeting held in February 2011. The standard ISO 19156 'Observations and Measurements' (O&M) includes an information model for basic description of specimens. The specimen model was designed to accommodate a variety of scenarios in chemistry, geochemistry, field geology, and life-sciences, and is believed to be applicable to a wide variety of application domains. O&M is implemented in XML (as a GML Schema) for OGC services and we have recently developed a complementary semantic-web compatible RDF/OWL representation. The GML form is used in several services deployed through AuScope, and for water quality information in WIRADA. The model has underpinned the redevelopment of a large geochemistry database in CSIRO. Capturing the preparation chain is the particular challenge in (geo-) chemistry, so the flexible and scalable model provided by the specimen model in O&M has been critical to its success in this context. This standard model for specimen metadata appears to satisfy all SESAR requirements, so might serve as the basic schema in the SESAR

  9. Far-infrared Dust Temperatures and Column Densities of the MALT90 Molecular Clump Sample

    NASA Astrophysics Data System (ADS)

    Guzmán, Andrés E.; Sanhueza, Patricio; Contreras, Yanett; Smith, Howard A.; Jackson, James M.; Hoq, Sadia; Rathborne, Jill M.

    2015-12-01

    We present dust column densities and dust temperatures for ˜3000 young, high-mass molecular clumps from the Millimeter Astronomy Legacy Team 90 GHz survey, derived from adjusting single-temperature dust emission models to the far-infrared intensity maps measured between 160 and 870 μm from the Herschel/Herschel Infrared Galactic Plane Survey (Hi-Gal) and APEX/APEX Telescope Large Area Survey of the Galaxy (ATLASGAL) surveys. We discuss the methodology employed in analyzing the data, calculating physical parameters, and estimating their uncertainties. The population average dust temperature of the clumps are 16.8 ± 0.2 K for the clumps that do not exhibit mid-infrared signatures of star formation (quiescent clumps), 18.6 ± 0.2 K for the clumps that display mid-infrared signatures of ongoing star formation but have not yet developed an H ii region (protostellar clumps), and 23.7 ± 0.2 and 28.1 ± 0.3 K for clumps associated with H ii and photo-dissociation regions, respectively. These four groups exhibit large overlaps in their temperature distributions, with dispersions ranging between 4 and 6 K. The median of the peak column densities of the protostellar clump population is 0.20 ± 0.02 g cm-2, which is about 50% higher compared to the median of the peak column densities associated with clumps in the other evolutionary stages. We compare the dust temperatures and column densities measured toward the center of the clumps with the mean values of each clump. We find that in the quiescent clumps, the dust temperature increases toward the outer regions and that these clumps are associated with the shallowest column density profiles. In contrast, molecular clumps in the protostellar or H ii region phase have dust temperature gradients more consistent with internal heating and are associated with steeper column density profiles compared with the quiescent clumps.

  10. Optimizing the implementation of the target motion sampling temperature treatment technique - How fast can it get?

    SciTech Connect

    Tuomas, V.; Jaakko, L.

    2013-07-01

    This article discusses the optimization of the target motion sampling (TMS) temperature treatment method, previously implemented in the Monte Carlo reactor physics code Serpent 2. The TMS method was introduced in [1] and first practical results were presented at the PHYSOR 2012 conference [2]. The method is a stochastic method for taking the effect of thermal motion into account on-the-fly in a Monte Carlo neutron transport calculation. It is based on sampling the target velocities at collision sites and then utilizing the 0 K cross sections at target-at-rest frame for reaction sampling. The fact that the total cross section becomes a distributed quantity is handled using rejection sampling techniques. The original implementation of the TMS requires 2.0 times more CPU time in a PWR pin-cell case than a conventional Monte Carlo calculation relying on pre-broadened effective cross sections. In a HTGR case examined in this paper the overhead factor is as high as 3.6. By first changing from a multi-group to a continuous-energy implementation and then fine-tuning a parameter affecting the conservativity of the majorant cross section, it is possible to decrease the overhead factors to 1.4 and 2.3, respectively. Preliminary calculations are also made using a new and yet incomplete optimization method in which the temperature of the basis cross section is increased above 0 K. It seems that with the new approach it may be possible to decrease the factors even as low as 1.06 and 1.33, respectively, but its functionality has not yet been proven. Therefore, these performance measures should be considered preliminary. (authors)

  11. Learning Adaptive Forecasting Models from Irregularly Sampled Multivariate Clinical Data

    PubMed Central

    Liu, Zitao; Hauskrecht, Milos

    2016-01-01

    Building accurate predictive models of clinical multivariate time series is crucial for understanding of the patient condition, the dynamics of a disease, and clinical decision making. A challenging aspect of this process is that the model should be flexible and adaptive to reflect well patient-specific temporal behaviors and this also in the case when the available patient-specific data are sparse and short span. To address this problem we propose and develop an adaptive two-stage forecasting approach for modeling multivariate, irregularly sampled clinical time series of varying lengths. The proposed model (1) learns the population trend from a collection of time series for past patients; (2) captures individual-specific short-term multivariate variability; and (3) adapts by automatically adjusting its predictions based on new observations. The proposed forecasting model is evaluated on a real-world clinical time series dataset. The results demonstrate the benefits of our approach on the prediction tasks for multivariate, irregularly sampled clinical time series, and show that it can outperform both the population based and patient-specific time series prediction models in terms of prediction accuracy. PMID:27525189

  12. The Genealogy of Samples in Models with Selection

    PubMed Central

    Neuhauser, C.; Krone, S. M.

    1997-01-01

    We introduce the genealogy of a random sample of genes taken from a large haploid population that evolves according to random reproduction with selection and mutation. Without selection, the genealogy is described by Kingman's well-known coalescent process. In the selective case, the genealogy of the sample is embedded in a graph with a coalescing and branching structure. We describe this graph, called the ancestral selection graph, and point out differences and similarities with Kingman's coalescent. We present simulations for a two-allele model with symmetric mutation in which one of the alleles has a selective advantage over the other. We find that when the allele frequencies in the population are already in equilibrium, then the genealogy does not differ much from the neutral case. This is supported by rigorous results. Furthermore, we describe the ancestral selection graph for other selective models with finitely many selection classes, such as the K-allele models, infinitely-many-alleles models, DNA sequence models, and infinitely-many-sites models, and briefly discuss the diploid case. PMID:9071604

  13. Modeling the Freezing of SN in High Temperature Furnaces

    NASA Technical Reports Server (NTRS)

    Brush, Lucien

    1999-01-01

    Presently, crystal growth furnaces are being designed that will be used to monitor the crystal melt interface shape and the solutal and thermal fields in its vicinity during the directional freezing of dilute binary alloys, To monitor the thermal field within the solidifying materials, thermocouple arrays (AMITA) are inserted into the sample. Intrusive thermocouple monitoring devices can affect the experimental data being measured. Therefore, one objective of this work is to minimize the effect of the thermocouples on the data generated. To aid in accomplishing this objective, two models of solidification have been developed. Model A is a fully transient, one dimensional model for the freezing of a dilute binary alloy that is used to compute temperature profiles for comparison with measurements taken from the thermocouples. Model B is a fully transient two dimensional model of the solidification of a pure metal. It will be used to uncover the manner in which thermocouple placement and orientation within the ampoule breaks the longitudinal axis of symmetry of the thermal field and the crystal-melt interface. Results and conclusions are based on the comparison of the models with experimental results taken during the freezing of pure Sn.

  14. Exposure Of NIF Relevant Polymeric Samples To Deuterium-Tritium Gas At Elevated Temperature And Pressure

    SciTech Connect

    Ebey, P S; Dole, J M; Nobile, A; Schoonover, J R; Burmann, J; Cook, B; Letts, S; Sanchez, J; Nikroo, A

    2005-06-24

    The purpose of the experiments described in this paper was to expose samples of polymeric materials to a mixture of deuterium-tritium (DT) gas at elevated temperature and pressure to investigate the effects (i.e. damage) on the materials. The materials and exposure parameters were chosen with to be relevant to proposed uses of similar materials in inertial fusion ignition experiments at the National Ignition Facility. Two types of samples were exposed and tested. The first type consisted of 10 4-lead ribbon cables of fine manganin wire insulated with polyimide. Wires of this type are proposed for use in thermal shimming of hohlraums and the goal of this experiment was to measure the change in electrical resistance of the insulation due to tritium exposure. The second type of sample consisted of 20 planar polymer samples that may be used as ignition capsule materials. The exposure was at 34.5 GPa (5010 psia) and 70 C for 48 hours. The change in electrical resistance of the wire insulation will be presented. The results for capsule materials will be presented in a separate paper in this issue.

