Quantification and assessment of heat and cold waves in Novi Sad, Northern Serbia

NASA Astrophysics Data System (ADS)

Basarin, Biljana; Lukić, Tin; Matzarakis, Andreas

2016-01-01

Physiologically equivalent temperature (PET) has been applied to the analysis of heat and cold waves and human thermal conditions in Novi Sad, Serbia. A series of daily minimum and maximum air temperature, relative humidity, wind, and cloud cover was used to calculate PET for the investigated period 1949-2012. The heat and cold wave analysis was carried out on days with PET values exceeding defined thresholds. Additionally, the acclimatization approach was introduced to evaluate human adaptation to interannual thermal perception. Trend analysis has revealed the presence of increasing trend in summer PET anomalies, number of days above defined threshold, number of heat waves, and average duration of heat waves per year since 1981. Moreover, winter PET anomaly as well as the number of days below certain threshold and number of cold waves per year until 1980 was decreasing, but the decrease was not statistically significant. The highest number of heat waves during summer was registered in the last two decades, but also in the first decade of the investigated period. On the other hand, the number of cold waves during six decades is quite similar and the differences are very small.

Quantification and assessment of heat and cold waves in Novi Sad, Northern Serbia.

PubMed

Basarin, Biljana; Lukić, Tin; Matzarakis, Andreas

2016-01-01

Physiologically equivalent temperature (PET) has been applied to the analysis of heat and cold waves and human thermal conditions in Novi Sad, Serbia. A series of daily minimum and maximum air temperature, relative humidity, wind, and cloud cover was used to calculate PET for the investigated period 1949-2012. The heat and cold wave analysis was carried out on days with PET values exceeding defined thresholds. Additionally, the acclimatization approach was introduced to evaluate human adaptation to interannual thermal perception. Trend analysis has revealed the presence of increasing trend in summer PET anomalies, number of days above defined threshold, number of heat waves, and average duration of heat waves per year since 1981. Moreover, winter PET anomaly as well as the number of days below certain threshold and number of cold waves per year until 1980 was decreasing, but the decrease was not statistically significant. The highest number of heat waves during summer was registered in the last two decades, but also in the first decade of the investigated period. On the other hand, the number of cold waves during six decades is quite similar and the differences are very small.

Effects of Solder Temperature on Pin Through-Hole during Wave Soldering: Thermal-Fluid Structure Interaction Analysis

PubMed Central

Abdul Aziz, M. S.; Abdullah, M. Z.; Khor, C. Y.

2014-01-01

An efficient simulation technique was proposed to examine the thermal-fluid structure interaction in the effects of solder temperature on pin through-hole during wave soldering. This study investigated the capillary flow behavior as well as the displacement, temperature distribution, and von Mises stress of a pin passed through a solder material. A single pin through-hole connector mounted on a printed circuit board (PCB) was simulated using a 3D model solved by FLUENT. The ABAQUS solver was employed to analyze the pin structure at solder temperatures of 456.15 K (183°C) < T < 643.15 K (370°C). Both solvers were coupled by the real time coupling software and mesh-based parallel code coupling interface during analysis. In addition, an experiment was conducted to measure the temperature difference (ΔT) between the top and the bottom of the pin. Analysis results showed that an increase in temperature increased the structural displacement and the von Mises stress. Filling time exhibited a quadratic relationship to the increment of temperature. The deformation of pin showed a linear correlation to the temperature. The ΔT obtained from the simulation and the experimental method were validated. This study elucidates and clearly illustrates wave soldering for engineers in the PCB assembly industry. PMID:25225638

Effects of solder temperature on pin through-hole during wave soldering: thermal-fluid structure interaction analysis.

PubMed

Aziz, M S Abdul; Abdullah, M Z; Khor, C Y

2014-01-01

An efficient simulation technique was proposed to examine the thermal-fluid structure interaction in the effects of solder temperature on pin through-hole during wave soldering. This study investigated the capillary flow behavior as well as the displacement, temperature distribution, and von Mises stress of a pin passed through a solder material. A single pin through-hole connector mounted on a printed circuit board (PCB) was simulated using a 3D model solved by FLUENT. The ABAQUS solver was employed to analyze the pin structure at solder temperatures of 456.15 K (183(°)C) < T < 643.15 K (370(°)C). Both solvers were coupled by the real time coupling software and mesh-based parallel code coupling interface during analysis. In addition, an experiment was conducted to measure the temperature difference (ΔT) between the top and the bottom of the pin. Analysis results showed that an increase in temperature increased the structural displacement and the von Mises stress. Filling time exhibited a quadratic relationship to the increment of temperature. The deformation of pin showed a linear correlation to the temperature. The ΔT obtained from the simulation and the experimental method were validated. This study elucidates and clearly illustrates wave soldering for engineers in the PCB assembly industry.

Added effect of heat wave on mortality in Seoul, Korea.

PubMed

Lee, Won Kyung; Lee, Hye Ah; Lim, Youn Hee; Park, Hyesook

2016-05-01

A heat wave could increase mortality owing to high temperature. However, little is known about the added (duration) effect of heat wave from the prolonged period of high temperature on mortality and different effect sizes depending on the definition of heat waves and models. A distributed lag non-linear model with a quasi-Poisson distribution was used to evaluate the added effect of heat wave on mortality after adjusting for long-term and intra-seasonal trends and apparent temperature. We evaluated the cumulative relative risk of the added wave effect on mortality on lag days 0-30. The models were constructed using nine definitions of heat wave and two relationships (cubic spline and linear threshold model) between temperature and mortality to leave out the high temperature effect. Further, we performed sensitivity analysis to evaluate the changes in the effect of heat wave on mortality according to the different degrees of freedom for time trend and cubic spline of temperature. We found that heat wave had the added effect from the prolonged period of high temperature on mortality and it was considerable in the aspect of cumulative risk because of the lagged influence. When heat wave was defined with a threshold of 98th percentile temperature and ≥2, 3, and 4 consecutive days, mortality increased by 14.8 % (7.5-22.6, 95 % confidence interval (CI)), 18.1 % (10.8-26.0, 95 % CI), 18.1 % (10.7-25.9, 95 % CI), respectively, in cubic spline model. When it came to the definitions of 90th and 95th percentile, the risk increase in mortality declined to 3.7-5.8 % and 8.6-11.3 %, respectively. This effect was robust to the flexibility of the model for temperature and time trend, while the definitions of a heat wave were critical in estimating its relationship with mortality. This finding could help deepen our understanding and quantifying of the relationship between heat wave and mortality and select an appropriate definition of heat wave and temperature model in the future studies.

Affect of Brush Seals on Wave Rotor Performance Assessed

NASA Technical Reports Server (NTRS)

1995-01-01

The NASA Lewis Research Center's experimental and theoretical research shows that wave rotor topping can significantly enhance gas turbine engine performance levels. Engine-specific fuel consumption and specific power are potentially enhanced by 15 and 20 percent, respectively, in small (e.g., 400 to 700 hp) and intermediate (e.g., 3000 to 5000 hp) turboshaft engines. Furthermore, there is potential for a 3- to 6-percent specific fuel consumption enhancement in large (e.g., 80,000 to 100,000 lbf) turbofan engines. This wave-rotor-enhanced engine performance is accomplished within current material-limited temperature constraints. The completed first phase of experimental testing involved a three-port wave rotor cycle in which medium total pressure inlet air was divided into two outlet streams, one of higher total pressure and one of lower total pressure. The experiment successfully provided the data needed to characterize viscous, partial admission, and leakage loss mechanisms. Statistical analysis indicated that wave rotor product efficiency decreases linearly with the rotor to end-wall gap, the square of the friction factor, and the square of the passage of nondimensional opening time. Brush seals were installed to further minimize rotor passage-to-cavity leakage. The graph shows the effect of brush seals on wave rotor product efficiency. For the second-phase experiment, which involves a four-port wave rotor cycle in which heat is added to the Brayton cycle in an external burner, a one-dimensional design/analysis code is used in conjunction with a wave rotor performance optimization scheme and a two-dimensional Navier-Stokes code. The purpose of the four-port experiment is to demonstrate and validate the numerically predicted four-port pressure ratio versus temperature ratio at pressures and temperatures lower than those that would be encountered in a future wave rotor/demonstrator engine test. Lewis and the Allison Engine Company are collaborating to investigate wave rotor integration in an existing turboshaft engine. Recent theoretical efforts include simulating wave rotor dynamics (e.g., startup and load-change transient analysis), modifying the one-dimensional wave rotor code to simulate combustion internal to the wave rotor, and developing an analytical wave rotor design/analysis tool based on macroscopic balances for parametric wave rotor/engine analysis.

Characterization Test Report for the Mnemonics-UCS Wireless Surface Acoustic Wave Sensor System

NASA Technical Reports Server (NTRS)

Duncan, Joshua J.; Youngquist, Robert C.

2013-01-01

The scope of this testing includes the Surface Acoustic Wave Sensor System delivered to KSC: two interrogator (transceiver) systems, four temperature sensors, with wooden mounting blocks, two antennas, two power supplies, network cables, and analysis software. Also included are a number of additional temperature sensors and newly-developed hydrogen sensors

Correlations between wave activity and electron temperature in the Martian upper ionosphere

NASA Astrophysics Data System (ADS)

Fowler, Chris; Andersson, Laila; Ergun, Robert; Andrews, David

2017-04-01

Prior to the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission, only two electron temperature profiles of the Martian ionosphere existed, made by the Viking landers in the late 70s. Since MAVENs arrival at Mars in late 2014, electron temperature (and density) profiles have been measured every orbit, once every 4.5 hours. Recent analysis of this new dataset has shown that the Martian ionospheric electron temperature is significantly warmer than expected by factors of 2-3 above the exobase and within the upper ionosphere. We present correlations between electron temperature and electric field wave power (also measured by MAVEN), and discuss the possibility that such waves (which are likely produced by the Mars-solar wind interaction) may drive electron heating and contribute to the observed high temperatures.

Status of MTP Data Analysis for TCSP

NASA Technical Reports Server (NTRS)

Mahoney, Michael J.

2006-01-01

Topics covered include: a) MTP temperature calibration and data analysis; b) Background for interpreting MTP data; c) Large amplitude temperature structure; d) Gravity waves (GWs) in MTP data; and e) Subsidence over hurricanes.

On the instability of a liquid sheet moving in vacuum

NASA Astrophysics Data System (ADS)

Sisoev, G. M.; Osiptsov, A. N.; Koroteev, A. A.

2018-03-01

A linear stability analysis of a non-isothermal liquid sheet moving in vacuum is studied taking into account the temperature dependencies of the liquid viscosity, thermal conductivity, and surface tension coefficients. It is found that there are two mechanisms of instability. The short-wave instability is caused by viscosity stratification across the sheet due to nonuniform temperature profiles developed downstream in the cooling sheet. The long-wave thermocapillary instability is caused by the temperature gradient along the sheet surfaces. Computed examples of steady flows and their instabilities demonstrated that the unstable short waves have much larger amplification factors.

Statistical comparisons of gravity wave features derived from OH airglow and SABER data

NASA Astrophysics Data System (ADS)

Gelinas, L. J.; Hecht, J. H.; Walterscheid, R. L.

2017-12-01

The Aerospace Corporation's near-IR camera (ANI), deployed at Andes Lidar Observatory (ALO), Cerro Pachon Chile (30S,70W) since 2010, images the bright OH Meinel (4,2) airglow band. The imager provides detailed observations of gravity waves and instability dynamics, as described by Hecht et al. (2014). The camera employs a wide-angle lens that views a 73 by 73 degree region of the sky, approximately 120 km x 120 km at 85 km altitude. Image cadence of 30s allows for detailed spectral analysis of the horizontal components of wave features, including the evolution and decay of instability features. The SABER instrument on NASA's TIMED spacecraft provides remote soundings of kinetic temperature profiles from the lower stratosphere to the lower thermosphere. Horizontal and vertical filtering techniques allow SABER temperatures to be analyzed for gravity wave variances [Walterscheid and Christensen, 2016]. Here we compare the statistical characteristics of horizontal wave spectra, derived from airglow imagery, with vertical wave variances derived from SABER temperature profiles. The analysis is performed for a period of strong mountain wave activity over the Andes spanning the period between June and September 2012. Hecht, J. H., et al. (2014), The life cycle of instability features measured from the Andes Lidar Observatory over Cerro Pachon on March 24, 2012, J. Geophys. Res. Atmos., 119, 8872-8898, doi:10.1002/2014JD021726. Walterscheid, R. L., and A. B. Christensen (2016), Low-latitude gravity wave variances in the mesosphere and lower thermosphere derived from SABER temperature observation and compared with model simulation of waves generated by deep tropical convection, J. Geophys. Res. Atmos., 121, 11,900-11,912, doi:10.1002/2016JD024843.

On the instability and energy flux of lower hybrid waves in the Venus plasma mantle

NASA Technical Reports Server (NTRS)

Strangeway, R. J.; Crawford, G. K.

1993-01-01

Waves generated near the lower hybrid resonance frequency by the modified two stream instability have been invoked as a possible source of energy flux into the topside ionosphere of Venus. These waves are observed above the ionopause in a region known as the plasma mantle. The plasma within the mantle appears to be a mixture of magnetosheath and ionospheric plasmas. Since the magnetosheath electrons and ions have temperatures of several tens of eV, any instability analysis of the modified two stream instability requires the inclusion of finite electron and ion temperatures. Finite temperature effects are likely to reduce the growth rate of the instability. Furthermore, the lower hybrid waves are only quasi-electrostatic, and the energy flux of the waves is mainly carried by parallel Poynting flux. The magnetic field in the mantle is draped over the ionopause. Lower hybrid waves therefore cannot transport any significant wave energy to lower altitudes, and so do not act as a source of additional heat to the topside ionosphere.

Analysis of wave-like oscillations in parameters of sporadic E layer and neutral atmosphere

NASA Astrophysics Data System (ADS)

Mošna, Z.; Koucká Knížová, P.

2012-12-01

The present study mainly concerns the wave-like activity in the ionospheric sporadic E layer (Es) and in the lower lying stratosphere. The proposed analysis involves parameters describing the state of plasma in the sporadic E layer. Critical frequencies foEs and layer heights hEs were measured at the Pruhonice station (50°N, 14.5°E) during summer campaigns 2004, 2006 and 2008. Further, we use neutral atmosphere (temperature data at 10 hPa) data from the same time interval. The analysis concentrates on vertically propagating wave-like structures within distant atmospheric regions. By means of continuous wavelet transform (CWT) we have detected significant wave-like oscillation at periods covering tidal and planetary oscillation domains both in the Es layer parameters (some of them were reported earlier, for instance in works of Abdu et al., 2003; Pancheva and Mitchel, 2004; Pancheva et al., 2003; Šauli and Bourdillon, 2008) and in stratospheric temperature variations. Further analyses using cross wavelet transform (XWT) and wavelet coherence analysis (WTC) show that despite high wave-like activity in a wide period range, there are only limited coherent wave-like bursts present in both spectra. Such common coherent wave bursts occur on periods close to eigen-periods of the terrestrial atmosphere. We suppose that vertical coupling between atmospheric regions realized by vertically propagating planetary waves occurs predominantly on periods close to those of Rossby modes. Analysis of the phase shift between data from distant atmospheric regions reveals high variability and very likely supports the non-linear scenario of the vertical coupling provided by planetary waves.

Shock wave structure in rarefied polyatomic gases with large relaxation time for the dynamic pressure

NASA Astrophysics Data System (ADS)

Taniguchi, Shigeru; Arima, Takashi; Ruggeri, Tommaso; Sugiyama, Masaru

2018-05-01

The shock wave structure in rarefied polyatomic gases is analyzed based on extended thermodynamics (ET). In particular, the case with large relaxation time for the dynamic pressure, which corresponds to large bulk viscosity, is considered by adopting the simplest version of extended thermodynamics with only 6 independent fields (ET6); the mass density, the velocity, the temperature and the dynamic pressure. Recently, the validity of the theoretical predictions by ET was confirmed by the numerical analysis based on the kinetic theory in [S Kosuge and K Aoki: Phys. Rev. Fluids, Vol. 3, 023401 (2018)]. It was shown that numerical results using the polyatomic version of ellipsoidal statistical model agree with the theoretical predictions by ET for small or moderately large Mach numbers. In the present paper, first, we compare the theoretical predictions by ET6 with the ones by kinetic theory for large Mach number under the same assumptions, that is, the gas is polytropic and the bulk viscosity is proportional to the temperature. Second, the shock wave structure for large Mach number in a non-polytropic gas is analyzed with the particular interest in the effect of the temperature dependence of specific heat and the bulk viscosity on the shock wave structure. Through the analysis of the case of a rarefied carbon dioxide (CO2) gas, it is shown that these temperature dependences play important roles in the precise analysis of the structure for strong shock waves.

Multitude of core-localized shear Alfvén waves in a high-temperature fusion plasma.

PubMed

Nazikian, R; Berk, H L; Budny, R V; Burrell, K H; Doyle, E J; Fonck, R J; Gorelenkov, N N; Holcomb, C; Kramer, G J; Jayakumar, R J; La Haye, R J; McKee, G R; Makowski, M A; Peebles, W A; Rhodes, T L; Solomon, W M; Strait, E J; Vanzeeland, M A; Zeng, L

2006-03-17

Evidence is presented for a multitude of discrete frequency Alfvén waves in the core of magnetically confined high-temperature fusion plasmas. Multiple diagnostic instruments confirm wave excitation over a wide spatial range from the device size at the longest wavelengths down to the thermal ion Larmor radius. At the shortest scales, the poloidal wavelengths are comparable to the scale length of electrostatic drift wave turbulence. Theoretical analysis confirms a dominant interaction of the modes with particles in the thermal ion distribution traveling well below the Alfvén velocity.

Changes in heat waves indices in Romania over the period 1961-2015

NASA Astrophysics Data System (ADS)

Croitoru, Adina-Eliza; Piticar, Adrian; Ciupertea, Antoniu-Flavius; Roşca, Cristina Florina

2016-11-01

In the last two decades many climate change studies have focused on extreme temperatures as they have a significant impact on environment and society. Among the weather events generated by extreme temperatures, heat waves are some of the most harmful. The main objective of this study was to detect and analyze changes in heat waves in Romania based on daily observation data (maximum and minimum temperature) over the extended summer period (May-Sept) using a set of 10 indices and to explore the spatial patterns of changes. Heat wave data series were derived from daily maximum and minimum temperature data sets recorded in 29 weather stations across Romania over a 55-year period (1961-2015). In this study, the threshold chosen was the 90th percentile calculated based on a 15-day window centered on each calendar day, and for three baseline periods (1961-1990, 1971-2000, and 1981-2010). Two heat wave definitions were considered: at least three consecutive days when maximum temperature exceeds 90th percentile, and at least three consecutive days when minimum temperature exceeds 90th percentile. For each of them, five variables were calculated: amplitude, magnitude, number of events, duration, and frequency. Finally, 10 indices resulted for further analysis. The main results are: most of the indices have statistically significant increasing trends; only one index for one weather station indicated statistically significant decreasing trend; the changes are more intense in case of heat waves detected based on maximum temperature compared to those obtained for heat waves identified based on minimum temperature; western and central regions of Romania are the most exposed to increasing heat waves.

Long-Term Global Morphology of Gravity Wave Activity Using UARS Data

NASA Technical Reports Server (NTRS)

Eckermann, Stephen D.; Bacmeister, Julio T.; Wu, Dong L.

1998-01-01

This is the first quarter's report on research to extract global gravity-wave data from satellite data and to model those observations synoptically. Preliminary analysis of global maps of extracted middle atmospheric temperature variance from the CRISTA instrument is presented, which appear to contain gravity-wave information. Corresponding simulations of global gravity-wave and mountain-wave activity during this mission period are described using global ray-tracing and mountain-wave models, and interesting similarities among simulated data and CRISTA data are noted. Climatological simulations of mesospheric gravity-wave activity using the HWM-03 wind-temperature climatology are also reported, for comparison with UARS MLS data. Preparatory work on modeling of gravity wave observations from space-based platforms and subsequent interpretation of the MLS gravity-wave product are also described. Preliminary interpretation and relation to the research objectives are provided, and further action for the next quarter's research is recommended.

Heat, heat waves, and out-of-hospital cardiac arrest.

PubMed

Kang, Si-Hyuck; Oh, Il-Young; Heo, Jongbae; Lee, Hyewon; Kim, Jungeun; Lim, Woo-Hyun; Cho, Youngjin; Choi, Eue-Keun; Yi, Seung-Muk; Sang, Do Shin; Kim, Ho; Youn, Tae-Jin; Chae, In-Ho; Oh, Seil

2016-10-15

Cardiac arrest is one of the common presentations of cardiovascular disorders and a leading cause of death. There are limited data on the relationship between out-of-hospital cardiac arrest (OHCA) and ambient temperatures, specifically extreme heat. This study investigated how heat and heat waves affect the occurrence of OHCA. Seven major cities in Korea with more than 1 million residents were included in this study. A heat wave was defined as a daily mean temperature above the 98th percentile of the yearly distribution for at least two consecutive days. A total of 50,318 OHCAs of presumed cardiac origin were identified from the nationwide emergency medical service database between 2006 and 2013. Ambient temperature and OHCA had a J-shaped relationship with a trough at 28°C. Heat waves were shown to be associated with a 14-% increase in the risk of OHCA. Adverse effects were apparent from the beginning of each heat wave period and slightly increased during its continuation. Excess OHCA events during heat waves occurred between 3PM and 5PM. Subgroup analysis showed that those 65years or older were significantly more susceptible to heat waves. Ambient temperature and OHCA had a J-shaped relationship. The risk of OHCA was significantly increased with heat waves. Excess OHCA events primarily occurred during the afternoon when the temperature was high. We found that the elderly were more susceptible to the deleterious effects of heat waves. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Satellite radio occultation investigations of internal gravity waves in the planetary atmospheres

NASA Astrophysics Data System (ADS)

Kirillovich, Ivan; Gubenko, Vladimir; Pavelyev, Alexander

Internal gravity waves (IGWs) modulate the structure and circulation of the Earth’s atmosphere, producing quasi-periodic variations in the wind velocity, temperature and density. Similar effects are anticipated for the Venus and Mars since IGWs are a characteristic of stably stratified atmosphere. In this context, an original method for the determination of IGW parameters from a vertical temperature profile measurement in a planetary atmosphere has been developed [Gubenko et al., 2008, 2011, 2012]. This method does not require any additional information not contained in the profile and may be used for the analysis of profiles measured by various techniques. The criterion for the IGW identification has been formulated and argued. In the case when this criterion is satisfied, the analyzed temperature fluctuations can be considered as wave-induced. The method is based on the analysis of relative amplitudes of the wave field and on the linear IGW saturation theory in which these amplitudes are restricted by dynamical (shear) instability processes in the atmosphere. When the amplitude of an internal wave reaches the shear instability threshold, energy is assumed to be dissipated in such a way that the IGW amplitude is maintained at the instability threshold level as the wave propagates upwards. We have extended the developed technique [Gubenko et al., 2008] in order to reconstruct the complete set of wave characteristics including such important parameters as the wave kinetic and potential energy per unit mass and IGW fluxes of the energy and horizontal momentum [Gubenko et al., 2011]. We propose also an alternative method to estimate the relative amplitudes and to extract IGW parameters from an analysis of perturbations of the Brunt-Vaislala frequency squared [Gubenko et al., 2011]. An application of the developed method to the radio occultation (RO) temperature data has given the possibility to identify the IGWs in the Earth's, Martian and Venusian atmospheres and to determine the magnitudes of key wave parameters such as the intrinsic frequency, amplitudes of vertical and horizontal wind velocity perturbations, vertical and horizontal wavelengths, intrinsic vertical and horizontal phase (and group) speeds, kinetic and potential energy per unit mass, vertical fluxes of the wave energy and horizontal momentum. Vertical profiles of temperature retrieved from RO measurements of the CHAMP (Earth), Mars Global Surveyor (Mars), Magellan and Venus Express (Venus) missions are used and analyzed to identify discrete or “narrow spectral” wave events and to determine IGW characteristics in the Earth’s, Martian and Venusian atmospheres. This work was partially supported by the RFBR grant 13-02-00526-a and Program 22 of the RAS Presidium. References. Gubenko V.N., Pavelyev A.G., Andreev V.E. Determination of the intrinsic frequency and other wave parameters from a single vertical temperature or density profile measurement // J. Geophys. Res. 2008. V. 113. No.D08109, doi:10.1029/2007JD008920. Gubenko V.N., Pavelyev A.G., Salimzyanov R.R., Pavelyev A.A. Reconstruction of internal gravity wave parameters from radio occultation retrievals of vertical temperature profiles in the Earth’s atmosphere // Atmos. Meas. Tech. 2011. V. 4. No.10. P. 2153-2162, doi:10.5194/amt-4-2153-2011. Gubenko V.N., Pavelyev A.G., Salimzyanov R.R., Andreev V.E. A method for determination of internal gravity wave parameters from a vertical temperature or density profile measurement in the Earth’s atmosphere // Cosmic Res. 2012. V. 50. No.1. P. 21-31, doi: 10.1134/S0010952512010029.

The Effect of Background Plasma Temperature on Growth and Damping of Whistler Mode Wave Power in the Earth's Magnetosphere

NASA Astrophysics Data System (ADS)

Maxworth, A. S.; Golkowski, M.; Malaspina, D.; Jaynes, A. N.

2017-12-01

Whistler mode waves play a dominant role in the energy dynamics of the Earth's magnetosphere. Trajectory of whistler mode waves can be predicted by raytracing. Raytracing is a numerical method which solves the Haselgrove's equations at each time step taking the background plasma parameters in to account. The majority of previous raytracing work was conducted assuming a cold (0 K) background magnetospheric plasma. Here we perform raytracing in a finite temperature plasma with background electron and ion temperatures of a few eV. When encountered with a high energy (>10 keV) electron distribution, whistler mode waves can undergo a power attenuation and/or growth, depending on resonance conditions which are a function of wave frequency, wave normal angle and particle energy. In this work we present the wave power attenuation and growth analysis of whistler mode waves, during the interaction with a high energy electron distribution. We have numerically modelled the high energy electron distribution as an isotropic velocity distribution, as well as an anisotropic bi-Maxwellian distribution. Both cases were analyzed with and without the temperature effects for the background magnetospheric plasma. Finally we compare our results with the whistler mode energy distribution obtained by the EMFISIS instrument hosted at the Van Allen Probe spacecraft.

Simultaneous measurement of temperature and emissivity of lunar regolith simulant using dual-channel millimeter-wave radiometry.

PubMed

McCloy, J S; Sundaram, S K; Matyas, J; Woskov, P P

2011-05-01

Millimeter wave (MMW) radiometry can be used for simultaneous measurement of emissivity and temperature of materials under extreme environments (high temperature, pressure, and corrosive environments). The state-of-the-art dual channel MMW passive radiometer with active interferometric capabilities at 137 GHz described here allows for radiometric measurements of sample temperature and emissivity up to at least 1600 °C with simultaneous measurement of sample surface dynamics. These capabilities have been used to demonstrate dynamic measurement of melting of powders of simulated lunar regolith and static measurement of emissivity of solid samples. The paper presents the theoretical background and basis for the dual-receiver system, describes the hardware in detail, and demonstrates the data analysis. Post-experiment analysis of emissivity versus temperature allows further extraction from the radiometric data of millimeter wave viewing beam coupling factors, which provide corroboratory evidence to the interferometric data of the process dynamics observed. These results show the promise of the MMW system for extracting quantitative and qualitative process parameters for industrial processes and access to real-time dynamics of materials behavior in extreme environments.

Multi-frequency ICRF diagnostic of Tokamak plasmas

NASA Astrophysics Data System (ADS)

Lafonteese, David James

This thesis explores the diagnostic possibilities of a fast wave-based method for measuring the ion density and temperature profiles of tokamak plasmas. In these studies fast waves are coupled to the plasma at frequencies at the second harmonic of the ion gyrofrequency, at which wave energy is absorbed by the finite-temperature ions. As the ion gyrofrequency is dependent upon the local magnetic field, which varies as l/R in a tokamak, this power absorption is radially localized. The simultaneous launching of multiple frequencies, all resonating at different plasma positions, allows local measurements of the ion density and temperature. To investigate the profile applications of wave damping measurements in a simulated tokamak, an inhouse slab-model ICRF code is developed. A variety of analysis methods are presented, and ion density and temperature profiles are reconstructed for hydrogen plasmas for the Electric Tokamak (ET) and ITER parameter spaces. These methods achieve promising results in simulated plasmas featuring bulk ion heating, off-axis RF heating, and density ramps. The experimental results of similar studies on the Electric Tokamak, a high aspect ratio (R/a = 5), low toroidal field (2.2 kG) device are then presented. In these studies, six fast wave frequencies were coupled using a single-strap, low-field-side antenna to ET plasmas. The frequencies were variable, and could be tuned to resonate at different radii for different experiments. Four magnetic pickup loops were used to measure of the toroidal component of the wave magnetic field. The expected greater eigenmode damping of center-resonant frequencies versus edge-resonant frequencies is consistently observed. Comparison of measured aspects of fast wave behavior in ET is made with the slab code predictions, which validate the code simulations under weakly-damped conditions. A density profile is measured for an ET discharge through analysis of the fast wave measurements, and is compared to an electron density profile derived from Thomson scattering data. The methodology behind a similar measurement of the ion temperature profile is also presented.

A Self-consistent Model of the Coronal Heating and Solar Wind Acceleration Including Compressible and Incompressible Heating Processes

NASA Astrophysics Data System (ADS)

Shoda, Munehito; Yokoyama, Takaaki; Suzuki, Takeru K.

2018-02-01

We propose a novel one-dimensional model that includes both shock and turbulence heating and qualify how these processes contribute to heating the corona and driving the solar wind. Compressible MHD simulations allow us to automatically consider shock formation and dissipation, while turbulent dissipation is modeled via a one-point closure based on Alfvén wave turbulence. Numerical simulations were conducted with different photospheric perpendicular correlation lengths {λ }0, which is a critical parameter of Alfvén wave turbulence, and different root-mean-square photospheric transverse-wave amplitudes δ {v}0. For the various {λ }0, we obtain a low-temperature chromosphere, high-temperature corona, and supersonic solar wind. Our analysis shows that turbulence heating is always dominant when {λ }0≲ 1 {Mm}. This result does not mean that we can ignore the compressibility because the analysis indicates that the compressible waves and their associated density fluctuations enhance the Alfvén wave reflection and therefore the turbulence heating. The density fluctuation and the cross-helicity are strongly affected by {λ }0, while the coronal temperature and mass-loss rate depend weakly on {λ }0.

Sub-seasonal temperature variability in the tropical upper troposphere and lower stratosphere observed with GPS radio occultation

NASA Astrophysics Data System (ADS)

Scherllin-Pirscher, Barbara; Randel, William J.; Kim, Joowan

2017-04-01

We investigate sub-seasonal temperature variability in the tropical upper troposphere and lower stratosphere (UTLS) region using daily gridded fields of GPS radio occultation measurements. The unprecedented vertical resolution (from about 100 m in the troposphere to about 1.5 km in the stratosphere) and high accuracy and precision (0.7 K to 1 K between 8 km and 25 km) make these data ideal for characterizing temperature oscillations with short vertical wavelengths. Long-term behavior of sub-seasonal temperature variability is investigated using the entire RO record from January 2002 to December 2014 (13 years of data). Transient sub-seasonal waves including eastward-propagating Kelvin waves (isolated with space-time spectral analysis) dominate large-scale zonal temperature variability in the tropical tropopause region and in the lower stratosphere. Above 20 km, Kelvin waves are strongly modulated by the quasi-biennial oscillation (QBO). Enhanced wave activity can be found during the westerly shear phase of the QBO. In the tropical tropopause region, however, sub-seasonal waves are highly transient in time. Several peaks of Kelvin-wave activity coincide with short-term fluctuations in tropospheric deep convection, but other episodes are not evidently related. Also, there are no obvious relationships with zonal winds or stability fields near the tropical tropopause. Further investigations of convective forcing and atmospheric background conditions along the waves' trajectories are needed to better understand sub-seasonal temperature variability near the tropopause. For more details, see Scherllin-Pirscher, B., Randel, W. J., and Kim, J.: Tropical temperature variability and Kelvin-wave activity in the UTLS from GPS RO measurements, Atmos. Chem. Phys., 17, 793-806, doi:10.5194/acp-17-793-2017, 2017. http://www.atmos-chem-phys.net/17/793/2017/acp-17-793-2017.html

Reconstruction of the temperature field for inverse ultrasound hyperthermia calculations at a muscle/bone interface.

PubMed

Liauh, Chihng-Tsung; Shih, Tzu-Ching; Huang, Huang-Wen; Lin, Win-Li

2004-02-01

An inverse algorithm with Tikhonov regularization of order zero has been used to estimate the intensity ratios of the reflected longitudinal wave to the incident longitudinal wave and that of the refracted shear wave to the total transmitted wave into bone in calculating the absorbed power field and then to reconstruct the temperature distribution in muscle and bone regions based on a limited number of temperature measurements during simulated ultrasound hyperthermia. The effects of the number of temperature sensors are investigated, as is the amount of noise superimposed on the temperature measurements, and the effects of the optimal sensor location on the performance of the inverse algorithm. Results show that noisy input data degrades the performance of this inverse algorithm, especially when the number of temperature sensors is small. Results are also presented demonstrating an improvement in the accuracy of the temperature estimates by employing an optimal value of the regularization parameter. Based on the analysis of singular-value decomposition, the optimal sensor position in a case utilizing only one temperature sensor can be determined to make the inverse algorithm converge to the true solution.

Performance of Gas Turbine Engines Using Wave Rotors Modeled

NASA Technical Reports Server (NTRS)

1997-01-01

A wave rotor is a device that can boost the pressure and temperature of an airflow. When used as part of the core of a gas turbine engine, a wave rotor can significantly improve the thrust or shaft horsepower by boosting the flow pressure without raising the turbine inlet temperature. The NASA Lewis Research Center's Aeropropulsion Analysis Office, which is identifying technologies and research opportunities that will enhance the technical and economic competitiveness of the U.S. aeronautics industry, is evaluating the wave rotor to quantify the potential benefits of this device. Preliminary studies such as these are critical to identifying technologies that have high payoffs.

Linking North American Summer Ozone Pollution Episodes to Subseasonal Atmospheric Variability

NASA Astrophysics Data System (ADS)

White, E. C.; Watt-Meyer, O.; Kushner, P. J.; Jones, D. B. A.

2017-12-01

Ozone concentrations in the planetary boundary layer (PBL) are positively correlated with surface air temperature due to shared influences including incident solar radiation and PBL stagnancy, as well as the temperature-sensitive emission of ozone precursor compounds. While previous studies have linked heat waves in North America to modes of subseasonal atmospheric variability, such analyses have not been applied to summertime ozone pollution episodes. This study investigates a possible link between subseasonal atmospheric variability in reanalysis data and summertime ozone pollution episodes identified in almost thirty years of in-situ measurements from the Air Quality System (AQS) network in the United States. AQS stations are grouped into regions likely to experience simultaneous extreme ozone concentrations using statistical clustering methods. Composite meteorological patterns are calculated for ozone episodes in each of these regions. The same analysis is applied to heat waves identified in AQS temperature records for comparison. Local meteorological features during typical ozone episodes include extreme temperatures and reduced cloud cover related to anomalous synoptic-scale anticyclonic circulation aloft. These anticyclonic anomalies are typically embedded in wave trains extending from the North Pacific to North Atlantic. Spectral analysis of these wave trains reveals that low-frequency standing waves play a prominent role. These long-lived circulation patterns may provide a means to increase air quality prediction lead-times and to estimate the frequency of ozone pollution episodes under climate change.

Space-based measurements of stratospheric mountain waves by CRISTA 1. Sensitivity, analysis method, and a case study

NASA Astrophysics Data System (ADS)

Preusse, Peter; Dörnbrack, Andreas; Eckermann, Stephen D.; Riese, Martin; Schaeler, Bernd; Bacmeister, Julio T.; Broutman, Dave; Grossmann, Klaus U.

2002-09-01

The Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) instrument measured stratospheric temperatures and trace species concentrations with high precision and spatial resolution during two missions. The measuring technique is infrared limb-sounding of optically thin emissions. In a general approach, we investigate the applicability of the technique to measure gravity waves (GWs) in the retrieved temperature data. It is shown that GWs with wavelengths of the order of 100-200 km horizontally can be detected. The results are applicable to any instrument using the same technique. We discuss additional constraints inherent to the CRISTA instrument. The vertical field of view and the influence of the sampling and retrieval imply that waves with vertical wavelengths ~3-5 km or larger can be retrieved. Global distributions of GW fluctuations were extracted from temperature data measured by CRISTA using Maximum Entropy Method (MEM) and Harmonic Analysis (HA), yielding height profiles of vertical wavelength and peak amplitude for fluctuations in each scanned profile. The method is discussed and compared to Fourier transform analyses and standard deviations. Analysis of data from the first mission reveals large GW amplitudes in the stratosphere over southernmost South America. These waves obey the dispersion relation for linear two-dimensional mountain waves (MWs). The horizontal structure on 6 November 1994 is compared to temperature fields calculated by the Pennsylvania State University (PSU)/National Center for Atmospheric Research (NCAR) mesoscale model (MM5). It is demonstrated that precise knowledge of the instrument's sensitivity is essential. Particularly good agreement is found at the southern tip of South America where the MM5 accurately reproduces the amplitudes and phases of a large-scale wave with 400 km horizontal wavelength. Targeted ray-tracing simulations allow us to interpret some of the observed wave features. A companion paper will discuss MWs on a global scale and estimates the fraction that MWs contribute to the total GW energy (Preusse et al., in preparation, 2002).

Kinematic dust viscosity effect on linear and nonlinear dust-acoustic waves in space dusty plasmas with nonthermal ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

El-Hanbaly, A. M.; Sallah, M., E-mail: msallahd@mans.edu.eg; El-Shewy, E. K.

2015-10-15

Linear and nonlinear dust-acoustic (DA) waves are studied in a collisionless, unmagnetized and dissipative dusty plasma consisting of negatively charged dust grains, Boltzmann-distributed electrons, and nonthermal ions. The normal mode analysis is used to obtain a linear dispersion relation illustrating the dependence of the wave damping rate on the carrier wave number, the dust viscosity coefficient, the ratio of the ion temperature to the electron temperatures, and the nonthermal parameter. The plasma system is analyzed nonlinearly via the reductive perturbation method that gives the KdV-Burgers equation. Some interesting physical solutions are obtained to study the nonlinear waves. These solutions aremore » related to soliton, a combination between a shock and a soliton, and monotonic and oscillatory shock waves. Their behaviors are illustrated and shown graphically. The characteristics of the DA solitary and shock waves are significantly modified by the presence of nonthermal (fast) ions, the ratio of the ion temperature to the electron temperature, and the dust kinematic viscosity. The topology of the phase portrait and the potential diagram of the KdV-Burgers equation is illustrated, whose advantage is the ability to predict different classes of traveling wave solutions according to different phase orbits. The energy of the soliton wave and the electric field are calculated. The results in this paper can be generalized to analyze the nature of plasma waves in both space and laboratory plasma systems.« less

[Impact of daily mean temperature, cold spells, and heat waves on stroke mortality a multivariable Meta-analysis from 12 counties of Hubei province, China].

PubMed

Zhang, Y Q; Yu, C H; Bao, J Z

2017-04-10

Objective: To assess the acute effects of daily mean temperature, cold spells, and heat waves on stroke mortality in 12 counties across Hubei province, China. Methods: Data related to daily mortality from stroke and meteorology in 12 counties across Hubei province during 2009-2012, were gathered. Distributed lag nonlinear model (DLNM) was first used, to estimate the county-specific associations between daily mean temperature, cold spells, heat waves and stroke mortality. Multivariate Meta-analysis was then applied to pool the community-specific relationships between temperature and stroke mortality (exposure-response relationship) as well as both cold- and- heat-associated risks on mortality at different lag days (lag-response relationship). Results: During 2009-2012, a total population of 6.7 million was included in this study with 42 739 persons died of stroke. An average of 2.7 (from 0.5 to 6.0) stroke deaths occurred daily in each county, with annual average mean temperature as 16.6 ℃ (from 14.7 ℃ to 17.4 ℃) during the study period. An inverse J-shaped association between temperature and stroke mortality was observed at the provincial level. Pooled mortality effect of cold spells showed a 2-3-day delay and lasted about 10 days, while effect of heat waves appeared acute but attenuated within a few days. The mortality risks on cold-spell days ranged from 0.968 to 1.523 in 12 counties at lag 3-14, with pooled effect as 1.180 (95 %CI: 1.043-1.336). The pooled mortality risk (ranged from 0.675 to 2.066) on heat-wave days at lag 0-2 was 1.114 (95 %CI: 1.012-1.227). Conclusions: An inverse J-shaped association between temperature and stroke mortality was observed in Hubei province, China. Both cold spells and heat waves were associated with increased stroke mortality, while different lag patterns were observed in the mortality effects of heat waves and cold spells.

Frequency and Thermal Behavior of Acoustic Absorption in ɛ-GaSe Crystals

NASA Astrophysics Data System (ADS)

Dzhafarova, S. Z.

2018-04-01

The paper presents results of measuring acoustic absorption in ɛ-GaSe crystals. The absorption of a longitudinal wave which propagates normal to the crystal layers, quadratically depends on frequency. However, it does not depend on temperature, i.e. it displays an Akhiezer behavior although its absolute value considerably exceeds the expected. The analysis of the frequency and thermal behavior of absorption of piezoelectric waves propagating along the layers, includes the deduction of contribution made by the interaction between waves and charge carriers. This analysis shows the linear dependence between the lattice absorption of these waves and the frequency. The linear frequency and weak temperature dependences of the acoustic absorption characterize the additional ultra-Akhiezer absorption in glasses. In our case, it can be caused by various polytypes forming in GaSe crystals which differ merely in a mutual arrangement of layers.

Electromagnetic ion cyclotron waves in the plasma depletion layer

NASA Technical Reports Server (NTRS)

Denton, Richard E.; Hudson, Mary K.; Fuselier, Stephen A.; Anderson, Brian J.

1993-01-01

Results of a study of the theoretical properties of electromagnetic ion cyclotron (EMIC) waves which occur in the plasma depletion layer are presented. The analysis assumes a homogeneous plasma with the characteristics which were measured by the AMPTE/CCE satellite at 1450-1501 UT on October 5, 1984. Waves were observed in the Pc 1 frequency range below the hydrogen gyrofrequency, and these waves are identified as EMIC waves. The higher-frequency instability is driven by the temperature anisotropy of the H(+) ions, while the lower-frequency instability is driven by the temperature anisotropy of the He(2+) ions. It is argued that the higher-frequency waves will have k roughly parallel to B(0) and will be left-hand polarized, while the lower frequency wave band will have k oblique to B(0) and will be linearly polarized, in agreement with observations.

Long-Term Global Morphology of Gravity Wave Activity Using UARS Data

NASA Technical Reports Server (NTRS)

Eckermann, Stephen D.; Jackman, Charles H. (Technical Monitor)

2000-01-01

This report provides a broad outline of the total body of research conducted during the past three years. We report on detailed model studies of the precise way in which infrared limb scanning satellites explicitly detect gravity waves, and use these insights to resolve earlier discrepant zonal mean estimates of gravity wave variances from satellite limb scanners. Detailed analysis of CRISTA temperature fluctuations are outlined, which provide new global information on long-wavelength stratospheric gravity waves generated by mountains, tropical convection and the mid-latitude jet stream- vortex system, as well as interactions higher in the mesosphere with the diurnal tide. The detailed insights gained from analyzing CRISTA data are applied to provide a multi- year analysis of stratospheric mountain waves over the Andes evident in MLS limb-track data. We also demonstrate for the first time that stratospheric temperature data from the CLAES instrument on UARS resolved gravity waves, and we highlight mountain wave information in a subset of these data. Final conclusions and recommendations are set forth, and the present findings are directly related to the original goals of the research contract. A full list of publications that resulted from this research is provided.

Long-Term Global Morphology of Gravity Wave Activity Using UARS Data

NASA Technical Reports Server (NTRS)

Eckermann, Stephen D.

2000-01-01

This report provides a broad outline of the total body of research conducted during the past three years. We report on detailed model studies of the precise way in which infrared limb scanning satellites explicitly detect gravity waves, and use these insights to resolve earlier discrepant zonal mean estimates of gravity wave variances from satellite limb scanners. Detailed analysis of CRISTA temperature fluctuations are outlined, which provide new global information on long-wavelength stratospheric gravity waves generated by mountains, tropical convection and the mid-latitude jet stream-vortex system, as well as interactions higher in the mesosphere with the diurnal tide. The detailed insights gained from analyzing CRISTA data are applied to provide a multiyear analysis of stratospheric mountain waves over the Andes evident in MLS limb-track data. We also demonstrate for the first time that stratospheric temperature data from the CLAES instrument on UARS resolved gravity waves, and we highlight mountain wave information in a subset of these data. Final conclusions and recommendations are set forth, and the present findings are directly related to the original goals of the research contract. A full list of publications that resulted from this research is provided.

Kelvin wave-induced trace constituent oscillations in the equatorial stratosphere

NASA Technical Reports Server (NTRS)

Randel, William J.

1990-01-01

Kelvin wave induced oscillations in ozone (O3), water vapor (H2O), nitric acid (HNO3) and nitrogen dioxide (NO2) in the equatorial stratosphere are analyzed using Limb Infrared Monitor of the Stratosphere (LIMS) data. Power and cross-spectrum analyses reveal coherent eastward propagating zonal wave 1 and 2 constituent fluctuations, due to the influence of Kelvin waves previously documented in the LIMS data. Comparison is made between a preliminary and the archival versions of the LIMS data; significant differences are found, demonstrating the sensitivity of constituent retrievals to derived temperature profiles. Because Kelvin waves have vanishing meridional velocity, analysis of tracer transport in the meridional plane is substantially simplified. Kelvin wave vertical advection is demonstrated by coherent, in-phase temperature-tracer oscillations, co-located near regions of strong background vertical gradients.

Effects of temperature and heat waves on emergency department visits and emergency ambulance dispatches in Pudong New Area, China: a time series analysis.

PubMed

Sun, Xiaoming; Sun, Qiao; Yang, Minjuan; Zhou, Xianfeng; Li, Xiaopan; Yu, Aiqing; Geng, Fuhai; Guo, Yuming

2014-10-02

In July 2013, an extended heat episode with extreme high temperature covered Pudong New Area, the largest district in Shanghai. The current study estimates the impacts of temperature and heat waves on emergency department visits (EDV) and emergency ambulance dispatches (EAD) using time-series approaches in Pudong, from 2011 to 2013. An over-dispersed Poisson generalized additive model was used to examine the association between temperature and EDV and EAD. Heat wave effects with different heat wave definitions considering both the intensity and durations were also estimated. Immediate effects of temperature on EDV and EAD were detected, after controlling for trends of time and day of week. The exposure-response relationships showed J-shaped curves with higher threshold temperature of EDV than that of EAD visually. When estimating risk changes on heat days compared with non-heat days using different percentiles of daily mean temperature in definition, EAD showed significant increases while non-significant or even negative associations were found for EDV. Heat wave with intensity above the 90th percentile had 2.62% (95% CI: 1.78%, 3.46%) and 0.95% (95% CI: 0.22%, 1.69%) increases in EDV for a duration of at least 2 days and 3 days respectively. The relative increase of EAD were 4.85% (95% CI: 1.42%, 8.39%) and 3.94% (95% CI: 0.88%, 7.10%). Varied effects of temperature and heat waves on emergency department visits and emergency ambulance dispatches were investigated. This wider view of the health effect of temperature indicated that interventions for both public health education and health services management should be considered in the study region.

High-Temperature Surface-Acoustic-Wave Transducer

NASA Technical Reports Server (NTRS)

Zhao, Xiaoliang; Tittmann, Bernhard R.

2010-01-01

Aircraft-engine rotating equipment usually operates at high temperature and stress. Non-invasive inspection of microcracks in those components poses a challenge for the non-destructive evaluation community. A low-profile ultrasonic guided wave sensor can detect cracks in situ. The key feature of the sensor is that it should withstand high temperatures and excite strong surface wave energy to inspect surface/subsurface cracks. As far as the innovators know at the time of this reporting, there is no existing sensor that is mounted to the rotor disks for crack inspection; the most often used technology includes fluorescent penetrant inspection or eddy-current probes for disassembled part inspection. An efficient, high-temperature, low-profile surface acoustic wave transducer design has been identified and tested for nondestructive evaluation of structures or materials. The development is a Sol-Gel bismuth titanate-based surface-acoustic-wave (SAW) sensor that can generate efficient surface acoustic waves for crack inspection. The produced sensor is very thin (submillimeter), and can generate surface waves up to 540 C. Finite element analysis of the SAW transducer design was performed to predict the sensor behavior, and experimental studies confirmed the results. One major uniqueness of the Sol-Gel bismuth titanate SAW sensor is that it is easy to implement to structures of various shapes. With a spray coating process, the sensor can be applied to surfaces of large curvatures. Second, the sensor is very thin (as a coating) and has very minimal effect on airflow or rotating equipment imbalance. Third, it can withstand temperatures up to 530 C, which is very useful for engine applications where high temperature is an issue.

Wave Rotor Research and Technology Development

NASA Technical Reports Server (NTRS)

Welch, Gerard E.

1998-01-01

Wave rotor technology offers the potential to increase the performance of gas turbine engines significantly, within the constraints imposed by current material temperature limits. The wave rotor research at the NASA Lewis Research Center is a three-element effort: 1) Development of design and analysis tools to accurately predict the performance of wave rotor components; 2) Experiments to characterize component performance; 3) System integration studies to evaluate the effect of wave rotor topping on the gas turbine engine system.

How Hot are Your Ions in TWAVE Ion Mobility Spectrometry?

PubMed Central

Merenbloom, Samuel I.; Flick, Tawnya G.; Williams, Evan R.

2012-01-01

Effective temperatures of ions during traveling wave ion mobility spectrometry (TWIMS) analysis were measured using singly protonated leucine enkephalin dimer as a chemical thermometer by monitoring dissociation of the dimer into monomer, as well as the subsequent dissociation of monomer into a-, b-, and y-ions, as a function of instrumental parameters. At fixed helium cell and TWIMS cell gas flow rates, the extent of dissociation does not vary significantly with either the wave velocity or wave height, except at low (<500 m/s) wave velocities that are not commonly used. Increasing the flow rate of nitrogen gas into the TWIMS cell and decreasing the flow rate of helium gas into the helium cell resulted in greater dissociation. However, the mobility distributions of the fragment ions formed by dissociation of the dimer upon injection into the TWIMS cell are nearly indistinguishable from those of fragment ions formed in the collision cell prior to TWIMS analysis for all TWIMS experiments. These results indicate that heating and dissociation occur when ions are injected into the TWIMS cell, and that the effective temperature subsequently decreases to a point at which no further dissociation is observed during the TWIMS analysis. An upper limit to the effective ion temperature of 449 K during TWIMS analysis is obtained at a helium flow rate of 180 mL/min, TWIMS flow rate of 80 mL/min and traveling wave height of 40 V, which is well below previously reported values. Effects of ion heating in TWIMS on gas-phase protein conformation are presented. PMID:22203576

In Situ Guided Wave Structural Health Monitoring System

NASA Technical Reports Server (NTRS)

Zhao, George; Tittmann, Bernhard R.

2011-01-01

Aircraft engine rotating equipment operates at high temperatures and stresses. Noninvasive inspection of microcracks in those components poses a challenge for nondestructive evaluation. A low-cost, low-profile, high-temperature ultrasonic guided wave sensor was developed that detects cracks in situ. The transducer design provides nondestructive evaluation of structures and materials. A key feature of the sensor is that it withstands high temperatures and excites strong surface wave energy to inspect surface and subsurface cracks. The sol-gel bismuth titanate-based surface acoustic wave (SAW) sensor can generate efficient SAWs for crack inspection. The sensor is very thin (submillimeter) and can generate surface waves up to 540 C. Finite element analysis of the SAW transducer design was performed to predict the sensor behavior, and experimental studies confirmed the results. The sensor can be implemented on structures of various shapes. With a spray-coating process, the sensor can be applied to the surface of large curvatures. It has minimal effect on airflow or rotating equipment imbalance, and provides good sensitivity.

Simultaneous measurement of temperature and emissivity of lunar regolith simulant using dual-channel millimeter-wave radiometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCloy, J. S.; Sundaram, S. K.; Matyas, J.

Millimeter wave (MMW) radiometry can be used for simultaneous measurement of emissivity and temperature of materials under extreme environments (high temperature, pressure, and corrosive environments). The state-of-the-art dual channel MMW passive radiometer with active interferometric capabilities at 137 GHz described here allows for radiometric measurements of sample temperature and emissivity up to at least 1600 °C with simultaneous measurement of sample surface dynamics. These capabilities have been used to demonstrate dynamic measurement of melting of powders of simulated lunar regolith and static measurement of emissivity of solid samples. The paper presents the theoretical background and basis for the dual-receiver system,more » describes the hardware in detail, and demonstrates the data analysis. Post-experiment analysis of emissivity versus temperature allows further extraction from the radiometric data of millimeter wave viewing beam coupling factors, which provide corroboratory evidence to the interferometric data of the process dynamics observed. Finally, these results show the promise of the MMW system for extracting quantitative and qualitative process parameters for industrial processes and access to real-time dynamics of materials behavior in extreme environments.« less

Whistler Waves With Electron Temperature Anisotropy And Non-Maxwellian Distribution Functions

NASA Astrophysics Data System (ADS)

Masood, W.

2017-12-01

Low frequency waves (˜ 100Hz), popularly known as Lion roars, are ubiquitously observed by satellites in terrestrial magnetosheath. By dint of both wave and electron data from the Cluster spacecraft and employing the linear kinetic theory for the electromagnetic waves, Masood et. al. (Ann. Geophysicae. 24, 1725-1735 (2006)) examined the conjecture made by Thorne and Tsurutani (Nature, 93, 384 (1981)) that whistler waves with electron temperature anisotropy are the progenitors of lion roars. It turned out that the study based upon the bi-Maxwellian distribution function did not come up with a satisfactory explanation of certain disagreements between theory and data. In this paper, we revisit the problem using the generalized (r, q) distribution to carry out the linear stability analysis. It is shown that good qualitative and quantitative agreements are found between theory and data using this distribution. Whistler waves with electron temperature anisotropy are also investigated with other non-Maxwellian distribution functions and general comparison is made in the end and differences in each case are highlighted. The possible applications in space plasmas are also pointed out.

The impact of gravity waves and cloud nucleation threshold on stratospheric water and tropical tropospheric cloud fraction

NASA Astrophysics Data System (ADS)

Schoeberl, Mark; Dessler, Andrew; Ye, Hao; Wang, Tao; Avery, Melody; Jensen, Eric

2016-08-01

Using the Modern Era Retrospective-Analysis for Research and Applications (MERRA) and MERRA-2 reanalysis winds, temperatures, and anvil cloud ice, we explore the impact of varying the cloud nucleation threshold relative humidity (RH) and high-frequency gravity waves on stratospheric water vapor (H2O) and upper tropical tropopause cloud fraction (TCF). Our model results are compared to 2008/2009 winter TCF derived from Cloud-Aerosol Lidar with Orthogonal Polarization and H2O observations from the Microwave Limb Sounder (MLS). The RH threshold affects both model H2O and TCF, while high-frequency gravity waves mostly impact TCF. Adjusting the nucleation RH and the amplitude of high-frequency gravity waves allows us to tune the model to observations. Reasonable observational agreement is obtained with a nucleation threshold between 130% and 150% RH consistent with airborne observations. For the MERRA reanalysis, we lower the tropopause temperature by 0.5 K roughly consistent with GPS radio occultation measurements and include ~0.1 K high-frequency gravity wave temperature oscillations in order to match TCF and H2O observations. For MERRA-2 we do not need to adjust the tropopause temperature nor add gravity waves, because there are sufficient high-frequency temperature oscillations already present in the MERRA-2 reanalysis to reproduce the observed TCF.

A mechanism to explain the variations of tropopause and tropopause inversion layer in the Arctic region during a sudden stratospheric warming in 2009

NASA Astrophysics Data System (ADS)

Wang, Rui; Tomikawa, Yoshihiro; Nakamura, Takuji; Huang, Kaiming; Zhang, Shaodong; Zhang, Yehui; Yang, Huigen; Hu, Hongqiao

2016-10-01

The mechanism to explain the variations of tropopause and tropopause inversion layer (TIL) in the Arctic region during a sudden stratospheric warming (SSW) in 2009 was studied with the Modern-Era Retrospective analysis for Research and Applications reanalysis data and GPS/Constellation Observing system for Meteorology, Ionosphere, and Climate (COSMIC) temperature data. During the prominent SSW in 2009, the cyclonic system changed to the anticyclonic system due to the planetary wave with wave number 2 (wave2). The GPS/COSMIC temperature data showed that during the SSW in 2009, the tropopause height in the Arctic decreased accompanied with the tropopause temperature increase and the TIL enhancement. The variations of the tropopause and TIL were larger in higher latitudes. A static stability analysis showed that the variations of the tropopause and TIL were associated with the variations of the residual circulation and the static stability due to the SSW. Larger static stability appeared in the upper stratosphere and moved downward to the narrow region just above the tropopause. The descent of strong downward flow was faster in higher latitudes. The static stability tendency analysis showed that the strong downward residual flow induced the static stability change in the stratosphere and around the tropopause. The strong downwelling in the stratosphere was mainly induced by wave2, which led to the tropopause height and temperature changes due to the adiabatic heating. Around the tropopause, a pair of downwelling above the tropopause and upwelling below the tropopause due to wave2 contributed to the enhancement of static stability in the TIL immediately after the SSW.

Evaluating Temperature Changes of Brain Tissue Due to Induced Heating of Cell Phone Waves.

PubMed

Forouharmajd, Farhad; Pourabdian, Siamak; Ebrahimi, Hossein

2018-01-01

Worries have recently been increased in the absorption of radiofrequency waves and their destructing effects on human health by increasing use of cell phones (mobile phones). This study performed to determine the thermal changes due to mobile phone radio frequency waves in gray and white brain tissue. This study is an empirical study, where the thermal changes of electromagnetic waves resulted from cell phones (900 MHZ, specific absorption rate for head 1.18 w/kg) on the 15 brain tissue of a cow were analyzed in a compartment with three different thickness of 2 mm, 12 mm, and 22 mm, for 15 min. The Lutron thermometer (model: MT-917) with 0.01°C precision was used for measuring the tissue temperature. For each thickness was measured three times. Data analysis is done by Lutron and MATLAB software packages. In confronting of the tissue with the cell phone, the temperature was increased by 0.53°C in the 2 mm thickness that is the gray matter of the brain, increased by 0.99°C in the 12 mm thickness, and also increased by 0.92°C in the 22 mm thickness. Brain temperature showed higher rates than the base temperature after 15 min of confrontation with cell phone waves in all the three thicknesses. Cell phone radiated radio frequency waves were effective on increasing brain tissue temperature, and this temperature increase has cumulative effect on the tissue, being higher, for some time after the confrontation than the time with no confrontation.

Evaluating Temperature Changes of Brain Tissue Due to Induced Heating of Cell Phone Waves

PubMed Central

Forouharmajd, Farhad; Pourabdian, Siamak; Ebrahimi, Hossein

2018-01-01

Background: Worries have recently been increased in the absorption of radiofrequency waves and their destructing effects on human health by increasing use of cell phones (mobile phones). This study performed to determine the thermal changes due to mobile phone radio frequency waves in gray and white brain tissue. Methods: This study is an empirical study, where the thermal changes of electromagnetic waves resulted from cell phones (900 MHZ, specific absorption rate for head 1.18 w/kg) on the 15 brain tissue of a cow were analyzed in a compartment with three different thickness of 2 mm, 12 mm, and 22 mm, for 15 min. The Lutron thermometer (model: MT-917) with 0.01°C precision was used for measuring the tissue temperature. For each thickness was measured three times. Data analysis is done by Lutron and MATLAB software packages. Results: In confronting of the tissue with the cell phone, the temperature was increased by 0.53°C in the 2 mm thickness that is the gray matter of the brain, increased by 0.99°C in the 12 mm thickness, and also increased by 0.92°C in the 22 mm thickness. Brain temperature showed higher rates than the base temperature after 15 min of confrontation with cell phone waves in all the three thicknesses. Conclusions: Cell phone radiated radio frequency waves were effective on increasing brain tissue temperature, and this temperature increase has cumulative effect on the tissue, being higher, for some time after the confrontation than the time with no confrontation. PMID:29861880

Do gravity waves significantly impact PSC occurrence in the Antarctic?

NASA Astrophysics Data System (ADS)

McDonald, A. J.; George, S. E.; Woollands, R. M.

2009-02-01

This study uses a combination of POAM III aerosol extinction measurements and CHAMP GPS/RO temperature measurements to examine the role of atmospheric gravity waves in Polar Stratospheric Cloud (PSC) formation in the Antarctic. POAM III aerosol extinction observations are used to identify Type I Polar Stratospheric Clouds using an unsupervised clustering algorithm. The seasonal and spatial distribution of PSCs observed by POAM III is examined to determine whether there is a bias towards regions of high wave activity early in the Antarctic winter which may enhance PSC formation. Examination of the probability of temperatures below the Type Ia formation temperature threshold based on UKMO analyses displays a good correspondence to the PSC occurrence derived from POAM III extinction data in general. However, in June the POAM III observations of PSC are more abundant than expected from temperature thresholds. In addition the PSC occurrence based on temperature thresholds in September and October is often significantly higher than the PSC occurrence observed by POAM III, this observation probably being due to dehydration and denitrification. Use of high resolution temperatures from CHAMP GPS/RO observations provide a slightly improved relationship to the POAM III derived values. Analysis of the CHAMP temperature observations indicates that temperature perturbations associated with gravity waves may explain the enhanced PSC incidence observed in June compared to the UKMO analyses. Comparison of the UKMO analyses temperatures relative to corresponding CHAMP observations also suggests a small warm bias in the UKMO analyses during June. Examination of the longitudinal structure PSC occurrence in June 2005 also shows that regions of enhancement are associated with data near the Antarctic peninsula a known Mountain wave "hotspot". The impact of temperature perturbations causing enhanced temperature threshold crossings is shown to be particularly important early in the Antarctic winter while later in the season temperature perturbations associated with gravity waves could contribute to about 15% of the PSC observed, a value which corresponds well to several previous studies.

Influence of temperature on linear stability in buoyancy-driven fingering of reaction-diffusion fronts.

PubMed

Levitán, D; D'Onofrio, A

2012-09-01

A vertical Hele-Shaw cell was used to study the influence of temperature on Rayleigh-Taylor instabilities on reaction-diffusion fronts. The propagation of the chemical front can thus be observed, and experimental results can be obtained via image treatment. A chemical front produced by the coupling between molecular diffusion and the auto-catalysis of the chlorite-tetrathionate reaction, descends through the cell, consuming the reactants below while the product is formed above. Buoyancy-driven instabilities are formed due to the density difference between reactants and products, and the front takes a fingering pattern, whose growth rate has temperature dependence. In this study, the effect of temperature on the linear regime of the instability (that is, when the effects of such instability start to appear) was analyzed. To measure the instability, Fourier transform analysis is performed, in order to obtain the different wave numbers and their power as a function of time. Thus, the growth rate for each wave number and the most unstable wave number is obtained for each of the temperatures under study. Based on repeated experiments, a decrease in the growth rate for the most unstable wave number can be observed with the increase of temperature.

Ultrasound Analysis of Slurries

DOEpatents

Soong, Yee and Blackwell, Arthur G.

2005-11-01

An autoclave reactor allows for the ultrasonic analysis of slurry concentration and particle size distribution at elevated temperatures and pressures while maintaining the temperature- and pressure-sensitive ultrasonic transducers under ambient conditions. The reactor vessel is a hollow stainless steel cylinder containing the slurry which includes a stirrer and a N, gas source for directing gas bubbles through the slurry. Input and output transducers are connected to opposed lateral portions of the hollow cylinder for respectively directing sound waves through the slurry and receiving these sound waves after transmission through the slurry, where changes in sound wave velocity and amplitude can be used to measure slurry parameters. Ultrasonic adapters connect the transducers to the reactor vessel in a sealed manner and isolate the transducers from the hostile conditions within the vessel without ultrasonic signal distortion or losses.

Ultrasound Analysis Of Slurries

DOEpatents

Soong, Yee; Blackwell, Arthur G.

2005-11-01

An autoclave reactor allows for the ultrasonic analysis of slurry concentration and particle size distribution at elevated temperatures and pressures while maintaining the temperature- and pressure-sensitive ultrasonic transducers under ambient conditions. The reactor vessel is a hollow stainless steel cylinder containing the slurry which includes a stirrer and a N.sub.2 gas source for directing gas bubbles through the slurry. Input and output transducers are connected to opposed lateral portions of the hollow cylinder for respectively directing sound waves through the slurry and receiving these sound waves after transmission through the slurry, where changes in sound wave velocity and amplitude can be used to measure slurry parameters. Ultrasonic adapters connect the transducers to the reactor vessel in a sealed manner and isolate the transducers from the hostile conditions within the vessel without ultrasonic signal distortion or losses.

Underwater optical communication performance for laser beam propagation through weak oceanic turbulence.

PubMed

Yi, Xiang; Li, Zan; Liu, Zengji

2015-02-20

In clean ocean water, the performance of a underwater optical communication system is limited mainly by oceanic turbulence, which is defined as the fluctuations in the index of refraction resulting from temperature and salinity fluctuations. In this paper, using the refractive index spectrum of oceanic turbulence under weak turbulence conditions, we carry out, for a horizontally propagating plane wave and spherical wave, analysis of the aperture-averaged scintillation index, the associated probability of fade, mean signal-to-noise ratio, and mean bit error rate. Our theoretical results show that for various values of the rate of dissipation of mean squared temperature and the temperature-salinity balance parameter, the large-aperture receiver leads to a remarkable decrease of scintillation and consequently a significant improvement on the system performance. Such an effect is more noticeable in the plane wave case than in the spherical wave case.

Temperature increases on the external root surface during endodontic treatment using single file systems.

PubMed

Özkocak, I; Taşkan, M M; Gökt Rk, H; Aytac, F; Karaarslan, E Şirin

2015-01-01

The aim of this study is to evaluate increases in temperature on the external root surface during endodontic treatment with different rotary systems. Fifty human mandibular incisors with a single root canal were selected. All root canals were instrumented using a size 20 Hedstrom file, and the canals were irrigated with 5% sodium hypochlorite solution. The samples were randomly divided into the following three groups of 15 teeth: Group 1: The OneShape Endodontic File no.: 25; Group 2: The Reciproc Endodontic File no.: 25; Group 3: The WaveOne Endodontic File no.: 25. During the preparation, the temperature changes were measured in the middle third of the roots using a noncontact infrared thermometer. The temperature data were transferred from the thermometer to the computer and were observed graphically. Statistical analysis was performed using the Kruskal-Wallis analysis of variance at a significance level of 0.05. The increases in temperature caused by the OneShape file system were lower than those of the other files (P < 0.05). The WaveOne file showed the highest temperature increases. However, there were no significant differences between the Reciproc and WaveOne files. The single file rotary systems used in this study may be recommended for clinical use.

The 2011 heat wave in Greater Houston: Effects of land use on temperature.

PubMed

Zhou, Weihe; Ji, Shuang; Chen, Tsun-Hsuan; Hou, Yi; Zhang, Kai

2014-11-01

Effects of land use on temperatures during severe heat waves have been rarely studied. This paper examines land use-temperature associations during the 2011 heat wave in Greater Houston. We obtained high resolution of satellite-derived land use data from the US National Land Cover Database, and temperature observations at 138 weather stations from Weather Underground, Inc (WU) during the August of 2011, which was the hottest month in Houston since 1889. Land use regression and quantile regression methods were applied to the monthly averages of daily maximum/mean/minimum temperatures and 114 land use-related predictors. Although selected variables vary with temperature metric, distance to the coastline consistently appears among all models. Other variables are generally related to high developed intensity, open water or wetlands. In addition, our quantile regression analysis shows that distance to the coastline and high developed intensity areas have larger impacts on daily average temperatures at higher quantiles, and open water area has greater impacts on daily minimum temperatures at lower quantiles. By utilizing both land use regression and quantile regression on a recent heat wave in one of the largest US metropolitan areas, this paper provides a new perspective on the impacts of land use on temperatures. Our models can provide estimates of heat exposures for epidemiological studies, and our findings can be combined with demographic variables, air conditioning and relevant diseases information to identify 'hot spots' of population vulnerability for public health interventions to reduce heat-related health effects during heat waves. Copyright © 2014 Elsevier Inc. All rights reserved.

Relationship between the upper mantle high velocity seismic lid and the continental lithosphere

NASA Astrophysics Data System (ADS)

Priestley, Keith; Tilmann, Frederik

2009-04-01

The lithosphere-asthenosphere boundary corresponds to the base of the "rigid" plates - the depth at which heat transport changes from advection in the convecting deeper upper mantle to conduction in the shallow upper mantle. Although this boundary is a fundamental feature of the Earth, mapping it has been difficult because it does not correspond to a sharp change in temperature or composition. Various definitions of the lithosphere and asthenosphere are based on the analysis of different types of geophysical and geological observations. The depth to the lithosphere-asthenosphere boundary determined from these different observations often shows little agreement when they are applied to the same region because the geophysical and geological observations (i.e., seismic velocity, strain rate, electrical resistivity, chemical depletion, etc.) are proxies for the change in rheological properties rather than a direct measure of the rheological properties. In this paper, we focus on the seismic mapping of the upper mantle high velocity lid and low velocity zone and its relationship to the lithosphere and asthenosphere. We have two goals: (a) to examine the differences in how teleseismic body-wave travel-time tomography and surface-wave tomography image upper mantle seismic structure; and (b) to summarise how upper mantle seismic velocity structure can be related to the structure of the lithosphere and asthenosphere. Surface-wave tomography provides reasonably good depth resolution, especially when higher modes are included in the analysis, but lateral resolution is limited by the horizontal wavelength of the long-period surface waves used to constrain upper mantle velocity structure. Teleseismic body-wave tomography has poor depth resolution in the upper mantle, particularly when no strong lateral contrasts are present. If station terms are used, features with large lateral extent and gradual boundaries are attenuated in the tomographic image. Body-wave models are not useful in mapping the thickness of the high velocity upper mantle lid because this type of analysis often determines wave speed perturbations from an unknown horizontal average and not absolute velocities. Thus, any feature which extends laterally across the whole region beneath a seismic network becomes invisible in the teleseismic body-wave tomographic image. We compare surface-wave and body-wave tomographic results using southern Africa as an example. Surface-wave tomographic images for southern Africa show a strong, high velocity upper mantle lid confined to depths shallower than ~ 200 km, whereas body-wave tomographic images show weak high velocity in the upper mantle extending to depths of ~ 300 km or more. However, synthetic tests show that these results are not contradictory. The absolute seismic velocity structure of the upper mantle provided by surface wave analysis can be used to map the thermal lithosphere. Priestley and McKenzie (Priestley, K., McKenzie, D., 2006. The thermal structure of the lithosphere from shear wave velocities. Earth and Planetary Science Letters 244, 285-301.) derive an empirical relationship between shear wave velocity and temperature. This relationship is used to obtain temperature profiles from the surface-wave tomographic models of the continental mantle. The base of the lithosphere is shown by a change in the gradient of the temperature profiles indicative of the depth where the mode of heat transport changes from conduction to advection. Comparisons of the geotherms determined from the conversion of surface-wave wave speeds to temperatures with upper mantle nodule-derived geotherms demonstrate that estimates of lithospheric thickness from Vs and from the nodule mineralogy agree to within about 25 km. The lithospheric thickness map for Africa derived from the surface-wave tomographic results shows that thick lithosphere underlies most of the Archean crust in Africa. The distribution of diamondiferous kimberlites provides an independent estimate of where thick lithosphere exists. Diamondiferous kimberlites generally occur where the lower part of the thermal lithosphere as indicated by seismology is in the diamond stability field.

Long-term Global Morphology of Gravity Wave Activity Using UARS Data

NASA Technical Reports Server (NTRS)

Eckermann, Stephen D.; Jackman, C. (Technical Monitor)

2000-01-01

This quarter was largely devoted to a detailed study of temperature data acquired by the Cryogenic Limb Array Etalon Spectrometer (CLAES) on UARS. Our analysis used the same sequence of methods that have been developed, tested and refined on a more limited subset of temperature data acquired by the CRISTA instrument. We focused on a limited subset of our reasoning that geographical and vertical trends in the small-scale temperature variability could be compared with similar trends observed in November 1994 by the CRISTA-SPAS satellite. Results, backed up with hindcasts from the Mountain Wave Forecast Model (MWFM), reveal strong evidence of mountain waves, most persuasively in the Himalayas on 16-17 November, 1992. These CLAES results are coherent over the 30-50 km range and compare well with MWFM hindcasts for the same period. This constitutes, we believe, the first clear evidence that CLAES explicitly resolved long wavelength gravity waves in its CO2 temperature channel. A series of other tasks, related to mesoscale modeling of mountain waves in CRISTA data and fitting of ground-based and HRDI data on global scales, were seen through to publication stage in peer-reviewed journals.

Was there a basis for anticipating the 2010 Russian heat wave?

NASA Astrophysics Data System (ADS)

Dole, Randall; Hoerling, Martin; Perlwitz, Judith; Eischeid, Jon; Pegion, Philip; Zhang, Tao; Quan, Xiao-Wei; Xu, Taiyi; Murray, Donald

2011-03-01

The 2010 summer heat wave in western Russia was extraordinary, with the region experiencing the warmest July since at least 1880 and numerous locations setting all-time maximum temperature records. This study explores whether early warning could have been provided through knowledge of natural and human-caused climate forcings. Model simulations and observational data are used to determine the impact of observed sea surface temperatures (SSTs), sea ice conditions and greenhouse gas concentrations. Analysis of forced model simulations indicates that neither human influences nor other slowly evolving ocean boundary conditions contributed substantially to the magnitude of this heat wave. They also provide evidence that such an intense event could be produced through natural variability alone. Analysis of observations indicate that this heat wave was mainly due to internal atmospheric dynamical processes that produced and maintained a strong and long-lived blocking event, and that similar atmospheric patterns have occurred with prior heat waves in this region. We conclude that the intense 2010 Russian heat wave was mainly due to natural internal atmospheric variability. Slowly varying boundary conditions that could have provided predictability and the potential for early warning did not appear to play an appreciable role in this event.

Definition of temperature thresholds: the example of the French heat wave warning system.

PubMed

Pascal, Mathilde; Wagner, Vérène; Le Tertre, Alain; Laaidi, Karine; Honoré, Cyrille; Bénichou, Françoise; Beaudeau, Pascal

2013-01-01

Heat-related deaths should be somewhat preventable. In France, some prevention measures are activated when minimum and maximum temperatures averaged over three days reach city-specific thresholds. The current thresholds were computed based on a descriptive analysis of past heat waves and on local expert judgement. We tested whether a different method would confirm these thresholds. The study was set in the six cities of Paris, Lyon, Marseille, Nantes, Strasbourg and Limoges between 1973 and 2003. For each city, we estimated the excess in mortality associated with different temperature thresholds, using a generalised additive model, controlling for long-time trends, seasons and days of the week. These models were used to compute the mortality predicted by different percentiles of temperatures. The thresholds were chosen as the percentiles associated with a significant excess mortality. In all cities, there was a good correlation between current thresholds and the thresholds derived from the models, with 0°C to 3°C differences for averaged maximum temperatures. Both set of thresholds were able to anticipate the main periods of excess mortality during the summers of 1973 to 2003. A simple method relying on descriptive analysis and expert judgement is sufficient to define protective temperature thresholds and to prevent heat wave mortality. As temperatures are increasing along with the climate change and adaptation is ongoing, more research is required to understand if and when thresholds should be modified.

