Temperature and Pressure Dependence of Signal Amplitudes for Electrostriction Laser-Induced Thermal Acoustics

Science.gov (United States)

Herring, Gregory C.

2015-01-01

The relative signal strength of electrostriction-only (no thermal grating) laser-induced thermal acoustics (LITA) in gas-phase air is reported as a function of temperature T and pressure P. Measurements were made in the free stream of a variable Mach number supersonic wind tunnel, where T and P are varied simultaneously as Mach number is varied. Using optical heterodyning, the measured signal amplitude (related to the optical reflectivity of the acoustic grating) was averaged for each of 11 flow conditions and compared to the expected theoretical dependence of a pure-electrostriction LITA process, where the signal is proportional to the square root of [P*P /( T*T*T)].

Thermal IR satellite data application for earthquake research in Pakistan

Science.gov (United States)

Barkat, Adnan; Ali, Aamir; Rehman, Khaista; Awais, Muhammad; Riaz, Muhammad Shahid; Iqbal, Talat

2018-05-01

The scientific progress in space research indicates earthquake-related processes of surface temperature growth, gas/aerosol exhalation and electromagnetic disturbances in the ionosphere prior to seismic activity. Among them surface temperature growth calculated using the satellite thermal infrared images carries valuable earthquake precursory information for near/distant earthquakes. Previous studies have concluded that such information can appear few days before the occurrence of an earthquake. The objective of this study is to use MODIS thermal imagery data for precursory analysis of Kashmir (Oct 8, 2005; Mw 7.6; 26 km), Ziarat (Oct 28, 2008; Mw 6.4; 13 km) and Dalbandin (Jan 18, 2011; Mw 7.2; 69 km) earthquakes. Our results suggest that there exists an evident correlation of Land Surface Temperature (thermal; LST) anomalies with seismic activity. In particular, a rise of 3-10 °C in LST is observed 6, 4 and 14 days prior to Kashmir, Ziarat and Dalbandin earthquakes. In order to further elaborate our findings, we have presented a comparative and percentile analysis of daily and five years averaged LST for a selected time window with respect to the month of earthquake occurrence. Our comparative analyses of daily and five years averaged LST show a significant change of 6.5-7.9 °C for Kashmir, 8.0-8.1 °C for Ziarat and 2.7-5.4 °C for Dalbandin earthquakes. This significant change has high percentile values for the selected events i.e. 70-100% for Kashmir, 87-100% for Ziarat and 84-100% for Dalbandin earthquakes. We expect that such consistent results may help in devising an optimal earthquake forecasting strategy and to mitigate the effect of associated seismic hazards.

PRECURSORY SLOPE DEFORMATION AROUND LANDSLIDE AREA DETECTED BY INSAR THROUGHOUT JAPAN

Directory of Open Access Journals (Sweden)

T. Nakano

2016-06-01

Full Text Available Interferometric Synthetic Aperture Radar (InSAR technique is able to detect a slope deformation around landslide (e.g., Singhroy et al., 2004; Une et al., 2008; Riedel and Walther, 2008; Sato et al., 2014. Geospatial Information Authority (GSI of Japan has been performing the InSAR analysis regularly by using ALOS/PALSAR data and ALOS-2/PALSAR-2 data throughout Japan. There are a lot of small phase change sites except for crustal deformation with earthquake or volcano activity in the InSAR imagery. Most of the phase change sites are located in landslide area. We conducted field survey at the 10 sites of those phase change sites. As a result, we identified deformation of artificial structures or linear depressions caused by mass movement at the 9 sites. This result indicates that InSAR technique can detect on the continual deformation of landslide block for several years. GSI of Japan will continue to perform the InSAR analysis throughout Japan. Therefore, we will be able to observe and monitor precursory slope deformation around landslide areas throughout Japan.

On precursory ULF/ELF electromagnetic signatures for the Kobe earthquake on April 12, 2013

Science.gov (United States)

Schekotov, A.; Izutsu, J.; Hayakawa, M.

2015-12-01

After the 2011 Tohoku earthquake (EQ), there have been numerous aftershocks in the eastern and Pacific Ocean of Japan, but EQs are still rare in the western part of Japan. In this situation a relatively large (magnitude (M) ∼ 6) EQ happened on April 12 (UT), 2013 at a place close to the 1995 Kobe EQ (M ∼ 7), so we have tried to find whether there existed any electromagnetic precursors to this EQ. Two precursory signatures are detected: one is the depression of ULF (ultra-low-frequency, 0.01-0.02 Hz) geomagnetic variations on April 9, and the second is wideband ELF (extremely low frequency) electromagnetic radiation on April 11. These results for the 2013 Kobe EQ are compared with the corresponding results for the former 1995 Kobe EQ.

Radon anomalies precursory to the 2003 Mw = 6.8 Chengkung and 2006 Mw = 6.1 Taitung earthquakes in Taiwan

International Nuclear Information System (INIS)

Kuo, T.; Lin, C.; Fan, K.; Chang, G.; Lewis, C.; Han, Y.; Wu, Y.; Chen, W.; Tsai, C.

2009-01-01

Contrary to the normally observed increase in groundwater radon that occurs prior to earthquakes, we have measured anomalous decreases in radon concentration prior to the 2003 M W = 6.8 Chengkung and 2006 M W = 6.1 Taitung earthquakes that occurred within a 55 km radius from the Antung D1 monitoring well in eastern Taiwan. The v-shaped pattern of radon anomalies recognized at Antung is valuable for detecting the aseismic strain precursory to potentially disastrous earthquakes in a fractured aquifer surrounded by ductile aquitard in seismotectonic environments in this area.

Modelling the thermal bleaching of OSL signal in the case of a competition between recombination centres

International Nuclear Information System (INIS)

Chruscinska, A.

2009-01-01

The thermal bleaching of the optically stimulated luminescence (OSL) has been investigated by computer simulations for a model including three traps and two luminescence centres. The deepest trap is active only during the OSL process. Two other traps are active only during the thermal bleaching. The thermal bleaching effects on the OSL intensity as well as on the OSL curve shape are presented for the wide range of trap and luminescence centre parameters and for the different settings of optical detection window. The conventional OSL curve analysis consisting in decomposition of the OSL curve into first order components is applied to the simulation results and the optical cross section spectra obtained as a result of this analysis are compared with the model assumptions. The simulations show that OSL signal can decrease to undetectable level even when the traps related to this signal are not emptied during thermal bleaching. The residual level of the OSL signal after bleaching process, however, depends strongly on centre parameters and concentrations. The modifications of optical detection spectral window lead to significant changes of bleaching effects. The thermal bleaching influences also the optical cross section spectra obtained as a result of the OSL curve decomposition.

Precursory tremor of the Askja Caldera landslide, July 2014 - seismic signal analysis and numerical modelling

Science.gov (United States)

Lipovsky, B. P.; Schöpa, A.; Chao, W. A.; Hovius, N.; White, R. S.; Green, R. G.