  15. Model Based Unsupervised Learning Guided by Abundant Background Samples

    PubMed Central

    Mahdi, Rami N.; Rouchka, Eric C.

    2010-01-01

    Many data sets contain an abundance of background data or samples belonging to classes not currently under consideration. We present a new unsupervised learning method based on Fuzzy C-Means to learn sub models of a class using background samples to guide cluster split and merge operations. The proposed method demonstrates how background samples can be used to guide and improve the clustering process. The proposed method results in more accurate clusters and helps to escape locally minimum solutions. In addition, the number of clusters is determined for the class under consideration. The method demonstrates remarkable performance on both synthetic 2D and real world data from the MNIST dataset of hand written digits. PMID:20436793

  16. Automation of sample plan creation for process model calibration

    NASA Astrophysics Data System (ADS)

    Oberschmidt, James; Abdo, Amr; Desouky, Tamer; Al-Imam, Mohamed; Krasnoperova, Azalia; Viswanathan, Ramya

    2010-04-01

    The process of preparing a sample plan for optical and resist model calibration has always been tedious. Not only because it is required to accurately represent full chip designs with countless combinations of widths, spaces and environments, but also because of the constraints imposed by metrology which may result in limiting the number of structures to be measured. Also, there are other limits on the types of these structures, and this is mainly due to the accuracy variation across different types of geometries. For instance, pitch measurements are normally more accurate than corner rounding. Thus, only certain geometrical shapes are mostly considered to create a sample plan. In addition, the time factor is becoming very crucial as we migrate from a technology node to another due to the increase in the number of development and production nodes, and the process is getting more complicated if process window aware models are to be developed in a reasonable time frame, thus there is a need for reliable methods to choose sample plans which also help reduce cycle time. In this context, an automated flow is proposed for sample plan creation. Once the illumination and film stack are defined, all the errors in the input data are fixed and sites are centered. Then, bad sites are excluded. Afterwards, the clean data are reduced based on geometrical resemblance. Also, an editable database of measurement-reliable and critical structures are provided, and their percentage in the final sample plan as well as the total number of 1D/2D samples can be predefined. It has the advantage of eliminating manual selection or filtering techniques, and it provides powerful tools for customizing the final plan, and the time needed to generate these plans is greatly reduced.

  17. Sample temperature profile during the excimer laser annealing of silicon nanoparticles

    NASA Astrophysics Data System (ADS)

    Caninenberg, M.; Verheyen, E.; Kiesler, D.; Stoib, B.; Brandt, M. S.; Benson, N.; Schmechel, R.

    2015-11-01

    Based on the heat diffusion equation we describe the temperature profile of a silicon nanoparticle thin film on silicon during excimer laser annealing using COMSOL Multiphysics. For this purpose system specific material parameters are determined such as the silicon nanoparticle melting point at 1683 K, the surface reflectivity at 248 nm of 20% and the nanoparticle thermal conductivity between 0.3 and 1.2 W/m K. To validate our model, the simulation results are compared to experimental data obtained by Raman spectroscopy, SEM microscopy and electrochemical capacitance-voltage measurements (ECV). The experimental data are in good agreement with our theoretical findings and support the validity of the model.

  18. Imputation for semiparametric transformation models with biased-sampling data

    PubMed Central

    Liu, Hao; Qin, Jing; Shen, Yu

    2012-01-01

    Widely recognized in many fields including economics, engineering, epidemiology, health sciences, technology and wildlife management, length-biased sampling generates biased and right-censored data but often provide the best information available for statistical inference. Different from traditional right-censored data, length-biased data have unique aspects resulting from their sampling procedures. We exploit these unique aspects and propose a general imputation-based estimation method for analyzing length-biased data under a class of flexible semiparametric transformation models. We present new computational algorithms that can jointly estimate the regression coefficients and the baseline function semiparametrically. The imputation-based method under the transformation model provides an unbiased estimator regardless whether the censoring is independent or not on the covariates. We establish large-sample properties using the empirical processes method. Simulation studies show that under small to moderate sample sizes, the proposed procedure has smaller mean square errors than two existing estimation procedures. Finally, we demonstrate the estimation procedure by a real data example. PMID:22903245

  19. Temperature and electron density distributions of laser-induced plasmas generated with an iron sample at different ambient gas pressures

    NASA Astrophysics Data System (ADS)

    Aguilera, J. A.; Aragón, C.

    2002-09-01

    Intensity, temperature and electron density distributions of laser-induced plasmas (LIPs) have been measured by emission spectroscopy with two-dimensional spatial resolution and temporal resolution. The plasmas have been generated with an iron sample at different pressures of air, in the range 10-1000 mbar. An experimental system based in an imaging spectrometer equipped with an intensified CCD detector has been used to obtain the spectra with two-dimensional spatial resolution. The evolution of the intensity distributions is described by the blast wave model only at initial times. The temperature distributions are shown to correspond to a slight difference between the intensity distributions of two Fe I emission lines that have a high difference of their upper energy levels (3.38 eV). The electron density distributions have similar features to those of the temperature distributions. The features of the intensity and temperature distributions show a significant change with the ambient gas pressure: they have separated maxima in the plasmas generated at pressures below 100 mbar, whereas at higher pressures, the maxima of the two distributions coincide.

  20. NASTRAN thermal analyzer: Theory and application including a guide to modeling engineering problems, volume 2. [sample problem library guide

    NASA Technical Reports Server (NTRS)

    Jackson, C. E., Jr.

    1977-01-01

    A sample problem library containing 20 problems covering most facets of Nastran Thermal Analyzer modeling is presented. Areas discussed include radiative interchange, arbitrary nonlinear loads, transient temperature and steady-state structural plots, temperature-dependent conductivities, simulated multi-layer insulation, and constraint techniques. The use of the major control options and important DMAP alters is demonstrated.

  1. Simple determination of the herbicide napropamide in water and soil samples by room temperature phosphorescence.

    PubMed

    Salinas-Castillo, Alfonso; Fernández-Sanchez, Jorge Fernando; Segura-Carretero, Antonio; Fernández-Gutiérrez, Alberto

    2005-08-01

    A new, simple, rapid and selective phosphorimetric method for determining napropamide is proposed which demonstrates the applicability of heavy-atom-induced room-temperature phosphorescence for analyzing pesticides in real samples. The phosphorescence signals are a consequence of intermolecular protection and are found exclusively with analytes in the presence of heavy atom salts. Sodium sulfite was used as an oxygen scavenger to minimize room-temperature phosphorescence quenching. The determination was performed in 1 M potassium iodide and 6 mM sodium sulfite at 20 degrees C. The phosphorescence intensity was measured at 520 nm with excitation at 290 nm. Phosphorescence was easily developed, with a linear relation to concentration between 3.2 and 600.0 ng ml(-1) and a detection limit of 3.2 ng ml(-1). The method has been successfully applied to the analysis of napropamide in water and soil samples and an exhaustive interference study was also carried out to display the selectivity of the proposed method. PMID:15838936

  2. Ambient temperature modelling with soft computing techniques

    SciTech Connect

    Bertini, Ilaria; Ceravolo, Francesco; Citterio, Marco; Di Pietra, Biagio; Margiotta, Francesca; Pizzuti, Stefano; Puglisi, Giovanni; De Felice, Matteo

    2010-07-15

    This paper proposes a hybrid approach based on soft computing techniques in order to estimate monthly and daily ambient temperature. Indeed, we combine the back-propagation (BP) algorithm and the simple Genetic Algorithm (GA) in order to effectively train artificial neural networks (ANN) in such a way that the BP algorithm initialises a few individuals of the GA's population. Experiments concerned monthly temperature estimation of unknown places and daily temperature estimation for thermal load computation. Results have shown remarkable improvements in accuracy compared to traditional methods. (author)

  3. Physical Models of Seismic-Attenuation Measurements on Lab Samples

    NASA Astrophysics Data System (ADS)

    Coulman, T. J.; Morozov, I. B.