Electrically-Active Convection and Tropical Cyclogenesis in the Atlantic and East Pacific

NASA Technical Reports Server (NTRS)

Leppert, Kenneth D., II; Petersen, Walter A.

2011-01-01

It has been hypothesized that deep, intense convective-scale hot towers may aid the process of tropical cyclogenesis and intensification through dynamic and thermodynamic feedbacks on the larger meso-to-synoptic scale circulation. In this study, we make use of NCEP Reanalysis data and Tropical Rainfall Measurement Mission (TRMM) lightning imaging sensor (LIS), precipitation radar (PR), and microwave imager (TMI) data to investigate the role that widespread and/or intense lightning-producing convection (i.e., electrically-hot towers) present in African easterly waves (AEWs) may play in tropical cyclogenesis over the Atlantic, Caribbean, and East Pacific regions. NCEP Reanalysis 700 hPa meridional winds for the months of June to November for the years 2001-2009 were analyzed for the domain of 5 deg. N-20 deg. N and 130 deg. W-20 deg. E in order to partition individual AEWs into northerly, southerly, trough, and ridge phases. Subsequently, information from National Hurricane Center (NHC) storm reports was used to divide the waves into developing and non-developing waves. In addition, information from the NHC reports was used to further divide the developing waves into those waves that spawned storms that only developed to tropical storm strength and those that spawned storms that reached hurricane strength. The developing waves were also divided by the region in which they developed. To assess the evolution of convection associated with the AEWs as they propagated across our analysis domain, the full 130 deg. W-20 deg. E domain was divided into five longitude bands, and waves were analyzed for each band. To help determine the gross nature of the smaller convective scale, composites were created of all developing and non-developing waves as a function of AEW wave phase over the full analysis domain and each longitude band by compositing TRMM PR, TMI, LIS, and IR brightness temperature data extracted from the NASA global-merged infrared brightness temperature dataset. Finally, similar composites were created using various NCEP variables to assess the nature of the larger scale environment and circulation. Results suggest a clear distinction between developing and non-developing waves as developing waves near their region of development in terms of the intensity of convection (indicated by lightning flash rate), coverage of cold cloudiness (indicated by the percentage of a 2.5 deg. by 2.5 deg. box covered by IR brightness temperatures less than 240 deg. K and 210 deg. K), and large-scale variables, such as midlevel moisture and upper-level upward motion. For example, waves that developed in the East Pacific longitude band (i.e., 130 deg. W 95 deg. W) were observed in that band to have a flash rate of 56.4 flashes per day, a coverage by brightness temperatures less than 240 deg. K equal to 15.9%, a coverage by brightness temperatures less than 210 deg. K equal to 2.2%, a 700-hPa specific humidity anomaly of 0.4 g per kilogram, and a 300-hPa omega value of -0.04 Pascals per second in the trough phase compared to the non-developing wave trough values of 22.1 flashes per day, a coverage by brightness temperatures less than 240 deg. K equal to 8.1%, a coverage by brightness temperatures less than 210 deg. K equal to 0.9%, a 700-hPa specific humidity anomaly of -0.3 g per kilogram, and a 300-hPa omega value of -0.01 Pascals per second. Further analysis is being conducted to determine if the aforementioned behavior is observed for developing waves farther from their region of development and to determine any significant differences between waves that spawned storms that reached tropical storm strength and those that spawned storms that reached hurricane strength.

An ignition-temperature model with two free interfaces in premixed flames

NASA Astrophysics Data System (ADS)

Brauner, Claude-Michel; Gordon, Peter V.; Zhang, Wen

2016-11-01

In this paper we consider an ignition-temperature zero-order reaction model of thermo-diffusive combustion. This model describes the dynamics of thick flames, which have recently received considerable attention in the physical and engineering literature. The model admits a unique (up to translations) planar travelling wave solution. This travelling wave solution is quite different from those usually studied in combustion theory. The main qualitative feature of this travelling wave is that it has two interfaces: the ignition interface where the ignition temperature is attained and the trailing interface where the concentration of deficient reactants reaches zero. We give a new mathematical framework for studying the cellular instability of such travelling front solutions. Our approach allows the analysis of a free boundary problem to be converted into the analysis of a boundary value problem having a fully nonlinear system of parabolic equations. The latter is very suitable for both mathematical and numerical analysis. We prove the existence of a critical Lewis number such that the travelling wave solution is stable for values of Lewis number below the critical one and is unstable for Lewis numbers that exceed this critical value. Finally, we discuss the results of numerical simulations of a fully nonlinear system that describes the perturbation dynamics of planar fronts. These simulations reveal, in particular, some very interesting 'two-cell' steady patterns of curved combustion fronts.

Suppressive Shields Structural Design and Analysis Handbook

DTIC Science & Technology

1977-11-18

of this disturbance to steepen as it passes through the air until it exhibits nearly discontinuous increases in pressure, density, and temperature ...sure. density, and temperature of the reflected wave are all in- creased above the values in the incident wave. The ove-nressure at the wall surface...limiting thickness of concrete at which per- foration will occur can be obtained from Fig. 3-18 and is a function of the coefficient C1, the fragment weight

Standing Waves in an Elastic Spring: A Systematic Study by Video Analysis

NASA Astrophysics Data System (ADS)

Ventura, Daniel Rodrigues; de Carvalho, Paulo Simeão; Dias, Marco Adriano

2017-04-01

The word "wave" is part of the daily language of every student. However, the physical understanding of the concept demands a high level of abstract thought. In physics, waves are oscillating variations of a physical quantity that involve the transfer of energy from one point to another, without displacement of matter. A wave can be formed by an elastic deformation, a variation of pressure, changes in the intensity of electric or magnetic fields, a propagation of a temperature variation, or other disturbances. Moreover, a wave can be categorized as pulsed or periodic. Most importantly, conditions can be set such that waves interfere with one another, resulting in standing waves. These have many applications in technology, although they are not always readily identified and/or understood by all students. In this work, we use a simple setup including a low-cost constant spring, such as a Slinky, and the free software Tracker for video analysis. We show they can be very useful for the teaching of mechanical wave propagation and the analysis of harmonics in standing waves.

A comparison of thermocouple and infrared thermographic analysis of temperature rise on the root surface during the continuous wave of condensation technique.

PubMed

Mc Cullagh, J J; Setchell, D J; Gulabivala, K; Hussey, D L; Biagioni, P; Lamey, P J; Bailey, G

2000-07-01

This study was designed to use two methods of temperature measurement to analyse and quantify the in vitro root surface temperature changes during the initial stage of the continuous wave technique of obturation of 17 single-rooted premolar teeth with standard canal preparations. A model was designed to allow simultaneous temperature measurement with both thermocouples and an infrared thermal imaging system. Two thermocouples were placed on the root surface, one coronally and the other near the root apex. A series of thermal images were recorded by an infrared thermal imaging camera during the downpack procedure. The mean temperature rises on the root surface, as measured by the two thermocouples, averaged 13.9 degrees C over the period of study, whilst the infrared thermal imaging system measured an average rise of 28.4 degrees C at the same sites. Temperatures at the more apical point were higher than those measured coronally. After the first wave of condensation, the second activation of the plugger in the canal prior to its removal always resulted in a secondary rise in temperature. The thermal imaging system detected areas of greater temperature change distant from the two selected thermocouple sites. The continuous wave technique of obturation may result in high temperatures on the external root surface. Infrared thermography is a useful device for mapping patterns of temperature change over a large area.

Gyrokinetic-water-bag modeling of low-frequency instabilities in a laboratory magnetized plasma column

NASA Astrophysics Data System (ADS)

Gravier, E.; Klein, R.; Morel, P.; Besse, N.; Bertrand, P.

2008-12-01

A new model is presented, named collisional-gyro-water-bag (CGWB), which describes the collisional drift waves and ion-temperature-gradient (ITG) instabilities in a plasma column. This model is based on the kinetic gyro-water-bag approach recently developed [P. Morel et al., Phys. Plasmas 14, 112109 (2007)] to investigate ion-temperature-gradient modes. In CGWB electron-neutral collisions have been introduced and are now taken into account. The model has been validated by comparing CGWB linear analysis with other models previously proposed and experimental results as well. Kinetic effects on collisional drift waves are investigated, resulting in a less effective growth rate, and the transition from collisional drift waves to ITG instability depending on the ion temperature gradient is studied.

The resistance to deformation and facture of magnesium ma2-1 under shock-wave loading at 293 k and 823 k of the temperature

NASA Astrophysics Data System (ADS)

Garkushin, Gennady; Kanel, Gennady I.; Razorenov, Sergey V.

2012-03-01

The Hugoniot elastic limit and spall strength of Ma2-1 magnesium deformable alloy were measured at the sample thickness varied from 0.25 mm to 10 mm at room and elevated temperatures. By means of analysis of decay of an elastic precursor wave it is found that initial plastic strain rate decreases from 2×105 s-1 at distance of 0.25 mm to 103 s-1 at distance of 10 mm. The strain rate in plastic shock wave is by order of magnitude higher at the same value of the shear stress. The spall strength of the alloy grows with increasing the strain rate and decreases with approach to the solidus temperature.

Mid-Latitude Temperatures at 87 km: Results From Multi-Instrument Fourier Analysis

NASA Technical Reports Server (NTRS)

Drob, Douglas P.; Picone, J. M.; Eckermann, Stephen D.; She, C . Y.; Kafkalidis, J. F.; Ortland, D. A.; Niciejewski, R. J.; Killeen, T. L.

2000-01-01

Using a novel Fourier fitting method we combine two years of mid-latitude temperature measurements at 87 km from the High Resolution Doppler Imager, the Colorado State University lidar, and the Peach Mountain Interferometer. After accounting for calibration bias, significant local-time variations on the order of 10 K were observed. Stationary planetary waves with amplitudes up to 10 K were observed during winter, with weaker wave amplitudes occurring during other seasons. Because of calibration biases among these instruments, we could estimate the annual mean temperature to no better than 193.5 plus or minus 8.5 K.

Nonlinear Korteweg-de Vries-Burger equation for ion acoustic shock waves in a weakly relativistic electron-positron-ion plasma with thermal ions

NASA Astrophysics Data System (ADS)

Saeed, R.; Shah, Asif

2010-03-01

The nonlinear propagation of ion acoustic waves in electron-positron-ion plasma comprising of Boltzmannian electrons, positrons, and relativistic thermal ions has been examined. The Korteweg-de Vries-Burger equation has been derived by reductive perturbation technique, and its shock like solution is determined analytically through tangent hyperbolic method. The effect of various plasma parameters on strength and structure of shock wave is investigated. The pert graphical view of the results has been presented for illustration. It is observed that strength and steepness of the shock wave enervate with an increase in the ion temperature, relativistic streaming factor, positron concentrations, electron temperature and they accrue with an increase in coefficient of kinematic viscosity. The convective, dispersive, and dissipative properties of the plasma are also discussed. It is determined that the electron temperature has remarkable influence on the propagation and structure of nonlinear wave in such relativistic plasmas. The numerical analysis has been done based on the typical numerical data from a pulsar magnetosphere.

Ultrasonic Method for Measuring Internal Temperature Profile in Heated Materials

NASA Astrophysics Data System (ADS)

Ihara, I.; Takahashi, M.

2008-02-01

A new ultrasonic method for internal temperature measurement is presented. The principle of the method is based on temperature dependence of the velocity of the ultrasonic wave propagating through the material. An inverse analysis to determine the temperature profile in a heated material is developed and an experiment is carried out to verify the validity of the developed method. A single side of a silicone rubber plate of 30 mm thickness is heated and ultrasonic pulse-echo measurements are then performed during heating. A change in transit time of ultrasonic wave in the heated rubber plate is monitored and used to determine the transient variation in internal temperature distribution of the rubber. The internal temperature distribution determined ultrasonically agrees well with both obtained using commercial thermocouples installed in the rubber and estimated theoretically.

Projection of heat waves over China for eight different global warming targets using 12 CMIP5 models

NASA Astrophysics Data System (ADS)

Guo, Xiaojun; Huang, Jianbin; Luo, Yong; Zhao, Zongci; Xu, Ying

2017-05-01

Simulation and projection of the characteristics of heat waves over China were investigated using 12 CMIP5 global climate models and the CN05.1 observational gridded dataset. Four heat wave indices (heat wave frequency, longest heat wave duration, heat wave days, and high temperature days) were adopted in the analysis. Evaluations of the 12 CMIP5 models and their ensemble indicated that the multi-model ensemble could capture the spatiotemporal characteristics of heat wave variation over China. The inter-decadal variations of heat waves during 1961-2005 can be well simulated by multi-model ensemble. Based on model projections, the features of heat waves over China for eight different global warming targets (1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, and 5.0 °C) were explored. The results showed that the frequency and intensity of heat waves would increase more dramatically as the global mean temperature rise attained higher warming targets. Under the RCP8.5 scenario, the four China-averaged heat wave indices would increase from about 1.0 times/year, 2.5, 5.4, and 13.8 days/year to about 3.2 times/year, 14.0, 32.0, and 31.9 days/year for 1.5 and 5.0 °C warming targets, respectively. Those regions that suffer severe heat waves in the base climate would experience the heat waves with greater frequency and severity following global temperature rise. It is also noteworthy that the areas in which a greater number of severe heat waves occur displayed considerable expansion. Moreover, the model uncertainties exhibit a gradual enhancement with projected time extending from 2006 to 2099.

Ab initio computation of the transition temperature of the charge density wave transition in TiS e2

NASA Astrophysics Data System (ADS)

Duong, Dinh Loc; Burghard, Marko; Schön, J. Christian

2015-12-01

We present a density functional perturbation theory approach to estimate the transition temperature of the charge density wave transition of TiS e2 . The softening of the phonon mode at the L point where in TiS e2 a giant Kohn anomaly occurs, and the energy difference between the normal and distorted phase are analyzed. Both features are studied as functions of the electronic temperature, which corresponds to the Fermi-Dirac distribution smearing value in the calculation. The transition temperature is found to be 500 and 600 K by phonon and energy analysis, respectively, in reasonable agreement with the experimental value of 200 K.

THE CHROMOSPHERIC SOLAR MILLIMETER-WAVE CAVITY ORIGINATES IN THE TEMPERATURE MINIMUM REGION

DOE Office of Scientific and Technical Information (OSTI.GOV)

De la Luz, Victor; Raulin, Jean-Pierre; Lara, Alejandro

2013-01-10

We present a detailed theoretical analysis of the local radio emission at the lower part of the solar atmosphere. To accomplish this, we have used a numerical code to simulate the emission and transport of high-frequency electromagnetic waves from 2 GHz up to 10 THz. As initial conditions, we used VALC, SEL05, and C7 solar chromospheric models. In this way, the generated synthetic spectra allow us to study the local emission and absorption processes with high resolution in both altitude and frequency. Associated with the temperature minimum predicted by these models, we found that the local optical depth at millimetermore » wavelengths remains constant, producing an optically thin layer that is surrounded by two layers of high local emission. We call this structure the Chromospheric Solar Millimeter-wave Cavity (CSMC). The temperature profile, which features temperature minimum layers and a subsequent temperature rise, produces the CSMC phenomenon. The CSMC shows the complexity of the relation between the theoretical temperature profile and the observed brightness temperature and may help us to understand the dispersion of the observed brightness temperature in the millimeter wavelength range.« less

Equatorial Kelvin waves: A UARS MLS view

NASA Technical Reports Server (NTRS)

Canziani, Pablo O.; Holton, James R.; Fishbein, Evan; Froidevaux, Lucien; Waters, Joe W.

1994-01-01

Data from the Microwave Limb Sounder (MLS) instrument on the Upper Atmosphere Research Satellite (UARS) are used to compare two periods of Kelvin wave activity during different stages of the equatorial quasi-biennial oscillation. The analysis is carried out using an asynoptic mapping technique. A wide bandpass filter is used to isolate the frequency bands where Kelvin waves have been identified in previous studies. Time-height and time-latitude plots of the bandpassed data are used to identify Kelvin wave activity in the temperature and ozone fields. Frequency spectra of temperature and ozone amplitudes are constructed to further analyze the latitudinal and meridional distribution of Kelvin wave activity in zonal wavenumbers 1 and 2. The characteristics identified in these plots agree well with theoretical predictions and previous observations of middle atmosphere Kelvin waves. The time-height and time-latitude plots support the existence of Kelvin waves in discrete frequency bands; the slow, fast, and ultrafast Kelvin modes are all identified in the data. The characteristics of these modes do not vary much despite different mean flow conditions in the two periods examined. For the Kelvin wave-induced perturbations in ozone, the change from a transport-dominated regime below 10 hPa to a photochemically controlled regime above 10 hPa is clearly apparent in the height dependence of the phase difference between temperature and ozone. The ratios of the ozone perturbation amplitude to the temperature perturbation amplitude for the various observed Kelvin wave modes are in agreement with model estimates and LIMS (Limb Infrared Monitor of the Stratosphere) observations in the lower half of the region sampled but appear to be too large in the upper stratosphere and lower mesosphere.

Study of gravity waves propagation in the thermosphere of Mars based on MAVEN/NGIMS density measurements

NASA Astrophysics Data System (ADS)

Vals, M.

2017-09-01

We use MAVEN/NGIMS CO2 density measurements to analyse gravity waves in the thermosphere of Mars. In particular the seasonal/latitudinal variability of their amplitude is studied and interpreted. Key background parameters controlling the activity of gravity waves are analysed with the help of the Mars Climate Database (MCD). Gravity waves activity presents a good anti-correlation to the temperature variability retrieved from the MCD. An analysis at pressure levels is ongoing.

On the sensitivities of idealized moist baroclinic waves to environmental temperature and moist convection

NASA Astrophysics Data System (ADS)

Kirshbaum, Daniel; Merlis, Timothy; Gyakum, John; McTaggart-Cowan, Ron

2017-04-01

The impact of cloud diabatic heating on baroclinic life cycles has been studied for decades, with the nearly universal finding that this heating enhances the system growth rate. However, few if any studies have systematically addressed the sensitivity of baroclinic waves to environmental temperature. For a given relative humidity, warmer atmospheres contain more moisture than colder atmospheres. They also are more prone to the development of deep moist convection, which is itself a major source of diabatic heating. Thus, it is reasonable to expect faster baroclinic wave growth in warmer systems. To address this question, this study performs idealized simulations of moist baroclinic waves in a periodic channel, using initial environments with identical relative humidities, dry stabilities, and dry available potential energies but varying environmental temperatures and moist instabilities. While the dry versions of these simulations exhibit virtually identical wave growth, the moist versions exhibit major differences in life cycle. Counter-intuitively, despite slightly faster initial wave growth, the warmer and moister waves ultimately develop into weaker baroclinic systems with an earlier onset of the decay phase. An energetics analysis reveals that the reduced wave amplitude in the warmer cases stems from a reduced transfer of available potential energy into eddy potential energy. This reduced energy transfer is associated with an unfavorable phasing of mid-to-upper-level thermal and vorticity anomalies, which limits the meridional heat flux.

Short and long periodic atmospheric variations between 25 and 200 km

NASA Technical Reports Server (NTRS)

Justus, C. G.; Woodrum, A.

1973-01-01

Previously collected data on atmospheric pressure, density, temperature and winds between 25 and 200 km from sources including Meteorological Rocket Network data, ROBIN falling sphere data, grenade release and pitot tube data, meteor winds, chemical release winds, satellite data, and others were analyzed by a daily difference method and results on the distribution statistics, magnitude, and spatial structure of gravity wave and planetary wave atmospheric variations are presented. Time structure of the gravity wave variations were determined by the analysis of residuals from harmonic analysis of time series data. Planetary wave contributions in the 25-85 km range were discovered and found to have significant height and latitudinal variation. Long period planetary waves, and seasonal variations were also computed by harmonic analysis. Revised height variations of the gravity wave contributions in the 25 to 85 km height range were computed. An engineering method and design values for gravity wave magnitudes and wave lengths are given to be used for such tasks as evaluating the effects on the dynamical heating, stability and control of spacecraft such as the space shuttle vehicle in launch or reentry trajectories.

MULTI-STRAND CORONAL LOOP MODEL AND FILTER-RATIO ANALYSIS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bourouaine, Sofiane; Marsch, Eckart, E-mail: bourouaine@mps.mpg.d

2010-01-10

We model a coronal loop as a bundle of seven separate strands or filaments. Each of the loop strands used in this model can independently be heated (near their left footpoints) by Alfven/ion-cyclotron waves via wave-particle interactions. The Alfven waves are assumed to penetrate the strands from their footpoints, at which we consider different wave energy inputs. As a result, the loop strands can have different heating profiles, and the differential heating can lead to a varying cross-field temperature in the total coronal loop. The simulation of Transition Region and Coronal Explorer (TRACE) observations by means of this loop modelmore » implies two uniform temperatures along the loop length, one inferred from the 171:195 filter ratio and the other from the 171:284 ratio. The reproduced flat temperature profiles are consistent with those inferred from the observed extreme-ultraviolet coronal loops. According to our model, the flat temperature profile is a consequence of the coronal loop consisting of filaments, which have different temperatures but almost similar emission measures in the cross-field direction. Furthermore, when we assume certain errors in the simulated loop emissions (e.g., due to photometric uncertainties in the TRACE filters) and use the triple-filter analysis, our simulated loop conditions become consistent with those of an isothermal plasma. This implies that the use of TRACE or EUV Imaging Telescope triple filters for observation of a warm coronal loop may not help in determining whether the cross-field isothermal assumption is satisfied or not.« less

Spectral analysis of temperature and Brunt-Vaisala frequency fluctuations observed by radiosondes

NASA Technical Reports Server (NTRS)

Tsuda, T.; Vanzandt, T. E.; Kato, S.; Fukao, S.; Sato, T.

1989-01-01

Recent studies have revealed that vertical wave number spectra of wind velocity and temperture fluctuations in the troposphere and the lower stratosphere are fairly well explained by a saturated gravity wave spectrum. But N(2) (N:Brunt-Vaisala (BV) frequency) spectra seem to be better for testing the scaling of the vertical wave number spectra in layers with different stratifications, beause its energy density is proportional only to the background value of N(2), while that for temperature depends on both the BV frequency and the potential temperature. From temperature profiles observed in June to August 1987 over the MU Observatory, Japan, by using a radiosonde with 30 m height resolution, N(2) spectra are determined in the 2 to 8.5 km (troposphere) and 18.5 to 25 km (lower stratosphere) ranges. Although individual spectra show fairly large day-by-day variability, the slope of the median of 34 spectra agrees reasonably with the theoretical value of -1 in the wave number range of 6 x 10(-4) similar to 3 x 10(-3) (c/m). The ratio of the spectral energy between these two height regions is about equal to the ratio of N(2), consistent with the prediction of saturated gravity wave theory.

Investigation of hurricane Ivan using the coupled ocean-atmosphere-wave-sediment transport (COAWST) model

USGS Publications Warehouse

Zambon, Joseph B.; He, Ruoying; Warner, John C.

2014-01-01

The coupled ocean–atmosphere–wave–sediment transport (COAWST) model is used to hindcast Hurricane Ivan (2004), an extremely intense tropical cyclone (TC) translating through the Gulf of Mexico. Sensitivity experiments with increasing complexity in ocean–atmosphere–wave coupled exchange processes are performed to assess the impacts of coupling on the predictions of the atmosphere, ocean, and wave environments during the occurrence of a TC. Modest improvement in track but significant improvement in intensity are found when using the fully atmosphere–ocean-wave coupled configuration versus uncoupled (e.g., standalone atmosphere, ocean, or wave) model simulations. Surface wave fields generated in the fully coupled configuration also demonstrates good agreement with in situ buoy measurements. Coupled and uncoupled model-simulated sea surface temperature (SST) fields are compared with both in situ and remote observations. Detailed heat budget analysis reveals that the mixed layer temperature cooling in the deep ocean (on the shelf) is caused primarily by advection (equally by advection and diffusion).

Studies of Gravity Waves Using Michelson Interferometer Measurements of OH (3-1) Bands

NASA Astrophysics Data System (ADS)

Won, Young-In; Cho, Young-Min; Lee, Bang Yong; Kim, J.

2001-06-01

As part of a long-term program for polar upper atmospheric studies, temperatures and intensities of the OH (3-1) bands were derived from spectrometric observations of airglow emissions over King Sejong station (62.22o S, 301.25o E). These measurements were made with a Michelson interferometer to cover wavelength regions between 1000 nm and 2000 nm. A spectral analysis was performed to individual nights of data to acquire information on the waves in the upper mesosphere/lower thermosphere. It is assumed that the measured fluctuations in the intensity and temperature of the OH (3-1) airglow were caused by gravity waves propagating through the emission layer. Correlation of intensity and temperature variation revealed oscillations with periods ranging from 2 to 9 hours. We also calculated Krassovsky's parameter and compared with published values.

Heat Wave Changes in the Eastern Mediterranean since 1960

NASA Astrophysics Data System (ADS)

Kuglitsch, Franz G.; Toreti, Andrea; Xoplaki, Elena; Della-Marta, Paul M.; Zerefos, Christos S.; Türkes, Murat; Luterbacher, Jürg

2010-05-01

Heat waves have discernible impacts on mortality and morbidity, infrastructure, agricultural resources, the retail industry, ecosystem and tourism and consequently affect human societies. A new definition of socially relevant heat waves is presented and applied to new data sets of high-quality homogenized daily maximum and minimum summer air temperature series from 246 stations in the eastern Mediterranean region (including Albania, Bosnia-Herzegovina, Bulgaria, Croatia, Cyprus, Greece, Israel, Romania, Serbia, Slovenia, Turkey). Changes in heat wave number, length and intensity between 1960 and 2006 are quantified. Daily temperature homogeneity analysis suggest that many instrumental measurements in the 1960s are warm-biased, correcting for these biases regionally averaged heat wave trends are up to 8% higher. We find significant changes across the western Balkans, southwestern and western Turkey, and along the southern Black Sea coastline. Since the 1960s, the mean heat wave intensity, heat wave length and heat wave number across the eastern Mediterranean region have increased by a factor 7.6 ±1.3, 7.5 ±1.3 and 6.2 ±1.1, respectively. These findings suggest that the heat wave increase in this region is higher than previously reported.

MMAB Operational Products

Science.gov Websites

Atlantic Real-Time Ocean Forecast System NOAA Wavewatch III® Ocean Wave Model Sea Ice Concentration Analysis Satellite Derived Ocean Surface Winds Daily Sea Surface Temperature Analysis Sea Ice Drift Model

Wave number determination of Pc 1-2 mantle waves considering He++ ions: A Cluster study

NASA Astrophysics Data System (ADS)

Grison, B.; Escoubet, C. P.; Santolík, O.; Cornilleau-Wehrlin, N.; Khotyaintsev, Y.

2014-09-01

The present case study concerns narrowband electromagnetic emission detected in the distant cusp region simultaneously with upgoing plasma flows. The wave properties match the usual properties of the Pc 1-2 mantle waves: small angle between the wave vector and the magnetic field line, left-hand polarization, and propagation toward the ionosphere. We report here the first direct wave vector measurement of these waves (about 1.2 × 10- 2 rad/km) through multi spacecraft analysis using the three magnetic components and, at the same time, through single spacecraft analysis based on the refractive index analysis using the three magnetic components and two electric components. The refractive index analysis offers a simple way to estimate wave numbers in this frequency range. Numerical calculations are performed under the observed plasma conditions. The obtained results show that the ion distribution functions are unstable to ion cyclotron instability at the observed wave vector value, due to the large ion temperature anisotropy. We thus show that these electromagnetic ion cyclotron (EMIC) waves are amplified in the distant cusp region. The Poynting flux of the waves is counterstreaming with respect to the plasma flow. This sense of propagation is consistent with the time necessary to amplify the emissions to the observed level. We point out the role of the wave damping at the He++ gyrofrequency to explain that such waves cannot be observed from the ground at the cusp foot print location.

Primordial gravitational waves, precisely: the role of thermodynamics in the Standard Model

NASA Astrophysics Data System (ADS)

Saikawa, Ken'ichi; Shirai, Satoshi

2018-05-01

In this paper, we revisit the estimation of the spectrum of primordial gravitational waves originated from inflation, particularly focusing on the effect of thermodynamics in the Standard Model of particle physics. By collecting recent results of perturbative and non-perturbative analysis of thermodynamic quantities in the Standard Model, we obtain the effective degrees of freedom including the corrections due to non-trivial interaction properties of particles in the Standard Model for a wide temperature interval. The impact of such corrections on the spectrum of primordial gravitational waves as well as the damping effect due to free-streaming particles is investigated by numerically solving the evolution equation of tensor perturbations in the expanding universe. It is shown that the reevaluation of the effects of free-streaming photons and neutrinos gives rise to some additional damping features overlooked in previous studies. We also observe that the continuous nature of the QCD crossover results in a smooth spectrum for modes that reenter the horizon at around the epoch of the QCD phase transition. Furthermore, we explicitly show that the values of the effective degrees of freedom remain smaller than the commonly used value 106.75 even at temperature much higher than the critical temperature of the electroweak crossover, and that the amplitude of primordial gravitational waves at a frequency range relevant to direct detection experiments becomes Script O(1) % larger than previous estimates that do not include such corrections. This effect can be relevant to future high-sensitivity gravitational wave experiments such as ultimate DECIGO. Our results on the temperature evolution of the effective degrees of freedom are made available as tabulated data and fitting functions, which can also be used in the analysis of other cosmological relics.

Fluid flow induced by periodic temperature oscillation over a flat plate: Comparisons with the classical Stokes problems

NASA Astrophysics Data System (ADS)

Pal, Debashis; Chakraborty, Suman

2015-05-01

We delineate the dynamics of temporally and spatially periodic flow over a flat plate originating out of periodic thermoviscous expansion of the fluid, as a consequence of a thermal wave applied on the plate wall. We identify two appropriate length scales, namely, the wavelength of the temperature wave and the thermal penetration depth, so as to bring out the complex thermo-physical interaction between the fluid and the solid boundaries. Our results reveal that the entire thermal fluctuation and the subsequent thermoviscous actuation remain confined within a "thermo-viscous boundary layer." Based on the length scales and the analytical solution for the temperature field, we demarcate three different layers, namely, the wall layer (which is further sub-divided into various sub-layers, based on the temperature field), the intermediate layer, and the outer layer. We show that the interactions between the pressure oscillation and temperature-dependent viscosity yield a unidirectional time-averaged (mean) flow within the wall layer opposite to the direction of motion of the thermal wave. We also obtain appropriate scalings for the time-averaged velocity, which we further substantiate by full scale numerical simulations. Our analysis may constitute a new design basis for simultaneous control of the net throughput and mixing over a solid boundary, by the judicious employment of a traveling temperature wave.

Statistical Analysis of Acoustic Signal Propagating Through the South China Sea Basin

DTIC Science & Technology

2016-03-01

internal tidal constituents are observed in both spectra, and the diurnal (D) and semidiurnal (SD) internal waves ’ energy are strong. The spectrum is...bandwidths were utilized during the frequency smoothing process to ensure the reliability of the spectra in the meso-, tidal and internal wave scale...mooring temperature sensors capture the internal waves ’ energy, and six high amplitude peaks are observed in the spectra in the internal tidal band

Characterization of rarefaction waves in van der Waals fluids

NASA Astrophysics Data System (ADS)

Yuen, Albert; Barnard, John J.

2015-12-01

We calculate the isentropic evolution of an instantaneously heated foil, assuming a van der Waals equation of state with the Maxwell construction. The analysis by Yuen and Barnard [Phys. Rev. E 92, 033019 (2015), 10.1103/PhysRevE.92.033019] is extended for the particular case of three degrees of freedom. We assume heating to temperatures in the vicinity of the critical point. The self-similar profiles of the rarefaction waves describing the evolution of the foil display plateaus in density and temperature due to a phase transition from the single-phase to the two-phase regime. The hydrodynamic equations are expressed in a dimensionless form and the solutions form a set of universal curves, depending on a single parameter: the dimensionless initial entropy. We characterize the rarefaction waves by calculating how the plateau length, density, pressure, temperature, velocity, internal energy, and sound speed vary with dimensionless initial entropy.

Near InfraRed Imaging Spectrograph (NIRIS) for ground-based mesospheric OH(6-2) and O2(0-1) intensity and temperature measurements

NASA Astrophysics Data System (ADS)

Singh, Ravindra P.; Pallamraju, Duggirala

2017-08-01

This paper describes the development of a new Near InfraRed Imaging Spectrograph (NIRIS) which is capable of simultaneous measurements of OH(6-2) Meinel and O2(0-1) atmospheric band nightglow emission intensities. In this spectrographic technique, rotational line ratios are obtained to derive temperatures corresponding to the emission altitudes of 87 and 94 km. NIRIS has been commissioned for continuous operation from optical aeronomy observatory, Gurushikhar, Mount Abu (24.6°N, 72.8°E) since January 2013. NIRIS uses a diffraction grating of 1200 lines mm^{-1} and 1024× 1024 pixels thermoelectrically cooled CCD camera and has a large field-of-view (FOV) of 80° along the slit orientation. The data analysis methodology adopted for the derivation of mesospheric temperatures is also described in detail. The observed NIRIS temperatures show good correspondence with satellite (SABER) derived temperatures and exhibit both tidal and gravity waves (GW) like features. From the time taken for phase propagation in the emission intensities between these two altitudes, vertical phase speed of gravity waves, cz, is calculated and along with the coherent GW time period `τ ', the vertical wavelength, λ z, is obtained. Using large FOV observations from NIRIS, the meridional wavelengths, λ y, are also calculated. We have used one year of data to study the possible cause(s) for the occurrences of mesospheric temperature inversions (MTIs). From the statistics obtained for 234 nights, it appears that in situ chemical heating is mainly responsible for the observed MTIs than the vertical propagation of the waves. Thus, this paper describes a novel near infrared imaging spectrograph, its working principle, data analysis method for deriving OH and O2 emission intensities and the corresponding rotational temperatures at these altitudes, derivation of gravity wave parameters (τ , cz, λ z, and λ y), and results on the statistical study of MTIs that exist in the earth's mesospheric altitudes.

Spatial distribution of temperature trends and extremes over Maharashtra and Karnataka States of India

NASA Astrophysics Data System (ADS)

Dhorde, Amit G.; Korade, Mahendra S.; Dhorde, Anargha A.

2017-10-01

Earth surface temperatures are changing worldwide together with the changes in the extreme temperatures. The present study investigates trends and variations of monthly maximum and minimum temperatures and their effects on seasonal fluctuations at different climatological stations of Maharashtra and Karnataka states of India. Trend analysis was performed on annual and seasonal mean maximum temperature (TMAX) and mean minimum temperature (TMIN) for the period 1969 to 2006. During the last 38 years, an increase in annual TMAX and TMIN has occurred. At most of the locations, the increase in TMAX was faster than the TMIN, resulting in an increase in diurnal temperature range. At the same time, annual mean temperature (TM) showed a significant increase over the study area. Percentiles were used to identify extreme temperature indices. An increase in occurrence of warm extremes was observed at southern locations, and cold extremes increased over the central and northeastern part of the study area. Occurrences of cold wave conditions have decreased rapidly compared to heat wave conditions.

Ionizing gas breakdown waves in strong electric fields.

NASA Technical Reports Server (NTRS)

Klingbeil, R.; Tidman, D. A.; Fernsler, R. F.

1972-01-01

A previous analysis by Albright and Tidman (1972) of the structure of an ionizing potential wave driven through a dense gas by a strong electric field is extended to include atomic structure details of the background atoms and radiative effects, especially, photoionization. It is found that photoionization plays an important role in avalanche propagation. Velocities, electron densities, and temperatures are presented as a function of electric field for both negative and positive breakdown waves in nitrogen.

Variability of the observed temperature, 20-60 km at 80 deg N to 40 deg S

NASA Technical Reports Server (NTRS)

Nastrom, G. D.; Belmont, A. D.; Dartt, D. G.

1974-01-01

Results are presented for a periodic analysis of atmospheric temperature variations at heights of from 20 to 60 km between 80 deg N and 40 deg S. The analysis is based on Meteorological Rocket Network temperatures not corrected for solar radiation or aliasing by the diurnal tide, and the frequencies examined include the long-term mean, the quasi-biennial oscillation (QBO), and the first six harmonics of the annual wave. Amplitudes are plotted for the long-term mean and QBO as well as for the annual, semiannual, and terannual components. The results show two distinct annual oscillations (the high-latitude one and another above the tropical stratopause) and a polar semiannual wave with two centers of large amplitude that are 90 deg out of phase and separated by a zone of minimum amplitude near 45 km.

Multigap superconductivity in the charge density wave superconductor LaPt2Si2

NASA Astrophysics Data System (ADS)

Das, Debarchan; Gupta, Ritu; Bhattacharyya, A.; Biswas, P. K.; Adroja, D. T.; Hossain, Z.

2018-05-01

The superconducting gap structure of a charge density wave (CDW) superconductor LaPt2Si2 (Tc=1.6 K) having a quasi-two-dimensional crystal structure has been investigated using muon spin rotation/relaxation (μ SR ) measurements in transverse field (TF), zero field (ZF), and longitudinal field (LF) geometries. Rigorous analysis of TF-μ SR spectra in the superconducting state corroborates that the temperature dependence of the effective penetration depth, λL, derived from muon spin depolarization, fits to a two gap s wave model (i.e., s +s wave) suggesting that the Fermi surface contains two gaps of different magnitude rather than an isotropic gap expected for a conventional s wave superconductor. On the other hand, ZF μ SR data do not show any significant change in muon spin relaxation rate above and below the superconducting transition temperature indicating the fact that time-reversal symmetry is preserved in the superconducting state of this material.

A comparative analysis of heat waves and associated mortality in St. Louis, Missouri--1980 and 1995.

PubMed

Smoyer, K E

1998-08-01

This research investigates heat-related mortality during the 1980 and 1995 heat waves in St. Louis, Missouri. St. Louis has a long history of extreme summer weather, and heat-related mortality is a public health concern. Heat waves are defined as days with apparent temperatures exceeding 40.6 degrees C (105 degrees F). The study uses a multivariate analysis to investigate the relationship between mortality and heat wave intensity, duration, and timing within the summer season. The heat wave of 1980 was more severe and had higher associated mortality than that of 1995. To learn if changing population characteristics, in addition to weather conditions, contributed to this difference, changes in population vulnerability between 1980 and 1995 are evaluated under simulated heat wave conditions. The findings show that St. Louis remains at risk of heat wave mortality. In addition, there is evidence that vulnerability has increased despite increased air-conditioning penetration and public health interventions.

Comparison of periodic and other characteristics of geomagnetic and meterological rocket data

NASA Technical Reports Server (NTRS)

Nastrom, G. D.; Belmont, A. D.

1976-01-01

The temporal variations in stratospheric winds and temperatures with the geomagnetic field elements were compared. From a periodic analysis of the geomagnetic field elements the amplitude and phase of the quasibiennial, annual, and semiannual waves are given for stations from 1 degree S to 89 degree N. These results are then compared with corresponding waves reported in rocketsonde wind and temperature data. The annual waves are found to be coupled as a result of the annual variation in the dynamo effect of the wind in the lower ionosphere. The semiannual waves are also found to be coupled and three possible causes for the extra tropical stratospheric semiannual wind wave are discussed. Time variance spectra for the interval from 4 days to 44 days in both zonal winds and horizontal geomagnetic field intensity are compared for years when major midwinter warmings occur and years when only minor warmings occur. The noted differences are suggested to arise from upward propagating planetary waves which are absorbed or refracted in varying amounts depending on the prevailing circulation.

Ion-Scale Wave Properties and Enhanced Ion Heating Across the Low-Latitude Boundary Layer During Kelvin-Helmholtz Instability

NASA Astrophysics Data System (ADS)

Moore, T. W.; Nykyri, K.; Dimmock, A. P.

2017-11-01

In the Earth's magnetosphere, the magnetotail plasma sheet ions are much hotter than in the shocked solar wind. On the dawn sector, the cold-component ions are more abundant and hotter by 30-40% when compared to the dusk sector. Recent statistical studies of the flank magnetopause and magnetosheath have shown that the level of temperature asymmetry of the magnetosheath is unable to account for this, so additional physical mechanisms must be at play, either at the magnetopause or plasma sheet that contributes to this asymmetry. In this study, we perform a statistical analysis on the ion-scale wave properties in the three main plasma regimes common to flank magnetopause boundary crossings when the boundary is unstable to Kelvin-Helmholtz instability (KHI): hot and tenuous magnetospheric, cold and dense magnetosheath, and mixed (Hasegawa et al., 2004). These statistics of ion-scale wave properties are compared to observations of fast magnetosonic wave modes that have recently been linked to Kelvin-Helmholtz (KH) vortex centered ion heating (Moore et al., 2016). The statistical analysis shows that during KH events there is enhanced nonadiabatic heating calculated during ion scale wave intervals when compared to non-KH events. This suggests that during KH events there is more free energy for ion-scale wave generation, which in turn can heat ions more effectively when compared to cases when KH waves are absent. This may contribute to the dawn favored temperature asymmetry of the plasma sheet; recent studies suggest KH waves favor the dawn flank during Parker-Spiral interplanetary magnetic field.

Wave-Modulated CO2 Condensation in Mars' Polar Atmosphere From MGS/TES & MOLA and MRO/MCS.

NASA Astrophysics Data System (ADS)

Banfield, D. J.

2016-12-01

In Mars' polar night, atmospheric temperatures fall low enough to cause CO2 condensation. This has been empirically demonstrated by Mars Global Surveyor's (MGS) Mars Orbiter Laser Altimeter (MOLA), which identified reflections from above the surface, and MGS Radio Science (RS) and Thermal Emission Spectrometer (TES) and Mars Reconnaissance Orbiter's (MRO) Mars Climate Sounder (MCS), all of which showed polar night temperature profiles that were super-saturated. Detailed analysis of TES temperature profiles as well as numerical modeling both suggest that the stationary and traveling waves on the polar vortices are strong enough to significantly modulate the CO2 cloud condensation. However the extent to which this is actually occurring has not been quantified. The polar night CO2 condensation represents a significant amount of energy deposition, even if it were uniformly distributed. If instead it is concentrated in the cold sectors of the various waves, this can be a tremendous perturbation not only to the wave amplitudes (clipping them from going much below the CO2 condensation temperature), but also impacting their ability to transport heat and momentum poleward and upward, and thus it may also impact the maintenance and shape of the polar vortex itself. Mars' polar vortices remain barotropically unstable throughout the winter in spite of large amplitude waves in their vicinity. We have identified when and where the various waves (with their specific amplitudes and phases) in the vicinity of the polar vortex should modulate the CO2 condensation (see Figure of a meridional cross-section showing where no clouds are expected (blue), clouds should be ubiquitous (green) and waves should be required to form clouds (red)). We have also correlated this with the distribution of the actual observed cloud identifications from MGS MOLA and MRO MCS. We find only poor correlations between the MGS/TES identified wave modulated condensation predictions and actual simultaneous cloud identifications from MGS/MOLA. We will discuss the results of a similar study using only MRO/MCS to analyze the mean atmospheric temperature, the stationary and traveling waves along the polar vortex, and the actual locations where CO2 condensation is evident.

Evidence of atmospheric gravity wave perturbations of the Brunt-Vaisala frequency in the atmosphere

NASA Technical Reports Server (NTRS)

Good, R. E.; Beland, R. W.; Brown, J. H.; Dewan, E. M.

1986-01-01

A series of high altitude, medium resolution, measurements of temperature, pressure and turbulence have been performed by the Air Force Geophysics Laboratory. These measurements were conducted using the VIZ Manufacturing Co. microsondes with attached micro-thermal probes measuring the temperature structure coefficient. A typical atmospheric temperature measurement is given. Several small temperature inversions are evident in the troposphere. The stratosphere is marked with numerous fluctuations in the temperature profile. Microsondes provide temperature and pressure measurements every 4 seconds up to a maximum altitude of 30 km (MSL). Since the average ascent rate is 5 m/s, the altitude interval between the measurement reports is 20 m. The potential temperature is calculated from the temperature and pressure. Spectral analysis of atmospheric Brunt-Vaisala frequencies reveal spectra similiar to the velocity spectra of Dewan et al. (1984), Daniels (1982), and Endlich and Singleton (1969). The Brunt-Vaisala spectra indicate the existence of separate, distinguishable wave modes.

The Effect of Aerosol on Gravity Wave Characteristics above the Boundary Layer over a Tropical Location

NASA Astrophysics Data System (ADS)

Rakshit, G.; Jana, S.; Maitra, A.

2017-12-01

The perturbations of temperature profile over a location give an estimate of the potential energy of gravity waves propagating through the atmosphere. Disturbances in the lower atmosphere due to tropical deep convection, orographic effects and various atmospheric disturbances generates of gravity waves. The present study investigates the gravity wave energy estimated from fluctuations in temperature profiles over the tropical location Kolkata (22°34' N, 88°22' E). Gravity waves are most intense during the pre-monsoon period (March-June) at the present location, the potential energy having high values above the boundary layer (2-4 km) as observed from radiosonde profiles. An increase in temperature perturbation, due to high ambient temperature in the presence of heat absorbing aerosols, causes an enhancement in potential energy. As the present study location is an urban metropolitan city experiencing high level of pollution, pollutant aerosols can go much above the normal boundary layer during daytime due to convection causing an extended boundary layer. The Aerosol Index (AAI) obtained from Global Ozone Monitoring Experiment-2 (GOME-2) on MetOp-A platform at 340 nm and 380 nm confirms the presence of absorbing aerosol particles over the present location. The Hysplit back trajectory analysis shows that the aerosol particles at those heights are of local origin and are responsible for depleting liquid water content due to cloud burning. The aerosol extinction coefficient obtained from CALIPSO data exhibits an increasing trend during 2006-2016 accompanied by a similar pattern of gravity wave energy. Thus the absorbing aerosols have a significant role in increasing the potential energy of gravity wave at an urban location in the tropical region.

On the detection and attribution of gravity waves generated by the 20 March 2015 solar eclipse

PubMed Central

2016-01-01

Internal gravity waves are generated as adjustment radiation whenever a sudden change in forcing causes the atmosphere to depart from its large-scale balanced state. Such a forcing anomaly occurs during a solar eclipse, when the Moon’s shadow cools part of the Earth’s surface. The resulting atmospheric gravity waves are associated with pressure and temperature perturbations, which in principle are detectable both at the surface and aloft. In this study, surface pressure and temperature data from two UK sites at Reading and Lerwick are examined for eclipse-driven gravity wave perturbations during the 20 March 2015 solar eclipse over northwest Europe. Radiosonde wind data from the same two sites are also analysed using a moving parcel analysis method, to determine the periodicities of the waves aloft. On this occasion, the perturbations both at the surface and aloft are found not to be confidently attributable to eclipse-driven gravity waves. We conclude that the complex synoptic weather conditions over the UK at the time of this particular eclipse helped to mask any eclipse-driven gravity waves. This article is part of the themed issue ‘Atmospheric effects of solar eclipses stimulated by the 2015 UK eclipse’. PMID:27550763

On the detection and attribution of gravity waves generated by the 20 March 2015 solar eclipse.

PubMed

Marlton, G J; Williams, P D; Nicoll, K A

2016-09-28

Internal gravity waves are generated as adjustment radiation whenever a sudden change in forcing causes the atmosphere to depart from its large-scale balanced state. Such a forcing anomaly occurs during a solar eclipse, when the Moon's shadow cools part of the Earth's surface. The resulting atmospheric gravity waves are associated with pressure and temperature perturbations, which in principle are detectable both at the surface and aloft. In this study, surface pressure and temperature data from two UK sites at Reading and Lerwick are examined for eclipse-driven gravity wave perturbations during the 20 March 2015 solar eclipse over northwest Europe. Radiosonde wind data from the same two sites are also analysed using a moving parcel analysis method, to determine the periodicities of the waves aloft. On this occasion, the perturbations both at the surface and aloft are found not to be confidently attributable to eclipse-driven gravity waves. We conclude that the complex synoptic weather conditions over the UK at the time of this particular eclipse helped to mask any eclipse-driven gravity waves.This article is part of the themed issue 'Atmospheric effects of solar eclipses stimulated by the 2015 UK eclipse'. © 2016 The Authors.

A biometeorology study of climate and heat-related morbidity in Phoenix from 2001 to 2006

NASA Astrophysics Data System (ADS)

Golden, Jay S.; Hartz, Donna; Brazel, Anthony; Luber, George; Phelan, Patrick

2008-07-01

Heat waves kill more people in the United States than hurricanes, tornadoes, earthquakes, and floods combined. Recently, international attention focused on the linkages and impacts of human health vulnerability to urban climate when Western Europe experienced over 30,000 excess deaths during the heat waves of the summer of 2003—surpassing the 1995 heat wave in Chicago, Illinois, that killed 739. While Europe dealt with heat waves, in the United States, Phoenix, Arizona, established a new all-time high minimum temperature for the region on July 15, 2003. The low temperature of 35.5°C (96°F) was recorded, breaking the previous all-time high minimum temperature record of 33.8°C (93°F). While an extensive literature on heat-related mortality exists, greater understanding of influences of heat-related morbidity is required due to climate change and rapid urbanization influences. We undertook an analysis of 6 years (2001 2006) of heat-related dispatches through the Phoenix Fire Department regional dispatch center to examine temporal, climatic and other non-spatial influences contributing to high-heat-related medical dispatch events. The findings identified that there were no significant variations in day-of-week dispatch events. The greatest incidence of heat-related medical dispatches occurred between the times of peak solar irradiance and maximum diurnal temperature, and during times of elevated human comfort indices (combined temperature and relative humidity).

A biometeorology study of climate and heat-related morbidity in Phoenix from 2001 to 2006.

PubMed

Golden, Jay S; Hartz, Donna; Brazel, Anthony; Luber, George; Phelan, Patrick

2008-07-01

Heat waves kill more people in the United States than hurricanes, tornadoes, earthquakes, and floods combined. Recently, international attention focused on the linkages and impacts of human health vulnerability to urban climate when Western Europe experienced over 30,000 excess deaths during the heat waves of the summer of 2003-surpassing the 1995 heat wave in Chicago, Illinois, that killed 739. While Europe dealt with heat waves, in the United States, Phoenix, Arizona, established a new all-time high minimum temperature for the region on July 15, 2003. The low temperature of 35.5 degrees C (96 degrees F) was recorded, breaking the previous all-time high minimum temperature record of 33.8 degrees C (93 degrees F). While an extensive literature on heat-related mortality exists, greater understanding of influences of heat-related morbidity is required due to climate change and rapid urbanization influences. We undertook an analysis of 6 years (2001-2006) of heat-related dispatches through the Phoenix Fire Department regional dispatch center to examine temporal, climatic and other non-spatial influences contributing to high-heat-related medical dispatch events. The findings identified that there were no significant variations in day-of-week dispatch events. The greatest incidence of heat-related medical dispatches occurred between the times of peak solar irradiance and maximum diurnal temperature, and during times of elevated human comfort indices (combined temperature and relative humidity).

Mesospheric Temperature Measurements over Scandinavia During the Gravity Wave Life Cycle Campaign (GW-LCYCLE)

NASA Astrophysics Data System (ADS)

Pautet, P. D.; Taylor, M.; Kaifler, B.

2016-12-01

The Gravity Wave Life Cycle (GW-LCYCLE) project took place in Northern Scandinavia during the winter 2015-16. This international program focused on investigating the generation and deep propagation of atmospheric gravity waves, especially the orographic waves generated over the Scandinavian mountain range. A series of instruments was operated at several ground-based locations and on-board the DLR HALO Gulfstream V and Falcon aircrafts. As part of this project, Utah State University (USU) deployed 3 Advanced Mesospheric Temperature Mappers (AMTM) at the ALOMAR facility, Norway (operational since December 2010), at the IRF institute in Kiruna, Sweden, and at the FMI institute in Sodankylä, Finland. Each of these instruments measures the OH (3,1) rotational temperature over a large region (200x160km) at 87km altitude. During the campaign, their total coverage extended across the Scandinavian Mountain Range, from the wind side in the west to 500 km to the east in the lee of the mountains, allowing the investigation of the occurrence and evolution of gravity waves (GWs) over this part of Scandinavia. Furthermore, the AMTM in Sodankylä operated in the container housing a DLR Rayleigh lidar. Both instruments ran simultaneously and autonomously from November 2015 to April 2016, providing an unprecedented complementary high-quality data set. This presentation will introduce preliminary results obtained during this campaign, in particular the evolution of the mesospheric temperature through the winter, the analysis of mountain waves occurrence and dynamics at mesospheric altitude, as well as the investigation of interesting individual GW cases.

Evolution of wave patterns and temperature field in shock-tube flow

NASA Astrophysics Data System (ADS)

Kiverin, A. D.; Yakovenko, I. S.

2018-05-01

The paper is devoted to the numerical analysis of wave patterns behind a shock wave propagating in a tube filled with a gaseous mixture. It is shown that the flow inside the boundary layer behind the shock wave is unstable, and the way the instability develops fully corresponds to the solution obtained for the boundary layer over a flat plate. Vortical perturbations inside the boundary layer determine the nonuniformity of the temperature field. In turn, exactly these nonuniformities define the way the ignition kernels arise in the combustible mixture after the reflected shock interaction with the boundary layer. In particular, the temperature nonuniformity determines the spatial limitations of probable ignition kernel position relative to the end wall and side walls of the tube. In the case of low-intensity incident shocks the ignition could start not farther than the point of first interaction between the reflected shock wave and roller vortices formed in the process of boundary layer development. Proposed physical mechanisms are formulated in general terms and can be used for interpretation of the experimental data in any systems with a delayed exothermal reaction start. It is also shown that contact surface thickening occurs due to its interaction with Tollmien-Schlichting waves. This conclusion is of importance for understanding the features of ignition in shock tubes operating in the over-tailored regime.

Investigation of Tropical Dynamics and Transport with UARS Data

NASA Technical Reports Server (NTRS)

Jackman, Charles (Technical Monitor); Dunkerton, Timothy J.; Mote, Philip W.

2003-01-01

Our research focused on Kelvin waves in the tropical lower stratosphere, and resulted in three papers published or submitted to the Journal of Geophysical Research. The first of these, published in 2002, used temperature data from the Microwave Limb Sounder to examine the amplitude, frequency, phase, and spatial structure of leading modes of Kelvin waves. The second and third, submitted late in 2002 and currently in revision, described the response to Kelvin waves of various trace constituents measured by MLS and CLAES (methane, nitrous oxide, CFC-12, and ozone in the second paper; water vapor in the third paper). Water vapor is a special case because the vertical structure induced by Kelvin waves is convolved with water vapor's seasonally varying vertical profile induced by seasonal variations in temperature at the tropical tropopause. Forward modeling indicated that the vertical resolution of MLS was indeed adequate to capture this complicated structure, yet it was not visible in the MLS data, though the Kelvin wave signature was clear on certain UARS levels. The effects of Kelvin waves on the tropical tropopause and on stratosphere- troposphere exchange cannot be quantified from UARS data because of poor vertical resolution and sensitivity in that region. It is recommended that this analysis be repeated using data from the new MLS and HIRDLS instruments aboard Aura, and that priority be given to fine-scale retrievals of temperature, water vapor, and ozone in the tropical tropopause region.

Ablation behaviors of carbon reinforced polymer composites by laser of different operation modes

NASA Astrophysics Data System (ADS)

Wu, Chen-Wu; Wu, Xian-Qian; Huang, Chen-Guang

2015-10-01

Laser ablation mechanism of Carbon Fiber Reinforced Polymer (CFRP) composite is of critical meaning for the laser machining process. The ablation behaviors are investigated on the CFRP laminates subject to continuous wave, long duration pulsed wave and short duration pulsed wave lasers. Distinctive ablation phenomena have been observed and the effects of laser operation modes are discussed. The typical temperature patterns resulted from laser irradiation are computed by finite element analysis and thereby the different ablation mechanisms are interpreted.

Langmuir wave phase-mixing in warm electron-positron-dusty plasmas

NASA Astrophysics Data System (ADS)

Pramanik, Sourav; Maity, Chandan

2018-04-01

An analytical study on nonlinear evolution of Langmuir waves in warm electron-positron-dusty plasmas is presented. The massive dust grains of either positively or negatively charged are assumed to form a fixed charge neutralizing background. A perturbative analysis of the fluid-Maxwell's equations confirms that the excited Langmuir waves phase-mix and eventually break, even at arbitrarily low amplitudes. It is shown that the nature of the dust-charge as well as the amount of dust grains can significantly influence the Langmuir wave phase-mixing process. The phase-mixing time is also found to increase with the temperature.

A novel approach for detecting heat waves: the Standardized Heat-Wave Index.

NASA Astrophysics Data System (ADS)

Cucchi, Marco; Petitta, Marcello; Calmanti, Sandro

2016-04-01

Extreme temperatures have an impact on the energy balance of any living organism and on the operational capabilities of critical infrastructures. The ability to capture the occurrence of extreme temperature events is therefore an essential property of a multi-hazard extreme climate indicator. In this paper we introduce a new index for the detection of such extreme temperature events called SHI (Standardized Heat-Wave Index), developed in the context of XCF project for the construction of a multi-hazard extreme climate indicator (ECI). SHI is a probabilistic index based on the analysis of maximum daily temperatures time series; it is standardized, enabling comparisons overs space/time and with other indices, and it is capable of describing both extreme cold and hot events. Given a particular location, SHI is constructed using the time series of local maximum daily temperatures with the following procedure: three-days cumulated maximum daily temperatures are assigned to each day of the time series; probabilities of occurrence in the same months the reference days belong to are computed for each of the previous calculated values; such probability values are thus projected on a standard normal distribution, obtaining our standardized indices. In this work we present results obtained using NCEP Reanalysis dataset for air temperature at sigma 0.995 level, which timespan ranges from 1948 to 2014. Given the specific framework of this work, the geographical focus of this study is limited to the African continent. We present a validation of the index by showing its use for monitoring heat-waves under different climate regimes.

The Resistance to Deformation and Facture of Magnesium MA2-1 Under Shock-Wave Loading at 293 K and 823 K of the Temperature

NASA Astrophysics Data System (ADS)

Garkushin, Gennady; Kanel, Gennady; Razorenov, Sergey

2011-06-01

The spall strength and elastic-plastic response have been measured with the VISAR for MA2-1 (94.2% Mg, 0.4 % Mn, 4.4% Al, 1% Zn) alloy at temperatures from 293 K to 823 K. The decay of elastic precursor wave at 293 K is approximately in reverse proportionality with the cubic root from the distance that corresponds to decrease of plastic strain rate from 5 ×105 s-1 at 0.25 mm (213 MPa of the shear stress) down to 5 ×103 s-1 at 10 mm (63 MPa shear stress). An analysis of the rise times of plastic shock waves shows by order of magnitude faster plastic strain rates at corresponding shear stresses than that at the HEL. The decay of elastic precursor wave is weaker and the dependence of initial plastic strain rate on the shear stress at HEL is stronger than that was observed for aluminum. Unlike to aluminum, the magnesium alloy does not exhibit anomalous thermal hardening: the HEL values at 823 K are close to the values at room temperatures. The temperature increase from 293 K to 823 K has led to significant decrease of the spall strength.

The contribution of wind wave changes on diminishing ice period in Lake Pyhäjärvi during the last half-century.

PubMed

Wu, Tingfeng; Qin, Boqiang; Zhu, Guangwei; Huttula, Timo; Lindfors, Antti; Ventelä, Anne-Mari; Sheng, Yongwei; Ambrose, Richard F

2018-06-21

To address the contribution of long-term wind wave changes on diminishing ice period in Northern European lakes, an in situ observation of wind waves was conducted to calibrate a wind-wave numerical model for Lake Pyhäjärvi, which is the largest lake in southwest Finland. Using station-measured hydrometeorological data from 1963 to 2013 and model-simulated wind waves, correlation and regression analyses were conducted to assess the changing trend and main influences on ice period. Ice period in Lake Pyhäjärvi decreased significantly over 51 years (r = 0.47, P < 0.01). The analysis of main hydrometeorological factors to ice period showed that the significant air temperature rise is the main contributor for the diminishing of ice period in the lake. Besides air temperature, wind-induced waves can also weaken lake ice by increasing water mixing and lake ice breakage. The regression indicated that mean significant wave height in December and April was negatively related to ice period (r = - 0.48, P < 0.01). These results imply that long-term changes of wind waves related to climate change should be considered to fully understand the reduction of aquatic ice at high latitudes.

Density and temperature structure over northern Europe

NASA Technical Reports Server (NTRS)

Philbrick, C. R.; Schmidlin, F. J.; Grossmann, K. U.; Lange, G.; Offermann, D.; Baker, K. D.; Krankowsky, D.; Von Zahn, U.

1985-01-01

During the Energy Budget Campaign, a number of profiles of the density and temperature were obtained to study the structure and variability of the atmosphere. The measurements were made using rocketborne instrumentation launched from Esrange, Sweden, and Andoya Rocket Range, Norway, during November and December 1980. The techniques included meteorological temperature sondes, passive falling sphere, accelerometer instrumented falling spheres, density gauges, mass spectrometers and infrared emission experiments. The instruments provided data covering the altitude range from 20 to 150 km. The measurements were made during periods which have been grouped into three categories by level of geomagnetic activity. Analysis has been made to compare the results and to examine the wave features and variations in the vertical profiles for scales ranging between hundreds of meters and tens of kilometers. Most of the features observed fit qualitatively within the range expected for internal gravity waves. However, the features in the profiles during one of the measurement periods are unusual and may be due to aurorally generated shock waves. The geomagnetic storm conditions caused temperature increases in the lower thermosphere which maximized in the 120-140 km region.

A Study of Surface Temperatures, Clouds and Net Radiation

NASA Technical Reports Server (NTRS)

Dhuria, Harbans

1996-01-01

This study focused on the seasonal relationships and interactions of climate parameters such as the surface temperatures, net radiation, long wave flux, short wave flux, and clouds on a global basis. Five years of observations (December 1984 to November 1989) from the Earth Radiation Budget Experiment (ERBE) and the International Satellite Cloud Climatology Program (ISCCP) were used to study both seasonal variations and interannual variations by use of a basic radiation budget equation. In addition, the study was extended to include an analysis of the cloud forcing due El-Nino's impact on the ERBE parameters.

Effects of Simulated Heat Waves with Strong Sudden Cooling Weather on ApoE Knockout Mice

PubMed Central

Zhang, Shuyu; Kuang, Zhengzhong; Zhang, Xiakun

2015-01-01

This study analyzes the mechanism of influence of heat waves with strong sudden cooling on cardiovascular diseases (CVD) in ApoE−/− mice. The process of heat waves with strong sudden cooling was simulated with a TEM1880 meteorological-environment simulation chamber according to the data obtained at 5 a.m. of 19 June 2006 to 11 p.m. of 22 June 2006. Forty-eight ApoE−/− mice were divided into six blocks based on their weight. Two mice from each block were randomly assigned to control, heat wave, temperature drop, and rewarming temperature groups. The experimental groups were transferred into the climate simulator chamber for exposure to the simulated heat wave process with strong sudden temperature drop. After 55, 59, and 75 h of exposure, the experimental groups were successively removed from the chamber to monitor physiological indicators. Blood samples were collected by decollation, and the hearts were harvested in all groups. The levels of heat stress factors (HSP60, SOD, TNF, sICAM-1, HIF-1α), cold stress factors (NE, EPI), vasoconstrictor factors (ANGII, ET-1, NO), and four items of blood lipid (TC, TG, HDL-C, and LDL-C) were measured in each ApoE−/− mouse. Results showed that the heat waves increased the levels of heat stress factors except SOD decreased, and decreased the levels of vasoconstrictor factors and blood lipid factors except TC increased. The strong sudden temperature drop in the heat wave process increased the levels of cold stress factors, vasoconstrictor factors and four blood lipid items (except the level of HDL-C which decreased) and decreased the levels of heat stress factors (except the level of SOD which increased). The analysis showed that heat waves could enhance atherosclerosis of ApoE−/− mice. The strong sudden temperature drop during the heat wave process increased the plasma concentrations of NE and ANGII, which indicates SNS activation, and resulted in increased blood pressure. NE and ANGII are vasoconstrictors involved in systemic vasoconstriction especially in the superficial areas of the body and conducive to increased blood pressure. The increase in the blood lipid levels of TG, LDL-C, TC, and LDL-C/HDL-C further aggravated CVD. This paper explored the influence mechanism of the heat waves with sudden cooling on CVD in ApoE−/− mice. PMID:26016434

Effects of Simulated Heat Waves with Strong Sudden Cooling Weather on ApoE Knockout Mice.

PubMed

Zhang, Shuyu; Kuang, Zhengzhong; Zhang, Xiakun

2015-05-26

This study analyzes the mechanism of influence of heat waves with strong sudden cooling on cardiovascular diseases (CVD) in ApoE-/- mice. The process of heat waves with strong sudden cooling was simulated with a TEM1880 meteorological-environment simulation chamber according to the data obtained at 5 a.m. of 19 June 2006 to 11 p.m. of 22 June 2006. Forty-eight ApoE-/- mice were divided into six blocks based on their weight. Two mice from each block were randomly assigned to control, heat wave, temperature drop, and rewarming temperature groups. The experimental groups were transferred into the climate simulator chamber for exposure to the simulated heat wave process with strong sudden temperature drop. After 55, 59, and 75 h of exposure, the experimental groups were successively removed from the chamber to monitor physiological indicators. Blood samples were collected by decollation, and the hearts were harvested in all groups. The levels of heat stress factors (HSP60, SOD, TNF, sICAM-1, HIF-1α), cold stress factors (NE, EPI), vasoconstrictor factors (ANGII, ET-1, NO), and four items of blood lipid (TC, TG, HDL-C, and LDL-C) were measured in each ApoE-/- mouse. Results showed that the heat waves increased the levels of heat stress factors except SOD decreased, and decreased the levels of vasoconstrictor factors and blood lipid factors except TC increased. The strong sudden temperature drop in the heat wave process increased the levels of cold stress factors, vasoconstrictor factors and four blood lipid items (except the level of HDL-C which decreased) and decreased the levels of heat stress factors (except the level of SOD which increased). The analysis showed that heat waves could enhance atherosclerosis of ApoE-/- mice. The strong sudden temperature drop during the heat wave process increased the plasma concentrations of NE and ANGII, which indicates SNS activation, and resulted in increased blood pressure. NE and ANGII are vasoconstrictors involved in systemic vasoconstriction especially in the superficial areas of the body and conducive to increased blood pressure. The increase in the blood lipid levels of TG, LDL-C, TC, and LDL-C/HDL-C further aggravated CVD. This paper explored the influence mechanism of the heat waves with sudden cooling on CVD in ApoE-/- mice.

Climate change induced heat wave hazard in eastern Africa: Dar Es Salaam (Tanzania) and Addis Ababa (Ethiopia) case study

NASA Astrophysics Data System (ADS)

Capuano, Paolo; Sellerino, Mariangela; Di Ruocco, Angela; Kombe, Wilbard; Yeshitela, Kumelachew

2013-04-01

Last decades, new records were set in the world for tornadoes, drought, wind, floods, wildfires and hot temperatures, testifying unusual weather and climate patterns with increasing frequency and intensity of extreme weather events. Extreme heat events are natural hazards affecting many regions in the world, nevertheless limited work has been done on the analysis and effects of extreme heat events in Africa, that is considered a continent particularly vulnerable to the effects of climate change. In fact, the increase of temperature expected in the African continent during the 21st century is larger than the global mean warming, being about 3° to 4° C, about 1.5 times the global temperature increase (Christensen et al., 2007; Gualdi et al., 2012), with the subtropical regions projected to warm more than the tropical regions. Observations and downscaled model simulations (RCP4.5 and RCP8.5 IPCC scenarios) are analyzed to describe heat wave characteristics in Dar es Salaam (Tanzania) and Addis Ababa (Ethiopia), spanning the last five decades as well as that projected for the 21st century. Observed data are daily maximum and minimum temperature collected in the period 1961-2011; downscaled model simulations span up to 2050. Heat waves are defined following a peak over threshold approach by statistical comparison to historical meteorological baselines (site dependent), using a fixed absolute threshold. Projected future warming in the Dar es Salaam and Addis Ababa shows a further increase in the heat waves parameters. Heat wave duration and hot days number are strictly correlated showing that the temperature rise could generate not only an increase of heat waves number but mainly a longer average duration, that can strongly affect the resilience capacity of the population, particularly the elder people. In fact, the impacts of heat waves on the society are determined also by temporal duration (Stephenson, 2008), in addition to their frequency, in fact the capacity of adaptation can be reduced with prolonged exposure to high temperature and humidity. The expected persistence of long-lived heat waves lasting approximately 1.5-2 weeks is clearly longer with respect to the climatological period (1961-1990). During 100 years, short lived but more intense waves are more than doubled in duration. It is evident the needs for the national health services to develop strategies for the mitigation of the heat wave effects, to enhance the resilience of the population, particularly the elder people.

Warm Season Subseasonal Variability and Climate Extremes in the Northern Hemisphere: The Role of Stationary Rossby Waves

NASA Technical Reports Server (NTRS)

Schubert, Siegfried; Wang, Hailan; Suarez, Max

2010-01-01

This study examines the nature of boreal summer subseasonal atmospheric variability based on the new NASA Modern-Era Retrospective analysis for Research and Applications (MERRA) for the period 1979-2010. An analysis of the June, July and August subseasonal 250hPa v-wind anomalies shows distinct Rossby wave-like structures that appear to be guided by the mean jets. On monthly subseasonal time scales, the leading waves (the first 10 rotated empirical orthogonal functions or REOFs of the 250hPa v-wind) explain about 50% of the Northern Hemisphere vwind variability, and account for more than 30% (60%) of the precipitation (surface temperature) variability over a number of regions of the northern middle and high latitudes, including the U.S. northern Great Plains, parts of Canada, Europe, and Russia. The first REOF in particular, consists of a Rossby wave that extends across northern Eurasia where it is a dominant contributor to monthly surface temperature and precipitation variability, and played an important role in the 2003 European and 2010 Russian heat waves. While primarily subseasonal in nature, the Rossby waves can at times have a substantial seasonal mean component. This is exemplified by REOF 4 which played a major role in the development of the most intense anomalies of the U.S. 1988 drought (during June) and the 1993 flooding (during July), though differed in the latter event by also making an important contribution to the seasonal mean anomalies. A stationary wave model (SWM) is used to reproduce some of the basic features of the observed waves and provide insight into the nature of the forcing. In particular, the responses to a set of idealized forcing functions are used to map the optimal forcing patterns of the leading waves. Also, experiments to reproduce the observed waves with the SWM using MERRA-based estimates of the forcing indicate that the wave forcing is dominated by sub-monthly vorticity transients.

Gravity wave momentum flux estimation from CRISTA satellite data

NASA Astrophysics Data System (ADS)

Ern, M.; Preusse, P.; Alexander, M. J.; Offermann, D.

2003-04-01

Temperature altitude profiles measured by the CRISTA satellite were analyzed for gravity waves (GWs). Amplitudes, vertical and horizontal wavelengths of GWs are retrieved by applying a combination of maximum entropy method (MEM) and harmonic analysis (HA) to the temperature height profiles and subsequently comparing the so retrieved GW phases of adjacent altitude profiles. From these results global maps of the absolute value of the vertical flux of horizontal momentum have been estimated. Significant differences between distributions of the temperature variance and distributions of the momentum flux exist. For example, global maps of the momentum flux show a pronounced northward shift of the equatorial maximum whereas temperature variance maps of the tropics/subtropics are nearly symmetric with respect to the equator. This indicates the importance of the influence of horizontal and vertical wavelength distribution on global structures of the momentum flux.

Introduction and analysis of several FY3C-MWHTS cloud/rain screening methods

NASA Astrophysics Data System (ADS)

Li, Xiaoqing

2017-04-01

Data assimilation of satellite microwave sounders are very important for numerical weather prediction. Fengyun-3C (FY-3C),launched in September, 2013, has two such sounders: MWTS (MicroWave Temperature Sounder) and MWHTS (MicroWave Humidity and Temperature Sounder). These data should be quality-controlled before assimilation and cloud/rain detection is one of the crucial steps. This paper introduced different cloud/rain detection methods based on MWHTS, VIRR (Visible and InfraRed Radiometer) and MWRI (Microwave Radiation Imager) observations. We designed 6 cloud/rain detection combinations and then analyzed the application effect of these schemes. The difference between observations and model simulations for FY-3C MWHTS channels were calculated as a parameter for analysis. Both RTTOV and CRTM were used to fast simulate radiances of MWHTS channels.

Wave rotor-enhanced gas turbine engines

NASA Technical Reports Server (NTRS)

Welch, Gerard E.; Scott, Jones M.; Paxson, Daniel E.

1995-01-01

The benefits of wave rotor-topping in small (400 to 600 hp-class) and intermediate (3000 to 4000 hp-class) turboshaft engines, and large (80,000 to 100,000 lb(sub f)-class) high bypass ratio turbofan engines are evaluated. Wave rotor performance levels are calculated using a one-dimensional design/analysis code. Baseline and wave rotor-enhanced engine performance levels are obtained from a cycle deck in which the wave rotor is represented as a burner with pressure gain. Wave rotor-toppings is shown to significantly enhance the specific fuel consumption and specific power of small and intermediate size turboshaft engines. The specific fuel consumption of the wave rotor-enhanced large turbofan engine can be reduced while operating at significantly reduced turbine inlet temperature. The wave rotor-enhanced engine is shown to behave off-design like a conventional engine. Discussion concerning the impact of the wave rotor/gas turbine engine integration identifies tenable technical challenges.

Sustainability of Smart Cities under Climate Variability and Climate Change in India

NASA Astrophysics Data System (ADS)

Kumar, R.; Mishra, V.

2015-12-01

India has experienced a rapid urbanization during the past few decades. On the other hand, many parts of the country witnessed significant changes in mean and extreme climate related to precipitation and temperature. Here we analysed urban residence using the remotely sensed data considering the susceptibility of Indian cities to droughts and heat waves. We selected recently announced 100 urban areas that are planned to be developed as smart cities in future. Gridded precipitation data were used to compute SPEI values for frequency and ascertain the extent of droughts in the cities. The heat wave analysis was done in two phases. First phase included analysis using Heat Wave Magnitude Index (HWMI) to determine the intensity of such extreme events. In the second phase, Urban Heat Island (UHI) effect across different ecological configuration was studied for the cities. Land Surface Temperature (LST), urban extent map from MODIS and land-cover maps were used to study the UHI effect. For this, the urban extents were divided into urban core and sub-urban zones based on built up regions in the cities. The urban to rural temperature difference is analysed considering the ecological configuration in the region. The selected cities were categorised based on the biome features surrounding them. The results suggest aggravated condition in the urban space in India with reference to extreme events. For instance, extreme heat waves have substantially increased in India during the last few decades. In many urban areas, the UHI effect contributed a significant warming due to increased urbanization. We estimated projected changes in droughts and heat waves in the selected urban areas using the dynamically downscaled data from the region climate models. Our results suggest that a majority of urban areas are projected to face an elevated risk of temperature related extremes and issues of water sustainability in the coming decades.