2017-12-01

Seismic records can contain valuable information about triggers and precursors of slope failures that might become useful for early-warning purposes. We investigated the seismic data of 52 stations from the University of Cambridge, UK, with respect to the tremor signals preceding a 20-80x106 m3 landslide at the Askja caldera in the Icelandic highlands on 21 July 2014. The landslide created a tsunami in the caldera lake, which inundated the shore up to 60 m high reaching famous tourist spots. This shows the high hazard potential of the site that motivated this study. About 30 min before the landslide, the seismic ground velocities >1 Hz of stations up to 30 km away from the landslide source area started to increase and the tremor signal reached up to three times the background noise level about 7 min before the landslide. In the spectral domain, the tremor is visible as a continuous, harmonic signal with a fundamental frequency of 2.5 Hz and overtones at 5 and 7.5 Hz. About 10 min before the landslide, the activated frequency bands changed their spectral content and up and down gliding is observed contemporaneously. The tremor signal ceases about 5 min before the high-energy failure of the landslide. We interpret the harmonic tremor before the landslide as stick-slip motion on fault patches at the boundaries of the landslide mass. Individual stick-slip events cannot be distinguished in the seismic data and thus have already merged into continuous tremor as they occur very close in time. As up and down gliding of the frequency bands occurs at the same time we favour an explanation where several fault patches are active simultaneously. One patch might accelerate and create up gliding signals and another patch might decelerate and create down gliding. We matched synthetic seismograms produced by numerical simulations of stick-slip movement and the seismic observations. The results show that a patch with a radius of 45 m and a realistic landslide thickness of 30 m can

Volcano Monitoring using Multiple Remote Data Sources

Science.gov (United States)

Reath, K. A.; Pritchard, M. E.

2016-12-01

Satellite-based remote sensing instruments can be used to determine quantitative values related to precursory activity that can act as a warning sign of an upcoming eruption. These warning signs are measured through examining anomalous activity in: (1) thermal flux, (2) gas/aerosol emission rates, (3) ground deformation, and (4) ground-based seismic readings. Patterns in each of these data sources are then analyzed to create classifications of different phases of precursory activity. These different phases of activity act as guidelines to monitor the progression of precursory activity leading to an eruption. Current monitoring methods rely on using high temporal resolution satellite imagery from instruments like the Advanced Very High Resolution Radiometer (AVHRR) and the Moderate Resolution Imaging Spectrometer (MODIS) sensors, for variations in thermal and aerosol emissions, and the Ozone Monitoring Instruments (OMI) and Ozone Mapping Profiler Suite (OMPS) instruments, for variations in gas emissions, to provide a valuable resource for near real-time monitoring of volcanic activity. However, the low spatial resolution of these data only enable events that produce a high thermal output or a large amount of gas/aerosol emissions to be detected. High spatial resolution instruments, like the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) sensor, have a small enough pixel size (90m2) that the subtle variations in both thermal flux and gas/aerosol emission rates in the pre-eruptive period can be detected. Including these data with the already established high temporal resolution data helps to identify and classify precursory activity patterns months before an eruption (Reath et al, 2016). By correlating these data with ground surface deformation data, determined from the Interferometric Synthetic Aperture Radar (InSAR) sensor, and seismic data, collected by the Incorporated Research Institution for Seismology (IRIS) data archive, subtle

Precursory diffuse CO2 and H2S emission signatures of the 2011-2012 El Hierro submarine eruption, Canary Islands

Science.gov (United States)

Pérez, Nemesio M.; Padilla, Germán D.; Padrón, Eleazar; Hernández, Pedro A.; Melián, Gladys V.; Barrancos, José; Dionis, Samara; Nolasco, Dácil; Rodríguez, Fátima; Calvo, David; Hernández, Íñigo

2012-08-01

On October 12, 2011, a submarine eruption began 2 km off the coast of La Restinga, south of El Hierro Island. CO2 and H2S soil efflux were continuously measured during the period of volcanic unrest by using the accumulation chamber method at two different geochemical stations, HIE01 and HIE07. Recorded CO2 and H2S effluxes showed precursory signals that preceded the submarine eruption. Beginning in late August, the CO2 efflux time series started increasing at a relatively constant rate over one month, reaching a maximum of 19 gm-2d-1 one week before the onset of the submarine volcanic eruption. The H2S efflux time series at HIE07 showed a pulse in H2S emission just one day before the initiation of the submarine eruption, reaching peak values of 42 mg m-2 d-1, 10 times the average H2S efflux recorded during the observation period. Since CO2 and H2S effluxes are strongly influenced by external factors, we applied a multiple regression analysis to remove their contribution. A statistical analysis showed that the long-term trend of the filtered data is well correlated with the seismic energy. We find that these geochemical stations are important monitoring sites for evaluating the volcanic activity of El Hierro and that they demonstrate the potential of applying continuous monitoring of soil CO2 and H2S efflux to improve and optimize the detection of early warning signals of future volcanic unrest episodes at El Hierro. Continuous diffuse degassing studies would likely prove useful for monitoring other volcanoes during unrest episodes.

Real-time bicycle detection at signalized intersections using thermal imaging technology

Science.gov (United States)

Collaert, Robin

2013-02-01

More and more governments and authorities around the world are promoting the use of bicycles in cities, as this is healthy for the bicyclist and improves the quality of life in general. Safety and efficiency of bicyclists has become a major focus. To achieve this, there is a need for a smarter approach towards the control of signalized intersections. Various traditional detection technologies, such as video, microwave radar and electromagnetic loops, can be used to detect vehicles at signalized intersections, but none of these can consistently separate bikes from other traffic, day and night and in various weather conditions. As bikes should get a higher priority and also require longer green time to safely cross the signalized intersection, traffic managers are looking for alternative detection systems that can make the distinction between bicycles and other vehicles near the stop bar. In this paper, the drawbacks of a video-based approach are presented, next to the benefits of a thermal-video-based approach for vehicle presence detection with separation of bicycles. Also, the specific technical challenges are highlighted in developing a system that combines thermal image capturing, image processing and output triggering to the traffic light controller in near real-time and in a single housing.

The effect of thermal treatment on radiation-induced EPR signals in tooth enamel

International Nuclear Information System (INIS)

Vorona, I.P.; Ishchenko, S.S.; Baran, N.P.

2005-01-01

The effect of thermal treatment on the radiation-induced EPR spectrum of tooth enamel was studied. Annealing before sample irradiation was found to increase enamel radiation sensitivity by more than 40%. Depending on the annealing conditions the EPR signals of three supplementary radiation radicals were observed in addition to the main signal caused by CO 2 - radicals. It was found that the presence of these signals in the enamel EPR spectra provides evidence of sample annealing. The possibility of obtaining information about sample history by studying the additional EPR signals is discussed. It can be important to EPR dating and EPR dosimetry

One-dimensional modeling of thermal energy produced in a seismic fault

Science.gov (United States)

Konga, Guy Pascal; Koumetio, Fidèle; Yemele, David; Olivier Djiogang, Francis

2017-12-01

Generally, one observes an anomaly of temperature before a big earthquake. In this paper, we established the expression of thermal energy produced by friction forces between the walls of a seismic fault while considering the dynamic of a one-dimensional spring-block model. It is noted that, before the rupture of a seismic fault, displacements are caused by microseisms. The curves of variation of this thermal energy with time show that, for oscillatory and aperiodic displacement, the thermal energy is accumulated in the same way. The study reveals that thermal energy as well as temperature increases abruptly after a certain amount of time. We suggest that the corresponding time is the start of the anomaly of temperature observed which can be considered as precursory effect of a big seism. We suggest that the thermal energy can heat gases and dilate rocks until they crack. The warm gases can then pass through the cracks towards the surface. The cracks created by thermal energy can also contribute to the rupture of the seismic fault. We also suggest that the theoretical model of thermal energy, produced in seismic fault, associated with a large quantity of experimental data may help in the prediction of earthquakes.