    2012-12-01

    Seismic attenuation in Earth materials is often measured in the lab by using low-frequency forced oscillations or static creep experiments. The usual assumption in interpreting and even designing such experiments is the "viscoelastic" behavior of materials, i.e., their description by the notions of a Q-factor and material memory. However, this is not the only theoretical approach to internal friction, and it also involves several contradictions with conventional mechanics. From the viewpoint of mechanics, the frequency-dependent Q becomes a particularly enigmatic property attributed to the material. At the same time, the behavior of rock samples in seismic-attenuation experiments can be explained by a strictly mechanical approach. We use this approach to simulate such experiments analytically and numerically for a system of two cylinders consisting of a rock sample and elastic standard undergoing forced oscillations, and also for a single rock sample cylinder undergoing static creep. The system is subject to oscillatory compression or torsion, and the phase-lag between the sample and standard is measured. Unlike in the viscoelastic approach, a full Lagrangian formulation is considered, in which material anelasticity is described by parameters of "solid viscosity" and a dissipation function from which the constitutive equation is derived. Results show that this physical model of anelasticity predicts creep results very close to those obtained by using empirical Burger's bodies or Andrade laws. With nonlinear (non-Newtonian) solid viscosity, the system shows an almost instantaneous initial deformation followed by slow creep towards an equilibrium. For Aheim Dunite, the "rheologic" parameters of nonlinear viscosity are υ=0.79 and η=2.4 GPa-s. Phase-lag results for nonlinear viscosity show Q's slowly decreasing with frequency. To explain a Q increasing with frequency (which is often observed in the lab and in the field), one has to consider nonlinear viscosity with

  4. A NEW SAMPLE CELL DESIGN FOR STUDYING SOLID-MATRIX ROOM TEMPERATURE PHOSPHORESCENCE MOISTURE QUENCHING. (R824100)

    EPA Science Inventory

    A new sample chamber was developed that can be used in the measurement of the effects of moisture on the room-temperature solid-matrix phosphorescence of phosphors adsorbed onto filter paper. The sample chamber consists of a sealed quartz cell that contains a special teflon sampl...

  5. Field portable low temperature porous layer open tubular cryoadsorption headspace sampling and analysis part II: Applications.

    PubMed

    Harries, Megan; Bukovsky-Reyes, Santiago; Bruno, Thomas J

    2016-01-15

    This paper details the sampling methods used with the field portable porous layer open tubular cryoadsorption (PLOT-cryo) approach, described in Part I of this two-part series, applied to several analytes of interest. We conducted tests with coumarin and 2,4,6-trinitrotoluene (two solutes that were used in initial development of PLOT-cryo technology), naphthalene, aviation turbine kerosene, and diesel fuel, on a variety of matrices and test beds. We demonstrated that these analytes can be easily detected and reliably identified using the portable unit for analyte collection. By leveraging efficiency-boosting temperature control and the high flow rate multiple capillary wafer, very short collection times (as low as 3s) yielded accurate detection. For diesel fuel spiked on glass beads, we determined a method detection limit below 1 ppm. We observed greater variability among separate samples analyzed with the portable unit than previously documented in work using the laboratory-based PLOT-cryo technology. We identify three likely sources that may help explain the additional variation: the use of a compressed air source to generate suction, matrix geometry, and variability in the local vapor concentration around the sampling probe as solute depletion occurs both locally around the probe and in the test bed as a whole. This field-portable adaptation of the PLOT-cryo approach has numerous and diverse potential applications. PMID:26726934

  6. Two-Temperature Model of Nonequilibrium Electron Relaxation:. a Review

    NASA Astrophysics Data System (ADS)

    Singh, Navinder

    The present paper is a review of the phenomena related to nonequilibrium electron relaxation in bulk and nano-scale metallic samples. The workable Two-Temperature Model (TTM) based on Boltzmann-Bloch-Peierls kinetic equation has been applied to study the ultra-fast (femto-second) electronic relaxation in various metallic systems. The advent of new ultra-fast (femto-second) laser technology and pump-probe spectroscopy has produced wealth of new results for micro- and nano-scale electronic technology. The aim of this paper is to clarify the TTM, conditions of its validity and nonvalidity, its modifications for nano-systems, to sum-up the progress, and to point out open problems in this field. We also give a phenomenological integro-differential equation for the kinetics of nondegenerate electrons that goes beyond the TTM.

  7. Volcanic Aerosol Evolution: Model vs. In Situ Sampling

    NASA Astrophysics Data System (ADS)

    Pfeffer, M. A.; Rietmeijer, F. J.; Brearley, A. J.; Fischer, T. P.

    2002-12-01

    Volcanoes are the most significant non-anthropogenic source of tropospheric aerosols. Aerosol samples were collected at different distances from 92°C fumarolic source at Poás Volcano. Aerosols were captured on TEM grids coated by a thin C-film using a specially designed collector. In the sampling, grids were exposed to the plume for 30-second intervals then sealed and frozen to prevent reaction before ATEM analysis to determine aerosol size and chemistry. Gas composition was established using gas chromatography, wet chemistry techniques, AAS and Ion Chromatography on samples collected directly from a fumarolic vent. SO2 flux was measured remotely by COSPEC. A Gaussian plume dispersion model was used to model concentrations of the gases at different distances down-wind. Calculated mixing ratios of air and the initial gas species were used as input to the thermo-chemical model GASWORKS (Symonds and Reed, Am. Jour. Sci., 1993). Modeled products were compared with measured aerosol compositions. Aerosols predicted to precipitate out of the plume one meter above the fumarole are [CaSO4, Fe2.3SO4, H2SO4, MgF2. Na2SO4, silica, water]. Where the plume leaves the confines of the crater, 380 meters distant, the predicted aerosols are the same, excepting FeF3 replacing Fe2.3SO4. Collected aerosols show considerable compositional differences between the sampling locations and are more complex than those predicted. Aerosols from the fumarole consist of [Fe +/- Si,S,Cl], [S +/- O] and [Si +/- O]. Aerosols collected on the crater rim consist of the same plus [O,Na,Mg,Ca], [O,Si,Cl +/- Fe], [Fe,O,F] and [S,O +/- Mg,Ca]. The comparison between results obtained by the equilibrium gas model and the actual aerosol compositions shows that an assumption of chemical and thermal equilibrium evolution is invalid. The complex aerosols collected contrast the simple formulae predicted. These findings show that complex, non-equilibrium chemical reactions take place immediately upon volcanic

  8. New application of temperature-dependent modelling of high temperature superconductors: Quench propagation and pulse magnetization

    NASA Astrophysics Data System (ADS)

    Zhang, Min; Matsuda, Koichi; Coombs, T. A.

    2012-08-01

    We present temperature-dependent modeling of high-temperature superconductors (HTS) to understand HTS electromagnetic phenomena where temperature fluctuation plays a nontrivial role. Thermal physics is introduced into the well-developed H-formulation model, and the effect of temperature-dependent parameters is considered. Based on the model, we perform extensive studies on two important HTS applications: quench propagation and pulse magnetization. A micrometer-scale quench model of HTS coil is developed, which can be used to estimate minimum quench energy and normal zone propagation velocity inside the coil. In addition, we study the influence of inhomogeneity of HTS bulk during pulse magnetization. We demonstrate how the inhomogeneous distribution of critical current inside the bulk results in varying degrees of heat dissipation and uniformity of final trapped field. The temperature-dependent model is proven to be a powerful tool to study the thermally coupled electromagnetic phenomena of HTS.

  9. De novo protein conformational sampling using a probabilistic graphical model

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Debswapna; Cheng, Jianlin

    2015-11-01

    Efficient exploration of protein conformational space remains challenging especially for large proteins when assembling discretized structural fragments extracted from a protein structure data database. We propose a fragment-free probabilistic graphical model, FUSION, for conformational sampling in continuous space and assess its accuracy using ‘blind’ protein targets with a length up to 250 residues from the CASP11 structure prediction exercise. The method reduces sampling bottlenecks, exhibits strong convergence, and demonstrates better performance than the popular fragment assembly method, ROSETTA, on relatively larger proteins with a length of more than 150 residues in our benchmark set. FUSION is freely available through a web server at http://protein.rnet.missouri.edu/FUSION/.

  10. Approaches to retrospective sampling for longitudinal transition regression models

    PubMed Central

    Hunsberger, Sally; Albert, Paul S.; Thoma, Marie

    2016-01-01

    For binary diseases that relapse and remit, it is often of interest to estimate the effect of covariates on the transition process between disease states over time. The transition process can be characterized by modeling the probability of the binary event given the individual’s history. Designing studies that examine the impact of time varying covariates over time can lead to collection of extensive amounts of data. Sometimes it may be possible to collect and store tissue, blood or images and retrospectively analyze this covariate information. In this paper we consider efficient sampling designs that do not require biomarker measurements on all subjects. We describe appropriate estimation methods for transition probabilities and functions of these probabilities, and evaluate efficiency of the estimates from the proposed sampling designs. These new methods are illustrated with data from a longitudinal study of bacterial vaginosis, a common relapsing-remitting vaginal infection of women of child bearing age.