Mesoscale Variability in SUCCESS Data

NASA Technical Reports Server (NTRS)

Eckermann, Stephen D.; Stewart, Richard W. (Technical Monitor)

1998-01-01

Analysis of meteorological, chemical and microphysical data from the airborne SUCCESS (SUbsonic aircraft Contrail and Cloud Effects Special Study) mission is reported. Careful analysis of the complex DC-8 flight pattern of May 2, 1996 reveals 19 linear flight segments within six main geographical areas, which we have analyzed. Significant mountain wave activity is revealed in the data from the MMS (Meteorology Measurement System) and MTP (Microwave Temperature Profiler) instruments on the DC-8, which resembles previous observations of mountain wave structures near Boulder, Colorado. Strong mountain-wave-induced upwelling downwind of the Rockies is noted. Turbulence is also noted in regions of the mountain wave consistent with overturning near the tropopause. Zonal winds recorded on the ER-2 are shown to be consistent with mountain wave breaking at or near critical levels in the stratosphere, consistent with the strong turbulence reported by the pilot during the ER-2 flight. These observations have been supported with spectral analyses and modeling studies. 'Postcasts' of mountain wave activity on May 2, 1996 using the Naval Research Laboratory Mountain Wave Forecast Model predicts both strong mountain wave activity near the tropopause and strong mountain-wave-induced turbulence in the stratosphere.

Heat-Related Mortality in India: Excess All-Cause Mortality Associated with the 2010 Ahmedabad Heat Wave

PubMed Central

Azhar, Gulrez Shah; Mavalankar, Dileep; Nori-Sarma, Amruta; Rajiva, Ajit; Dutta, Priya; Jaiswal, Anjali; Sheffield, Perry; Knowlton, Kim; Hess, Jeremy J.; Azhar, Gulrez Shah; Deol, Bhaskar; Bhaskar, Priya Shekhar; Hess, Jeremy; Jaiswal, Anjali; Khosla, Radhika; Knowlton, Kim; Mavalankar, Mavalankar; Rajiva, Ajit; Sarma, Amruta; Sheffield, Perry

2014-01-01

Introduction In the recent past, spells of extreme heat associated with appreciable mortality have been documented in developed countries, including North America and Europe. However, far fewer research reports are available from developing countries or specific cities in South Asia. In May 2010, Ahmedabad, India, faced a heat wave where the temperatures reached a high of 46.8°C with an apparent increase in mortality. The purpose of this study is to characterize the heat wave impact and assess the associated excess mortality. Methods We conducted an analysis of all-cause mortality associated with a May 2010 heat wave in Ahmedabad, Gujarat, India, to determine whether extreme heat leads to excess mortality. Counts of all-cause deaths from May 1–31, 2010 were compared with the mean of counts from temporally matched periods in May 2009 and 2011 to calculate excess mortality. Other analyses included a 7-day moving average, mortality rate ratio analysis, and relationship between daily maximum temperature and daily all-cause death counts over the entire year of 2010, using month-wise correlations. Results The May 2010 heat wave was associated with significant excess all-cause mortality. 4,462 all-cause deaths occurred, comprising an excess of 1,344 all-cause deaths, an estimated 43.1% increase when compared to the reference period (3,118 deaths). In monthly pair-wise comparisons for 2010, we found high correlations between mortality and daily maximum temperature during the locally hottest “summer” months of April (r = 0.69, p<0.001), May (r = 0.77, p<0.001), and June (r = 0.39, p<0.05). During a period of more intense heat (May 19–25, 2010), mortality rate ratios were 1.76 [95% CI 1.67–1.83, p<0.001] and 2.12 [95% CI 2.03–2.21] applying reference periods (May 12–18, 2010) from various years. Conclusion The May 2010 heat wave in Ahmedabad, Gujarat, India had a substantial effect on all-cause excess mortality, even in this city where hot temperatures prevail through much of April-June. PMID:24633076

Numerical simulation and analysis of impact of non-orographic gravity waves drag of middle atmosphere in framework of a general circulation model

NASA Astrophysics Data System (ADS)

Zhao, J.; Wang, S.

2017-12-01

Gravity wave drag (GWD) is among the drivers of meridional overturning in the middle atmosphere, also known as the Brewer-Dobson Circulation, and of the quasi-biennial oscillation (QBO). The small spatial scales and complications due to wave breaking require their effects to be parameterised. GWD parameterizations are usually divided into two parts, orographic and non-orographic. The basic dynamical and physical processes of the middle atmosphere and the mechanism of the interactions between the troposphere and the middle atmosphere were studied in the frame of a general circulation model. The model for the troposphere was expanded to a global model considering middle atmosphere with the capability of describing the basic processes in the middle atmosphere and the troposphere-middle atmosphere interactions. Currently, it is too costly to include full non-hydrostatic and rotational wave dynamics in an operational parameterization. The hydrostatic non-rotational wave dynamics which allow an efficient implementation that is suitably fast for operation. The simplified parameterization of non-orographic GWD follows from the WM96 scheme in which a framework is developed using conservative propagation of gravity waves, critical level filtering, and non-linear dissipation. In order to simulate and analysis the influence of non-orographic GWD on the stratospheric wind and temperature fields, experiments using Stratospheric Sudden Warming (SSW) event case occurred in January 2013 were carried out, and results of objective weather forecast verifications of the two months period were compared in detail. The verification of monthly mean of forecast anomaly correlation (ACC) and root mean square (RMS) errors shows consistently positive impact of non-orographic GWD on skill score of forecasting for the three to eight days, both in the stratosphere and troposphere, and visible positive impact on prediction of the stratospheric wind and temperature fields. Numerical simulation during SSW event demonstrates that the influence on the temperature of middle stratosphere is mainly positive and there were larger departure both for the wind and temperature fields considering the non-orographic GWD during the warming process.

Response of a semiconducting infinite medium under two temperature theory with photothermal excitation due to laser pulses

NASA Astrophysics Data System (ADS)

Lotfy, Kh.; Gabr, M. E.

2017-12-01

A novel model of two-dimensional deformations for two-temperature theory at the free surface under the excitation of thermoelastic wave by pulsed laser for a semi-infinite semiconducting medium is studied. The effect of mechanical force during a photothermal process is investigated. The mathematical methods of the Lord-Shulman (LS includes one relaxation time) and Green-Lindsay (GL with two relaxation times) theories as well as the classical dynamical coupled theory (CD) are used. An exact expression for displacement components, force stresses, carrier density and distribution of temperature are obtained using the harmonic wave analysis. Combinations of two-temperature and photothermal theories are obtained analytically. Comparisons of the results are made between the three theories also. The effects of thermoelectric coupling parameter, two-temperature parameter on the displacement component, force stress, carrier density, and distribution of temperature for silicon (Si) medium have been illustrated graphically. The variations of the considered variables with the horizontal distance have been discussed.

Elastic Wave Velocity Measurements on Mantle Peridotite at High Pressure and Temperature

NASA Astrophysics Data System (ADS)

Mistler, G. W.; Ishikawa, M.; Li, B.

2002-12-01

With the success of conducting ultrasonic measurements at high pressure and high temperature in large volume high pressure apparatus with in-situ measurement of the sample length by X-ray imaging, it is now possible to measure elastic wave velocities on aggregate samples with candidate compositions of the mantle to the conditions of the Earth's transition zone in the laboratory. These data can be directly compared with seismic data to distinguish the compositional models in debate. In this work, we carried out velocity measurements on natural peridotite KLB-1 at the conditions of the Earth's upper mantle. Fine powered sample of natural KLB-1 was used as starting material. Specimens for ultrasonic measurements were hot-pressed and equilibrated at various pressure and temperature conditions along geotherm up to the transition zone. The recovered samples were characterized with density measurement, X-ray diffraction and microprobe analysis. Bench top P and S wave velocities of KLB-1 sample sintered at 3-4 GPa and 1400 degree centigrade showed a very good agreement with the VRH average of pyrolite. High pressure and high temperature measurements was conducted up to 7 GPa and 800 degree centigrade using ultrasonic interferometric method in a DIA-type high pressure apparatus in conjunction with X-ray diffraction and X-ray imaging. The utilization of X-ray imaging technique provides direct measurements of sample lengths at high pressure and high temperature, ensuring a precise determination of velocities. The results of P and S wave velocities at high pressure and high temperature as well as their comparison with calculated pyrolite model will be presented.

Identifying Changes in the Probability of High Temperature, High Humidity Heat Wave Events

NASA Astrophysics Data System (ADS)

Ballard, T.; Diffenbaugh, N. S.

2016-12-01

Understanding how heat waves will respond to climate change is critical for adequate planning and adaptation. While temperature is the primary determinant of heat wave severity, humidity has been shown to play a key role in heat wave intensity with direct links to human health and safety. Here we investigate the individual contributions of temperature and specific humidity to extreme heat wave conditions in recent decades. Using global NCEP-DOE Reanalysis II daily data, we identify regional variability in the joint probability distribution of humidity and temperature. We also identify a statistically significant positive trend in humidity over the eastern U.S. during heat wave events, leading to an increased probability of high humidity, high temperature events. The extent to which we can expect this trend to continue under climate change is complicated due to variability between CMIP5 models, in particular among projections of humidity. However, our results support the notion that heat wave dynamics are characterized by more than high temperatures alone, and understanding and quantifying the various components of the heat wave system is crucial for forecasting future impacts.

Converging shock wave focusing and interaction with a target

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nitishinskiy, M.; Efimov, S.; Antonov, O.

2016-04-15

Converging shock waves in liquids can be used efficiently in the research of the extreme state of matter and in various applications. In this paper, the recent results related to the interaction of a shock wave with plasma preliminarily formed in the vicinity of the shock wave convergence are presented. The shock wave is produced by the underwater electrical explosion of a spherical wire array. The plasma is generated prior to the shock wave's arrival by a low-pressure gas discharge inside a quartz capillary placed at the equatorial plane of the array. Analysis of the Stark broadening of H{sub α}more » and H{sub β} spectral lines and line-to-continuum ratio, combined with the ratio of the relative intensities of carbon C III/C II and silicon Si III/Si II lines, were used to determine the plasma density and temperature evolution. It was found that during the first ∼200 ns with respect to the beginning of the plasma compression by the shock wave and when the spectral lines are resolved, the plasma density increases from 2 × 10{sup 17 }cm{sup −3} to 5 × 10{sup 17 }cm{sup −3}, while the temperature remains at the same value of 3–4 eV. Further, following the model of an adiabatically imploding capillary, the plasma density increases >10{sup 19 }cm{sup −3}, leading to the continuum spectra obtained experimentally, and the plasma temperature >30 eV at radii of compression of ≤20 μm. The data obtained indicate that the shock wave generated by the underwater electrical explosion of a spherical wire array retains its uniformity during the main part of its convergence.« less

QBO of temperature in mesopause and lower thermosphere caused by solar activity variations

NASA Astrophysics Data System (ADS)

Shefov, N. N.; Semenov, A. I.

2003-04-01

On the basis of the data of the emission (hydroxyl, sodium and atomic oxygen 557.7 nm) and radiophysical (87-107 km) measurements some regularities of quasi-biennial oscillation (QBO) of the atmospheric temperature at heights of the mesopause and lower thermosphere are investigated. It is shown, that they are closely connected with quasi-biennial variations of solar activity and form within the limits of a cycle of solar activity the fading wave train of oscillations. Such behaviour of the wave train can be adequately described by the Airy function. As a result of the analysis of characteristics of QBO of solar activity during 17-23rd cycles it is shown, that to each 11-years cycle correspond its wave train of QBO. Amplitudes and periods of this wave train decrease during a cycle, i.e. it represents Not harmonious oscillation but it is a cyclic aperiodic oscillation (CAO). Therefore usual methods of Fourier analysis used earlier did not result in the same values of the period. The wave train of the current cycle begins at the end of previous and some time together with the subsequent cycle proceeds. Thus, the time sequence of activity during solar cycle represents superposition of three wave trains. Period of CAO in the beginning of a cycle has ~ 38 months and decreases to the end of a cycle up to ~ 21 months. The first wide negative minimum of Airy function describing of the wave train of CAO corresponds to solar activity minimum in the 11-year cycle. The time scale of the wave train varies from one cycle to another. Full duration of individual wave train is ~ 22 years. Owing to a mutual interference of the consecutive wave trains in the 11-year cycles the observable variations of solar activity are not identical. Structure of CAO obviously displays magnetohydrodynamic processes inside the Sun. This work was supported by the Grant No. 2274 of ISTC.

The correlation between the amplitude of Osborn wave and core body temperature.

PubMed

Omar, Hesham R; Camporesi, Enrico M

2015-08-01

Several reports illustrate an inverse correlation between the Osborn wave (J wave) amplitude and core body temperature. We attempted to study the strength of this correlation. We reviewed all articles reporting hypothermic J waves from 1950-2014 for patient demographics, core body temperature in Celsius (°C), amplitude of the J wave in millimeters (mm), lead with the highest amplitude of J wave, presence of acidosis, PO2, electrolytes and outcome. In cases with more than one electrocardiogram (ECG), the respective core body temperature and J wave amplitude of each ECG were recorded. The main study outcome is to evaluate the correlation between the J wave amplitude and core body temperature in the admission ECG. We have also examined the strength of this relationship in cases with more than one ECG. We attempted to find the most frequent lead that recorded the highest amplitude of the J wave in addition to the correlation between the amplitude of J wave and pH. We found 64 articles comprising a total of 68 cases. When analyzing only cases with more than one reported ECG, there was a strong inverse correlation (r = - 0.682, p<0.001) between J wave amplitude and body temperature: however, when analyzing admission ECG of all cases, the correlation was only moderate (r = - 0.410, p<0.001). The lead with the highest amplitude of the J wave was V4 (44% of the cases, p<0.001) followed by V3 (23.7% of the cases, p<0.001). The amplitude of the J wave in the admission ECG of hypothermic patients may not accurately predict the core body temperature. © The European Society of Cardiology 2014.

Fate of internal waves on a shallow shelf

NASA Astrophysics Data System (ADS)

Davis, Kristen; Arthur, Robert; Reid, Emma; Decarlo, Thomas; Cohen, Anne

2017-11-01

Internal waves strongly influence the physical and chemical environment of coastal ecosystems worldwide. We report novel observations from a distributed temperature sensing (DTS) system that tracked the transformation of internal waves from the shelf break to the surf zone over a shelf-slope region of a coral atoll in the South China Sea. The spatially-continuous view of the near-bottom temperature field provided by the DTS offers a perspective of physical processes previously available only in laboratory settings or numerical models. These processes include internal wave reflection off a natural slope, shoreward transport of dense fluid within trapped cores, internal ``tide pools'' (dense water left behind after the retreat of an internal wave), and internal run-down (near-bottom, offshore-directed jets of water preceding a breaking internal wave). Analysis shows that the fate of internal waves on this shelf - whether they are transmitted into shallow waters or reflected back offshore - is mediated by local water column density and shear structure, with important implications for nearshore distributions of energy, heat, and nutrients. We acknowledge the US Army Research Laboratory DoD Supercomputing Resource Center for computer time on Excalibur, which was used for the numerical simulations in this work. Funding for field work supported by Academia Sinica and for K.D. and E.R. from NSF.

Coastal circulation and sediment dynamics along West Maui, Hawaii; PART IV: measurements of waves, currents, temperature, salinity and turbidity in Honolua Bay, Northwest Maui: 2003-2004

USGS Publications Warehouse

Storlazzi, Curt D.; Presto, M. Kathy

2005-01-01

High-resolution measurements of waves, currents, water levels, temperature, salinity and turbidity were made in Honolua Bay, northwest Maui, Hawaii, during 2003 and 2004 to better understand coastal dynamics in coral reef habitats. Measurements were acquired through two different collection methods. Two hydrographic survey cruises were conducted to acquire spatially-extensive, but temporally-limited, three-dimensional measurements of currents, temperature, salinity and turbidity in the winter and summer of 2003. From mid 2003 through early 2004, a bottom-mounted instrument package was deployed in a water depth of 10 m to collect long-term, single-point high-resolution measurements of waves, currents, water levels, temperature, salinity and turbidity. The purpose of these measurements was to collect hydrographic data to learn how waves, currents and water column properties such as water temperature, salinity and turbidity vary spatially and temporally in a near-shore coral reef system adjacent to a major stream drainage. These measurements support the ongoing process studies being conducted as part of the U.S. Geological Survey (USGS) Coastal and Marine Geology Program's Coral Reef Project; the ultimate goal is to better understand the transport mechanisms of sediment, larvae, pollutants and other particles in coral reef settings. This report, the final part in a series, describes data acquisition, processing and analysis. Previous reports provided data and results on: Long-term measurements of currents, temperature, salinity and turbidity off Kahana (PART I), the spatial structure of currents, temperature, salinity and suspended sediment along West Maui (PART II), and flow and coral larvae and sediment dynamics during the 2003 summer spawning season (PART III).

Numerical Investigation of Crossflow Instability on the HIFiRE-5

NASA Astrophysics Data System (ADS)

Lakebrink, Matthew T.

Stability analysis was performed with the Langley Stability and Transition Analysis Code (LASTRAC) on a 38.1% scale model of the HIFiRE-5 elliptic-cone forebody to study crossflow-induced transition in hypersonic boundary layers. A resolution study consisting of three grids (30e6, 45e6, and 91e6 points) indicated that the fine grid was sufficiently resolved. Results were largely insensitive to grid resolution over the acreage and near the attachment line. The percent variation in second-mode properties along the semi-minor axis was less than 1% between the medium and fine grids. The variation in crossflow-wave properties was less than 0.04% between the medium and fine grids. Comparisons were made between crossflow-wave properties computed using quasi-parallel Linear Stability Theory (LST), the Linear Parabolized Stability Equations (LPSE), and surface marching or two-plane LPSE (2pLPSE). Sensitivity to marching path was also explored by performing analysis along Group-Velocity Lines (GVL) and Inviscid Streamlines (ISL). The wave properties were largely insensitive to analysis type and marching path, with the greatest variation near the attachment line. The LPSE-growth rates were as much as 20% greater than LST. Results from LPSE and 2pLPSE were similar except near the attachment line, where 2pLPSE growth rates were about 30% greater. Growth rates for crossflow and second-mode waves computed with 2pLPSE were compared to Spatial BiGlobal (SBG) analysis. Crossflow growth rates agreed well between 2pLPSE and SBG, indicating that the more expensive SBG approach is unnecessary for crossflow computation over the acreage. Second-mode growth rates along the attachment line had similar peak frequencies between the various methods, but 2pLPSE and LST growth rates were as much as 200% and 30% greater than SBG respectively. These results represent the first comparison between SBG and conventional techniques for crossflow waves, and help to define best practices for the use of each technique. Crossflow-wave computations were compared to measurements made by Dr. Matt Borg in the Boeing AFOSR Mach 6 Quiet Tunnel (BAM6QT). Linear analysis for wave angle, phase speed, peak frequency, and spanwise wavelength agreed well with the experiment for sufficiently low Reynolds numbers. The Reynolds number at which linear theory deviated from the test data was termed the 'linear limit'. A stationary-crossflow N-factor of 8.2 correlated well with the linear limit, as did a traveling-wave amplitude of about 1%. Experimental PSD data was used to identify the onset of turbulence at the downstream end of the model, and the associated stationary-crossflow N-factor based on LST was 9.4. Correlating to the linear limit provides a way to conservatively estimate crossflow-induced transition using LST. Evolution of the crossflow waves between the linear limit and the breakdown to turbulence was studied using Non-linear PSE (NPSE). By exciting a combination of stationary and traveling waves, naturally excited harmonics grew downstream of the linear limit to amplitudes of about 2% based on peak temperature. The wave angles of these harmonics agreed well with the test data. For reasons unknown, such agreement was not realized for phase speed. Initial-amplitude sweeps were performed for both stationary and traveling waves. Initial stationary-wave amplitude had a strong influence on the peak-harmonic amplitude and location of transition onset, while initial amplitude of the traveling-waves primarily influenced the location of transition onset. This is the first dataset from which detailed comparisons have been made between stability analysis and quiet tunnel data for crossflow waves in both the linear and non-linear stages of evolution. Several of these comparisons serve as validation of LASTRAC for crossflow-wave analysis. Finally, to aid the comparison of stability analysis to experimental data in general, the sensitivities of crossflow-wave evolution to small-yaw angles and changes in wall temperature were investigated. A yaw angle of 0.5 degrees resulted in a change in N-factor of about 1 between the same point on opposite halves of the geometry. A 15K increase in wall temperature led to a 0.1 increase in N-factor. These results, which are the first of their kind, highlight the sensitivity of crossflow waves to subtle changes in boundary conditions, and serve to emphasize the importance of high-quality test data for which flow conditions are recorded as precisely as possible.

High Ambient Temperatures and Risk of Motor Vehicle Crashes in Catalonia, Spain (2000–2011): A Time-Series Analysis

PubMed Central

Escalera-Antezana, Juan Pablo; Dadvand, Payam; Llatje, Òscar; Barrera-Gómez, Jose; Cunillera, Jordi; Medina-Ramón, Mercedes; Pérez, Katherine

2015-01-01

Background Experimental studies have shown a decrease in driving performance at high temperatures. The epidemiological evidence for the relationship between heat and motor vehicle crashes is not consistent. Objectives We estimated the impact of high ambient temperatures on the daily number of motor vehicle crashes and, in particular, on crashes involving driver performance factors (namely distractions, driver error, fatigue, or sleepiness). Methods We performed a time-series analysis linking daily counts of motor vehicle crashes and daily temperature or occurrence of heat waves while controlling for temporal trends. All motor vehicle crashes with victims that occurred during the warm period of the years 2000–2011 in Catalonia (Spain) were included. Temperature data were obtained from 66 weather stations covering the region. Poisson regression models adjusted for precipitation, day of the week, month, year, and holiday periods were fitted to quantify the associations. Results The study included 118,489 motor vehicle crashes (an average of 64.1 per day). The estimated risk of crashes significantly increased by 2.9% [95% confidence interval (CI): 0.7%, 5.1%] during heat wave days, and this association was stronger (7.7%, 95% CI: 1.2%, 14.6%) when restricted to crashes with driver performance–associated factors. The estimated risk of crashes with driver performance factors significantly increased by 1.1% (95% CI: 0.1%, 2.1%) for each 1°C increase in maximum temperature. Conclusions Motor vehicle crashes involving driver performance–associated factors were increased in association with heat waves and increasing temperature. These findings are relevant for designing preventive plans in a context of global warming. Citation Basagaña X, Escalera-Antezana JP, Dadvand P, Llatje Ò, Barrera-Gómez J, Cunillera J, Medina-Ramón M, Pérez K. 2015. High ambient temperatures and risk of motor vehicle crashes in Catalonia, Spain (2000–2011): a time-series analysis. Environ Health Perspect 123:1309–1316; http://dx.doi.org/10.1289/ehp.1409223 PMID:26046727

Elastic precursor wave decay in shock-compressed aluminum over a wide range of temperature

NASA Astrophysics Data System (ADS)

Austin, Ryan A.

2018-01-01

The effect of temperature on the dynamic flow behavior of aluminum is considered in the context of precursor wave decay measurements and simulations. In this regard, a dislocation-based model of high-rate metal plasticity is brought into agreement with previous measurements of evolving wave profiles at 300 to 933 K, wherein the amplification of the precursor structure with temperature arises naturally from the dislocation mechanics treatment. The model suggests that the kinetics of inelastic flow and stress relaxation are governed primarily by phonon scattering and radiative damping (sound wave emission from dislocation cores), both of which intensify with temperature. The manifestation of these drag effects is linked to low dislocation density ahead of the precursor wave and the high mobility of dislocations in the face-centered cubic lattice. Simulations performed using other typical models of shock wave plasticity do not reproduce the observed temperature-dependence of elastic/plastic wave structure.

Rayleigh surface acoustic wave as an efficient heating system for biological reactions: investigation of microdroplet temperature uniformity.

PubMed

Roux-Marchand, Thibaut; Beyssen, Denis; Sarry, Frederic; Elmazria, Omar

2015-04-01

When a microdroplet is put on the Rayleigh surface acoustic wave path, longitudinal waves are radiated into the liquid and induce several phenomena such as the wellknown surface acoustic wave streaming. At the same time, the temperature of the microdroplet increases as it has been shown. In this paper, we study the temperature uniformity of a microdroplet heated by Rayleigh surface acoustic wave for discrete microfluidic applications such as biological reactions. To precisely ascertain the temperature uniformity and not interfere with the biological reaction, we used an infrared camera. We then tested the temperature uniformity as a function of three parameters: the microdroplet volume, the Rayleigh surface acoustic wave frequency, and the continuous applied radio frequency power. Based on these results, we propose a new device structure to develop a future lab on a chip based on reaction temperatures.

Tropical waves and the quasi-biennial oscillation in the lower stratosphere

NASA Technical Reports Server (NTRS)

Miller, A. J.; Angell, J. K.; Korshover, J.

1976-01-01

By means of spectrum analysis of 11 years of lower stratospheric daily winds and temperatures at Balboa, Ascension and Canton-Singapore, evidence is presented supporting the existence of two principal wave modes with periods of about 11-17 days (Kelvin waves) and about 4-5 days (mixed Rossby-gravity waves). The structure of the two wave modes, as well as the vertical eddy momentum flux by the waves, is shown to be related to the quasi-biennial cycle, although for the mixed Rossby-gravity waves this is obvious only at Ascension. In addition, the Coriolis term, suggested as a source of vertical easterly momentum flux for the mixed Rossby-gravity waves, is investigated and found to be of the same magnitude as the vertical eddy flux term. Finally, we have examined the mean meridional motion and the meridional eddy momentum flux for its possible association with the quasi- biennial variation.

Wave combustors for trans-atmospheric vehicles

NASA Technical Reports Server (NTRS)

Menees, Gene P.; Adelman, Henry G.; Cambier, Jean-Luc; Bowles, Jeffrey V.

1989-01-01

The Wave Combustor is an airbreathing hypersonic propulsion system which utilizes shock and detonation waves to enhance fuel-air mixing and combustion in supersonic flow. In this concept, an oblique shock wave in the combustor can act as a flameholder by increasing the pressure and temperature of the air-fuel mixture and thereby decreasing the ignition delay. If the oblique shock is sufficiently strong, then the combustion front and the shock wave can couple into a detonation wave. In this case, combustion occurs almost instantaneously in a thin zone behind the wave front. The result is a shorter, lighter engine compared to the scramjet. This engine, which is called the Oblique Detonation Wave Engine (ODWE), can then be utilized to provide a smaller, lighter vehicle or to provide a higher payload capability for a given vehicle weight. An analysis of the performance of a conceptual trans-atmospheric vehicle powered by an ODWE is given here.

Parametric decay of an extraordinary electromagnetic wave in relativistic plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dorofeenko, V. G.; Krasovitskiy, V. B., E-mail: krasovit@mail.ru; Turikov, V. A.

2015-03-15

Parametric instability of an extraordinary electromagnetic wave in plasma preheated to a relativistic temperature is considered. A set of self-similar nonlinear differential equations taking into account the electron “thermal” mass is derived and investigated. Small perturbations of the parameters of the heated plasma are analyzed in the linear approximation by using the dispersion relation determining the phase velocities of the fast and slow extraordinary waves. In contrast to cold plasma, the evanescence zone in the frequency range above the electron upper hybrid frequency vanishes and the asymptotes of both branches converge. Theoretical analysis of the set of nonlinear equations showsmore » that the growth rate of decay instability increases with increasing initial temperature of plasma electrons. This result is qualitatively confirmed by numerical simulations of plasma heating by a laser pulse injected from vacuum.« less

On the mechanism of flow evolution in shock-tube experiments

NASA Astrophysics Data System (ADS)

Kiverin, Alexey; Yakovenko, Ivan

2018-02-01

The paper studies numerically the flow development behind the shock wave propagating inside the tube. The detailed analysis of the flow patterns behind the shock wave allows determination of the gas-dynamical origins of the temperature non-uniformities responsible for the subsequent localized start of chemical reactions in the test mixture. In particular, it is shown that the temperature field structure is determined mainly by the mechanisms of boundary layer instability development. The kinetic energy dissipation related to the flow deceleration inside boundary layer results in local heating of the test gas. At the same time, the heat losses to the tube wall lead to the cooling of the gas. Therefore the temperature stratification takes place on the scales of the boundary layer. As soon as the shock wave reflected from the end-wall of the tube interacts with the developed boundary layer the localized hot regions arise at a certain distance from the end wall. The position of these hot regions is associated with the zones of shock wave interaction with roller vortices at the margin between the boundary layer and the bulk flow. Formulated mechanism of the temperature field evolution can be used to explain the peculiarities of non-steady shock-induced ignition of combustible mixtures with moderate ignition delay times, where the ignition starts inside localized kernels at distance from the end wall.

Semiconductor Quantum Electron Wave Transport, Diffraction, and Interference: Analysis, Device, and Measurement.

NASA Astrophysics Data System (ADS)

Henderson, Gregory Newell

Semiconductor device dimensions are rapidly approaching a fundamental limit where drift-diffusion equations and the depletion approximation are no longer valid. In this regime, quantum effects can dominate device response. To increase further device density and speed, new devices must be designed that use these phenomena to positive advantage. In addition, quantum effects provide opportunities for a new class of devices which can perform functions previously unattainable with "conventional" semiconductor devices. This thesis has described research in the analysis of electron wave effects in semiconductors and the development of methods for the design, fabrication, and characterization of quantum devices based on these effects. First, an exact set of quantitative analogies are presented which allow the use of well understood optical design and analysis tools for the development of electron wave semiconductor devices. Motivated by these analogies, methods are presented for modeling electron wave grating diffraction using both an exact rigorous coupled-wave analysis and approximate analyses which are useful for grating design. Example electron wave grating switch and multiplexer designs are presented. In analogy to thin-film optics, the design and analysis of electron wave Fabry-Perot interference filters are also discussed. An innovative technique has been developed for testing these (and other) electron wave structures using Ballistic Electron Emission Microscopy (BEEM). This technique uses a liquid-helium temperature scanning tunneling microscope (STM) to perform spectroscopy of the electron transmittance as a function of electron energy. Experimental results show that BEEM can resolve even weak quantum effects, such as the reflectivity of a single interface between materials. Finally, methods are discussed for incorporating asymmetric electron wave Fabry-Perot filters into optoelectronic devices. Theoretical and experimental results show that such structures could be the basis for a new type of electrically pumped mid - to far-infrared semiconductor laser.

The structure of ion-acoustic waves in a low-frequency three-component electron-ion space plasma with two-electron populations

NASA Astrophysics Data System (ADS)

Govender, G.; Moolla, S.

2018-07-01

Low-frequency ion-acoustic waves are analysed on the ion time-scale, in a three-component electron-ion space plasma. The solitary waves propagate in the positive x direction relative to an ambient magnetic field ěc {B}_0 which forms static background for a configuration consisting of cool fluid ions and both warm and hot Boltzmann-distributed electrons with temperatures T_{ic}, T_{ew} and T_{eh}, respectively. We derive linear dispersion relation for the waves by introducing first-order density, pressure and velocity perturbations into the ion fluid equations. Additionally, the variation in the nonlinear structure of the waves are investigated by carrying out a full parametric analysis utilising our numerical code. Our results reveal that ion-acoustic waves exhibit well-defined nonlinear spikes at speeds of M≥ 2.25 and an electric field amplitude of E_0=0.85. It is also shown that low wave speeds (M≤ 2), higher densities of the hot electrons, antiparallel drifting of the cool fluid ions, and increased ion temperatures all lead to significant dispersive effects. The ion-acoustic plasma waves featured in this paper have forms that are consistent with those classified as the type-A and type-B broadband electrostatic noise (BEN) observed in the data obtained from earlier satellite missions.

Heat waves over Central Europe in regional climate model simulations

NASA Astrophysics Data System (ADS)

Lhotka, Ondřej; Kyselý, Jan

2014-05-01

Regional climate models (RCMs) have become a powerful tool for exploring impacts of global climate change on a regional scale. The aim of the study is to evaluate the capability of RCMs to reproduce characteristics of major heat waves over Central Europe in their simulations of the recent climate (1961-2000), with a focus on the most severe and longest Central European heat wave that occurred in 1994. We analyzed 7 RCM simulations with a high resolution (0.22°) from the ENSEMBLES project, driven by the ERA-40 reanalysis. In observed data (the E-OBS 9.0 dataset), heat waves were defined on the basis of deviations of daily maximum temperature (Tmax) from the 95% quantile of summer Tmax distribution in grid points over Central Europe. The same methodology was applied in the RCM simulations; we used corresponding 95% quantiles (calculated for each RCM and grid point) in order to remove the bias of modelled Tmax. While climatological characteristics of heat waves are reproduced reasonably well in the RCM ensemble, we found major deficiencies in simulating heat waves in individual years. For example, METNOHIRHAM simulated very severe heat waves in 1996, when no heat wave was observed. Focusing on the major 1994 heat wave, considerable differences in simulated temperature patterns were found among the RCMs. The differences in the temperature patterns were clearly linked to the simulated amount of precipitation during this event. The 1994 heat wave was almost absent in all RCMs that did not capture the observed precipitation deficit, while it was by far most pronounced in KNMI-RACMO that simulated virtually no precipitation over Central Europe during the 15-day period of the heat wave. By contrast to precipitation, values of evaporative fraction in the RCMs were not linked to severity of the simulated 1994 heat wave. This suggests a possible major contribution of other factors such as cloud cover and associated downward shortwave radiation. Therefore, a more detailed analysis of individual components of the energy budget over Central Europe during and before the 1994 heat wave was performed.

Solitary Wave in One-dimensional Buckyball System at Nanoscale

PubMed Central

Xu, Jun; Zheng, Bowen; Liu, Yilun

2016-01-01

We have studied the stress wave propagation in one-dimensional (1-D) nanoscopic buckyball (C60) system by molecular dynamics (MD) simulation and quantitative modeling. Simulation results have shown that solitary waves are generated and propagating in the buckyball system through impacting one buckyball at one end of the buckyball chain. We have found the solitary wave behaviors are closely dependent on the initial temperature and impacting speed of the buckyball chain. There are almost no dispersion and dissipation of the solitary waves (stationary solitary wave) for relatively low temperature and high impacting speed. While for relatively high temperature and low impacting speed the profile of the solitary waves is highly distorted and dissipated after propagating several tens of buckyballs. A phase diagram is proposed to describe the effect of the temperature and impacting speed on the solitary wave behaviors in buckyball system. In order to quantitatively describe the wave behavior in buckyball system, a simple nonlinear-spring model is established, which can describe the MD simulation results at low temperature very well. The results presented in this work may lay a solid step towards the further understanding and manipulation of stress wave propagation and impact energy mitigation at nanoscale. PMID:26891624

Influence of substrate temperatures on the properties of GdF(3) thin films with quarter-wave thickness in the ultraviolet region.

PubMed

Jin, Jingcheng; Jin, Chunshui; Li, Chun; Deng, Wenyuan; Yao, Shun

2015-06-01

High-quality coatings of fluoride materials are in extraordinary demand for use in deep ultraviolet (DUV) lithography. Gadolinium fluoride (GdF₃) thin films were prepared by a thermal boat evaporation process at different substrate temperatures. GdF₃ thin film was set at quarter-wave thickness (∼27  nm) with regard to their common use in DUV/vacuum ultraviolet optical stacks; these thin films may significantly differ in nanostructural properties at corresponding depositing temperatures, which would crucially influence the performance of the multilayers. The measurement and analysis of optical, structural, and mechanical properties of GdF₃ thin films have been performed in a comprehensive characterization cycle. It was found that depositing GdF₃ thin films at relative higher temperature would form a rather dense, smooth, homogeneous structure within this film thickness scale.

Ultrasonic and metallographic studies on AISI 4140 steel exposed to hydrogen at high pressure and temperature

NASA Astrophysics Data System (ADS)

Oruganti, Malavika

This thesis conducts an investigation to study the effects of hydrogen exposure at high temperature and pressure on the behavior of AISI 4140 steel. Piezoelectric ultrasonic technique was primarily used to evaluate surface longitudinal wave velocity and defect geometry variations, as related to time after exposure to hydrogen at high temperature and pressure. Critically refracted longitudinal wave technique was used for the former and pulse-echo technique for the latter. Optical microscopy and scanning electron microscopy were used to correlate the ultrasonic results with the microstructure of the steel and to provide better insight into the steel behavior. The results of the investigation indicate that frequency analysis of the defect echo, determined using the pulse-echo technique at regular intervals of time, appears to be a promising tool for monitoring defect growth induced by a high temperature and high pressure hydrogen-related attack.

Surface wave effects on water temperature in the Baltic Sea: simulations with the coupled NEMO-WAM model

NASA Astrophysics Data System (ADS)

Alari, Victor; Staneva, Joanna; Breivik, Øyvind; Bidlot, Jean-Raymond; Mogensen, Kristian; Janssen, Peter

2016-08-01

Coupled circulation (NEMO) and wave model (WAM) system was used to study the effects of surface ocean waves on water temperature distribution and heat exchange at regional scale (the Baltic Sea). Four scenarios—including Stokes-Coriolis force, sea-state dependent energy flux (additional turbulent kinetic energy due to breaking waves), sea-state dependent momentum flux and the combination these forcings—were simulated to test the impact of different terms on simulated temperature distribution. The scenario simulations were compared to a control simulation, which included a constant wave-breaking coefficient, but otherwise was without any wave effects. The results indicate a pronounced effect of waves on surface temperature, on the distribution of vertical temperature and on upwelling's. Overall, when all three wave effects were accounted for, did the estimates of temperature improve compared to control simulation. During the summer, the wave-induced water temperature changes were up to 1 °C. In northern parts of the Baltic Sea, a warming of the surface layer occurs in the wave included simulations in summer months. This in turn reduces the cold bias between simulated and measured data, e.g. the control simulation was too cold compared to measurements. The warming is related to sea-state dependent energy flux. This implies that a spatio-temporally varying wave-breaking coefficient is necessary, because it depends on actual sea state. Wave-induced cooling is mostly observed in near-coastal areas and is the result of intensified upwelling in the scenario, when Stokes-Coriolis forcing is accounted for. Accounting for sea-state dependent momentum flux results in modified heat exchange at the water-air boundary which consequently leads to warming of surface water compared to control simulation.

Analysis of heat wave occurrences in the Carpathian basin using regional climate model simulations

NASA Astrophysics Data System (ADS)

Bartha, E. B.; Pongracz, R.; Bartholy, J.

2012-04-01

Human health is very likely affected by regional consequences of global warming. One of the most severe impacts is probably associated to temperature-related climatological extremes, such as heat waves. In the coming decades hot conditions in most regions of the world are very likely to occur more frequently and more intensely than in the recent decades. In order to develop adaptation and mitigation strategies on local scale, it is essential to analyze the projected changes related to warming climatic conditions including heat waves. In 2004, a Heat Health Watch Warning System was developed in Hungary on the basis of a retrospective analysis of mortality and meteorological data to anticipate heat waves that may result in a large excess of mortality. In the frame of this recently introduced Health Watch System, three levels of heat wave warning are applied. They are associated to the daily mean temperature values, and defined as follows: - Warning level 1 (advisory for internal use) is issued when the daily mean temperature exceeds 25 °C. - Warning level 2 (heat wave watch) is issued when the daily mean temperature for at least 3 consecutive days exceeds 25 °C. - Warning level 3 (heat wave alert) is issued when the daily mean temperature for at least 3 consecutive days exceeds 27 °C. In the present study, frequency of the above climatic conditions are analyzed using regional climate model (RCM) experiments are analyzed for the recent past and the coming decades (1961-2100) for the Carpathian basin. At the Dept. of Meteorology, Eotvos Lorand University two different RCMs have been adapted: RegCM (with 10 km horizontal resolution, originally developed by Giorgi et al., currently, available from the International Centre for Theoretical Physics, ICTP) and PRECIS (with 25 km horizontal resolution, developed at the UK Met Office, Hadley Centre). Their initial and lateral boundary conditions have been provided by global climate models ECHAM and HadCM3, respectively. For both RCMs A1B emission scenario was used. The climatic conditions of 1961-1990 (as a reference), and 2021-2050, 2071-2100 future periods are evaluated using bias corrected daily mean temperature outputs of both RegCM and PRECIS. Based on the results the following main conclusions can be drawn: (i) Heat waves are very likely to occur more frequently in the 21st century than in the reference period, 1961-1990. (ii) By the end of the 21st century heat warning level 3 is projected to occur with similar frequency as the heat warning level 1 in the reference period. (iii) By the end of the 21st century the average first occurrence of the heat warning days is simulated to shift earlier, and the average last occurrence later, than in the reference period - thus the length of the heat wave season is projected to become remarkably larger. (iv) For each time slices (both reference and future periods), PRECIS simulations suggest a more often occurrence of heat warning cases in the Carpathian basin than the RegCM experiments.

A general numerical model for wave rotor analysis

NASA Technical Reports Server (NTRS)

Paxson, Daniel W.

1992-01-01

Wave rotors represent one of the promising technologies for achieving very high core temperatures and pressures in future gas turbine engines. Their operation depends upon unsteady gas dynamics and as such, their analysis is quite difficult. This report describes a numerical model which has been developed to perform such an analysis. Following a brief introduction, a summary of the wave rotor concept is given. The governing equations are then presented, along with a summary of the assumptions used to obtain them. Next, the numerical integration technique is described. This is an explicit finite volume technique based on the method of Roe. The discussion then focuses on the implementation of appropriate boundary conditions. Following this, some results are presented which first compare the numerical approximation to the governing differential equations and then compare the overall model to an actual wave rotor experiment. Finally, some concluding remarks are presented concerning the limitations of the simplifying assumptions and areas where the model may be improved.

Viscous Analysis of Pulsating Hydrodynamic Instability and Thermal Coupling Liquid-Propellant Combustion

NASA Technical Reports Server (NTRS)

Margolis, Stephen B.; Sacksteder, Kurt (Technical Monitor)

2000-01-01

A pulsating form of hydrodynamic instability has recently been shown to arise during liquid-propellant deflagration in those parameter regimes where the pressure-dependent burning rate is characterized by a negative pressure sensitivity. This type of instability can coexist with the classical cellular, or Landau form of hydrodynamic instability, with the occurrence of either dependent on whether the pressure sensitivity is sufficiently large or small in magnitude. For the inviscid problem, it has been shown that, when the burning rate is realistically allowed to depend on temperature as well as pressure, sufficiently large values of the temperature sensitivity relative to the pressure sensitivity causes like pulsating form of hydrodynamic instability to become dominant. In that regime, steady, planar burning becomes intrinsically unstable to pulsating disturbances whose wave numbers are sufficiently small. This analysis is extended to the fully viscous case, where it is shown that although viscosity is stabilizing for intermediate and larger wave number perturbations, the intrinsic pulsating instability for small wave numbers remains. Under these conditions, liquid-propellant combustion is predicted to be characterized by large unsteady cells along the liquid/gas interface.

A Simple and Accurate Analysis of Conductivity Loss in Millimeter-Wave Helical Slow-Wave Structures

NASA Astrophysics Data System (ADS)

Datta, S. K.; Kumar, Lalit; Basu, B. N.

2009-04-01

Electromagnetic field analysis of a helix slow-wave structure was carried out and a closed form expression was derived for the inductance per unit length of the transmission-line equivalent circuit of the structure, taking into account the actual helix tape dimensions and surface current on the helix over the actual metallic area of the tape. The expression of the inductance per unit length, thus obtained, was used for estimating the increment in the inductance per unit length caused due to penetration of the magnetic flux into the conducting surfaces following Wheeler’s incremental inductance rule, which was subsequently interpreted for the attenuation constant of the propagating structure. The analysis was computationally simple and accurate, and accrues the accuracy of 3D electromagnetic analysis by allowing the use of dispersion characteristics obtainable from any standard electromagnetic modeling. The approach was benchmarked against measurement for two practical structures, and excellent agreement was observed. The analysis was subsequently applied to demonstrate the effects of conductivity on the attenuation constant of a typical broadband millimeter-wave helical slow-wave structure with respect to helix materials and copper plating on the helix, surface finish of the helix, dielectric loading effect and effect of high temperature operation - a comparative study of various such aspects are covered.

The interannual variation in monthly temperature over Northeast China during summer

NASA Astrophysics Data System (ADS)

Chen, Wei; Lu, Riyu

2014-05-01

The interannual variations of summer surface air temperature over Northeast China (NEC) were investigated through a month-to-month analysis from May to August. The results suggested that the warmer temperature over NEC is related to a local positive 500-hPa geopotential height anomaly for all four months. However, the teleconnection patterns of atmospheric circulation anomalies associated with the monthly surface air temperature over NEC behave as a distinguished subseasonal variation, although the local positive height anomaly is common from month to month. In May and June, the teleconnection pattern is characterized by a wave train in the upper and middle troposphere from the Indian Peninsula to NEC. This wave train is stronger in June than in May, possibly due to the positive feedback between the wave train and the South Asian rainfall anomaly in June, when the South Asian summer monsoon has been established. In July and August, however, the teleconnection pattern associated with the NEC temperature anomalies is characterized by an East Asia/Pacific (EAP) or Pacific/Japan (PJ) pattern, with the existence of precipitation anomalies over the Philippine Sea and the South China Sea. This pattern is much clearer in July corresponding to the stronger convection over the Philippine Sea compared to that in August.

Numerical Analysis on Non-Equilibrium Mechanism of Laser-Supported Detonation Wave Using Multiply-Charged Ionization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shiraishi, Hiroyuki

Laser-Supported Detonation (LSD), one type of Laser-Supported Plasma (LSP), is considered as the most important phenomena because it can generate high pressure and high temperature for laser absorption. In this study, I have numerically simulated the 1-D LSD waves propagating through a helium gas, in which Multiply-charged ionization model is considered for describing an accurate ionization process.

REMOTE SENSING IN OCEANOGRAPHY.

DTIC Science & Technology

remote sensing from satellites. Sensing of oceanographic variables from aircraft began with the photographing of waves and ice. Since then remote measurement of sea surface temperatures and wave heights have become routine. Sensors tested for oceanographic applications include multi-band color cameras, radar scatterometers, infrared spectrometers and scanners, passive microwave radiometers, and radar imagers. Remote sensing has found its greatest application in providing rapid coverage of large oceanographic areas for synoptic and analysis and

Response of water temperature to surface wave effects in the Baltic Sea: simulations with the coupled NEMO-WAM model

NASA Astrophysics Data System (ADS)

Alari, Victor; Staneva, Joanna; Breivik, Øyvind; Bidlot, Jean-Raymond; Mogensen, Kristian; Janssen, Peter

2016-04-01

The effects of wind waves on the Baltic Sea water temperature has been studied by coupling the hydrodynamical model NEMO with the wave model WAM. The wave forcing terms that have been taken into consideration are: Stokes-Coriolis force, seastate dependent energy flux and sea-state dependent momentum flux. The combined role of these processes as well as their individual contributions on simulated temperature is analysed. The results indicate a pronounced effect of waves on surface temperature, on the distribution of vertical temperature and on upwellinǵs. In northern parts of the Baltic Sea a warming of the surface layer occurs in the wave included simulations. This in turn reduces the cold bias between simulated and measured data. The warming is primarily caused by sea-state dependent energy flux. Wave induced cooling is mostly observed in near coastal areas and is mainly due to Stokes-Coriolis forcing. The latter triggers effect of intensifying upwellings near the coasts, depending on the direction of the wind. The effect of sea-state dependent momentum flux is predominantly to warm the surface layer. During the summer the wave induced water temperature changes were up to 1 °C.

Propagation characteristics of ultrasonic guided waves in continuously welded rail

NASA Astrophysics Data System (ADS)

Yao, Wenqing; Sheng, Fuwei; Wei, Xiaoyuan; Zhang, Lei; Yang, Yuan

2017-07-01

Rail defects cause numerous railway accidents. Trains are derailed and serious consequences often occur. Compared to traditional bulk wave testing, ultrasonic guided waves (UGWs) can provide larger monitoring ranges and complete coverage of the waveguide cross-section. These advantages are of significant importance for the non-destructive testing (NDT) of the continuously welded rail, and the technique is therefore widely used in high-speed railways. UGWs in continuous welded rail (CWR) and their propagation characteristics have been discussed in this paper. Finite element methods (FEMs) were used to accomplish a vibration modal analysis, which is extended by a subsequent dispersion analysis. Wave structure features were illustrated by displacement profiles. It was concluded that guided waves have the ability to detect defects in the rail via choice of proper mode and frequency. Additionally, thermal conduction that is caused by temperature variation in the rail is added into modeling and simulation. The results indicated that unbalanced thermal distribution may lead to the attenuation of UGWs in the rail.

Analysis of localized fringes in the holographic optical Schlieren system

NASA Technical Reports Server (NTRS)

Kurtz, R. L.

1980-01-01

The relation between localization of interference fringes in classical and holographic interferometry is reviewed and an application of holographic interferometry is considered for which the object is a transparent medium with nonhomogeneous refractive index. The technique is based on the analysis of the optical path length change of the object wave as it propagates through a transparent medium. Phase shifts due to variations of the speed of light within the medium give rise to an interference pattern. The resulting interferogram can be used to determine the physical properties of the medium or transparent object. Such properties include the mass density of fluids, electron densities of plasmas, the temperature of fluids, the chemical species concentration of fluids, and the state of stress in solids. The optical wave used can be either a simple plane or spherical wave, or it may be a complicated spatial wave scattered by a diffusing screen. The mathematical theory on the formation and analysis of localized fringes, the general theoretical concepts used, and a computer code for analysis are included along with the inversion of fringe order data.

Incommensurate Phonon Anomaly and the Nature of Charge Density Waves in Cuprates

DOE PAGES

Miao, H.; Ishikawa, D.; Heid, R.; ...

2018-01-18

While charge density wave (CDW) instabilities are ubiquitous to superconducting cuprates, the different ordering wave vectors in various cuprate families have hampered a unified description of the CDW formation mechanism. Here, we investigate the temperature dependence of the low-energy phonons in the canonical CDW-ordered cuprate La 1.875Ba 0.125CuO 4. We discover that the phonon softening wave vector associated with CDW correlations becomes temperature dependent in the high-temperature precursor phase and changes from a wave vector of 0.238 reciprocal lattice units (r.l.u.) below the ordering transition temperature to 0.3 r.l.u. at 300 K. This high-temperature behavior also shows that “214”-type cupratesmore » can host CDW correlations at a similar wave vector to previously reported CDW correlations in non-214-type cuprates such as YBa 2Cu 3O 6+δ. This indicates that cuprate CDWs may arise from the same underlying instability despite their apparently different low-temperature ordering wave vectors.« less

Incommensurate Phonon Anomaly and the Nature of Charge Density Waves in Cuprates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miao, H.; Ishikawa, D.; Heid, R.

While charge density wave (CDW) instabilities are ubiquitous to superconducting cuprates, the different ordering wave vectors in various cuprate families have hampered a unified description of the CDW formation mechanism. Here, we investigate the temperature dependence of the low-energy phonons in the canonical CDW-ordered cuprate La 1.875Ba 0.125CuO 4. We discover that the phonon softening wave vector associated with CDW correlations becomes temperature dependent in the high-temperature precursor phase and changes from a wave vector of 0.238 reciprocal lattice units (r.l.u.) below the ordering transition temperature to 0.3 r.l.u. at 300 K. This high-temperature behavior also shows that “214”-type cupratesmore » can host CDW correlations at a similar wave vector to previously reported CDW correlations in non-214-type cuprates such as YBa 2Cu 3O 6+δ. This indicates that cuprate CDWs may arise from the same underlying instability despite their apparently different low-temperature ordering wave vectors.« less

Seasonal variation of upper mesospheric temperatures from the OH and O2 nightglow over King Sejong Station, Antarctica

NASA Astrophysics Data System (ADS)

Kim, J.-H.; Kim, Y. H.; Moon, B.-K.; Chung, J.-K.; Won, Y.-I.

A spectral airglow temperature imager SATI was operated at King Sejong Station 62 22 r S 301 2 r E Korea Antarctic Research Station during a period of 2002 - 2005 Rotational temperatures from the OH 6-2 and O 2 0-1 band airglow were obtained for more than 600 nights during the 4 year operation Both the OH and O 2 temperatures show similar seasonal variations which change significantly year by year A maximum temperature occurred early May in 2003 and 2004 whereas two maxima appeared in April and August in 2002 The 2005 data show only a broad and weak maximum during months of April and May The data also show oscillations with periods of hours that seem to relate to tides and gravity waves and fluctuations with timescales of days that could be due to planetary waves Detailed analysis will be performed to the data set to identify major atmospheric oscillations or variation over hours days and seasons

An analysis of heat wave trends using heat index in East Malaysia

NASA Astrophysics Data System (ADS)

Suparta, W.; Yatim, A. N. M.

2017-05-01

This paper aimed to investigate the heat wave trends in East Malaysia based on the National Weather Services (NWS) Heat Index. The heat index was calculated by using mean temperature and mean relative humidity on monthly basis for 5 meteorological stations in East Malaysia during the period 2008 to 2010. The trends for heat wave were estimated from Heat Index based on the least square regression analysis at each station level. Results showed that the heat wave trends are increasing at all stations. The highest heat index was occurred in Sandakan on July 2010 with heat index 35°C while the lowest heat index happened at Kuching in January 2009 with 27.3°C. From the heat wave observed, East Malaysia is still in caution categories or normal condition (27°C-32°C) and the extreme caution (32°C-41°C) was observed during southwest monsoon (May-July). The safety condition of heat waves in East Malaysia is possibly due to weak to moderate El Nino occurred during the period of observation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sano, Yukio; Abe, Akihisa; Tokushima, Koji

The aim of this study is to examine the difference between shock temperatures predicted by an equation for temperature inside a steady wave front and the Walsh-Christian equation. Calculations are for yttria-doped tetragonal zirconia, which shows an elastic-plastic and a phase transition: Thus the shock waves treated are multiple structure waves composed of one to three steady wave fronts. The evaluated temperature was 3350K at the minimum specific volume of 0.1175 cm{sup 3}/g (or maximum Hugoniot shock pressure of 140GPa) considered in the present examination, while the temperature predicted by the Walsh-Christian equation under identical conditions was 2657K. The causemore » of the large temperature discrepancy is considered to be that the present model treats nonequilibrium states inside steady waves.« less

Electromagnetic drift waves dispersion for arbitrarily collisional plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Wonjae, E-mail: wol023@ucsd.edu; Krasheninnikov, Sergei I., E-mail: skrash@mae.ucsd.edu; Angus, J. R.

2015-07-15

The impacts of the electromagnetic effects on resistive and collisionless drift waves are studied. A local linear analysis on an electromagnetic drift-kinetic equation with Bhatnagar-Gross-Krook-like collision operator demonstrates that the model is valid for describing linear growth rates of drift wave instabilities in a wide range of plasma parameters showing convergence to reference models for limiting cases. The wave-particle interactions drive collisionless drift-Alfvén wave instability in low collisionality and high beta plasma regime. The Landau resonance effects not only excite collisionless drift wave modes but also suppress high frequency electron inertia modes observed from an electromagnetic fluid model in collisionlessmore » and low beta regime. Considering ion temperature effects, it is found that the impact of finite Larmor radius effects significantly reduces the growth rate of the drift-Alfvén wave instability with synergistic effects of high beta stabilization and Landau resonance.« less

Residual Circulation and Temperature Changes during the Evolution of Stratospheric Sudden Warmings Revealed in MERRA

NASA Astrophysics Data System (ADS)

Song, Byeong-Gwon; Chun, Hye-Yeong; Kim, Young-Ha

2015-04-01

A composite analysis for 21 stratospheric sudden warming (SSW) cases in 1979-2012 northern winter is performed using the MERRA reanalysis in order to investigate the changes in residual circulation and temperature during the SSW evolution. The SSW cases are classified as Type-1 and Type-2, based on the relative amplitude of planetary waves with zonal wavenumbers 1 and 2. The residual circulation induced by each forcing term in the transformed Eulerian mean (TEM) equation and the temperature advection associated with the circulation are calculated for both types of SSW. It is found that strong poleward and downward motion exists in the polar stratosphere just before the central date of SSW, which is induced primarily by the Eliassen-Palm flux divergence forcing (EPD). Gravity-wave drag (GWD) induces strong poleward and downward motion in the lower mesosphere. The temperature advection is significantly increased in the stratosphere before the central date of the SSW, as a result of the strong downward motion due to the EPD. However, the temperature change in the lower mesosphere is small despite the strong downward motion, because the vertical gradient of the potential temperature is relatively small at these altitudes. The temperature change in the stratosphere before the SSW is more rapid for Type-2 than Type-1. After the central date of SSW, the polar stratospheric temperature is recovered primarily by diabatic heating rather than by the residual circulation associated with wave forcing. Difference in the speed of temperature recovery between the two types of SSW is not significant.

Gravitational Wave Experiments - Proceedings of the First Edoardo Amaldi Conference

NASA Astrophysics Data System (ADS)

Coccia, E.; Pizzella, G.; Ronga, F.

1995-07-01

The Table of Contents for the full book PDF is as follows: * Foreword * Notes on Edoardo Amaldi's Life and Activity * PART I. INVITED LECTURES * Sources and Telescopes * Sources of Gravitational Radiation for Detectors of the 21st Century * Neutrino Telescopes * γ-Ray Bursts * Space Detectors * LISA — Laser Interferometer Space Antenna for Gravitational Wave Measurements * Search for Massive Coalescing Binaries with the Spacecraft ULYSSES * Interferometers * The LIGO Project: Progress and Prospects * The VIRGO Experiment: Status of the Art * GEO 600 — A 600-m Laser Interferometric Gravitational Wave Antenna * 300-m Laser Interferometer Gravitational Wave Detector (TAMA300) in Japan * Resonant Detectors * Search for Continuous Gravitational Wave from Pulsars with Resonant Detector * Operation of the ALLEGRO Detector at LSU * Preliminary Results of the New Run of Measurements with the Resonant Antenna EXPLORER * Operation of the Perth Cryogenic Resonant-Bar Gravitational Wave Detector * The NAUTILUS Experiment * Status of the AURIGA Gravitational Wave Antenna and Perspectives for the Gravitational Waves Search with Ultracryogenic Resonant Detectors * Ultralow Temperature Resonant-Mass Gravitational Radiation Detectors: Current Status of the Stanford Program * Electromechanical Transducers and Bandwidth of Resonant-Mass Gravitational-Wave Detectors * Fully Numerical Data Analysis for Resonant Gravitational Wave Detectors: Optimal Filter and Available Information * PART II. CONTRIBUTED PAPERS * Sources and Telescopes * The Local Supernova Production * Periodic Gravitational Signals from Galactic Pulsars * On a Possibility of Scalar Gravitational Wave Detection from the Binary Pulsars PSR 1913+16 * Kazan Gravitational Wave Detector “Dulkyn”: General Concept and Prospects of Construction * Hierarchical Approach to the Theory of Detection of Periodic Gravitational Radiation * Application of Gravitational Antennae for Fundamental Geophysical Problems * On Production of Gravitational Radiation by Particle Accelerators and by High Power Lasers * NESTOR: An Underwater Cerenkov Detector for Neutrino Astronomy * A Cosmic-Ray Veto System for the Gravitational Wave Detector NAUTLUS * Interferometers * Development of a 20m Prototype Laser Interferometric Gravitational Wave Detector at NAO * Production of Higher-Order Light Modes by High Quality Optical Components * Vibration Isolation and Suspension Systems for Laser Interferometer Gravitational Wave Detectors * Quality Factors of Stainless Steel Pendulum Wires * Reduction of Suspension Thermal Noises in Laser Free Masses Gravitational Antenna by Correlation of the Output with Additional Optical Signal * Resonant Detectors * Regeneration Effects in a Resonant Gravitational Wave Detector * A Cryogenic Sapphire Transducer with Double Frequency Pumping for Resonant Mass GW Detectors * Effect of Parametric Instability of Gravitational Wave Antenna with Microwave Cavity Transducer * Resonators of Novel Geometry for Large Mass Resonant Transducers * Measurements on the Gravitational Wave Antenna ALTAIR Equipped with a BAE Transducer * The Rome BAE Transducer: Perspectives of its Application to Ultracryogenic Gravitational Wave Antennas * Behavior of a de SQUID Tightly Coupled to a High-Q Resonant Transducer * High Q-Factor LC Resonators for Optimal Coupling * Comparison Between Different Data Analysis Procedures for Gravitational Wave Pulse Detection * Supernova 1987A Rome Maryland Gravitational Radiation Antenna Observations * Analysis of the Data Recorded by the Maryland and Rome Gravitational-Wave Detectors and the Seismic Data from Moscow and Obninsk Station during SN1987A * Multitransducer Resonant Gravitational Antennas * Local Array of High Frequency Antennas * Interaction Cross-Sections for Spherical Resonant GW Antennae * Signal-To-Noise Analysis for a Spherical Gravitational Wave Antenna Instrumented with Multiple Transducers * On the Design of Ultralow Temperature Spherical Gravitational Wave Detectors * List of Participants

Wave Forcing of Saturn's Equatorial Oscillation

NASA Technical Reports Server (NTRS)

Flasar, F. M.; Schlinder, P. J.; Guerlet, S.; Fouchet, T.

2011-01-01

Ground-based measurements and Cassini data from CIRS thermal-infrared spectra and radio-occultation soundings have characterized the spatial structure and temporal behavior of a 15-year equatorial oscillation in Saturn's stratosphere. The equatorial region displays a vertical pattern of alternating warm and cold anomalies and, concomitantly, easterly and westerly winds relative to the cloud-top winds, with a peak-to-peak amplitude of 200 m/s. Comparison of the Cassini data over a four-year period has established that the pattern of mean zonal winds and temperatures descends at a rate of roughly I scale height over 4 years. This behavior is reminiscent of the equatorial oscillations in Earth's middle atmosphere. Here the zonal-mean spatial structure and descending pattern are driven by the absorption of vertically propagating waves. The maximum excursions in the pattern of easterly and westerly winds is determined by the limits of the zonal phase velocities of the waves. Here we report on the characterization of the waves seen in the temperature profiles retrieved from the Cassini radio-occultation soundings. The equatorial profiles exhibit a complex pattern of wavelike structure with dimensions one pressure scale height and smaller. We combine a spectral decomposition with a WKBJ analysis, where the vertical wavelength is assumed to vary slowly with the ambient static stability and doppler-shifted phase velocity of the wave. Use of the temperature and zonal wind maps from CIRS makes this approach viable. On Earth, the wave forcing associated with the equatorial oscillations generates secondary meridional circulations that affect the mean flow and planetary wave ducting well away from the equator. This may relate to the triggering of the recently reported mid-latitude storms on Saturn.

Spatial gravity wave characteristics obtained from multiple OH(3-1) airglow temperature time series

NASA Astrophysics Data System (ADS)

Wachter, Paul; Schmidt, Carsten; Wüst, Sabine; Bittner, Michael

2015-12-01

We present a new approach for the detection of gravity waves in OH-airglow observations at the measurement site Oberpfaffenhofen (11.27°E, 48.08°N), Germany. The measurements were performed at the German Remote Sensing Data Center (DFD) of the German Aerospace Center (DLR) during the period from February 4th, 2011 to July 6th, 2011. In this case study the observations were carried out by three identical Ground-based Infrared P-branch Spectrometers (GRIPS). These instruments provide OH(3-1) rotational temperature time series, which enable spatio-temporal investigations of gravity wave characteristics in the mesopause region. The instruments were aligned in such a way that their fields of view (FOV) formed an equilateral triangle in the OH-emission layer at a height of 87 km. The Harmonic Analysis is applied in order to identify joint temperature oscillations in the three individual datasets. Dependent on the specific gravity wave activity in a single night, it is possible to detect up to four different wave patterns with this method. The values obtained for the waves' periods and phases are then used to derive further parameters, such as horizontal wavelength, phase velocity and the direction of propagation. We identify systematic relationships between periods and amplitudes as well as between periods and horizontal wavelengths. A predominant propagation direction towards the East and North-North-East characterizes the waves during the observation period. There are also indications of seasonal effects in the temporal development of the horizontal wavelength and the phase velocity. During late winter and early spring the derived horizontal wavelengths and the phase velocities are smaller than in the subsequent period from early April to July 2011.

Performance Benefits for Wave Rotor-Topped Gas Turbine Engines

NASA Technical Reports Server (NTRS)

Jones, Scott M.; Welch, Gerard E.

1996-01-01

The benefits of wave rotor-topping in turboshaft engines, subsonic high-bypass turbofan engines, auxiliary power units, and ground power units are evaluated. The thermodynamic cycle performance is modeled using a one-dimensional steady-state code; wave rotor performance is modeled using one-dimensional design/analysis codes. Design and off-design engine performance is calculated for baseline engines and wave rotor-topped engines, where the wave rotor acts as a high pressure spool. The wave rotor-enhanced engines are shown to have benefits in specific power and specific fuel flow over the baseline engines without increasing turbine inlet temperature. The off-design steady-state behavior of a wave rotor-topped engine is shown to be similar to a conventional engine. Mission studies are performed to quantify aircraft performance benefits for various wave rotor cycle and weight parameters. Gas turbine engine cycles most likely to benefit from wave rotor-topping are identified. Issues of practical integration and the corresponding technical challenges with various engine types are discussed.

Sensitivity of idealised baroclinic waves to mean atmospheric temperature and meridional temperature gradient changes

NASA Astrophysics Data System (ADS)

Rantanen, Mika; Räisänen, Jouni; Sinclair, Victoria A.; Järvinen, Heikki

2018-06-01

The sensitivity of idealised baroclinic waves to different atmospheric temperature changes is studied. The temperature changes are based on those which are expected to occur in the Northern Hemisphere with climate change: (1) uniform temperature increase, (2) decrease of the lower level meridional temperature gradient, and (3) increase of the upper level temperature gradient. Three sets of experiments are performed, first without atmospheric moisture, thus seeking to identify the underlying adiabatic mechanisms which drive the response of extra-tropical storms to changes in the environmental temperature. Then, similar experiments are performed in a more realistic, moist environment, using fixed initial relative humidity distribution. Warming the atmosphere uniformly tends to decrease the kinetic energy of the cyclone, which is linked both to a weaker capability of the storm to exploit the available potential energy of the zonal mean flow, and less efficient production of eddy kinetic energy in the wave. Unsurprisingly, the decrease of the lower level temperature gradient weakens the resulting cyclone regardless of the presence of moisture. The increase of the temperature gradient in the upper troposphere has a more complicated influence on the storm dynamics: in the dry atmosphere the maximum eddy kinetic energy decreases, whereas in the moist case it increases. Our analysis suggests that the slightly unexpected decrease of eddy kinetic energy in the dry case with an increased upper tropospheric temperature gradient originates from the weakening of the meridional heat flux by the eddy. However, in the more realistic moist case, the diabatic heating enhances the interaction between upper- and low-level potential vorticity anomalies and hence helps the surface cyclone to exploit the increased upper level baroclinicity.

Radiative effects of ozone waves on the Northern Hemisphere polar vortex and its modulation by the QBO

NASA Astrophysics Data System (ADS)

Silverman, Vered; Harnik, Nili; Matthes, Katja; Lubis, Sandro W.; Wahl, Sebastian

2018-05-01

The radiative effects induced by the zonally asymmetric part of the ozone field have been shown to significantly change the temperature of the NH winter polar cap, and correspondingly the strength of the polar vortex. In this paper, we aim to understand the physical processes behind these effects using the National Center for Atmospheric Research (NCAR)'s Whole Atmosphere Community Climate Model, run with 1960s ozone-depleting substances and greenhouse gases. We find a mid-winter polar vortex influence only when considering the quasi-biennial oscillation (QBO) phases separately, since ozone waves affect the vortex in an opposite manner. Specifically, the emergence of a midlatitude QBO signal is delayed by 1-2 months when radiative ozone-wave effects are removed. The influence of ozone waves on the winter polar vortex, via their modulation of shortwave heating, is not obvious, given that shortwave heating is largest during fall, when planetary stratospheric waves are weakest. Using a novel diagnostic of wave 1 temperature amplitude tendencies and a synoptic analysis of upward planetary wave pulses, we are able to show the chain of events that lead from a direct radiative effect on weak early fall upward-propagating planetary waves to a winter polar vortex modulation. We show that an important stage of this amplification is the modulation of individual wave life cycles, which accumulate during fall and early winter, before being amplified by wave-mean flow feedbacks. We find that the evolution of these early winter upward planetary wave pulses and their induced stratospheric zonal mean flow deceleration is qualitatively different between QBO phases, providing a new mechanistic view of the extratropical QBO signal. We further show how these differences result in opposite radiative ozone-wave effects between east and west QBOs.

Magnetospheric Whistler Mode Raytracing with the Inclusion of Finite Electron and ion Temperature

NASA Astrophysics Data System (ADS)

Maxworth, Ashanthi S.

Whistler mode waves are a type of a low frequency (100 Hz - 30 kHz) wave, which exists only in a magnetized plasma. These waves play a major role in Earth's magnetosphere. Due to the impact of whistler mode waves in many fields such as space weather, satellite communications and lifetime of space electronics, it is important to accurately predict the propagation path of these waves. The method used to determine the propagation path of whistler waves is called numerical raytracing. Numerical raytracing determines the power flow path of the whistler mode waves by solving a set of equations known as the Haselgrove's equations. In the majority of the previous work, raytracing was implemented assuming a cold background plasma (0 K), but the actual magnetosphere is at a temperature of about 1 eV (11600 K). In this work we have modified the numerical raytracing algorithm to work at finite electron and ion temperatures. The finite temperature effects have also been introduced into the formulations for linear cyclotron resonance wave growth and Landau damping, which are the primary mechanisms for whistler mode growth and attenuation in the magnetosphere. Including temperature increases the complexity of numerical raytracing, but the overall effects are mostly limited to increasing the group velocity of the waves at highly oblique wave normal angles.

Trend analysis of regional heat wave warning using RegCM simulations

NASA Astrophysics Data System (ADS)

Pongracz, R.; Bartholy, J.; Bartha, E. B.; Torek, O.; Torma, Cs.

2010-09-01

Heat wave events are important temperature-related climatological extremes due to their impacts on human health. In the future, they are very likely to occur more frequently and more intensely not only in the Carpathian Basin, but in most regions of the world because of global warming. In order to develop adaptation and mitigation strategies on local scale, it is essential to analyze the projected changes related to heat waves. In Hungary, three categories of heat wave warning are applied. They are associated to the daily mean temperature values. (i) Warning category 1 is issued when the daily mean temperature is larger than 25 °C. (ii) Warning category 2 is issued when the daily mean temperature for at least 3 consecutive days is larger than 25 °C. (iii) Warning category 3 is issued when the daily mean temperature for at least 3 consecutive days is larger than 27 °C. In this poster, frequency of these conditions are analyzed using regional climate model experiments of model RegCM with 10-km horizontal resolution adapted at the Department of Meteorology, Eotvos Lorand University in the frame of the CECILIA EU-project. The model RegCM is a 3-dimensional, sigma-coordinate, primitive equation model, and it was originally developed by Giorgi et al. Currently, it is available from the ICTP (International Centre for Theoretical Physics). The initial and lateral boundary conditions of the fine-resolution experiments have been provided by the global climate model ECHAM for the A1B emission scenario for three different time slices (1961-1990, 2021-2050, and 2071-2100).

Application of Temperature-Dependent Fluorescent Dyes to the Measurement of Millimeter Wave Absorption in Water Applied to Biomedical Experiments

PubMed Central

Popenko, Oleksandr

2014-01-01

Temperature sensitivity of the fluorescence intensity of the organic dyes solutions was used for noncontact measurement of the electromagnetic millimeter wave absorption in water. By using two different dyes with opposite temperature effects, local temperature increase in the capillary that is placed inside a rectangular waveguide in which millimeter waves propagate was defined. The application of this noncontact temperature sensing is a simple and novel method to detect temperature change in small biological objects. PMID:25435859

Application of temperature-dependent fluorescent dyes to the measurement of millimeter wave absorption in water applied to biomedical experiments.

PubMed

Kuzkova, Nataliia; Popenko, Oleksandr; Yakunov, Andrey

2014-01-01

Temperature sensitivity of the fluorescence intensity of the organic dyes solutions was used for noncontact measurement of the electromagnetic millimeter wave absorption in water. By using two different dyes with opposite temperature effects, local temperature increase in the capillary that is placed inside a rectangular waveguide in which millimeter waves propagate was defined. The application of this noncontact temperature sensing is a simple and novel method to detect temperature change in small biological objects.

Coastal circulation and sediment dynamics in Hanalei Bay, Kauai. Part I: Measurements of waves, currents, temperature, salinity and turbidity : June - August, 2005

USGS Publications Warehouse

Storlazzi, Curt D.; Presto, M. Kathy; Logan, Joshua B.; Field, Michael E.

2006-01-01

Introduction: High-resolution measurements of waves, currents, water levels, temperature, salinity and turbidity were made in Hanalei Bay, northern Kauai, Hawaii, during the summer of 2005 to better understand coastal circulation and sediment dynamics in coral reef habitats. A series of bottom-mounted instrument packages were deployed in water depths of 10 m or less to collect long-term, high-resolution measurements of waves, currents, water levels, temperature, salinity and turbidity. These data were supplemented with a series of vertical instrument casts to characterize the vertical and spatial variability in water column properties within the bay. The purpose of these measurements was to collect hydrographic data to learn how waves, currents and water column properties vary spatially and temporally in an embayment that hosts a nearshore coral reef ecosystem adjacent to a major river drainage. These measurements support the ongoing process studies being conducted as part of the U.S. Geological Survey (USGS) Coastal and Marine Geology Program's Coral Reef Project; the ultimate goal is to better understand the transport mechanisms of sediment, larvae, pollutants and other particles in coral reef settings. This report, the first part in a series, describes data acquisition, processing and analysis.

Analysis of a jet stream induced gravity wave associated with an observed ice cloud over Greenland

NASA Astrophysics Data System (ADS)

Buss, S.; Hertzog, A.; Hostettler, C.; Bui, T. P.; Lüthi, T.; Wernli, H.

2003-11-01

A polar stratospheric ice cloud (PSC type II) was observed by airborne lidar above Greenland on 14 January 2000. Is was the unique observation of an ice cloud over Greenland during the SOLVE/THESEO 2000 campaign. Mesoscale simulations with the hydrostatic HRM model are presented which, in contrast to global analyses, are capable to produce a vertically propagating gravity wave that induces the low temperatures at the level of the PSC afforded for the ice formation. The simulated minimum temperature is ~8 K below the driving analyses and ~3 K below the frost point, exactly coinciding with the location of the observed ice cloud. Despite the high elevations of the Greenland orography the simulated gravity wave is not a mountain wave. Analyses of the horizontal wind divergence, of the background wind profiles, of backward gravity wave ray-tracing trajectories, of HRM experiments with reduced Greenland topography and of several instability diagnostics near the tropopause level provide consistent evidence that the wave is emitted by the geostrophic adjustment of a jet instability associated with an intense, rapidly evolving, anticyclonically curved jet stream. In order to evaluate the potential frequency of such non-orographic polar stratospheric cloud events, an approximate jet instability diagnostic is performed for the winter 1999/2000. It indicates that ice-PSCs are only occasionally generated by gravity waves emanating from an unstable jet.

Gravity wave characteristics in the middle atmosphere during the CESAR campaign at Palma de Mallorca in 2011/2012: Impact of extratropical cyclones and cold fronts

NASA Astrophysics Data System (ADS)

Kramer, R.; Wüst, S.; Schmidt, C.; Bittner, M.

2015-06-01

Based on a measuring campaign which was carried out at Mallorca (39.6°N, 2.7°E) as cooperation between Agència Estatal de Meteorologia (AEMET) and Deutsches Zentrum für Luft- und Raumfahrt, engl. 'German Aerospace Center' (DLR) in 2011/2012 (September-January), 143 radiosondes (day and night) providing vertical temperature and wind profiles were released. Additionally, nocturnal mesopause temperature measurements with a temporal resolution of about 1 min were conducted by the infrared (IR) - Ground-based Infrared P-branch Spectrometer (GRIPS) during the campaign period. Strongly enhanced gravity wave activity in the lower stratosphere is observed which can be attributed to a hurricane-like storm (so-called Medicane) and to passing by cold fronts. Statistical features of gravity wave parameters including energy densitiy and momentum fluxes are calculated. Gravity wave momentum fluxes turned out being up to five times larger during severe weather. Moreover, gravity wave horizontal propagation characteristics are derived applying hodograph and Stokes parameter analysis. Preferred directions are of southeast and northwest due to prevailing wind directions at Mallorca.