Fabrication of a Micro-Needle Array Electrode by Thermal Drawing for Bio-Signals Monitoring.

Science.gov (United States)

Ren, Lei; Jiang, Qing; Chen, Keyun; Chen, Zhipeng; Pan, Chengfeng; Jiang, Lelun

2016-06-17

A novel micro-needle array electrode (MAE) fabricated by thermal drawing and coated with Ti/Au film was proposed for bio-signals monitoring. A simple and effective setup was employed to form glassy-state poly (lactic-co-glycolic acid) (PLGA) into a micro-needle array (MA) by the thermal drawing method. The MA was composed of 6 × 6 micro-needles with an average height of about 500 μm. Electrode-skin interface impedance (EII) was recorded as the insertion force was applied on the MAE. The insertion process of the MAE was also simulated by the finite element method. Results showed that MAE could insert into skin with a relatively low compression force and maintain stable contact impedance between the MAE and skin. Bio-signals, including electromyography (EMG), electrocardiography (ECG), and electroencephalograph (EEG) were also collected. Test results showed that the MAE could record EMG, ECG, and EEG signals with good fidelity in shape and amplitude in comparison with the commercial Ag/AgCl electrodes, which proves that MAE is an alternative electrode for bio-signals monitoring.

Fabrication of a Micro-Needle Array Electrode by Thermal Drawing for Bio-Signals Monitoring

Directory of Open Access Journals (Sweden)

Lei Ren

2016-06-01

Full Text Available A novel micro-needle array electrode (MAE fabricated by thermal drawing and coated with Ti/Au film was proposed for bio-signals monitoring. A simple and effective setup was employed to form glassy-state poly (lactic-co-glycolic acid (PLGA into a micro-needle array (MA by the thermal drawing method. The MA was composed of 6 × 6 micro-needles with an average height of about 500 μm. Electrode-skin interface impedance (EII was recorded as the insertion force was applied on the MAE. The insertion process of the MAE was also simulated by the finite element method. Results showed that MAE could insert into skin with a relatively low compression force and maintain stable contact impedance between the MAE and skin. Bio-signals, including electromyography (EMG, electrocardiography (ECG, and electroencephalograph (EEG were also collected. Test results showed that the MAE could record EMG, ECG, and EEG signals with good fidelity in shape and amplitude in comparison with the commercial Ag/AgCl electrodes, which proves that MAE is an alternative electrode for bio-signals monitoring.

Precursory changes in seismic velocity for the spectrum of earthquake failure modes

Science.gov (United States)

Scuderi, M.M.; Marone, C.; Tinti, E.; Di Stefano, G.; Collettini, C.

2016-01-01

Temporal changes in seismic velocity during the earthquake cycle have the potential to illuminate physical processes associated with fault weakening and connections between the range of fault slip behaviors including slow earthquakes, tremor and low frequency earthquakes1. Laboratory and theoretical studies predict changes in seismic velocity prior to earthquake failure2, however tectonic faults fail in a spectrum of modes and little is known about precursors for those modes3. Here we show that precursory changes of wave speed occur in laboratory faults for the complete spectrum of failure modes observed for tectonic faults. We systematically altered the stiffness of the loading system to reproduce the transition from slow to fast stick-slip and monitored ultrasonic wave speed during frictional sliding. We find systematic variations of elastic properties during the seismic cycle for both slow and fast earthquakes indicating similar physical mechanisms during rupture nucleation. Our data show that accelerated fault creep causes reduction of seismic velocity and elastic moduli during the preparatory phase preceding failure, which suggests that real time monitoring of active faults may be a means to detect earthquake precursors. PMID:27597879

A simple theoretical extension to the analysis of photothermal deflection signal for low thermal diffusivity evaluation

International Nuclear Information System (INIS)

Ravi, Jyotsna; Lekshmi, S.; Nair, K.P.R.; Rasheed, T.M.A

2004-01-01

A modified amplitude method to analyze the photothermal probe beam deflection signal for the determination of low thermal diffusivity values of materials is proposed. This simple theoretical model, which is an extension of the amplitude method proposed by Quelin et al., takes into account the dependence of the photothermal signal on the height of the probe beam above the sample surface which affects mirage measurements when the thermal diffusivity of the coupling medium is greater than that of the sample. The present work is similar to the modification to the phase method proposed by Bertolotti et al. for determination of low thermal diffusivity. The method can be applied irrespective of whether the sample is optically transparent or optically opaque and is independent of thickness

Thermal diffusivity effect in opto-thermal skin measurements

International Nuclear Information System (INIS)

Xiao, P; Imhof, R E; Cui, Y; Ciortea, L I; Berg, E P

2010-01-01

We present our latest study on the thermal diffusivity effect in opto-thermal skin measurements. We discuss how thermal diffusivity affects the shape of opto-thermal signal, and how to measure thermal diffusivity in opto-thermal measurements of arbitrary sample surfaces. We also present a mathematical model for a thermally gradient material, and its corresponding opto-thermal signal. Finally, we show some of our latest experimental results of this thermal diffusivity effect study.

Dose response, thermal stability and optical bleaching of the 310 degrees C isothermal TL signal in quartz

DEFF Research Database (Denmark)

Jain, Mayank; Duller, G.A.T.; Wintle, A.G.

2007-01-01

, thermal stability and the effects of optical bleaching. The (0-5s) signal shows all order of magnitude higher for saturation level with laboratory dose than the optically stimulated luminescence (OSL) signal, and has a thermal stability that is very sintilar to published values for the OSL or the 325...... degrees C TL peak. Bleaching with a solar simulator reduces both parts of the ITL signal to a low, but non-zero level in a few thousand seconds. This result is supported by an equivalent dose estimate oil a modern river sample from Zambia of 11 +/- 2 Gy. This combination of low residual dose and high...

Type III Nrg1 back signaling enhances functional TRPV1 along sensory axons contributing to basal and inflammatory thermal pain sensation.

Science.gov (United States)

Canetta, Sarah E; Luca, Edlira; Pertot, Elyse; Role, Lorna W; Talmage, David A

2011-01-01

Type III Nrg1, a member of the Nrg1 family of signaling proteins, is expressed in sensory neurons, where it can signal in a bi-directional manner via interactions with the ErbB family of receptor tyrosine kinases (ErbB RTKs). Type III Nrg1 signaling as a receptor (Type III Nrg1 back signaling) can acutely activate phosphatidylinositol-3-kinase (PtdIns3K) signaling, as well as regulate levels of α7* nicotinic acetylcholine receptors, along sensory axons. Transient receptor potential vanilloid 1 (TRPV1) is a cation-permeable ion channel found in primary sensory neurons that is necessary for the detection of thermal pain and for the development of thermal hypersensitivity to pain under inflammatory conditions. Cell surface expression of TRPV1 can be enhanced by activation of PtdIns3K, making it a potential target for regulation by Type III Nrg1. We now show that Type III Nrg1 signaling in sensory neurons affects functional axonal TRPV1 in a PtdIns3K-dependent manner. Furthermore, mice heterozygous for Type III Nrg1 have specific deficits in their ability to respond to noxious thermal stimuli and to develop capsaicin-induced thermal hypersensitivity to pain. Cumulatively, these results implicate Type III Nrg1 as a novel regulator of TRPV1 and a molecular mediator of nociceptive function.