  11. De novo protein conformational sampling using a probabilistic graphical model

    PubMed Central

    Bhattacharya, Debswapna; Cheng, Jianlin

    2015-01-01

    Efficient exploration of protein conformational space remains challenging especially for large proteins when assembling discretized structural fragments extracted from a protein structure data database. We propose a fragment-free probabilistic graphical model, FUSION, for conformational sampling in continuous space and assess its accuracy using ‘blind’ protein targets with a length up to 250 residues from the CASP11 structure prediction exercise. The method reduces sampling bottlenecks, exhibits strong convergence, and demonstrates better performance than the popular fragment assembly method, ROSETTA, on relatively larger proteins with a length of more than 150 residues in our benchmark set. FUSION is freely available through a web server at http://protein.rnet.missouri.edu/FUSION/. PMID:26541939

  12. THE TWO-LEVEL MODEL AT FINITE-TEMPERATURE

    SciTech Connect

    Goodman, A.L.

    1980-07-01

    The finite-temperature HFB cranking equations are solved for the two-level model. The pair gap, moment of inertia and internal energy are determined as functions of spin and temperature. Thermal excitations and rotations collaborate to destroy the pair correlations. Raising the temperature eliminates the backbending effect and improves the HFB approximation.

  13. Research on Temperature Modeling of Strapdown Inertial Navigation System

    NASA Astrophysics Data System (ADS)

    Huang, XiaoJuan; Zhao, LiJian; Xu, RuXiang; Yang, Heng

    2016-02-01

    Strapdown inertial navigation system with laser gyro has been deployed in space tracking ship and compared with the conventional platform inertial navigation system, it has substantial advantage in performance, accuracy and stabilization. Environmental and internal temperature affects the gyro, accelerator, electrical circuits and mechanical structure significantly but the existing temperature compensation model is not accurate enough especially when there is a big temperature change.

  14. Ensemble bayesian model averaging using markov chain Monte Carlo sampling

    SciTech Connect

    Vrugt, Jasper A; Diks, Cees G H; Clark, Martyn P

    2008-01-01

    Bayesian model averaging (BMA) has recently been proposed as a statistical method to calibrate forecast ensembles from numerical weather models. Successful implementation of BMA however, requires accurate estimates of the weights and variances of the individual competing models in the ensemble. In their seminal paper (Raftery etal. Mon Weather Rev 133: 1155-1174, 2(05)) has recommended the Expectation-Maximization (EM) algorithm for BMA model training, even though global convergence of this algorithm cannot be guaranteed. In this paper, we compare the performance of the EM algorithm and the recently developed Differential Evolution Adaptive Metropolis (DREAM) Markov Chain Monte Carlo (MCMC) algorithm for estimating the BMA weights and variances. Simulation experiments using 48-hour ensemble data of surface temperature and multi-model stream-flow forecasts show that both methods produce similar results, and that their performance is unaffected by the length of the training data set. However, MCMC simulation with DREAM is capable of efficiently handling a wide variety of BMA predictive distributions, and provides useful information about the uncertainty associated with the estimated BMA weights and variances.

  15. Comparing interval estimates for small sample ordinal CFA models.

    PubMed

    Natesan, Prathiba

    2015-01-01

    Robust maximum likelihood (RML) and asymptotically generalized least squares (AGLS) methods have been recommended for fitting ordinal structural equation models. Studies show that some of these methods underestimate standard errors. However, these studies have not investigated the coverage and bias of interval estimates. An estimate with a reasonable standard error could still be severely biased. This can only be known by systematically investigating the interval estimates. The present study compares Bayesian, RML, and AGLS interval estimates of factor correlations in ordinal confirmatory factor analysis models (CFA) for small sample data. Six sample sizes, 3 factor correlations, and 2 factor score distributions (multivariate normal and multivariate mildly skewed) were studied. Two Bayesian prior specifications, informative and relatively less informative were studied. Undercoverage of confidence intervals and underestimation of standard errors was common in non-Bayesian methods. Underestimated standard errors may lead to inflated Type-I error rates. Non-Bayesian intervals were more positive biased than negatively biased, that is, most intervals that did not contain the true value were greater than the true value. Some non-Bayesian methods had non-converging and inadmissible solutions for small samples and non-normal data. Bayesian empirical standard error estimates for informative and relatively less informative priors were closer to the average standard errors of the estimates. The coverage of Bayesian credibility intervals was closer to what was expected with overcoverage in a few cases. Although some Bayesian credibility intervals were wider, they reflected the nature of statistical uncertainty that comes with the data (e.g., small sample). Bayesian point estimates were also more accurate than non-Bayesian estimates. The results illustrate the importance of analyzing coverage and bias of interval estimates, and how ignoring interval estimates can be misleading

  16. Comparing interval estimates for small sample ordinal CFA models

    PubMed Central

    Natesan, Prathiba

    2015-01-01

    Robust maximum likelihood (RML) and asymptotically generalized least squares (AGLS) methods have been recommended for fitting ordinal structural equation models. Studies show that some of these methods underestimate standard errors. However, these studies have not investigated the coverage and bias of interval estimates. An estimate with a reasonable standard error could still be severely biased. This can only be known by systematically investigating the interval estimates. The present study compares Bayesian, RML, and AGLS interval estimates of factor correlations in ordinal confirmatory factor analysis models (CFA) for small sample data. Six sample sizes, 3 factor correlations, and 2 factor score distributions (multivariate normal and multivariate mildly skewed) were studied. Two Bayesian prior specifications, informative and relatively less informative were studied. Undercoverage of confidence intervals and underestimation of standard errors was common in non-Bayesian methods. Underestimated standard errors may lead to inflated Type-I error rates. Non-Bayesian intervals were more positive biased than negatively biased, that is, most intervals that did not contain the true value were greater than the true value. Some non-Bayesian methods had non-converging and inadmissible solutions for small samples and non-normal data. Bayesian empirical standard error estimates for informative and relatively less informative priors were closer to the average standard errors of the estimates. The coverage of Bayesian credibility intervals was closer to what was expected with overcoverage in a few cases. Although some Bayesian credibility intervals were wider, they reflected the nature of statistical uncertainty that comes with the data (e.g., small sample). Bayesian point estimates were also more accurate than non-Bayesian estimates. The results illustrate the importance of analyzing coverage and bias of interval estimates, and how ignoring interval estimates can be misleading

  17. Determining permeability of tight rock samples using inverse modeling

    NASA Astrophysics Data System (ADS)

    Finsterle, Stefan; Persoff, Peter

    1997-08-01

    Data from gas-pressure-pulse-decay experiments have been analyzed by means of numerical simulation in combination with automatic model calibration techniques to determine hydrologie properties of low-permeability, low-porosity rock samples. Porosity, permeability, and Klinkenberg slip factor have been estimated for a core plug from The Geysers geothermal field, California. The experiments were conducted using a specially designed permeameter with small gas reservoirs. Pressure changes were measured as gas flowed from the pressurized upstream reservoir through the sample to the downstream reservoir. A simultaneous inversion of data from three experiments performed on different pressure levels allows for independent estimation of absolute permeability and gas permeability which is pressure-dependent due to enhanced slip flow. With this measurement and analysis technique we can determine matrix properties with permeabilities as low as 10-21 m2. In this paper we discuss the procedure of parameter estimation by inverse modeling. We will focus on the error analysis, which reveals estimation uncertainty and parameter correlations. This information can also be used to evaluate and optimize the design of an experiment. The impact of systematic errors due to potential leakage and uncertainty in the initial conditions will also be addressed. The case studies clearly illustrate the need for a thorough error analysis of inverse modeling results.

  18. Modeling and Simulation of a Tethered Harpoon for Comet Sampling

    NASA Technical Reports Server (NTRS)

    Quadrelli, Marco B.