The role of local heating in the 2015 Indian Heat Wave.

PubMed

Ghatak, Debjani; Zaitchik, Benjamin; Hain, Christopher; Anderson, Martha

2017-08-09

India faced a major heat wave during the summer of 2015. Temperature anomalies peaked in the dry period before the onset of the summer monsoon, suggesting that local land-atmosphere feedbacks involving desiccated soils and vegetation might have played a role in driving the heat extreme. Upon examination of in situ data, reanalysis, satellite observations, and land surface models, we find that the heat wave included two distinct peaks: one in late May, and a second in early June. During the first peak we find that clear skies led to a positive net radiation anomaly at the surface, but there is no significant sensible heat flux anomaly within the core of the heat wave affected region. By the time of the second peak, however, soil moisture had dropped to anomalously low levels in the core heat wave region, net surface radiation was anomalously high, and a significant positive sensible heat flux anomaly developed. This led to a substantial local forcing on air temperature that contributed to the intensity of the event. The analysis indicates that the highly agricultural landscape of North and Central India can reinforce heat extremes under dry conditions.

Noise shielding by a hot subsonic jet

NASA Technical Reports Server (NTRS)

Vijayaraghavan, A.; Parthasarathy, S. P.

1981-01-01

An analysis is conducted of the shielding of the noise emitted by a high speed round jet by a hot, subsonic, semicircular jet. A plane wave front in the primary jet is resolved into elementary plane waves which undergo multiple reflections at the jet boundaries of the primary and the shielding jets. The jet boundaries are idealized to be vortex sheets. The far field sound is evaluated asymptotically by a superposition of the waves that penetrate the shielding jet. The angular directivities are plotted for several values of jet temperature and velocity to examine the effectiveness of shielding by the semicircular jet layer.

Nonlinear Internal Waves on the Inner Shelf: Observations Using a Distributed Temperature Sensing (DTS) System.

NASA Astrophysics Data System (ADS)

Davis, K. A.; Reid, E. C.; Cohen, A. L.

2016-02-01

Internal waves propagating across the continental slope and shelf are transformed by the competing effects of nonlinear steepening and dispersive spreading, forming nonlinear internal waves (NLIWs) that can penetrate onto the shallow inner shelf, often appearing in the form of bottom-propagating nonlinear internal bores or boluses. NLIWs play a significant role in nearshore dynamics with baroclinic current amplitudes on the order of that of wind- and surface wave-driven flows and rapid temperature changes on the order of annual ranges. In June 2014 we used a Distributed Temperature Sensing (DTS) system to give a continuous cross-shelf view of nonlinear internal wave dynamics on the forereef of Dongsha Atoll, a coral reef in the northern South China Sea. A DTS system measures temperature continuously along the length of an optical fiber, resolving meter-to-kilometer spatial scales. This unique view of cross-shelf temperature structure made it possible to observe internal wave reflection, variable propagation speed across the shelf, bolus formation and dissipation. Additionally, we used the DTS data to track internal waves across the shallow fore reef and onto the reef flat and to quantify spatial patterns in temperature variability. Shoaling internal waves are an important process affecting physical variability and water properties on the reef.

Fundamental plasma emission involving ion sound waves

NASA Technical Reports Server (NTRS)

Cairns, Iver H.

1987-01-01

The theory for fundamental plasma emission by the three-wave processes L + or - S to T (where L, S and T denote Langmuir, ion sound and transverse waves, respectively) is developed. Kinematic constraints on the characteristics and growth lengths of waves participating in the wave processes are identified. In addition the rates, path-integrated wave temperatures, and limits on the brightness temperature of the radiation are derived.

Expressions for the spherical-wave-structure function based on a bump spectrum model for the index of refraction

NASA Astrophysics Data System (ADS)

Richardson, Christina E.; Andrews, Larry C.

1991-07-01

New spectra models have recently been developed for the spatial power spectra of temperature and refractive index fluctuations in the atmospheric boundary layer showing the characteristic 'bump' just prior to the dissipation ranges. Theoretical work involving these new models has led to new expressions for the phase structure function associated with a plane optical wave, although most experimental work has involved spherical waves. Following techniques similar to those used for the plane wave analysis, new expressions valid in geometrical and diffraction regimes are developed here for the phase structure function of a spherical optical wave propagating through clear-air atmospheric turbulence. Useful asymptotic formulas for small separation distances and the inertial subrange are derived from these general expressions.

Comparing exposure metrics for classifying ‘dangerous heat’ in heat wave and health warning systems

PubMed Central

Zhang, Kai; Rood, Richard B.; Michailidis, George; Oswald, Evan M.; Schwartz, Joel D.; Zanobetti, Antonella; Ebi, Kristie L.; O’Neill, Marie S.

2012-01-01

Heat waves have been linked to excess mortality and morbidity, and are projected to increase in frequency and intensity with a warming climate. This study compares exposure metrics to trigger heat wave and health warning systems (HHWS), and introduces a novel multi-level hybrid clustering method to identify potential dangerously hot days. Two-level and three-level hybrid clustering analysis as well as common indices used to trigger HHWS, including spatial synoptic classification (SSC); and 90th, 95th, and 99th percentiles of minimum and relative minimum temperature (using a 10 day reference period), were calculated using a summertime weather dataset in Detroit from 1976 to 2006. The days classified as ‘hot’ with hybrid clustering analysis, SSC, minimum and relative minimum temperature methods differed by method type. SSC tended to include the days with, on average, 2.6 °C lower daily minimum temperature and 5.3 °C lower dew point than days identified by other methods. These metrics were evaluated by comparing their performance in predicting excess daily mortality. The 99th percentile of minimum temperature was generally the most predictive, followed by the three-level hybrid clustering method, the 95th percentile of minimum temperature, SSC and others. Our proposed clustering framework has more flexibility and requires less substantial meteorological prior information than the synoptic classification methods. Comparison of these metrics in predicting excess daily mortality suggests that metrics thought to better characterize physiological heat stress by considering several weather conditions simultaneously may not be the same metrics that are better at predicting heat-related mortality, which has significant implications in HHWSs. PMID:22673187

Temperature effects on the band gaps of Lamb waves in a one-dimensional phononic-crystal plate (L).

PubMed

Cheng, Y; Liu, X J; Wu, D J

2011-03-01

This study investigates the temperature-tuned band gaps of Lamb waves in a one-dimensional phononic-crystal plate, which is formed by alternating strips of ferroelectric ceramic Ba(0.7)Sr(0.3)TiO(3) and epoxy. The sensitive and continuous temperature-tunability of Lamb wave band gaps is demonstrated using the analyses of the band structures and the transmission spectra. The width and position of Lamb wave band gaps shift prominently with variation of temperature in the range of 26 °C-50 °C. For example, the width of the second band gap increases from 0.066 to 0.111 MHz as the temperature is increased from 26 °C to 50 °C. The strong shift promises that the structure could be suitable for temperature-tuned multi-frequency Lamb wave filters. © 2011 Acoustical Society of America

Control of the transition between regular and mach reflection of shock waves

NASA Astrophysics Data System (ADS)

Alekseev, A. K.

2012-06-01

A control problem was considered that makes it possible to switch the flow between stationary Mach and regular reflection of shock waves within the dual solution domain. The sensitivity of the flow was computed by solving adjoint equations. A control disturbance was sought by applying gradient optimization methods. According to the computational results, the transition from regular to Mach reflection can be executed by raising the temperature. The transition from Mach to regular reflection can be achieved by lowering the temperature at moderate Mach numbers and is impossible at large numbers. The reliability of the numerical results was confirmed by verifying them with the help of a posteriori analysis.

The 1994 heat wave in South Korea: mortality impacts and recurrence probability in a changing climate

NASA Astrophysics Data System (ADS)

Kysely, J.; Kim, J.

2010-03-01

The study deals with mortality impacts of the July-August 1994 heat wave in the population of South Korea, including the megacity of Seoul (with the population exceeding 10 million for the city and 20 million for the metropolitan area), and estimates recurrence probability of the heat wave in a changing climate in terms of simulations of daily temperature series with a stochastic model. The 1994 heat wave is found exceptional with respect to both climatological characteristics and the mortality effects: significantly elevated mortality occurred in all population groups, including children up to 14 years of age, and the total death toll exceeded 3000 in the Korean population, which ranks the 1994 heat wave among the worst weather-related disasters in East Asia. The estimate represents net excess mortality as no mortality displacement effect appeared. A comparison with other documented natural disasters shows that the death toll of the heat wave was much higher than those of the most disastrous floodings and typhoons over Korean Peninsula in the 20th century. The mortality response was stronger in males than females although males are found to be less vulnerable during average heat waves. A climatological analysis reveals that the July-August 1994 heat wave might be considered an extremely rare event with a return period in the order of hundreds of years if stationarity of temperature time series is assumed. However, under a more realistic assumption of gradual warming related to climate change, recurrence probability of an event analogous to the 1994 heat wave sharply rises for near-future time horizons. If warming of 0.04°C/year is assumed over 2001-2060, the recurrence interval of a very long spell of days with temperature exceeding a high threshold (as in the 1994 heat wave) is estimated to decrease to around 40 (10) years in the 2021-2030 (2041-2050) decade. This emphasizes the need for setting up an efficient heat-watch-warning system in this area in order to reduce human mortality impacts of heat waves.

The effects of pressure, temperature, and pore water on velocities in Westerly granite. [for seismic wave propagation

NASA Technical Reports Server (NTRS)

Spencer, J. W., Jr.; Nur, A. M.

1976-01-01

A description is presented of an experimental assembly which has been developed to conduct concurrent measurements of compressional and shear wave velocities in rocks at high temperatures and confining pressures and with independent control of the pore pressure. The apparatus was used in studies of the joint effects of temperature, external confining pressure, and internal pore water on sonic velocities in Westerly granite. It was found that at a given temperature, confining pressure has a larger accelerating effect on compressional waves in dry rock, whereas at a given confining pressure, temperature has a larger retarding effect on shear waves.

On the spatial stability of a liquid jet in the presence of vapor cavities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lü, Ming; Ning, Zhi, E-mail: zhining@bjtu.edu.cn; Lu, Mei

2013-11-15

A dispersion equation describing the effect of temperature differences on the stability of three-dimensional cylindrical liquid jets in the presence of vapor cavities is presented by the use of linear stability analysis. The mathematical model and its solving method are verified by comparing them with the data in the literature, and then the effect of temperature differences between jet and surrounding gas on the spatial stability of liquid jet is investigated. Some conclusions can be drawn from the results of this investigation: (1) the temperature difference destabilizes the liquid jet when the jet liquid is cooler than the surrounding gas,more » (2) the smallest atomized droplet without taking into account the effect of temperature differences is significantly larger than that when the effect of temperature differences is taken into account, (3) the effect of temperature differences on the stability of liquid jet has little relationship with azimuthal wave modes, (4) cavitation destabilizes the liquid jet when the value of the bubble volume fraction is not greater than 0.1 (0 ≤ α ≤ 0.1), and the temperature difference can weaken this effect of cavitation on the stability of liquid jet, and (5) cavitation is responsible for generating smaller droplets, the effect of cavitation on the critical wave number with and without taking into account the effect of temperature differences is quite different, and temperature difference is likely to fully restrain the effect of cavitation on the critical wave number; however, cavitation is again responsible for generating smaller droplets despite the effect of temperature differences when the bubble volume fraction α = 0.1. These findings may explain some observations of practical atomizer performance.« less

Analysis of a jet stream induced gravity wave associated with an observed stratospheric ice cloud over Greenland

NASA Astrophysics Data System (ADS)

Buss, S.; Hertzog, A.; Hostettler, C.; Bui, T. B.; Lüthi, D.; Wernli, H.

2004-08-01

A polar stratospheric ice cloud (PSC type II) was observed by airborne lidar above Greenland on 14 January 2000. It was the unique observation of an ice cloud over Greenland during the SOLVE/THESEO 2000 campaign. Mesoscale simulations with the hydrostatic HRM model are presented which, in contrast to global analyses, are capable to produce a vertically propagating gravity wave that induces the low temperatures at the level of the PSC afforded for the ice formation. The simulated minimum temperature is ~8 K below the driving analyses and ~4.5 K below the frost point, exactly coinciding with the location of the observed ice cloud. Despite the high elevations of the Greenland orography the simulated gravity wave is not a mountain wave. Analyses of the horizontal wind divergence, of the background wind profiles, of backward gravity wave ray-tracing trajectories, of HRM experiments with reduced Greenland topography and of several diagnostics near the tropopause level provide evidence that the wave is emitted from an intense, rapidly evolving, anticyclonically curved jet stream. The precise physical process responsible for the wave emission could not be identified definitely, but geostrophic adjustment and shear instability are likely candidates.

In order to evaluate the potential frequency of such non-orographic polar stratospheric cloud events, the non-linear balance equation diagnostic is performed for the winter 1999/2000. It indicates that ice-PSCs are only occasionally generated by gravity waves emanating from spontaneous adjustment.

Atmospheric planetary wave response to external forcing

NASA Technical Reports Server (NTRS)

Stevens, D. E.; Reiter, E. R.

1985-01-01

The tools of observational analysis, complex general circulation modeling, and simpler modeling approaches were combined in order to attack problems on the largest spatial scales of the earth's atmosphere. Two different models were developed and applied. The first is a two level, global spectral model which was designed primarily to test the effects of north-south sea surface temperature anomaly (SSTA) gradients between the equatorial and midlatitude north Pacific. The model is nonlinear, contains both radiation and a moisture budget with associated precipitation and surface evaporation, and utilizes a linear balance dynamical framework. Supporting observational analysis of atmospheric planetary waves is briefly summarized. More extensive general circulation models have also been used to consider the problem of the atmosphere's response, especially in the horizontal propagation of planetary scale waves, to SSTA.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jian, L. K.; Wei, H. Y.; Russell, C. T.

Transverse, near-circularly polarized, parallel-propagating electromagnetic waves around the proton cyclotron frequency were found sporadically in the solar wind throughout the inner heliosphere. They could play an important role in heating and accelerating the solar wind. These low-frequency waves (LFWs) are intermittent but often occur in prolonged bursts lasting over 10 minutes, named 'LFW storms'. Through a comprehensive survey of them from Solar Terrestrial Relations Observatory A using dynamic spectral wave analysis, we have identified 241 LFW storms in 2008, present 0.9% of the time. They are left-hand (LH) or right-hand (RH) polarized in the spacecraft frame with similar characteristics, probablymore » due to Doppler shift of the same type of waves or waves of intrinsically different polarities. In rare cases, the opposite polarities are observed closely in time or even simultaneously. Having ruled out interplanetary coronal mass ejections, shocks, energetic particles, comets, planets, and interstellar ions as LFW sources, we discuss the remaining generation scenarios: LH ion cyclotron instability driven by greater perpendicular temperature than parallel temperature or by ring-beam distribution, and RH ion fire hose instability driven by inverse temperature anisotropy or by cool ion beams. The investigation of solar wind conditions is compromised by the bias of the one-dimensional Maxwellian fit used for plasma data calibration. However, the LFW storms are preferentially detected in rarefaction regions following fast winds and when the magnetic field is radial. This preference may be related to the ion cyclotron anisotropy instability in fast wind and the minimum in damping along the radial field.« less

Dale Jenne | NREL

Science.gov Websites

and focuses on thermal system and economic analysis for low temperature and co-produced hydrothermal mechanical systems and economic analysis has led to his most recent work with the Marine and Hydrokinetic (MHK) team, where he is one of the lead techno-economic analysts for wave and current energy. His areas

Dust acoustic solitary waves in a dusty plasma with two kinds of nonthermal ions at different temperatures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dorranian, Davoud; Sabetkar, Akbar

The nonlinear dust acoustic solitary waves in a dusty plasma with two nonthermal ion species at different temperatures is studied analytically. Using reductive perturbation method, the Kadomtsev-Petviashivili (KP) equation is derived, and the effects of nonthermal coefficient, ions temperature, and ions number density on the amplitude and width of soliton in dusty plasma are investigated. It is shown that the amplitude of solitary wave of KP equation diverges at critical points of plasma parameters. The modified KP equation is also derived, and from there, the soliton like solutions of modified KP equation with finite amplitude is extracted. Results show thatmore » generation of rarefactive or compressive solitary waves strongly depends on the number and temperature of nonthermal ions. Results of KP equation confirm that for different magnitudes of ions temperature (mass) and number density, mostly compressive solitary waves are generated in a dusty plasma. In this case, the amplitude of solitary wave is decreased, while the width of solitary waves is increased. According to the results of modified KP equation for some certain magnitudes of parameters, there is a condition for generation of an evanescent solitary wave in a dusty plasma.« less

Marangoni instability in a thin film heated from below: Effect of nonmonotonic dependence of surface tension on temperature

NASA Astrophysics Data System (ADS)

Sarma, Rajkumar; Mondal, Pranab Kumar

2018-04-01

We investigate Marangoni instability in a thin liquid film resting on a substrate of low thermal conductivity and separated from the surrounding gas phase by a deformable free surface. Considering a nonmonotonic variation of surface tension with temperature, here we analytically derive the neutral stability curve for the monotonic and oscillatory modes of instability (for both the long-wave and short-wave perturbations) under the framework of linear stability analysis. For the long-wave instability, we derive a set of amplitude equations using the scaling k ˜(Bi) 1 /2 , where k is the wave number and Bi is the Biot number. Through this investigation, we demonstrate that for such a fluid layer upon heating from below, both monotonic and oscillatory instability can appear for a certain range of the dimensionless parameters, viz., Biot number (Bi ) , Galileo number (Ga ) , and inverse capillary number (Σ ) . Moreover, we unveil, through this study, the influential role of the above-mentioned parameters on the stability of the system and identify the critical values of these parameters above which instability initiates in the liquid layer.

Transition from geostrophic turbulence to inertia-gravity waves in the atmospheric energy spectrum.

PubMed

Callies, Jörn; Ferrari, Raffaele; Bühler, Oliver

2014-12-02

Midlatitude fluctuations of the atmospheric winds on scales of thousands of kilometers, the most energetic of such fluctuations, are strongly constrained by the Earth's rotation and the atmosphere's stratification. As a result of these constraints, the flow is quasi-2D and energy is trapped at large scales—nonlinear turbulent interactions transfer energy to larger scales, but not to smaller scales. Aircraft observations of wind and temperature near the tropopause indicate that fluctuations at horizontal scales smaller than about 500 km are more energetic than expected from these quasi-2D dynamics. We present an analysis of the observations that indicates that these smaller-scale motions are due to approximately linear inertia-gravity waves, contrary to recent claims that these scales are strongly turbulent. Specifically, the aircraft velocity and temperature measurements are separated into two components: one due to the quasi-2D dynamics and one due to linear inertia-gravity waves. Quasi-2D dynamics dominate at scales larger than 500 km; inertia-gravity waves dominate at scales smaller than 500 km.

Transition from geostrophic turbulence to inertia–gravity waves in the atmospheric energy spectrum

PubMed Central

Callies, Jörn; Ferrari, Raffaele; Bühler, Oliver

2014-01-01

Midlatitude fluctuations of the atmospheric winds on scales of thousands of kilometers, the most energetic of such fluctuations, are strongly constrained by the Earth’s rotation and the atmosphere’s stratification. As a result of these constraints, the flow is quasi-2D and energy is trapped at large scales—nonlinear turbulent interactions transfer energy to larger scales, but not to smaller scales. Aircraft observations of wind and temperature near the tropopause indicate that fluctuations at horizontal scales smaller than about 500 km are more energetic than expected from these quasi-2D dynamics. We present an analysis of the observations that indicates that these smaller-scale motions are due to approximately linear inertia–gravity waves, contrary to recent claims that these scales are strongly turbulent. Specifically, the aircraft velocity and temperature measurements are separated into two components: one due to the quasi-2D dynamics and one due to linear inertia–gravity waves. Quasi-2D dynamics dominate at scales larger than 500 km; inertia–gravity waves dominate at scales smaller than 500 km. PMID:25404349

Observations and Modeling of Thermal Structure in the Lower Atmosphere and the Upward Propagation of Tides into the Thermosphere

NASA Technical Reports Server (NTRS)

Wilson, R. J.; Kahre, M.

2017-01-01

Thermal tides are the atmospheric response to diurnally varying thermal forcing resulting from radiative and convective heat transfer from the surface and from aerosol and gaseous heating within the atmosphere. Tides include sun-synchronous (migrating) waves driven in response to solar heating and additional non-migrating waves resulting from longitudinal variations in the distributions of topography, dust aerosol and water ice clouds. The systematic spatial mapping of temperature over 5 Mars years by the Mars Climate Sounder (MCS) has yielded a well-defined climatology of seasonally-varying temperature structures in the lower atmosphere, from 5 to 80 km. Tide theory and Mars global circulation model (MGCM) simulations are a fruitful framework for relating temperature observations to thermal forcing by aerosol fields [1]. The analysis of density and temperature fields derived from MAVEN IUVS and NGIMS observations have revealed the presence of predominantly zonal wave 2 and 3 features at altitudes of 100-170 km that are almost certainly non-migrating tides propagating upward from the lower atmosphere [2,3]. In this presentation we will use the MCS climatology and MGCM simulations to relate the density variations seen by MAVEN with the seasonally varying tide activity in the lower atmosphere. Large amplitude perturbations in density are most sensitive to the tide components with the longest vertical wavelengths in temperature, which are well resolved in MCS observations.

On the wave number 2 eastward propagating quasi 2 day wave at middle and high latitudes

NASA Astrophysics Data System (ADS)

Gu, Sheng-Yang; Liu, Han-Li; Pedatella, N. M.; Dou, Xiankang; Liu, Yu

2017-04-01

The temperature and wind data sets from the ensemble data assimilation version of the Whole Atmosphere Community Climate Model + Data Assimilation Research Testbed (WACCM + DART) developed at the National Center for Atmospheric Research (NCAR) are utilized to study the seasonal variability of the eastward quasi 2 day wave (QTDW) with zonal wave number 2 (E2) during 2007. The aliasing ratio of E2 from wave number 3 (W3) in the synoptic WACCM data set is a constant value of 4 × 10-6% due to its uniform sampling pattern, whereas the aliasing is latitudinally dependent if the WACCM fields are sampled asynoptically based on the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) sampling. The aliasing ratio based on SABER sampling is 75% at 40°S during late January, where and when W3 peaks. The analysis of the synoptic WACCM data set shows that the E2 is in fact a winter phenomenon, which peaks in the stratosphere and lower mesosphere at high latitudes. In the austral winter period, the amplitudes of E2 can reach 10 K, 20 m/s, and 30 m/s for temperature, zonal, and meridional winds, respectively. In the boreal winter period, the wave perturbations are only one third as strong as those in austral winter. Diagnostic analysis also shows that the mean flow instabilities in the winter upper mesosphere polar region provide sources for the amplification of E2. This is different from the westward QTDWs, whose amplifications are related to the summer easterly jet. In addition, the E2 also peaks at lower altitude than the westward modes.

Global Ray Tracing Simulations of the SABER Gravity Wave Climatology

DTIC Science & Technology

2009-01-01

atmosphere , the residual temperature profiles are analyzed by a combi- nation of maximum entropy method (MEM) and harmonic analysis, thus providing the...accepted 24 February 2009; published 30 April 2009. [1] Since February 2002, the SABER (sounding of the atmosphere using broadband emission radiometry...satellite instrument has measured temperatures throughout the entire middle atmosphere . Employing the same techniques as previously used for CRISTA

Temperature measurement using ultraviolet laser absorption of carbon dioxide behind shock waves.

PubMed

Oehlschlaeger, Matthew A; Davidson, David F; Jeffries, Jay B

2005-11-01

A diagnostic for microsecond time-resolved temperature measurements behind shock waves, using ultraviolet laser absorption of vibrationally hot carbon dioxide, is demonstrated. Continuous-wave laser radiation at 244 and 266 nm was employed to probe the spectrally smooth CO2 ultraviolet absorption, and an absorbance ratio technique was used to determine temperature. Measurements behind shock waves in both nonreacting and reacting (ignition) systems were made, and comparisons with isentropic and constant-volume calculations are reported.

Dispersive charge density wave excitations in Bi 2Sr 2CaCu 2O 8+δ [Dispersive charge density wave excitations and temperature dependent commensuration in Bi 2Sr 2CaCu 2O 8+δ

DOE PAGES

Chaix, L.; Ghiringhelli, G.; Peng, Y. Y.; ...

2017-06-12

Experimental evidence on high-T c cuprates reveals ubiquitous charge density wave (CDW) modulations, which coexist with superconductivity. Although the CDW had been predicted by theory, important questions remain about the extent to which the CDW influences lattice and charge degrees of freedom and its characteristics as functions of doping and temperature. These questions are intimately connected to the origin of the CDW and its relation to the mysterious cuprate pseudogap. We use ultrahigh-resolution resonant inelastic X-ray scattering to reveal new CDW character in underdoped Bi 2.2Sr 1.8Ca 0.8Dy 0.2Cu 2O 8+δ. At low temperature, we observe dispersive excitations from anmore » incommensurate CDW that induces anomalously enhanced phonon intensity, unseen using other techniques. Furthermore, near the pseudogap temperature T*, the CDW persists, but the associated excitations significantly weaken with an indication of CDW wavevector shift. The dispersive CDW excitations, phonon anomaly, and analysis of the CDW wavevector provide a comprehensive momentum-space picture of complex CDW behaviour and point to a closer relationship with the pseudogap state.« less

Electrically-Active Convection and Tropical Cyclogenesis in the Atlantic and East Pacific

NASA Technical Reports Server (NTRS)

Leppert, Kenneth D., II; Petersen, Walter A.

2010-01-01

It has been hypothesized that deep, intense convective-scale "hot" towers may aid the process of tropical cyclogenesis and intensification through dynamic and thermodynamic feedbacks on the larger meso-to-synoptic scale circulation. In this study, we make use of NCEP Reanalysis data and Tropical Rainfall Measurement Mission (TRMM) lightning imaging sensor (LIS), precipitation radar (PR), and microwave imager (TMI) data to investigate the role that widespread and/or intense lightning-producing convection (i.e., "electrically-hot towers") present in African easterly waves (AEWs) may play in tropical cyclogenesis over the Atlantic, Caribbean, and East Pacific regions. NCEP Reanalysis 700 hPa meridional winds for the months of June to November for the years 2001-2009 were analyzed for the domain of 5degN-20degN and 130degW-20degE in order to partition individual AEWs into northerly, southerly, trough, and ridge phases. Subsequently, information from National Hurricane Center (NHC) storm reports was used to divide the waves into developing and non-developing waves and to further divide the developing waves into those waves that spawned storms that only developed to tropical storm strength and those that spawned storms that reached hurricane strength. The developing waves were also divided by the region in which they developed. To help determine the gross nature of the smaller convective scale, composites were created of all developing and non-developing waves as a function of AEW wave phase over the full analysis domain and over various smaller longitude bands by compositing TRMM PR, TMI, LIS, and IR brightness temperature data extracted from the NASA global-merged IR brightness temperature dataset. Finally, similar composites were created using various NCEP variables to assess the nature of the larger scale environment and circulation. Results suggest a clear distinction between developing and non-developing waves as developing waves near their region of development in terms of the intensity of convection (indicated by lightning flash rate), coverage of cold cloudiness (indicated by the percentage of a 2.5deg by 2.5deg box covered by IR brightness temperatures less than 210 K), and large-scale variables, such as midlevel moisture and upper-level upward motion. For example, waves that developed in the East Pacific longitude band (i.e., 130degW-95degW) were observed in that band to have a flash rate of 56.4 flashes/day, a coverage by brightness temperatures less than 210 K equal to 2.2%, a 700-hPa specific humidity anomaly of 0.4 g/kg, and a 300-hPa omega value of -0.04 Pascals/s in the trough phase compared to the non-developing wave trough values of 22.1 flashes/day, a coverage by brightness temperatures less than 210 K equal to 0.9%, a 700-hPa specific humidity anomaly of -0.3 g/kg, and a 300-hPa omega value of -0.01 Pascals/s.

Heat waves measured with MODIS land surface temperature data predict changes in avian community structure

Treesearch

Thomas P. Albright; Anna M. Pidgeon; Chadwick D. Rittenhouse; Murray K. Clayton; Curtis H. Flather; Patrick D. Culbert; Volker C. Radeloff

2011-01-01

Heat waves are expected to become more frequent and severe as climate changes, with unknown consequences for biodiversity. We sought to identify ecologically-relevant broad-scale indicators of heat waves based on MODIS land surface temperature (LST) and interpolated air temperature data and assess their associations with avian community structure. Specifically, we...

Imaging Gravity Waves in Lower Stratospheric AMSU-A Radiances. Part 1: Simple Forward Model

DTIC Science & Technology

2006-08-14

brightening” of microwave radiances acquired from purely vertical background temperature profiles by cross- track scanners. Waves propagating along track...three-dimensional wave fields. For example, some limb sensors return high- resolution vertical temperature profiles with wave oscilla- tions...provide only ver- tical profiles of wave oscillations, similar to radiosonde and rocketsonde data. Similarly, limb-tracking measurements from the

Sahelian springtime heat waves and their evolution over the past 60 years

NASA Astrophysics Data System (ADS)

Barbier, Jessica; Guichard, Françoise; Bouniol, Dominique; Couvreux, Fleur; Roehrig, Romain

2017-04-01

The Sahel is a semi-arid region which experiences very high temperature both during day- and night-times: monthly-mean temperatures in Spring typically oscillate between 30 and 40°C. At the same time a strong climatic warming has been observed over the past 60 years in this region: it reaches +1,5°C over April-May. Thus heat waves in this region have severe impacts on health, ecosystem, agriculture and more broadly economical activities, which will probably worsen in the context of climate change. However, heat waves in the Sahel remain poorly studied. The present work documents Sahelian heat waves and assesses their evolution across the last 60 years. Properties of heat waves are sensitive to the way they are detected. Here, we use a methodology based on anomalies that allows to filter the seasonal, inter-annual and climatic evolutions, using a percentile-type threshold. It is applied separately to daily maximum and minimum temperatures and leads to two types of heat waves: day- and night-time ones. This separation matters because physical processes linked to minimum and maximum temperatures can be quite distinct. The changes in both types of heat wave were studied over the period 1950-2012 using the Berkeley Earth Surface Temperature gridded product: several heat wave characteristics were investigated, including morphological ones such as the length and the spatial extent of the event, the heat wave intensity and the associated warming trends. We found no significant trends in the frequency, duration and spatial extent of both types of heat waves, while on the other hand their maximum and minimum temperatures displayed significant positive trends. They were mainly explained by the regional warming. By contrast, with a standard climatic heat index using percentile-threshold on raw temperatures, both day- and night-time heat wave frequencies were increasing, and while the day-time heat waves were getting longer and larger, the night-time heat waves were getting hotter. The explanations for the differences between the heat indexes will be discussed. The ability of the three reanalyses ERA-Interim, NCEP2 and MERRA to reproduce Sahelian heat wave properties and their associated trends was further assessed on the period 1979-2010. At this shorter scale, we did not find any significant heat wave trend. Furthermore, reanalyses strongly differed in the representation of the heat wave inter-annual variability. These results raise concern about the utilization of meteorological reanalyses for the study of heat wave trends in West Africa.

The East Atlantic - West Russia Teleconnection in the North Atlantic: Climate Impact and Relation to Rossby Wave Propagation

NASA Technical Reports Server (NTRS)

Lim, Young-Kwon

2014-01-01

Large-scale winter teleconnection of the East Atlantic - West Russia (EA-WR) over the Atlantic and surrounding regions is examined in order to quantify its impacts on temperature and precipitation and identify the physical mechanisms responsible for its existence. A rotated empirical orthogonal function (REOF) analysis of the upper-tropospheric monthly height field captures successfully the EA-WR pattern and its interannual variation, with the North Atlantic Oscillation as the first mode. EA-WRs climate impact extends from eastern North America to Eurasia. The positive (negative) EA-WR produces positive (negative) temperature anomalies over the eastern US, western Europe and Russia east of Caspian Sea, with negative (positive) anomalies over eastern Canada, eastern Europe including Ural Mountains and the Middle East. These anomalies are largely explained by lower-tropospheric temperature advections. Positive (negative) precipitation anomalies are found over the mid-latitude Atlantic and central Russia around 60E, where lower-level cyclonic (anticyclonic) circulation anomaly is dominant. The eastern Canada and the western Europe are characterized by negative (positive) precipitation anomalies.The EA-WR is found to be closely associated with Rossby wave propagation. Wave activity fluxes show that it is strongly tied to large-scale stationary waves. Furthermore, a stationary wave model (SWM) forced with vorticity transients in the mid-latitude Atlantic (approximately 40N) or diabatic heat source over the subtropical Atlantic near the Caribbean Sea produces well-organized EA-WR-like wave patterns, respectively. Sensitivity tests with the SWM indicate improvement in the simulation of the EA-WR when the mean state is modified to have a positive NAO component that enhances upper-level westerlies between 40-60N.

Temperature-mediated transition from Dyakonov-Tamm surface waves to surface-plasmon-polariton waves

NASA Astrophysics Data System (ADS)

Chiadini, Francesco; Fiumara, Vincenzo; Mackay, Tom G.; Scaglione, Antonio; Lakhtakia, Akhlesh

2017-08-01

The effect of changing the temperature on the propagation of electromagnetic surface waves (ESWs), guided by the planar interface of a homogeneous isotropic temperature-sensitive material (namely, InSb) and a temperature-insensitive structurally chiral material (SCM) was numerically investigated in the terahertz frequency regime. As the temperature rises, InSb transforms from a dissipative dielectric material to a dissipative plasmonic material. Correspondingly, the ESWs transmute from Dyakonov-Tamm surface waves into surface-plasmon-polariton waves. The effects of the temperature change are clearly observed in the phase speeds, propagation distances, angular existence domains, multiplicity, and spatial profiles of energy flow of the ESWs. Remarkably large propagation distances can be achieved; in such instances the energy of an ESW is confined almost entirely within the SCM. For certain propagation directions, simultaneous excitation of two ESWs with (i) the same phase speeds but different propagation distances or (ii) the same propagation distances but different phase speeds are also indicated by our results.

Terahertz generation by beating two Langmuir waves in a warm and collisional plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Xiao-Bo; Qiao, Xin; Cheng, Li-Hong

2015-09-15

Terahertz (THz) radiation generated by beating of two Langmuir waves in a warm and collisional plasma is discussed theoretically. The critical angle between the two Langmuir waves and the critical wave-length (wave vector) of Langmuir waves for generating THz radiation are obtained analytically. Furthermore, the maximum radiation energy is obtained. We find that the critical angle, the critical wave-length, and the generated radiation energy strongly depend on plasma temperature and wave-length of the Langmuir waves. That is, the THz radiation generated by beating of two Langmuir waves in a warm and collisional plasma can be controlled by adjusting the plasmamore » temperature and the Langmuir wave-length.« less

Statistical analysis of suprathermal electron drivers at 67P/Churyumov-Gerasimenko

NASA Astrophysics Data System (ADS)

Broiles, Thomas W.; Burch, J. L.; Chae, K.; Clark, G.; Cravens, T. E.; Eriksson, A.; Fuselier, S. A.; Frahm, R. A.; Gasc, S.; Goldstein, R.; Henri, P.; Koenders, C.; Livadiotis, G.; Mandt, K. E.; Mokashi, P.; Nemeth, Z.; Odelstad, E.; Rubin, M.; Samara, M.

2016-11-01

We use observations from the Ion and Electron Sensor (IES) on board the Rosetta spacecraft to study the relationship between the cometary suprathermal electrons and the drivers that affect their density and temperature. We fit the IES electron observations with the summation of two kappa distributions, which we characterize as a dense and warm population (˜10 cm-3 and ˜16 eV) and a rarefied and hot population (˜0.01 cm-3 and ˜43 eV). The parameters of our fitting technique determine the populations' density, temperature, and invariant kappa index. We focus our analysis on the warm population to determine its origin by comparing the density and temperature with the neutral density and magnetic field strength. We find that the warm electron population is actually two separate sub-populations: electron distributions with temperatures above 8.6 eV and electron distributions with temperatures below 8.6 eV. The two sub-populations have different relationships between their density and temperature. Moreover, the two sub-populations are affected by different drivers. The hotter sub-population temperature is strongly correlated with neutral density, while the cooler sub-population is unaffected by neutral density and is only weakly correlated with magnetic field strength. We suggest that the population with temperatures above 8.6 eV is being heated by lower hybrid waves driven by counterstreaming solar wind protons and newly formed, cometary ions created in localized, dense neutral streams. To the best of our knowledge, this represents the first observations of cometary electrons heated through wave-particle interactions.

Brillouin-scattering measurements of surface-acoustic-wave velocities in silicon at high temperatures

NASA Astrophysics Data System (ADS)

Stoddart, P. R.; Comins, J. D.; Every, A. G.

1995-06-01

Brillouin-scattering measurements of the angular dependence of surface-acoustic-wave velociites at high temperatures are reported. The measurements have been performed on the (001) surface of a silicon single crystal at temperatures up to 800 °C, allowing comparison of the results with calculated velocities based on existing data for the elastic constants and thermal expansion of silicon in this temperature range. The change in surface-acoustic-wave velocity with temperature is reproduced well, demonstrating the value of this technique for the characterization of the high-temperature elastic properties of opaque materials.

Properties of a Laser Shock Wave in Al-Cu Alloy under Elevated Temperatures: A Molecular Dynamics Simulation Study

PubMed Central

Meng, Xiankai; Zhou, Jianzhong; Huang, Shu; Su, Chun; Sheng, Jie

2017-01-01

The laser shock wave (LSW) generated by the interaction between a laser and a material has been widely used in laser manufacturing, such as laser shock peening and laser shock forming. However, due to the high strain rate, the propagation of LSW in materials, especially LSW at elevated temperatures, is difficult to study through experimental methods. A molecular dynamics simulation was used in this study to investigate the propagation of LSW in an Al-Cu alloy. The Hugoniot relations of LSW were obtained at different temperatures and the effects of elevated temperatures on shock velocity and shock pressure were analyzed. Then the elastic and plastic wave of the LSW was researched. Finally, the evolution of dislocations induced by LSW and its mechanism under elevated temperatures was explored. The results indicate that the shock velocity and shock pressure induced by LSW both decrease with the increasing temperatures. Moreover, the velocity of elastic wave and plastic wave both decrease with the increasing treatment temperature, while their difference decreases as the temperature increases. Moreover, the dislocation atoms increases with the increasing temperatures before 2 ps, while it decreases with the increasing temperatures after 2 ps. The reason for the results is related to the formation and evolution of extended dislocations. PMID:28772433

Properties of a Laser Shock Wave in Al-Cu Alloy under Elevated Temperatures: A Molecular Dynamics Simulation Study.

PubMed

Meng, Xiankai; Zhou, Jianzhong; Huang, Shu; Su, Chun; Sheng, Jie

2017-01-18

The laser shock wave (LSW) generated by the interaction between a laser and a material has been widely used in laser manufacturing, such as laser shock peening and laser shock forming. However, due to the high strain rate, the propagation of LSW in materials, especially LSW at elevated temperatures, is difficult to study through experimental methods. A molecular dynamics simulation was used in this study to investigate the propagation of LSW in an Al-Cu alloy. The Hugoniot relations of LSW were obtained at different temperatures and the effects of elevated temperatures on shock velocity and shock pressure were analyzed. Then the elastic and plastic wave of the LSW was researched. Finally, the evolution of dislocations induced by LSW and its mechanism under elevated temperatures was explored. The results indicate that the shock velocity and shock pressure induced by LSW both decrease with the increasing temperatures. Moreover, the velocity of elastic wave and plastic wave both decrease with the increasing treatment temperature, while their difference decreases as the temperature increases. Moreover, the dislocation atoms increases with the increasing temperatures before 2 ps, while it decreases with the increasing temperatures after 2 ps. The reason for the results is related to the formation and evolution of extended dislocations.

Global Observation of Planetary-Scale Waves in UARS HRDI and WINDII MLT Winds

NASA Technical Reports Server (NTRS)

Lieberman, Ruth

1999-01-01

The purpose of this study is to use examine planetary-scale motions in the UARS mesosphere and lower thermospheric data. The actual study was confined to HRDI winds and temperatures, since these observations were more continuous, and spanned the 60-120 km range. Three classes of waves were studied: fast equatorial Kelvin waves, nonmigrating tides, and the midlatitude 2-day wave. The purpose of the Kelvin wave and the 2-day wave studies was to test whether the waves significantly affect the mean flow. Such studies require high-quality spectral definitions in order to derive the wave heat and momentum flux divergence which can act in comination to drive the mean flow. Accordingly, HRDI winds from several special observing campaigns were used for analyses of fast (periods under 5 days) waves. The campaigns are characterized by continuous viewing by HRDI in 2 viewing directions, for periods of 10-12 days. Data sampled in this manner lend themselves quite well to "asynoptic spectral analysis", from which motions with periods as low as one day can be retrieved with relatively minimal aliasing.

Nonlinear Electron Acoustic Waves in the Inner Magnetosphere

NASA Astrophysics Data System (ADS)

Dillard, C. S.; Vasko, I.; Mozer, F.; Agapitov, O. V.

2017-12-01

The Van Allen Probes observe intense broad-band electrostatic wave activity in the inner magnetosphere. The high-resolution electric field measurements show that these broad-band wave activity is made of large-amplitude electrostatic solitary waves propagating generally along the background magnetic field with velocities of a few thousands km/s. There are generally two types of the observed solitary waves. The solitary waves with the bipolar parallel electric field are interpreted as electron phase space holes, while the nature of solitary waves with asymmetric parallel electric field has remained puzzling. In the present work we show that asymmetric solitary waves propagate with velocities (1000-5000 km/s) and have spatial scales (100 m-1 km) similar to those for electron-acoustic waves existing due to two temperature electron population. Through the numerical fluid simulation we show that the spikes are produced from the initially harmonic electron-acoustic perturbation due to the nonlinear steepening. Through the analysis of the modified KdV equation we show that the steepening is arrested at some moment by the collisionless Landau dissipation and results in formation of the observed asymmetric spikes (shocklets).

A Simulated Heat Wave Has Diverse Effects on Immune Function and Oxidative Physiology in the Corn Snake (Pantherophis guttatus).

PubMed

Stahlschmidt, Z R; French, S S; Ahn, A; Webb, A; Butler, M W

Animals will continue to encounter increasingly warm environments, including more frequent and intense heat waves. Yet the physiological consequences of heat waves remain equivocal, potentially because of variation in adaptive plasticity (reversible acclimation) and/or aspects of experimental design. Thus, we measured a suite of physiological variables in the corn snake (Pantherophis guttatus) after exposure to field-parameterized, fluctuating temperature regimes (moderate temperature and heat wave treatments) to address two hypotheses: (1) a heat wave causes physiological stress, and (2) thermal performance of immune function exhibits adaptive plasticity in response to a heat wave. We found little support for our first hypothesis because a simulated heat wave had a negative effect on body mass, but it also reduced oxidative damage and did not affect peak performance of three immune metrics. Likewise, we found only partial support for our second hypothesis. After exposure to a simulated heat wave, P. guttatus exhibited greater performance breadth and reduced temperature specialization (the standardized difference between peak performance and performance breadth) for only one of three immune metrics and did so in a sex-dependent manner. Further, a simulated heat wave did not elicit greater performance of any immune metric at higher temperatures. Yet a heat wave likely reduced innate immune function in P. guttatus because each metric of innate immune performance in this species (as in most vertebrates) was lower at elevated temperatures. Together with previous research, our study indicates that a heat wave may have complex, modest, and even positive physiological effects in some taxa.

Dual demodulation interferometer with two-wave mixing in GaAs photorefractive crystal

NASA Astrophysics Data System (ADS)

Zhenzhen, Zhang; Zhongqing, Jia; Guangrong, Ji; Qiwu, Wang

2018-07-01

A dual demodulation interferometer with two-wave mixing (TWM) in the GaAs photorefractive crystal (PRC) is proposed and experimentally demonstrated. The GaAs PRC has tiny temperature change under high voltage thus not requiring thermoelectric cooler (TEC) to stabilize the temperature, and adaptive to low frequency fluctuation below 200 Hz. The system is an unbalanced TWM interferometer, which could demodulate the phase change both space variation and wavelength shift induced by strain. Two demodulation modes' formulas are provided in theory respectively. Experimental results have been tested and compared with theoretical analysis, demonstrating that it is a practical and flexible system for detection of mechanical vibration or structure health monitoring (SHM) in engineering by selecting different demodulation mode.

High temperature superconductor analog electronics for millimeter-wavelength communications

NASA Technical Reports Server (NTRS)

Romanofsky, R. R.; Bhasin, K. B.

1991-01-01

The performance of high temperature superconductor (HTS) passive microwave circuits up to X-band was encouraging when compared to their metallic counterparts. The extremely low surface resistance of HTS films up to about 10 GHz enables a reduction in loss by as much as 100 times compared to copper when both materials are kept at about 77 K. However, a superconductor's surface resistance varies in proportion to the frequency squared. Consequently, the potential benefit of HTS materials to millimeter-wave communications requires careful analysis. A simple ring resonator was used to evaluate microstrip losses at Ka-band. Additional promising components were investigated such as antennas and phase shifters. Prospects for HTS to favorable impact millimeter-wave communications systems are discussed.

Mathematical analysis of thermal diffusion shock waves

NASA Astrophysics Data System (ADS)

Gusev, Vitalyi; Craig, Walter; Livoti, Roberto; Danworaphong, Sorasak; Diebold, Gerald J.

2005-10-01

Thermal diffusion, also known as the Ludwig-Soret effect, refers to the separation of mixtures in a temperature gradient. For a binary mixture the time dependence of the change in concentration of each species is governed by a nonlinear partial differential equation in space and time. Here, an exact solution of the Ludwig-Soret equation without mass diffusion for a sinusoidal temperature field is given. The solution shows that counterpropagating shock waves are produced which slow and eventually come to a halt. Expressions are found for the shock time for two limiting values of the starting density fraction. The effects of diffusion on the development of the concentration profile in time and space are found by numerical integration of the nonlinear differential equation.

Warming set stage for deadly heat wave

NASA Astrophysics Data System (ADS)

Schultz, Colin

2012-04-01

In the summer of 2010, soaring temperatures and widespread forest fires ravaged western Russia, killing 55,000 and causing $15 billion in economic losses. In the wake of the record-setting heat wave, two studies sought to identify the contribution that human activities made to the event. One showed that temperatures seen during the deadly heat wave fell within the bounds of natural variability, while another attributed the heat wave to human activity, arguing that anthropogenic warming increased the chance of record-breaking temperatures occurring. Merging the stances of both studies, Otto et al. sought to show that while human contributions to climate change did not necessarily cause the deadly heat wave, they did play a role in setting the stage for its occurrence. Using an ensemble of climate simulations, the authors assessed the expected magnitude and frequency of an event like the 2010 heat wave under both 1960s and 2000s environmental conditions. The authors found that although the average temperature in July 2010 was 5°C higher than the average July temperature from the past half decade, the deadly heat wave was within the natural variability of 1960s, as well as 2000s, climate conditions

Thermal Cracking in Westerly Granite Monitored Using Direct Wave Velocity, Coda Wave Interferometry, and Acoustic Emissions

NASA Astrophysics Data System (ADS)

Griffiths, L.; Lengliné, O.; Heap, M. J.; Baud, P.; Schmittbuhl, J.

2018-03-01

To monitor both the permanent (thermal microcracking) and the nonpermanent (thermo-elastic) effects of temperature on Westerly Granite, we combine acoustic emission monitoring and ultrasonic velocity measurements at ambient pressure during three heating and cooling cycles to a maximum temperature of 450°C. For the velocity measurements we use both P wave direct traveltime and coda wave interferometry techniques, the latter being more sensitive to changes in S wave velocity. During the first cycle, we observe a high acoustic emission rate and large—and mostly permanent—apparent reductions in velocity with temperature (P wave velocity is reduced by 50% of the initial value at 450°C, and 40% upon cooling). Our measurements are indicative of extensive thermal microcracking during the first cycle, predominantly during the heating phase. During the second cycle we observe further—but reduced—microcracking, and less still during the third cycle, where the apparent decrease in velocity with temperature is near reversible (at 450°C, the P wave velocity is decreased by roughly 10% of the initial velocity). Our results, relevant for thermally dynamic environments such as geothermal reservoirs, highlight the value of performing measurements of rock properties under in situ temperature conditions.

Ash reduction system using electrically heated particulate matter filter

DOEpatents

Gonze, Eugene V [Pinckney, MI; Paratore, Jr., Michael J; He, Yongsheng [Sterling Heights, MI

2011-08-16

A control system for reducing ash comprises a temperature estimator module that estimates a temperature of an electrically heated particulate matter (PM) filter. A temperature and position estimator module estimates a position and temperature of an oxidation wave within the electrically heated PM filter. An ash reduction control module adjusts at least one of exhaust flow, fuel and oxygen levels in the electrically heated PM filter to adjust a position of the oxidation wave within the electrically heated PM filter based on the oxidation wave temperature and position.

Increasing probability of mortality during Indian heat waves.

PubMed

Mazdiyasni, Omid; AghaKouchak, Amir; Davis, Steven J; Madadgar, Shahrbanou; Mehran, Ali; Ragno, Elisa; Sadegh, Mojtaba; Sengupta, Ashmita; Ghosh, Subimal; Dhanya, C T; Niknejad, Mohsen

2017-06-01

Rising global temperatures are causing increases in the frequency and severity of extreme climatic events, such as floods, droughts, and heat waves. We analyze changes in summer temperatures, the frequency, severity, and duration of heat waves, and heat-related mortality in India between 1960 and 2009 using data from the India Meteorological Department. Mean temperatures across India have risen by more than 0.5°C over this period, with statistically significant increases in heat waves. Using a novel probabilistic model, we further show that the increase in summer mean temperatures in India over this period corresponds to a 146% increase in the probability of heat-related mortality events of more than 100 people. In turn, our results suggest that future climate warming will lead to substantial increases in heat-related mortality, particularly in developing low-latitude countries, such as India, where heat waves will become more frequent and populations are especially vulnerable to these extreme temperatures. Our findings indicate that even moderate increases in mean temperatures may cause great increases in heat-related mortality and support the efforts of governments and international organizations to build up the resilience of these vulnerable regions to more severe heat waves.

Experimental and Numerical Investigation of Internal Gravity Waves Excited by Turbulent Penetrative Convection in Water Around Its Density Maximum

NASA Astrophysics Data System (ADS)

Perrard, Stéphane; Le Bars, Michaël; Le Gal, Patrice

This study is devoted to the experimental and numerical analysis of the excitation of gravity waves by turbulent convection. This situation is representative of many geophysical or astrophysical systems such as the convective bottom layer of the atmosphere that radiates internal waves in the stratosphere, or the interaction between the convective and the radiative zones in stars. In our experiments, we use water as a working fluid as it possesses the remarkable property of having a maximum density at 4 °C. Therefore, when establishing on a water layer a temperature gradient between 0 °C at the bottom and room temperature at the top, a turbulent convective region appears spontaneously under a stably stratified zone. In these conditions, gravity waves are excited by the convective fluid motions penetrating the stratified layer. Although this type of flow, called penetrative convection, has already been described, we present here the first velocity field measurement of wave emission and propagation. We show in particular that an intermediate layer that we call the buffer layer emerges between the convective and the stratified zones. In this buffer layer, the angle of propagation of the waves varies with the altitude since it is slaved to the Brunt-Väisälä frequency which evolves rapidly between the convective and the stratified layer. A minimum angle is reached at the end of the buffer layer. Then we observe that an angle of propagation is selected when the waves travel through the stratified layer. We expect this process of wave selection to take place in natural situations.

Non-equilibrium Numerical Analysis of Microwave-supported Detonation Threshold Propagating through Diatomic Gas

NASA Astrophysics Data System (ADS)

Shiraishi, Hiroyuki

2015-09-01

Microwave-supported Detonation (MSD), one type of Microwave-supported Plasma (MSP), is considered as one of the most important phenomena because it can generate high pressure and high temperature for beam-powered space propulsion systems. In this study, I numerically simulate MSD waves propagating through a diatomic gas. In order to evaluate the threshold of beam intensity, I use the physical-fluid dynamics scheme, which has been developed for simulating unsteady and non-equilibrium LSD waves propagating through a hydrogen gas.

Implications of pressure diffusion for shock waves

NASA Technical Reports Server (NTRS)

Ram, Ram Bachan

1989-01-01

The report deals with the possible implications of pressure diffusion for shocks in one dimensional traveling waves in an ideal gas. From this new hypothesis all aspects of such shocks can be calculated except shock thickness. Unlike conventional shock theory, the concept of entropy is not needed or used. Our analysis shows that temperature rises near a shock, which is of course an experimental fact; however, it also predicts that very close to a shock, density increases faster than pressure. In other words, a shock itself is cold.

Monitoring and analysis of thermal deformation waves with a high-speed phase measurement system.

PubMed

Taylor, Lucas; Talghader, Joseph

2015-10-20

Thermal effects in optical substrates are vitally important in determining laser damage resistance in long-pulse and continuous-wave laser systems. Thermal deformation waves in a soda-lime-silica glass substrate have been measured using high-speed interferometry during a series of laser pulses incident on the surface. Two-dimensional images of the thermal waves were captured at a rate of up to six frames per thermal event using a quantitative phase measurement method. The system comprised a Mach-Zehnder interferometer, along with a high-speed camera capable of up to 20,000 frames-per-second. The sample was placed in the interferometer and irradiated with 100 ns, 2 kHz Q-switched pulses from a high-power Nd:YAG laser operating at 1064 nm. Phase measurements were converted to temperature using known values of thermal expansion and temperature-dependent refractive index for glass. The thermal decay at the center of the thermal wave was fit to a function derived from first principles with excellent agreement. Additionally, the spread of the thermal distribution over time was fit to the same function. Both the temporal decay fit and the spatial fit produced a thermal diffusivity of 5×10^-7  m²/s.

Principal sequence pattern analysis of episodes of excess mortality due to heat in the Barcelona metropolitan area.

PubMed

Peña, Juan Carlos; Aran, Montserrat; Raso, José Miguel; Pérez-Zanón, Nuria

2015-04-01

The aim of the study is to classify the synoptic sequences associated with excess mortality during the warm season in the Barcelona metropolitan area. To achieve this purpose, we undertook a principal sequence pattern analysis that incorporates different atmospheric levels, in an attempt at identifying the main features that account for dynamic and thermodynamic atmospheric processes. The sequence length was determined by the short-term displacement between temperature and mortality. To detect this lag, we applied the cross-correlation function to the residuals obtained from the modelling of the daily temperature and mortality series of summer. These residuals were estimated by means of an autoregressive integrated moving average (ARIMA) model. A 7-day sequence emerged as the basic temporal unit for evaluating the synoptic background that triggers the temperature related to excess mortality in the Barcelona metropolitan area. The principal sequence pattern analysis distinguished three main synoptic patterns: two dynamic configurations produced by southern fluxes related to an Atlantic low, which can be associated with heat waves recorded in southern Europe, and a third pattern identified by a stagnation situation associated with the persistence of a blocking anticyclone over Europe, related to heat waves recorded in northern and central western Europe.

Homeostatic and Circadian Abnormalities in Sleep and Arousal in Gulf War Syndrome

DTIC Science & Technology

2013-10-01

temperature, melatonin , vigilance 16. SECURITY CLASSIFICATION OF: U 17. LIMITATION OF ABSTRACT 18. NUMBER OF PAGES 19a. NAME OF RESPONSIBLE PERSON...analysis of slow wave characteristics, origin and propagation. Circadian rhythm is also assessed, including temperature and salivary melatonin ...to note diurnal changes, as well as morning cortisol rise from natural wake. We also have collected melatonin samples in a low light environment to

Planetary wave-gravity wave interactions during mesospheric inversion layer events

NASA Astrophysics Data System (ADS)

Ramesh, K.; Sridharan, S.; Raghunath, K.; Vijaya Bhaskara Rao, S.; Bhavani Kumar, Y.

2013-07-01

lidar temperature observations over Gadanki (13.5°N, 79.2°E) show a few mesospheric inversion layer (MIL) events during 20-25 January 2007. The zonal mean removed SABER temperature shows warm anomalies around 50°E and 275°E indicating the presence of planetary wave of zonal wave number 2. The MIL amplitudes in SABER temperature averaged for 10°N-15°N and 70°E-90°E show a clear 2 day wave modulation during 20-28 January 2007. Prior to 20 January 2007, a strong 2day wave (zonal wave number 2) is observed in the height region of 80-90 km and it gets largely suppressed during 20-26 January 2007 as the condition for vertical propagation is not favorable, though it prevails at lower heights. The 10 day mean zonal wind over Tirunelveli (8.7°N, 77.8°E) shows deceleration of eastward winds indicating the westward drag due to wave dissipation. The nightly mean MF radar observed zonal winds show the presence of alternating eastward and westward winds during the period of 20-26 January 2007. The two dimensional spectrum of Rayleigh lidar temperature observations available for the nights of 20, 22, and 24 January 2007 shows the presence of gravity wave activity with periods 18 min, 38 min, 38 min, and vertical wavelengths 6.4 km, 4.0 km, 6.4 km respectively. From the dispersion relation of gravity waves, it is inferred that these waves are internal gravity waves rather than inertia gravity waves with the horizontal phase speeds of ~40 m/s, ~37 m/s, and ~50 m/s respectively. Assuming the gravity waves are eastward propagating waves, they get absorbed only in the eastward local wind fields of the planetary wave thereby causing turbulence and eddy diffusion which can be inferred from the estimation of large drag force due to the breaking of gravity wave leading to the formation of large amplitude inversion events in alternate nights. The present study shows that, the mesospheric temperature inversion is caused mainly due to the gravity wave breaking and the inversion amplitude may get modulated by the interaction between gravity waves and planetary waves. The eddy diffusion associated with gravity wave drag may also cause suppression in the planetary wave activity.

Laser-induced pressure-wave and barocaloric effect during flash diffusivity measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Hsin; Porter, Wallace D.; Dinwiddie, Ralph Barton

We report laser-induced pressure-wave and barocaloric effect captured by an infrared detector during thermal diffusivity measurements. Very fast (< 1 ms) and negative transients during laser flash measurements were captured by the infrared detector on thin, high thermal conductivity samples. Standard thermal diffusivity analysis only focuses the longer time scale thermal transient measured from the back surface due to thermal conduction. These negative spikes are filtered out and ignored as noise or anomaly from instrument. This study confirmed that the initial negative signal was indeed a temperature drop induced by the laser pulse. The laser pulse induced instantaneous volume expansionmore » and the associated cooling in the specimen can be explained by the barocaloric effect. The initial cooling (< 100 microsecond) is also known as thermoelastic effect in which a negative temperature change is generated when the material is elastically deformed by volume expansion. A subsequent temperature oscillation in the sample was observed and only lasted about one millisecond. The pressure-wave induced thermal signal was systematically studied and analyzed. In conclusion, the underlying physics of photon-mechanical-thermal energy conversions and the potential of using this signal to study barocaloric effects in solids are discussed.« less

Laser-induced pressure-wave and barocaloric effect during flash diffusivity measurements

DOE PAGES

Wang, Hsin; Porter, Wallace D.; Dinwiddie, Ralph Barton

2017-08-01

We report laser-induced pressure-wave and barocaloric effect captured by an infrared detector during thermal diffusivity measurements. Very fast (< 1 ms) and negative transients during laser flash measurements were captured by the infrared detector on thin, high thermal conductivity samples. Standard thermal diffusivity analysis only focuses the longer time scale thermal transient measured from the back surface due to thermal conduction. These negative spikes are filtered out and ignored as noise or anomaly from instrument. This study confirmed that the initial negative signal was indeed a temperature drop induced by the laser pulse. The laser pulse induced instantaneous volume expansionmore » and the associated cooling in the specimen can be explained by the barocaloric effect. The initial cooling (< 100 microsecond) is also known as thermoelastic effect in which a negative temperature change is generated when the material is elastically deformed by volume expansion. A subsequent temperature oscillation in the sample was observed and only lasted about one millisecond. The pressure-wave induced thermal signal was systematically studied and analyzed. In conclusion, the underlying physics of photon-mechanical-thermal energy conversions and the potential of using this signal to study barocaloric effects in solids are discussed.« less

Effect of electron temperature on small-amplitude electron acoustic solitary waves in non-planar geometry

NASA Astrophysics Data System (ADS)

Bansal, Sona; Aggarwal, Munish; Gill, Tarsem Singh

2018-04-01

Effects of electron temperature on the propagation of electron acoustic solitary waves in plasma with stationary ions, cold and superthermal hot electrons is investigated in non-planar geometry employing reductive perturbation method. Modified Korteweg-de Vries equation is derived in the small amplitude approximation limit. The analytical and numerical calculations of the KdV equation reveal that the phase velocity of the electron acoustic waves increases as one goes from planar to non planar geometry. It is shown that the electron temperature ratio changes the width and amplitude of the solitary waves and when electron temperature is not taken into account,our results completely agree with the results of Javidan & Pakzad (2012). It is found that at small values of τ , solitary wave structures behave differently in cylindrical ( {m} = 1), spherical ( {m} = 2) and planar geometry ( {m} = 0) but looks similar at large values of τ . These results may be useful to understand the solitary wave characteristics in laboratory and space environments where the plasma have multiple temperature electrons.

Analysis of moving surface structures at a laser-induced boiling front

NASA Astrophysics Data System (ADS)

Matti, R. S.; Kaplan, A. F. H.

2014-10-01

Recently ultra-high speed imaging enabled to observe moving wave patterns on metal melts that experience laser-induced boiling. In laser materials processing a vertical laser-induced boiling front governs processes like keyhole laser welding, laser remote fusion cutting, laser drilling or laser ablation. The observed waves originate from temperature variations that are closely related to the melt topology. For improved understanding of the essential front mechanisms and of the front topology, for the first time a deeper systematic analysis of the wave patterns was carried out. Seven geometrical shapes of bright or dark domains were distinguished and categorized, in particular bright peaks of three kinds and dark valleys, often inclined. Two categories describe special flow patterns at the top and bottom of the front. Dynamic and statistical analysis has revealed that the shapes often combine or separate from one category to another when streaming down the front. The brightness of wave peaks typically fluctuates during 20-50 μs. This variety of thermal wave observations is interpreted with respect to the accompanying surface topology of the melt and in turn for governing local mechanisms like absorption, shadowing, boiling, ablation pressure and melt acceleration. The findings can be of importance for understanding the key process mechanisms and for optimizing laser materials processing.

Electric dipole radiation at VLF in a uniform warm magneto-plasma.

NASA Technical Reports Server (NTRS)

Wang, T. N. C.; Bell, T. F.

1972-01-01

Use of a linear full electromagnetic wave theory to calculate the input impedance of an electric antenna embedded in a uniform, lossless, unbounded warm magnetoplasma, which is assumed to consist of warm electrons and cold ions. In calculating the dipole radiation resistance for the thermal modes and the thermally modified whistler mode the analysis includes the finite temperature only for the electrons. In deriving the formal solution of the warm plasma dipole input impedance a full-wave analysis is used and two antenna orientations are considered, parallel and perpendicular to the static magnetic field. A general dispersion equation governing the modes of propagation is derived and a detailed analysis is made of the propagation characteristics of these modes.

Numerical Analysis on Thermal Non-Equilibrium Process of Laser-Supported Detonation Wave in Axisymmetric Nozzle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shiraishi, Hiroyuki

Numerical Analyses on Laser-Supported Plasma (LSP) have been performed for researching the mechanism of laser absorption occurring in the laser propulsion system. Above all, Laser-Supported Detonation (LSD), categorized as one type of LSP, is considered as one of the most important phenomena because it can generate high pressure and high temperature for performing highly effective propulsion. For simulating generation and propagation of LSD wave, I have performed thermal non-equilibrium analyses by Navier-stokes equations, using a CO{sub 2} gasdynamic laser into an inert gas, where the most important laser absorption mechanism for LSD propagation is Inverse Bremsstrahlung. As a numerical method,more » TVD scheme taken into account of real gas effects and thermal non-equilibrium effects by using a 2-temperature model, is applied. In this study, I analyze a LSD wave propagating through a conical nozzle, where an inner space of an actual laser propulsion system is simplified.« less

Spin waves and magnetic exchange interactions in insulating Rb(0.89)Fe(1.58)Se(2).

PubMed

Wang, Miaoyin; Fang, Chen; Yao, Dao-Xin; Tan, GuoTai; Harriger, Leland W; Song, Yu; Netherton, Tucker; Zhang, Chenglin; Wang, Meng; Stone, Matthew B; Tian, Wei; Hu, Jiangping; Dai, Pengcheng

2011-12-06

The parent compounds of iron pnictide superconductors are bad metals with a collinear antiferromagnetic structure and Néel temperatures below 220 K. Although alkaline iron selenide A(y)Fe(1.6+x)Se(2) (A=K, Rb, Cs) superconductors are isostructural with iron pnictides, in the vicinity of the undoped limit they are insulators, forming a block antiferromagnetic order and having Néel temperatures of roughly 500 K. Here we show that the spin waves of the insulating antiferromagnet Rb(0.89)Fe(1.58)Se(2) can be accurately described by a local moment Heisenberg Hamiltonian. A fitting analysis of the spin wave spectra reveals that the next-nearest neighbour couplings in Rb(0.89)Fe(1.58)Se(2), (Ba,Ca,Sr)Fe(2)As(2), and Fe(1.05)Te are of similar magnitude. Our results suggest a common origin for the magnetism of all the Fe-based superconductors, despite having different ground states and antiferromagnetic orderings.

Distribution of deuterium and hydrogen in Zr and Ti foil assemblies under the action of a pulsed deuterium high-temperature plasma

NASA Astrophysics Data System (ADS)

Bondarenko, G. G.; Volobuev, I. V.; Eriskin, A. A.; Kobzev, A. P.; Nikulin, V. Ya.; Peregudova, E. N.; Silin, P. V.; Borovitskaya, I. V.

2017-09-01

Deuteron and proton elastic recoil detection analysis is used to study the accumulation and redistribution of deuterium and hydrogen in assemblies of two high-pure zirconium or titanium foils upon pulsed action of high-temperature deuterium plasma (PHTDP) in a plasma-focus installation PF-4. It is noted that, under the action of PHTDP, an implanted deuterium and hydrogen gas impurity are redistributed in the irradiated foils in large depths, which are significantly larger than the deuterium ion free paths (at their maximum velocity to 108 cm/s). The observed phenomenon is attributed to the carrying out of implanted deuterium and hydrogen under the action of powerful shock waves formed in the metallic foils under the action of PHTDP and/or the acceleration of diffusion of deuterium and hydrogen atoms under the action of a compression-rarefaction shock wave at the shock wave front with the redistribution of deuterium and hydrogen to large depths.

Clinical Significance of J Waves in Patients Undergoing Therapeutic Hypothermia for Out-of-Hospital Cardiac Arrest.

PubMed

Harhash, Ahmed; Gussak, Ihor; Cassuto, James; Winters, Stephen L

2017-02-01

Hypothermia is associated with the development of J waves. However, little is known about the impact of these electrocardiogram (ECG) findings on the development of ventricular arrhythmias and patient outcomes during therapeutic hypothermia (TH) postresuscitation from out-of-hospital cardiac arrest (OHCA). We investigated the prevalence of J waves in OHCA patients prior to and during TH. Additionally, we explored the incidence of atrial and ventricular arrhythmias and in-hospital mortality for patients with and without J waves either at baseline, during TH, or both. We conducted a retrospective analysis of patients who suffered OHCA and underwent TH (goal temperature of 32-34°C). Fifty-nine patients were stratified dependent upon the presence of or the development of J waves on surface ECGs. Descriptive analysis and logistic regression modeling were used to assess the population differences and mortality, respectively, between patients who developed J waves during TH and those who did not. There was no difference in the development of in-hospital atrial or ventricular arrhythmias between patients with J waves present during TH (16%) and those without (17.6%, P = 0.834). Compared to patients without J waves at baseline and during TH, those with J waves present both at baseline and during TH had significantly worse survival (hazard ratio = 12.42, P = 0.046). While J waves are common ECG findings during TH in patients resuscitated from OHCA, our study demonstrated an increase in mortality for patients with J waves present both at baseline and during TH. © 2016 Wiley Periodicals, Inc.

In situ laser annealing system for real-time surface kinetic analysis

NASA Astrophysics Data System (ADS)

Wang, Q.; Sun, Y.-M.; Zhao, W.; Campagna, J.; White, J. M.

2002-11-01

For real-time analysis during thermal annealing, a continuous wave CO2 infrared laser was coupled to a surface analysis system equipped for x-ray photoelectron spectroscopy (XPS) and ion scattering spectroscopy (ISS). The laser beam was directed into the vacuum chamber through a ZnSe window to the back side of the sample. With 10 W laser output, the sample temperature reached 563 K. The chamber remained below 10-8 Torr during annealing and allowed XPS and ISS data to be gathered as a function of time at selected temperatures. As a test example, real time Cu2O reduction at 563 K was investigated.

The effect of heat waves, elevated [CO2 ] and low soil water availability on northern red oak (Quercus rubra L.) seedlings.

PubMed

Bauweraerts, Ingvar; Wertin, Timothy M; Ameye, Maarten; McGuire, Mary Anne; Teskey, Robert O; Steppe, Kathy

2013-02-01

The frequency and intensity of heat waves are predicted to increase. This study investigates whether heat waves would have the same impact as a constant increase in temperature with the same heat sum, and whether there would be any interactive effects of elevated [CO2 ] and soil moisture content. We grew Quercus rubra seedlings in treatment chambers maintained at either ambient or elevated [CO2 ] (380 or 700 μmol CO2 mol(-1) ) with temperature treatments of ambient, ambient +3 °C, moderate heat wave (+6 °C every other week) or severe heat wave (+12 °C every fourth week) temperatures. Averaged over a 4-week period, and the entire growing season, the three elevated temperature treatments had the same average temperature and heat sum. Half the seedlings were watered to a soil water content near field capacity, half to about 50% of this value. Foliar gas exchange measurements were performed morning and afternoon (9:00 and 15:00 hours) before, during and after an applied heat wave in August 2010. Biomass accumulation was measured after five heat wave cycles. Under ambient [CO2 ] and well-watered conditions, biomass accumulation was highest in the +3 °C treatment, intermediate in the +6 °C heat wave and lowest in the +12 °C heat wave treatment. This response was mitigated by elevated [CO2 ]. Low soil moisture significantly decreased net photosynthesis (Anet ) and biomass in all [CO2 ] and temperature treatments. The +12 °C heat wave reduced afternoon Anet by 23% in ambient [CO2 ]. Although this reduction was relatively greater under elevated [CO2 ], Anet values during this heat wave were still 34% higher than under ambient [CO2 ]. We concluded that heat waves affected biomass growth differently than the same amount of heat applied uniformly over the growing season, and that the plant response to heat waves also depends on [CO2 ] and soil moisture conditions. © 2012 Blackwell Publishing Ltd.

Minority heating scenarios in ^4He(H) and ^3He(H) SST-1 plasmas

NASA Astrophysics Data System (ADS)

Chattopadhyay, Asim Kumar

2018-01-01

A numerical analysis of ion cyclotron resonance heating scenarios in two species of low ion temperature plasma has been done to elucidate the physics and possibility to achieve H-mode in tokamak plasma. The analysis is done in the steady-state superconducting tokamak, SST-1, using phase-I plasma parameters which is basically L-mode plasma parameters having low ion temperature and magnetic field with the help of the ion cyclotron heating code TORIC combined with `steady state Fokker-Planck quasilinear' (SSFPQL) solver. As a minority species hydrogen has been used in ^3He and ^4He plasmas to make two species ^3He(H) and ^4He(H) plasmas to study the ion cyclotron wave absorption scenarios. The minority heating is predominant in ^3He(H) and ^4He(H) plasmas as minority resonance layers are not shielded by ion-ion resonance and cut-off layers in both cases, and it is better in ^4He(H) plasma due to the smooth penetration of wave through plasma-vacuum surface. In minority concentration up to 15%, it has been observed that minority ion heating is the principal heating mechanism compared to electron heating and heating due to mode conversion phenomena. Numerical analysis with the help of SSFPQL solver shows that the tail of the distribution function of the minority ion is more energetic than that of the majority ion and therefore, more anisotropic. Due to good coupling of the wave and predominance of the minority heating regime, producing energetic ions in the tail region of the distribution function, the ^4He(H) and ^3He(H) plasmas could be studied in-depth to achieve H-mode in two species of low-temperature plasma.

Wave combustors for trans-atmospheric vehicles

NASA Technical Reports Server (NTRS)

Menees, Gene P.; Bowles, Jeffrey V.; Adelman, Henry G.; Cambier, Jean-Luc

1989-01-01

A performance analysis is given of a conceptual transatmospheric vehicle (TAV). The TAV is powered by a an oblique detonation wave engine (ODWE). The ODWE is an airbreathing hypersonic propulsion system which utilizes shock and detonation waves to enhance fuel-air mixing and combustion in supersonic flow. In this wave combustor concept, an oblique shock wave in the combustor can act as a flameholder by increasing the pressure and temperature of the air-fuel mixture, thereby decreasing the ignition delay. If the oblique shock is sufficiently strong, then the combustion front and the shock wave can couple into a detonation wave. In this case, combustion occurs almost instantaneously in a thin zone behind the wave front. The result is a shorter lighter engine compared to the scramjet. The ODWE-powered hypersonic vehicle performance is compared to that of a scramjet-powered vehicle. Among the results outlined, it is found that the ODWE trades a better engine performance above Mach 15 for a lower performance below Mach 15. The overall higher performance of the ODWE results in a 51,000-lb weight savings and a higher payload weight fraction of approximately 12 percent.

Electron acoustic solitary waves in a magnetized plasma with nonthermal electrons and an electron beam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, S. V., E-mail: satyavir@iigs.iigm.res.in; Lakhina, G. S., E-mail: lakhina@iigs.iigm.res.in; University of the Western Cape, Belville

2016-08-15

A theoretical investigation is carried out to study the obliquely propagating electron acoustic solitary waves having nonthermal hot electrons, cold and beam electrons, and ions in a magnetized plasma. We have employed reductive perturbation theory to derive the Korteweg-de-Vries-Zakharov-Kuznetsov (KdV-ZK) equation describing the nonlinear evolution of these waves. The two-dimensional plane wave solution of KdV-ZK equation is analyzed to study the effects of nonthermal and beam electrons on the characteristics of the solitons. Theoretical results predict negative potential solitary structures. We emphasize that the inclusion of finite temperature effects reduces the soliton amplitudes and the width of the solitons increasesmore » by an increase in the obliquity of the wave propagation. The numerical analysis is presented for the parameters corresponding to the observations of “burst a” event by Viking satellite on the auroral field lines.« less

Auroral origin of medium scale gravity waves in neutral composition and temperature

NASA Technical Reports Server (NTRS)

Chandra, S.; Spencer, N. W.; Krankowsky, D.; Laemmerzahl, P.

1979-01-01

The kinetic temperature and neutral composition data obtained from the Aeros B neutral atmosphere temperature experiment and the neutral and ion mass spectrometer show spatial structures characteristic of medium scale gravity waves with a wavelength in the range of several hundred kilometers. These waves are associated with auroral activity, and their spatial structure reflects the time history of the auroral electrojet. The medium scale gravity waves tend to propagate to mid-latitudes on the nightside. On the dayside their range is limited to high latitudes. Gravity waves are carriers of auroral energy to middle and low latitudes where they may cause irreversible changes in temperature via viscous dissipation. Since auroral activity occurs frequently, it is suggested that this energy reaches the mid-latitude region of the thermosphere much more frequently than is indicated by planetary magnetic indices.