Type III Nrg1 back signaling enhances functional TRPV1 along sensory axons contributing to basal and inflammatory thermal pain sensation.

Directory of Open Access Journals (Sweden)

Sarah E Canetta

Full Text Available Type III Nrg1, a member of the Nrg1 family of signaling proteins, is expressed in sensory neurons, where it can signal in a bi-directional manner via interactions with the ErbB family of receptor tyrosine kinases (ErbB RTKs. Type III Nrg1 signaling as a receptor (Type III Nrg1 back signaling can acutely activate phosphatidylinositol-3-kinase (PtdIns3K signaling, as well as regulate levels of α7* nicotinic acetylcholine receptors, along sensory axons. Transient receptor potential vanilloid 1 (TRPV1 is a cation-permeable ion channel found in primary sensory neurons that is necessary for the detection of thermal pain and for the development of thermal hypersensitivity to pain under inflammatory conditions. Cell surface expression of TRPV1 can be enhanced by activation of PtdIns3K, making it a potential target for regulation by Type III Nrg1. We now show that Type III Nrg1 signaling in sensory neurons affects functional axonal TRPV1 in a PtdIns3K-dependent manner. Furthermore, mice heterozygous for Type III Nrg1 have specific deficits in their ability to respond to noxious thermal stimuli and to develop capsaicin-induced thermal hypersensitivity to pain. Cumulatively, these results implicate Type III Nrg1 as a novel regulator of TRPV1 and a molecular mediator of nociceptive function.

Predicting earthquakes by analyzing accelerating precursory seismic activity

Science.gov (United States)

Varnes, D.J.

1989-01-01

During 11 sequences of earthquakes that in retrospect can be classed as foreshocks, the accelerating rate at which seismic moment is released follows, at least in part, a simple equation. This equation (1) is {Mathematical expression},where {Mathematical expression} is the cumulative sum until time, t, of the square roots of seismic moments of individual foreshocks computed from reported magnitudes;C and n are constants; and tfis a limiting time at which the rate of seismic moment accumulation becomes infinite. The possible time of a major foreshock or main shock, tf,is found by the best fit of equation (1), or its integral, to step-like plots of {Mathematical expression} versus time using successive estimates of tfin linearized regressions until the maximum coefficient of determination, r2,is obtained. Analyzed examples include sequences preceding earthquakes at Cremasta, Greece, 2/5/66; Haicheng, China 2/4/75; Oaxaca, Mexico, 11/29/78; Petatlan, Mexico, 3/14/79; and Central Chile, 3/3/85. In 29 estimates of main-shock time, made as the sequences developed, the errors in 20 were less than one-half and in 9 less than one tenth the time remaining between the time of the last data used and the main shock. Some precursory sequences, or parts of them, yield no solution. Two sequences appear to include in their first parts the aftershocks of a previous event; plots using the integral of equation (1) show that the sequences are easily separable into aftershock and foreshock segments. Synthetic seismic sequences of shocks at equal time intervals were constructed to follow equation (1), using four values of n. In each series the resulting distributions of magnitudes closely follow the linear Gutenberg-Richter relation log N=a-bM, and the product n times b for each series is the same constant. In various forms and for decades, equation (1) has been used successfully to predict failure times of stressed metals and ceramics, landslides in soil and rock slopes, and volcanic

Himawari-8 infrared observations of the June-August 2015 Mt Raung eruption, Indonesia

Science.gov (United States)

Kaneko, Takayuki; Takasaki, Kenji; Maeno, Fukashi; Wooster, Martin J.; Yasuda, Atsushi

2018-05-01

Volcanic activity involves processes that can change over short periods of time, which are sometimes closely related to the eruptive mode or the timing of its transitions. Eruptions bring high-temperature magma or gas to the surface; thermal observations of these eruptions can be used to determine the timeline of eruptive sequences or eruptive processes. In 2014, a new-generation meteorological satellite, Himawari-8, which carried a new sensor, the Advanced Himawari Imager (AHI), was launched. The AHI makes high-frequency infrared observations at a spatial resolution of 2 km during 10-min observation cycles. We analyzed an effusive eruption that occurred in 2015 at Mt Raung in Indonesia using these AHI images, which was the first attempt applying them to volcanological study. Based on the detailed analysis of the time-series variations in its thermal anomalies, this eruptive sequence was segmented into a Precursory Stage, Pulse 1, Pulse 2 and a Terminal Stage. Pulses 1 and 2 are effusive stages that exhibited a consecutive two-pulse pattern in their variations, reflecting changes in the lava effusion rate; the other stages are non-effusive. We were also able to determine the exact times of the onset and reactivation of lava flow effusion, as well as the precursory signals that preceded these events.

PI3K-AKT signaling pathway is involved in hypoxia/thermal-induced immunosuppression of small abalone Haliotis diversicolor.

Science.gov (United States)

Sun, Yulong; Zhang, Xin; Wang, Guodong; Lin, Shi; Zeng, Xinyang; Wang, Yilei; Zhang, Ziping

2016-12-01

The PI3K-AKT signal pathway has been found to be involved in many important physiological and pathological processes of the innate immune system of vertebrates and invertebrates. In this study, the AKT (HdAKT) and PI3K (HdPI3K) gene of small abalone Haliotis diversicolor were cloned and characterized for the important status of PI3K and AKT protein in PI3K-AKT signaling pathway. The full length cDNAs of HdAKT and HdPI3K are 2126 bp and 6052 bp respectively, encoding proteins of 479 amino acids and 1097 amino acids, respectively. The mRNA expression level of fourteen genes in the PI3K-AKT signaling pathway were detected by quantitative real-time PCR. The results showed that all these fourteen genes were ubiquitously expressed in seven selected tissues. Meanwhile, HdAKT was expressed in haemocytes with the highest expression level (p abalone. The mRNA expression of these genes in gills, haemocytes and hepatopancreas was significantly down-regulated after the Vibrio parahaemolyticus stimulation with environment stimulation (thermal, hypoxia and thermal & hypoxia). These results indicate that the dual/multiple stresses defeat the immune system and lead to immunosuppression in abalone. PI3K-AKT signaling pathway may be involved in hypoxia/thermal-induced immunosuppression of small abalone Haliotis diversicolor. Copyright © 2016 Elsevier Ltd. All rights reserved.