    2014-01-01

    This paper describes the development of a dynamic model and simulation results of a tethered harpoon for comet sampling. This model and simulation was done in order to carry out an initial sensitivity analysis for key design parameters of the tethered system. The harpoon would contain a canister which would collect a sample of soil from a cometary surface. Both a spring ejected canister and a tethered canister are considered. To arrive in close proximity of the spacecraft at the end of its trajectory so it could be captured, the free-flying canister would need to be ejected at the right time and with the proper impulse, while the tethered canister must be recovered by properly retrieving the tether at a rate that would avoid an excessive amplitude of oscillatory behavior during the retrieval. The paper describes the model of the tether dynamics and harpoon penetration physics. The simulations indicate that, without the tether, the canister would still reach the spacecraft for collection, that the tether retrieval of the canister would be achievable with reasonable fuel consumption, and that the canister amplitude upon retrieval would be insensitive to variations in vertical velocity dispersion.

  19. Modelling of tandem cell temperature coefficients

    SciTech Connect

    Friedman, D.J.

    1996-05-01

    This paper discusses the temperature dependence of the basic solar-cell operating parameters for a GaInP/GaAs series-connected two-terminal tandem cell. The effects of series resistance and of different incident solar spectra are also discussed.

  20. Monitoring, Modeling, and Diagnosis of Alkali-Silica Reaction in Small Concrete Samples

    SciTech Connect

    Agarwal, Vivek; Cai, Guowei; Gribok, Andrei V.; Mahadevan, Sankaran

    2015-09-01

    Assessment and management of aging concrete structures in nuclear power plants require a more systematic approach than simple reliance on existing code margins of safety. Structural health monitoring of concrete structures aims to understand the current health condition of a structure based on heterogeneous measurements to produce high-confidence actionable information regarding structural integrity that supports operational and maintenance decisions. This report describes alkali-silica reaction (ASR) degradation mechanisms and factors influencing the ASR. A fully coupled thermo-hydro-mechanical-chemical model developed by Saouma and Perotti by taking into consideration the effects of stress on the reaction kinetics and anisotropic volumetric expansion is presented in this report. This model is implemented in the GRIZZLY code based on the Multiphysics Object Oriented Simulation Environment. The implemented model in the GRIZZLY code is randomly used to initiate ASR in a 2D and 3D lattice to study the percolation aspects of concrete. The percolation aspects help determine the transport properties of the material and therefore the durability and service life of concrete. This report summarizes the effort to develop small-size concrete samples with embedded glass to mimic ASR. The concrete samples were treated in water and sodium hydroxide solution at elevated temperature to study how ingress of sodium ions and hydroxide ions at elevated temperature impacts concrete samples embedded with glass. Thermal camera was used to monitor the changes in the concrete sample and results are summarized.

  1. 40 CFR 53.57 - Test for filter temperature control during sampling and post-sampling periods.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... energy distribution and permitted tolerances specified in table E-2 of this subpart. The solar radiation... (40 CFR part 50, appendix L, figure L-30) or equivalent adaptor to facilitate measurement of sampler... recommended. (6) Sample filter or filters, as specified in section 6 of 40 CFR part 50, appendix L....

  2. 40 CFR 53.57 - Test for filter temperature control during sampling and post-sampling periods.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... energy distribution and permitted tolerances specified in table E-2 of this subpart. The solar radiation... (40 CFR part 50, appendix L, figure L-30) or equivalent adaptor to facilitate measurement of sampler... recommended. (6) Sample filter or filters, as specified in section 6 of 40 CFR part 50, appendix L....

  3. 40 CFR 53.57 - Test for filter temperature control during sampling and post-sampling periods.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... (40 CFR part 50, appendix L, figure L-30) or equivalent adaptor to facilitate measurement of sampler... recommended. (6) Sample filter or filters, as specified in section 6 of 40 CFR part 50, appendix L. (d... calibration, certification of calibration accuracy, and NIST-traceability (if required) of all...

  4. Activated sampling in complex materials at finite temperature: The properly obeying probability activation-relaxation technique

    NASA Astrophysics Data System (ADS)

    Vocks, Henk; Chubynsky, M. V.; Barkema, G. T.; Mousseau, Normand

    2005-12-01

    While the dynamics of many complex systems is dominated by activated events, there are very few simulation methods that take advantage of this fact. Most of these procedures are restricted to relatively simple systems or, as with the activation-relaxation technique (ART), sample the conformation space efficiently at the cost of a correct thermodynamical description. We present here an extension of ART, the properly obeying probability ART (POP-ART), that obeys detailed balance and samples correctly the thermodynamic ensemble. Testing POP-ART on two model systems, a vacancy and an interstitial in crystalline silicon, we show that this method recovers the proper thermodynamical weights associated with the various accessible states and is significantly faster than molecular dynamics in the simulations of a vacancy below 700 K.

  5. Activated sampling in complex materials at finite temperature: the properly obeying probability activation-relaxation technique.

    PubMed

    Vocks, Henk; Chubynsky, M V; Barkema, G T; Mousseau, Normand

    2005-12-22

    While the dynamics of many complex systems is dominated by activated events, there are very few simulation methods that take advantage of this fact. Most of these procedures are restricted to relatively simple systems or, as with the activation-relaxation technique (ART), sample the conformation space efficiently at the cost of a correct thermodynamical description. We present here an extension of ART, the properly obeying probability ART (POP-ART), that obeys detailed balance and samples correctly the thermodynamic ensemble. Testing POP-ART on two model systems, a vacancy and an interstitial in crystalline silicon, we show that this method recovers the proper thermodynamical weights associated with the various accessible states and is significantly faster than molecular dynamics in the simulations of a vacancy below 700 K. PMID:16396563

  6. New high temperature plasmas and sample introduction systems for analytical atomic emission and mass spectrometry. Progress report, January 1, 1990--December 31, 1992

    SciTech Connect

    Montaser, A.

    1992-09-01

    New high temperature plasmas and new sample introduction systems are explored for rapid elemental and isotopic analysis of gases, solutions, and solids using mass spectrometry and atomic emission spectrometry. Emphasis was placed on atmospheric pressure He inductively coupled plasmas (ICP) suitable for atomization, excitation, and ionization of elements; simulation and computer modeling of plasma sources with potential for use in spectrochemical analysis; spectroscopic imaging and diagnostic studies of high temperature plasmas, particularly He ICP discharges; and development of new, low-cost sample introduction systems, and examination of techniques for probing the aerosols over a wide range. Refs., 14 figs. (DLC)

  7. Martian Radiative Transfer Modeling Using the Optimal Spectral Sampling Method

    NASA Technical Reports Server (NTRS)

    Eluszkiewicz, J.; Cady-Pereira, K.; Uymin, G.; Moncet, J.-L.

    2005-01-01

    The large volume of existing and planned infrared observations of Mars have prompted the development of a new martian radiative transfer model that could be used in the retrievals of atmospheric and surface properties. The model is based on the Optimal Spectral Sampling (OSS) method [1]. The method is a fast and accurate monochromatic technique applicable to a wide range of remote sensing platforms (from microwave to UV) and was originally developed for the real-time processing of infrared and microwave data acquired by instruments aboard the satellites forming part of the next-generation global weather satellite system NPOESS (National Polarorbiting Operational Satellite System) [2]. As part of our on-going research related to the radiative properties of the martian polar caps, we have begun the development of a martian OSS model with the goal of using it to perform self-consistent atmospheric corrections necessary to retrieve caps emissivity from the Thermal Emission Spectrometer (TES) spectra. While the caps will provide the initial focus area for applying the new model, it is hoped that the model will be of interest to the wider Mars remote sensing community.

  8. Automated, low-temperature dielectric relaxation apparatus for measurement of air-sensitive, corrosive, hygroscopic, powdered samples

    NASA Astrophysics Data System (ADS)

    Bessonette, Paul W. R.; White, Mary Anne

    1999-07-01

    An automated apparatus for dielectric determinations on solid samples was designed to allow cryogenic measurements on air-sensitive, corrosive, hygroscopic, powdered samples, without determination of sample thickness, provided that it is uniform. A three-terminal design enabled measurements that were not affected by errors due to dimensional changes of the sample or the electrodes with changes in temperature. Meaningful dielectric data could be taken over the frequency range from 20 Hz to 1 MHz and the temperature range from 12 to 360 K. Tests with Teflon and with powdered NH4Cl gave results that were accurate within a few percent when compared with literature values.