Climate Variability and Impact at NASA's Marshal Space Flight Center

NASA Technical Reports Server (NTRS)

Smoot, James L.; Jedlovec, Gary; Williams, Brett

2013-01-01

Climate analysis for the Southeast U. S. has indicated that inland regions have experienced an average temperature increase of 2F since 1970. This trend is generally characterized by warmer winters with an indication of increased precipitation in the Fall season. Extended periods of limited rainfall in the Spring and Summer periods have had greater areal coverage and, at other times the number of precipitation events has been increasing. Climate model projections for the next 10-70 years indicate warmer temperatures for the Southeast U.S., particularly in the Spring and Summer, with some indication of more extremes in temperature and precipitation as shown in the table below. The realization of these types of regional climate changes in the form of extended heat waves and droughts and their subsequent stress on facilities, infrastructure, and workforce could have substantial impact on the activities and functions of NASA's Marshall Space Flight Center (MSFC) in Huntsville, Alabama. This presentation will present the results of an examination of the 100 year temperature and precipitation record for MSFC. Local warming has cause an increase in daily maximum and minimum temperatures by nearly 3F, with a substantial increase in the number of maximum temperatures exceeding 90F and a decrease in the number of days with minimum temperatures below freezing. These trends have substantial impact of the number of heating / cooling degree days for the area. Yearly precipitation totals are inversely correlated with the change in mean temperature and the frequency of heavy rain events has remain consistent with the changes in yearly totals. An extended heat wave index was developed which shows an increase in frequency of heat waves over the last 35 years and a subsequent reduction in precipitation during the heat waves. This trend will contribute to more intense drought conditions over the northern Alabama region, increasing the potential of destructive wildfires in and around the Center. MSFC has begun using this climate change information to adapt short-term and long-term plans for Center operations.

Physical Mechanism of the Surface Air Temperature Variability in Korea and Near Seven-Day Oscillations

NASA Astrophysics Data System (ADS)

Kim, K.; Roh, J.

2009-12-01

The first three principal modes of wintertime surface temperature variability in Seoul, Korea (126.59°E, 37.33°N) are extracted from the 1979-2008 observed records via cyclostationary EOF (CSEOF) analysis. Then, physically consistent patterns of several key physical variables over East Asia (97.5°-152.5°E×22.5°-72.5°N) are derived from the NCEP/NCAR reanalysis data in order to understand the physical and dynamical mechanisms of the derived CSEOF modes. The first mode represents the seasonal cycle, the principle physical mechanism of which is associated with the continent/ocean sea level pressure contrast. The second mode mainly describes overall wintertime warming or cooling. The third mode depicts subseasonal fluctuations of surface temperature. Sea level pressure anomalies to the west of Korea (eastern China) and those with an opposite sign to the east of Korea (Japan) are a major physical mechanism both for the second mode and the third mode. These sea level pressure anomalies with opposite signs alter the amount of warm air to the south of Korea, which, in turn, varies the surface temperature in Korea. The PC time series of the seasonal cycle is significantly correlated with the East Asian winter monsoon index and exhibits a conspicuous downward trend. The PC time series of the second mode exhibits a positive trend. These trends imply that the wintertime surface temperature in Korea has increased and the seasonal cycle has weakened gradually in the past 30 years; the sign of greenhouse warming is clear in both PC time series. The seasonal cycle has decreased since the impact of warming as reflected in the sea level pressure change is much stronger over the continent than over the ocean; greater sea level pressure decrease over the continent than over the ocean reduces the wintertime sea level pressure contrast between the continent and the ocean thereby weakening the seasonal cycle. The ~7-day oscillations, also called the three-cold-day/four-warm-day events, are clearly seen in the second and the third CSEOF modes. The ~7-day oscillations are a major component of high-frequency variability in much of the analysis domain and are a manifestation of Rossby waves. Rossby waves aloft result in the concerted variation of physical variables in the atmospheric column; the nature of this response is of nearly barotropic and is clearly felt at the surface. Due to the stronger mean zonal wind, the disturbances by Rossby waves propagate eastward at ~8-12 m/sec; the passing of Rossby waves with alternating signs produces the ~7-day temperature oscillations in Korea. Thus, it is the speed of eastward propagation of Rossby waves not the phase speed of Rossby waves that determines the period of oscillations.

Oblique ion-acoustic cnoidal waves in two temperature superthermal electrons magnetized plasma

NASA Astrophysics Data System (ADS)

Panwar, A.; Ryu, C. M.; Bains, A. S.

2014-12-01

A study is presented for the oblique propagation of ion acoustic cnoidal waves in a magnetized plasma consisting of cold ions and two temperature superthermal electrons modelled by kappa-type distributions. Using the reductive perturbation method, the nonlinear Korteweg de-Vries equation is derived, which further gives the solutions with a special type of cnoidal elliptical functions. Both compressive and rarefactive structures are found for these cnoidal waves. Nonlinear periodic cnoidal waves are explained in terms of plasma parameters depicting the Sagdeev potential and the phase curves. It is found that the density ratio of hot electrons to ions μ significantly modifies compressive/refractive wave structures. Furthermore, the combined effects of superthermality of cold and hot electrons κ c , κ h , cold to hot electron temperature ratio σ, angle of propagation and ion cyclotron frequency ωci have been studied in detail to analyze the height and width of compressive/refractive cnoidal waves. The findings in the present study could have important implications in understanding the physics of electrostatic wave structures in the Saturn's magnetosphere where two temperature superthermal electrons are present.

A Gaussian wave packet phase-space representation of quantum canonical statistics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coughtrie, David J.; Tew, David P.

2015-07-28

We present a mapping of quantum canonical statistical averages onto a phase-space average over thawed Gaussian wave-packet (GWP) parameters, which is exact for harmonic systems at all temperatures. The mapping invokes an effective potential surface, experienced by the wave packets, and a temperature-dependent phase-space integrand, to correctly transition from the GWP average at low temperature to classical statistics at high temperature. Numerical tests on weakly and strongly anharmonic model systems demonstrate that thermal averages of the system energy and geometric properties are accurate to within 1% of the exact quantum values at all temperatures.

Heat waves according to warm spell duration index in Slovakia during 1901-2016

NASA Astrophysics Data System (ADS)

Bochníček, Oliver; Faško, Pavel; Markovič, Ladislav

2017-04-01

A heat wave is a prolonged period of extremely high temperatures for a particular region. However, there exist no universal definitions for a heat wave as it is relative to a specific area and to a certain time of year. In fact, average temperatures in one region may be considered heat wave conditions in another. For instance, an average day in the Mediterranean would be regarded as heat wave conditions in Northern Europe. We have known that World Meteorological Organization definition of a heatwave which is "when the daily maximum temperature of more than five consecutive days exceeds the average maximum temperature by 5 °C, the normal period being 1961-1990". This rule has been accepted in contribution Heat waves and warm periods in Slovakia (Oliver Bochníček - Pavol Fa\\vsko - Ladislav Markovič) published (presented) in EGU 2016. To move on we have tried another criterion for heat waves evaluation (according to warm spell duration index, WSDI) and period since 1901 (1951) to 2016. Important for many sectors (hydrology, agriculture, transportation and tourism) is, that heat waves have been expected during the whole year and period, that is why it can have various impacts. Heat waves occurrence gave us interesting results especially after the 1990.

Temperature effects in ultrasonic Lamb wave structural health monitoring systems.

PubMed

Lanza di Scalea, Francesco; Salamone, Salvatore

2008-07-01

There is a need to better understand the effect of temperature changes on the response of ultrasonic guided-wave pitch-catch systems used for structural health monitoring. A model is proposed to account for all relevant temperature-dependent parameters of a pitch-catch system on an isotropic plate, including the actuator-plate and plate-sensor interactions through shear-lag behavior, the piezoelectric and dielectric permittivity properties of the transducers, and the Lamb wave dispersion properties of the substrate plate. The model is used to predict the S(0) and A(0) response spectra in aluminum plates for the temperature range of -40-+60 degrees C, which accounts for normal aircraft operations. The transducers examined are monolithic PZT-5A [PZT denotes Pb(Zr-Ti)O3] patches and flexible macrofiber composite type P1 patches. The study shows substantial changes in Lamb wave amplitude response caused solely by temperature excursions. It is also shown that, for the transducers considered, the response amplitude changes follow two opposite trends below and above ambient temperature (20 degrees C), respectively. These results can provide a basis for the compensation of temperature effects in guided-wave damage detection systems.

INSTABILITIES DRIVEN BY THE DRIFT AND TEMPERATURE ANISOTROPY OF ALPHA PARTICLES IN THE SOLAR WIND

DOE Office of Scientific and Technical Information (OSTI.GOV)

Verscharen, Daniel; Bourouaine, Sofiane; Chandran, Benjamin D. G., E-mail: daniel.verscharen@unh.edu, E-mail: s.bourouaine@unh.edu, E-mail: benjamin.chandran@unh.edu

2013-08-20

We investigate the conditions under which parallel-propagating Alfven/ion-cyclotron (A/IC) waves and fast-magnetosonic/whistler (FM/W) waves are driven unstable by the differential flow and temperature anisotropy of alpha particles in the solar wind. We focus on the limit in which w{sub Parallel-To {alpha}} {approx}> 0.25v{sub A}, where w{sub Parallel-To {alpha}} is the parallel alpha-particle thermal speed and v{sub A} is the Alfven speed. We derive analytic expressions for the instability thresholds of these waves, which show, e.g., how the minimum unstable alpha-particle beam speed depends upon w{sub Parallel-To {alpha}}/v{sub A}, the degree of alpha-particle temperature anisotropy, and the alpha-to-proton temperature ratio. Wemore » validate our analytical results using numerical solutions to the full hot-plasma dispersion relation. Consistent with previous work, we find that temperature anisotropy allows A/IC waves and FM/W waves to become unstable at significantly lower values of the alpha-particle beam speed U{sub {alpha}} than in the isotropic-temperature case. Likewise, differential flow lowers the minimum temperature anisotropy needed to excite A/IC or FM/W waves relative to the case in which U{sub {alpha}} = 0. We discuss the relevance of our results to alpha particles in the solar wind near 1 AU.« less

Prediction of Skin Temperature Distribution in Cosmetic Laser Surgery

NASA Astrophysics Data System (ADS)

Ting, Kuen; Chen, Kuen-Tasnn; Cheng, Shih-Feng; Lin, Wen-Shiung; Chang, Cheng-Ren

2008-01-01

The use of lasers in cosmetic surgery has increased dramatically in the past decade. To achieve minimal damage to tissues, the study of the temperature distribution of skin in laser irradiation is very important. The phenomenon of the thermal wave effect is significant due to the highly focused light energy of lasers in very a short time period. The conventional Pennes equation does not take the thermal wave effect into account, which the thermal relaxation time (τ) is neglected, so it is not sufficient to solve instantaneous heating and cooling problem. The purpose of this study is to solve the thermal wave equation to determine the realistic temperature distribution during laser surgery. The analytic solutions of the thermal wave equation are compared with those of the Pennes equation. Moreover, comparisons are made between the results of the above equations and the results of temperature measurement using an infrared thermal image instrument. The thermal wave equation could likely to predict the skin temperature distribution in cosmetic laser surgery.

The dynamic process and microscopic mechanism of extraordinary terahertz transmission through perforated superconducting films

PubMed Central

Wu, J. B.; Zhang, X.; Jin, B. B.; Liu, H. T.; Chen, Y. H.; Li, Z. Y.; Zhang, C. H.; Kang, L.; Xu, W. W.; Chen, J.; Wang, H. B.; Tonouchi, M.; Wu, P. H.

2015-01-01

Superconductor is a compelling plasmonic medium at terahertz frequencies owing to its intrinsic low Ohmic loss and good tuning property. However, the microscopic physics of the interaction between terahertz wave and superconducting plasmonic structures is still unknown. In this paper, we conducted experiments of the enhanced terahertz transmission through a series of superconducting NbN subwavelength hole arrays, and employed microscopic hybrid wave model in theoretical analysis of the role of hybrid waves in the enhanced transmission. The theoretical calculation provided a good match of experimental data. In particular, we obtained the following results. When the width of the holes is far below wavelength, the enhanced transmission is mainly caused by localized resonance around individual holes. On the contrary, when the holes are large, hybrid waves scattered by the array of holes dominate the extraordinary transmission. The surface plasmon polaritions are proved to be launched on the surface of superconducting film and the excitation efficiency increases when the temperature approaches critical temperature and the working frequency goes near energy gap frequency. This work will enrich our knowledge on the microscopic physics of extraordinary optical transmission at terahertz frequencies and contribute to developing terahertz plasmonic devices. PMID:26498994

Modeling deflagration waves out of hot spots

NASA Astrophysics Data System (ADS)

Partom, Yehuda

2017-01-01

It is widely accepted that shock initiation and detonation of heterogeneous explosives comes about by a two-step process known as ignition and growth. In the first step a shock sweeping through an explosive cell (control volume) creates hot spots that become ignition sites. In the second step, deflagration waves (or burn waves) propagate out of those hot spots and transform the reactant in the cell into reaction products. The macroscopic (or average) reaction rate of the reactant in the cell depends on the speed of those deflagration waves and on the average distance between neighboring hot spots. Here we simulate the propagation of deflagration waves out of hot spots on the mesoscale in axial symmetry using a 2D hydrocode, to which we add heat conduction and bulk reaction. The propagation speed of the deflagration waves may depend on both pressure and temperature. It depends on pressure for quasistatic loading near ambient temperature, and on temperature at high temperatures resulting from shock loading. From the simulation we obtain deflagration fronts emanating out of the hot spots. For 8 to 13 GPa shocks, the emanating fronts propagate as deflagration waves to consume the explosive between hot spots. For higher shock levels deflagration waves may interact with the sweeping shock to become detonation waves on the mesoscale. From the simulation results we extract average deflagration wave speeds.

Temperature maxima in stable two-dimensional shock waves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kum, O.; Hoover, W.G.; Hoover, C.G.

1997-07-01

We use molecular dynamics to study the structure of moderately strong shock waves in dense two-dimensional fluids, using Lucy{close_quote}s pair potential. The stationary profiles show relatively broad temperature maxima, for both the longitudinal and the average kinetic temperatures, just as does Mott-Smith{close_quote}s model for strong shock waves in dilute three-dimensional gases. {copyright} {ital 1997} {ital The American Physical Society}

Shock-induced thermal wave propagation and response analysis of a viscoelastic thin plate under transient heating loads

NASA Astrophysics Data System (ADS)

Li, Chenlin; Guo, Huili; Tian, Xiaogeng

2018-04-01

This paper is devoted to the thermal shock analysis for viscoelastic materials under transient heating loads. The governing coupled equations with time-delay parameter and nonlocal scale parameter are derived based on the generalized thermo-viscoelasticity theory. The problem of a thin plate composed of viscoelastic material, subjected to a sudden temperature rise at the boundary plane, is solved by employing Laplace transformation techniques. The transient responses, i.e. temperature, displacement, stresses, heat flux as well as strain, are obtained and discussed. The effects of time-delay and nonlocal scale parameter on the transient responses are analyzed and discussed. It can be observed that: the propagation of thermal wave is dynamically smoothed and changed with the variation of time-delay; while the displacement, strain, and stress can be rapidly reduced by nonlocal scale parameter, which can be viewed as an important indicator for predicting the stiffness softening behavior for viscoelastic materials.

In-situ changes in the elastic wave velocity of rock with increasing temperature using high-resolution coda wave interferometry

NASA Astrophysics Data System (ADS)

Griffiths, Luke; Heap, Michael; Lengliné, Olivier; Schmittbuhl, Jean; Baud, Patrick

2017-04-01

Rock undergoes fluctuations in temperature in various settings in Earth's crust, including areas of volcanic or geothermal activity, or industrial environments such as hydrocarbon or geothermal reservoirs. Changes in temperature can cause thermal stresses that can result in the formation of microcracks, which affect the mechanical, physical, and transport properties of rocks. Of the affected physical properties, the elastic wave velocity of rock is particularly sensitive to microcracking. Monitoring the evolution of elastic wave velocity during the thermal stressing of rock therefore provides valuable insight into thermal cracking processes. One monitoring technique is Coda Wave Interferometry (CWI), which infers high-resolution changes in the medium from changes in multiple-scattered elastic waves. We have designed a new experimental setup to perform CWI whilst cyclically heating and cooling samples of granite (cylinders of 20 mm diameter and 40 mm length). In our setup, the samples are held between two pistons within a tube furnace and are heated and cooled at a rate of 1 °C/min to temperatures of up to 300 °C. Two high temperature piezo-transducers are each in contact with an opposing face of the rock sample. The servo-controlled uniaxial press compensates for the thermal expansion and contraction of the pistons and the sample, keeping the coupling between the transducers and the sample, and the axial force acting on the sample, constant throughout. Our setup is designed for simultaneous acoustic emission monitoring (AE is commonly used as a proxy for microcracking), and so we can follow thermal microcracking precisely by combining the AE and CWI techniques. We find that during the first heating/cooling cycle, the onset of thermal microcracking occurs at a relatively low temperature of around 65 °C. The CWI shows that elastic wave velocity decreases with increasing temperature and increases during cooling. Upon cooling, back to room temperature, there is an irreversible relative decrease in velocity of several percent associated with the presence of new thermal microcracks. Our data suggest that few new microcracks were formed when the same sample was subject to subsequent identical heating/cooling cycles as changes in the elastic wave velocity are near-reversible. Our results shed light on the temperature conditions required for thermal microcracking and the influence of temperature on elastic wave velocity with applications to a wide variety of geoscientific disciplines.

Altitude profiles of temperature from 4 to 80 km over the tropics from MST radar and lidar

NASA Astrophysics Data System (ADS)

Parameswaran, K.; Sasi, M. N.; Ramkumar, G.; Nair, P. R.; Deepa, V.; Murthy, B. V. K.; Nayar, S. R. P.; Revathy, K.; Mrudula, G.; Satheesan, K.; Bhavanikumar, Y.; Sivakumar, V.; Raghunath, K.; Rajendraprasad, T.; Krishnaiah, M.

2000-10-01

Using ground-based techniques of MST radar and Lidar, temperature profiles in the entire height range of 4 to 75km are obtained for the first time at a tropical location. The temporal resolution of the profiles is ~1h in the lower altitudes and 12.5min in the higher altitudes and altitude resolution is ~300m. The errors involved in the derived values are presented. Preliminary analysis of temperature variations in a night revealed fluctuations with characteristics resembling those of large-scale gravity waves.

Propagating elastic vibrations dominate thermal conduction in amorphous silicon

NASA Astrophysics Data System (ADS)

Moon, Jaeyun; Latour, Benoit; Minnich, Austin J.

2018-01-01

The thermal atomic vibrations of amorphous solids can be distinguished by whether they propagate as elastic waves or do not propagate due to lack of atomic periodicity. In a -Si, prior works concluded that nonpropagating waves are the dominant contributors to heat transport, with propagating waves being restricted to frequencies less than a few THz and scattered by anharmonicity. Here, we present a lattice and molecular dynamics analysis of vibrations in a -Si that supports a qualitatively different picture in which propagating elastic waves dominate the thermal conduction and are scattered by local fluctuations of elastic modulus rather than anharmonicity. We explicitly demonstrate the propagating nature of waves up to around 10 THz, and further show that pseudoperiodic structures with homogeneous elastic properties exhibit a marked temperature dependence characteristic of anharmonic interactions. Our work suggests that most heat is carried by propagating elastic waves in a -Si and demonstrates that manipulating local elastic modulus variations is a promising route to realize amorphous materials with extreme thermal properties.

Heat waves in lowland Germany and their circulation-related conditions

NASA Astrophysics Data System (ADS)

Tomczyk, Arkadiusz M.; Sulikowska, Agnieszka

2017-09-01

The research study aimed at assessing multiannual variability of heat wave occurrence in the lowland part of Germany between 1966 and 2015 and determining the role of atmospheric circulation in their occurrence. The analysis was conducted with the use of two independent datasets, that is, the dataset of Germany's National Meteorological Service, Deutscher Wetterdienst, and American meteorological reanalysis database of the National Centre for Environmental Prediction/National Centre for Atmospheric Research. This article defines a hot day as a day with maximum temperature of >30 °C, and a heat wave as a sequence of at least three such days. The observed warming translated into an increase in a number of hot days and, consequently, an increase in the frequency of heat wave occurrence. In the analysed 50-year period, the smallest number of heat waves was observed between 1976 and 1985, and the largest number between 2006 and 2015 in the lowland part of Germany. The occurrence of heat waves in lowland Germany was related to anticyclonic circulation.

Fourier Transform Ultrasound Spectroscopy for the determination of wave propagation parameters.

PubMed

Pal, Barnana

2017-01-01

The reported results for ultrasonic wave attenuation constant (α) in pure water show noticeable inconsistency in magnitude. A "Propagating-Wave" model analysis of the most popular pulse-echo technique indicates that this is a consequence of the inherent wave propagation characteristics in a bounded medium. In the present work Fourier Transform Ultrasound Spectroscopy (FTUS) is adopted to determine ultrasonic wave propagation parameters, the wave number (k) and attenuation constant (α) at 1MHz frequency in tri-distilled water at room temperature (25°C). Pulse-echo signals obtained under same experimental conditions regarding the exciting input signal and reflecting boundary wall of the water container for various lengths of water columns are captured. The Fast Fourier Transform (FFT) components of the echo signals are taken to compute k, α and r, the reflection constant at the boundary, using Oak Ridge and Oxford method. The results are compared with existing literature values. Copyright © 2016 Elsevier B.V. All rights reserved.

Color temperature's impact on task performance and brainwaves of school-age children.

PubMed

Park, YunHee

2015-10-01

[Purpose] This study investigated color temperature's impact on task performance. It presents a scientific analysis of brainwave and task performance time changes, and the results of a self-report type survey. [Subjects] Twenty-four elementary school fifth-grade boys and girls with no visual problems participated in the experiment. [Methods] Physiological reaction times of task performance were measured in a laboratory that could fix and maintain color temperature. Brainwave changes and the task performance times were measured, and a self-report questionnaire was conducted in order to measure of emotional reactions. [Results] Regarding the brainwave changes associated with color temperature, alpha waves were emitted in the O2 area when puzzle tasks were illuminated by orange light and low and high beta waves were emitted in the F3 area under white light. Five items (Brilliant, Soft, Lively, Relaxed, Open) were reported predominantly in responses to orange light in the self-report questionnaire. [Conclusion] The results of this study show that relaxation and stability are not assured when the color temperature is low, and that concentration and cognitive activity are not necessarily easier when the color temperature is high. The color temperature change when performing tasks promoted emotional factors more than brainwave, a biological change.

A parametric study of the linear growth of magnetospheric EMIC waves in a hot plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Qi; Cao, Xing; Gu, Xudong, E-mail: guxudong@whu.edu.cn, E-mail: bbni@whu.edu.cn

2016-06-15

Since electromagnetic ion cyclotron (EMIC) waves in the terrestrial magnetosphere play a crucial role in the dynamic losses of relativistic electrons and energetic protons and in the ion heating, it is important to pursue a comprehensive understanding of the EMIC wave dispersion relation under realistic circumstances, which can shed significant light on the generation, amplification, and propagation of magnetospheric EMIC waves. The full kinetic linear dispersion relation is implemented in the present study to evaluate the linear growth of EMIC waves in a multi-ion (H{sup +}, He{sup +}, and O{sup +}) magnetospheric plasma that also consists of hot ring currentmore » protons. Introduction of anisotropic hot protons strongly modifies the EMIC wave dispersion surface and can result in the simultaneous growth of H{sup +}-, He{sup +}-, and O{sup +}-band EMIC emissions. Our parametric analysis demonstrates that an increase in the hot proton concentration can produce the generation of H{sup +}- and He{sup +}-band EMIC waves with higher possibility. While the excitation of H{sup +}-band emissions requires relatively larger temperature anisotropy of hot protons, He{sup +}-band emissions are more likely to be triggered in the plasmasphere or plasmaspheric plume where the background plasma is denser. In addition, the generation of He{sup +}-band waves is more sensitive to the variation of proton temperature than H{sup +}-band waves. Increase of cold heavy ion (He{sup +} and O{sup +}) density increases the H{sup +} cutoff frequency and therefore widens the frequency coverage of the stop band above the He{sup +} gyrofrequency, leading to a significant damping of H{sup +}-band EMIC waves. In contrast, O{sup +}-band EMIC waves characteristically exhibit the temporal growth much weaker than the other two bands, regardless of all considered variables, suggesting that O{sup +}-band emissions occur at a rate much lower than H{sup +}- and He{sup +}-band emissions, which is consistent with the observations.« less

Intermittent gravity-driven flow of grains through narrow pipes

NASA Astrophysics Data System (ADS)

Alvarez, Carlos A.; de Moraes Franklin, Erick

2017-01-01

Grain flows through pipes are frequently found in various settings, such as in pharmaceutical, chemical, petroleum, mining and food industries. In the case of size-constrained gravitational flows, density waves consisting of alternating high- and low-compactness regions may appear. This study investigates experimentally the dynamics of density waves that appear in gravitational flows of fine grains through vertical and slightly inclined pipes. The experimental device consisted of a transparent glass pipe through which different populations of glass spheres flowed driven by gravity. Our experiments were performed under controlled ambient temperature and relative humidity, and the granular flow was filmed with a high-speed camera. Experimental results concerning the length scales and celerities of density waves are presented, together with a one-dimensional model and a linear stability analysis. The analysis exhibits the presence of a long-wavelength instability, with the most unstable mode and a cut-off wavenumber whose values are in agreement with the experimental results.

Waves in magnetized quark matter

NASA Astrophysics Data System (ADS)

Fogaça, D. A.; Sanches, S. M.; Navarra, F. S.

2018-05-01

We study wave propagation in a non-relativistic cold quark-gluon plasma immersed in a constant magnetic field. Starting from the Euler equation we derive linear wave equations and investigate their stability and causality. We use a generic form for the equation of state, the EOS derived from the MIT bag model and also a variant of the this model which includes gluon degrees of freedom. The results of this analysis may be relevant for perturbations propagating through the quark matter phase in the core of compact stars and also for perturbations propagating in the low temperature quark-gluon plasma formed in low energy heavy ion collisions, to be carried out at FAIR and NICA.

Whistler Waves Driven by Anisotropic Strahl Velocity Distributions: Cluster Observations

NASA Technical Reports Server (NTRS)

Vinas, A.F.; Gurgiolo, C.; Nieves-Chinchilla, T.; Gary, S. P.; Goldstein, M. L.

2010-01-01

Observed properties of the strahl using high resolution 3D electron velocity distribution data obtained from the Cluster/PEACE experiment are used to investigate its linear stability. An automated method to isolate the strahl is used to allow its moments to be computed independent of the solar wind core+halo. Results show that the strahl can have a high temperature anisotropy (T(perpindicular)/T(parallell) approximately > 2). This anisotropy is shown to be an important free energy source for the excitation of high frequency whistler waves. The analysis suggests that the resultant whistler waves are strong enough to regulate the electron velocity distributions in the solar wind through pitch-angle scattering

Influence of vertically and obliquely propagating gravity waves on the polar summer mesosphere

NASA Astrophysics Data System (ADS)

Thurairajah, B.; Siskind, D. E.; Bailey, S. M.

2017-12-01

Polar Mesospheric Clouds (PMCs) are sensitive to changes in temperature of the cold polar summer mesosphere, which in turn are modulated by gravity waves (GWs). In this study we investigate the link between PMCs and GWs that propagate both vertically (i.e. wave propagation is directly above the source region) and obliquely (lateral or non-vertical propagation upward but away from the source region). Several observational studies have analyzed the link between PMCs and vertically propagating GWs and have reported both positive and negative correlations. Moreover, while modelling studies have noted the possibility of oblique propagation of GWs from the low-latitude stratosphere to the high-latitude mesosphere, observational studies of the influence of these waves on the polar summer mesosphere are sparse. We present a comprehensive analysis of the influence of vertically and obliquely propagating GWs on the northern hemisphere (NH) polar summer mesosphere using data from 8 PMC seasons. Temperature data from the SOFIE experiment on the AIM satellite and SABER instrument on the TIMED satellite are used to derive GW parameters. SOFIE PMC data in terms of Ice Water Content (IWC) are used to quantify the changes in the polar summer mesosphere. At high latitudes, preliminary analysis of vertically propagating waves indicate a weak but positive correlation between GWs at 50 km and GWs at the PMC altitude of 84 km. Overall there is a negative correlation between GWs at 50 km and IWC and a positive correlation between GWs at 84 km and IWC. These results and the presence of a slanted structure (slanted from the low-latitude stratosphere to the high-latitude mesosphere) in GW momentum flux suggest the possibility of a significant influence of obliquely propagating GWs on the polar summer mesosphere

Kelvin waves: a comparison study between SABER and normal mode analysis of ECMWF data

NASA Astrophysics Data System (ADS)

Blaauw, Marten; Garcia, Rolando; Zagar, Nedjeljka; Tribbia, Joe

2014-05-01

Equatorial Kelvin waves spectra are sensitive to the multi-scale variability of their source of tropical convective forcing. Moreover, Kelvin wave spectra are modified upward by changes in the background winds and stability. Recent high resolution data from observations as well as analyses are capable of resolving the slower Kelvin waves with shorter vertical wavelength near the tropical tropopause. In this presentation, results from a quantitive comparison study of stratospheric Kelvin waves in satellite data (SABER) and analysis data from the ECMWF operational archive will be shown. Temperature data from SABER is extracted over a six year period (2007-2012) with an effective vertical resolution of 2 km. Spectral power of stratospheric Kelvin waves in SABER data is isolated by selecting symmetric and eastward spectral components in the 8-20 days range. Global data from ECMWF operational analysis is extracted for the same six years on 91 model levels (top level at 0.01 hPa) and 25 km horizontal resolution. Using three-dimensional orthogonal normal-mode expansions, the input mass and wind data from ECMWF is projected onto balanced rotational modes and unbalanced inertia-gravity modes, including spectral data for pure Kelvin waves. The results show good agreement between Kelvin waves in SABER and ECMWF analyses data for: (i) the frequency shift of Kelvin wave variance with height and (ii) vertical wavelengths. Variability with respect to QBO will also be discussed. In a previous study, discrepancies in the upper stratosphere were found to be 60% and are found here to be 10% (8-20 day averaged value), which can be explained by the better stratosphere representation in the 91 model level version of the ECMWF operational model. New discrepancies in Kelvin wave variance are found in the lower stratosphere at 20 km. Averaged spectral power over the 8-20 day range is found to be 35% higher in ECMWF compared to SABER data. We compared results at 20 km with additional satellite data from HIRDLS (1 km eff. resolution) and conclude preliminary that SABER data does not represent the shortest 20 day Kelvin waves as well as HIRDLS and ECMWF operational analysis.

Langmuir Probe Analysis of Maser-Driven Alfven Waves Using New LaB6 Cathode in LaPD

NASA Astrophysics Data System (ADS)

Clark, Mary; Dorfman, Seth; Zhu, Ziyan; Rossi, Giovanni; Carter, Troy

2015-11-01

Previous research in the Large Plasma Device shows that specific conditions on the magnetic field and cathode discharge voltage allow an Alfven wave to develop in the cathode-anode region. When the speed of bulk electrons (dependent on discharge voltage) entering the region exceeds the Alfven speed, the electrons can excite a wave. This phenomenon mimics one proposed to exist in the Earth's ionosphere. Previous experiments used a cathode coated with Barium Oxide, and this project uses a new cathode coated with Lanthanum Hexaboride (LaB6). The experiment seeks to characterize the behavior of plasmas generated with the LaB6 source, as well as understand properties of the driven wave when using the new cathode. Langmuir probes are used to find electron temperature, ion saturation current, and plasma density. These parameters determine characteristics of the wave. Preliminary analysis implies that density increases with LaB6 discharge voltage until 170 V, where it levels off. A linear increase in density is expected; the plateau implies cathode power does not ionize the plasma after 170 V. It is possible the power is carried out by the generated Alfven wave, or heats the plasma or cathode. This ``missing'' power is currently under investigation. Work funded by DOE and NSF.

The Effect of Breaking Waves on CO_2 Air-Sea Fluxes in the Coastal Zone

NASA Astrophysics Data System (ADS)

Gutiérrez-Loza, Lucía; Ocampo-Torres, Francisco J.; García-Nava, Héctor

2018-03-01

The influence of wave-associated parameters controlling turbulent CO_2 fluxes through the air-sea interface is investigated in a coastal region. A full year of high-quality data of direct estimates of air-sea CO_2 fluxes based on eddy-covariance measurements is presented. The study area located in Todos Santos Bay, Baja California, Mexico, is a net sink of CO_2 with a mean flux of -1.3 μmol m^{-2}s^{-1} (-41.6 mol m^{-2}yr^{-1} ). The results of a quantile-regression analysis computed between the CO_2 flux and, (1) wind speed, (2) significant wave height, (3) wave steepness, and (4) water temperature, suggest that the significant wave height is the most correlated parameter with the magnitude of the flux but the behaviour of the relation varies along the probability distribution function, with the slopes of the regression lines presenting both positive and negative values. These results imply that the presence of surface waves in coastal areas is the key factor that promotes the increase of the flux from and into the ocean. Further analysis suggests that the local characteristics of the aqueous and atmospheric layers might determine the direction of the flux.

Ultrasonic liquid-level detector for varying temperature and pressure environments

DOEpatents

Anderson, R.L.; Miller, G.N.

1981-10-26

An ultrasonic liquid level detector for use in varying temperature and pressure environments, such as a pressurized water nuclear reactor vessel, is provided. The detector employs ultrasonic extensional and torsional waves launched in a multiplexed alternating sequence into a common sensor. The sensor is a rectangular cross section stainless steel rod which extends into the liquid medium whose level is to be detected. The sensor temperature derived from the extensional wave velocity measurements is used to compensate for the temperature dependence of the torsional wave velocity measurements which are also level dependent. The torsional wave velocity measurements of a multiple reflection sensor then provide a measurement of liquid level over a range of several meters with a small uncertainty over a temperature range of 20 to 250/sup 0/C and pressures up to 15 MPa.

Molecular dynamics simulation of shock-wave loading of copper and titanium

NASA Astrophysics Data System (ADS)

Bolesta, A. V.; Fomin, V. M.

2017-10-01

At extreme pressures and temperatures common materials form new dense phases with compacted atomic arrangements. By classical molecular dynamics simulation we observe that FCC copper undergo phase transformation to BCC structure. The transition occurs under shock wave loading at the pressures above 80 GPa and corresponding temperatures above 2000 K. We calculate phase diagram, show that at these pressures and low temperature FCC phase of copper is still stable and discuss the thermodynamic reason for phase transformation at high temperature shock wave regime. Titanium forms new hexagonal phase at high pressure as well. We calculate the structure of shock wave in titanium and observe that shock front splits in three parts: elastic, plastic and phase transformation. The possibility of using a phase transition behind a shock wave with further unloading for designing nanocrystalline materials with a reduced grain size is also shown.

Method of and apparatus for determining deposition-point temperature

DOEpatents

Mansure, A.J.; Spates, J.J.; Martin, S.J.

1998-10-27

Acoustic-wave sensor apparatus and method are disclosed for analyzing a normally liquid petroleum-based composition for monitoring deposition-point temperature. The apparatus includes at least one acoustic-wave device such as SAW, QCM, FPM, TSM or APM type devices in contact with the petroleum-based composition for sensing or detecting the surface temperature at which deposition occurs and/or rate of deposition as a function of temperature by sensing an accompanying change in frequency, phase shift, damping voltage or damping current of an electrical oscillator to a known calibrated condition. The acoustic wave device is actively cooled to monitor the deposition of constituents such as paraffins by determining the point at which solids from the liquid composition begin to form on the acoustic wave device. The acoustic wave device can be heated to melt or boil off the deposits to reset the monitor and the process can be repeated. 5 figs.

Method of and apparatus for determining deposition-point temperature

DOEpatents

Mansure, Arthur J.; Spates, James J.; Martin, Stephen J.

1998-01-01

Acoustic-wave sensor apparatus and method for analyzing a normally liquid petroleum-based composition for monitoring deposition-point temperature. The apparatus includes at least one acoustic-wave device such as SAW, QCM, FPM, TSM or APM type devices in contact with the petroleum-based composition for sensing or detecting the surface temperature at which deposition occurs and/or rate of deposition as a function of temperature by sensing an accompanying change in frequency, phase shift, damping voltage or damping current of an electrical oscillator to a known calibrated condition. The acoustic wave device is actively cooled to monitor the deposition of constituents such as paraffins by determining the point at which solids from the liquid composition begin to form on the acoustic wave device. The acoustic wave device can be heated to melt or boil off the deposits to reset the monitor and the process can be repeated.

Program Helps To Determine Chemical-Reaction Mechanisms

NASA Technical Reports Server (NTRS)

Bittker, D. A.; Radhakrishnan, K.

1995-01-01

General Chemical Kinetics and Sensitivity Analysis (LSENS) computer code developed for use in solving complex, homogeneous, gas-phase, chemical-kinetics problems. Provides for efficient and accurate chemical-kinetics computations and provides for sensitivity analysis for variety of problems, including problems involving honisothermal conditions. Incorporates mathematical models for static system, steady one-dimensional inviscid flow, reaction behind incident shock wave (with boundary-layer correction), and perfectly stirred reactor. Computations of equilibrium properties performed for following assigned states: enthalpy and pressure, temperature and pressure, internal energy and volume, and temperature and volume. Written in FORTRAN 77 with exception of NAMELIST extensions used for input.

The Formation and Early Evolution of a Coronal Mass Ejection and its Associated Shock Wave on 2014 January 8

NASA Astrophysics Data System (ADS)

Wan, Linfeng; Cheng, Xin; Shi, Tong; Su, Wei; Ding, M. D.

2016-08-01

In this paper, we study the formation and early evolution of a limb coronal mass ejection (CME) and its associated shock wave that occurred on 2014 January 8. The extreme ultraviolet (EUV) images provided by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory disclose that the CME first appears as a bubble-like structure. Subsequently, its expansion forms the CME and causes a quasi-circular EUV wave. Interestingly, both the CME and the wave front are clearly visible at all of the AIA EUV passbands. Through a detailed kinematical analysis, it is found that the expansion of the CME undergoes two phases: a first phase with a strong but transient lateral over-expansion followed by a second phase with a self-similar expansion. The temporal evolution of the expansion velocity coincides very well with the variation of the 25-50 keV hard X-ray flux of the associated flare, which indicates that magnetic reconnection most likely plays an important role in driving the expansion. Moreover, we find that, when the velocity of the CME reaches ˜600 km s-1, the EUV wave starts to evolve into a shock wave, which is evidenced by the appearance of a type II radio burst. The shock’s formation height is estimated to be ˜0.2 R sun, which is much lower than the height derived previously. Finally, we also study the thermal properties of the CME and the EUV wave. We find that the plasma in the CME leading front and the wave front has a temperature of ˜2 MK, while that in the CME core region and the flare region has a much higher temperature of ≥8 MK.

Multifluid Theory of Solitons

NASA Astrophysics Data System (ADS)

Verheest, Frank

2008-03-01

After introducing the basic multifluid model equations, this review discusses three different methods to describe nonlinear plasma waves, by giving a rather general overview of the relevant methodology, followed by a specific and recent application. First, reductive perturbation analysis is applicable to waves that are not too strongly nonlinear, if their linear counterparts have an acoustic-like dispersion at low frequencies. It is discussed for electrostatic modes, with a brief application to dusty plasma waves. The typical paradigm for such problems is the well known KdV equation and its siblings. Stationary waves with larger amplitudes can be treated, i.a., via the fluid-dynamic approach pioneered by McKenzie, which focuses on essential insights into the limitations that restrict the range of available solitary electrostatic solutions. As an illustration, novel electrostatic solutions have been found in plasmas with two-temperature electron species that are relevant in understanding certain magnetospheric plasma observations. The older cousin of the large-amplitude technique is the Sagdeev pseudopotential description, to which the newer fluid-dynamic approach is essentially equivalent. Because the Sagdeev analysis has mostly been applied to electrostatic waves, some recent results are given for electromagnetic modes in pair plasmas, to show its versatility.

Derivation of gravity wave intrinsic parameters and vertical wavelength using a single scanning OH(3-1) airglow spectrometer

NASA Astrophysics Data System (ADS)

Wüst, Sabine; Offenwanger, Thomas; Schmidt, Carsten; Bittner, Michael; Jacobi, Christoph; Stober, Gunter; Yee, Jeng-Hwa; Mlynczak, Martin G.; Russell, James M., III

2018-05-01

For the first time, we present an approach to derive zonal, meridional, and vertical wavelengths as well as periods of gravity waves based on only one OH* spectrometer, addressing one vibrational-rotational transition. Knowledge of these parameters is a precondition for the calculation of further information, such as the wave group velocity vector.OH(3-1) spectrometer measurements allow the analysis of gravity wave ground-based periods but spatial information cannot necessarily be deduced. We use a scanning spectrometer and harmonic analysis to derive horizontal wavelengths at the mesopause altitude above Oberpfaffenhofen (48.09° N, 11.28° E), Germany for 22 nights in 2015. Based on the approximation of the dispersion relation for gravity waves of low and medium frequencies and additional horizontal wind information, we calculate vertical wavelengths. The mesopause wind measurements nearest to Oberpfaffenhofen are conducted at Collm (51.30° N, 13.02° E), Germany, ca. 380 km northeast of Oberpfaffenhofen, by a meteor radar.In order to compare our results, vertical temperature profiles of TIMED-SABER (thermosphere ionosphere mesosphere energetics dynamics, sounding of the atmosphere using broadband emission radiometry) overpasses are analysed with respect to the dominating vertical wavelength.

Ion-Scale Wave Properties and Enhanced Ion Heating across the Magnetopause during Kelvin-Helmholtz Instability

NASA Astrophysics Data System (ADS)

Nykyri, K.; Moore, T.; Dimmock, A. P.

2017-12-01

In the Earth's magnetosphere, the magnetotail plasma sheet ions are much hotter than in the shocked solar wind. On the dawn-sector, the cold-component ions are more abundant and hotter by 30-40 percent when compared to the dusk sector. Recent statistical studies of the flank magnetopause and magnetosheath have shown that the level of temperature asymmetry of the magnetosheath is unable to account for this, so additional physical mechanisms must be at play, either at the magnetopause or plasma sheet that contribute to this asymmetry. In this study, we perform a statistical analysis on the ion-scale wave properties in the three main plasma regimes common to flank magnetopause boundary crossings when the boundary is unstable to KHI: hot and tenuous magnetospheric, cold and dense magnetosheath and mixed [Hasegawa 2004 et al., 2004]. These statistics of ion-scale wave properties are compared to observations of fast magnetosonic wave modes that have recently been linked to Kelvin-Helmholtz vortex centered ion heating [Moore et al., 2016]. The statistical analysis shows that during KH events there is enhanced non-adiabatic heating calculated during (temporal) ion scale wave intervals when compared to non-KH events.

A Dynamic Analysis of Hydrodynamic Wave Journal Bearings

NASA Technical Reports Server (NTRS)

Ene, Nicoleta M.; Dimofte, Florin; Keith, Theo G.

2008-01-01

The purpose of this paper is to study the dynamic behavior of a three-wave journal bearing using a transient approach. The transient analysis permits the determination of the rotor behavior after the fractional frequency whirl appears. The journal trajectory is determined by solving a set of nonlinear equations of motion using the Runge-Katta method. The fluid film forces are computed by integrating the transient Reynolds equation at each time step location of the shaft with respect to the bearing. Because of the large values of the rotational speeds, turbulent effects were included in the computations. The influence of the temperature on the viscosity was also considered. Numerical results were compared to experimenta1 results obtained at the NASA Glenn Research Center. Comparisons of the theoretical results with experimental data were found to be in good agreement. The numerical and experimental results showed that the fluid film of a three-wave journal bearing having a diameter of 30 mm, a length of 27 mm, and a wave amplitude ratio greater than 0.15 is stable even at rotational speeds of 60,000 RPM. For lower wave amplitude ratios, the threshold speed at which the fluid film becomes unstable depends on the wave amplitude and on the supply pocket pressure. Even if the fluid film is unstable, the wave bearing maintains the whirl orbit inside the bearing clearance.

Distribution of Localized States from Fine Analysis of Electron Spin Resonance Spectra in Organic Transistors

NASA Astrophysics Data System (ADS)

Matsui, Hiroyuki; Mishchenko, Andrei S.; Hasegawa, Tatsuo

2010-02-01

We developed a novel method for obtaining the distribution of trapped carriers over their degree of localization in organic transistors, based on the fine analysis of electron spin resonance spectra at low enough temperatures where all carriers are localized. To apply the method to pentacene thin-film transistors, we proved through continuous wave saturation experiments that all carriers are localized at below 50 K. We analyzed the spectra at 20 K and found that the major groups of traps comprise localized states having wave functions spanning around 1.5 and 5 molecules and a continuous distribution of states with spatial extent in the range between 6 and 20 molecules.

Distribution of localized states from fine analysis of electron spin resonance spectra in organic transistors.

PubMed

Matsui, Hiroyuki; Mishchenko, Andrei S; Hasegawa, Tatsuo

2010-02-05

We developed a novel method for obtaining the distribution of trapped carriers over their degree of localization in organic transistors, based on the fine analysis of electron spin resonance spectra at low enough temperatures where all carriers are localized. To apply the method to pentacene thin-film transistors, we proved through continuous wave saturation experiments that all carriers are localized at below 50 K. We analyzed the spectra at 20 K and found that the major groups of traps comprise localized states having wave functions spanning around 1.5 and 5 molecules and a continuous distribution of states with spatial extent in the range between 6 and 20 molecules.

Design of a Tunable, Room Temperature, Continuous-Wave Terahertz Source and Detector using Silicon Waveguides

DTIC Science & Technology

2008-01-30

that will use conventional diode- or hotomultiplier-tube-based optical detectors , which are xtremely sensitive . . HEATING AND FREE-CARRIER IMITATIONS...CONTRACT NUMBER IN-HOUSE Design of a tunable, room temperature, continuous-wave terahertz source and detector using silicon waveguides 5b. GRANT...B 261Design of a tunable, room temperature, continuous-wave terahertz source and detector using silicon waveguides T. Baehr-Jones,1,* M. Hochberg,1,3

Effect of temperature degeneracy and Landau quantization on drift solitary waves and double layers

NASA Astrophysics Data System (ADS)

Shan, Shaukat Ali; Haque, Q.

2018-01-01

The linear and nonlinear drift ion acoustic waves have been investigated in an inhomogeneous, magnetized, dense degenerate, and quantized magnetic field plasma. The linear drift ion acoustic wave propagation along with the nonlinear structures like double layers and solitary waves has been found to be strongly dependent on the drift speed, magnetic field quantization parameter β, and the temperature degeneracy. The graphical illustrations show that the frequency of linear waves and the amplitude of the solitary waves increase with the increase in temperature degeneracy and Landau quantization effect, while the amplitude of the double layers decreases with the increase in η and T. The relevance of the present study is pointed out in the plasma environment of fast ignition inertial confinement fusion, the white dwarf stars, and short pulsed petawatt laser technology.

High temperature integrated ultrasonic shear and longitudinal wave probes

NASA Astrophysics Data System (ADS)

Ono, Y.; Jen, C.-K.; Kobayashi, M.

2007-02-01

Integrated ultrasonic shear wave probes have been designed and developed using a mode conversion theory for nondestructive testing and characterization at elevated temperatures. The probes consisted of metallic substrates and high temperature piezoelectric thick (>40μm) films through a paint-on method. Shear waves are generated due to mode conversion from longitudinal to shear waves because of reflection inside the substrate having a specific shape. A novel design scheme is proposed to reduce the machining time of substrates and thick film fabrication difficulty. A probe simultaneously generating and receiving both longitudinal and shear waves is also developed and demonstrated. In addition, a shear wave probe using a clad buffer rod consisting of an aluminum core and stainless steel cladding has been developed. All the probes were tested and successfully operated at 150°C.

The southern stratospheric gravity wave hot spot: individual waves and their momentum fluxes measured by COSMIC GPS-RO

NASA Astrophysics Data System (ADS)

Hindley, N. P.; Wright, C. J.; Smith, N. D.; Mitchell, N. J.

2015-07-01

Nearly all general circulation models significantly fail to reproduce the observed behaviour of the southern wintertime polar vortex. It has been suggested that these biases result from an underestimation of gravity wave drag on the atmosphere at latitudes near 60° S, especially around the "hot spot" of intense gravity wave fluxes above the mountainous Southern Andes and Antarctic peninsula. Here, we use Global Positioning System radio occultation (GPS-RO) data from the COSMIC satellite constellation to determine the properties of gravity waves in the hot spot and beyond. We show considerable southward propagation to latitudes near 60° S of waves apparently generated over the southern Andes. We propose that this propagation may account for much of the wave drag missing from the models. Furthermore, there is a long leeward region of increased gravity wave energy that sweeps eastwards from the mountains over the Southern Ocean. Despite its striking nature, the source of this region has historically proved difficult to determine. Our observations suggest that this region includes both waves generated locally and orographic waves advected downwind from the hot spot. We describe and use a new wavelet-based analysis technique for the quantitative identification of individual waves from COSMIC temperature profiles. This analysis reveals different geographical regimes of wave amplitude and short-timescale variability in the wave field over the Southern Ocean. Finally, we use the increased numbers of closely spaced pairs of profiles from the deployment phase of the COSMIC constellation in 2006 to make estimates of gravity wave horizontal wavelengths. We show that, given sufficient observations, GPS-RO can produce physically reasonable estimates of stratospheric gravity wave momentum flux in the hot spot that are consistent with measurements made by other techniques. We discuss our results in the context of previous satellite and modelling studies and explain how they advance our understanding of the nature and origins of waves in the southern stratosphere.

The 60 GHz radiometric local vertical sensor experiment

NASA Technical Reports Server (NTRS)

Grauling, C. H., Jr.

1973-01-01

The experiment concept involves the use of millimeter wave radiation the atmospheric oxygen to provide vertical sensing information to a satellite-borne radiometer. The radiance profile studies require the calculation of ray brightness temperature as a function of tangential altitude and atmosphere model, and the computer program developed for this purpose is discussed. Detailed calculations have been made for a total of 12 atmosphere models, including some showing severe warning conditions. The experiment system analysis investigates the effect of various design choices on system behavior. Calculated temperature profiles are presented for a wide variety of frequencies, bandwidths, and atmosphere models. System performance is determined by the convolution of the brightness temperature and an assumed antenna pattern. A compensation scheme to account for different plateau temperatures is developed and demonstrated. The millimeter wave components developed for the local vertical sensor are discussed, with emphasis on the antenna, low noise mixer, and solid state local oscillator. It was concluded that a viable sensing technique exists, useful over a wide range of altitude with an accuracy generally on the order of 0.01 degree or better.

Observed formation of easterly waves over northeast Africa

NASA Astrophysics Data System (ADS)

Jury, Mark R.

2018-06-01

This study explores the thermodynamic and kinematic features of easterly waves over northeast Africa in July-September season 2005-2015. A daily African easterly wave (AEW) index is formulated from transient satellite rainfall and reanalysis vorticity, and the ten most intense cases are studied by composite analysis. Surface moisture is advected from central Africa towards the Red Sea during AEW formation. The anomalous 600 hPa wind circulation is comprized of a cyclonic-south anticyclonic-north rotor pair and accentuated easterly jet along 17N. Composite convection is initiated over Ethiopia and subsequently intensifies following interaction with a zonal circulation located downstream. Composite AEW temperature anomalies reveal a cool lower-warm upper layer heating profile. 2-8 day variance of satellite OLR reaches a maximum over the southern Arabian Peninsula, suggesting an upstream role for surface heating and the Somali Jet. The large scale environment is analyzed by regression of the AEW index onto daily fields of rainfall, surface air pressure and temperature in July-September season ( N = 1004). The rainfall regression reflects a westward propagating AEW wave-train of higher values on 13N and lower values on 7N with a longitude spacing of 25°. The air pressure and temperature regression features a N-S dipole indicating an anomalous northward ITCZ. A low pressure signal west of the Maritime Continent coupled with a warm zone across the South Indian Ocean coincides with AEW formation over the eastern Sahel.

Co-seismic response of water level in the Jingle well (China) associated with the Gorkha Nepal (Mw 7.8) earthquake

NASA Astrophysics Data System (ADS)

He, Anhua; Fan, Xuefang; Zhao, Gang; Liu, Yang; Singh, Ramesh P.; Hu, Yuliang

2017-09-01

Changes in co-seismic water levels associated with the Gorkha Nepal earthquake (25 April 2015, Mw 7.8) were recorded in the Jingle well in Shanxi Province China (longitude E112.03°, latitude N38.35°, about 2769 km from epicenter). Based on the observed water levels, we clearly identified signals relating to P, S and surface waves. However, the water temperature recorded at a depth of 350 m shows no co-seismic changes. A spectrum analysis of co-seismic variations of water level shows that the oscillation frequency and amplitude of water level in the borehole are determined by the natural frequency of the borehole, which is not associated with the propagation of seismic waves. The borehole-aquifer system shows a large amplification associated with ground vibrations generated by earthquakes. Considering the local hydro-geological map and the temperature gradient of the Jingle well, a large volume ;groundwater reservoir; model can be used to explain these processes. Due to seismic wave propagation, the volume of a well-confined aquifer expands and contracts forming fractures that change the water flow. In the well-confined aquifer, water levels oscillate simultaneously with high amplitude ground shaking during earthquakes. However, the water in the center of the ;underground reservoir; remains relatively stationary, without any changes in the water temperature. In addition, a possible precursor wave is recorded in the water level at the Jingle well prior to the Gorkha earthquake.

Wave excitation by nonlinear coupling among shear Alfvén waves in a mirror-confined plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ikezoe, R., E-mail: ikezoe@prc.tsukuba.ac.jp; Ichimura, M.; Okada, T.

2015-09-15

A shear Alfvén wave at slightly below the ion-cyclotron frequency overcomes the ion-cyclotron damping and grows because of the strong anisotropy of the ion temperature in the magnetic mirror configuration, and is called the Alfvén ion-cyclotron (AIC) wave. Density fluctuations caused by the AIC waves and the ion-cyclotron range of frequencies (ICRF) waves used for ion heating have been detected using a reflectometer in a wide radial region of the GAMMA 10 tandem mirror plasma. Various wave-wave couplings are clearly observed in the density fluctuations in the interior of the plasma, but these couplings are not so clear in themore » magnetic fluctuations at the plasma edge when measured using a pick-up coil. A radial dependence of the nonlinearity is found, particularly in waves with the difference frequencies of the AIC waves; bispectral analysis shows that such wave-wave coupling is significant near the core, but is not so evident at the periphery. In contrast, nonlinear coupling with the low-frequency background turbulence is quite distinct at the periphery. Nonlinear coupling associated with the AIC waves may play a significant role in the beta- and anisotropy-limits of a mirror-confined plasma through decay of the ICRF heating power and degradation of the plasma confinement by nonlinearly generated waves.« less

Absolute cavity pyrgeometer

DOEpatents

Reda, Ibrahim

2013-10-29

Implementations of the present disclosure involve an apparatus and method to measure the long-wave irradiance of the atmosphere or long-wave source. The apparatus may involve a thermopile, a concentrator and temperature controller. The incoming long-wave irradiance may be reflected from the concentrator to a thermopile receiver located at the bottom of the concentrator to receive the reflected long-wave irradiance. In addition, the thermopile may be thermally connected to a temperature controller to control the device temperature. Through use of the apparatus, the long-wave irradiance of the atmosphere may be calculated from several measurements provided by the apparatus. In addition, the apparatus may provide an international standard of pyrgeometers' calibration that is traceable back to the International System of Units (SI) rather than to a blackbody atmospheric simulator.

Photothermal waves for two temperature with a semiconducting medium under using a dual-phase-lag model and hydrostatic initial stress

NASA Astrophysics Data System (ADS)

Lotfy, Kh.

2017-07-01

The dual-phase-lag (DPL) model with two different time translations and Lord-Shulman (LS) theory with one relaxation time are applied to study the effect of hydrostatic initial stress on medium under the influence of two temperature parameter(a new model will be introduced using two temperature theory) and photothermal theory. We solved the thermal loading at the free surface in the semi-infinite semiconducting medium-coupled plasma waves with the effect of mechanical force during a photothermal process. The exact expressions of the considered variables are obtained using normal mode analysis also the two temperature coefficient ratios were obtained analytically. Numerical results for the field quantities are given in the physical domain and illustrated graphically under the effects of several parameters. Comparisons are made between the results of the two different models with and without two temperature parameter, and for two different values of the hydrostatic initial stress. A comparison is carried out between the considered variables as calculated from the generalized thermoelasticity based on the DPL model and the LS theory in the absence and presence of the thermoelastic and thermoelectric coupling parameters.

Monitoring of thermal therapy based on shear modulus changes: I. shear wave thermometry.

PubMed

Arnal, Bastien; Pernot, Mathieu; Tanter, Mickael

2011-02-01

The clinical applicability of high-intensity focused ultrasound (HIFU) for noninvasive therapy is today hampered by the lack of robust and real-time monitoring of tissue damage during treatment. The goal of this study is to show that the estimation of local tissue elasticity from shear wave imaging (SWI) can lead to the 2-D mapping of temperature changes during HIFU treatments. This new concept of shear wave thermometry is experimentally implemented here using conventional ultrasonic imaging probes. HIFU treatment and monitoring were, respectively, performed using a confocal setup consisting of a 2.5-MHz single-element transducer focused at 30 mm on ex vivo samples and an 8-MHz ultrasound diagnostic probe. Thermocouple measurements and ultrasound-based thermometry were used as a gold standard technique and were combined with SWI on the same device. The SWI sequences consisted of 2 successive shear waves induced at different lateral positions. Each wave was created using 100-μs pushing beams at 3 depths. The shear wave propagation was acquired at 17,000 frames/s, from which the elasticity map was recovered. HIFU sonications were interleaved with fast imaging acquisitions, allowing a duty cycle of more than 90%. Elasticity and temperature mapping was achieved every 3 s, leading to realtime monitoring of the treatment. Tissue stiffness was found to decrease in the focal zone for temperatures up to 43°C. Ultrasound-based temperature estimation was highly correlated to stiffness variation maps (r² = 0.91 to 0.97). A reversible calibration phase of the changes of elasticity with temperature can be made locally using sighting shots. This calibration process allows for the derivation of temperature maps from shear wave imaging. Compared with conventional ultrasound-based approaches, shear wave thermometry is found to be much more robust to motion artifacts.

Acoustic waves in the solar atmosphere. VII - Non-grey, non-LTE H(-) models

NASA Technical Reports Server (NTRS)

Schmitz, F.; Ulmschneider, P.; Kalkofen, W.

1985-01-01

The propagation and shock formation of radiatively damped acoustic waves in the solar chromosphere are studied under the assumption that H(-) is the only absorber; the opacity is non-grey. Deviations from local thermodynamic equilibrium (LTE) are permitted. The results of numerical simulations show the depth dependence of the heating by the acoustic waves to be insensitive to the mean state of the atmosphere. After the waves have developed into shocks, their energy flux decays exponentially with a constant damping length of about 1.4 times the pressure scale height, independent of initial flux and wave period. Departures from LTE have a strong influence on the mean temperature structure in dynamical chromosphere models; this is even more pronounced in models with reduced particle density - simulating conditions in magnetic flux tubes - which show significantly increased temperatures in response to mechanical heating. When the energy dissipation of the waves is sufficiently large to dissociate most of the H(-) ions, a strong temperature rise is found that is reminiscent of the temperature structure in the transition zone between chromosphere and corona; the energy flux remaining in the waves then drives mass motions.

Distributed temperature sensors development using an stepped-helical ultrasonic waveguide

NASA Astrophysics Data System (ADS)

Periyannan, Suresh; Rajagopal, Prabhu; Balasubramaniam, Krishnan

2018-04-01

This paper presents the design and development of the distributed ultrasonic waveguide temperature sensors using some stepped-helical structures. Distributed sensing has several applications in various industries (oil, glass, steel) for measurement of physical parameters such as level, temperature, viscosity, etc. This waveguide incorporates a special notch or bend for obtaining ultrasonic wave reflections from the desired locations (Gage-lengths) where local measurements are desired. In this paper, a multi-location measurement wave-guide, with a measurement capability of 18 locations in a single wire, has been fabricated. The distribution of these sensors is both in the axial as well as radial directions using a stepped-helical spring configuration. Also, different high temperature materials have been chosen for the wave-guide. Both lower order axi-symmetric guided ultrasonic modes (L(0,1) and T(0,1)) were employed. These wave modes were generated/received (pulse-echo approach) using conventional longitudinal and shear transducers, respectively. Also, both the wave modes were simultaneously generated/received and compared using shear transducer for developing the distributed helical wave-guide sensors. The effect of dispersion of the wave modes due to curvature effects will also be discussed.

Gravitational waves and Higgs boson couplings for exploring first order phase transition in the model with a singlet scalar field

NASA Astrophysics Data System (ADS)

Hashino, Katsuya; Kakizaki, Mitsuru; Kanemura, Shinya; Ko, Pyungwon; Matsui, Toshinori

2017-03-01

We calculate the spectrum of gravitational waves originated from strongly first order electroweak phase transition in the extended Higgs model with a real singlet scalar field. In order to calculate the bubble nucleation rate, we perform a two-field analysis and evaluate bounce solutions connecting the true and the false vacua using the one-loop effective potential at finite temperatures. Imposing the Sakharov condition of the departure from thermal equilibrium for baryogenesis, we survey allowed regions of parameters of the model. We then investigate the gravitational waves produced at electroweak bubble collisions in the early Universe, such as the sound wave, the bubble wall collision and the plasma turbulence. We find that the strength at the peak frequency can be large enough to be detected at future space-based gravitational interferometers such as eLISA, DECIGO and BBO. Predicted deviations in the various Higgs boson couplings are also evaluated at the zero temperature, and are shown to be large enough too. Therefore, in this model strongly first order electroweak phase transition can be tested by the combination of the precision study of various Higgs boson couplings at the LHC, the measurement of the triple Higgs boson coupling at future lepton colliders and the shape of the spectrum of gravitational wave detectable at future gravitational interferometers.

COMETBOARDS Can Optimize the Performance of a Wave-Rotor-Topped Gas Turbine Engine

NASA Technical Reports Server (NTRS)

Patnaik, Surya N.

1997-01-01

A wave rotor, which acts as a high-technology topping spool in gas turbine engines, can increase the effective pressure ratio as well as the turbine inlet temperature in such engines. The wave rotor topping, in other words, may significantly enhance engine performance by increasing shaft horse power while reducing specific fuel consumption. This performance enhancement requires optimum selection of the wave rotor's adjustable parameters for speed, surge margin, and temperature constraints specified on different engine components. To examine the benefit of the wave rotor concept in engine design, researchers soft coupled NASA Lewis Research Center's multidisciplinary optimization tool COMETBOARDS and the NASA Engine Performance Program (NEPP) analyzer. The COMETBOARDS-NEPP combined design tool has been successfully used to optimize wave-rotor-topped engines. For illustration, the design of a subsonic gas turbine wave-rotor-enhanced engine with four ports for 47 mission points (which are specified by Mach number, altitude, and power-setting combinations) is considered. The engine performance analysis, constraints, and objective formulations were carried out through NEPP, and COMETBOARDS was used for the design optimization. So that the benefits that accrue from wave rotor enhancement could be examined, most baseline variables and constraints were declared to be passive, whereas important parameters directly associated with the wave rotor were considered to be active for the design optimization. The engine thrust was considered as the merit function. The wave rotor engine design, which became a sequence of 47 optimization subproblems, was solved successfully by using a cascade strategy available in COMETBOARDS. The graph depicts the optimum COMETBOARDS solutions for the 47 mission points, which were normalized with respect to standard results. As shown, the combined tool produced higher thrust for all mission points than did the other solution, with maximum benefits around mission points 11, 25, and 31. Such improvements can become critical, especially when engines are sized for these specific mission points.

Kinetic Temperature and Electron Density Measurement in an Inductively Coupled Plasma Torch using Degenerate Four-Wave Mixing

NASA Technical Reports Server (NTRS)

Schafer, Julia; Lyons, Wendy; Tong, WIlliam G.; Danehy, Paul M.

2008-01-01

Laser wave mixing is presented as an effective technique for spatially resolved kinetic temperature measurements in an atmospheric-pressure radio-frequency inductively-coupled plasma. Measurements are performed in a 1 kW, 27 MHz RF plasma using a continuous-wave, tunable 811.5-nm diode laser to excite the 4s(sup 3)P2 approaches 4p(sup 3)D3 argon transition. Kinetic temperature measurements are made at five radial steps from the center of the torch and at four different torch heights. The kinetic temperature is determined by measuring simultaneously the line shape of the sub-Doppler backward phase-conjugate degenerate four-wave mixing and the Doppler-broadened forward-scattering degenerate four-wave mixing. The temperature measurements result in a range of 3,500 to 14,000 K+/-150 K. Electron densities measured range from 6.1 (+/-0.3) x 10(exp 15)/cu cm to 10.1 (+/-0.3) x 10(exp 15)/cu cm. The experimental spectra are analyzed using a perturbative treatment of the backward phase-conjugate and forward-geometry wave-mixing theory. Stark width is determined from the collisional broadening measured in the phase-conjugate geometry. Electron density measurements are made based on the Stark width. The kinetic temperature of the plasma was found to be more than halved by adding deionized water through the nebulizer.

Temperature dependence of current polarization in Ni80Fe20 by spin wave Doppler measurements

NASA Astrophysics Data System (ADS)

Zhu, Meng; Dennis, Cindi; McMichael, Robert

2010-03-01

The temperature dependence of current polarization in ferromagnetic metals will be important for operation of spin-torque switched memories and domain wall devices in a wide temperature range. Here, we use the spin wave Doppler technique[1] to measure the temperature dependence of both the magnetization drift velocity v(T) and the current polarization P(T) in Ni80Fe20. We obtain these values from current-dependent shifts of the spin wave transmission resonance frequency for fixed-wavelength spin waves in current-carrying wires. For current densities of 10^11 A/m^2, we obtain v(T) decreasing from 4.8 ±0.3 m/s to 4.1 ±0.1 m/s and P(T) dropping from 0.75±0.05 to 0.58±0.02 over a temperature range from 80 K to 340 K. [1] V. Vlaminck et al. Science 322, 410 (2008);

Temperature dependences of the electric polarization and wave number of incommensurate structures in multiferroics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pikin, S. A., E-mail: pikin@ns.crys.ras.ru

2016-05-15

It is shown that the electric polarization and wave number of incommensurate modulations, proportional to each other, increase according to the Landau law in spin multiferroic cycloids near the Néel temperature. In this case, the constant magnetization component (including the one for a conical spiral) is oriented perpendicular to the spin incommensurability wave vector. A similar temperature behavior should manifest itself for spin helicoids, the axes of which are oriented parallel to the polarization vector but their spin rotation planes are oriented perpendicular to the antiferromagnetic order plane. When the directions of axes of the magnetization helicoid and polarization vectormore » coincide, the latter is quadratic with respect to magnetization and linearly depends on temperature, whereas the incommensurate-modulation wave number barely depends on temperature. Structural distortions of unit cells for multiferroics of different types determine their axial behavior.« less

Parameter variation effects on temperature elevation in a steady-state, one-dimensional thermal model for millimeter wave exposure of one- and three-layer human tissue.

PubMed

Kanezaki, Akio; Hirata, Akimasa; Watanabe, Soichi; Shirai, Hiroshi

2010-08-21

The present study describes theoretical parametric analysis of the steady-state temperature elevation in one-dimensional three-layer (skin, fat and muscle) and one-layer (skin only) models due to millimeter-wave exposure. The motivation of this fundamental investigation is that some variability of warmth sensation in the human skin has been reported. An analytical solution for a bioheat equation was derived by using the Laplace transform for the one-dimensional human models. Approximate expressions were obtained to investigate the dependence of temperature elevation on different thermal and tissue thickness parameters. It was shown that the temperature elevation on the body surface decreases monotonically with the blood perfusion rate, heat conductivity and heat transfer from the body to air. Also revealed were the conditions where maximum and minimum surface temperature elevations were observed for different thermal and tissue thickness parameters. The surface temperature elevation in the three-layer model is 1.3-2.8 times greater than that in the one-layer model. The main reason for this difference is attributed to the adiabatic nature of the fat layer. By considering the variation range of thermal and tissue thickness parameters which causes the maximum and minimum temperature elevations, the dominant parameter influencing the surface temperature elevation was found to be the heat transfer coefficient between the body surface and air.

Connection between in-plane upper critical field Hc 2 and gap symmetry in layered d -wave superconductors

NASA Astrophysics Data System (ADS)

Wang, Jing-Rong; Liu, Guo-Zhu; Zhang, Chang-Jin

2016-07-01

Angle-resolved upper critical field Hc 2 provides an efficient tool to probe the gap symmetry of unconventional superconductors. We revisit the behavior of in-plane Hc 2 in d -wave superconductors by considering both the orbital effect and Pauli paramagnetic effect. After carrying out systematic analysis, we show that the maxima of Hc 2 could be along either nodal or antinodal directions of a d -wave superconducting gap, depending on the specific values of a number of tuning parameters. This behavior is in contrast to the common belief that the maxima of in-plane Hc 2 are along the direction where the superconducting gap takes its maximal value. Therefore, identifying the precise d -wave gap symmetry through fitting experiments results of angle-resolved Hc 2 with model calculations at a fixed temperature, as widely used in previous studies, is difficult and practically unreliable. However, our extensive analysis of angle-resolved Hc 2 show that there is a critical temperature T*: in-plane Hc 2 exhibits its maxima along nodal directions at T

EASI - EQUILIBRIUM AIR SHOCK INTERFERENCE

NASA Technical Reports Server (NTRS)

Glass, C. E.

1994-01-01

New research on hypersonic vehicles, such as the National Aero-Space Plane (NASP), has raised concerns about the effects of shock-wave interference on various structural components of the craft. State-of-the-art aerothermal analysis software is inadequate to predict local flow and heat flux in areas of extremely high heat transfer, such as the surface impingement of an Edney-type supersonic jet. EASI revives and updates older computational methods for calculating inviscid flow field and maximum heating from shock wave interference. The program expands these methods to solve problems involving the six shock-wave interference patterns on a two-dimensional cylindrical leading edge with an equilibrium chemically reacting gas mixture (representing, for example, the scramjet cowl of the NASP). The inclusion of gas chemistry allows for a more accurate prediction of the maximum pressure and heating loads by accounting for the effects of high temperature on the air mixture. Caloric imperfections and specie dissociation of high-temperature air cause shock-wave angles, flow deflection angles, and thermodynamic properties to differ from those calculated by a calorically perfect gas model. EASI contains pressure- and temperature-dependent thermodynamic and transport properties to determine heating rates, and uses either a calorically perfect air model or an 11-specie, 7-reaction reacting air model at equilibrium with temperatures up to 15,000 K for the inviscid flowfield calculations. EASI solves the flow field and the associated maximum surface pressure and heat flux for the six common types of shock wave interference. Depending on the type of interference, the program solves for shock-wave/boundary-layer interaction, expansion-fan/boundary-layer interaction, attaching shear layer or supersonic jet impingement. Heat flux predictions require a knowledge (from experimental data or relevant calculations) of a pertinent length scale of the interaction. Output files contain flow-field information for the various shock-wave interference patterns and their associated maximum surface pressure and heat flux predictions. EASI is written in FORTRAN 77 for a DEC VAX 8500 series computer using the VAX/VMS operating system, and requires 75K of memory. The program is available on a 9-track 1600 BPI magnetic tape in DEC VAX BACKUP format. EASI was developed in 1989. DEC, VAX, and VMS are registered trademarks of the Digital Equipment Corporation.

Percentage Contributions from Atmospheric and Surface Features to Computed Brightness Temperatures

NASA Technical Reports Server (NTRS)

Jackson, Gail Skofronick

2006-01-01

Over the past few years, there has become an increasing interest in the use of millimeter-wave (mm-wave) and sub-millimeter-wave (submm-wave) radiometer observations to investigate the properties of ice particles in clouds. Passive radiometric channels respond to both the integrated particle mass throughout the volume and field of view, and to the amount, location, and size distribution of the frozen (and liquid) particles with the sensitivity varying for different frequencies and hydrometeor types. One methodology used since the 1960's to discern the relationship between the physical state observed and the brightness temperature (TB) is through the temperature weighting function profile. In this research, the temperature weighting function concept is exploited to analyze the sensitivity of various characteristics of the cloud profile, such as relative humidity, ice water path, liquid water path, and surface emissivity. In our numerical analysis, we compute the contribution (in Kelvin) from each of these cloud and surface characteristics, so that the sum of these various parts equals the computed TB. Furthermore, the percentage contribution from each of these characteristics is assessed. There is some intermingling/contamination of the contributions from various components due to the integrated nature of passive observations and the absorption and scattering between the vertical layers, but all in all the knowledge gained is useful. This investigation probes the sensitivity over several cloud classifications, such as cirrus, blizzards, light snow, anvil clouds, and heavy rain. The focus is on mm-wave and submm-wave frequencies, however discussions of the effects of cloud variations to frequencies as low as 10 GHz and up to 874 GHz will also be presented. The results show that nearly 60% of the TB value at 89 GHz comes from the earth's surface for even the heaviest blizzard snow rates. On the other hand, a significant percentage of the TB value comes from the snow in the cloud for 166, and 183 plus or minus 7 GHz for the heavy and medium snow rates. For submm-wave channels, there is no contribution from the surface because these channels cannot probe through clouds, nor normal water vapor amounts in clear air regions. This work is extremely valuable in physically-based retrieval algorithm development research.

Thermomagnetic convective flows in a vertical layer of ferrocolloid: perturbation energy analysis and experimental study.

PubMed

Suslov, Sergey A; Bozhko, Alexandra A; Sidorov, Alexander S; Putin, Gennady F

2012-07-01

Flow patterns arising in a vertical differentially heated layer of nonconducting ferromagnetic fluid placed in an external uniform transverse magnetic field are studied experimentally and discussed from the point of view of the perturbation energy balance. A quantitative criterion for detecting the parametric point where the dominant role in generating a flow instability is transferred between the thermogravitational and thermomagnetic mechanisms is suggested, based on the disturbance energy balance analysis. A comprehensive experimental study of various flow patterns is undertaken, and the existence is demonstrated of oblique thermomagnetic waves theoretically predicted by Suslov [Phys. Fluids 20, 084101 (2008)] and superposed onto the stationary magnetoconvective pattern known previously. It is found that the wave number of the detected convection patterns depends sensitively on the temperature difference across the layer and on the applied magnetic field. In unsteady regimes its value varies periodically by a factor of almost 2, indicating the appearance of two different competing wave modes. The wave numbers and spatial orientation of the observed dominant flow patterns are found to be in good agreement with theoretical predictions.

Multiple and exact soliton solutions of the perturbed Korteweg-de Vries equation of long surface waves in a convective fluid via Painlevé analysis, factorization, and simplest equation methods.

PubMed

Selima, Ehab S; Yao, Xiaohua; Wazwaz, Abdul-Majid

2017-06-01

In this research, the surface waves of a horizontal fluid layer open to air under gravity field and vertical temperature gradient effects are studied. The governing equations of this model are reformulated and converted to a nonlinear evolution equation, the perturbed Korteweg-de Vries (pKdV) equation. We investigate the latter equation, which includes dispersion, diffusion, and instability effects, in order to examine the evolution of long surface waves in a convective fluid. Dispersion relation of the pKdV equation and its properties are discussed. The Painlevé analysis is applied not only to check the integrability of the pKdV equation but also to establish the Bäcklund transformation form. In addition, traveling wave solutions and a general form of the multiple-soliton solutions of the pKdV equation are obtained via Bäcklund transformation, the simplest equation method using Bernoulli, Riccati, and Burgers' equations as simplest equations, and the factorization method.