Quantitative mapping of precursory seismic quiescence before the 1989, M 7.1off-Sanriku earthquake, Japan

Directory of Open Access Journals (Sweden)

N. Umino

1999-06-01

Full Text Available The first main shock of the off-Sanriku earthquake sequence (02/11/89, M 7.1; 18/07/92, M 6.9; 28/12/94, M 7.5 was preceded by a precursory seismic quiescence lasting 2.5 ± 1 year and up to this main shock. The detailed properties of this quiescence were mapped as a function of time and space by a gridding technique using the ZMAP computer code, and the statistical significance was estimated by generating a synthetic catalog based on the microearthquake catalog of Tohoku University, which was the data set used. The statistically most significant expression of this precursory quiescence has a probability of 0.1% to have occurred at random and was located in the eastern part of the 1989 aftershock area, at a point to which the 1994 aftershocks extended also. If we define the dimensions of the quiescence anomaly by a vertical cylinder with the depth of the entire seismogenic layer, centered at the point of most significant quiescence and showing a rate decrease of 75%, then we find its radius is 25 ± 9 km. If we allow other shapes, such as the simplified aftershock volume of 1989, or other simple geometric figures, to define the rate decrease we find dimensions of 80 by 80 km. The characteristics of the quiescence anomaly do not depend strongly on the choice of free parameters within the following ranges: 100 ? number of events ? 400, 2.0 ? Mmin £ 3.0, 1 ? time window ? 3 years. With our method, a thorough analysis of the period before the 1994 main shock is not possible because of the interference of the extended aftershock sequence of 1989. Nevertheless, we identified a quiescence of nearly zero earthquakes located near the center of the 1994 aftershock area that lasted for one year up to that main shock. However, this quiescence period ranked only 46th in significance, behind other quiescences of equal duration and similar dimensions distributed in time and space through the data set. Because of the ubiquitous existence of periods of near

Discrete Scaling in Earthquake Precursory Phenomena: Evidence in the Kobe Earthquake, Japan

Science.gov (United States)

Johansen, Anders; Sornette, Didier; Wakita, Hiroshi; Tsunogai, Urumu; Newman, William I.; Saleur, Hubert

1996-10-01

We analyze the ion concentration of groundwater issuing from deep wells located near the epicenter of the recent earthquake of magnitude 6.9 near Kobe, Japan, on January 17, 1995. These concentrations are well fitted by log-periodic modulations around a leading power law. The exponent (real and imaginary parts) is very close to those already found for the fits of precursory seismic activity for Loma Prieta and the Aleutian Islands. This brings further support for the general hypothesis that complex critical exponents are a general phenomenon in irreversible self-organizing systems and particularly in rupture and earthquake phenomena. Nous analysons les fluctuations de concentrations ioniques de l'eau issue de puits profonds situés à proximité de l'épicentre du récent tremblement de terre de magnitude 6.9 proche de Kobe au Japon, le 17 janvier 1995. Ces fluctuations sont bien reproduites par des modulations log-périodiques autour d'une loi de puissance. Les parties réelle et imaginaire de l'exposant sont très proches de celles trouvées précédemment pour les tremblements de terre de Loma Prieta et des Iles Aléoutiennes. Ces résultats renforcent l'hypothèse que des exposants critiques complexes sont une propriété générale des phénomènes de croissance irréversible, et en particulier des problèmes de rupture et des tremblements de terre.

Theoretical Studies on the Physical and Environmental Factors Which Govern the Thermal Fading of Thermoluminescence Signal

International Nuclear Information System (INIS)

Rasheedy, M.S.; El-Sherif, M.A.; Hefni, M.A.

2008-01-01

Thermoluminescence solid-state detector is widely used to determine the dose in personnel and environmental monitoring for radiation protection purposes, for instance in the field of nuclear power production, medicine and research. However, thermal fading is a limiting factor for a long-term application, especially where temperature is changing significantly during the accumulation period. This paper studied the influence of temperature and duration of storage after irradiation on the thermal fading of the TL signal. Also, this paper discussed the dependence of the thermal fading on the trap parameters of TL glow peak. The most important parameters, which were considered here include the order of kinetics b, the depth of the trap level E (eV) and the frequency factor S (s-1). The dependence of the thermal fading on thermal stability parameters, namely trap depths and frequency factors for the glow peaks is discussed. The variation of the thermal fading as a function of the order of kinetics is demonstrated. In addition, this paper discussed the dependence of the thermal fading on the absorbed dose in case of first-, second- and general-order kinetics. The above-mentioned studies were arranged considering the models of first-, second- and general-order of kinetics

Acoustic signal recovery by thermal demodulation

Science.gov (United States)

Boullosa, R. R.; Santillán, Arturo O.

2006-10-01

One operating mode of recently developed thermoacoustic transducers is as an audio speaker that uses an input superimposed on a direct current; as a result, the audio signal occurs at the same frequency as the input signal. To extend the potential applications of these kinds of sources, the authors propose an alternative driving mode in which a simple thermoacoustic device, consisting of a metal film over a substrate and a heat sink, is excited with a high frequency sinusoid that is amplitude modulated by a lower frequency signal. They show that the modulating signal is recovered in the radiated waves due to a mechanism that is inherent to this type of thermoacoustic process. If the frequency of the carrier is higher than 30kHz and any modulating signal (the one of interest) is in the audio frequency range, only this signal will be heard. Thus, the thermoacoustic device operates as an audio-band, self-demodulating speaker.

Ultrasonic Sensor Signals and Optimum Path Forest Classifier for the Microstructural Characterization of Thermally-Aged Inconel 625 Alloy

Directory of Open Access Journals (Sweden)

Victor Hugo C. de Albuquerque

2015-05-01

Full Text Available Secondary phases, such as laves and carbides, are formed during the final solidification stages of nickel-based superalloy coatings deposited during the gas tungsten arc welding cold wire process. However, when aged at high temperatures, other phases can precipitate in the microstructure, like the γ'' and δ phases. This work presents an evaluation of the powerful optimum path forest (OPF classifier configured with six distance functions to classify background echo and backscattered ultrasonic signals from samples of the inconel 625 superalloy thermally aged at 650 and 950 \\(^\\circ\\C for 10, 100 and 200 h. The background echo and backscattered ultrasonic signals were acquired using transducers with frequencies of 4 and 5 MHz. The potentiality of ultrasonic sensor signals combined with the OPF to characterize the microstructures of an inconel 625 thermally aged and in the as-welded condition were confirmed by the results. The experimental results revealed that the OPF classifier is sufficiently fast (classification total time of 0.316 ms and accurate (accuracy of 88.75% and harmonic mean of 89.52 for the application proposed.

Ultrasonic sensor signals and optimum path forest classifier for the microstructural characterization of thermally-aged inconel 625 alloy.

Science.gov (United States)

de Albuquerque, Victor Hugo C; Barbosa, Cleisson V; Silva, Cleiton C; Moura, Elineudo P; Filho, Pedro P Rebouças; Papa, João P; Tavares, João Manuel R S

2015-05-27

Secondary phases, such as laves and carbides, are formed during the final solidification stages of nickel-based superalloy coatings deposited during the gas tungsten arc welding cold wire process. However, when aged at high temperatures, other phases can precipitate in the microstructure, like the γ'' and δ phases. This work presents an evaluation of the powerful optimum path forest (OPF) classifier configured with six distance functions to classify background echo and backscattered ultrasonic signals from samples of the inconel 625 superalloy thermally aged at 650 and 950 °C for 10, 100 and 200 h. The background echo and backscattered ultrasonic signals were acquired using transducers with frequencies of 4 and 5 MHz. The potentiality of ultrasonic sensor signals combined with the OPF to characterize the microstructures of an inconel 625 thermally aged and in the as-welded condition were confirmed by the results. The experimental results revealed that the OPF classifier is sufficiently fast (classification total time of 0.316 ms) and accurate (accuracy of 88.75%" and harmonic mean of 89.52) for the application proposed.