  9. Spatiotemporal model or time series model for assessing city-wide temperature effects on mortality?

    PubMed

    Guo, Yuming; Barnett, Adrian G; Tong, Shilu

    2013-01-01

    Most studies examining the temperature-mortality association in a city used temperatures from one site or the average from a network of sites. This may cause measurement error as temperature varies across a city due to effects such as urban heat islands. We examined whether spatiotemporal models using spatially resolved temperatures produced different associations between temperature and mortality compared with time series models that used non-spatial temperatures. We obtained daily mortality data in 163 areas across Brisbane city, Australia from 2000 to 2004. We used ordinary kriging to interpolate spatial temperature variation across the city based on 19 monitoring sites. We used a spatiotemporal model to examine the impact of spatially resolved temperatures on mortality. Also, we used a time series model to examine non-spatial temperatures using a single site and the average temperature from three sites. We used squared Pearson scaled residuals to compare model fit. We found that kriged temperatures were consistent with observed temperatures. Spatiotemporal models using kriged temperature data yielded slightly better model fit than time series models using a single site or the average of three sites' data. Despite this better fit, spatiotemporal and time series models produced similar associations between temperature and mortality. In conclusion, time series models using non-spatial temperatures were equally good at estimating the city-wide association between temperature and mortality as spatiotemporal models. PMID:23026801

  10. Temperature-variable high-frequency dynamic modeling of PIN diode

    NASA Astrophysics Data System (ADS)

    Shangbin, Ye; Jiajia, Zhang; Yicheng, Zhang; Yongtao, Yao

    2016-04-01

    The PIN diode model for high frequency dynamic transient characteristic simulation is important in conducted EMI analysis. The model should take junction temperature into consideration since equipment usually works at a wide range of temperature. In this paper, a temperature-variable high frequency dynamic model for the PIN diode is built, which is based on the Laplace-transform analytical model at constant temperature. The relationship between model parameters and temperature is expressed as temperature functions by analyzing the physical principle of these parameters. A fast recovery power diode MUR1560 is chosen as the test sample and its dynamic performance is tested under inductive load by a temperature chamber experiment, which is used for model parameter extraction and model verification. Results show that the model proposed in this paper is accurate for reverse recovery simulation with relatively small errors at the temperature range from 25 to 120 °C. Project supported by the National High Technology and Development Program of China (No. 2011AA11A265).

  11. High temperature furnace modeling and performance verifications

    NASA Technical Reports Server (NTRS)

    Smith, James E., Jr.

    1988-01-01

    Analytical, numerical and experimental studies were performed on two classes of high temperature materials processing furnaces. The research concentrates on a commercially available high temperature furnace using zirconia as the heating element and an arc furnace based on a ST International tube welder. The zirconia furnace was delivered and work is progressing on schedule. The work on the arc furnace was initially stalled due to the unavailability of the NASA prototype, which is actively being tested aboard the KC-135 experimental aircraft. A proposal was written and funded to purchase an additional arc welder to alleviate this problem. The ST International weld head and power supply were received and testing will begin in early November. The first 6 months of the grant are covered.

  12. Modeling Climate Change Effects on Stream Temperatures in Regulated Rivers

    NASA Astrophysics Data System (ADS)

    Null, S. E.; Akhbari, M.; Ligare, S. T.; Rheinheimer, D. E.; Peek, R.; Yarnell, S. M.; Viers, J. H.

    2013-12-01

    We provide a method for examining mesoscale stream temperature objectives downstream of dams with anticipated climate change using an integrated multi-model approach. Changing hydroclimatic conditions will likely impact stream temperatures within reservoirs and below dams, and affect downstream ecology. We model hydrology and water temperature using a series of linked models that includes a hydrology model to predict natural unimpaired flows in upstream reaches, a reservoir temperature simulation model , an operations model to simulate reservoir releases, and a stream temperature simulation model to simulate downstream conditions . All models are 1-dimensional and operate on either a weekly or daily timestep. First, we model reservoir thermal dynamics and release operations of hypothetical reservoirs of different sizes, elevations, and latitudes with climate-forced inflow hydrologies to examine the potential to manage stream temperatures for coldwater habitat. Results are presented as stream temperature change from the historical time period and indicate that reservoir releases are cooler than upstream conditions, although the absolute temperatures of reaches below dams warm with climate change. We also apply our method to a case study in California's Yuba River watershed to evaluate water regulation and hydropower operation effects on stream temperatures with climate change. Catchments of the upper Yuba River are highly-engineered, with multiple, interconnected infrastructure to provide hydropower, water supply, flood control, environmental flows, and recreation. Results illustrate climate-driven versus operations-driven changes to stream temperatures. This work highlights the need for methods to consider reservoir regulation effects on stream temperatures with climate change, particularly for hydropower relicensing (which currently ignores climate change) such that impacts to other beneficial uses like coldwater habitat and instream ecosystems can be

  13. An Accurate Temperature Correction Model for Thermocouple Hygrometers 1

    PubMed Central

    Savage, Michael J.; Cass, Alfred; de Jager, James M.

    1982-01-01

    Numerous water relation studies have used thermocouple hygrometers routinely. However, the accurate temperature correction of hygrometer calibration curve slopes seems to have been largely neglected in both psychrometric and dewpoint techniques. In the case of thermocouple psychrometers, two temperature correction models are proposed, each based on measurement of the thermojunction radius and calculation of the theoretical voltage sensitivity to changes in water potential. The first model relies on calibration at a single temperature and the second at two temperatures. Both these models were more accurate than the temperature correction models currently in use for four psychrometers calibrated over a range of temperatures (15-38°C). The model based on calibration at two temperatures is superior to that based on only one calibration. The model proposed for dewpoint hygrometers is similar to that for psychrometers. It is based on the theoretical voltage sensitivity to changes in water potential. Comparison with empirical data from three dewpoint hygrometers calibrated at four different temperatures indicates that these instruments need only be calibrated at, e.g. 25°C, if the calibration slopes are corrected for temperature. PMID:16662241

  14. An accurate temperature correction model for thermocouple hygrometers.

    PubMed

    Savage, M J; Cass, A; de Jager, J M

    1982-02-01

    Numerous water relation studies have used thermocouple hygrometers routinely. However, the accurate temperature correction of hygrometer calibration curve slopes seems to have been largely neglected in both psychrometric and dewpoint techniques.In the case of thermocouple psychrometers, two temperature correction models are proposed, each based on measurement of the thermojunction radius and calculation of the theoretical voltage sensitivity to changes in water potential. The first model relies on calibration at a single temperature and the second at two temperatures. Both these models were more accurate than the temperature correction models currently in use for four psychrometers calibrated over a range of temperatures (15-38 degrees C). The model based on calibration at two temperatures is superior to that based on only one calibration.The model proposed for dewpoint hygrometers is similar to that for psychrometers. It is based on the theoretical voltage sensitivity to changes in water potential. Comparison with empirical data from three dewpoint hygrometers calibrated at four different temperatures indicates that these instruments need only be calibrated at, e.g. 25 degrees C, if the calibration slopes are corrected for temperature. PMID:16662241

  15. Modeling the Orbital Sampling Effect of Extrasolar Moons

    NASA Astrophysics Data System (ADS)

    Heller, René; Hippke, Michael; Jackson, Brian

    2016-04-01

    The orbital sampling effect (OSE) appears in phase-folded transit light curves of extrasolar planets with moons. Analytical OSE models have hitherto neglected stellar limb darkening and non-zero transit impact parameters and assumed that the moon is on a circular, co-planar orbit around the planet. Here, we present an analytical OSE model for eccentric moon orbits, which we implement in a numerical simulator with stellar limb darkening that allows for arbitrary transit impact parameters. We also describe and publicly release a fully numerical OSE simulator (PyOSE) that can model arbitrary inclinations of the transiting moon orbit. Both our analytical solution for the OSE and PyOSE can be used to search for exomoons in long-term stellar light curves such as those by Kepler and the upcoming PLATO mission. Our updated OSE model offers an independent method for the verification of possible future exomoon claims via transit timing variations and transit duration variations. Photometrically quiet K and M dwarf stars are particularly promising targets for an exomoon discovery using the OSE.

  16. A Simple Dewar/Cryostat for Thermally Equilibrating Samples at Known Temperatures for Accurate Cryogenic Luminescence Measurements.