Survey of Temperature Measurement Techniques For Studying Underwater Shock Waves

NASA Technical Reports Server (NTRS)

Danehy, Paul M.; Alderfer, David W.

2004-01-01

Several optical methods for measuring temperature near underwater shock waves are reviewed and compared. The relative merits of the different techniques are compared, considering accuracy, precision, ease of use, applicable temperature range, maturity, spatial resolution, and whether or not special additives are required.

Peripheral circulatory disorders in essential thrombocythemia.

PubMed

Małecki, Rafał; Gacka, Małgorzata; Fiodorenko-Dumas, Żanna; Dumas, Ilias; Kwiatkowski, Jacek; Adamiec, Rajmund; Kuliszkiewicz-Janus, Małgorzata

2018-03-01

A significant number of patients with essential thrombocythemia (ET) complain of symptoms including distal parts of the extremities (e.g., paresthesias or Raynaud's phenomenon). The aim of the present study was to examine peripheral circulation in the upper extremities of individuals with ET. The study included 45 ET patients and 30 control subjects. All participants were subjected to thermography, photoplethysmography, impedance plethysmography, and applanation tonometry pulse wave analysis. The patients with ET differed significantly from the control subjects in terms of 3rd finger skin temperature (mean 31.04 vs. 32.45°C), skin temperature gradient (mean 1.82 vs. 0.11°C), photoplethysmographic amplitude (median 0.25 vs. 0.74%), and pulse waveform in the radial artery (more frequent occurrence of type B waveform). Pulse wave parameters correlated with the skin temperature gradient. The study findings imply the altered regulation of peripheral circulation in ET, including a decreased flow and an increased resistance. Copyright © 2017 Elsevier Inc. All rights reserved.

Noncontacting acoustics-based temperature measurement techniques in rapid thermal processing

NASA Astrophysics Data System (ADS)

Lee, Yong J.; Chou, Ching-Hua; Khuri-Yakub, Butrus T.; Saraswat, Krishna C.

1991-04-01

Temperature measurement of silicon wafers based on the temperature dependence of acoustic waves is studied. The change in the temperature-dependent dispersion relations of the plate modes through the wafer can be exploited to provide a viable temperature monitoring scheme with advantages over both thermocouples and pyrometers. Velocity measurements of acoustic waves through a thin layer of ambient directly above the wafer provides the temperature of the wafer-ambient interface. 1.

Coastal Circulation and Sediment Dynamics in Hanalei Bay, Kaua'i, Part IV, Measurements of Waves, Currents, Temperature, Salinity, and Turbidity, June-September 2006

USGS Publications Warehouse

Storlazzi, Curt D.; Presto, M. Katherine; Logan, Joshua B.; Field, Michael E.

2008-01-01

High-resolution measurements of waves, currents, water levels, temperature, salinity and turbidity were made in Hanalei Bay, northern Kaua'i, Hawai'i, during the summer of 2006 to better understand coastal circulation, sediment dynamics, and the potential impact of a river flood in a coral reef-lined embayment during quiescent summer conditions. A series of bottommounted instrument packages were deployed in water depths of 10 m or less to collect long-term, high-resolution measurements of waves, currents, water levels, temperature, salinity, and turbidity. These data were supplemented with a series of profiles through the water column to characterize the vertical and spatial variability in water column properties within the bay. These measurements support the ongoing process studies being conducted as part of the U.S. Geological Survey (USGS) Coastal and Marine Geology Program's Pacific Coral Reef Project; the ultimate goal is to better understand the transport mechanisms of sediment, larvae, pollutants, and other particles in coral reef settings. Information regarding the USGS study conducted in Hanalei Bay during the 2005 summer is available in Storlazzi and others (2006), Draut and others (2006) and Carr and others (2006). This report, the last part in a series, describes data acquisition, processing, and analysis for the 2006 summer data set.

Leading modes of tropical Pacific subsurface ocean temperature and associations with two types of El Niño.

PubMed

Zhang, Zhiyuan; Ren, Baohua; Zheng, Jianqiu

2017-02-17

Using empirical orthogonal function (EOF) analysis of the monthly tropical Pacific subsurface ocean temperature anomalies (SOTA) from 1979 to 2014, we detected three leading modes in the tropical Pacific subsurface temperature. The first mode has a dipole pattern, with warming in the eastern Pacific and cooling in the western Pacific, and is closely related to traditional El Niño. The second mode has a monopole pattern, with only warming in the central Pacific subsurface. The third mode has a zonal tripole pattern, with warming in the off-equatorial central Pacific and cooling in the far eastern Pacific and western Pacific. The second and third modes are both related to El Niño Modoki. Mode 1 is linked with a Kelvin wave that propagates from the central to the eastern Pacific and is induced by the anomalous westerlies that propagate from the western to the central Pacific. Mode 2 is also linked with a Kelvin wave that propagates from the western to the central Pacific induced by the enhancement of westerlies over the western Pacific. Mode 3 is linked with a Rossby wave that propagates from the central to the western Pacific driven by the anomalous easterlies over the eastern Pacific.

Intercomparison of AIRS and HIRDLS stratospheric gravity wave observations

NASA Astrophysics Data System (ADS)

Meyer, Catrin I.; Ern, Manfred; Hoffmann, Lars; Trinh, Quang Thai; Alexander, M. Joan

2018-01-01

We investigate stratospheric gravity wave observations by the Atmospheric InfraRed Sounder (AIRS) aboard NASA's Aqua satellite and the High Resolution Dynamics Limb Sounder (HIRDLS) aboard NASA's Aura satellite. AIRS operational temperature retrievals are typically not used for studies of gravity waves, because their vertical and horizontal resolution is rather limited. This study uses data of a high-resolution retrieval which provides stratospheric temperature profiles for each individual satellite footprint. Therefore the horizontal sampling of the high-resolution retrieval is 9 times better than that of the operational retrieval. HIRDLS provides 2-D spectral information of observed gravity waves in terms of along-track and vertical wavelengths. AIRS as a nadir sounder is more sensitive to short-horizontal-wavelength gravity waves, and HIRDLS as a limb sounder is more sensitive to short-vertical-wavelength gravity waves. Therefore HIRDLS is ideally suited to complement AIRS observations. A calculated momentum flux factor indicates that the waves seen by AIRS contribute significantly to momentum flux, even if the AIRS temperature variance may be small compared to HIRDLS. The stratospheric wave structures observed by AIRS and HIRDLS often agree very well. Case studies of a mountain wave event and a non-orographic wave event demonstrate that the observed phase structures of AIRS and HIRDLS are also similar. AIRS has a coarser vertical resolution, which results in an attenuation of the amplitude and coarser vertical wavelengths than for HIRDLS. However, AIRS has a much higher horizontal resolution, and the propagation direction of the waves can be clearly identified in geographical maps. The horizontal orientation of the phase fronts can be deduced from AIRS 3-D temperature fields. This is a restricting factor for gravity wave analyses of limb measurements. Additionally, temperature variances with respect to stratospheric gravity wave activity are compared on a statistical basis. The complete HIRDLS measurement period from January 2005 to March 2008 is covered. The seasonal and latitudinal distributions of gravity wave activity as observed by AIRS and HIRDLS agree well. A strong annual cycle at mid- and high latitudes is found in time series of gravity wave variances at 42 km, which has its maxima during wintertime and its minima during summertime. The variability is largest during austral wintertime at 60° S. Variations in the zonal winds at 2.5 hPa are associated with large variability in gravity wave variances. Altogether, gravity wave variances of AIRS and HIRDLS are complementary to each other. Large parts of the gravity wave spectrum are covered by joint observations. This opens up fascinating vistas for future gravity wave research.

The high temperature impact response of tungsten and chromium

NASA Astrophysics Data System (ADS)

Zaretsky, E. B.; Kanel, G. I.

2017-09-01

The evolution of elastic-plastic shock waves has been studied in pure polycrystalline tungsten and chromium at room and elevated temperatures over propagation distances ranging from 0.05 to 3 mm (tungsten) and from 0.1 to 2 mm (chromium). The use of fused silica windows in all but one experiment with chromium and in several high temperature experiments with tungsten led to the need for performing shock and optic characterization of these windows over the 300-1200 K temperature interval. Experiments with tungsten and chromium samples showed that annealing of the metals transforms the initial ramping elastic wave into a jump-like wave, substantially increasing the Hugoniot elastic limits of the metals. With increased annealing time, the spall strength of the two metals slightly increases. Both at room and at high temperatures, the elastic precursor in the two metals decays in two distinct regimes. At propagation distances smaller than ˜1 mm (tungsten) or ˜0.5 mm (chromium), decay is fast, with the dislocation motion and multiplication being controlled by phonon viscous drag. At greater distances, the rate of decay becomes much lower, with control of the plastic deformation being passed to the thermally activated generation and motion of dislocation double-kinks. The stress at which this transition takes place virtually coincides with the Peierls stress τP of the active glide system. Analysis of the annealing effects in both presently and previously studied BCC metals (i.e., Ta, V, Nb, Mo, W, and Cr) and of the dependencies of their normalized Peierls stresses τP(θ) /τP(0 ) on the normalized temperature θ=T /Tm allows one to conclude that the non-planar, split into several glide planes, structure of the dislocation core in these metals is mainly responsible for their plastic deformation features.

Effect of heat waves on morbidity and mortality due to Parkinson's disease in Madrid: A time-series analysis.

PubMed

Linares, Cristina; Martinez-Martin, Pablo; Rodríguez-Blázquez, Carmen; Forjaz, Maria João; Carmona, Rocío; Díaz, Julio

2016-01-01

Parkinson's disease (PD) is one of the factors which are associated with a higher risk of mortality during heat waves. The use of certain neuroleptic medications to control some of this disease's complications would appear to be related to an increase in heat-related mortality. To analyse the relationship and quantify the short-term effect of high temperatures during heat wave episodes in Madrid on daily mortality and PD-related hospital admissions. We used an ecological time-series study and fit Poisson regression models. We analysed the daily number of deaths due to PD and the number of daily PD-related emergency hospital admissions in the city of Madrid, using maximum daily temperature (°C) as the main environmental variable and chemical air pollution as covariates. We controlled for trend, seasonalities, and the autoregressive nature of the series. There was a maximum daily temperature of 30°C at which PD-related admissions were at a minimum. Similarly, a temperature of 34°C coincides with an increase in the number of admissions. For PD-related admissions, the Relative Risk (RR) for every increase of 1°C above the threshold temperature was 1.13 IC95%:(1.03-1.23) at lags 1 and 5; and for daily PD-related mortality, the RR was 1.14 IC95%:(1.01-1.28) at lag 3. Our results indicate that suffering from PD is a risk factor that contributes to the excess morbidity and mortality associated with high temperatures, and is relevant from the standpoint of public health prevention plans. Copyright © 2016 Elsevier Ltd. All rights reserved.

CFD Analysis of Experimental Wing and Winglet for FalconLAUNCH 8 and the ExFIT Program

DTIC Science & Technology

2010-03-01

CFD Analysis of Experimental Wing and Winglet for FalconLAUNCH 8 and the ExFIT Program THESIS Benjamin P. Switzer, Second Lieutenant, USAF AFIT/GAE...to copyright protection in the United States. AFIT/GAE/ENY/10-M25 CFD Analysis of Experimental Wing and Winglet for FalconLAUNCH 8 and the ExFIT...this analysis focused on the effects caused by shock waves forming on the winglet and their impact on the lifting characteristics and temperature

A numerical and experimental study of temperature effects on deformation behavior of carbon steels at high strain rates

NASA Astrophysics Data System (ADS)

Pouya, M.; Winter, S.; Fritsch, S.; F-X Wagner, M.

2017-03-01

Both in research and in the light of industrial applications, there is a growing interest in methods to characterize the mechanical behavior of materials at high strain rates. This is particularly true for steels (the most important structural materials), where often the strain rate-dependent material behavior also needs to be characterized in a wide temperature range. In this study, we use the Finite Element Method (FEM), first, to model the compressive deformation behavior of carbon steels under quasi-static loading conditions. The results are then compared to experimental data (for a simple C75 steel) at room temperature, and up to testing temperatures of 1000 °C. Second, an explicit FEM model that captures wave propagation phenomena during dynamic loading is developed to closely reflect the complex loading conditions in a Split-Hopkinson Pressure Bar (SHPB) - an experimental setup that allows loading of compression samples with strain rates up to 104 s-1 The dynamic simulations provide a useful basis for an accurate analysis of dynamically measured experimental data, which considers reflected elastic waves. By combining numerical and experimental investigations, we derive material parameters that capture the strain rate- and temperature-dependent behavior of the C75 steel from room temperature to 1000 °C, and from quasi-static to dynamic loading.

Estimation of the activation energy in the Belousov-Zhabotinsky reaction by temperature effect on excitable waves.

PubMed

Zhang, Jinzhong; Zhou, Luqun; Ouyang, Qi

2007-02-15

We report the temperature effect on the propagation of excitable traveling waves in a quasi-two-dimensional Belousov-Zhabotinsky reaction-diffusion system. The onset of excitable waves as a function of the sulfuric acid concentration and temperature is identified, on which the sulfuric acid concentration exhibits an Arrhenius dependence on temperature. On the basis of this experimental data, the activation energy of the self-catalyzed reaction in the Oregonator model is estimated to be 83-113 kJ/mol, which is further supported by our numerical simulations. The estimation proceeds without analyzing detailed reaction steps but rather through observing the global dynamic behaviors in the BZ reaction. For a supplement, the wave propagation velocities are calculated based on our results and compared with the experimental observations.

What Controls the Temperature of the Arctic Stratosphere during the Spring?

NASA Technical Reports Server (NTRS)

Newman, Paul A.; Nash, Eric R.; Rosenfield, Joan E.; Einaudi, Franco (Technical Monitor)

2000-01-01

Understanding the mechanisms that control the temperature of the polar lower stratosphere during spring is key to understanding ozone loss in the Arctic polar vortex. Spring ozone loss rates are directly tied to polar stratospheric temperatures by the formation of polar stratospheric clouds, and the conversion of chlorine species to reactive forms on these cloud particle surfaces. In this paper, we study those factors that control temperatures in the polar lower stratosphere. We use the National Centers for Environmental Prediction (NCEP)/NCAR reanalysis data covering the last two decades to investigate how planetary wave driving of the stratosphere is connected to polar temperatures. In particular, we show that planetary waves forced in the troposphere in mid- to late winter (January-February) are principally responsible for the mean polar temperature during the March period. These planetary waves are forced by both thermal and orographic processes in the troposphere, and propagate into the stratosphere in the mid and high latitudes. Strong mid-winter planetary wave forcing leads to a warmer Arctic lower stratosphere in early spring, while weak mid-winter forcing leads to cooler Arctic temperatures.

Projection of temperature and heat waves for Africa with an ensemble of CORDEX Regional Climate Models

NASA Astrophysics Data System (ADS)

Dosio, Alessandro

2017-07-01

The most severe effects of global warning will be related to the frequency and severity of extreme events. We provide an analysis of projections of temperature and related extreme events for Africa based on a large ensemble of Regional Climate Models from the COordinated Regional climate Downscaling EXperiment (CORDEX). Results are presented not only by means of widely used indices but also with a recently developed Heat Wave Magnitude Index-daily (HWMId), which takes into account both heat wave duration and intensity. Results show that under RCP8.5, warming of more than 3.5 °C is projected in JFM over most of the continent, whereas in JAS temperatures over large part of Northern Africa, the Sahara and the Arabian peninsula are projected to increase up to 6 °C. Large increase in in the number of warm days (Tx90p) is found over sub equatorial Africa, with values up to more than 90 % in JAS, and more than 80 % in JFM over e.g., the gulf of Guinea, Central African Republic, South Sudan and Ethiopia. Changes in Tn90p (warm nights) are usually larger, with some models projecting Tn90p reaching 95 % starting from around 2060 even under RCP4.5 over the Gulf of Guinea and the Sahel. Results also show that the total length of heat spells projected to occur normally (i.e. once every 2 years) under RCP8.5 may be longer than those occurring once every 30 years under the lower emission scenario. By employing the recently developed HWMId index, it is possible to investigate the relationship between heat wave length ad intensity; in particular it is shown that very intense heat waves such as that occurring over the Horn of Africa may have values of HWMId larger than that of longer, but relatively weak, heat waves over West Africa.

High temperature measurement of water vapor absorption

NASA Technical Reports Server (NTRS)

Keefer, Dennis; Lewis, J. W. L.; Eskridge, Richard

1985-01-01

An investigation was undertaken to measure the absorption coefficient, at a wavelength of 10.6 microns, for mixtures of water vapor and a diluent gas at high temperature and pressure. The experimental concept was to create the desired conditions of temperature and pressure in a laser absorption wave, similar to that which would be created in a laser propulsion system. A simplified numerical model was developed to predict the characteristics of the absorption wave and to estimate the laser intensity threshold for initiation. A non-intrusive method for temperature measurement utilizing optical laser-beam deflection (OLD) and optical spark breakdown produced by an excimer laser, was thoroughly investigated and found suitable for the non-equilibrium conditions expected in the wave. Experiments were performed to verify the temperature measurement technique, to screen possible materials for surface initiation of the laser absorption wave and to attempt to initiate an absorption wave using the 1.5 kW carbon dioxide laser. The OLD technique was proven for air and for argon, but spark breakdown could not be produced in helium. It was not possible to initiate a laser absorption wave in mixtures of water and helium or water and argon using the 1.5 kW laser, a result which was consistent with the model prediction.

Acceleration and heating of two-fluid solar wind by Alfven waves

NASA Technical Reports Server (NTRS)

Sandbaek, Ornulf; Leer, Egil

1994-01-01

Earlier model studies of solar wind driven by thermal pressure and Alfven waves have shown that wave amplitudes of 20-30 km/s at the coronal base are sufficient to accelerate the flow to the high speeds observed in quasi-steady streams emanating from large coronal holes. We focus on the energy balance in the proton gas and show that heat conduction from the region where the waves are dissipated may play an important role in determining the proton temperature at the orbit of Earth. In models with 'classical' heat conduction we find a correlation between high flow speed, high proton temperature, and low electron temperature at 1 AU. The effect of wave heating on the development of anisotropies in the solar wind proton gas pressure is also investigated in this study.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Dae Jung; Lee, Dong-Hun; Kim, Kihong

We study theoretically the linear mode conversion between electromagnetic waves and Langmuir waves in warm, stratified, and unmagnetized plasmas, using a numerically precise calculation based on the invariant imbedding method. We verify that the principle of reciprocity for the forward and backward mode conversion coefficients holds precisely regardless of temperature. We also find that the temperature dependence of the mode conversion coefficient is substantially stronger than that previously reported. Depending on the wave frequency and the incident angle, the mode conversion coefficient is found to increase or decrease with the increase of temperature.

Contactless ultrasonic device to measure surface acoustic wave velocities versus temperature.

PubMed

Hubert, C; Nadal, M H; Ravel-Chapuis, G; Oltra, R

2007-02-01

A complete optical experimental setup for generating and detecting surface acoustic waves [Rayleigh waves (RWs)] in metals versus temperature up to the melting point is described. The RWs were excited by a pulsed Nd:YAG laser and detected by a high sensitivity subangstrom heterodyne interferometer. A special furnace was used to heat the sample using infrared radiation with a regulation of the sample temperature less than 0.1 K. First measurements on an aluminum alloy sample are presented to validate the setup.

Van Allen Probe Observations of Chorus Wave Activity, Source and Seed electrons, and the Radiation Belt Response During ICME and CIR Storms

NASA Astrophysics Data System (ADS)

Bingham, S.; Mouikis, C.; Kistler, L. M.; Farrugia, C. J.; Paulson, K. W.; Huang, C. L.; Boyd, A. J.; Spence, H. E.; Kletzing, C.

2017-12-01

Whistler mode chorus waves are electromagnetic waves that have been shown to be a major contributor to enhancements in the outer radiation belt during geomagnetic storms. The temperature anisotropy of source electrons (10s of keV) provides the free energy for chorus waves, which can accelerate sub-relativistic seed electrons (100s of keV) to relativistic energies. This study uses Van Allen Probe observations to examine the excitation and plasma conditions associated with chorus wave observations, the development of the seed population, and the outer radiation belt response in the inner magnetosphere, for 25 ICME and 35 CIR storms. Plasma data from the Helium Oxygen Proton Electron (HOPE) instrument and magnetic field measurements from the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) are used to identify chorus wave activity and to model a linear theory based proxy for chorus wave growth. A superposed epoch analysis shows a peak of chorus wave power on the dawnside during the storm main phase that spreads towards noon during the storm recovery phase. According to the linear theory results, this wave activity is driven by the enhanced convection driving plasma sheet electrons across the dayside. Both ICME and CIR storms show comparable levels of wave growth. Plasma data from the Magnetic Electron Ion Spectrometer (MagEIS) and the Relativistic Electron Proton Telescope (REPT) are used to observe the seed and relativistic electrons. A superposed epoch analysis of seed and relativistic electrons vs. L shows radiation belt enhancements with much greater frequency in the ICME storms, coinciding with a much stronger and earlier seed electron enhancement in the ICME storms.

In vivo analysis of THz wave irradiation induced acute inflammatory response in skin by laser-scanning confocal microscopy.

PubMed

Hwang, Yoonha; Ahn, Jinhyo; Mun, Jungho; Bae, Sangyoon; Jeong, Young Uk; Vinokurov, Nikolay A; Kim, Pilhan

2014-05-19

The recent development of THz sources in a wide range of THz frequencies and power levels has led to greatly increased interest in potential biomedical applications such as cancer and burn wound diagnosis. However, despite its importance in realizing THz wave based applications, our knowledge of how THz wave irradiation can affect a live tissue at the cellular level is very limited. In this study, an acute inflammatory response caused by pulsed THz wave irradiation on the skin of a live mouse was analyzed at the cellular level using intravital laser-scanning confocal microscopy. Pulsed THz wave (2.7 THz, 4 μs pulsewidth, 61.4 μJ per pulse, 3Hz repetition), generated using compact FEL, was used to irradiate an anesthetized mouse's ear skin with an average power of 260 mW/cm(2) for 30 minutes using a high-precision focused THz wave irradiation setup. In contrast to in vitro analysis using cultured cells at similar power levels of CW THz wave irradiation, no temperature change at the surface of the ear skin was observed when skin was examined with an IR camera. To monitor any potential inflammatory response, resident neutrophils in the same area of ear skin were repeatedly visualized before and after THz wave irradiation using a custom-built laser-scanning confocal microscopy system optimized for in vivo visualization. While non-irradiated control skin area showed no changes in the number of resident neutrophils, a massive recruitment of newly infiltrated neutrophils was observed in the THz wave irradiated skin area after 6 hours, which suggests an induction of acute inflammatory response by the pulsed THz wave irradiation on the skin via a non-thermal process.

Nonlinear dust-acoustic structures in space plasmas with superthermal electrons, positrons, and ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saberian, E., E-mail: e.saberian@neyshabur.ac.ir; Esfandyari-Kalejahi, A.; Afsari-Ghazi, M.

Some features of nonlinear dust-acoustic (DA) structures are investigated in a space plasma consisting of superthermal electrons, positrons, and positive ions in the presence of negatively charged dust grains with finite-temperature by employing a pseudo-potential technique in a hydrodynamic model. For this purpose, it is assumed that the electrons, positrons, and ions obey a kappa-like (κ) distribution in the background of adiabatic dust population. In the linear analysis, it is found that the dispersion relation yield two positive DA branches, i.e., the slow and fast DA waves. The upper branch (fast DA waves) corresponds to the case in which bothmore » (negatively charged) dust particles and (positively charged) ion species oscillate in phase with electrons and positrons. On the other hand, the lower branch (slow DA waves) corresponds to the case in which only dust particles oscillate in phase with electrons and positrons, while ion species are in antiphase with them. On the other hand, the fully nonlinear analysis shows that the existence domain of solitons and their characteristics depend strongly on the dust charge, ion charge, dust temperature, and the spectral index κ. It is found that the minimum/maximum Mach number increases as the spectral index κ increases. Also, it is found that only solitons with negative polarity can propagate and that their amplitudes increase as the parameter κ increases. Furthermore, the domain of Mach number shifts to the lower values, when the value of the dust charge Z{sub d} increases. Moreover, it is found that the Mach number increases with an increase in the dust temperature. Our analysis confirms that, in space plasmas with highly charged dusts, the presence of superthermal particles (electrons, positrons, and ions) may facilitate the formation of DA solitary waves. Particularly, in two cases of hydrogen ions H{sup +} (Z{sub i} = 1) and doubly ionized Helium atoms He{sup 2+} (Z{sub i} = 2), the mentioned results are the same. Additionally, the mentioned dusty plasma does not support DA solitons with positive polarity (compressive solitons). Furthermore, our analysis confirms that DA double layers cannot exist in such a system. Moreover, the positron density has not a considerable effect on the behavior of DA solitons in our model.« less

Temperature Effect on the Dispersion Relation of Nonequilibrium Exciton-Polariton Condensates in a CuBr Microcavity

NASA Astrophysics Data System (ADS)

Nakayama, Masaaki; Tamura, Kazuki

2018-05-01

We observed the dispersion relation of nonequilibrium exciton-polariton condensates at 10 and 80 K in a CuBr microcavity using angle-resolved photoluminescence spectroscopy. The dispersion relation consists of dispersionless and dispersive parts in small and large in-plane wave vector regions, respectively. It was found that the cutoff wave vector of the dispersionless region at 80 K is larger than that at 10 K. From quantitative analysis of the dispersion relation based on a theory for nonequilibrium condensation, we show that the larger cutoff wave vector results from an increase in the effective relaxation rate of the Bogoliubov mode in equilibrium condensation; namely, a degree of nonequilibrium at 80 K is higher than that at 10 K.

Altitude and intensity characteristics of parametric instability excited by an HF pump wave near the fifth electron harmonic

NASA Astrophysics Data System (ADS)

Jun, WU; Jian, WU; M, T. RIETVELD; I, HAGGSTROM; Haisheng, ZHAO; Zhengwen, XU

2017-12-01

An ionospheric heating experiment involving an O mode pump wave was carried out at European Incoherent Scatter Scientific Association site in Tromsø. The observation of the ultra high frequency radar illustrates the systematic variations of the enhanced ion line and plasma line in altitude and intensity as a function of the pump frequency. The analysis shows that those altitude variations are due to the thermal effect, and the intensity variations of the enhanced ion line are dependent on whether or not the enhanced ion acoustic wave satisfy the Bragg condition of radar. Moreover, a prediction that if the enhancement in electron temperature is suppressed, those systematic variations will be absent, is given.

Low-Temperature Sterilization with Surface-Wave-Excited Oxygen Plasma

NASA Astrophysics Data System (ADS)

Nagatsu, Masaaki; Terashita, Fumie; Koide, Yukio

2003-07-01

Low-temperature plasma sterilization has been experimentally demonstrated using surface-wave plasma excited by a 2.45 GHz microwave. With the spores of Bacillus stearothermophilus and Bacillus subtilis as biological indicators, we have carried out the plasma sterilization experiments by varying the irradiation period of oxygen plasma discharges. It was experimentally confirmed that the spores with a population of 1.5 × 106 were sterilized by irradiating them with oxygen plasma discharges generated with a microwave power of 700 W at a pressure of 60-80 mTorr for 3 min or longer. From the scanning electron microscopy (SEM) analysis of the spores, we found that the sterilized spores clearly had different sizes and shapes compared with those before the plasma irradiation. Furthermore, present experiments suggested that the changes of spore shapes were mainly attributed to the reactive interactions with oxygen radicals.

Phonon wave interference in graphene and boron nitride superlattice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Xue-Kun; Zhou, Wu-Xing; Tang, Li-Ming

2016-07-11

The thermal transport properties of the graphene and boron nitride superlattice (CBNSL) are investigated via nonequilibrium molecular dynamics simulations. The simulation results show that a minimum lattice thermal conductivity can be achieved by changing the period length of the superlattice. Additionally, it is found that the period length at the minimum shifts to lower values at higher temperatures, and that the depth of the minimum increases with decreasing temperature. In particular, at 200 K, the thermal conductivities of CBNSLs with certain specific period lengths are nearly equal to the corresponding values at 300 K. A detailed analysis of the phonon spectra showsmore » that this anomalous thermal conductivity behavior is a result of strong phonon wave interference. These observations indicate a promising strategy for manipulation of thermal transport in superlattices.« less

Annual Soil Temperature Wave at Four Depths in Southwestern Wisconsin

Treesearch

Richard S. Sartz

1967-01-01

Soil temperature was measured for a year on a southeast-facing slope of 25 percent, latitude 43 degrees 50 minutes N. The spring-summer cover was unmowed alfalfa-bluegrass meadow, the fall-winter cover, meadow stubble. Snow cover was light or absent. The soil was Fayette silt loam, valley phase. The annual temperature wave at all depths followed the air temperature...

Heat transfer, velocity-temperature correlation, and turbulent shear stress from Navier-Stokes computations of shock wave/turbulent boundary layer interaction flows

NASA Technical Reports Server (NTRS)

Wang, C. R.; Hingst, W. R.; Porro, A. R.

1991-01-01

The properties of 2-D shock wave/turbulent boundary layer interaction flows were calculated by using a compressible turbulent Navier-Stokes numerical computational code. Interaction flows caused by oblique shock wave impingement on the turbulent boundary layer flow were considered. The oblique shock waves were induced with shock generators at angles of attack less than 10 degs in supersonic flows. The surface temperatures were kept at near-adiabatic (ratio of wall static temperature to free stream total temperature) and cold wall (ratio of wall static temperature to free stream total temperature) conditions. The computational results were studied for the surface heat transfer, velocity temperature correlation, and turbulent shear stress in the interaction flow fields. Comparisons of the computational results with existing measurements indicated that (1) the surface heat transfer rates and surface pressures could be correlated with Holden's relationship, (2) the mean flow streamwise velocity components and static temperatures could be correlated with Crocco's relationship if flow separation did not occur, and (3) the Baldwin-Lomax turbulence model should be modified for turbulent shear stress computations in the interaction flows.

What Controls the Arctic Lower Stratosphere Temperature?

NASA Technical Reports Server (NTRS)

Newman, Paul A.; Nash, Eric R.; Einaudi, Franco (Technical Monitor)

2001-01-01

The temperature of the Arctic lower stratosphere is critical for understanding polar ozone levels. As temperatures drop below about 195 K, polar stratospheric clouds form, which then convert HCl and ClONO2 into reactive forms that are catalysts for ozone loss reactions. Hence, the lower stratospheric temperature during the March period is a key parameter for understanding polar ozone losses. The temperature is basically understood to be a result of planetary waves which drive the polar temperature away from a cold "radiative equilibrium" state. This is demonstrated using NCEP/NCAR reanalysis calculations of the heat flux and the mean polar temperature. The temperature during the March period is fundamentally driven by the integrated impact of large scale waves moving from the troposphere to the stratosphere during the January through February period. We will further show that the recent cold years in the northern polar vortex are a result of this weakened wave driving of the stratosphere.

Spatio-temporal variability of internal waves in the northern Gulf of Mexico studied with the Navy Coastal Ocean Model, NCOM

NASA Astrophysics Data System (ADS)

Cambazoglu, M. K.; Jacobs, G. A.; Howden, S. D.; Book, J. W.; Arnone, R.; Soto Ramos, I. M.; Vandermeulen, R. A.; Greer, A. T.; Miles, T. N.

2016-02-01

Internal waves enhance mixing in the upper ocean, transport nutrients and plankton over the water column and across the shelf from deeper waters to shallower coastal areas, and could also transport pollutants such as hydrocarbons onshore during an oil spill event. This study aims to characterize internal waves in the northern Gulf of Mexico (nGoM) and investigate the possible generation and dissipation mechanisms using a high-resolution (1-km) application of the Navy Coastal Ocean Model (NCOM). Three dimensional model products are used to detect the propagation patterns of internal waves. The vertical structure of internal waves is studied and the role of stratification is analyzed by looking at the temperature, salinity and velocity variations along the water column. The model predictions suggest the generation of internal waves on the continental shelf, therefore the role of ocean bottom topography interacting with tides and general circulation features such as the Loop Current Eddy front, on the internal wave generation will be discussed. The time periods of internal wave occurrences are identified from model predictions and compared to satellite ocean color imagery. Further data analysis, e.g. Fourier analysis, is implemented to determine internal wavelengths and frequencies and to determine if the response of internal waves are at tidal periods or at different frequencies. The atmospheric forcing provided to NCOM and meteorological data records are analyzed to define the interaction between wind forcing and internal wave generation. Wavelet analysis characterizes the ocean response to atmospheric events with periodic frequencies. Ocean color satellite imagery was used to visualize the location of the Mississippi river plume (and other oceanic features) and compared to the model predictions because the enhanced stratification from freshwater plumes which propagate across the Mississippi Bight can provide favorable conditions in coastal waters for internal wave generation and propagation. The findings of this study will provide insight about the internal wave dynamics in the Gulf of Mexico and their potential impact on the marine ecosystem.

Ion temperature effects on magnetotail Alfvén wave propagation and electron energization: ION TEMPERATURE EFFECTS ON ALFVÉN WAVES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Damiano, P. A.; Johnson, J. R.; Chaston, C. C.

2015-07-01

A new 2-D self-consistent hybrid gyrofluid-kinetic electron model in dipolar coordinates is presented and used to simulate dispersive-scale Alfvén wave pulse propagation from the equator to the ionosphere along an L = 10 magnetic field line. The model is an extension of the hybrid MHD-kinetic electron model that incorporates ion Larmor radius corrections via the kinetic fluid model of Cheng and Johnson (1999). It is found that consideration of a realistic ion to electron temperature ratio decreases the propagation time of the wave from the plasma sheet to the ionosphere by several seconds relative to a ρi=0 case (which alsomore » implies shorter timing for a substorm onset signal) and leads to significant dispersion of wave energy perpendicular to the ambient magnetic field. Additionally, ion temperature effects reduce the parallel current and electron energization all along the field line for the same magnitude perpendicular electric field perturbation.« less

Vertical temperature and density patterns in the Arctic mesosphere analyzed as gravity waves

NASA Technical Reports Server (NTRS)

Eberstein, I. J.; Theon, J. S.

1975-01-01

Rocket soundings conducted from high latitude sites in the Arctic mesosphere are described. Temperature and wind profiles and one density profile were observed independently to obtain the thermodynamic structure, the wind structure, and their interdependence in the mesosphere. Temperature profiles from all soundings were averaged, and a smooth curve (or series of smooth curves) drawn through the points. A hydrostatic atmosphere based on the average, measured temperature profile was computed, and deviations from the mean atmosphere were analyzed in terms of gravity wave theory. The vertical wavelengths of the deviations were 10-20 km, and the wave amplitudes slowly increased with height. The experimental data were matched by calculated gravity waves having a period of 15-20 minutes and a horizontal wavelength of 60-80 km. The wind measurements are consistent with the thermodynamic measurements. The results also suggest that gravity waves travel from East to West with a horizontal phase velocity of approximately 60 m sec-1.

Linear and nonlinear analysis of kinetic Alfven waves in quantum magneto-plasmas with arbitrary temperature degeneracy

NASA Astrophysics Data System (ADS)

Sadiq, Nauman; Ahmad, Mushtaq; Farooq, M.; Jan, Qasim

2018-06-01

Linear and nonlinear kinetic Alfven waves (KAWs) are studied in collisionless, non-relativistic two fluid quantum magneto-plasmas by considering arbitrary temperature degeneracy. A general coupling parameter is applied to discuss the range of validity of the proposed model in nearly degenerate and nearly non-degenerate plasma limits. Linear analysis of KAWs shows an increase (decrease) in frequency with the increase in parameter ζ ( δ ) for the nearly non-degenerate (nearly degenerate) plasma limit. The energy integral equation in the form of Sagdeev potential is obtained by using the approach of the Lorentz transformation. The analysis reveals that the amplitude of the Sagdeev potential curves and soliton structures remains the same, but the potential depth and width of soliton structure change for both the limiting cases. It is further observed that only density hump structures are formed in the sub-alfvenic region for value Kz 2 > 1 . The effects of parameters ζ, δ on the nonlinear properties of KAWs are shown in graphical plots. New results for comparison with earlier work have also been highlighted. The significance of this work to astrophysical plasmas is also emphasized.

Continuous two-wave lasing in microchip Nd : YAG lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ievlev, Ivan V; Koryukin, Igor' V; Lebedeva, Yu S

2011-08-31

Simultaneous two-wave lasing was obtained in microchip end-pumped Nd:YAG lasers at the wavelengths of 1061.5 and 1064.17 nm at room temperature. Laser wave intensities were studied as functions of crystal temperature and pump power. The ranges of parameters were determined in which the two-wave lasing occurs and the reasons for such lasing were established. A model is suggested, which adequately describes the experimental results obtained. (control of radiation parameters)

First ground-based observations of mesopause temperatures above the Eastern-Mediterranean Part II: OH*-climatology and gravity wave activity

NASA Astrophysics Data System (ADS)

Wüst, Sabine; Schmidt, Carsten; Bittner, Michael; Silber, Israel; Price, Colin; Yee, Jeng-Hwa; Mlynczak, Martin G.; Russell, James M.

2017-03-01

In this study, we present an analysis of approximately four years of nightly temperature data, acquired with the OH-spectrometer GRIPS 10 (GRound based Infrared P-branch Spectrometer), which was installed in Tel Aviv (32.11°N, 34.8°E), Israel in November 2011 for routine measurements. As our instrument does not give any height information, we use TIMED-SABER data in order to answer the question concerning the height region our measurement technique exactly addresses. For the first time, we estimate the density of wave potential energy for periods between some minutes and some hours for this station. These values are typical for gravity waves. Since GRIPS measurements do not currently provide vertically resolved data, the Brunt-Väisälä frequency, which is needed for the estimation of potential energy density, is calculated using TIMED-SABER measurements. The monthly mean density of wave potential energy is presented for periods shorter and longer than 60 min. For the winter months (November, December, and January), the data base allows the calculation of a seasonal mean for the different years. This publication is the companion paper to Silber et al. (2016). Here, we focus on oscillations with shorter periods.

Thermal responses in a coronal loop maintained by wave heating mechanisms

NASA Astrophysics Data System (ADS)

Matsumoto, Takuma

2018-05-01

A full 3-dimensional compressible magnetohydrodynamic (MHD) simulation is conducted to investigate the thermal responses of a coronal loop to the dynamic dissipation processes of MHD waves. When the foot points of the loop are randomly and continuously forced, the MHD waves become excited and propagate upward. Then, 1-MK temperature corona is produced naturally as the wave energy dissipates. The excited wave packets become non-linear just above the magnetic canopy, and the wave energy cascades into smaller spatial scales. Moreover, collisions between counter-propagating Alfvén wave packets increase the heating rate, resulting in impulsive temperature increases. Our model demonstrates that the heating events in the wave-heated loops can be nanoflare-like in the sense that they are spatially localized and temporally intermittent.

Frequency-agile THz-wave generation and detection system using nonlinear frequency conversion at room temperature.

PubMed

Guo, Ruixiang; Ikar'i, Tomofumi; Zhang, Jun; Minamide, Hiroaki; Ito, Hiromasa

2010-08-02

A surface-emitting THz parametric oscillator is set up to generate a narrow-linewidth, nanosecond pulsed THz-wave radiation. The THz-wave radiation is coherently detected using the frequency up-conversion in MgO: LiNbO(3) crystal. Fast frequency tuning and automatic achromatic THz-wave detection are achieved through a special optical design, including a variable-angle mirror and 1:1 telescope devices in the pump and THz-wave beams. We demonstrate a frequency-agile THz-wave parametric generation and THz-wave coherent detection system. This system can be used as a frequency-domain THz-wave spectrometer operated at room-temperature, and there are a high possible to develop into a real-time two-dimensional THz spectral imaging system.

International Conference on Infrared and Millimeter Waves, 18th, Univ. of Essex, Colchester, United Kingdom, Sept. 6-10, 1993, Conference Digest

NASA Astrophysics Data System (ADS)

Birch, James R.; Parker, Terence J.

Papers presented in these proceedings are grouped under the topics of FEL, detectors and sources, gas lasers, spectroscopy, windows for high-power applications, scattering, plasma diagnostics, waveguides, gyrotron, quasi-optical components, biological effects of IR and millimeter waves, and astronomical and atmospheric systems. Particular attention is given to the ENEA compact millimeter wave FEL, excitonic detectors of IR and submm waves, identification of submm CD2O lines, a two-frequency quasi-optical radiospectrometer for substance investigations, the effect of window tolerances on gyrotron performance, and analysis of scattering of the open resonator field from the cavity-backed aperture. Other papers are on submm laser interferometer-polarimeter for plasma diagnostics, the characteristics of the closed circular groove guide, a kW sixth-harmonic gyrofrequency multiplier, rugged FIR bandpass filters, millimeter waves and quantum medicines, and a horizontal atmospheric temperature sounder based on the 60-GHz oxygen absorptions.

Performance Enhancement of One and Two-Shaft Industrial Turboshaft Engines Topped With Wave Rotors

NASA Astrophysics Data System (ADS)

Fatsis, Antonios

2018-05-01

Wave rotors are rotating equipment designed to exchange energy between high and low enthalpy fluids by means of unsteady pressure waves. In turbomachinery, they can be used as topping devices to gas turbines aiming to improve performance. The integration of a wave rotor into a ground power unit is far more attractive than into an aeronautical application, since it is not accompanied by any inconvenience concerning the over-weight and extra dimensioning. Two are the most common types of ground industrial gas turbines: The one-shaft and the two-shaft engines. Cycle analysis for both types of gas turbine engines topped with a four-port wave rotor is calculated and their performance is compared to the performance of the baseline engine accordingly. It is concluded that important benefits are obtained in terms of specific work and specific fuel consumption, especially compared to baseline engines with low compressor pressure ratio and low turbine inlet temperature.

On the axisymmetric stability of heated supersonic round jets

PubMed Central

2016-01-01

We perform an inviscid, spatial stability analysis of supersonic, heated round jets with the mean properties assumed uniform on either side of the jet shear layer, modelled here via a cylindrical vortex sheet. Apart from the hydrodynamic Kelvin–Helmholtz (K–H) wave, the spatial growth rates of the acoustically coupled supersonic and subsonic instability waves are computed for axisymmetric conditions (m=0) to analyse their role on the jet stability, under increased heating and compressibility. With the ambient stationary, supersonic instability waves may exist for any jet Mach number Mj≥2, whereas the subsonic instability waves, in addition, require the core-to-ambient flow temperature ratio Tj/To>1. We show, for moderately heated jets at Tj/To>2, the acoustically coupled instability modes, once cut on, to govern the overall jet stability with the K–H wave having disappeared into the cluster of acoustic modes. Sufficiently high heating makes the subsonic modes dominate the jet near-field dynamics, whereas the supersonic instability modes form the primary Mach radiation at far field. PMID:27274691

Finite-element analysis of scattering parameters of surface acoustic wave bandpass filter formed on barium titanate thin film

NASA Astrophysics Data System (ADS)

Timoshenko; Kalinchuk; Shirokov

2018-04-01

The frequency dependence of scattering parameters of interdigital surface acoustic wave transducers placed on ferroelectric barium titanate (BaTiO3) epitaxial film in c-phase coated over magnesium oxide has been studied using the finite-element method (FEM) approach along with the perfectly matched layer (PML) technique. The interdigital transducer which has a comb-like structure with aluminum electrodes excites the mechanical wave. The distance between the fingers allows tuning the frequency properties of the wave propagation. The magnesium oxide is taken as the substrate. The two-dimensional model of two-port surface acoustic wave filter is created to calculate scattering parameters and to show how to design the fixture in COMSOLTM. Some practical computational challenges of finite element modeling of SAW devices in COMSOLTM are shown. The effect of lattice misfit strain on acoustic properties of heterostructures of BaTiO3 epitaxial film in c-phase at room temperature is discussed in present article for two low-frequency surface acoustic resonances.

Studies of the linear and nonlinear properties of Alfvén waves in LAPD

NASA Astrophysics Data System (ADS)

Carter, Troy; Dorfman, Seth; Gekelman, Walter; Tripathi, Shreekrishna; van Compernolle, Bart; Vincena, Steve; Rossi, Giovanni; Jenko, Frank

2015-11-01

An overview will be given of recent experimental research into linear and nonlinear properties of Alfvén waves in the Large Plasma Device (LAPD). The nonlinear three-wave interaction process at the heart of the parametric decay instability is studied by launching counter-propagating Alfvén waves from antennas placed at either end of LAPD, producing a damped ion acoustic mode. The decay of a lone, large amplitude Alfvén wave has been observed, producing co-propagating daughter waves with characteristics consistent with kinetic Alfvén waves. The process has an amplitude threshold and the frequency of the daughter modes varies with the amplitude of the pump. A new plasma source based on LaB6 cathode has been added to LAPD, enabling much higher density (x50), electron temperature (x2) and ion temperature (x6). This provides the opportunity to study the physics of waves and instabilities with space and astrophysically relevant β. Topics under investigation include the physics of Alfvén waves in increased β plasmas, electromagnetic effects in drift-Alfvén wave turbulence and the excitation of ion-temperature-anisotropy driven modes such as the mirror and firehose. Supported by NSF and DOE.

Cluster observations of band-limited Pc 1 waves associated with streaming H+ and O+ ions in the high-altitude plasma mantle

NASA Astrophysics Data System (ADS)

Engebretson, M. J.; Kahlstorf, C. R. G.; Murr, D. L.; Posch, J. L.; Keiling, A.; Lavraud, B.; Rème, H.; Lessard, M. R.; Kim, E.-H.; Johnson, J. R.; Dombeck, J.; Grison, B.; Robert, P.; Glassmeier, K.-H.; Décréau, P. M. E.

2012-10-01

Bursts of band-limited Pc 1 waves (0.2 to ˜1.0 Hz) with normalized frequency f/fH+ ˜ 0.5 have been observed by the Cluster spacecraft during many passes through the high-latitude plasma mantle. These transverse, left-hand polarized waves are associated with regions of H+ and O+ ions streaming away from Earth along magnetic field lines at the same velocity (˜140 km/s). Waves were observed only when H+ fluxes increased by factors of 10-1000 and energies of both ion species increased by factors of up to 10. We present two satellite-ground conjunctions to demonstrate the high latitude localization of these waves and their ability to reach the polar ionosphere and two extended examples of waves and associated ion distribution functions near the southern dusk flank magnetopause. We also present the results of a search for all such events during Cluster's 2002 and 2003 passages through the magnetotail, with orbital precession covering dawn to dusk on Earth's night side (June through December). A total of 46 events (band-limited Pc 1-2 waves accompanied by a sustained population of streaming H+ and O+ ions, separated by at least 12 min) were observed on 29 days. The waves were generally associated with intervals of southward IMF Bz and/or large IMF By (times of active cusp reconnection), and often but not always occurred during the main phase or early recovery phase of magnetic storms. Analysis of selected events shows that the waves are associated with large H+ temperature anisotropy, and that the waves propagate opposite to the direction of the streaming ions. A wave instability analysis using the WHAMP code confirms that the generation of these waves, via the ion cyclotron instability, is basically consistent with known physics. Their extended region of wave growth is likely, however, to reach tailward significantly beyond the Cluster orbit.

Hot weather in Potsdam in the years 1896-2015

NASA Astrophysics Data System (ADS)

Tomczyk, Arkadiusz M.

2018-02-01

The main objective of this article was the analysis of multiannual variability in the occurrence of hot days and heat waves in Potsdam in the last 120 years. The article used data concerning the maximum and minimum daily air temperature in Potsdam between 1896 and 2015, which were obtained from the Deutscher Wetterdienst database. A hot day was defined as a day with T max >30 °C, and a heat wave was considered a sequence of at least three hot days. The analysed multiannual period showed a statistically significant increase in T max in summer, which was 0.13 °C per 10 years. The observed increase in T max translated into an increase in the number of hot days and, consequently, in the frequency of the occurrence of heat waves. Within the analysed multiannual period, the lowest number of heat waves was recorded between 1896 and 1905, while the highest was observed between 2006 and 2015.

Hygrothermal wave propagation in viscoelastic graphene under in-plane magnetic field based on nonlocal strain gradient theory

NASA Astrophysics Data System (ADS)

Karami, Behrouz; Shahsavari, Davood; Li, Li

2018-03-01

A size-dependent model is developed for the hygrothermal wave propagation analysis of an embedded viscoelastic single layer graphene sheet (SLGS) under the influence of in-plane magnetic field. The bi-Helmholtz nonlocal strain gradient theory involving three small scale parameters is introduced to account for the size-dependent effects. The size-dependent model is deduced based on Hamilton's principle. The closed-form solution of eigenfrequency relation between wave number and phase velocity is achieved. By studying the size-dependent effects on the flexural wave of SLGS, the dispersion relation predicted by the developed size-dependent model can show a good match with experimental data. The influence of in-plane magnetic field, temperature and moisture of environs, structural damping, damped substrate, lower and higher order nonlocal parameters and the material characteristic parameter on the phase velocity of SLGS is explored.

Electrodynamics in cylindrical symmetry in the magnetic plasma state

NASA Astrophysics Data System (ADS)

López-Bara, F. I.; López-Aguilar, F.

2018-05-01

Excited states in magnetic structures of the so-called spin-ices and in some artificial magnetic materials present a behaviour as being a magnetic neutral plasma. In this state the electromagnetic waves in confined systems (waveguides) filled with materials with magnetic charges are able to transmit information and energy. In the natural spin-ices, the difficulty is the very low temperature for which these magnetic entities appear, whose phenomenology under the electromagnetic interaction is that of solids containing magnetic charges. However, similar behaviour may be present in other compounds at higher temperatures, even at room temperature and they are named artificial spin-ice compounds. This analysis is addressed to obtain theoretical results about magnetic responses and frequency-dependent magnetricity. The key physical magnitudes are the plasmon frequency () which is related to the cut-off frequency in a wave guide and the effective inertial masses () of these magnetic charges. All properties of the electromagnetic propagation in these compounds with effective magnetic monopoles depend on and m. This is carried out including the dissipative forces among magnetic charges which give new characteristic features to the electromagnetic propagation. The main goal of this work is the analysis of these electromagnetic properties in order to find possible circuital applications of these materials to be utilized by devices.

Sensitivity of Middle Atmospheric Temperature and Circulation in the UIUC Mesosphere-Stratosphere-Troposphere GCM to the Treatment of Subgrid-Scale Gravity-Wave Breaking

NASA Technical Reports Server (NTRS)

Yang, Fanglin; Schlesinger, Michael E.; Andranova, Natasha; Zubov, Vladimir A.; Rozanov, Eugene V.; Callis, Lin B.

2003-01-01

The sensitivity of the middle atmospheric temperature and circulation to the treatment of mean- flow forcing due to breaking gravity waves was investigated using the University of Illinois at Urbana-Champaign 40-layer Mesosphere-Stratosphere-Troposphere General Circulation Model (MST-GCM). Three GCM experiments were performed. The gravity-wave forcing was represented first by Rayleigh friction, and then by the Alexander and Dunkerton (AD) parameterization with weak and strong breaking effects of gravity waves. In all experiments, the Palmer et al. parameterization was included to treat the breaking of topographic gravity waves in the troposphere and lower stratosphere. Overall, the experiment with the strong breaking effect simulates best the middle atmospheric temperature and circulation. With Rayleigh friction and the weak breaking effect, a large warm bias of up to 60 C was found in the summer upper mesosphere and lower thermosphere. This warm bias was linked to the inability of the GCM to simulate the reversal of the zonal winds from easterly to westerly crossing the mesopause in the summer hemisphere. With the strong breaking effect, the GCM was able to simulate this reversal, and essentially eliminated the warm bias. This improvement was the result of a much stronger meridional transport circulation that possesses a strong vertical ascending branch in the summer upper mesosphere, and hence large adiabatic cooling. Budget analysis indicates that 'in the middle atmosphere the forces that act to maintain a steady zonal-mean zonal wind are primarily those associated with the meridional transport circulation and breaking gravity waves. Contributions from the interaction of the model-resolved eddies with the mean flow are small. To obtain a transport circulation in the mesosphere of the UIUC MST-GCM that is strong enough to produce the observed cold summer mesopause, gravity-wave forcing larger than 100 m/s/day in magnitude is required near the summer mesopause. In the tropics, only with the AD parameterization can the model produce realistic semiannual oscillations.

Observation of spin waves in Pd(1. 5% Fe). Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lynn, J.W.; Rhyne, J.J.; Budnick, J.I.

1982-01-01

Inelastic neutron scattering measurements have been carried out on the giant-moment alloy system Pd(1.5% Fe), which is in the dilute ferromagnetic regime. Below the Curie temperature of 67K, relatively well-defined spin-wave excitations have been observed in the small wavevector region (Q < 0.14/A). The dispersion of these excitations is consistent with the quadratic relation E = D(Q/sup 2/) expected for an isotropic ferromagnet, with D = 40 meV-(A/sup 2/) at a temperature of the 40K. With increasing temperature, the spin waves are found to renormalize in energy, and broaden rapidly both with increasing Q and increasing temperature.

REFLECTION OF PROPAGATING SLOW MAGNETO-ACOUSTIC WAVES IN HOT CORONAL LOOPS: MULTI-INSTRUMENT OBSERVATIONS AND NUMERICAL MODELING

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mandal, Sudip; Banerjee, Dipankar; Pant, Vaibhav

Slow MHD waves are important tools for understanding coronal structures and dynamics. In this paper, we report a number of observations from the X-Ray Telescope (XRT) on board HINODE and Solar Dynamic Observatory /Atmospheric Imaging Assembly (AIA) of reflecting longitudinal waves in hot coronal loops. To our knowledge, this is the first report of this kind as seen from the XRT and simultaneously with the AIA. The wave appears after a micro-flare occurs at one of the footpoints. We estimate the density and temperature of the loop plasma by performing differential emission measure (DEM) analysis on the AIA image sequence.more » The estimated speed of propagation is comparable to or lower than the local sound speed, suggesting it to be a propagating slow wave. The intensity perturbation amplitude, in every case, falls very rapidly as the perturbation moves along the loop and eventually vanishes after one or more reflections. To check the consistency of such reflection signatures with the obtained loop parameters, we perform a 2.5D MHD simulation, which uses the parameters obtained from our observation as inputs, and perform forward modeling to synthesize AIA 94 Å images. Analyzing the synthesized images, we obtain the same properties of the observables as for the real observation. From the analysis we conclude that a footpoint heating can generate a slow wave which then reflects back and forth in the coronal loop before fading. Our analysis of the simulated data shows that the main agent for this damping is anisotropic thermal conduction.« less

Piezoelectric shear wave resonator and method of making same

DOEpatents

Wang, Jin S.; Lakin, Kenneth M.; Landin, Allen R.

1988-01-01

An acoustic shear wave resonator comprising a piezoelectric film having its C-axis substantially inclined from the film normal such that the shear wave coupling coefficient significantly exceeds the longitudinal wave coupling coefficient, whereby the film is capable of shear wave resonance, and means for exciting said film to resonate. The film is prepared by deposition in a dc planar magnetron sputtering system to which a supplemental electric field is applied. The resonator structure may also include a semiconductor material having a positive temperature coefficient of resonance such that the resonator has a temperature coefficient of resonance approaching 0 ppm/.degree.C.

Method of making a piezoelectric shear wave resonator

DOEpatents

Wang, Jin S.; Lakin, Kenneth M.; Landin, Allen R.

1987-02-03

An acoustic shear wave resonator comprising a piezoelectric film having its C-axis substantially inclined from the film normal such that the shear wave coupling coefficient significantly exceeds the longitudinal wave coupling coefficient, whereby the film is capable of shear wave resonance, and means for exciting said film to resonate. The film is prepared by deposition in a dc planar magnetron sputtering system to which a supplemental electric field is applied. The resonator structure may also include a semiconductor material having a positive temperature coefficient of resonance such that the resonator has a temperature coefficient of resonance approaching 0 ppm/.degree.C.

High Temperature Shear Horizontal Electromagnetic Acoustic Transducer for Guided Wave Inspection

PubMed Central

Kogia, Maria; Gan, Tat-Hean; Balachandran, Wamadeva; Livadas, Makis; Kappatos, Vassilios; Szabo, Istvan; Mohimi, Abbas; Round, Andrew

2016-01-01

Guided Wave Testing (GWT) using novel Electromagnetic Acoustic Transducers (EMATs) is proposed for the inspection of large structures operating at high temperatures. To date, high temperature EMATs have been developed only for thickness measurements and they are not suitable for GWT. A pair of water-cooled EMATs capable of exciting and receiving Shear Horizontal (SH0) waves for GWT with optimal high temperature properties (up to 500 °C) has been developed. Thermal and Computational Fluid Dynamic (CFD) simulations of the EMAT design have been performed and experimentally validated. The optimal thermal EMAT design, material selection and operating conditions were calculated. The EMAT was successfully tested regarding its thermal and GWT performance from ambient temperature to 500 °C. PMID:27110792

Generation of Highly Oblique Lower Band Chorus Via Nonlinear Three-Wave Resonance

DOE PAGES

Fu, Xiangrong; Gary, Stephen Peter; Reeves, Geoffrey D.; ...

2017-09-05

Chorus in the inner magnetosphere has been observed frequently at geomagnetically active times, typically exhibiting a two-band structure with a quasi-parallel lower band and an upper band with a broad range of wave normal angles. But recent observations by Van Allen Probes confirm another type of lower band chorus, which has a large wave normal angle close to the resonance cone angle. It has been proposed that these waves could be generated by a low-energy beam-like electron component or by temperature anisotropy of keV electrons in the presence of a low-energy plateau-like electron component. This paper, however, presents an alternativemore » mechanism for generation of this highly oblique lower band chorus. Through a nonlinear three-wave resonance, a quasi-parallel lower band chorus wave can interact with a mildly oblique upper band chorus wave, producing a highly oblique quasi-electrostatic lower band chorus wave. This theoretical analysis is confirmed by 2-D electromagnetic particle-in-cell simulations. Furthermore, as the newly generated waves propagate away from the equator, their wave normal angle can further increase and they are able to scatter low-energy electrons to form a plateau-like structure in the parallel velocity distribution. As a result, the three-wave resonance mechanism may also explain the generation of quasi-parallel upper band chorus which has also been observed in the magnetosphere.« less

Classical Heat-Flux Measurements in Coronal Plasmas from Collective Thomson-Scattering Spectra

NASA Astrophysics Data System (ADS)

Henchen, R. J.; Hu, S. X.; Katz, J.; Froula, D. H.; Rozmus, W.

2016-10-01

Collective Thomson scattering was used to measure heat flux in coronal plasmas. The relative amplitude of the Thomson-scattered power into the up- and downshifted electron plasma wave features was used to determine the flux of electrons moving along the temperature gradient at three to four times the electron thermal velocity. Simultaneously, the ion-acoustic wave features were measured. Their relative amplitude was used to measure the flux of the return-current electrons. The frequencies of these ion-acoustic and electron plasma wave features provide local measurements of the electron temperature and density. These spectra were obtained at five locations along the temperature gradient in a laser-produced blowoff plasma. These measurements of plasma parameters are used to infer the Spitzer-Härm flux (qSH = - κ∇Te ) and are in good agreement with the values of the heat flux measured from the scattering-feature asymmetries. Additional experiments probed plasma waves perpendicular to the temperature gradient. The data show small effects resulting from heat flux compared to probing waves along the temperature gradient. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

Marginal sea surface temperature variation as a pre-cursor of heat waves over the Korean Peninsula

NASA Astrophysics Data System (ADS)

Ham, Yoo-Geun; Na, Hye-Yun

2017-11-01

This study examines the role of the marginal sea surface temperature (SST) on heat waves over Korea. It is found that sea surface warming in the south sea of Korea/Japan (122-138°E, 24- 33°N) causes heat waves after about a week. Due to the frictional force, the positive geopotential height anomalies associated with the south sea warming induce divergent flows over the boundary layer. This divergent flow induces the southerly in Korea, which leads to a positive temperature advection. On the other hand, over the freeatmosphere, the geostrophic wind around high-pressure anomalies flows in a westerly direction over Korea during the south sea warming, which is not effective in temperature advection. Therefore, the positive temperature advection in Korea due to the south sea warming decreases with height. This reduces the vertical potential temperature gradient, which indicates a negative potential vorticity (PV) tendency over Korea. Therefore, the high-pressure anomaly over the south sea of Korea is propagated northward, which results in heat waves due to more incoming solar radiation.

Mountain Wave Analysis Using Fourier Methods

DTIC Science & Technology

2007-10-01

model for altitudes up to 18 km for the same location using the Hilo , Hawaii 1200 UTC rawinsonde for the background velocity and temperature profile... Hawaii terrain and atmosphere 46 for 12 Dec 2002 vii Tables 1...20 3. Three-Layer Model Specifications for Hawaii 12 December 2002 06 UTC 22 4. Three-Layer Model

Mesospheric OH layer altitude at midlatitudes: variability over the Sierra Nevada Observatory in Granada, Spain (37° N, 3° W)

NASA Astrophysics Data System (ADS)

García-Comas, Maya; José López-González, María; González-Galindo, Francisco; de la Rosa, José Luis; López-Puertas, Manuel; Shepherd, Marianna G.; Shepherd, Gordon G.

2017-10-01

The mesospheric OH layer varies on several timescales, primarily driven by variations in atomic oxygen, temperature, density and transport (advection). Vibrationally excited OH airglow intensity, rotational temperature and altitude are closely interrelated and thus accompany each other through these changes. A correct interpretation of the OH layer variability from airglow measurements requires the study of the three variables simultaneously. Ground-based instruments measure excited OH intensities and temperatures with high temporal resolution, but they do not generally observe altitude directly. Information on the layer height is crucial in order to identify the sources of its variability and the causes of discrepancies in measurements and models. We have used SABER space-based 2002-2015 data to infer an empirical function for predicting the altitude of the layer at midlatitudes from ground-based measurements of OH intensity and rotational temperature. In the course of the analysis, we found that the SABER altitude (weighted by the OH volume emission rate) at midlatitudes decreases at a rate of 40 m decade-1, accompanying an increase of 0.7 % decade-1 in OH intensity and a decrease of 0.6 K decade-1 in OH equivalent temperature. SABER OH altitude barely changes with the solar cycle, whereas OH intensity and temperature vary by 7.8 % per 100 s.f.u. and 3.9 K per 100 s.f.u., respectively. For application of the empirical function to Sierra Nevada Observatory SATI data, we have calculated OH intensity and temperature SATI-to-SABER transfer functions, which point to relative instrumental drifts of -1.3 % yr-1 and 0.8 K yr-1, respectively, and a temperature bias of 5.6 K. The SATI predicted altitude using the empirical function shows significant short-term variability caused by overlapping waves, which often produce changes of more than 3-4 km in a few hours, going along with 100 % and 40 K changes in intensity and temperature, respectively. SATI OH layer wave effects are smallest in summer and largest around New Year's Day. Moreover, those waves vary significantly from day to day. Our estimations suggest that peak-to-peak OH nocturnal variability, mainly due to wave variability, changes within 60 days at least 0.8 km for altitude in autumn, 45 % for intensity in early winter and 6 K for temperature in midwinter. Plausible upper limit ranges of those variabilities are 0.3-0.9 km, 40-55 % and 4-7 K, with the exact values depending on the season.

Analysis of the normal-state magnetic susceptibility of La sub 2 minus x Sr sub x CuO sub 4+ y (abstract) (US)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Filipkowski, M.E.; Budnick, J.I.

1991-11-15

We describe a quantitative analysis of the low-temperature ({ital T}{lt}300 K) susceptibility ({chi}({ital T})) of La{sub 2{minus}x}Sr{sub x}CuO{sub 4+y} for dopant concentrations in the vicinity of the superconducting phase boundary (SPB) at {ital x}=0.055. This analysis is based on a phenomenological model for the temperature dependence consisting of a Curie-like 1/{ital T} term plus a term linear in {ital T}. We find that the former exhibits nontrivial doping dependence at the SPB, while the {ital T}-linear part accepts decomposition into a Pauli contribution and a portion which can be understood using spin-wave theory.

Internal Waves in CVX

NASA Technical Reports Server (NTRS)

Berg, Robert F.

1996-01-01

Near the liquid-vapor critical point, density stratification supports internal gravity waves which affect 1-g viscosity measurements in the CVX (Critical Viscosity of Xenon) experiment. Two internal-wave modes were seen in the horizontal viscometer. The frequencies of the two modes had different temperature dependences: with decreasing temperature, the higher frequency increased monotonically from 0.7 to 2.8 Hz, but the lower frequency varied non-monotonically, with a maximum of 1.0 Hz at 20 mK above the critical temperature. The measured frequencies agree with independently calculated frequencies to within 15%.

Electrically-Active Convection in Tropical Easterly Waves and Implications for Tropical Cyclogenesis in the Atlantic and East Pacific

NASA Technical Reports Server (NTRS)

Leppert, Kenneth D., II; Petersen, Walter A.; Cecil, Daniel J.

2012-01-01

In this study, we investigate the characteristics of tropical easterly wave convection and the possible implications of convective structure on tropical cyclogenesis and intensification over the Atlantic Ocean and East Pacific using data from the Tropical Rainfall Measurement Mission Microwave Imager, Precipitation Radar (PR), and Lightning Imaging Sensor as well as infrared (IR) brightness temperature data from the NASA global-merged IR brightness temperature dataset. Easterly waves were partitioned into northerly, southerly, trough, and ridge phases based on the 700-hPa meridional wind from the NCEP-NCAR reanalysis dataset. Waves were subsequently divided according to whether they did or did not develop tropical cyclones (i.e., developing and nondeveloping, respectively), and developing waves were further subdivided according to development location. Finally, composites as a function of wave phase and category were created using the various datasets. Results suggest that the convective characteristics that best distinguish developing from nondeveloping waves vary according to where developing waves spawn tropical cyclones. For waves that developed a cyclone in the Atlantic basin, coverage by IR brightness temperatures .240 K and .210 K provide the best distinction between developing and nondeveloping waves. In contrast, several variables provide a significant distinction between nondeveloping waves and waves that develop cyclones over the East Pacific as these waves near their genesis location including IR threshold coverage, lightning flash rates, and low-level (<4.5 km) PR reflectivity. Results of this study may be used to help develop thresholds to better distinguish developing from nondeveloping waves and serve as another aid for tropical cyclogenesis forecasting.

Thermal and ghost reflection modeling for a 180-deg. field-of-view long-wave infrared lens

NASA Astrophysics Data System (ADS)

Shi, Weimin; Couture, Michael E.

2001-03-01

Optics 1, Inc. has successfully designed and developed a 180 degree(s) field of view long wave infrared lens for USAF/AFRL under SBIR phase I and II funded projects in support of the multi-national Programmable Integrated Ordinance Suite (PIOS) program. In this paper, a procedure is presented on how to evaluate image degradation caused by asymmetric aerodynamic dome heating. In addition, a thermal gradient model is proposed to evaluate degradation caused by axial temperature gradient throughout the entire PIOS lens. Finally, a ghost reflection analysis is demonstrated with non-sequential model.

Evanescent wave sensing and absorption analysis of herbal tea floral extracts in the presence of silver metal complexes

NASA Astrophysics Data System (ADS)

Priyamvada, V. C.; Radhakrishnan, P.

2017-06-01

Fiber optic evanescent wave sensors are used for studying the absorption properties of biochemical samples. The studies give precise information regarding the actual ingredients of the samples. Recent studies report the corrosion of silver in the presence glucose dissolved in water and heated to a temperature of 70°C. Based on this report evanescent absorption studies are carried out in hibiscus herbal tea floral extracts in the presence of silver metal complexes. These studies can also lead to the evaluation of the purity of the herbal tea extract.

DOE Office of Scientific and Technical Information (OSTI.GOV)

EL-Shamy, E. F., E-mail: emadel-shamy@hotmail.com; Department of Physics, College of Science, King Khalid University, P.O. 9004, Abha; Al-Asbali, A. M., E-mail: aliaa-ma@hotmail.com

A theoretical investigation is carried out to study the propagation and the head-on collision of dust-acoustic (DA) shock waves in a strongly coupled dusty plasma consisting of negative dust fluid, Maxwellian distributed electrons and ions. Applying the extended Poincaré–Lighthill–Kuo method, a couple of Korteweg–deVries–Burgers equations for describing DA shock waves are derived. This study is a first attempt to deduce the analytical phase shifts of DA shock waves after collision. The impacts of physical parameters such as the kinematic viscosity, the unperturbed electron-to-dust density ratio, parameter determining the effect of polarization force, the ion-to-electron temperature ratio, and the effective dustmore » temperature-to-ion temperature ratio on the structure and the collision of DA shock waves are examined. In addition, the results reveal the increase of the strength and the steepness of DA shock waves as the above mentioned parameters increase, which in turn leads to the increase of the phase shifts of DA shock waves after collision. The present model may be useful to describe the structure and the collision of DA shock waves in space and laboratory dusty plasmas.« less

Investigating the thermally induced acoustoelastic effect in isotropic media with Lamb waves

PubMed Central

Dodson, Jacob C.; Inman, Daniel J.

2014-01-01

Elastic wave velocities in metallic structures are affected by variations in environmental conditions such as changing temperature. This paper extends the theory of acoustoelasticity by allowing thermally induced strains in unconstrained isotropic media, and it experimentally examines the velocity variation of Lamb waves in aluminum plates (AL-6061) due to isothermal temperature deviations. This paper presents both thermally induced acoustoelastic constants and thermally varying effective Young's modulus and Poisson's ratio which include the third order elastic material constants. The experimental thermal sensitivity of the phase velocity (∂vP/∂θ) for both the symmetric and antisymmetric modes are bounded by two theories, the acoustoelastic Lamb wave theory with thermo-acoustoelastic tensors and the thermoelastic Lamb wave theory using an effective thermo-acoustoelastic moduli. This paper shows the theoretical thermally induced acoustoelastic Lamb wave thermal sensitivity (∂vP/∂θ) is an upper bound approximation of the experimental thermal changes, but the acoustoelastic Lamb wave theory is not valid for predicting the antisymmetric (A0) phase velocity at low frequency-thickness values, <1.55 MHz mm for various temperatures. PMID:25373955

Comparative study of DPAL and XPAL systems and selection principal of parameters

NASA Astrophysics Data System (ADS)

Huang, Wei; Tan, Rongqing; Li, Zhiyong; Han, Gaoce; Li, Hui

2016-10-01

A theoretical model based on common pump structure is proposed to analyze the laser output characteristics of DPAL (Diode pumped alkali vapor laser) and XPAL (Exciplex pumped alkali laser) in this paper. The model predicts that an optical-to-optical efficiency approaching 80% can be achieved for continuous-wave four- and five-XPAL systems with broadband pumping which is several times of pumped linewidth for DPAL. Operation parameters including pumped intensity, temperature, cell' s length, mixed gas concentration, pumped linewidth and output mirror reflectivity are analyzed for DPAL and XPAL systems basing on the kinetic model. The result shows a better performance in Cs-Ar XPAL laser with requirements of relatively high Ar concentration, high pumped intensity and high temperature. Comparatively, for Cs-DPAL laser, lower temperature and lower pumped intensity should be acquired. In addition, the predictions of selection principal of temperature and cell's length are also presented. The conception of the equivalent "alkali areal density" is proposed in this paper. It is defined as the product of the alkali density and cell's length. The result shows that the output characteristics of DPAL (or XPAL) system with the same alkali areal density but different temperatures turn out to be equal. It is the areal density that reflects the potential of DPAL or XPAL systems directly. A more detailed analysis of similar influences of cavity parameters with the same areal density is also presented. The detailed results of continuous-wave DPAL and XPAL performances as a function of pumped laser linewidth and mixed gas pressure are presented along with an analysis of influences of output coupler.

Numerical analysis on interactions of vortex, shock wave, and exothermal reaction in a supersonic planar shear layer laden with droplets

NASA Astrophysics Data System (ADS)

Ren, Zhaoxin; Wang, Bing; Zheng, Longxi

2018-03-01

The analysis on the interactions of a large-scale shearing vortex, an incident oblique shock wave, and a chemical reaction in a planar shear layer is performed by numerical simulations. The reacting flows are obtained by directly solving the multi-species Navier-Stokes equations in the Eulerian frame, and the motions of individual point-mass fuel droplets are tracked in the Lagrangian frame considering the two-way coupling. The influences of shock strength and spray equivalence ratio on the shock-vortex interaction and the induced combustion are further studied. Under the present conditions, the incident shock is distorted by the vortex evolution to form the complicated waves including an incident shock wave, a multi-refracted wave, a reflected wave, and a transmitted wave. The local pressure and temperature are elevated by the shock impingement on the shearing vortex, which carries flammable mixtures. The chemical reaction is mostly accelerated by the refracted shock across the vortex. Two different exothermal reaction modes could be distinguished during the shock-vortex interaction as a thermal mode, due to the additional energy from the incident shock, and a local quasi detonation mode, due to the coupling of the refracted wave with reaction. The former mode detaches the flame and shock wave, whereas the latter mode tends to occur when the incident shock strength is higher and local equivalence ratio is higher approaching to the stoichiometric value. The numerical results illustrate that those two modes by shock-vortex interaction depend on the structure of the post-shock flame kernel, which may be located either in the vortex-braids of post-shock flows or in the shock-vortex interaction regime.

Thermal analysis of electron gun for travelling wave tubes

NASA Astrophysics Data System (ADS)

Bhat, K. S.; Sreedevi, K.; Ravi, M.

2006-11-01

Thermal analysis of a pierce type electron gun using the FEM software ANSYS and its experimental validation are presented in this paper. Thermal analysis of the electron gun structure has been carried out to find out the effect of heater power on steady state temperature and warm-up time. The thermal drain of the supporting structure has also been analyzed for different materials. These results were experimentally verified in an electron gun. The experimental results closely match the ANSYS results.

Assessing climate change over the Marche Region (central Italy) from 1961 to 2100: projected changes in mean temperature and future heat waves characterization (with a statistical evaluation of RCMs local performance)

NASA Astrophysics Data System (ADS)

Sangelantoni, Lorenzo; Coluccelli, Alessandro; Russo, Aniello

2014-05-01

Marche region (central Italy, facing the Adriatic Sea) climate dynamics are connected to the Mediterranean basin, identified as one of the most sensitive areas to ongoing climate change. Taken into account difficulties to carry out an overarching assessment over the heterogeneous Mediterranean climate-change issues frame, we opted toward a consistent regional bordered study. Projected changes in mean seasonal temperature, with an introductory multi-statistical model performance evaluation and a future heat waves intensity and duration characterization, are here presented. Multi-model projections over Marche Region, on daily mean, minimum and maximum temperature, have been extracted from the outputs of a set of 7 Regional Climate Models (RCMs) over Europe run by several research Institutes participating to the EU ENSEMBLE project. These climate simulations from 1961 to 2100 refer to the boundary conditions of the IPCC A1B emission scenario, and have a horizontal resolution of 25km × 25km. Furthermore, two RCMs outputs from Med-CORDEX project, with a higher horizontal resolution (12km x 12km) and boundary conditions provided by the new Representative Concentration Pathway (RCP) 4.5 and 8.5, are considered. Observed daily mean, minimum and maximum temperature over Marche region domain have been extracted from E-OBS gridded data set (Version 9.0) referring to the period 1970-2004. This twofold work firstly provides a concise statistical summary of how well employed RCMs reproduce observed (1970-2004) mean temperature over Marche region in term of correlation, root-mean-square difference, and ratio of their variances, graphically displayed on a 2D-Taylor diagram. This multi-statistical model performance evaluation easily allows: - to compare the agreement with observation of the 9 individual RCMs - to compare RCMs with different horizontal resolution (12 km and 25 km) - to evaluate the improvement provided by the RCMs ensemble. Results indicate that the 9 RCMs ensemble provides the statistically best reproduction of the observed interannual mean temperature distribution. Secondly, we assessed projected seasonal ensemble average change in mean temperature referring to the ending 21st century obtained by comparison between 2071-2100 and 1961-1990 time slice modeled mean value over Marche region. Results emphasize summer as the season most affected by projected temperature increase (+4.5°C / +5.0°C), followed by spring season temperature increase (+3.5°C / +4.0°C). Finally, considering that some of the most severe health hazards arise from multi-day heat-waves, associated with both hot day-time and warm night-time temperatures, we assessed modeled trend (1961-2100) of the heat waves intensity and duration: intensity through the temporal evolution of the summer (J J A months) maximum and minimum temperature 90th percentile, heat waves length by temporal evolution of two detected threshold-based indices (annual maximum number of consecutive days characterized by Tmin >= 24°C and annual maximum number of consecutive days characterized by Tmax > = 32°C). Same analysis for both coastal and mountainous areas has been conducted. Future research plans aim to involve ensemble RCMs simulation, processed with bias correction methods, in forcing climate change impacts models, to provide a detailed regional heat waves impacts scenario, mainly over agriculture and health sectors.