Microseismic Precursory Characteristics of Rock Burst Hazard in Mining Areas Near a Large Residual Coal Pillar: A Case Study from Xuzhuang Coal Mine, Xuzhou, China

Science.gov (United States)

Cao, An-ye; Dou, Lin-ming; Wang, Chang-bin; Yao, Xiao-xiao; Dong, Jing-yuan; Gu, Yu

2016-11-01

Identification of precursory characteristics is a key issue for rock burst prevention. The aim of this research is to provide a reference for assessing rock burst risk and determining potential rock burst risk areas in coal mining. In this work, the microseismic multidimensional information for the identification of rock bursts and spatial-temporal pre-warning was investigated in a specific coalface which suffered high rock burst risk in a mining area near a large residual coal pillar. Firstly, microseismicity evolution prior to a disastrous rock burst was qualitatively analysed, and the abnormal clustering of seismic sources, abnormal variations in daily total energy release, and event counts can be regarded as precursors to rock burst. Secondly, passive tomographic imaging has been used to locate high seismic activity zones and assess rock burst hazard when the coalface passes through residual pillar areas. The results show that high-velocity or velocity anomaly regions correlated well with strong seismic activities in future mining periods and that passive tomography has the potential to describe, both quantitatively and periodically, hazardous regions and assess rock burst risk. Finally, the bursting strain energy index was further used for short-term spatial-temporal pre-warning of rock bursts. The temporal sequence curve and spatial contour nephograms indicate that the status of the danger and the specific hazardous zones, and levels of rock burst risk can be quantitatively and rapidly analysed in short time and in space. The multidimensional precursory characteristic identification of rock bursts, including qualitative analysis, intermediate and short-time quantitative predictions, can guide the choice of measures implemented to control rock bursts in the field, and provides a new approach to monitor and forecast rock bursts in space and time.

Effects of Cyclic Thermal Load on the Signal Characteristics of FBG Sensors Packaged with Epoxy Adhesives

Energy Technology Data Exchange (ETDEWEB)

Kim, Heonyoung; Kang, Donghoon [Korea Railroad Research Institute, Uiwang (Korea, Republic of)

2017-04-15

Fiber optics sensors that have been mainly applied to aerospace areas are now finding applicability in other areas, such as transportation, including railways. Among the sensors, the fiber Bragg grating (FBG) sensors have led to a steep increase due to their properties of absolute measurement and multiplexing capability. Generally, the FBG sensors adhere to structures and sensing modules using adhesives such as an epoxy. However, the measurement errors that occurred when the FBG sensors were used in a long-term application, where they were exposed to environmental thermal load, required calibration. For this reason, the thermal curing of adhesives needs to be investigated to enhance the reliability of the FBG sensor system. This can be done at room temperature through cyclic thermal load tests using four types of specimens. From the test results, it is confirmed that residual compressive strain occurs to the FBG sensors due to an initial cyclic thermal load. In conclusion, signals of the FBG sensors need to be stabilized for applying them to a long-term SHM.

Thermal diffusivity imaging with the thermal lens microscope.

Science.gov (United States)

Dada, Oluwatosin O; Feist, Peter E; Dovichi, Norman J

2011-12-01

A coaxial thermal lens microscope was used to generate images based on both the absorbance and thermal diffusivity of histological samples. A pump beam was modulated at frequencies ranging from 50 kHz to 5 MHz using an acousto-optic modulator. The pump and a CW probe beam were combined with a dichroic mirror, directed into an inverted microscope, and focused onto the specimen. The change in the transmitted probe beam's center intensity was detected with a photodiode. The photodiode's signal and a reference signal from the modulator were sent to a high-speed lock-in amplifier. The in-phase and quadrature signals were recorded as a sample was translated through the focused beams and used to generate images based on the amplitude and phase of the lock-in amplifier's signal. The amplitude is related to the absorbance and the phase is related to the thermal diffusivity of the sample. Thin sections of stained liver and bone tissues were imaged; the contrast and signal-to-noise ratio of the phase image was highest at frequencies from 0.1-1 MHz and dropped at higher frequencies. The spatial resolution was 2.5 μm for both amplitude and phase images, limited by the pump beam spot size. © 2011 Optical Society of America

Thermal Radiometer Signal Processing Using Radiation Hard CMOS Application Specific Integrated Circuits for Use in Harsh Planetary Environments

Science.gov (United States)

Quilligan, G.; DuMonthier, J.; Aslam, S.; Lakew, B.; Kleyner, I.; Katz, R.

2015-01-01

Thermal radiometers such as proposed for the Europa Clipper flyby mission require low noise signal processing for thermal imaging with immunity to Total Ionizing Dose (TID) and Single Event Latchup (SEL). Described is a second generation Multi- Channel Digitizer (MCD2G) Application Specific Integrated Circuit (ASIC) that accurately digitizes up to 40 thermopile pixels with greater than 50 Mrad (Si) immunity TID and 174 MeV-sq cm/mg SEL. The MCD2G ASIC uses Radiation Hardened By Design (RHBD) techniques with a 180 nm CMOS process node.

Hsp90 orchestrates transcriptional regulation by Hsf1 and cell wall remodelling by MAPK signalling during thermal adaptation in a pathogenic yeast.

Directory of Open Access Journals (Sweden)

Michelle D Leach

2012-12-01

Full Text Available Thermal adaptation is essential in all organisms. In yeasts, the heat shock response is commanded by the heat shock transcription factor Hsf1. Here we have integrated unbiased genetic screens with directed molecular dissection to demonstrate that multiple signalling cascades contribute to thermal adaptation in the pathogenic yeast Candida albicans. We show that the molecular chaperone heat shock protein 90 (Hsp90 interacts with and down-regulates Hsf1 thereby modulating short term thermal adaptation. In the longer term, thermal adaptation depends on key MAP kinase signalling pathways that are associated with cell wall remodelling: the Hog1, Mkc1 and Cek1 pathways. We demonstrate that these pathways are differentially activated and display cross talk during heat shock. As a result ambient temperature significantly affects the resistance of C. albicans cells to cell wall stresses (Calcofluor White and Congo Red, but not osmotic stress (NaCl. We also show that the inactivation of MAP kinase signalling disrupts this cross talk between thermal and cell wall adaptation. Critically, Hsp90 coordinates this cross talk. Genetic and pharmacological inhibition of Hsp90 disrupts the Hsf1-Hsp90 regulatory circuit thereby disturbing HSP gene regulation and reducing the resistance of C. albicans to proteotoxic stresses. Hsp90 depletion also affects cell wall biogenesis by impairing the activation of its client proteins Mkc1 and Hog1, as well as Cek1, which we implicate as a new Hsp90 client in this study. Therefore Hsp90 modulates the short term Hsf1-mediated activation of the classic heat shock response, coordinating this response with long term thermal adaptation via Mkc1- Hog1- and Cek1-mediated cell wall remodelling.