    PubMed

    Weaver, Phoebe G; Jagow, Devin M; Portune, Cameron M; Kenney, John W

    2016-01-01

    The design and operation of a simple liquid nitrogen Dewar/cryostat apparatus based upon a small fused silica optical Dewar, a thermocouple assembly, and a CCD spectrograph are described. The experiments for which this Dewar/cryostat is designed require fast sample loading, fast sample freezing, fast alignment of the sample, accurate and stable sample temperatures, and small size and portability of the Dewar/cryostat cryogenic unit. When coupled with the fast data acquisition rates of the CCD spectrograph, this Dewar/cryostat is capable of supporting cryogenic luminescence spectroscopic measurements on luminescent samples at a series of known, stable temperatures in the 77-300 K range. A temperature-dependent study of the oxygen quenching of luminescence in a rhodium(III) transition metal complex is presented as an example of the type of investigation possible with this Dewar/cryostat. In the context of this apparatus, a stable temperature for cryogenic spectroscopy means a luminescent sample that is thermally equilibrated with either liquid nitrogen or gaseous nitrogen at a known measureable temperature that does not vary (ΔT < 0.1 K) during the short time scale (~1-10 sec) of the spectroscopic measurement by the CCD. The Dewar/cryostat works by taking advantage of the positive thermal gradient dT/dh that develops above liquid nitrogen level in the Dewar where h is the height of the sample above the liquid nitrogen level. The slow evaporation of the liquid nitrogen results in a slow increase in h over several hours and a consequent slow increase in the sample temperature T over this time period. A quickly acquired luminescence spectrum effectively catches the sample at a constant, thermally equilibrated temperature. PMID:27501355

  17. Wang-Landau sampling in face-centered-cubic hydrophobic-hydrophilic lattice model proteins

    NASA Astrophysics Data System (ADS)

    Liu, Jingfa; Song, Beibei; Yao, Yonglei; Xue, Yu; Liu, Wenjie; Liu, Zhaoxia

    2014-10-01

    Finding the global minimum-energy structure is one of the main problems of protein structure prediction. The face-centered-cubic (fcc) hydrophobic-hydrophilic (HP) lattice model can reach high approximation ratios of real protein structures, so the fcc lattice model is a good choice to predict the protein structures. The lacking of an effective global optimization method is the key obstacle in solving this problem. The Wang-Landau sampling method is especially useful for complex systems with a rough energy landscape and has been successfully applied to solving many optimization problems. We apply the improved Wang-Landau (IWL) sampling method, which incorporates the generation of an initial conformation based on the greedy strategy and the neighborhood strategy based on pull moves into the Wang-Landau sampling method to predict the protein structures on the fcc HP lattice model. Unlike conventional Monte Carlo simulations that generate a probability distribution at a given temperature, the Wang-Landau sampling method can estimate the density of states accurately via a random walk, which produces a flat histogram in energy space. We test 12 general benchmark instances on both two-dimensional and three-dimensional (3D) fcc HP lattice models. The lowest energies by the IWL sampling method are as good as or better than those of other methods in the literature for all instances. We then test five sets of larger-scale instances, denoted by the S, R, F90, F180, and CASP target instances on the 3D fcc HP lattice model. The numerical results show that our algorithm performs better than the other five methods in the literature on both the lowest energies and the average lowest energies in all runs. The IWL sampling method turns out to be a powerful tool to study the structure prediction of the fcc HP lattice model proteins.

  18. Laser-induced breakdown spectroscopy on metallic samples at very low temperature in different ambient gas pressures

    NASA Astrophysics Data System (ADS)

    El-Saeid, R. H.; Abdelhamid, M.; Harith, M. A.

    2016-02-01

    Analysis of metals at very low temperature adopting laser-induced breakdown spectroscopy (LIBS) is greatly beneficial in space exploration expeditions and in some important industrial applications. In the present work, the effect of very low sample temperature on the spectral emission intensity of laser-induced plasma under both atmospheric pressure and vacuum has been studied for different bronze alloy samples. The sample was cooled down to liquid nitrogen (LN) temperature 77 K in a special vacuum chamber. Laser-induced plasma has been produced onto the sample surface using the fundamental wavelength of Nd:YAG laser. The optical emission from the plasma is collected by an optical fiber and analyzed by an echelle spectrometer combined with an intensified CCD camera. The integrated intensities of certain spectral emission lines of Cu, Pb, Sn, and Zn have been estimated from the obtained LIBS spectra and compared with that measured at room temperature. The laser-induced plasma parameters (electron number density Ne and electron temperature Te) were investigated at room and liquid nitrogen temperatures for both atmospheric pressure and vacuum ambient conditions. The results suggest that reducing the sample temperature leads to decrease in the emission line intensities under both environments. Plasma parameters were found to decrease at atmospheric pressure but increased under vacuum conditions.

  19. A thermocouple-based remote temperature controller of an electrically floated sample to study plasma CVD growth of carbon nanotube

    NASA Astrophysics Data System (ADS)

    Miura, Takuya; Xie, Wei; Yanase, Takashi; Nagahama, Taro; Shimada, Toshihiro

    2015-09-01

    Plasma chemical vapor deposition (CVD) is now gathering attention from a novel viewpoint, because it is easy to combine plasma processes and electrochemistry by applying a bias voltage to the sample. In order to explore electrochemistry during the plasma CVD, the temperature of the sample must be controlled precisely. In traditional equipment, the sample temperature is measured by a radiation thermometer. Since emissivity of the sample surface changes in the course of the CVD growth, it is difficult to measure the exact temperature using the radiation thermometer. In this work, we developed new equipment to control the temperature of electrically floated samples by thermocouple with Wi-Fi transmission. The growth of the CNT was investigated using our plasma CVD equipment. We examined the temperature accuracy and stability controlled by the thermocouple with monitoring the radiation thermometer. We noticed that the thermocouple readings were stable, whereas the readings of the radiation thermometer changes significantly (20 °C) during plasma CVD. This result clearly shows that the sample temperature should be measured with direct connection. On the result of CVD experiment, different structures of carbon including CNT were obtained by changing the bias voltages.

  20. Temperature Dependent Constitutive Modeling for Magnesium Alloy Sheet

    SciTech Connect

    Lee, Jong K.; Lee, June K.; Kim, Hyung S.; Kim, Heon Y.

    2010-06-15

    Magnesium alloys have been increasingly used in automotive and electronic industries because of their excellent strength to weight ratio and EMI shielding properties. However, magnesium alloys have low formability at room temperature due to their unique mechanical behavior (twinning and untwining), prompting for forming at an elevated temperature. In this study, a temperature dependent constitutive model for magnesium alloy (AZ31B) sheet is developed. A hardening law based on non linear kinematic hardening model is used to consider Bauschinger effect properly. Material parameters are determined from a series of uni-axial cyclic experiments (T-C-T or C-T-C) with the temperature ranging 150-250 deg. C. The influence of temperature on the constitutive equation is introduced by the material parameters assumed to be functions of temperature. Fitting process of the assumed model to measured data is presented and the results are compared.

  1. Temperature Dependent Constitutive Modeling for Magnesium Alloy Sheet

    NASA Astrophysics Data System (ADS)

    Lee, Jong K.; Lee, June K.; Kim, Hyung S.; Kim, Heon Y.

    2010-06-01

    Magnesium alloys have been increasingly used in automotive and electronic industries because of their excellent strength to weight ratio and EMI shielding properties. However, magnesium alloys have low formability at room temperature due to their unique mechanical behavior (twinning and untwining), prompting for forming at an elevated temperature. In this study, a temperature dependent constitutive model for magnesium alloy (AZ31B) sheet is developed. A hardening law based on non linear kinematic hardening model is used to consider Bauschinger effect properly. Material parameters are determined from a series of uni-axial cyclic experiments (T-C-T or C-T-C) with the temperature ranging 150-250° C. The influence of temperature on the constitutive equation is introduced by the material parameters assumed to be functions of temperature. Fitting process of the assumed model to measured data is presented and the results are compared.