Modeling Study of Mesospheric Planetary Waves: Genesis and Characteristics

NASA Technical Reports Server (NTRS)

Mayr, H. G.; Mengel, J. G.; Talaat, E. L.; Porter, H. S.; Chan, K. L.

2003-01-01

In preparation for the measurements from the TIMED mission and coordinated ground based observations, we discuss results for the planetary waves (PWs) that appear in our Numerical Spectral Model (NSM). The present model accounts for a tropospheric heat source in the zonal mean (m = 0), which reproduces qualitatively the observed zonal jets near the tropopause and the accompanying reversal in the latitudinal temperature variations. We discuss the PWs that are solely generated internally, i.e., without the explicit excitation sources related to tropospheric convection or topography. Our analysis shows that PWs are not produced when the zonally averaged heat source into the atmosphere is artificially suppressed, and that the PWs generally are significantly weaker when the tropospheric source is not applied. Instabilities associated with the zonal mean temperature, pressure and wind fields, which still need to be explored, are exciting PWs that have amplitudes in the mesosphere comparable to those observed. Three classes of PWs are generated in the NSM. (1) Rossby waves, (2) Rossby gravity waves propagating westward at low latitudes, and (3) Eastward propagating equatorial Kelvin waves. A survey of the PWs reveals that the largest wind amplitudes tend to occur below 80 km in the winter hemisphere, but above that altitude they occur in the summer hemisphere where the amplitudes can approach 50 meters per second. It is shown that the non-migrating tides in the mesosphere, generated by non-linear coupling between migrating tides and PWs, are significantly larger for the model with the tropospheric heat source.

Description of data on the Nimbus 7 LIMS map archive tape: Temperature and geopotential height

NASA Technical Reports Server (NTRS)

Haggard, K. V.; Remsberg, E. E.; Grose, W. L.; Russell, J. M., III; Marshall, B. T.; Lingenfelser, G.

1986-01-01

The process by which the analysis of the Limb Infared Monitor of the Stratosphere (LIMS) experiment data were used to produce estimates of synoptic maps of temperature and geopotential height is described. In addition to a detailed description of the analysis procedure, several interesting features in the data are discussed and these features are used to demonstrate how the analysis procedure produced the final maps and how one can estimate the uncertainties in the maps. In addition, features in the analysis are noted that would influence how one might use, or interpret, the results. These include subjects such as smoothing and the interpretation of wave components. While some suggestions are made for an improved analysis of the data, it is shown that, in general, the maps are an excellent estimation of the synoptic fields.

Observations of wave-particle interactions in the flux pile-up region of asymmetric reconnection

NASA Astrophysics Data System (ADS)

Argall, M. R.; Paulson, K. W.; Ahmadi, N.; Matsui, H.; Torbert, R. B.; Alm, L.; Le Contel, O.; Khotyaintsev, Y. V.; Wilder, F. D.; Turner, D. L.; Strangeway, R. J.; Schwartz, S. J.; Magnes, W.; Giles, B. L.; Lindqvist, P. A.; Ergun, R.; Mauk, B.; Leonard, T. W.

2017-12-01

Recent observations have shown electron energization to >100keV with simultaneous whistler wave activity in the vicinity of the dayside reconnection site. We investigate one possible mechanism for producing these energetic particles. Counter-streaming electrons from the magnetosphere enter the diffusion region and are scattered to all pitch angles (PAs) by strong field-line curvature. As the electrons flow outward into the exhaust, they remagnetize and are focused toward 90° at mirror points within the flux pile-up region. This effect, combined with heating mechanisms in the EDR, produces a temperature anisotropy, while the weak magnetic field lowers the resonant energy into the bulk energy of the plasma. In the end, whistler waves are produced near 100Hz with a wave normal angle of 20°. Simultaneous with the waves, the Electron Drift Instrument observes particle flux modulations of 0° and 180° PA, 500 eV electrons. Multi-spacecraft analysis and Liouville mapping techniques allow us to determine the parallel wave current, potential, and associated energy dissipation. Bursts of 100keV electrons are observed and may interact with the whistler waves.

Three dimensional dust-acoustic solitary waves in an electron depleted dusty plasma with two-superthermal ion-temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Borhanian, J.; Shahmansouri, M.

2013-01-15

A theoretical investigation is carried out to study the existence and characteristics of propagation of dust-acoustic (DA) waves in an electron-depleted dusty plasma with two-temperature ions, which are modeled by kappa distribution functions. A three-dimensional cylindrical Kadomtsev-Petviashvili equation governing evolution of small but finite amplitude DA waves is derived by means of a reductive perturbation method. The influence of physical parameters on solitary wave structure is examined. Furthermore, the energy integral equation is used to study the existence domains of the localized structures. It is found that the present model can be employed to describe the existence of positive asmore » well as negative polarity DA solitary waves by selecting special values for parameters of the system, e.g., superthermal index of cold and/or hot ions, cold to hot ion density ratio, and hot to cold ion temperature ratio. This model may be useful to understand the excitation of nonlinear DA waves in astrophysical objects.« less

The Effect of Internal Gravity Waves on Fluctuations in Meteorological Parameters of the Atmospheric Boundary Layer

NASA Astrophysics Data System (ADS)

Zaitseva, D. V.; Kallistratova, M. A.; Lyulyukin, V. S.; Kouznetsov, R. D.; Kuznetsov, D. D.

2018-03-01

Variations in the intensity of turbulence during wave activity in the stable atmospheric boundary layer over a homogeneous steppe surface have been analyzed. Eight wave activity episodes recorded with a Doppler sodar in August 2015 at the Tsimlyansk Scientific Station of the Obukhov Institute of Atmospheric Physics have been studied. These episodes include seven trains of Kelvin-Helmholtz waves and one train of buoyancy waves. Variations in the rms deviation of the vertical wind-velocity component, the temperature structure parameter, and vertical heat and momentum fluxes have been estimated for each episode of wave activity. It has been found that Kelvin-Helmholtz waves slightly affect the intensity of turbulence, while buoyancy waves cause the temperature structure parameter and the vertical fluxes to increase by more than an order of magnitude.

Kink Waves in Non-isothermal Stratified Solar Waveguides: Effect of the External Magnetic Field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lopin, I.; Nagorny, I., E-mail: lopin78@mail.ru

We study the effect of an external magnetic field on the properties of kink waves, propagating along a thin non-isothermal stratified and diverging magnetic flux tube. A wave equation, governing the propagation of kink waves under the adopted model is derived. It is shown that the vertical gradient of temperature introduces a spatially local cut-off frequency ω {sub c}. The vertical distribution of the cut-off frequency is calculated for the reference VAL-C model of the solar atmosphere and for different values of a ratio of external to internal magnetic fields. The results show that the cut-off frequency is negative belowmore » the temperature minimum due to the negative temperature gradient. In the chromosphere the cut-off frequency at a given height is smaller for a stronger external magnetic field. For the appropriate range of a ratio B{sub e} / B{sub i}  ≈ 0–0.8, the cutoff lies in the range ω{sub c}  ≈ 0.003–0.010 s{sup −1} (periods 600 < P{sub c} < 2000 s). The estimate of the cut-off frequency in the transition region is provided as well. In the propagating wave regime, the effective wave energy flux in the non-isothermal diverging flux tubes is the same as in the straight and homogeneous cylindrical waveguides. The obtained wave equation in the limit β  = 0 is used to study the kink oscillations of non-isothermal coronal loops. It is found that the gradient of temperature along the coronal loops reduces the frequency ratio of the first overtone to the fundamental mode, i.e., ω{sub 2}/ ω{sub 1} < 2. This reduction grows for a larger ratio of temperature at the loop top to the temperature at the footpoints. Moreover, the effect of reduction is most pronounced for the steeper temperature profiles.« less

Assessing the Wave Energy Potential of Jamaica, a Greater Antilles Island, through Dynamic Modelling

NASA Astrophysics Data System (ADS)

Daley, A. P., Jr.; Dorville, J. F. M.; Taylor, M. A.

2017-12-01

Globally wave energy has been on the rise as a result of the impacts of climate change and continuous fluctuation in oil prices. The water's inertia provides waves with greater stability than that of other renewable energy sources such as solar and wind. Jamaica is part of the Greater Antilles Arc and has over 1000 km of coast line with an abundance of shallow water approximately 80% within a 50km band. This configuration provides a wealth of sites for wave exploitation even in minimal wave energy conditions. Aside from harnessing the oceans waves converters can be viewed as a tool for protection of coastal areas against natural marine occurrences. Jamica has done extensive studies where solar, hydro and wind resouces are concerned. However, there has been no studies done to date on the country's wave energy resources.The aim of this study is to bridge this gap by characterizing Jamaica's wave energy resources generating in a half-closed Caribbean Sea using data available from: buoys, altimetric satellite, and numerical model. Available data has been used to assess the available resource on the coastal area for the last 12 years. Statistical analysis of the available energy is determined using the sea state (Hs, Tp and Dir) and the atmospheric forcing (10m-wind, atmospheric pressure, sea-air temperature) relating to the season.The chain of dynamical model is presented (WW3-SWAN-SWASH), allowing for the tracking of the propagation of the wave energy from an offshore region to nearshore zone along with their interaction with areas of shallow depth. This will provide a better assessment of the energy and the quality of the waves closer to the electrical grid.Climate prediction is used to estimate the sea state and wave energy exploitable up to 2100. An analysis of the possible usage of the available coastal resource up to 2100. The main results present small but exploitable resources with seasonal variability in the energy available but not wave direction.

Boring and Sealing Rock with Directed Energy Millimeter-Waves

NASA Astrophysics Data System (ADS)

Woskov, P.; Einstein, H. H.; Oglesby, K.

2015-12-01

Millimeter-wave directed energy is being investigated to penetrate into deep crystalline basement rock formations to lower well costs and to melt rocks, metals, and other additives to seal wells for applications that include nuclear waste storage and geothermal energy. Laboratory tests have established that intense millimeter-wave (MMW) beams > 1 kW/cm2 can melt and/ or vaporize hard crystalline rocks. In principle this will make it possible to create open boreholes and a method to seal them with a glass/ceramic liner and plug formed from the original rock or with other materials. A 10 kW, 28 GHz commercial (CPI) gyrotron system with a launched beam diameter of about 32 mm was used to heat basalt, granite, limestone, and sandstone specimens to temperatures over 2500 °C to create melts and holes. A calibrated 137 GHz radiometer view, collinear with the heating beam, monitored real time peak rock temperature. A water load surrounding the rock test specimen primarily monitored unabsorbed power at 28 GHz. Power balance analysis of the laboratory observations shows that the temperature rise is limited by radiative heat loss, which would be expected to be trapped in a borehole. The analysis also indicates that the emissivity (absorption efficiency) in the radiated infrared range is lower than the emissivity at 28 GHz, giving the MMW frequency range an important advantage for rock melting. Strength tests on one granite type indicated that heating the rock initially weakens it, but with exposure to higher temperatures the resolidified black glassy product regains strength. Basalt was the easiest to melt and penetrate, if a melt leak path was provided, because of its low viscosity. Full beam holes up to about 50 mm diameter (diffraction increased beam size) were achieved through 30 mm thick basalt and granite specimens. Laboratory experiments to form a seal in an existing hole have also been carried out by melting rock and a simulated steel casing.

Analysis of nonlocal phonon thermal conductivity simulations showing the ballistic to diffusive crossover

NASA Astrophysics Data System (ADS)

Allen, Philip B.

2018-04-01

Simulations [e.g., X. W. Zhou et al., Phys. Rev. B 79, 115201 (2009), 10.1103/PhysRevB.79.115201] show nonlocal effects of the ballistic/diffusive crossover. The local temperature has nonlinear spatial variation not contained in the local Fourier law j ⃗(r ⃗) =-κ ∇ ⃗T (r ⃗) . The heat current j ⃗(r ⃗) depends not just on the local temperature gradient ∇ ⃗T (r ⃗) but also on temperatures at points r⃗' within phonon mean free paths, which can be micrometers long. This paper uses the Peierls-Boltzmann transport theory in nonlocal form to analyze the spatial variation Δ T (r ⃗) . The relaxation-time approximation (RTA) is used because the full solution is very challenging. Improved methods of extrapolation to obtain the bulk thermal conductivity κ are proposed. Callaway invented an approximate method of correcting RTA for the q ⃗ (phonon wave vector or crystal momentum) conservation of N (Normal as opposed to Umklapp) anharmonic collisions. This method is generalized to the nonlocal case where κ (k ⃗) depends on the wave vector of the current j ⃗(k ⃗) and temperature gradient i k ⃗Δ T (k ⃗) .

Acoustic computer tomographic pyrometry for two-dimensional measurement of gases taking into account the effect of refraction of sound wave paths

NASA Astrophysics Data System (ADS)

Lu, J.; Wakai, K.; Takahashi, S.; Shimizu, S.

2000-06-01

The algorithm which takes into account the effect of refraction of sound wave paths for acoustic computer tomography (CT) is developed. Incorporating the algorithm of refraction into ordinary CT algorithms which are based on Fourier transformation is very difficult. In this paper, the least-squares method, which is capable of considering the refraction effect, is employed to reconstruct the two-dimensional temperature distribution. The refraction effect is solved by writing a set of differential equations which is derived from Fermat's theorem and the calculus of variations. It is impossible to carry out refraction analysis and the reconstruction of temperature distribution simultaneously, so the problem is solved using the iteration method. The measurement field is assumed to take the shape of a circle and 16 speakers, also serving as the receivers, are set around it isometrically. The algorithm is checked through computer simulation with various kinds of temperature distributions. It is shown that the present method which takes into account the algorithm of the refraction effect can reconstruct temperature distributions with much greater accuracy than can methods which do not include the refraction effect.

Skylab near-infrared observations of clouds indicating supercooled liquid water droplets

NASA Technical Reports Server (NTRS)

Curran, R. J.; Wu, M.-L. C.

1982-01-01

Orographically-induced lee-wave clouds were observed over New Mexico by a multichannel scanning radiometer on Skylab during December 1973. Channels centered at 0.83, 1.61 and 2.125 microns were used to determine the cloud optical thickness, thermodynamic phase and effective particle size. An additional channel centered at 11.4 microns was used to determine cloud-top temperature, which was corroborated through comparison with the stereographically determined cloud top altitudes and conventional temperature soundings. Analysis of the measured near-infrared reflection functions at 1.61 and 2.125 microns are most easily interpreted as indicating the presence of liquid-phase water droplets. This interpretation is not conclusive even after considerable effort to understand possible sources for misinterpretation. However, if accepted the resulting phase determination is considered anomalous due to the inferred cloud-top temperatures being in the -32 to -47 C range. Theory for the homogeneous nucleation of pure supercooled liquid water droplets predicts very short lifetimes for the liquid phase at these cold temperatures. A possible explanation for the observations is that the wave-clouds are composed of solution droplets. Impurities in the cloud droplets could decrease the homogeneous freezing rate for these droplets, permitting them to exist for a longer time in the liquid phase, at the cold temperatures found.

Observation of temperatures and emission rates from the OH and O 2 nightglow over a southern high latitude station

NASA Astrophysics Data System (ADS)

Chung, J.-K.; Kim, Y. H.; Won, Y.-I.; Moon, B. K.; Oh, T. H.

2006-01-01

A Spectral Airglow Temperature Imager (SATI) was operated at King Sejong Station (62°13'S, 58°47'W), Korea Antarctic Research Station during the period of March, 2002-September, 2003. We analyze rotational temperatures and emission rates of the O 2 (0-1) and OH (6-2) nightglows obtained at 67 nights with clear sky lasting more than 4 h. A spectral analysis of the dataset shows two dominant oscillations with periods of 4 and 6 h. The 6-h oscillations have a nearly constant phase, whereas the 4-h oscillations have nearly random phases. Although the harmonic periods of both oscillations are suggestive of tidal origin, the 4-h oscillation may have interference by other sources such as gravity waves. The 6-h oscillations could be interpreted as zonally symmetric non-migrating tides because migrating tides except high order modes have very weak amplitudes at high latitudes according to the classical tidal theory. For most cases of the observed oscillations the temperature peak leads the intensity peak, which is consistent with theoretical models for zonally symmetric tides, but contrary to other theoretical models for waves. It is needed to resolve among theoretical models whether or not zonally symmetric tide cause temperature variation prior to intensity variation in mesospheric airglows.

Color temperature’s impact on task performance and brainwaves of school-age children

PubMed Central

Park, YunHee

2015-01-01

[Purpose] This study investigated color temperature’s impact on task performance. It presents a scientific analysis of brainwave and task performance time changes, and the results of a self-report type survey. [Subjects] Twenty-four elementary school fifth-grade boys and girls with no visual problems participated in the experiment. [Methods] Physiological reaction times of task performance were measured in a laboratory that could fix and maintain color temperature. Brainwave changes and the task performance times were measured, and a self-report questionnaire was conducted in order to measure of emotional reactions. [Results] Regarding the brainwave changes associated with color temperature, alpha waves were emitted in the O2 area when puzzle tasks were illuminated by orange light and low and high beta waves were emitted in the F3 area under white light. Five items (Brilliant, Soft, Lively, Relaxed, Open) were reported predominantly in responses to orange light in the self-report questionnaire. [Conclusion] The results of this study show that relaxation and stability are not assured when the color temperature is low, and that concentration and cognitive activity are not necessarily easier when the color temperature is high. The color temperature change when performing tasks promoted emotional factors more than brainwave, a biological change. PMID:26644662

The impact of heat waves on surface urban heat island and local economy in Cluj-Napoca city, Romania

NASA Astrophysics Data System (ADS)

Herbel, Ioana; Croitoru, Adina-Eliza; Rus, Adina Viorica; Roşca, Cristina Florina; Harpa, Gabriela Victoria; Ciupertea, Antoniu-Flavius; Rus, Ionuţ

2017-07-01

The association between heat waves and the urban heat island effect can increase the impact on environment and society inducing biophysical hazards. Heat stress and their associated public health problems are among the most frequent. This paper explores the heat waves impact on surface urban heat island and on the local economy loss during three heat periods in Cluj-Napoca city in the summer of 2015. The heat wave events were identified based on daily maximum temperature, and they were divided into three classes considering the intensity threshold: moderate heat waves (daily maximum temperature exceeding the 90th percentile), severe heat waves (daily maximum temperature over the 95th percentile), and extremely severe heat waves (daily maximum temperature exceeding the 98th percentile). The minimum length of an event was of minimum three consecutive days. The surface urban heat island was detected based on land surface temperature derived from Landsat 8 thermal infrared data, while the economic impact was estimated based on data on work force structure and work productivity in Cluj-Napoca derived from the data released by Eurostat, National Bank of Romania, and National Institute of Statistics. The results indicate that the intensity and spatial extension of surface urban heat island could be governed by the magnitude of the heat wave event, but due to the low number of satellite images available, we should consider this information only as preliminary results. Thermal infrared remote sensing has proven to be a very efficient method to study surface urban heat island, due to the fact that the synoptic conditions associated with heat wave events usually favor cloud free image. The resolution of the OLI_TIRS sensor provided good results for a mid-extension city, but the low revisiting time is still a drawback. The potential economic loss was calculated for the working days during heat waves and the estimated loss reached more than 2.5 mil. EUR for each heat wave day at city scale, cumulating more than 38 mil. EUR for the three cases considered.

Understanding the ignition mechanism of high-pressure spray flames

DOE PAGES

Dahms, Rainer N.; Paczko, Günter A.; Skeen, Scott A.; ...

2016-10-25

A conceptual model for turbulent ignition in high-pressure spray flames is presented. The model is motivated by first-principles simulations and optical diagnostics applied to the Sandia n-dodecane experiment. The Lagrangian flamelet equations are combined with full LLNL kinetics (2755 species; 11,173 reactions) to resolve all time and length scales and chemical pathways of the ignition process at engine-relevant pressures and turbulence intensities unattainable using classic DNS. The first-principles value of the flamelet equations is established by a novel chemical explosive mode-diffusion time scale analysis of the fully-coupled chemical and turbulent time scales. Contrary to conventional wisdom, this analysis reveals thatmore » the high Damköhler number limit, a key requirement for the validity of the flamelet derivation from the reactive Navier–Stokes equations, applies during the entire ignition process. Corroborating Rayleigh-scattering and formaldehyde PLIF with simultaneous schlieren imaging of mixing and combustion are presented. Our combined analysis establishes a characteristic temporal evolution of the ignition process. First, a localized first-stage ignition event consistently occurs in highest temperature mixture regions. This initiates, owed to the intense scalar dissipation, a turbulent cool flame wave propagating from this ignition spot through the entire flow field. This wave significantly decreases the ignition delay of lower temperature mixture regions in comparison to their homogeneous reference. This explains the experimentally observed formaldehyde formation across the entire spray head prior to high-temperature ignition which consistently occurs first in a broad range of rich mixture regions. There, the combination of first-stage ignition delay, shortened by the cool flame wave, and the subsequent delay until second-stage ignition becomes minimal. A turbulent flame subsequently propagates rapidly through the entire mixture over time scales consistent with experimental observations. As a result, we demonstrate that the neglect of turbulence-chemistry-interactions fundamentally fails to capture the key features of this ignition process.« less

Analysis of Numerical Simulation Database for Pressure Fluctuations Induced by High-Speed Turbulent Boundary Layers

NASA Technical Reports Server (NTRS)

Duan, Lian; Choudhari, Meelan M.

2014-01-01

Direct numerical simulations (DNS) of Mach 6 turbulent boundary layer with nominal freestream Mach number of 6 and Reynolds number of Re(sub T) approximately 460 are conducted at two wall temperatures (Tw/Tr = 0.25, 0.76) to investigate the generated pressure fluctuations and their dependence on wall temperature. Simulations indicate that the influence of wall temperature on pressure fluctuations is largely limited to the near-wall region, with the characteristics of wall-pressure fluctuations showing a strong temperature dependence. Wall temperature has little influence on the propagation speed of the freestream pressure signal. The freestream radiation intensity compares well between wall-temperature cases when normalized by the local wall shear; the propagation speed of the freestream pressure signal and the orientation of the radiation wave front show little dependence on the wall temperature.

Pulse echo and combined resonance techniques: a full set of LGT acoustic wave constants and temperature coefficients.

PubMed

Sturtevant, Blake T; Davulis, Peter M; da Cunha, Mauricio Pereira

2009-04-01

This work reports on the determination of langatate elastic and piezoelectric constants and their associated temperature coefficients employing 2 independent methods, the pulse echo overlap (PEO) and a combined resonance technique (CRT) to measure bulk acoustic wave (BAW) phase velocities. Details on the measurement techniques are provided and discussed, including the analysis of the couplant material in the PEO technique used to couple signal to the sample, which showed to be an order of magnitude more relevant than the experimental errors involved in the data extraction. At room temperature, elastic and piezoelectric constants were extracted by the PEO and the CRT methods and showed results consistent to within a few percent for the elastic constants. Both raw acquired data and optimized constants, based on minimization routines applied to all the modes involved in the measurements, are provided and discussed. Comparison between the elastic constants and their temperature behavior with the literature reveals the recent efforts toward the consistent growth and characterization of LGT, in spite of significant variations (between 1 and 30%) among the constants extracted by different groups at room temperature. The density, dielectric permittivity constants, and respective temperature coefficients used in this work have also been independently determined based on samples from the same crystal boule. The temperature behavior of the BAW modes was extracted using the CRT technique, which has the advantage of not relying on temperature dependent acoustic couplants. Finally, the extracted temperature coefficients for the elastic and piezoelectric constants between room temperature and 120 degrees C are reported and discussed in this work.

Impacts of hot and cold temperature extremes on hospital admissions for cardiovascular diseases

NASA Astrophysics Data System (ADS)

Davídkovová, H.; Kyselý, J.; Kříž, B.

2010-09-01

Elevated mortality associated with high ambient temperatures in summer represents one of the main impacts of weather extremes on human society. Increases in mortality during heat waves were examined in many European countries; much less is known about the effects of heat waves on morbidity, measured for example by the number of hospital admissions. Relatively less understood is also cold-related mortality and morbidity in winter, when the relationships between weather and human health are more complex, less direct, and confounded by other factors such as epidemics of influenza/acute respiratory infections. The present study examines links between hot and cold temperature extremes and daily hospital admissions for cardiovascular diseases in the population of the Czech Republic over 1994-2007. We make use of a recently completed database of all admissions for cardiovascular diseases to hospitals in the area of the Czech Republic since 1994, with a detailed classification of diseases and detailed information concerning each patient (in total 1,467,675 hospital admissions over 1994-2007). The main goals of the study are (i) to identify excess/deficit morbidity during and after periods of heat waves in summer and cold spells in winter, (ii) to compare the links for individual diseases (e.g. acute myocardial infarction, I21; angina pectoris, I20; cerebral infarction, I63; brain ischemia, I64) and to identify those diagnoses that are most closely linked to weather, (iii) to identify population groups most vulnerable to temperature extremes, and (iv) to compare the links to temperature extremes for morbidity and mortality. Periods when morbidity data were affected by epidemics of influenza and acute respiratory infections in winter were excluded from the analysis.

Warm vegetarians? Heat waves and diet shifts in tadpoles.

PubMed

Carreira, B M; Segurado, P; Orizaola, G; Gonçalves, N; Pinto, V; Laurila, A; Rebelo, R

2016-11-01

Temperature can play an important role in determining the feeding preferences of ectotherms. In light of the warmer temperatures arising with the current climatic changes, omnivorous ectotherms may perform diet shifts toward higher herbivory to optimize energetic intake. Such diet shifts may also occur during heat waves, which are projected to become more frequent, intense, and longer lasting in the future. Here, we investigated how heat waves of different duration affect feeding preferences in omnivorous anuran tadpoles and how these choices affect larval life history. In laboratory experiments, we fed tadpoles of three species on animal, plant, or mixed diet and exposed them to short heat waves (similar to the heat waves these species experience currently) or long heat waves (predicted to increase under climate change). We estimated the dietary choices of tadpoles fed on the mixed diet using stable isotopes and recorded tadpole survival and growth, larval period, and mass at metamorphosis. Tadpole feeding preferences were associated with their thermal background, with herbivory increasing with breeding temperature in nature. Patterns in survival, growth, and development generally support decreased efficiency of carnivorous diets and increased efficiency or higher relative quality of herbivorous diets at higher temperatures. All three species increased herbivory in at least one of the heat wave treatments, but the responses varied among species. Diet shifts toward higher herbivory were maladaptive in one species, but beneficial in the other two. Higher herbivory in omnivorous ectotherms under warmer temperatures may impact species differently and further contribute to changes in the structure and function of freshwater environments. © 2016 by the Ecological Society of America.

Estimating and projecting the effect of cold waves on mortality in 209 US cities.

PubMed

Wang, Yan; Shi, Liuhua; Zanobetti, Antonella; Schwartz, Joel D

2016-09-01

The frequency, duration, and intensity of cold waves are expected to decrease in the near future under the changing climate. However, there is a lack of understanding on future mortality related to cold waves. The present study conducted a large-scale national projection to estimate future mortality attributable to cold waves during 1960-2050 in 209 US cities. Cold waves were defined as two, three, or at least four consecutive days with daily temperature lower than the 5th percentile of temperatures in each city. The lingering period of a cold wave was defined as the non-cold wave days within seven days following that cold wave period. First, with 168million residents in 209 US cities during 1962-2006, we fitted over-dispersed Poisson regressions to estimate the immediate and lingering effects of cold waves on mortality and tested if the associations were modified by the duration of cold waves, the intensity of cold waves, and mean winter temperature (MWT). Then we projected future mortality related to cold waves using 20 downscaled climate models. Here we show that the cold waves (both immediate and lingering) were associated with an increased but small risk of mortality. The associations varied substantially across climate regions. The risk increased with the duration and intensity of cold waves but decreased with MWT. The projected mortality related to cold waves would decrease from 1960 to 2050. Such a decrease, however, is small and may not be able to offset the potential increase in heat-related deaths if the adaptation to heat is not adequate. Copyright © 2016 Elsevier Ltd. All rights reserved.

Ferromagnetic resonance in bulk nanocrystalline Ni

NASA Astrophysics Data System (ADS)

Prakash Madduri, P. V.; Mathew, S. P.; Kaul, S. N.

2018-03-01

A detailed lineshape analysis of the ferromagnetic resonance (FMR) spectra taken on pulse electrodeposited nanocrystalline (nc-) Ni sheets (with the average crystallite size, d, varying from 10 nm to 40 nm) at temperatures ranging from 113 K to 325 K yield accurate values for saturation magnetization, Ms (T), Landé splitting factor, g, anisotropy field, Hk (T) , resonance field, Hres , and FMR linewidth, ΔHpp (T) . Thermally-excited spin-wave (SW) excitations completely account for Ms (T) and the SW description of Ms (T) gives the values for the saturation magnetization and spin-wave stiffness at absolute zero of temperature, i.e., Ms (0) and D0 , for nc-Ni samples of different d that are in excellent agreement with the corresponding values deduced previously from an elaborate SW analysis of the bulk magnetization data. While Ms (0) varies with d as Ms (0) d - 3 / 2,D0 follows the power law D0 ∼d 4 / 3 . The angular variations of Hres in the 'in-plane' as well as 'out-of-plane' sample configurations, demonstrate that the main contribution to Hk (T) comes from the cubic magnetocrystalline anisotropy. The exchange-conductivity mechanism describes the observed thermal decline of ΔHpp reasonably well but fails to explain the very large magnitude of ΔHpp at any given temperature. By comparison, the Landau-Lifshitz-Gilbert (LLG) damping gives a much greater contribution to ΔHpp but the LLG contribution is relatively insensitive to temperature.

Kinetic water-bag model of global collisional drift waves and ion temperature gradient instabilities in cylindrical geometry

NASA Astrophysics Data System (ADS)

Gravier, E.; Plaut, E.

2013-04-01

Collisional drift waves and ion temperature gradient (ITG) instabilities are studied using a linear water-bag kinetic model [P. Morel et al., Phys. Plasmas 14, 112109 (2007)]. An efficient spectral method, already validated in the case of drift waves instabilities [E. Gravier et al., Eur. Phys. J. D 67, 7 (2013)], allows a fast solving of the global linear problem in cylindrical geometry. The comparison between the linear ITG instability properties thus computed and the ones given by the COLUMBIA experiment [R. G. Greaves et al., Plasma Phys. Controlled Fusion 34, 1253 (1992)] shows a qualitative agreement. Moreover, the transition between collisional drift waves and ITG instabilities is studied theoretically as a function of the ion temperature profile.

Dust Acoustic Solitary Waves in Dusty Plasma with Trapped Electrons Having Different Temperature Nonthermal Ions

NASA Astrophysics Data System (ADS)

Deka, Manoj Kr.

2016-12-01

In this report, a detailed investigation on the study of dust acoustics solitary waves solution with negatively dust charge fluctuation in dusty plasma corresponding to lower and higher temperature nonthermal ions with trapped electrons is presented. We consider temporal variation of dust charge as a source of dissipation term to derive the lower order modified Kadomtsev-Petviashvili equation by using the reductive perturbation technique. Solitary wave solution is obtained with the help of sech method in presence of trapped electrons and low (and high) temperature nonthermal ions. Both nonthermality of ions and trapped state of the electrons are found to have an imperative control on the nonlinear coefficient, dissipative coefficient as well as height of the wave potential.

First results of warm mesospheric temperature over Gadanki (13.5°N, 79.2°E) during the sudden stratospheric warming of 2009

NASA Astrophysics Data System (ADS)

Sridharan, S.; Raghunath, K.; Sathishkumar, S.; Nath, D.

2010-09-01

Rayleigh lidar observations at Gadanki (13.5°N, 79.2°E) show an enhancement of the nightly mean temperature by 10-15 K at altitudes 70-80 km and of gravity wave potential energy at 60-70 km during the 2009 major stratospheric warming event. An enhanced quasi-16-day wave activity is observed at 50-70 km in the wavelet spectrum of TIMED-SABER temperatures, possibly due to the absence of a critical level in the low-latitude stratosphere because of less westward winds caused by this warming event. The observed low-latitude mesospheric warming could be due to wave breaking, as waves are damped at 80 km.

Simultaneous Rayleigh lidar and airglow measurements of middle atmospheric waves over low latitudes in India

NASA Astrophysics Data System (ADS)

Taori, A.; Kamalakar, V.; Raghunath, K.; Rao, S. V. B.; Russell, J. M.

2012-04-01

We utilize simultaneous Rayleigh lidar and mesospheric OH and O2 airglow measurements to identify the dominant and propagating waves within 40-95 km altitude regions over a low latitude station Gadanki (13.8° N, 79.2 °E). It is found that waves with 0.4-0.6 h periodicity are common throughout the altitude range of 40-95 km with significant amplitudes. The ground based temperature measurements with lidar and airglow monitoring are found to compare well with SABER data. With simultaneous Rayleigh lidar (temperature) and mesospheric airglow (emission intensity and temperature) measurements, we estimate the amplitude growth and Krassovsky parameters to characterize the propagation and dissipation of these upward propagating waves.

The α-γ-ɛ triple point and phase boundaries of iron under shock compression

NASA Astrophysics Data System (ADS)

Li, Jun; Wu, Qiang; Xue, Tao; Geng, Huayun; Yu, Jidong; Jin, Ke; Li, Jiabo; Tan, Ye; Xi, Feng

2017-07-01

The phase transition of iron under shock compression has attracted much attention in recent decades because of its importance in fields such as condensed matter physics, geophysics, and metallurgy. At room temperature, the transition of iron from the α-phase (bcc) to the ɛ-phase (hpc) occurs at a stress of 13 GPa. At high temperature, a triple point followed by transformation to the γ-phase (fcc) is expected. However, the details of the high-temperature phase transitions of iron are still under debate. Here, we investigate the phase-transition behavior of polycrystalline iron under compression from room temperature to 820 K. The results show that the shock-induced phase transition is determined unequivocally from the measured three-wave-structure profiles, which clearly consist of an elastic wave, a plastic wave, and a phase-transition wave. The phase transition is temperature-dependent, with an average rate Δσtr/ΔT of -6.91 MPa/K below 700 K and -34.7 MPa/K at higher temperatures. The shock α-ɛ and α-γ phase boundaries intersect at 10.6 ± 0.53 GPa and 763 K, which agrees with the α-ɛ-γ triple point from early shock wave experiments and recent laser-heated diamond-anvil cell resistivity and in situ X-ray diffraction data but disagrees with the shock pressure-temperature phase diagram reported in 2009 by Zaretsky [J. Appl. Phys. 106, 023510 (2009)].

Variations in Temperature at the Base of the Lithosphere Beneath the Archean Superior Province, Canada

NASA Astrophysics Data System (ADS)

Mareschal, J.; Jaupart, C. P.

2013-12-01

Most of the variations in surface heat flux in stable continents are caused by variations in crustal heat production, with an almost uniform heat flux at the base of the crust ( 15+/-3 mW/m2). Such relatively small differences in Moho heat flux cannot be resolved by heat flow data alone, but they lead to important lateral variations in lithospheric temperatures and thicknesses. In order to better constrain temperatures in the lower lithosphere, we have combined surface heat flow and heat production data from the southern Superior Province in Canada with vertical shear wave velocity profiles obtained from surface wave inversion. We use the Monte-Carlo method to generate lithospheric temperature profiles from which shear wave velocity can be calculated for a given mantle composition. We eliminate thermal models which yield lithospheric and sub-lithospheric velocities that do not fit the shear wave velocity profile. Surface heat flux being constrained, the free parameters of the thermal model are: the mantle heat flux, the mantle heat production, the crustal differentiation index (ratio of surface to bulk crustal heat production) and the temperature of the mantle isentrope. Two conclusions emerge from this study. One is that, for some profiles, the vertical variations in shear wave velocities cannot be accounted for by temperature alone but also require compositional changes within the lithosphere. The second is that there are long wavelength horizontal variations in mantle temperatures (~80-100K) at the base of the lithosphere and in the mantle below

Simulated GOLD Observations of Atmospheric Waves

NASA Astrophysics Data System (ADS)

Correira, J.; Evans, J. S.; Lumpe, J. D.; Rusch, D. W.; Chandran, A.; Eastes, R.; Codrescu, M.

2016-12-01

The Global-scale Observations of the Limb and Disk (GOLD) mission will measure structures in the Earth's airglow layer due to dynamical forcing by vertically and horizontally propagating waves. These measurements focus on global-scale structures, including compositional and temperature responses resulting from dynamical forcing. Daytime observations of far-UV emissions by GOLD will be used to generate two-dimensional maps of the ratio of atomic oxygen and molecular nitrogen column densities (ΣO/N2 ) as well as neutral temperature that provide signatures of large-scale spatial structure. In this presentation, we use simulations to demonstrate GOLD's capability to deduce periodicities and spatial dimensions of large-scale waves from the spatial and temporal evolution observed in composition and temperature maps. Our simulations include sophisticated forward modeling of the upper atmospheric airglow that properly accounts for anisotropy in neutral and ion composition, temperature, and solar illumination. Neutral densities and temperatures used in the simulations are obtained from global circulation and climatology models that have been perturbed by propagating waves with a range of amplitudes, periods, and sources of excitation. Modeling of airglow emission and predictions of ΣO/N2 and neutral temperatures are performed with the Atmospheric Ultraviolet Radiance Integrated Code (AURIC) and associated derived product algorithms. Predicted structure in ΣO/N2 and neutral temperature due to dynamical forcing by propagating waves is compared to existing observations. Realistic GOLD Level 2 data products are generated from simulated airglow emission using algorithm code that will be implemented operationally at the GOLD Science Data Center.

Capability of simultaneous Rayleigh LiDAR and O2 airglow measurements in exploring the short period wave characteristics

NASA Astrophysics Data System (ADS)

Taori, Alok; Raghunath, Karnam; Jayaraman, Achuthan

We use combination of simultaneous measurements made with Rayleigh lidar and O2 airglow monitoring to improve lidar investigation capability to cover a higher altitude range. We feed instantaneous O2 airglow temperatures instead the model values at the top altitude for subsequent integration method of temperature retrieval using Rayleigh lidar back scattered signals. Using this method, errors in the lidar temperature estimates converges at higher altitudes indicating better altitude coverage compared to regular methods where model temperatures are used instead of real-time measurements. This improvement enables the measurements of short period waves at upper mesospheric altitudes (~90 km). With two case studies, we show that above 60 km the few short period wave amplitude drastically increases while, some of the short period wave show either damping or saturation. We claim that by using such combined measurements, a significant and cost effective progress can be made in the understanding of short period wave processes which are important for the coupling across the different atmospheric regions.

Development of Laser-induced Grating Spectroscopy for Underwater Temperature Measurement in Shock Wave Focusing Regions

NASA Technical Reports Server (NTRS)

Gojani, Ardian B.; Danehy, Paul M.; Alderfer, David W.; Saito, Tsutomu; Takayama, Kazuyoshi

2003-01-01

In Extracorporeal Shock Wave Lithotripsy (ESWL) underwater shock wave focusing generates high pressures at very short duration of time inside human body. However, it is not yet clear how high temperatures are enhanced at the spot where a shock wave is focused. The estimation of such dynamic temperature enhancements is critical for the evaluation of tissue damages upon shock loading. For this purpose in the Interdisciplinary Shock Wave Research Center a technique is developed which employs laser induced thermal acoustics or Laser Induced Grating Spectroscopy. Unlike most of gasdynamic methods of measuring physical quantities this provides a non-invasive one having spatial and temporal resolutions of the order of magnitude of 1.0 mm3 and 400 ns, respectively. Preliminary experiments in still water demonstrated that this method detected sound speed and hence temperature in water ranging 283 K to 333 K with errors of 0.5%. These results may be used to empirically establish the equation of states of water, gelatin or agar cells which will work as alternatives of human tissues.

Electronegative nonlinear oscillating modes in plasmas

NASA Astrophysics Data System (ADS)

Panguetna, Chérif Souleman; Tabi, Conrad Bertrand; Kofané, Timoléon Crépin

2018-02-01

The emergence of nonlinear modulated waves is addressed in an unmagnetized electronegative plasma made of Boltzmann electrons, Boltzmann negative ions and cold mobile positive ions. The reductive perturbation method is used to reduce the dynamics of the whole system to a cubic nonlinear Schrödinger equation, whose the nonlinear and dispersion coefficients, P and Q, are function of the negative ion parameters, namely the negative ion concentration ratio (α) and the electron-to-negative ion temperature ratio (σn). It is observed that these parameters importantly affect the formation of modulated ion-acoustic waves, either as exact solutions or via the activation of modulational instability. Especially, the theory of modulational instability is used to show the correlation between the parametric analysis and the formation of modulated solitons, obtained here as bright envelopes and kink-wave solitons.

Charge density wave modulation and gap measurements in CeTe 3

DOE PAGES

Ralevic, U.; Lazarevic, N.; Baum, A.; ...

2016-10-14

Here, we present a study of charge density wave (CDW) ordering in CeTe 3 at room temperature using a scanning tunneling microscope and Raman spectroscopy. Two characteristic CDW ordering wave vectors obtained from the Fourier analysis are assessed to be |c* – q|=4.19nm –1 and |q|=10.26nm –1 where |c*|=2π/c is the reciprocal lattice vector. The scanning tunneling spectroscopy measurements, along with inelastic light (Raman) scattering measurements, show a CDW gap Δ max of approximately 0.37 eV. In addition to the CDW modulation, we observe an organization of the Te sheet atoms in an array of alternating V- and N-shaped groupsmore » along the CDW modulation, as predicted in the literature.« less

Beneficial effects of footbaths in controlling spasticity after stroke

NASA Astrophysics Data System (ADS)

Matsumoto, Shuji; Shimodozono, Megumi; Etoh, Seiji; Shimozono, Yurika; Tanaka, Nobuyuki; Kawahira, Kazumi

2010-07-01

Footbaths are considered to provide beneficial thermal therapy for post-stroke patients with spasticity, but their anti-spastic effects have not been investigated comprehensively. The present study aimed to evaluate alterations in motor-neuron excitability using F-wave parameters in post-stroke patients with spastic hemiplegia. Subjects’ legs below the knee joint were immersed in water at 41°C and F-wave recordings were made over the abductor hallucis muscle before, immediately after, and 30 min after thermal treatment. Antidromic stimulation was performed on the tibial nerve at the ankle. Measurements included F-wave amplitude, F-wave/M-response ratio, changes in modified Ashworth scale (MAS), body temperature and surface-skin temperature. The mean values of both F-wave parameters were higher on the affected side before footbath treatment. In post-stroke patients, the mean values of F-wave parameters were significantly reduced after footbath treatment ( P < 0.01). The anti-spastic effects of footbath treatment were indicated by decreased F-wave parameters, in parallel with decreases in MAS. Body temperature was significantly increased both immediately after, and 30 min following footbath treatment in both groups, which appeared to play an important role in decreased spasticity. Surface-skin temperature increased immediately after footbath treatment in both groups and returned to baseline 30 min later. These findings demonstrate that the use of footbaths is an effective nonpharmacological anti-spastic treatment that might facilitate stroke rehabilitation.

Synoptic-scale characteristics and atmospheric controls of summer heat waves in China

NASA Astrophysics Data System (ADS)

Wang, Weiwen; Zhou, Wen; Li, Xiuzhen; Wang, Xin; Wang, Dongxiao

2016-05-01

Summer heat waves with persistent extreme high temperatures have been occurring with increasing frequency in recent decades. These extreme events have disastrous consequences for human health, economies, and ecosystems. In this study, we examine three summers with intense and protracted heat waves: the summers of 2003, 2006, and 2013, with high temperatures located mainly in southeastern, southwestern, and eastern China, respectively. The synoptic-scale characteristics of these heat waves and associated atmospheric circulation anomalies are investigated. In the early heat wave episode of 2003, a heat center was located in the southeast coastal provinces during the first 20 days of July. The maximum southward displacement of the East Asian jet stream (EAJS) induced anticyclonic anomalies to the south, associated with southwestward intensification of the western North Pacific subtropical high (WNPSH), and extreme high temperatures were found only to the south of the Yangtze River. In the later episode, a poleward displacement of the EAJS and an enhanced WNPSH over the midlatitudes of eastern China resulted in a "heat dome" over the region, and the heat wave extended northward to cover a larger area of eastern China. The coupling between the westward-enhanced WNPSH and poleward-displaced EAJS was found in the East China heat wave of 2013 as well. But the area of high temperatures reached far to the north in August 2013, with below-normal temperatures located in a small region of South China. In the 2006 southwestern drought and heat wave, extreme poleward displacement of the EAJS, associated with extraordinary westward extension of the WNSPH, resulted in further blocking of the moisture supply from the southwest monsoon. Large-scale moisture deficiencies, dry conditions, and downslope winds were common features of all investigated heat wave episodes. But in 2006, low-level heat lows associated with a well-mixed layer due to intensive daytime heating and atmospheric turbulence were emphasized.

Excitation of acoustic oscillations in superconducting films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Golub, A.A.

1973-11-01

A study is made of the excitation of sound in a superconducting film by electromagnetic waves incident on the surface of the film. It is assumed that the thickness of the film d is much greater than the penetration depth of the field. If the acoustic wave is damped over a distance of the order of d, traveling acoustic waves can be excited in the superconductor; otherwise, standing waves are excited. The low-temperature contribution of acoustic oseillations to the surface resistence of pure superconductors ia calculated. At very low temperatures, the absorption of electromagnetic waves is mainly governed by themore » loss due to acoustic oscillations. (auth)« less

Piezoelectric shear wave resonator and method of making same

DOEpatents

Wang, J.S.; Lakin, K.M.; Landin, A.R.

1985-05-20

An acoustic shear wave resonator comprising a piezoelectric film having its C-axis substantially inclined from the film normal such that the shear wave coupling coefficient significantly exceeds the longitudinal wave coupling coefficient, whereby the film is capable of shear wave resonance, and means for exciting said film to resonate. The film is prepared by deposition in a dc planar magnetron sputtering system to which a supplemental electric field is applied. The resonator structure may also include a semiconductor material having a positive temperature coefficient of resonance such that the resonator has a temperature coefficient of resonance approaching 0 ppM//sup 0/C.

Piezoelectric shear wave resonator and method of making same

DOEpatents

Wang, J.S.; Lakin, K.M.; Landin, A.R.

1983-10-25

An acoustic shear wave resonator comprising a piezoelectric film having its C-axis substantially inclined from the film normal such that the shear wave coupling coefficient significantly exceeds the longitudinal wave coupling coefficient, whereby the film is capable of shear wave resonance, and means for exciting said film to resonate. The film is prepared by deposition in a dc planar magnetron sputtering system to which a supplemental electric field is applied. The resonator structure may also include a semiconductor material having a positive temperature coefficient of resonance such that the resonator has a temperature coefficient of resonance approaching 0 ppM//sup 0/C.

Ultrasonic Seismic Wave Elastic Moduli and Attenuation, Petro physical Models and Work Flows for Better Subsurface Imaging Related to Monitoring of Sequestrated Supercritical CO2 and Geothermal Energy Exploration

NASA Astrophysics Data System (ADS)

Harbert, W.; Delaney, D.; Mur, A. J.; Purcell, C.; Zorn, E.; Soong, Y.; Crandall, D.; Haljasmaa, I.

2016-12-01

To better understand the petrophysical response at ultrasonic frequencies in rhyolite and carbonate (relevant to CO2 storage and CO2 enhanced oil recovery) lithologies we conducted core analysis incorporating variation in temperature, effective pressure and pore filling fluid. Ultrasonic compressive and shear wave (VP, VS1 and VS2) velocities were measured allowing calculation of the Bulk modulus (K), Young's modulus (E), Lamè's first parameter (λ), Shear modulus (G), Poisson's ratio (ν), and P-wave modulus (M). In addition, from the ultrasonic waveform data collected, we employed the spectral ratio method to estimate the quality factor. Carbonate samples were tested dry, using atmospheric gas as the pore phase, and with deionized water, oil, and supercritical CO2. We observed that Qp was directly proportional to effective pressure in our rhyolite samples. In addition, we observed effects of core anisotropy on Qp, however this was not apparent in higher porosity samples. Increasing effective pressure seems to decrease the effects of ultrasonic P-wave anisotropy. Qp was inversely proportional to temperature, however this was not observed for higher porosity samples. Qp was highly dependent on the rock porosity. Higher porosity samples displayed significantly lower values of Qp. In our experiments we observed that ultrasonic wave scattering due to heterogeneities in the carbonate samples was dominant. Although we observed lower μρ values, trends in our data strongly agreed with the model proposed workers interpreting AVO trends in a LMR cross plot space. We found that μρ was proportional to temperature while λρ was temperature independent and that λρ-μρ trends were extremely dependent on porosity. Higher porosity results in lower values for both λρ and μρ. The presence of fluids causes a distinct shift in λρ values, an observation which could provide insight into subsurface exploration using amplitude variation with offset (AVO) classification. We present approaches to incorporate these laboratory results into well log calibrated MATLAB based Gassmann-Biot fluid substitution models incorporating compliant porosity, Thomsen parameters models that utilize orthorhombic velocity anisotropy to predict seismic responses.

THE FORMATION AND EARLY EVOLUTION OF A CORONAL MASS EJECTION AND ITS ASSOCIATED SHOCK WAVE ON 2014 JANUARY 8

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wan Linfeng; Cheng, Xin; Shi, Tong

2016-08-01

In this paper, we study the formation and early evolution of a limb coronal mass ejection (CME) and its associated shock wave that occurred on 2014 January 8. The extreme ultraviolet (EUV) images provided by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory disclose that the CME first appears as a bubble-like structure. Subsequently, its expansion forms the CME and causes a quasi-circular EUV wave. Interestingly, both the CME and the wave front are clearly visible at all of the AIA EUV passbands. Through a detailed kinematical analysis, it is found that the expansion of the CMEmore » undergoes two phases: a first phase with a strong but transient lateral over-expansion followed by a second phase with a self-similar expansion. The temporal evolution of the expansion velocity coincides very well with the variation of the 25–50 keV hard X-ray flux of the associated flare, which indicates that magnetic reconnection most likely plays an important role in driving the expansion. Moreover, we find that, when the velocity of the CME reaches ∼600 km s{sup −1}, the EUV wave starts to evolve into a shock wave, which is evidenced by the appearance of a type II radio burst. The shock’s formation height is estimated to be ∼0.2 R {sub sun}, which is much lower than the height derived previously. Finally, we also study the thermal properties of the CME and the EUV wave. We find that the plasma in the CME leading front and the wave front has a temperature of ∼2 MK, while that in the CME core region and the flare region has a much higher temperature of ≥8 MK.« less

LOFAR observations of the quiet solar corona

NASA Astrophysics Data System (ADS)

Vocks, C.; Mann, G.; Breitling, F.; Bisi, M. M.; Dąbrowski, B.; Fallows, R.; Gallagher, P. T.; Krankowski, A.; Magdalenić, J.; Marqué, C.; Morosan, D.; Rucker, H.

2018-06-01

Context. The quiet solar corona emits meter-wave thermal bremsstrahlung. Coronal radio emission can only propagate above that radius, Rω, where the local plasma frequency equals the observing frequency. The radio interferometer LOw Frequency ARray (LOFAR) observes in its low band (10-90 MHz) solar radio emission originating from the middle and upper corona. Aims: We present the first solar aperture synthesis imaging observations in the low band of LOFAR in 12 frequencies each separated by 5 MHz. From each of these radio maps we infer Rω, and a scale height temperature, T. These results can be combined into coronal density and temperature profiles. Methods: We derived radial intensity profiles from the radio images. We focus on polar directions with simpler, radial magnetic field structure. Intensity profiles were modeled by ray-tracing simulations, following wave paths through the refractive solar corona, and including free-free emission and absorption. We fitted model profiles to observations with Rω and T as fitting parameters. Results: In the low corona, Rω < 1.5 solar radii, we find high scale height temperatures up to 2.2 × 106 K, much more than the brightness temperatures usually found there. But if all Rω values are combined into a density profile, this profile can be fitted by a hydrostatic model with the same temperature, thereby confirming this with two independent methods. The density profile deviates from the hydrostatic model above 1.5 solar radii, indicating the transition into the solar wind. Conclusions: These results demonstrate what information can be gleaned from solar low-frequency radio images. The scale height temperatures we find are not only higher than brightness temperatures, but also than temperatures derived from coronograph or extreme ultraviolet (EUV) data. Future observations will provide continuous frequency coverage. This continuous coverage eliminates the need for local hydrostatic density models in the data analysis and enables the analysis of more complex coronal structures such as those with closed magnetic fields.

Studies on thermo-elastic heating of horns used in ultrasonic plastic welding.

PubMed

Roopa Rani, M; Prakasan, K; Rudramoorthy, R

2015-01-01

Ultrasonic welding horn is half wavelength section or tool used to focus the ultrasonic vibrations to the components being welded. The horn is designed in such a way that it maximizes the amplitude of the sound wave passing through it. The ends of the horn represent the displacement anti-nodes and the center the 'node' of the wave. As the horns perform 20,000 cycles of expansion and contraction per second, they are highly stressed at the nodes and are heated owing to thermo-elastic effects. Considerable temperature rise may be observed in the horn, at the nodal region when working at high amplitudes indicating high stress levels leading to failure of horns due to cyclic loading. The limits for amplitude must therefore be evaluated for the safe working of the horn. Horns made of different materials have different thermo-elastic behaviors and hence different temperatures at the nodes and antinodes. This temperature field can be used as a control mechanism for setting the amplitude/weld parameters. Safe stress levels can be predicted using modal and harmonic analyses followed by a stress analysis to study the effect of cyclic loads. These are achieved using 'Ansys'. The maximum amplitude level obtained from the stress analysis is used as input for 'Comsol' to predict the temperature field. The actual temperature developed in the horn during operation is measured using infrared camera and compared with the simulated temperature. From experiments, it is observed that horn made of titanium had the lowest temperature rise at the critical region and can be expected to operate at amplitudes up to 77 μm without suffering failure due to cyclic loading. The method of predicting thermo-elastic stresses and temperature may be adopted by the industry for operating the horn within the safe stress limits thereby extending the life of the horn. Copyright © 2014 Elsevier B.V. All rights reserved.

Statistical characterization of high-to-medium frequency mesoscale gravity waves by lidar-measured vertical winds and temperatures in the MLT

NASA Astrophysics Data System (ADS)

Lu, Xian; Chu, Xinzhao; Li, Haoyu; Chen, Cao; Smith, John A.; Vadas, Sharon L.

2017-09-01

We present the first statistical study of gravity waves with periods of 0.3-2.5 h that are persistent and dominant in the vertical winds measured with the University of Colorado STAR Na Doppler lidar in Boulder, CO (40.1°N, 105.2°W). The probability density functions of the wave amplitudes in temperature and vertical wind, ratios of these two amplitudes, phase differences between them, and vertical wavelengths are derived directly from the observations. The intrinsic period and horizontal wavelength of each wave are inferred from its vertical wavelength, amplitude ratio, and a designated eddy viscosity by applying the gravity wave polarization and dispersion relations. The amplitude ratios are positively correlated with the ground-based periods with a coefficient of 0.76. The phase differences between the vertical winds and temperatures (φW -φT) follow a Gaussian distribution with 84.2±26.7°, which has a much larger standard deviation than that predicted for non-dissipative waves ( 3.3°). The deviations of the observed phase differences from their predicted values for non-dissipative waves may indicate wave dissipation. The shorter-vertical-wavelength waves tend to have larger phase difference deviations, implying that the dissipative effects are more significant for shorter waves. The majority of these waves have the vertical wavelengths ranging from 5 to 40 km with a mean and standard deviation of 18.6 and 7.2 km, respectively. For waves with similar periods, multiple peaks in the vertical wavelengths are identified frequently and the ones peaking in the vertical wind are statistically longer than those peaking in the temperature. The horizontal wavelengths range mostly from 50 to 500 km with a mean and median of 180 and 125 km, respectively. Therefore, these waves are mesoscale waves with high-to-medium frequencies. Since they have recently become resolvable in high-resolution general circulation models (GCMs), this statistical study provides an important and timely reference for them.

Heat waves imposed during early pod development in soybean (Glycine max) cause significant yield loss despite a rapid recovery from oxidative stress.

PubMed

Siebers, Matthew H; Yendrek, Craig R; Drag, David; Locke, Anna M; Rios Acosta, Lorena; Leakey, Andrew D B; Ainsworth, Elizabeth A; Bernacchi, Carl J; Ort, Donald R

2015-08-01

Heat waves already have a large impact on crops and are predicted to become more intense and more frequent in the future. In this study, heat waves were imposed on soybean using infrared heating technology in a fully open-air field experiment. Five separate heat waves were applied to field-grown soybean (Glycine max) in central Illinois, three in 2010 and two in 2011. Thirty years of historical weather data from Illinois were analyzed to determine the length and intensity of a regionally realistic heat wave resulting in experimental heat wave treatments during which day and night canopy temperatures were elevated 6 °C above ambient for 3 days. Heat waves were applied during early or late reproductive stages to determine whether and when heat waves had an impact on carbon metabolism and seed yield. By the third day of each heat wave, net photosynthesis (A), specific leaf weight (SLW), and leaf total nonstructural carbohydrate concentration (TNC) were decreased, while leaf oxidative stress was increased. However, A, SLW, TNC, and measures of oxidative stress were no different than the control ca. 12 h after the heat waves ended, indicating rapid physiological recovery from the high-temperature stress. That end of season seed yield was reduced (~10%) only when heat waves were applied during early pod developmental stages indicates the yield loss had more to do with direct impacts of the heat waves on reproductive process than on photosynthesis. Soybean was unable to mitigate yield loss after heat waves given during late reproductive stages. This study shows that short high-temperature stress events that reduce photosynthesis and increase oxidative stress resulted in significant losses to soybean production in the Midwest, U.S. The study also suggests that to mitigate heat wave-induced yield loss, soybean needs improved reproductive and photosynthetic tolerance to high but increasingly common temperatures. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

The variability of temperature and precipitation over Korean Peninsula induced by off-equatorial western Pacific precipitation during boreal summer

NASA Astrophysics Data System (ADS)

Jeong, Yerim; Ham, Yoo-Geun

2016-04-01

The convection activity and variability are active in Tropic-subtropic area because of equatorial warm pool. The variability's impacts on not only subtropic also mid-latitude. The impact effects on through teleconnection between equatorial and mid-latitude like Pacific-Japan(PJ) pattern. In this paper, two groups are divided based on PJ pattern and JJA Korean precipitation for the analysis that Korean precipitation is affected by PJ pattern. 'PJ+NegKorpr' is indicated when PJ pattern occur that JJA(Jun-July_August) Korean precipitation has negative value. In this case, positive precipitation in subtropic is expanded to central Pacific. And the positive precipitation's pattern is increasing toward north. Because, the subtropical south-eastly wind is forming subtropical precipitation's pattern through cold Kelvin wave is expanding eastward. Cold Kelvin wave is because of Indian negative SST. Also, Korea has negative moisture advection and north-eastly is the role that is moving high-latitude's cold and dry air to Korea. So strong high pressure is formed in Korea. The strong high pressure involves that short wave energy is increasing on surface. As a result, The surface temperature is increased on Korea. But the other case, that 'PJ_Only' case, is indicated when PJ pattern occur and JJA Korean precipitation doesn't have negative value over significant level. The subtropic precipitation's pattern in 'PJ_Only' shows precipitation is confined in western Pacific and expended northward to 25°N near 130°E. And tail of precipitation is toward equatorial(south-eastward). Also, Korean a little positive moisture advection and south-westly is the role that is moving low-latitude's warm and wet air to Korea. So weak high pressure is formed in Korea. The weak high pressure influence amount of short wave energy, so Korean surface temperature is lower. In addition, the case of 'PJ_Only' and Pacific Decal Oscillation(PDO) are occur at the same time has negative impact in Korea temperature through subtropical cyclone and positive PDO. The positive PDO is the role that negative temperature in Korea. So, Korean temperature confined lower by subtropical cyclone and positive PDO. In summary, the relation between PJ pattern and JJA Korean temperature and precipitation depends on subtropical precipitation's pattern. And The subtropical precipitation is effected by Indian SST and PDO's teleconnection.

Urban Heat Wave Hazard Assessment

NASA Astrophysics Data System (ADS)

Quattrochi, D. A.; Jedlovec, G.; Crane, D. L.; Meyer, P. J.; LaFontaine, F.

2016-12-01

Heat waves are one of the largest causes of environmentally-related deaths globally and are likely to become more numerous as a result of climate change. The intensification of heat waves by the urban heat island effect and elevated humidity, combined with urban demographics, are key elements leading to these disasters. Better warning of the potential hazards may help lower risks associated with heat waves. Moderate resolution thermal data from NASA satellites is used to derive high spatial resolution estimates of apparent temperature (heat index) over urban regions. These data, combined with demographic data, are used to produce a daily heat hazard/risk map for selected cities. MODIS data are used to derive daily composite maximum and minimum land surface temperature (LST) fields to represent the amplitude of the diurnal temperature cycle and identify extreme heat days. Compositing routines are used to generate representative daily maximum and minimum LSTs for the urban environment. The limited effect of relative humidity on the apparent temperature (typically 10-15%) allows for the use of modeled moisture fields to convert LST to apparent temperature without loss of spatial variability. The daily max/min apparent temperature fields are used to identify abnormally extreme heat days relative to climatological values in order to produce a heat wave hazard map. Reference to climatological values normalizes the hazard for a particular region (e.g., the impact of an extreme heat day). A heat wave hazard map has been produced for several case study periods and then computed on a quasi-operational basis during the summer of 2016 for Atlanta, GA, Chicago, IL, St. Louis, MO, and Huntsville, AL. A hazard does not become a risk until someone or something is exposed to that hazard at a level that might do harm. Demographic information is used to assess the urban risk associated with the heat wave hazard. Collectively, the heat wave hazard product can warn people in urban regions who do not have the means to provide air conditioning or take other means to stay cool. The heat wave risk product is conveyed to users via a website that describes current and historical heat wave information and is updated in real time as needed. These risk maps can be used for better monitoring of public health risk from extreme heat events in urban areas.

Thermal infrared sounding observations of lower atmospheric variances at Mars and their implications for gravity wave activity: a preliminary examination

NASA Astrophysics Data System (ADS)

Heavens, N. G.

2017-12-01

It has been recognized for over two decades that the mesoscale statistical variance observed by Earth-observing satellites at temperature-sensitive frequencies above the instrumental noise floor is a measure of gravity wave activity. These types of observation have been made by a variety of satellite instruments have been an important validation tool for gravity wave parameterizations in global and mesoscale models. At Mars, the importance of topographic and non-topographic sources of gravity waves for the general circulation is now widely recognized and the target of recent modeling efforts. However, despite several ingenious studies, gravity wave activity near hypothetical lower atmospheric sources has been poorly and unsystematically characterized, partly because of the difficulty of separating the gravity wave activity from baroclinic wave activity and the thermal tides. Here will be presented a preliminary analysis of calibrated radiance variance at 15.4 microns (635-665 cm-1) from nadir, off-nadir, and limb observations by the Mars Climate Sounder on board Mars Reconnaissance Orbiter. The overarching methodology follows Wu and Waters (1996, 1997). Nadir, off-nadir, and lowest detector limb observations should sample variability with vertical weighting functions centered high in the lower atmosphere (20-30 km altitude) and full width half maximum (FWHM) 20 km but be sensitive to gravity waves with different horizontal wavelengths and slightly different vertical wavelengths. This work is supported by NASA's Mars Data Analysis Program (NNX14AM32G). References Wu, D.L. and J.W. Waters, 1996, Satellite observations of atmospheric variances: A possible indication of gravity waves, GRL, 23, 3631-3634. Wu D.L. and J.W. Waters, 1997, Observations of Gravity Waves with the UARS Microwave Limb Sounder. In: Hamilton K. (eds) Gravity Wave Processes. NATO ASI Series (Series I: Environmental Change), vol 50. Springer, Berlin, Heidelberg.

Viscous, radiating hypersonic flow about a blunt body

NASA Technical Reports Server (NTRS)

Passamaneck, R. S.

1974-01-01

The viscous, radiating hypersonic flow past an axisymmetric blunt body is analyzed based on the Navier-Stokes equations, plus a radiative equation of transfer derived from the Milne-Eddington differential approximation. The fluid is assumed to be a perfect gas with constant specific heats, a constant Prandtl number of order unity, a viscosity coefficient varying as a power of the temperature, and an absorption coefficient varying as the first power of the density and as a power of the temperature. The gray gas assumption is invoked, thereby making the absorption coefficient independent of the spectral frequency. Limiting forms of the solutions are studied as the freestream Mach number freestream Reynolds number and the temperature ratio across the shock wave, go to infinity, and as the Bouguer number and the density ratio across the shock wave go to zero. The method of matched asymptotic expansions is used in the analysis, and it is shown that there is a far-field precursor, composed of two regions, in which the fluid mechanics can be neglected for all practical purposes but included for completeness.

Geophysical Analysis of Major Geothermal Anomalies in Romania

NASA Astrophysics Data System (ADS)

Panea, Ionelia; Mocanu, Victor

2017-11-01

The Romanian segment of the Eastern Pannonian Basin and the Moesian Platform are known for their geothermal and hydrocarbon-bearing structures. We used seismic, gravity, and geothermal data to analyze the geothermal behavior in the Oradea and Timisoara areas, from the Romanian segment of Eastern Pannonian Basin, and the Craiova-Bals-Optasi area, from the Moesian Platform. We processed 22 seismic reflection data sets recorded in the Oradea and Timisoara areas to obtain P-wave velocity distributions and time seismic sections. The P-wave velocity distributions correlate well with the structural trends observed along the seismic lines. We observed a good correlation between the high areas of crystalline basement seen on the time seismic sections and the high heat flow and gravity-anomaly values. For the Craiova-Bals-Optasi area, we computed a three-dimensional (3D) temperature model using calculated and measured temperature and geothermal gradient values in wells with an irregular distribution on the territory. The high temperatures from the Craiova-Bals-Optasi area correlate very well with the uplifted basement blocks seen on the time seismic sections and high gravity-anomaly values.

Joule Heating and Thermal Denaturation of Proteins in Nano-ESI Theta Tips

NASA Astrophysics Data System (ADS)

Zhao, Feifei; Matt, Sarah M.; Bu, Jiexun; Rehrauer, Owen G.; Ben-Amotz, Dor; McLuckey, Scott A.

2017-10-01

Electro-osmotically induced Joule heating in theta tips and its effect on protein denaturation were investigated. Myoglobin, equine cytochrome c, bovine cytochrome c, and carbonic anhydrase II solutions were subjected to electro-osmosis in a theta tip and all of the proteins were denatured during the process. The extent of protein denaturation was found to increase with the applied square wave voltage and electrolyte concentration. The solution temperature at the end of a theta tip was measured directly by Raman spectroscopy and shown to increase with the square wave voltage, thereby demonstrating the effect of Joule heating through an independent method. The electro-osmosis of a solution comprised of myoglobin, bovine cytochrome c, and ubiquitin demonstrated that the magnitude of Joule heating that causes protein denaturation is positively correlated with protein melting temperature. This allows for a quick determination of a protein's relative thermal stability. This work establishes a fast, novel method for protein conformation manipulation prior to MS analysis and provides a temperature-controllable platform for the study of processes that take place in solution with direct coupling to mass spectrometry. [Figure not available: see fulltext.

Ocean Wave Studies with Applications to Ocean Modeling and Improvement of Satellite Altimeter Measurements

NASA Technical Reports Server (NTRS)

Glazman, Roman E.

1999-01-01

Combining analysis of satellite data (altimeter, scatterometer, high-resolution visible and infrared images, etc.) with mathematical modeling of non-linear wave processes, we investigate various ocean wave fields (on scales from capillary to planetary), their role in ocean dynamics and turbulent transport (of heat and biogeochemical quantities), and their effects on satellite altimeter measuring accuracy. In 1998 my attention was focused on long internal gravity waves (10 to 1000 km), known also as baroclinic inertia-gravity (BIG) waves. We found these waves to be a major factor of altimeter measurements "noise," resulting in a greater uncertainty [up to 10 cm in terms of sea surface height (SSH) amplitude] in the measured SSH signal than that caused by the sea state bias variations (up to 5 cm or so). This effect still remains largely overlooked by the satellite altimeter community. Our studies of BIG waves address not only their influence on altimeter measurements but also their role in global ocean dynamics and in transport and turbulent diffusion of biogeochemical quantities. In particular, in collaboration with Prof Peter Weichman, Caltech, we developed a theory of turbulent diffusion caused by wave motions of most general nature. Applied to the problem of horizontal turbulent diffusion in the ocean, the theory yielded the effective diffusion coefficient as a function of BIG wave parameters obtainable from satellite altimeter data. This effort, begun in 1997, has been successfully completed in 1998. We also developed a theory that relates spatial fluctuations of scalar fields (such as sea surface temperature, chlorophyll concentration, drifting ice concentration, etc.) to statistical characteristics of BIG waves obtainable from altimeter measurements. A manuscript is in the final stages of preparation. In order to verify the theoretical predictions and apply them to observations, we are now analyzing Sea-viewing Wide Field of view Sensor (SeaWiFS) and Field of view Sensor (SeaWiFS) and Advanced Very High-Resolution Radiometer (AVHRR) data on sea surface temperature (SST) and chlorophyll concentration jointly with TOPEX/POSEIDON data on SSH variations.

Phase fluctuations in a strongly disordered s-wave NbN superconductor close to the metal-insulator transition.

PubMed

Mondal, Mintu; Kamlapure, Anand; Chand, Madhavi; Saraswat, Garima; Kumar, Sanjeev; Jesudasan, John; Benfatto, L; Tripathi, Vikram; Raychaudhuri, Pratap

2011-01-28

We explore the role of phase fluctuations in a three-dimensional s-wave superconductor, NbN, as we approach the critical disorder for destruction of the superconducting state. Close to critical disorder, we observe a finite gap in the electronic spectrum which persists at temperatures well above T(c). The superfluid density is strongly suppressed at low temperatures and evolves towards a linear-T variation at higher temperatures. These observations provide strong evidence that phase fluctuations play a central role in the formation of a pseudogap state in a disordered s-wave superconductor.

Stable indications of relic gravitational waves in Wilkinson Microwave Anisotropy Probe data and forecasts for the Planck mission

NASA Astrophysics Data System (ADS)

Zhao, W.; Baskaran, D.; Grishchuk, L. P.

2009-10-01

The relic gravitational waves are the cleanest probe of the violent times in the very early history of the Universe. They are expected to leave signatures in the observed cosmic microwave background anisotropies. We significantly improved our previous analysis [W. Zhao, D. Baskaran, and L. P. Grishchuk, Phys. Rev. DPRVDAQ1550-7998 79, 023002 (2009)10.1103/PhysRevD.79.023002] of the 5-year WMAP TT and TE data at lower multipoles ℓ. This more general analysis returned essentially the same maximum likelihood result (unfortunately, surrounded by large remaining uncertainties): The relic gravitational waves are present and they are responsible for approximately 20% of the temperature quadrupole. We identify and discuss the reasons by which the contribution of gravitational waves can be overlooked in a data analysis. One of the reasons is a misleading reliance on data from very high multipoles ℓ and another a too narrow understanding of the problem as the search for B modes of polarization, rather than the detection of relic gravitational waves with the help of all correlation functions. Our analysis of WMAP5 data has led to the identification of a whole family of models characterized by relatively high values of the likelihood function. Using the Fisher matrix formalism we formulated forecasts for Planck mission in the context of this family of models. We explore in detail various “optimistic,” “pessimistic,” and “dream case” scenarios. We show that in some circumstances the B-mode detection may be very inconclusive, at the level of signal-to-noise ratio S/N=1.75, whereas a smarter data analysis can reveal the same gravitational wave signal at S/N=6.48. The final result is encouraging. Even under unfavorable conditions in terms of instrumental noises and foregrounds, the relic gravitational waves, if they are characterized by the maximum likelihood parameters that we found from WMAP5 data, will be detected by Planck at the level S/N=3.65.

Transient thermal stress wave and vibrational analyses of a thin diamond crystal for X-ray free-electron lasers under high-repetition-rate operation

DOE PAGES

Yang, Bo; Wang, Songwei; Wu, Juhao

2018-01-01

High-brightness X-ray free-electron lasers (FELs) are perceived as fourth-generation light sources providing unprecedented capabilities for frontier scientific researches in many fields. Thin crystals are important to generate coherent seeds in the self-seeding configuration, provide precise spectral measurements, and split X-ray FEL pulses, etc. In all of these applications a high-intensity X-ray FEL pulse impinges on the thin crystal and deposits a certain amount of heat load, potentially impairing the performance. In the present paper, transient thermal stress wave and vibrational analyses as well as transient thermal analysis are carried out to address the thermomechanical issues for thin diamond crystals, especiallymore » under high-repetition-rate operation of an X-ray FEL. The material properties at elevated temperatures are considered. It is shown that, for a typical FEL pulse depositing tens of microjoules energy over a spot of tens of micrometers in radius, the stress wave emission is completed on the tens of nanoseconds scale. The amount of kinetic energy converted from a FEL pulse can reach up to ~10 nJ depending on the layer thickness. Natural frequencies of a diamond plate are also computed. The potential vibrational amplitude is estimated as a function of frequency. Here, due to the decreasing heat conductivity with increasing temperature, a runaway temperature rise is predicted for high repetition rates where the temperature rises abruptly after ratcheting up to a point of trivial heat damping rate relative to heat deposition rate.« less

Transient thermal stress wave and vibrational analyses of a thin diamond crystal for X-ray free-electron lasers under high-repetition-rate operation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Bo; Wang, Songwei; Wu, Juhao

High-brightness X-ray free-electron lasers (FELs) are perceived as fourth-generation light sources providing unprecedented capabilities for frontier scientific researches in many fields. Thin crystals are important to generate coherent seeds in the self-seeding configuration, provide precise spectral measurements, and split X-ray FEL pulses, etc. In all of these applications a high-intensity X-ray FEL pulse impinges on the thin crystal and deposits a certain amount of heat load, potentially impairing the performance. In the present paper, transient thermal stress wave and vibrational analyses as well as transient thermal analysis are carried out to address the thermomechanical issues for thin diamond crystals, especiallymore » under high-repetition-rate operation of an X-ray FEL. The material properties at elevated temperatures are considered. It is shown that, for a typical FEL pulse depositing tens of microjoules energy over a spot of tens of micrometers in radius, the stress wave emission is completed on the tens of nanoseconds scale. The amount of kinetic energy converted from a FEL pulse can reach up to ~10 nJ depending on the layer thickness. Natural frequencies of a diamond plate are also computed. The potential vibrational amplitude is estimated as a function of frequency. Here, due to the decreasing heat conductivity with increasing temperature, a runaway temperature rise is predicted for high repetition rates where the temperature rises abruptly after ratcheting up to a point of trivial heat damping rate relative to heat deposition rate.« less

Transient thermal stress wave and vibrational analyses of a thin diamond crystal for X-ray free-electron lasers under high-repetition-rate operation.