Thermal signal propagation in soils in Romania: conductive and non-conductive processes

Directory of Open Access Journals (Sweden)

C. Demetrescu

2007-11-01

Full Text Available Temperature data recorded in 2002 and 2003 at 10 stations out of the 70 available in the Romanian automatic weather stations network are presented and analyzed in terms of the heat transfer from air to underground. The air temperature at 2 m, the soil temperatures at 0, 5, 10, 20, 50 and 100 cm below the surface as well as rain fall and snow cover thickness have been monitored. The selected locations sample various climate environments in Romania. Preliminary analytical modelling shows that soil temperatures track air temperature variations at certain locations and, consequently, the heat transfer is by conduction, while at other stations processes such as soil freezing and/or solar radiation heating play an important part in the heat flux balance at the air/soil interface. However, the propagation of the annual thermal signal in the uppermost one meter of soil is mainly by conduction; the inferred thermal diffusivity for 8 stations with continuous time series at all depth levels ranges from 3 to 10×10⁻⁷ m² s⁻¹.

Thermalization of squeezed states

International Nuclear Information System (INIS)

Solomon, Allan I

2005-01-01

Starting with a thermal squeezed state defined as a conventional thermal state based on an appropriate Hamiltonian, we show how an important physical property, the signal-to-noise ratio, is degraded, and propose a simple model of thermalization (Kraus thermalization)

Earthquake precursory events around epicenters and local active faults

Science.gov (United States)

Valizadeh Alvan, H.; Mansor, S. B.; Haydari Azad, F.

2013-05-01

shakes, mapping foreshocks and aftershocks, and following changes in the above-mentioned precursors prior to past earthquake instances all over the globe. Our analyses also encompass the geographical location and extents of local and regional faults which are considered as important factors during earthquakes. The co-analysis of direct and indirect observation for precursory events is considered as a promising method for possible future successful earthquake predictions. With proper and thorough knowledge about the geological setting, atmospheric factors and geodynamics of the earthquake-prone regions we will be able to identify anomalies due to seismic activity in the earth's crust.

Asymmetric thermal-relic dark matter. Sommerfeld-enhanced freeze-out, annihilation signals and unitarity bounds

International Nuclear Information System (INIS)

Baldes, Iason; Petraki, Kalliopi

2017-03-01

Dark matter that possesses a particle-antiparticle asymmetry and has thermalised in the early universe, requires a larger annihilation cross-section compared to symmetric dark matter, in order to deplete the dark antiparticles and account for the observed dark matter density. The annihilation cross-section determines the residual symmetric component of dark matter, which may give rise to annihilation signals during CMB and inside haloes today. We consider dark matter with long-range interactions, in particular dark matter coupled to a light vector or scalar force mediator. We compute the couplings required to attain a final antiparticle-to-particle ratio after the thermal freeze-out of the annihilation processes in the early universe, and then estimate the late-time annihilation signals. We show that, due to the Sommerfeld enhancement, highly asymmetric dark matter with long-range interactions can have a significant annihilation rate, potentially larger than symmetric dark matter of the same mass with contact interactions. We discuss caveats in this estimation, relating to the formation of stable bound states. Finally, we consider the non-relativistic partial-wave unitarity bound on the inelastic cross-section, we discuss why it can be realised only by long-range interactions, and showcase the importance of higher partial waves in this regime of large inelasticity. We derive upper bounds on the mass of symmetric and asymmetric thermal-relic dark matter for s-wave and p-wave annihilation, and exhibit how these bounds strengthen as the dark asymmetry increases.

Asymmetric thermal-relic dark matter: Sommerfeld-enhanced freeze-out, annihilation signals and unitarity bounds

Energy Technology Data Exchange (ETDEWEB)

Baldes, Iason [DESY, Notkestraße 85, Hamburg, D-22607 Germany (Germany); Petraki, Kalliopi, E-mail: iason.baldes@desy.de, E-mail: kpetraki@lpthe.jussieu.fr [Laboratoire de Physique Théorique et Hautes Energies (LPTHE), UMR 7589 CNRS and UPMC, 4 Place Jussieu, Paris, F-75252 France (France)

2017-09-01

Dark matter that possesses a particle-antiparticle asymmetry and has thermalised in the early universe, requires a larger annihilation cross-section compared to symmetric dark matter, in order to deplete the dark antiparticles and account for the observed dark matter density. The annihilation cross-section determines the residual symmetric component of dark matter, which may give rise to annihilation signals during CMB and inside haloes today. We consider dark matter with long-range interactions, in particular dark matter coupled to a light vector or scalar force mediator. We compute the couplings required to attain a final antiparticle-to-particle ratio after the thermal freeze-out of the annihilation processes in the early universe, and then estimate the late-time annihilation signals. We show that, due to the Sommerfeld enhancement, highly asymmetric dark matter with long-range interactions can have a significant annihilation rate, potentially larger than symmetric dark matter of the same mass with contact interactions. We discuss caveats in this estimation, relating to the formation of stable bound states. Finally, we consider the non-relativistic partial-wave unitarity bound on the inelastic cross-section, we discuss why it can be realised only by long-range interactions, and showcase the importance of higher partial waves in this regime of large inelasticity. We derive upper bounds on the mass of symmetric and asymmetric thermal-relic dark matter for s -wave and p -wave annihilation, and exhibit how these bounds strengthen as the dark asymmetry increases.

Asymmetric thermal-relic dark matter. Sommerfeld-enhanced freeze-out, annihilation signals and unitarity bounds

Energy Technology Data Exchange (ETDEWEB)

Baldes, Iason [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Petraki, Kalliopi [Nationaal Instuut voor Kernfysica en Hoge-Energiefysica (NIKHEF), Amsterdam (Netherlands); UMR 7589 CNRS et UPMC, Paris (France). Laboratoire de Physique Theorique et Hautes Energies (LPTHE)

2017-03-15

Dark matter that possesses a particle-antiparticle asymmetry and has thermalised in the early universe, requires a larger annihilation cross-section compared to symmetric dark matter, in order to deplete the dark antiparticles and account for the observed dark matter density. The annihilation cross-section determines the residual symmetric component of dark matter, which may give rise to annihilation signals during CMB and inside haloes today. We consider dark matter with long-range interactions, in particular dark matter coupled to a light vector or scalar force mediator. We compute the couplings required to attain a final antiparticle-to-particle ratio after the thermal freeze-out of the annihilation processes in the early universe, and then estimate the late-time annihilation signals. We show that, due to the Sommerfeld enhancement, highly asymmetric dark matter with long-range interactions can have a significant annihilation rate, potentially larger than symmetric dark matter of the same mass with contact interactions. We discuss caveats in this estimation, relating to the formation of stable bound states. Finally, we consider the non-relativistic partial-wave unitarity bound on the inelastic cross-section, we discuss why it can be realised only by long-range interactions, and showcase the importance of higher partial waves in this regime of large inelasticity. We derive upper bounds on the mass of symmetric and asymmetric thermal-relic dark matter for s-wave and p-wave annihilation, and exhibit how these bounds strengthen as the dark asymmetry increases.