  2. Simulation of Soil Temperature Dynamics with Models Using Different Concepts

    PubMed Central

    Sándor, Renáta; Fodor, Nándor

    2012-01-01

    This paper presents two soil temperature models with empirical and mechanistic concepts. At the test site (calcaric arenosol), meteorological parameters as well as soil moisture content and temperature at 5 different depths were measured in an experiment with 8 parcels realizing the combinations of the fertilized, nonfertilized, irrigated, nonirrigated treatments in two replicates. Leaf area dynamics was also monitored. Soil temperature was calculated with the original and a modified version of CERES as well as with the HYDRUS-1D model. The simulated soil temperature values were compared to the observed ones. The vegetation reduced both the average soil temperature and its diurnal amplitude; therefore, considering the leaf area dynamics is important in modeling. The models underestimated the actual soil temperature and overestimated the temperature oscillation within the winter period. All models failed to account for the insulation effect of snow cover. The modified CERES provided explicitly more accurate soil temperature values than the original one. Though HYDRUS-1D provided more accurate soil temperature estimations, its superiority to CERES is not unequivocal as it requires more detailed inputs. PMID:22792047

  3. Simulation of soil temperature dynamics with models using different concepts.

    PubMed

    Sándor, Renáta; Fodor, Nándor

    2012-01-01

    This paper presents two soil temperature models with empirical and mechanistic concepts. At the test site (calcaric arenosol), meteorological parameters as well as soil moisture content and temperature at 5 different depths were measured in an experiment with 8 parcels realizing the combinations of the fertilized, nonfertilized, irrigated, nonirrigated treatments in two replicates. Leaf area dynamics was also monitored. Soil temperature was calculated with the original and a modified version of CERES as well as with the HYDRUS-1D model. The simulated soil temperature values were compared to the observed ones. The vegetation reduced both the average soil temperature and its diurnal amplitude; therefore, considering the leaf area dynamics is important in modeling. The models underestimated the actual soil temperature and overestimated the temperature oscillation within the winter period. All models failed to account for the insulation effect of snow cover. The modified CERES provided explicitly more accurate soil temperature values than the original one. Though HYDRUS-1D provided more accurate soil temperature estimations, its superiority to CERES is not unequivocal as it requires more detailed inputs. PMID:22792047

  4. Using maximum entropy modeling for optimal selection of sampling sites for monitoring networks

    USGS Publications Warehouse

    Stohlgren, Thomas J.; Kumar, Sunil; Barnett, David T.; Evangelista, Paul H.

    2011-01-01

    Environmental monitoring programs must efficiently describe state shifts. We propose using maximum entropy modeling to select dissimilar sampling sites to capture environmental variability at low cost, and demonstrate a specific application: sample site selection for the Central Plains domain (453,490 km2) of the National Ecological Observatory Network (NEON). We relied on four environmental factors: mean annual temperature and precipitation, elevation, and vegetation type. A “sample site” was defined as a 20 km × 20 km area (equal to NEON’s airborne observation platform [AOP] footprint), within which each 1 km2 cell was evaluated for each environmental factor. After each model run, the most environmentally dissimilar site was selected from all potential sample sites. The iterative selection of eight sites captured approximately 80% of the environmental envelope of the domain, an improvement over stratified random sampling and simple random designs for sample site selection. This approach can be widely used for cost-efficient selection of survey and monitoring sites.

  5. Advanced flight design systems subsystem performance models. Sample model: Environmental analysis routine library

    NASA Technical Reports Server (NTRS)

    Parker, K. C.; Torian, J. G.

    1980-01-01

    A sample environmental control and life support model performance analysis using the environmental analysis routines library is presented. An example of a complete model set up and execution is provided. The particular model was synthesized to utilize all of the component performance routines and most of the program options.

  6. Modelling temperature and concentration dependent solid/liquid interfacial energies

    NASA Astrophysics Data System (ADS)

    Lippmann, Stephanie; Jung, In-Ho; Paliwal, Manas; Rettenmayr, Markus

    2016-01-01

    Models for the prediction of the solid/liquid interfacial energy in pure substances and binary alloys, respectively, are reviewed and extended regarding the temperature and concentration dependence of the required thermodynamic entities. A CALPHAD-type thermodynamic database is used to introduce temperature and concentration dependent melting enthalpies and entropies for multicomponent alloys in the temperature range between liquidus and solidus. Several suitable models are extended and employed to calculate the temperature and concentration dependent interfacial energy for Al-FCC with their respective liquids and compared with experimental data.

  7. A time series model for influent temperature estimation: application to dynamic temperature modelling of an aerated lagoon.

    PubMed

    Escalas-Cañellas, Antoni; Abrego-Góngora, Carlos J; Barajas-López, María Guadalupe; Houweling, Dwight; Comeau, Yves

    2008-05-01

    Thirty-nine linear regression and time series models were built and calibrated for influent temperature (Ti) estimation at the primary aerated facultative lagoon in a municipal wastewater treatment plant. The models were based on mean daily ambient air temperature (Ta) and/or daily rainfall (P), and-optionally-wastewater temperature autoregression. The best fits were achieved with some time series models involving Ta and P, and Ti autoregression. The best-fit model was able to estimate influent temperature with a root-mean-square-error of 0.5 degrees C, and an R2 of 0.925, for the calibration period of 10.5 months. In addition, a dynamic lagoon-temperature (Tw) model from the literature was modified in its terms of solar radiation and aeration latent heat, and applied to the primary lagoon. The model was fed with the estimated influent temperature, and five model parameters were identified by calibration against 10.5-month Tw data. Dynamic lagoon-temperature estimation results were comparable to or better than other results of long-term simulations found in the literature. Sensitivity analyses were run on both models. Further validation with independent sets of data is needed for verification of the predictive capability of the models. PMID:18342909

  8. Sample Collection from Small Airless Bodies: Examination of Temperature Constraints for the TGIP Sample Collector for the Hera Near-Earth Asteroid Sample Return Mission

    NASA Technical Reports Server (NTRS)

    Franzen, M. A.; Roe, L. A.; Buffington, J. A.; Sears, D. W. G.

    2005-01-01

    There have been a number of missions that have explored the solar system with cameras and other instruments but profound questions remain that can only be addressed through the analysis of returned samples. However, due to lack of appropriate technology, high cost, and high risk, sample return has only recently become a feasible part of robotic solar system exploration. One specific objective of the President s new vision is that robotic exploration of the solar system should enhance human exploration as it discovers and understands the the solar system, and searches for life and resources [1]. Missions to small bodies, asteroids and comets, will partially fill the huge technological void between missions to the Moon and missions to Mars. However, such missions must be low cost and inherently simple, so they can be applied routinely to many missions. Sample return from asteroids, comets, Mars, and Jupiter s moons will be an important and natural part of the human exploration of space effort. Here we describe the collector designed for the Hera Near-Earth Asteroid Sample Return Mission. We have built a small prototype for preliminary evaluation, but expect the final collector to gather approx.100 g of sample of dust grains to centimeter sized clasts on each application to the surface of the asteroid.

  9. West Flank Coso, CA FORGE 3D temperature model

    DOE Data Explorer

    Doug Blankenship

    2016-03-01

    x,y,z data of the 3D temperature model for the West Flank Coso FORGE site. Model grid spacing is 250m. The temperature model for the Coso geothermal field used over 100 geothermal production sized wells and intermediate-depth temperature holes. At the near surface of this model, two boundary temperatures were assumed: (1) areas with surface manifestations, including fumaroles along the northeast striking normal faults and northwest striking dextral faults with the hydrothermal field, a temperature of ~104˚C was applied to datum at +1066 meters above sea level elevation, and (2) a near-surface temperature at about 10 meters depth, of 20˚C was applied below the diurnal and annual conductive temperature perturbations. These assumptions were based on heat flow studies conducted at the CVF and for the Mojave Desert. On the edges of the hydrothermal system, a 73˚C/km (4˚F/100’) temperature gradient contour was established using conductive gradient data from shallow and intermediate-depth temperature holes. This contour was continued to all elevation datums between the 20˚C surface and -1520 meters below mean sea level. Because the West Flank is outside of the geothermal field footprint, during Phase 1, the three wells inside the FORGE site were incorporated into the preexisting temperature model. To ensure a complete model was built based on all the available data sets, measured bottom-hole temperature gradients in certain wells were downward extrapolated to the next deepest elevation datum (or a maximum of about 25% of the well depth where conductive gradients are evident in the lower portions of the wells). After assuring that the margins of the geothermal field were going to be adequately modelled, the data was contoured using the Kriging method algorithm. Although the extrapolated temperatures and boundary conditions are not rigorous, the calculated temperatures are anticipated to be within ~6˚C (20˚F), or one contour interval, of the

  10. Multi-Relaxation Temperature-Dependent Dielectric Model of the Arctic Soil at Positive Temperatures

    NASA Astrophysics Data System (ADS)

    Savin, I. V.; Mironov, V. L.

    2014-11-01

    Frequency spectra of the dielectric permittivity of the Arctic soil of Alaska are investigated with allowance for the dipole and ionic relaxation of molecules of the soil moisture at frequencies from 40 MHz to 16 GHz and temperatures from -5 to +25°С. A generalized temperature-dependent multi-relaxation refraction dielectric model of the humid Arctic soil is suggested.