PubMed

Yang, Bo; Wang, Songwei; Wu, Juhao

2018-01-01

High-brightness X-ray free-electron lasers (FELs) are perceived as fourth-generation light sources providing unprecedented capabilities for frontier scientific researches in many fields. Thin crystals are important to generate coherent seeds in the self-seeding configuration, provide precise spectral measurements, and split X-ray FEL pulses, etc. In all of these applications a high-intensity X-ray FEL pulse impinges on the thin crystal and deposits a certain amount of heat load, potentially impairing the performance. In the present paper, transient thermal stress wave and vibrational analyses as well as transient thermal analysis are carried out to address the thermomechanical issues for thin diamond crystals, especially under high-repetition-rate operation of an X-ray FEL. The material properties at elevated temperatures are considered. It is shown that, for a typical FEL pulse depositing tens of microjoules energy over a spot of tens of micrometers in radius, the stress wave emission is completed on the tens of nanoseconds scale. The amount of kinetic energy converted from a FEL pulse can reach up to ∼10 nJ depending on the layer thickness. Natural frequencies of a diamond plate are also computed. The potential vibrational amplitude is estimated as a function of frequency. Due to the decreasing heat conductivity with increasing temperature, a runaway temperature rise is predicted for high repetition rates where the temperature rises abruptly after ratcheting up to a point of trivial heat damping rate relative to heat deposition rate.

Do Heat Waves have an Impact on Terrestrial Water Storage?

NASA Astrophysics Data System (ADS)

Brena-Naranjo, A.; Teuling, R.; Pedrozo-Acuña, A.

2014-12-01

Recent works have investigated the impact of heat waves on the surface energy and carbon balance. However, less attention has been given to the impacts on terrestrial hydrology. During the summer of 2010, the occurrence of an exceptional heat wave affected severely the Northern Hemisphere. The extension (more than 2 million km2) and severity of this extreme event caused substantial ecosystem damage (more than 1 million ha of forest fires), economic and human losses (~500 billion USD and more than 17 million of indirect deaths, respectively). This work investigates for the first time the impacts of the 2010 summer heat wave on terrestrial water storage. Our study area comprises three different regions where air temperature records were established or almost established during the summer: Western Russia, the Middle East and Eastern Sahel. Anomalies of terrestrial water storage derived from the Gravity Recovery and Climate Experiment (GRACE) were used to infer water storage deficits during the 2003-2013 period. Our analysis shows that Russia experienced the most severe water storage decline, followed by the Middle East, whereas Eastern Sahel was not significantly affected. The impact of the heat wave was spatially uniform in Russia but highly variable in the Middle East, with the Northern part substantially more affected than the Southern region. Lag times between maxima air temperatures and lower water storage deficits for Russia and the Middle East were approximately two and seven months, respectively. The results suggest that the response of terrestrial water storage to heat waves is stronger in energy-limited environments than in water-limited regions. Such differences in the magnitude and timing between meteorological and hydrological extremes can be explained by the propagation time between atmospheric water demand and natural or anthropogenic sources of water storage.

Plasma waves at comet 67P/Churyumov-Gerasimenko: in the diamagnetic cavity and outside it

NASA Astrophysics Data System (ADS)

Gunell, Herbert; Altwegg, Kathrin; Cessateur, Gaël; De Keyser, Johan; Dhooghe, Frederik; Eriksson, Anders; Gibbons, Andrew; Glassmeier, Karl-Heinz; Goetz, Charlotte; Karlsson, Tomas; Hamrin, Maria; Henri, Pierre; Maggiolo, Romain; Nilsson, Hans; Odelstad, Elias; Rubin, Martin; Wedlund, Cyril Simon; Stenberg Wieser, Gabriella; Tzou, Chia-Yu; Vallieres, Xavier

2017-04-01

We present observations of waves at Comet 67P/Churyumov-Gerasimenko performed on 20 January 2015, when the activity of the comet was low, and in July and August 2015 when the activity had increased and the Rosetta spacecraft passed through the diamagnetic cavity several times. We use distribution functions obtained by the Ion Composition Analyser of the Rosetta Plasma Consortium (RPC-ICA) and electron temperature estimates from the Langmuir Probes (RPC-LAP) to compute dispersion relations for waves on the ion timescale, and we compare the results to spectra obtained by RPC-LAP. On 20 January 2015, at low activity, peaks of the wave spectra appeared at frequencies near 500 Hz, and we identify these waves as ion acoustic. We performed cross-calibrations between RPC-ICA, RPC-LAP, and the Mutual Impedance Probe (RPC-MIP) in order to determine the plasma density. Matching the dispersion relations to the wave observations also helps us estimating the density. We explore the relationship between the waves, the ion distribution functions, and the neutral density, which was measured by the ROSINA-COPS instrument. It is found that when the waves are seen, the ion temperature is low (approximately 0.01 eV). At times the ion temperature is higher (approximately 1 eV), approaching the electron temperature, which leads to strong damping of the ion acoustic waves. This happens when the neutral density is high, suggesting that the ions are heated by being accelerated by the solar wind electric field and scattered in collisions with the neutrals. These results are compared to measurements of wave spectra when Rosetta was inside the diamagnetic cavity in July and August 2015. In the cavity, the plasma is effectively unmagnetised. We identify cavity passages using the magnetometer RPC-MAG. The waves are analysed in the same way as in the earlier measurements outside the cavity, and the two cases are compared.

A coordinated study of 1 h mesoscale gravity waves propagating from Logan to Boulder with CRRL Na Doppler lidars and temperature mapper

NASA Astrophysics Data System (ADS)

Lu, Xian; Chen, Cao; Huang, Wentao; Smith, John A.; Chu, Xinzhao; Yuan, Tao; Pautet, Pierre-Dominique; Taylor, Mike J.; Gong, Jie; Cullens, Chihoko Y.

2015-10-01

We present the first coordinated study using two lidars at two separate locations to characterize a 1 h mesoscale gravity wave event in the mesopause region. The simultaneous observations were made with the Student Training and Atmospheric Research (STAR) Na Doppler lidar at Boulder, CO, and the Utah State University Na Doppler lidar and temperature mapper at Logan, UT, on 27 November 2013. The high precision possessed by the STAR lidar enabled these waves to be detected in vertical wind. The mean wave amplitudes are ~0.44 m/s in vertical wind and ~1% in relative temperature at altitudes of 82-107 km. Those in the zonal and meridional winds are 6.1 and 5.2 m/s averaged from 84 to 99 km. The horizontal and vertical wavelengths inferred from the mapper and lidars are ~219 ± 4 and 16.0 ± 0.3 km, respectively. The intrinsic period is ~1.3 h for the airglow layer, Doppler shifted by a mean wind of ~17 m/s. The wave packet propagates from Logan to Boulder with an azimuth angle of ~135° clockwise from north and an elevation angle of ~ 3° from the horizon. The observed phase difference between the two locations can be explained by the traveling time of the 1 h wave from Logan to Boulder, which is about ~2.4 h. The wave polarization relations are examined through the simultaneous quantifications of the three wind components and temperature. This study has developed a systematic methodology for fully characterizing mesoscale gravity waves, inspecting their intrinsic properties and validating the derivation of horizontal wave structures by applying multiple instruments from coordinated stations.

Modeling temperature inversion in southeastern Yellow Sea during winter 2016

NASA Astrophysics Data System (ADS)

Pang, Ig-Chan; Moon, Jae-Hong; Lee, Joon-Ho; Hong, Ji-Seok; Pang, Sung-Jun

2017-05-01

A significant temperature inversion with temperature differences larger than 3°C was observed in the southeastern Yellow Sea (YS) during February 2016. By analyzing in situ hydrographic profiles and results from a regional ocean model for the YS, this study examines the spatiotemporal evolution of the temperature inversion and its connection with wind-induced currents in winter. Observations reveal that in winter, when the northwesterly wind prevails over the YS, the temperature inversion occurs largely at the frontal zone southwest of Korea where warm/saline water of a Kuroshio origin meets cold/fresh coastal water. Our model successfully captures the temperature inversion observed in the winter of 2016 and suggests a close relation between northwesterly wind bursts and the occurrence of the large inversion. In this respect, the strong northwesterly wind drove cold coastal water southward in the upper layer via Ekman transport, which pushed the water mass southward and increased the sea level slope in the frontal zone in southeastern YS. The intensified sea level slope propagated northward away from the frontal zone as a shelf wave, causing a northward upwind flow response along the YS trough in the lower layer, thereby resulting in the large temperature inversion. Diagnostic analysis of the momentum balance shows that the westward pressure gradient, which developed with shelf wave propagation along the YS trough, was balanced with the Coriolis force in accordance with the northward upwind current in and around the inversion area.

Comparison of transient measurements of infrared radiation and stress waves for practical ablation monitoring during photorefractive keratectomy

NASA Astrophysics Data System (ADS)

Ishihara, Miya; Arai, Tsunenori; Kikuchi, Makoto; Nakano, Hironori; Kawauchi, Satoko; Obara, Minoru

1998-05-01

We compared infrared radiation measurement with stress wave measurement for real-time ablation monitoring during photorefractive keratectomy (PRK). We estimated temperature elevation which may be one of the most effective parameter for PRK monitoring, because the ablation mechanism is mainly attributed to thermal kinetics. The temperature elevation of ablated cornea was evaluated by the infrared radiation and the stress wave. The thermal radiation from irradiated cornea was detected by a MCT detector. The measured signal increased sharply just after the laser irradiation and decreased quasi- exponentially. We could calculate the temperature elevation by observed signal using Stefan-Boltzmann radiation law. In the case of the gelatin gel (15% wt) ablation in vitro, the temperature elevation was 97 deg. at 208 mJ/cm2 in the laser fluence. We also measured transient stress wave by the acoustic transducer which was made by polyvinylidene fluoride (PVDF) film. The temperature elevation could be calculated from the peak stress amplitude based on the short pulsed laser ablation theory. The good agreement on the temperature elevation was obtained between the infrared and the stress based estimations. Due to non-contact and non-invasive method, our infrared measurements for temperature elevation monitoring may be available to accomplish the feedback control on the PRK.

Subseasonal prediction of the heat wave of December 2013 in Southern South America by the POAMA and BCC-CPS models

NASA Astrophysics Data System (ADS)

Osman, Marisol; Alvarez, Mariano S.

2018-01-01

The prediction skill of subseasonal forecast models is evaluated for a strong and long-lasting heat wave occurred in December 2013 over Southern South America. Reforecasts from two models participating in the WCRP/WWRP Subseasonal to Seasonal project, the Bureau of Meteorology POAMA and Beijing Climate Center model BCC-CPS were considered to evaluate their skill in forecasting temperature and circulation anomalies during that event. The POAMA reforecast of 32-member ensemble size, initialized every five days, and BCC-CPS reforecast of 4-member ensemble size for the same date of POAMA plus the previous 4 days were considered. Weekly ensemble-mean forecasts were computed with leadtimes from 2 days up to 24 days every 5 days. Weekly anomalies were calculated for observations from 13th of December to 31st of December 2013. Anomalies for both observations and reforecast were calculated with respect to their own climatology. Results show that the ensemble mean warm anomalies forecasted for week 1 and 2 of the heat wave resulted more similar to the observations for the POAMA model, especially for longer leads. The BCC-CPS performed better for leads shorter than 7 (14) for week 1 (2). For week 3 the BCC-CPS outperformed the POAMA model, particularly at shorter leads, locating more accurately the maxima of the anomalies. In a probabilistic approach, POAMA predicted with a higher chance than BCC-CPS the excess of the upper tercile of temperature anomalies for almost every week and lead time. The forecast of the circulation anomalies over South America could be used to explain the location of the highest temperature anomalies. In summary, for this case, models skill in forecasting surface temperature in a context of a heat wave resulted moderate at lead times longer than the fortnight. However, this study is limited to model-to-model analysis and a multi-model ensemble strategy might increase the skill.

Humid Heat Waves at different warming levels

NASA Astrophysics Data System (ADS)

Russo, S.; Sillmann, J.; Sterl, A.

2017-12-01

The co-occurrence of consecutive hot and humid days during a heat wave can strongly affect human health. Here, we quantify humid heat wave hazard in the recent past and at different levels of global warming.We find that the magnitude and apparent temperature peak of heat waves, such as the ones observed in Chicago in 1995 and China in 2003, have been strongly amplified by humidity. Climate model projections suggest that the percentage of area where heat wave magnitude and peak are amplified by humidity increases with increasing warming levels. Considering the effect of humidity at 1.5o and 2o global warming, highly populated regions, such as the Eastern US and China, could experience heat waves with magnitude greater than the one in Russia in 2010 (the most severe of the present era).The apparent temperature peak during such humid-heat waves can be greater than 55o. According to the US Weather Service, at this temperature humans are very likely to suffer from heat strokes. Humid-heat waves with these conditions were never exceeded in the present climate, but are expected to occur every other year at 4o global warming. This calls for respective adaptation measures in some key regions of the world along with international climate change mitigation efforts.

The Coordinated Ocean Wave Climate Project

NASA Astrophysics Data System (ADS)

Hemer, Mark; Dobrynin, Mikhail; Erikson, Li; Lionello, Piero; Mori, Nobuhito; Semedo, Alvaro; Wang, Xiaolan

2016-04-01

Future 21st Century changes in wind-wave climate have broad implications for marine and coastal infrastructure and ecosystems. Atmosphere-ocean general circulation models (GCM) are now routinely used for assessing and providing future projections of climatological parameters such as temperature and precipitation, but generally these provide no information on ocean wind-waves. To fill this information gap a growing number of studies are using GCM outputs and independently producing global and regional scale wind-wave climate projections. Furthermore, additional studies are actively coupling wind-wave dependent atmosphere-ocean exchanges into GCMs, to improve physical representation and quantify the impact of waves in the coupled climate system, and can also deliver wave characteristics as another variable in the climate system. To consolidate these efforts, understand the sources of variance between projections generated by different methodologies and International groups, and ultimately provide a robust picture of the role of wind-waves in the climate system and their projected changes, we present outcomes of the JCOMM supported Coordinated Ocean Wave Climate Project (COWCLIP). The objective of COWCLIP is twofold: to make community based ensembles of wave climate projections openly accessible, to provide the necessary information to support diligent marine and coastal impacts of climate change studies; and to understand the effects and feedback influences of wind-waves in the coupled ocean-atmosphere climate system. We will present the current status of COWCLIP, providing an overview of the objectives, analysis and results of the initial phase - now complete - and the progress of ongoing phases of the project.

Wave energetics of the southern hemisphere of Mars

NASA Astrophysics Data System (ADS)

Battalio, Michael; Szunyogh, Istvan; Lemmon, Mark

2018-07-01

An assessment of the energetics of transient waves in the southern hemisphere of Mars is presented using the Mars Analysis Correction Data Assimilation (MACDA) dataset (v1.0) and the eddy kinetic energy equation. The dataset is divided into four representative periods covering the summer and winter solstices, a late fall period, and an early spring period for three Mars years. Spring eddies are the most intense, with eddies during the fall being less intense due to a marginally more stable mean-temperature profile and reduced recirculation of ageostrophic geopotential fluxes compared to the spring. Eddy kinetic energy during winter is reduced in intensity as a result of the winter solstitial pause in wave activity, and eddy kinetic energy during the summer is limited. Baroclinic energy conversion acts as a source in fall and spring but disappears during the winter as a result of a stabilized vertical temperature profile. Barotropic energy conversion acts as both a source and a sink of eddy kinetic energy, being most positive during the solstitial pause. Eddies take a northwest to southeast track across the southern highlands in the fall but have a more zonal track in the spring due to stronger eddy kinetic energy advection. Wave energetics is less intense in the southern compared to the northern hemisphere as a result of a shallower baroclinically unstable vertical profile.

Kinetic water-bag model of global collisional drift waves and ion temperature gradient instabilities in cylindrical geometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gravier, E.; Plaut, E.

2013-04-15

Collisional drift waves and ion temperature gradient (ITG) instabilities are studied using a linear water-bag kinetic model [P. Morel et al., Phys. Plasmas 14, 112109 (2007)]. An efficient spectral method, already validated in the case of drift waves instabilities [E. Gravier et al., Eur. Phys. J. D 67, 7 (2013)], allows a fast solving of the global linear problem in cylindrical geometry. The comparison between the linear ITG instability properties thus computed and the ones given by the COLUMBIA experiment [R. G. Greaves et al., Plasma Phys. Controlled Fusion 34, 1253 (1992)] shows a qualitative agreement. Moreover, the transition betweenmore » collisional drift waves and ITG instabilities is studied theoretically as a function of the ion temperature profile.« less

The Temperature of the Arctic and Antarctic Lower Stratosphere

NASA Technical Reports Server (NTRS)

Newman, Paul A.; Nash, Eric R.; Bhartia, P. K. (Technical Monitor)

2002-01-01

The temperature of the polar lower stratosphere during spring is the key factor in changing the magnitude of ozone loss in the polar vortices. In this talk, we will review the results of Newman et al. [2000] that quantitatively demonstrate that the polar lower stratospheric temperature is primarily controlled by planetary-scale waves. In particular, the tropospheric eddy heat flux in middle to late winter (January--February) is highly correlated with the mean polar stratospheric temperature during March. Strong midwinter planetary wave forcing leads to a warmer spring Arctic lower stratosphere in early spring, while weak midwinter forcing leads to cooler spring Arctic temperatures. In addition, this planetary wave driving also has a strong impact on the strength of the polar vortex. These results from the Northern Hemisphere will be contrasted with the Southern Hemisphere.

Traveling-wave induction launchers

NASA Technical Reports Server (NTRS)

Elliott, David G.

1989-01-01

An analysis of traveling-wave induction launchers shows that induction is a feasible method of producing armature current and that efficient accelerators can be built without sliding contacts or arcs. In a traveling-wave induction launcher the armature current is induced by a slip speed between the armature and a traveling magnetic field. At 9 m/s slip speed a 9 kg projectile with an aluminum armature weighing 25 percent of the total mass can be accelerated to 3000 m/s in a 5 m-long barrel with a total ohmic loss in the barrel coils and armature of 4 percent of the launch kinetic energy and with an average armature temperature rise of 220 deg C, but a peak excitation frequency of 8600 Hz is required. With a 2 kg launch mass the ohmic loss is 7 percent. A launcher system optimized for rotating generators would have a peak frequency of 4850 Hz; with an aluminum armature weighing 33 percent of the launch mass and a slip speed of 30 m/s the total ohmic loss in the generators, cables, and accelerator would be 43 percent of the launch kinetic energy, and the average armature temperature rise would be 510 deg C.

Local heat stroke prevention plans in Japan: characteristics and elements for public health adaptation to climate change.

PubMed

Martinez, Gerardo Sanchez; Imai, Chisato; Masumo, Kanako

2011-12-01

The adverse health effects from hot weather and heat waves represent significant public health risks in vulnerable areas worldwide. Rising temperatures due to climate change are aggravating these risks in a context of fast urbanization, population growth and societal ageing. However, environmental heat-related health effects are largely preventable through adequate preparedness and responses. Public health adaptation to climate change will often require the implementation of heat wave warning systems and targeted preventive activities at different levels. While several national governments have established such systems at the country level, municipalities do not generally play a major role in the prevention of heat disorders. This paper analyzes selected examples of locally operated heat-health prevention plans in Japan. The analysis of these plans highlights their strengths, but also the need of local institutions for assistance to make the transition towards an effective public health management of high temperatures and heat waves. It can also provide useful elements for municipal governments in vulnerable areas, both in planning their climate change and health adaptation activities or to better protect their communities against current health effects from heat.

Local Heat Stroke Prevention Plans in Japan: Characteristics and Elements for Public Health Adaptation to Climate Change

PubMed Central

Martinez, Gerardo Sanchez; Imai, Chisato; Masumo, Kanako

2011-01-01

The adverse health effects from hot weather and heat waves represent significant public health risks in vulnerable areas worldwide. Rising temperatures due to climate change are aggravating these risks in a context of fast urbanization, population growth and societal ageing. However, environmental heat-related health effects are largely preventable through adequate preparedness and responses. Public health adaptation to climate change will often require the implementation of heat wave warning systems and targeted preventive activities at different levels. While several national governments have established such systems at the country level, municipalities do not generally play a major role in the prevention of heat disorders. This paper analyzes selected examples of locally operated heat-health prevention plans in Japan. The analysis of these plans highlights their strengths, but also the need of local institutions for assistance to make the transition towards an effective public health management of high temperatures and heat waves. It can also provide useful elements for municipal governments in vulnerable areas, both in planning their climate change and health adaptation activities or to better protect their communities against current health effects from heat. PMID:22408589

Numerical modeling of a multiscale gravity wave event and its airglow signatures over Mount Cook, New Zealand, during the DEEPWAVE campaign

NASA Astrophysics Data System (ADS)

Heale, C. J.; Bossert, K.; Snively, J. B.; Fritts, D. C.; Pautet, P.-D.; Taylor, M. J.

2017-01-01

A 2-D nonlinear compressible model is used to simulate a large-amplitude, multiscale mountain wave event over Mount Cook, NZ, observed as part of the Deep Propagating Gravity Wave Experiment (DEEPWAVE) campaign and to investigate its observable signatures in the hydroxyl (OH) layer. The campaign observed the presence of a λx=200 km mountain wave as part of the 22nd research flight with amplitudes of >20 K in the upper stratosphere that decayed rapidly at airglow heights. Advanced Mesospheric Temperature Mapper (AMTM) showed the presence of small-scale (25-28 km) waves within the warm phase of the large mountain wave. The simulation results show rapid breaking above 70 km altitude, with the preferential formation of almost-stationary vortical instabilities within the warm phase front of the mountain wave. An OH airglow model is used to identify the presence of small-scale wave-like structures generated in situ by the breaking of the mountain wave that are consistent with those seen in the observations. While it is easy to interpret these feature as waves in OH airglow data, a considerable fraction of the features are in fact instabilities and vortex structures. Simulations suggest that a combination of a large westward perturbation velocity and shear, in combination with strong perturbation temperature gradients, causes both dynamic and convective instability conditions to be met particularly where the wave wind is maximized and the temperature gradient is simultaneously minimized. This leads to the inevitable breaking and subsequent generation of smaller-scale waves and instabilities which appear most prominent within the warm phase front of the mountain wave.

Influence of changing surface temperature gradients on mid-latitudinal circulation and western hemispheric summer temperature extremes

NASA Astrophysics Data System (ADS)

Kornhuber, Kai; Hoffmann, Peter; Coumou, Dim

2017-04-01

Many recent summers in the Northern hemisphere (NH) mid-latitudes have seen severe heatwaves (2003, 2004, 2009, 2010, 2012, 2015, (Black et al. 2004; Diffenbaugh & Scherer 2013; Russo et al. 2014; Hoy et al. 2016)). During many of those extremes the mid-latitudinal tropospheric circulation was characterized by an amplified, quasi-stationary and hemispheric wave pattern with a dominant influence of wavenumber seven (Coumou et al. 2014; Petoukhov et al. 2016; Kornhuber et al. 2016). Analyzing NH summer reanalysis data we show that the position where these heat extremes occur is not arbitrary. If the amplitude of wave seven is large, the wave gets "locked" in a specific preferred phase position. As a consequence of this phase-locking behavior some regions are more likely to experience extreme weather during high-amplitude events. Meridional wind speeds associated with the preferred phase are particularly strong over longitudes of the western hemisphere (180°W - 40°E) leading to positive temperature anomalies over the US and Western Europe. Using a widely-used blocking-index we demonstrate that longitudes over these regions experience an increased probability of blocking during high amplitude wave seven events. We show that during the above mentioned extreme summers, amplified waves were locked in their preferred phase-position creating the right dynamical background condition for severe heatwaves to occur. Further, regression analyses reveal that a pronounced Ocean - Land temperature contrast (Tdiff) and weak poleward surface temperature gradient (dT/dy) are associated with an amplified wave seven in its preferred phase-position. Our study suggests that the observed positive trend in Tdiff and negative trend in dT/dy favors the occurrence of high-amplitude, quasi-stationary wave seven in its preferred phase position and therefore persistent heatwaves in the US and western Europe.

The Association Between Heat Waves and Other Meteorological Parameters and Snakebites: Israel National Study.

PubMed

Shashar, Sagi; Yitshak-Sade, Maayan; Sonkin, Roman; Novack, Victor; Jaffe, Eli

2018-06-01

Published annual estimates report a global burden of 2.5 million snakebite cases and >100,000 deaths. In Israel, envenomations are the third most frequent cause of poisonings that are of moderate to major clinical severity. Most studies focus on the clinical descriptions of snakebites in tropical climates, and we sought to investigate the association between snakebite frequency and meteorological parameters. We sought to investigate the seasonality of snakebites and evaluate the association between increasingly common heat waves and other meteorological parameters and snakebite frequency in a semiarid nontropical climate. We obtained data for all medical evacuations (2008-2015) because of snakebites in Israel. Climate data included daily 24-hour average temperature (°C) and relative humidity (%). We used a time-stratified case crossover method, in which a conditional logistic regression was applied to estimate the association, and we also stratified our analysis by season and by region. We identified 1234 snakebite cases over 8 years, of which most (74.2%) occurred in hot seasons and between 6 pm and 9 pm. The risk of snakebite was positively associated with temperature >23°C (odds ratio [OR] 1.24, 95% confidence interval [CI] 1.01-1.53) and inversely with humidity >40% (OR 0.74, 95% CI 0.57-0.97). We also found an association with heat waves both in cold (OR 1.62, 95% CI 1.01-2.60) and hot seasons (OR 1.50, 95% CI 1.18-1.92). In a semiarid nontropical climate, we observed an association between an increase in the number of snakebite cases and higher temperatures and lower humidity. Moreover, heat waves increased the frequency of snakebites in both cold and hot seasons. Copyright © 2018 Elsevier Inc. All rights reserved.

High Strain Rate and Shock-Induced Deformation in Metals

NASA Astrophysics Data System (ADS)

Ravelo, Ramon

2012-02-01

Large-scale non-equilibrium molecular Dynamics (MD) simulations are now commonly used to study material deformation at high strain rates (10^9-10^12 s-1). They can provide detailed information-- such as defect morphology, dislocation densities, and temperature and stress profiles, unavailable or hard to measure experimentally. Computational studies of shock-induced plasticity and melting in fcc and bcc single, mono-crystal metals, exhibit generic characteristics: high elastic limits, large directional anisotropies in the yield stress and pre-melting much below the equilibrium melt temperature for shock wave propagation along specific crystallographic directions. These generic features in the response of single crystals subjected to high strain rates of deformation can be explained from the changes in the energy landscape of the uniaxially compressed crystal lattice. For time scales relevant to dynamic shock loading, the directional-dependence of the yield strength in single crystals is shown to be due to the onset of instabilities in elastic-wave propagation velocities. The elastic-plastic transition threshold can accurately be predicted by a wave-propagation stability analysis. These strain-induced instabilities create incipient defect structures, which can be quite different from the ones, which characterize the long-time, asymptotic state of the compressed solid. With increase compression and strain rate, plastic deformation via extended defects gives way to amorphization associated with the loss in shear rigidity along specific deformation paths. The hot amorphous or (super-cooled liquid) metal re-crystallizes at rates, which depend on the temperature difference between the amorphous solid and the equilibrium melt line. This plastic-amorphous transition threshold can be computed from shear-waves stability analyses. Examples from selected fcc and bcc metals will be presented employing semi-empirical potentials of the embedded atom method (EAM) type as well as results from density functional theory calculations.

Changes in cause-specific mortality during heat waves in central Spain, 1975-2008

NASA Astrophysics Data System (ADS)

Miron, Isidro Juan; Linares, Cristina; Montero, Juan Carlos; Criado-Alvarez, Juan Jose; Díaz, Julio

2015-09-01

The relationship between heat waves and mortality has been widely described, but there are few studies using long daily data on specific-cause mortality. This study is undertaken in central Spain and analysing natural causes, circulatory and respiratory causes of mortality from 1975 to 2008. Time-series analysis was performed using ARIMA models, including data on specific-cause mortality and maximum and mean daily temperature and mean daily air pressure. The length of heat waves and their chronological number were analysed. Data were stratified in three decadal stages: 1975-1985, 1986-1996 and 1997-2008. Heat-related mortality was triggered by a threshold temperature of 37 °C. For each degree that the daily maximum temperature exceeded 37 °C, the percentage increase in mortality due to circulatory causes was 19.3 % (17.3-21.3) in 1975-1985, 30.3 % (28.3-32.3) in 1986-1996 and 7.3 % (6.2-8.4) in 1997-2008. The increase in respiratory cause ranged from 12.4 % (7.8-17.0) in the first period, to 16.3 % (14.1-18.4) in the second and 13.7 % (11.5-15.9) in the last. Each day of heat-wave duration explained 5.3 % (2.6-8.0) increase in respiratory mortality in the first period and 2.3 % (1.6-3.0) in the last. Decadal scale differences exist for specific-causes mortality induced by extreme heat. The impact on heat-related mortality by natural and circulatory causes increases between the first and the second period and falls significantly in the last. For respiratory causes, the increase is no reduced in the last period. These results are of particular importance for the estimation of future impacts of climate change on health.

Enhanced Climatic Warming in the Tibetan Plateau Due to Double CO2: A Model Study

NASA Technical Reports Server (NTRS)

Chen, Baode; Chao, Winston C.; Liu, Xiao-Dong; Lau, William K. M. (Technical Monitor)

2001-01-01

The NCAR (National Center for Atmospheric Research) regional climate model (RegCM2) with time-dependent lateral meteorological fields provided by a 130-year transient increasing CO2 simulation of the NCAR Climate System Model (CSM) has been used to investigate the mechanism of enhanced ground temperature warming over the TP (Tibetan Plateau). From our model results, a remarkable tendency of warming increasing with elevation is found for the winter season, and elevation dependency of warming is not clearly recognized in the summer season. This simulated feature of elevation dependency of ground temperature is consistent with observations. Based on an analysis of surface energy budget, the short wave solar radiation absorbed at the surface plus downward long wave flux reaching the surface shows a strong elevation dependency, and is mostly responsible for enhanced surface warming over the TP. At lower elevations, the precipitation forced by topography is enhanced due to an increase in water vapor supply resulted from a warming in the atmosphere induced by doubling CO2. This precipitation enhancement must be associated with an increase in clouds, which results in a decline in solar flux reaching surface. At higher elevations, large snow depletion is detected in the 2xCO2run. It leads to a decrease in albedo, therefore more solar flux is absorbed at the surface. On the other hand, much more uniform increase in downward long wave flux reaching the surface is found. The combination of these effects (i.e. decrease in solar flux at lower elevations, increase in solar flux at higher elevation and more uniform increase in downward long wave flux) results in elevation dependency of enhanced ground temperature warming over the TP.

New Experimental Setup for High-Pressure High-Temperature Gigahertz Ultrasonic Interferometry

NASA Astrophysics Data System (ADS)

Kantor, A. P.; Kantor, I. Y.; Dubrovinsky, L. S.; Jacobsen, S. D.

2005-12-01

The only direct information about Earth's interior comes from seismological observations of sound wave velocities. In order to create compositional and mineralogical model from seismological data knowledge of the elastic properties and crystal chemistry of minerals is necessary. Gigahertz ultrasonic interferometry (GUI) is a relatively new tool used to measure single-crystal compressional and shear-wave travel times, which are converted to sound velocities and elastic moduli for direct application to problems in geophysics. Although possibility of simultaneous high-pressure and high-temperature GUI measurements in diamond anvil cell was demonstrated before up to temperature of 250°C, in situ pressure measurements were not possible. We developed new experimental setup for simultaneous GUI and pressure determination using a ruby fluorescence gouge. A diamond anvil cell is equipped with a miniature internal resistive heater with thermocouple fixed at a very small distance from the sample chamber. DAC is mounted at the rotating stage with 5 degrees of freedom (XYZ and two tilting degrees), that can be fixed in three different positions: on top of a P-buffer rod for compressional wave velocities measurement, on top of S-buffer rod for shear wave velocities measurement and under the microscope, equipped with laser and portable high-resolution spectrometer for ruby fluorescence measurement. DAC under high temperature could be moved between these three positions, and independent pressure, temperature, S and P wave velocities measurements could be done simultaneously at each data point. In addition to single-crystal elasticity measurements, ability of GUI for elasticity measurements of liquids was demonstrated. Compressional wave velocities in liquid argon were measured at high pressures and temperatures, showing the ability of GUI for studies equation of state of a liquid.

Future heat waves and surface ozone

NASA Astrophysics Data System (ADS)

Meehl, Gerald A.; Tebaldi, Claudia; Tilmes, Simone; Lamarque, Jean-Francois; Bates, Susan; Pendergrass, Angeline; Lombardozzi, Danica

2018-06-01

A global Earth system model is used to study the relationship between heat waves and surface ozone levels over land areas around the world that could experience either large decreases or little change in future ozone precursor emissions. The model is driven by emissions of greenhouse gases and ozone precursors from a medium-high emission scenario (Representative Concentration Pathway 6.0–RCP6.0) and is compared to an experiment with anthropogenic ozone precursor emissions fixed at 2005 levels. With ongoing increases in greenhouse gases and corresponding increases in average temperature in both experiments, heat waves are projected to become more intense over most global land areas (greater maximum temperatures during heat waves). However, surface ozone concentrations on future heat wave days decrease proportionately more than on non-heat wave days in areas where ozone precursors are prescribed to decrease in RCP6.0 (e.g. most of North America and Europe), while surface ozone concentrations in heat waves increase in areas where ozone precursors either increase or have little change (e.g. central Asia, the Mideast, northern Africa). In the stabilized ozone precursor experiment, surface ozone concentrations increase on future heat wave days compared to non-heat wave days in most regions except in areas where there is ozone suppression that contributes to decreases in ozone in future heat waves. This is likely associated with effects of changes in isoprene emissions at high temperatures (e.g. west coast and southeastern North America, eastern Europe).

Wave dispersion of carbon nanotubes conveying fluid supported on linear viscoelastic two-parameter foundation including thermal and small-scale effects

NASA Astrophysics Data System (ADS)

Sina, Nima; Moosavi, Hassan; Aghaei, Hosein; Afrand, Masoud; Wongwises, Somchai

2017-01-01

In this paper, for the first time, a nonlocal Timoshenko beam model is employed for studying the wave dispersion of a fluid-conveying single-walled carbon nanotube on Viscoelastic Pasternak foundation under high and low temperature change. In addition, the phase and group velocity for the nanotube are discussed, respectively. The influences of Winkler and Pasternak modulus, homogenous temperature change, steady flow velocity and damping factor of viscoelastic foundation on wave dispersion of carbon nanotubes are investigated. It was observed that the characteristic of the wave for carbon nanotubes conveying fluid is the normal dispersion. Moreover, implying viscoelastic foundation leads to increasing the wave frequencies.

Future changes of temperature and heat waves in Ontario, Canada

NASA Astrophysics Data System (ADS)

Li, Zhong; Huang, Guohe; Huang, Wendy; Lin, Qianguo; Liao, Renfei; Fan, Yurui

2018-05-01

Apparent changes in the temperature patterns in recent years brought many challenges to the province of Ontario, Canada. As the need for adapting to climate change challenges increases, the development of reliable climate projections becomes a crucial task. In this study, a regional climate modeling system, Providing Regional Climates for Impacts Studies (PRECIS), is used to simulate the temperature patterns in Ontario. Three PRECIS runs with a resolution of 25 km × 25 km are carried out to simulate the present (1961-1990) temperature variations. There is a good match between the simulated and observed data, which validates the performance of PRECIS in reproducing temperature changes in Ontario. Future changes of daily maximum, mean, and minimum temperatures during the period 2071-2100 are then projected under the IPCC SRES A2 and B2 emission scenarios using PRECIS. Spatial variations of annual mean temperature, mean diurnal range, and temperature seasonality are generated. Furthermore, heat waves defined based on the exceedance of local climatology and their temporal and spatial characteristics are analyzed. The results indicate that the highest temperature and the most intensive heat waves are most likely to occur at the Toronto-Windsor corridor in Southern Ontario. The Northern Ontario, in spite of the relatively low projected temperature, would be under the risk of long-lasting heat waves, and thus needs effective measures to enhance its climate resilience in the future. This study can assist the decision makers in better understanding the future temperature changes in Ontario and provide decision support for mitigating heat-related loss.

Investigations of the internal wave characteristics and saturation degree in the Earth's atmosphere by using radiosonde measurements of wind and temperature and their applications to the RO wave studies

NASA Astrophysics Data System (ADS)

Kirillovich, Ivan; Gubenko, Vladimir; Pavelyev, Alexander

Internal gravity waves (IGWs) affect the structure and circulation of the Earth’s atmosphere by transporting energy and momentum upward from lower atmosphere. Observations of the temperature and wind velocity fluctuations in the middle atmosphere have shown that wave amplitudes grow with increasing altitude, however, no quickly enough in order to correspond to amplitude growth due to exponential decrease of density in the absence of energy dissipation. The theory of saturated IGWs explains such rate of the wave amplitude growth in the following way: any wave amplitude in excess of the threshold value will lead to instability and the production of turbulence that acts to prevent further growth of the wave amplitude. The mechanisms that contribute most to the dissipation and saturation of the dominant IGW motions in the atmosphere are thought to be the dynamical (shear) and convective instability. For high-frequency waves, the threshold amplitude required to achieve shear instability is virtually identical to that required for convective instability. But for low-frequency IGWs, the shear instability threshold falls well below that necessary for convective instability. The knowledge of actual and threshold wave amplitudes is important when the effect of IGWs on the background atmosphere is to be assessed. The internal wave saturation assumption plays the key role for radio occultation (RO) investigations of IGWs in planetary atmospheres [Gubenko et al., 2008, 2011, 2012], therefore a radiosonde study of wave saturation processes in the Earth’s atmosphere is actual task. The results of determination of the actual and threshold amplitudes, saturation degree and other characteristics for identified IGWs in the Earth’s atmosphere found from high-resolution radiosonde measurements SPARC (http://www.sparc.sunysb.edu/) of horizontal wind and temperature are presented. The usefulness of these observations in conjunction with RO studies of IGWs is discussed. The work was carried out under partial support of the RFBR grant 13-02-00526-a and Program 22 of the RAS Presidium. References. Gubenko V.N., Pavelyev A.G., Andreev V.E. Determination of the intrinsic frequency and other wave parameters from a single vertical temperature or density profile measurement // J. Geophys. Res. 2008. V. 113. No.D08109, doi:10.1029/2007JD008920. Gubenko V.N., Pavelyev A.G., Salimzyanov R.R., Pavelyev A.A. Reconstruction of internal gravity wave parameters from radio occultation retrievals of vertical temperature profiles in the Earth’s atmosphere // Atmos. Meas. Tech. 2011. V. 4. No.10. P. 2153-2162, doi:10.5194/amt-4-2153-2011. Gubenko V.N., Pavelyev A.G., Salimzyanov R.R., Andreev V.E. A method for determination of internal gravity wave parameters from a vertical temperature or density profile measurement in the Earth’s atmosphere // Cosmic Res. 2012. V. 50. No.1. P. 21-31, doi: 10.1134/S0010952512010029.

Resolving high-frequency internal waves generated at an isolated coral atoll using an unstructured grid ocean model

NASA Astrophysics Data System (ADS)

Rayson, Matthew D.; Ivey, Gregory N.; Jones, Nicole L.; Fringer, Oliver B.

2018-02-01

We apply the unstructured grid hydrodynamic model SUNTANS to investigate the internal wave dynamics around Scott Reef, Western Australia, an isolated coral reef atoll located on the edge of the continental shelf in water depths of 500,m and more. The atoll is subject to strong semi-diurnal tidal forcing and consists of two relatively shallow lagoons separated by a 500 m deep, 2 km wide and 15 km long channel. We focus on the dynamics in this channel as the internal tide-driven flow and resulting mixing is thought to be a key mechanism controlling heat and nutrient fluxes into the reef lagoons. We use an unstructured grid to discretise the domain and capture both the complex topography and the range of internal wave length scales in the channel flow. The model internal wave field shows super-tidal frequency lee waves generated by the combination of the steep channel topography and strong tidal flow. We evaluate the model performance using observations of velocity and temperature from two through water-column moorings in the channel separating the two reefs. Three different global ocean state estimate datasets (global HYCOM, CSIRO Bluelink, CSIRO climatology atlas) were used to provide the model initial and boundary conditions, and the model outputs from each were evaluated against the field observations. The scenario incorporating the CSIRO Bluelink data performed best in terms of through-water column Murphy skill scores of water temperature and eastward velocity variability in the channel. The model captures the observed vertical structure of the tidal (M2) and super-tidal (M4) frequency temperature and velocity oscillations. The model also predicts the direction and magnitude of the M2 internal tide energy flux. An energy analysis reveals a net convergence of the M2 energy flux and a divergence of the M4 energy flux in the channel, indicating the channel is a region of either energy transfer to higher frequencies or energy loss to dissipation. This conclusion is supported by the mooring observations that reveal high frequency lee waves breaking on the turning phase of the tide.

Analysis of pulse thermography using similarities between wave and diffusion propagation

NASA Astrophysics Data System (ADS)

Gershenson, M.

2017-05-01

Pulse thermography or thermal wave imaging are commonly used as nondestructive evaluation (NDE) method. While the technical aspect has evolve with time, theoretical interpretation is lagging. Interpretation is still using curved fitting on a log log scale. A new approach based directly on the governing differential equation is introduced. By using relationships between wave propagation and the diffusive propagation of thermal excitation, it is shown that one can transform from solutions in one type of propagation to the other. The method is based on the similarities between the Laplace transforms of the diffusion equation and the wave equation. For diffusive propagation we have the Laplace variable s to the first power, while for the wave propagation similar equations occur with s2. For discrete time the transformation between the domains is performed by multiplying the temperature data vector by a matrix. The transform is local. The performance of the techniques is tested on synthetic data. The application of common back projection techniques used in the processing of wave data is also demonstrated. The combined use of the transform and back projection makes it possible to improve both depth and lateral resolution of transient thermography.

Isentropic Analysis of Convective Motions

NASA Technical Reports Server (NTRS)

Pauluis, Olivier M.; Mrowiec, Agnieszka A.

2013-01-01

This paper analyzes the convective mass transport by sorting air parcels in terms of their equivalent potential temperature to determine an isentropic streamfunction. By averaging the vertical mass flux at a constant value of the equivalent potential temperature, one can compute an isentropic mass transport that filters out reversible oscillatory motions such as gravity waves. This novel approach emphasizes the fact that the vertical energy and entropy transports by convection are due to the combination of ascending air parcels with high energy and entropy and subsiding air parcels with lower energy and entropy. Such conditional averaging can be extended to other dynamic and thermodynamic variables such as vertical velocity, temperature, or relative humidity to obtain a comprehensive description of convective motions. It is also shown how this approach can be used to determine the mean diabatic tendencies from the three-dimensional dynamic and thermodynamic fields. A two-stream approximation that partitions the isentropic circulation into a mean updraft and a mean downdraft is also introduced. This offers a straightforward way to identify the mean properties of rising and subsiding air parcels. The results from the two-stream approximation are compared with two other definitions of the cloud mass flux. It is argued that the isentropic analysis offers a robust definition of the convective mass transport that is not tainted by the need to arbitrarily distinguish between convection and its environment, and that separates the irreversible convective overturning fromoscillations associated with gravity waves.

Measuring Temperature-Dependent Propagating Disturbances in Coronal Fan Loops Using Multiple SDO-AIA Channels and Surfing Transform Technique

NASA Technical Reports Server (NTRS)

Uritskiy, Vadim M.; Davila, Joseph M.; Viall, Nicholeen M.; Ofman, Leon

2013-01-01

A set of co-aligned high resolution images from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO) is used to investigate propagating disturbances (PDs) in warm fan loops at the periphery of a non-flaring active region NOAA AR 11082. To measure PD speeds at multiple coronal temperatures, a new data analysis methodology is proposed enabling quantitative description of sub visual coronal motions with low signal-to-noise ratios of the order of 0.1. The technique operates with a set of one-dimensional surfing signals extracted from position-timeplots of several AIA channels through a modified version of Radon transform. The signals are used to evaluate a two-dimensional power spectral density distribution in the frequency - velocity space which exhibits a resonance in the presence of quasi-periodic PDs. By applying this analysis to the same fan loop structures observed in several AIA channels, we found that the traveling velocity of PDs increases with the temperature of the coronal plasma following the square root dependence predicted for the slow mode magneto-acoustic wave which seems to be the dominating wave mode in the studied loop structures. This result extends recent observations by Kiddie et al. (2012) to a more general class of fan loop systems not associated with sunspots and demonstrating consistent slow mode activity in up to four AIA channels.

Characterization of n-Type and p-Type Long-Wave InAs/InAsSb Superlattices

NASA Astrophysics Data System (ADS)

Brown, A. E.; Baril, N.; Zuo, D.; Almeida, L. A.; Arias, J.; Bandara, S.

2017-09-01

The influence of dopant concentration on both in-plane mobility and minority carrier lifetime in long-wave infrared InAs/InAsSb superlattices (SLs) was investigated. Unintentially doped ( n-type) and various concentrations of Be-doped ( p-type) SLs were characterized using variable-field Hall and photoconductive decay techniques. Minority carrier lifetimes in p-type InAs/InAsSb SLs are observed to decrease with increasing carrier concentration, with the longest lifetime at 77 K determined to be 437 ns, corresponding to a measured carrier concentration of p 0 = 4.1 × 1015 cm-3. Variable-field Hall technique enabled the extraction of in-plane hole, electron, and surface electron transport properties as a function of temperature. In-plane hole mobility is not observed to change with doping level and increases with reducing temperature, reaching a maximum at the lowest temperature measured of 30 K. An activation energy of the Be-dopant is determined to be 3.5 meV from Arrhenius analysis of hole concentration. Minority carrier electrons populations are suppressed at the highest Be-doping levels, but mobility and concentration values are resolved in lower-doped samples. An average surface electron conductivity of 3.54 × 10-4 S at 30 K is determined from the analysis of p-type samples. Effects of passivation treatments on surface conductivity will be presented.

Mesoscale Gravity Wave Variances from AMSU-A Radiances

NASA Technical Reports Server (NTRS)

Wu, Dong L.

2004-01-01

A variance analysis technique is developed here to extract gravity wave (GW) induced temperature fluctuations from NOAA AMSU-A (Advanced Microwave Sounding Unit-A) radiance measurements. By carefully removing the instrument/measurement noise, the algorithm can produce reliable GW variances with the minimum detectable value as small as 0.1 K2. Preliminary analyses with AMSU-A data show GW variance maps in the stratosphere have very similar distributions to those found with the UARS MLS (Upper Atmosphere Research Satellite Microwave Limb Sounder). However, the AMSU-A offers better horizontal and temporal resolution for observing regional GW variability, such as activity over sub-Antarctic islands.

Metachronal wave analysis for non-Newtonian fluid under thermophoresis and Brownian motion effects

NASA Astrophysics Data System (ADS)

Shaheen, A.; Nadeem, S.

This paper analyse the mathematical model of ciliary motion in an annulus. The effect of convective heat transfer and nanoparticle are taken into account. The governing equations of Jeffrey six-constant fluid along with heat and nanoparticle are modelled and then simplified by using long wavelength and low Reynolds number assumptions. The reduced equations are solved with the help of homotopy perturbation method. The obtained expressions for the velocity, temperature and nanoparticles concentration profiles are plotted and the impact of various physical parameters are investigated for different peristaltic waves. Streamlines has also been plotted at the last part of the paper.

Prospects of Anderson's theorem for disordered cuprate superconductors

NASA Astrophysics Data System (ADS)

Ghosal, Amit; Chakraborty, Debmalya; Kaushal, Nitin

2018-05-01

We develop a simple pairing theory of superconductivity in strongly correlated d-wave superconductors for up to a moderate strength of disorder. Our description implements the key ideas of Anderson, originally proposed for disordered s-wave superconductors, but in addition takes care of the inherent strong electronic repulsion in these compounds, as well as the inhomogeneities. We first obtain the self-consistent one-particle states, that capture the effects of disorder exactly, and strong correlations using Gutzwiller approximation. These 'normal states' (at zero temperature) when coupled through BCS-type pairing attractions, produces results which are nearly identical to those from a more sophisticated Gutzwiller augmented Bogoliubov-de Gennes analysis.

Observations of electron vortex magnetic holes and related wave-particle interactions in the turbulent magnetosheath

NASA Astrophysics Data System (ADS)

Huang, S.; Sahraoui, F.; Yuan, Z.; He, J.; Zhao, J.; Du, J.; Le Contel, O.; Wang, X.; Deng, X.; Fu, H.; Zhou, M.; Shi, Q.; Breuillard, H.; Pang, Y.; Yu, X.; Wang, D.

2017-12-01

Magnetic hole is characterized by a magnetic depression, a density peak, a total electron temperature increase (with a parallel temperature decrease but a perpendicular temperature increase), and strong currents carried by the electrons. The current has a dip in the core region of the magnetic hole and a peak in the outer region of the magnetic hole. There is an enhancement in the perpendicular electron fluxes at 90° pitch angles inside the magnetic hole, implying that the electrons are trapped within it. The variations of the electron velocity components Vem and Ven suggest that an electron vortex is formed by trapping electrons inside the magnetic hole in the circular cross-section. These observations demonstrate the existence of a new type of coherent structures behaving as an electron vortex magnetic hole in turbulent space plasmas as predicted by recent kinetic simulations. We perform a statistically study using high time solution data from the MMS mission. The magnetic holes with short duration (i.e., < 0.5 s) have their cross section smaller than the ion gyro-radius. Superposed epoch analysis of all events reveals that an increase in the electron density and total temperature, significantly increase (resp. decrease) the electron perpendicular (resp. parallel) temperature, and an electron vortex inside the holes. Electron fluxes at 90° pitch angles with selective energies increase in the KSMHs, are trapped inside KSMHs and form the electron vortex due to their collective motion. All these features are consistent with the electron vortex magnetic holes obtained in 2D and 3D particle-in-cell simulations, indicating that the observed the magnetic holes seem to be best explained as electron vortex magnetic holes. It is furthermore shown that the magnetic holes are likely to heat and accelerate the electrons. We also investigate the coupling between whistler waves and electron vortex magnetic holes. These whistler waves can be locally generated inside electron vortex magnetic holes by electron temperature anisotropic instability.

Polarization and wavelength diversities of Gulf Stream fronts imaged by AIRSAR

NASA Technical Reports Server (NTRS)

Lee, J. S.; Jansen, R. W.; Marmorino, G. O.; Chubb, S. R.

1995-01-01

During the 1990 Gulf Stream Experiment, NASA/JPL AIRSAR imaged the north edge of the Gulf Stream near the coast of Virginia. Simultaneous in-situ measurements of currents, temperatures, salinities, etc. were made for several crossings of the north edge by the R/V Cape Henlopen. Measurements identified two fronts with shearing and converging flows. The polarimetric SAR images from the fronts showed two bright linear features. One of them corresponds to the temperature front, which separated the warm Gulf Stream water to the south from a cool, freshwater filament to the north. The other line, located about 8 km north of the temperature front, is believed to correspond to the velocity front between the filament and the slope water. At these fronts, wave-current interactions produced narrow bands of steep and breaking waves manifesting higher radar returns in polarimetric SAR images. In general, our AIRSAR imagery shows that the signal-to-clutter ratio of radar cross sections for the temperature front is higher than that of the velocity front. In this paper, we study the polarization and wavelength diversities of radar response of these two fronts using the P-, L-, and C-Band Polarimetric SAR data. The north-south flight path of the AIRSAR crossed the temperature front several times and provided valuable data for analysis. Three individual passes are investigated. We found that for the temperature front, the cross-pol (HV) responses are much higher than co-pol responses (VV and HH), and that P-Band HV has the highest signal to clutter ratio. For the velocity front, the ratio is the strongest in P-Band VV, and it is indistinguishable for all polarizations in C-Band. The radar cross sections for all three polarization (HH, HV, and VV) and for all three bands are modelled using an ocean wave model and a composite Bragg scattering model. In our initial investigations, the theoretical model agrees qualitatively with the AIRSAR observations.

Impact of simulated heat waves on soybean physiology and yield

USDA-ARS?s Scientific Manuscript database

With increases in mean global temperatures and associated climate change, extreme temperature events are predicted to increase in both intensity and frequency. Despite the clearly documented negative public health impacts of heat waves, the impact on physiology and yields of key agricultural species...

Room temperature continuous wave, monolithic tunable THz sources based on highly efficient mid-infrared quantum cascade lasers

PubMed Central

Lu, Quanyong; Wu, Donghai; Sengupta, Saumya; Slivken, Steven; Razeghi, Manijeh

2016-01-01

A compact, high power, room temperature continuous wave terahertz source emitting in a wide frequency range (ν ~ 1–5 THz) is of great importance to terahertz system development for applications in spectroscopy, communication, sensing, and imaging. Here, we present a strong-coupled strain-balanced quantum cascade laser design for efficient THz generation based on intracavity difference frequency generation. Room temperature continuous wave emission at 3.41 THz with a side-mode suppression ratio of 30 dB and output power up to 14 μW is achieved with a wall-plug efficiency about one order of magnitude higher than previous demonstrations. With this highly efficient design, continuous wave, single mode THz emissions with a wide frequency tuning range of 2.06–4.35 THz and an output power up to 4.2 μW are demonstrated at room temperature from two monolithic three-section sampled grating distributed feedback-distributed Bragg reflector lasers. PMID:27009375

Thermal Hall conductivity in the spin-triplet superconductor with broken time-reversal symmetry

NASA Astrophysics Data System (ADS)

Imai, Yoshiki; Wakabayashi, Katsunori; Sigrist, Manfred

2017-01-01

Motivated by the spin-triplet superconductor Sr2RuO4 , the thermal Hall conductivity is investigated for several pairing symmetries with broken time-reversal symmetry. In the chiral p -wave phase with a fully opened quasiparticle excitation gap, the temperature dependence of the thermal Hall conductivity has a temperature linear term associated with the topological property directly and an exponential term, which shows a drastic change around the Lifshitz transition. Examining f -wave states as alternative candidates with d =Δ0z ̂(kx2-ky2) (kx±i ky) and Δ0z ̂kxky(kx±i ky) with gapless quasiparticle excitations, we study the temperature dependence of the thermal Hall conductivity, where for the former state the thermal Hall conductivity has a quadratic dependence on temperature, originating from the linear dispersions, in addition to linear and exponential behavior. The obtained result may enable us to distinguish between the chiral p -wave and f -wave states in Sr2RuO4 .

The effects of shock wave compaction on the transition temperatures of A15 structure superconductors

NASA Technical Reports Server (NTRS)

Otto, G. H.

1974-01-01

Several superconductors with the A15 structure exhibit a positive pressure coefficient, indicating that their transition temperatures increase with applied pressure. Powders of the composition Nb3Al, Nb3Ge, Nb3(Al0.75Ge0.25), and V3Si were compacted by explosive shock waves. The superconducting properties of these materials were measured before and after compaction and it was found that regardless of the sign of the pressure coefficient, the transition temperature is always lowered. The decrease in transition temperature is associated with a decrease in the particle diameter. The shock wave passage through a 3Nb:1Ge powder mixture leads to the formation of at least one compound (probably Nb5Ge3). However, the formation of the A15 compound Nb3Ge is not observed. Elemental niobium powder can be compacted by converging shock waves close to the expected value of the bulk density. Under special circumstances a partial remelting in the center of the sample is observed.

Room temperature continuous wave, monolithic tunable THz sources based on highly efficient mid-infrared quantum cascade lasers.

PubMed

Lu, Quanyong; Wu, Donghai; Sengupta, Saumya; Slivken, Steven; Razeghi, Manijeh

2016-03-24

A compact, high power, room temperature continuous wave terahertz source emitting in a wide frequency range (ν~1-5 THz) is of great importance to terahertz system development for applications in spectroscopy, communication, sensing, and imaging. Here, we present a strong-coupled strain-balanced quantum cascade laser design for efficient THz generation based on intracavity difference frequency generation. Room temperature continuous wave emission at 3.41 THz with a side-mode suppression ratio of 30 dB and output power up to 14 μW is achieved with a wall-plug efficiency about one order of magnitude higher than previous demonstrations. With this highly efficient design, continuous wave, single mode THz emissions with a wide frequency tuning range of 2.06-4.35 THz and an output power up to 4.2 μW are demonstrated at room temperature from two monolithic three-section sampled grating distributed feedback-distributed Bragg reflector lasers.

A new approach to measure the temperature in rapid thermal processing

NASA Astrophysics Data System (ADS)

Yan, Jiang

This dissertation has presented the research work about a new method to measure the temperatures for the silicon wafer. The new technology is mainly for the rapid thermal processing (RTP) system. RTP is a promising technology in semiconductor manufacturing especially for the devices with minimum feature size less than 0.5 μm. The technique to measure the temperatures of the silicon wafer accurately is the key factor to apply the RTP technology to more critical processes in the manufacturing. Two methods which are mostly used nowadays, thermocouples and pyrometer, all have the limitation to be applied in the RTP. This is the motivation to study the new method using acoustic waves for the temperature measurement. The test system was designed and built up for the study of the acoustic method. The whole system mainly includes the transducer unit, circuit hardware, control software, the computer, and the chamber. The acoustic wave was generated by the PZT-5H transducer. The wave travels through the quartz rod into the silicon wafer. After traveling a certain distances in the wafer, the acoustic waves could be received by other transducers. By measuring the travel time and with the travel distance, the velocity of the acoustic wave traveling in the silicon wafer can be calculated. Because there is a relationship between the velocity and the temperature: the velocities of the acoustic waves traveling in the silicon wafer decrease as the temperatures of the wafer increase, the temperature of the wafer can be finally obtained. The thermocouples were used to check the measurement accuracy of the acoustic method. The temperature mapping across the 8″ silicon wafer was obtained with four transducer sensor unit. The temperatures of the wafer were measured using acoustic method at both static and dynamic status. The main purpose of the tests is to know the measurement accuracy for the new method. The goal of the research work regarding to the accuracy is <=+/-3°C. The measurement was also done under the different wafer conditions in order to clarify that the acoustic method is independent of the wafer conditions.

Coastal Land Air Sea Interaction: "the" beach towers

NASA Astrophysics Data System (ADS)

MacMahan, J. H.; Koscinski, J. S.; Ortiz-Suslow, D. G.; Haus, B. K.; Thornton, E. B.

2016-12-01

As part of the Coastal Land Air Sea Interaction (CLASI) experiment, an alongshore array of 6-m high towers instrumented with ultrasonic 3D anemometers and temperature-relative humidity sensors were deployed at five sandy beaches near the high-tide line in Monterey Bay, CA, in May-June 2016. A cross-shore array of towers was also deployed from within the active surfzone to the toe of the dune at one beach. In addition, waves and ocean temperature were obtained along the 10m isobath for each beach. The dissipative surfzone was O(80m) wide. The wave energy varies among the beaches owing to sheltering and refraction by the Monterey Canyon and headlands. The tides are semi-diurnal mixed, meso-tidal with a maximum tidal range of 2m. This results in a variable beach width from the tower to the tidal line. Footprint analysis for estimating the source region for the turbulent momentum fluxes, suggests that the observations represent three scenarios described as primarily ocean, mixed beach and ocean, and primarily beach. The direct-estimate of the atmospheric stability by the sonic anemometer suggest that all of the beaches are mostly unstable except for a few occurrences in the evening during low wind conditions. The onshore neutral drag coefficient (Cd) estimated at 10m heights is 3-5 times larger than open ocean estimates. Minimal variability was found in Cd based on the footprint analysis. Beach-specific spatial variability in Cd was found related to atmospheric stability and wave energy.

The short-term effect of heat waves on mortality and its modifiers in China: an analysis from 66 communities.

PubMed

Ma, Wenjun; Zeng, Weilin; Zhou, Maigeng; Wang, Lijun; Rutherford, Shannon; Lin, Hualiang; Liu, Tao; Zhang, Yonghui; Xiao, Jianpeng; Zhang, Yewu; Wang, Xiaofeng; Gu, Xin; Chu, Cordia

2015-02-01

Many studies have reported increased mortality risk associated with heat waves. However, few have assessed the health impacts at a nation scale in a developing country. This study examines the mortality effects of heat waves in China and explores whether the effects are modified by individual-level and community-level characteristics. Daily mortality and meteorological variables from 66 Chinese communities were collected for the period 2006-2011. Heat waves were defined as ≥2 consecutive days with mean temperature ≥95th percentile of the year-round community-specific distribution. The community-specific mortality effects of heat waves were first estimated using a Distributed Lag Non-linear Model (DLNM), adjusting for potential confounders. To investigate effect modification by individual characteristics (age, gender, cause of death, education level or place of death), separate DLNM models were further fitted. Potential effect modification by community characteristics was examined using a meta-regression analysis. A total of 5.0% (95% confidence intervals (CI): 2.9%-7.2%) excess deaths were associated with heat waves in 66 Chinese communities, with the highest excess deaths in north China (6.0%, 95% CI: 1%-11.3%), followed by east China (5.2%, 95% CI: 0.4%-10.2%) and south China (4.5%, 95% CI: 1.4%-7.6%). Our results indicate that individual characteristics significantly modified heat waves effects in China, with greater effects on cardiovascular mortality, cerebrovascular mortality, respiratory mortality, the elderly, females, the population dying outside of a hospital and those with a higher education attainment. Heat wave mortality effects were also more pronounced for those living in urban cities or densely populated communities. Heat waves significantly increased mortality risk in China with apparent spatial heterogeneity, which was modified by some individual-level and community-level factors. Our findings suggest adaptation plans that target vulnerable populations in susceptible communities during heat wave events should be developed to reduce health risks. Copyright © 2014 Elsevier Ltd. All rights reserved.

Observable induced gravitational waves from an early matter phase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alabidi, Laila; Sasaki, Misao; Kohri, Kazunori

2013-05-01

Assuming that inflation is succeeded by a phase of matter domination, which corresponds to a low temperature of reheating T{sub r} < 10{sup 9}GeV, we evaluate the spectra of gravitational waves induced in the post-inflationary universe. We work with models of hilltop-inflation with an enhanced primordial scalar spectrum on small scales, which can potentially lead to the formation of primordial black holes. We find that a lower reheat temperature leads to the production of gravitational waves with energy densities within the ranges of both space and earth based gravitational wave detectors.

Effect of electron beam on the properties of electron-acoustic rogue waves

NASA Astrophysics Data System (ADS)

El-Shewy, E. K.; Elwakil, S. A.; El-Hanbaly, A. M.; Kassem, A. I.

2015-04-01

The properties of nonlinear electron-acoustic rogue waves have been investigated in an unmagnetized collisionless four-component plasma system consisting of a cold electron fluid, Maxwellian hot electrons, an electron beam and stationary ions. It is found that the basic set of fluid equations is reduced to a nonlinear Schrodinger equation. The dependence of rogue wave profiles and the associated electric field on the carrier wave number, normalized density of hot electron and electron beam, relative cold electron temperature and relative beam temperature are discussed. The results of the present investigation may be applicable in auroral zone plasma.

HOT PLASMA FROM SOLAR ACTIVE-REGION CORES: CONSTRAINTS FROM THE HINODE X-RAY TELESCOPE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schmelz, J. T.; Christian, G. M.; Matheny, P. O., E-mail: jschmelz@usra.edu

2016-12-20

Mechanisms invoked to heat the solar corona to millions of degrees kelvin involve either magnetic waves or magnetic reconnections. Turbulence in the convection zone produces MHD waves, which travel upward and dissipate. Photospheric motions continuously build up magnetic energy, which is released through magnetic reconnection. In this paper, we concentrate on hot non-flaring plasma with temperatures of 5 MK <  T  < 10 MK because it is one of the few observables for which wave and reconnection models make different predictions. Wave models predict no (or little) hot plasma, whereas reconnection models predict it, although in amounts that are challenging to detectmore » with current instrumentation. We used data from the X-ray Telescope (XRT) and the Atmospheric Imaging Assembly (AIA). We requested a special XRT observing sequence, which cycled through the thickest XRT filter several times per hour so we could average these images and improve the signal-to-noise. We did differential emission measure (DEM) analysis using the time-averaged thick-filter data as well as all available channels from both the XRT and AIA for regions observed on 2014 December 11. Whereas our earlier work was only able to determine that plasma with a temperature greater than 5 MK was present , we are now able to find a well-constrained DEM distribution. We have therefore added a strong observational constraint that must be explained by any viable coronal heating model. Comparing state-of-the-art wave and reconnection model predictions, we can conclude that reconnection is heating the hot plasma in these active regions.« less

Numerical study of heterogeneous mean temperature and shock wave in a resonator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yano, Takeru

2015-10-28

When a frequency of gas oscillation in an acoustic resonator is sufficiently close to one of resonant frequencies of the resonator, the amplitude of gas oscillation becomes large and hence the nonlinear effect manifests itself. Then, if the dissipation effects due to viscosity and thermal conductivity of the gas are sufficiently small, the gas oscillation may evolve into the acoustic shock wave, in the so-called consonant resonators. At the shock front, the kinetic energy of gas oscillation is converted into heat by the dissipation process inside the shock layer, and therefore the temperature of the gas in the resonator rises.more » Since the acoustic shock wave travels in the resonator repeatedly over and over again, the temperature rise becomes noticeable in due course of time even if the shock wave is weak. We numerically study the gas oscillation with shock wave in a resonator of square cross section by solving the initial and boundary value problem of the system of three-dimensional Navier-Stokes equations with a finite difference method. In this case, the heat conduction across the boundary layer on the wall of resonator causes a spatially heterogeneous distribution of mean (time-averaged) gas temperature.« less

Shock and Rarefaction Waves in a Heterogeneous Mantle

NASA Astrophysics Data System (ADS)

Jordan, J.; Hesse, M. A.

2012-12-01

We explore the effect of heterogeneities on partial melting and melt migration during active upwelling in the Earth's mantle. We have constructed simple, explicit nonlinear models in one dimension to examine heterogeneity and its dynamic affects on porosity, temperature and the magnesium number in a partially molten, porous medium comprised of olivine. The composition of the melt and solid are defined by a closed, binary phase diagram for a simplified, two-component olivine system. The two-component solid solution is represented by a phase loop where concentrations 0 and 1 to correspond to fayalite and forsterite, respectively. For analysis, we examine an advective system with a Riemann initial condition. Chromatographic tools and theory have primarily been used to track large, rare earth elements as tracers. In our case, we employ these theoretical tools to highlight the importance of the magnesium number, enthalpy and overall heterogeneity in the dynamics of melt migration. We calculate the eigenvectors and eigenvalues in the concentration-enthalpy space in order to glean the characteristics of the waves emerging the Riemann step. Analysis on Riemann problems of this nature shows us that the composition-enthalpy waves can be represented by self-similar solutions. The eigenvalues of the composition-enthalpy system represent the characteristic wave propagation speeds of the compositions and enthalpy through the domain. Furthermore, the corresponding eigenvectors are the directions of variation, or ``pathways," in concentration-enthalpy space that the characteristic waves follow. In the two-component system, the Riemann problem yields two waves connected by an intermediate concentration-enthalpy state determined by the intersections of the integral curves of the eigenvectors emanating from both the initial and boundary states. The first wave, ``slow path," and second wave, ``fast path," follow the aformentioned pathways set by the eigenvectors. The slow path wave has a zero eigenvalue, corresponding to a wave speed of zero, which preserves a residual imprint of the initial condition. Freezing fronts textemdash those that result in a negative change in porositytextemdash feature fast path waves that travel as shocks, whereas the fast path waves of melting fronts travel as spreading, rarefaction waves.

Spin waves in full-polarized state of Dzyaloshinskii-Moriya helimagnets: Small-angle neutron scattering study

NASA Astrophysics Data System (ADS)

Grigoriev, S. V.; Sukhanov, A. S.; Altynbaev, E. V.; Siegfried, S.-A.; Heinemann, A.; Kizhe, P.; Maleyev, S. V.

2015-12-01

We develop the technique to study the spin-wave dynamics of the full-polarized state of the Dzyaloshinskii-Moriya helimagnets by polarized small-angle neutron scattering. We have experimentally proven that the spin-waves dispersion in this state has the anisotropic form. We show that the neutron scattering image displays a circle with a certain radius which is centered at the momentum transfer corresponding to the helix wave vector in helimagnetic phase ks, which is oriented along the applied magnetic field H . The radius of this circle is directly related to the spin-wave stiffness of this system. This scattering depends on the neutron polarization showing the one-handed nature of the spin waves in Dzyaloshinskii-Moriya helimagnets in the full-polarized phase. We show that the spin-wave stiffness A for MnSi helimagnet decreased twice as the temperature increases from zero to the critical temperature Tc.

Evaluation of concrete cover by surface wave technique: Identification procedure

NASA Astrophysics Data System (ADS)

Piwakowski, Bogdan; Kaczmarek, Mariusz; Safinowski, Paweł

2012-05-01

Concrete cover degradation is induced by aggressive agents in ambiance, such as moisture, chemicals or temperature variations. Due to degradation usually a thin (a few millimeters thick) surface layer has porosity slightly higher than the deeper sound material. The non destructive evaluation of concrete cover is vital to monitor the integrity of concrete structures and prevent their irreversible damage. In this paper the methodology applied by the classical technique used for ground structure recovery called Multichanel Analysis of Surface Waves is discussed as the NDT tool in civil engineering domain to characterize the concrete cover. In order to obtain the velocity as a function of sample depth the dispersion of surface waves is used as an input for solving inverse problem. The paper describes the inversion procedure and provides the practical example of use of developed system.

Long-term survey of lion-roar emissions inside the terrestrial magnetosheath obtained from the STAFF-SA measurements onboard the Cluster spacecraft

NASA Astrophysics Data System (ADS)

Pisa, D.; Krupar, V.; Kruparova, O.; Santolik, O.

2017-12-01

Intense whistler-mode emissions known as 'lion-roars' are often observed inside the terrestrial magnetosheath, where the solar wind plasma flow slows down, and the local magnetic field increases ahead of a planetary magnetosphere. Plasma conditions in this transient region lead to the electron temperature anisotropy, which can result in the whistler-mode waves. The lion-roars are narrow-band emissions with typical frequencies between 0.1-0.5 Fce, where Fce is the electron cyclotron frequency. We present results of a long-term survey obtained by the Spatio Temporal Analysis Field Fluctuations - Spectral Analyzer (STAFF-SA) instruments on board the four Cluster spacecraft between 2001 and 2010. We have visually identified the time-frequency intervals with the intense lion-roar signature. Using the Singular Value Decomposition (SVD) method, we analyzed the wave propagation properties. We show the spatial, frequency and wave power distributions. Finally, the wave properties as a function of upstream solar wind conditions are discussed.

Analysis of unsteady wave processes in a rotating channel

NASA Technical Reports Server (NTRS)

Larosiliere, L. M.; Mawid, M.

1993-01-01

The impact of passage rotation on the gas dynamic wave processes is analyzed through a numerical simulation of ideal shock-tube flow in a closed rotating-channel. Initial conditions are prescribed by assuming homentropic solid-body rotation. Relevant parameters of the problem such as wheel Mach number, hub-to-tip radius ratio, length-to-tip radius ratio, diaphragm temperature ratio, and diaphragm pressure ratio are varied. The results suggest possible criteria for assessing the consequences of passage rotation on the wave processes, and they may therefore be applicable to pressure-exchange wave rotors. It is shown that for a fixed geometry and initial conditions, the contact interface acquires a distorted three-dimensional time-dependent orientation at non-zero wheel Mach numbers. At a fixed wheel Mach number, the level of distortion depends primarily on the density ratio across the interface as well as the hub-to-tip radius ratio. Rarefaction fronts, shocks, and contact interfaces are observed to propagate faster with increasing wheel Mach number.

Two-dimensional modulated ion-acoustic excitations in electronegative plasmas

NASA Astrophysics Data System (ADS)

Panguetna, Chérif S.; Tabi, Conrad B.; Kofané, Timoléon C.

2017-09-01

Two-dimensional modulated ion-acoustic waves are investigated in an electronegative plasma. Through the reductive perturbation expansion, the governing hydrodynamic equations are reduced to a Davey-Stewartson system with two-space variables. The latter is used to study the modulational instability of ion-acoustic waves along with the effect of plasma parameters, namely, the negative ion concentration ratio (α) and the electron-to-negative ion temperature ratio (σn). A parametric analysis of modulational instability is carried out, where regions of plasma parameters responsible for the emergence of modulated ion-acoustic waves are discussed, with emphasis on the behavior of the instability growth rate. Numerically, using perturbed plane waves as initial conditions, parameters from the instability regions give rise to series of dromion solitons under the activation of modulational instability. The sensitivity of the numerical solutions to plasma parameters is discussed. Some exact solutions in the form one- and two-dromion solutions are derived and their response to the effect of varying α and σn is discussed as well.

Linear analysis of ion cyclotron interaction in a multicomponent plasma

NASA Technical Reports Server (NTRS)

Gendrin, R.; Ashour-Abdalla, M.; Omura, Y.; Quest, K.

1984-01-01

The mechanism by which hot anisotropic protons generate electromagnetic ion cyclotron waves in a plasma containing cold H(+) and He(+) ions is quantitatively studied. Linear growth rates (both temporal and spatial) are computed for different plasma parameters: concentration, temperature,and anisotropy of cold He(+) ions and of hot protons. It is shown that: (1) for parameters typical of the geostationary altitude the maximum growth rates are not drastically changed when a small proportion (about 1 to 20 percent) of cold He(+) ions is present; (2) because of the important cyclotron absorption by thermal He(+) ions in the vicinity of the He(+) gyrofrequency, waves which could resonate with the bulk of the He(+) distribution cannot be generated. Therefore quasi-linear effects, in a homogeneous medium at least, cannot be responsible for the heating of He(+) ions which is often observed in conjunction with ion cyclotron waves. The variation of growth rate versus wave number is also studied for its importance in selecting suitable parameters in numerical simulation experiments.

Seasonal gravity wave drags on the upper stratosphere due to the northwestern pacific typhoons

NASA Astrophysics Data System (ADS)

Chen, Zeyu; Lu, Daren

In a recent study of the first author and his co-authors (Zeyu Chen, Peter Preusse, Michael Jarisch, Manfred Ern, and Dirk Offermann, 2003), it has been revealed that a northwestern Pacific typhoon can generate stratospheric gravity waves with the horizontal scales ranging from 500 km ˜ 1000 km, and carrying a magnitude of ˜ 0.001 Pascal of momentum flux into the upper stratosphere Statistics indicates that the annual mean number of typhoon in the northwestern Pacific is about 32, most of them happen in summer. In this presentation, we show that a parameterization scheme is developed to derive the magnitude of the momentum flux of the waves from operational satellite observations that can scale the intensity of a typhoon (e.g. the brightness temperature observations from the GMS-5 satellite), and operational meteorological data analysis. The seasonal effect of the Gravity Wave Drags due to the typhoons in the area is derived.

Analysis of unsteady wave processes in a rotating channel

NASA Astrophysics Data System (ADS)

Larosiliere, Louis M.; Mawid, M.

1993-06-01

The impact of passage rotation on the gas dynamic wave processes is analyzed through a numerical simulation of ideal shock-tube flow in a closed rotating-channel. Initial conditions are prescribed by assuming homentropic solid-body rotation. Relevant parameters of the problem such as wheel Mach number, hub-to-tip radius ratio, length-to-tip radius ratio, diaphragm temperature ratio, and diaphragm pressure ratio are varied. The results suggest possible criteria for assessing the consequences of passage rotation on the wave processes, and they may therefore be applicable to pressure-exchange wave rotors. It is shown that for a fixed geometry and initial conditions, the contact interface acquires a distorted three-dimensional time-dependent orientation at non-zero wheel Mach numbers. At a fixed wheel Mach number, the level of distortion depends primarily on the density ratio across the interface as well as the hub-to-tip radius ratio. Rarefaction fronts, shocks, and contact interfaces are observed to propagate faster with increasing wheel Mach number.