Asymmetric thermal-relic dark matter: Sommerfeld-enhanced freeze-out, annihilation signals and unitarity bounds

International Nuclear Information System (INIS)

Baldes, Iason; Petraki, Kalliopi

2017-01-01

Dark matter that possesses a particle-antiparticle asymmetry and has thermalised in the early universe, requires a larger annihilation cross-section compared to symmetric dark matter, in order to deplete the dark antiparticles and account for the observed dark matter density. The annihilation cross-section determines the residual symmetric component of dark matter, which may give rise to annihilation signals during CMB and inside haloes today. We consider dark matter with long-range interactions, in particular dark matter coupled to a light vector or scalar force mediator. We compute the couplings required to attain a final antiparticle-to-particle ratio after the thermal freeze-out of the annihilation processes in the early universe, and then estimate the late-time annihilation signals. We show that, due to the Sommerfeld enhancement, highly asymmetric dark matter with long-range interactions can have a significant annihilation rate, potentially larger than symmetric dark matter of the same mass with contact interactions. We discuss caveats in this estimation, relating to the formation of stable bound states. Finally, we consider the non-relativistic partial-wave unitarity bound on the inelastic cross-section, we discuss why it can be realised only by long-range interactions, and showcase the importance of higher partial waves in this regime of large inelasticity. We derive upper bounds on the mass of symmetric and asymmetric thermal-relic dark matter for s -wave and p -wave annihilation, and exhibit how these bounds strengthen as the dark asymmetry increases.

Earthquake forecasting studies using radon time series data in Taiwan

Science.gov (United States)

Walia, Vivek; Kumar, Arvind; Fu, Ching-Chou; Lin, Shih-Jung; Chou, Kuang-Wu; Wen, Kuo-Liang; Chen, Cheng-Hong

2017-04-01

For few decades, growing number of studies have shown usefulness of data in the field of seismogeochemistry interpreted as geochemical precursory signals for impending earthquakes and radon is idendified to be as one of the most reliable geochemical precursor. Radon is recognized as short-term precursor and is being monitored in many countries. This study is aimed at developing an effective earthquake forecasting system by inspecting long term radon time series data. The data is obtained from a network of radon monitoring stations eastblished along different faults of Taiwan. The continuous time series radon data for earthquake studies have been recorded and some significant variations associated with strong earthquakes have been observed. The data is also examined to evaluate earthquake precursory signals against environmental factors. An automated real-time database operating system has been developed recently to improve the data processing for earthquake precursory studies. In addition, the study is aimed at the appraisal and filtrations of these environmental parameters, in order to create a real-time database that helps our earthquake precursory study. In recent years, automatic operating real-time database has been developed using R, an open source programming language, to carry out statistical computation on the data. To integrate our data with our working procedure, we use the popular and famous open source web application solution, AMP (Apache, MySQL, and PHP), creating a website that could effectively show and help us manage the real-time database.

Multi-Parameter Observation and Detection of Pre-Earthquake Signals in Seismically Active Areas

Science.gov (United States)

Ouzounov, D.; Pulinets, S.; Parrot, M.; Liu, J. Y.; Hattori, K.; Kafatos, M.; Taylor, P.

2012-01-01

The recent large earthquakes (M9.0 Tohoku, 03/2011; M7.0 Haiti, 01/2010; M6.7 L Aquila, 04/2008; and M7.9 Wenchuan 05/2008) have renewed interest in pre-anomalous seismic signals associated with them. Recent workshops (DEMETER 2006, 2011 and VESTO 2009 ) have shown that there were precursory atmospheric /ionospheric signals observed in space prior to these events. Our initial results indicate that no single pre-earthquake observation (seismic, magnetic field, electric field, thermal infrared [TIR], or GPS/TEC) can provide a consistent and successful global scale early warning. This is most likely due to complexity and chaotic nature of earthquakes and the limitation in existing ground (temporal/spatial) and global satellite observations. In this study we analyze preseismic temporal and spatial variations (gas/radon counting rate, atmospheric temperature and humidity change, long-wave radiation transitions and ionospheric electron density/plasma variations) which we propose occur before the onset of major earthquakes:. We propose an Integrated Space -- Terrestrial Framework (ISTF), as a different approach for revealing pre-earthquake phenomena in seismically active areas. ISTF is a sensor web of a coordinated observation infrastructure employing multiple sensors that are distributed on one or more platforms; data from satellite sensors (Terra, Aqua, POES, DEMETER and others) and ground observations, e.g., Global Positioning System, Total Electron Content (GPS/TEC). As a theoretical guide we use the Lithosphere-Atmosphere-Ionosphere Coupling (LAIC) model to explain the generation of multiple earthquake precursors. Using our methodology, we evaluated retrospectively the signals preceding the most devastated earthquakes during 2005-2011. We observed a correlation between both atmospheric and ionospheric anomalies preceding most of these earthquakes. The second phase of our validation include systematic retrospective analysis for more than 100 major earthquakes (M>5

Studies of the thermal dissolution process of the Suzuki phase of the Eu2+ ion in KBr single crystals by analysis of photoacoustic signals

International Nuclear Information System (INIS)

MejIa-Uriarte, E V; Castaneda-Guzman, R; Villagran-Muniz, M; Camarillo, E; A, J Hernandez; S, H Murrieta; Navarrete, M

2003-01-01

An experimental investigation of the thermal behaviour of the dissolution process of the Suzuki phase (SP) by continuous heating (1 deg. C min -1 ) of KBr:Eu 2+ crystals is reported in this work. The thermal profiles were determined by the correlation functions between subsequent photoacoustic (PA) signals registered during the dissolution process. The behaviour of the thermal profile is directly related to the absorption coefficient of the Eu 2+ ion in precipitated states that are present in the crystal. The PA signal is detected as a consequence of the non-radiative processes that take place after the excitation of the low-energy band of the Eu 2+ ion by means of a focused laser pulse at 355 nm. The results obtained by this method are compared with those simultaneously obtained by the photoluminescence (PL) technique. The samples were heated from room temperature to 205 deg. C. The PA signal and PL spectrum were obtained every 6 deg. C. The temperature range of the SP dissolution process was from 77 to 115 deg. C. These results are in agreement with those obtained by the PL technique and with the data reported in the literature

Formation of the image on the receiver of thermal radiation

Science.gov (United States)

Akimenko, Tatiana A.

2018-04-01

The formation of the thermal picture of the observed scene with the verification of the quality of the thermal images obtained is one of the important stages of the technological process that determine the quality of the thermal imaging observation system. In this article propose to consider a model for the formation of a thermal picture of a scene, which must take into account: the features of the object of observation as the source of the signal; signal transmission through the physical elements of the thermal imaging system that produce signal processing at the optical, photoelectronic and electronic stages, which determines the final parameters of the signal and its compliance with the requirements for thermal information and measurement systems.

Temperature Modulated Nanomechanical Thermal Analysis

DEFF Research Database (Denmark)

Alves, Gustavo Marcati A.; Bose-Goswami, Sanjukta; Mansano, Ronaldo D.

2018-01-01

The response of microcantilever deflection to complex heating profiles was used to study thermal events like glass transition and enthalpy relaxation on nanograms of the biopolymer Poly(lactic-co-glycolic acid) (PLGA). The use of two heating rates enables the separation of effects on the deflection...... response that depends on previous thermal history (non-reversing signal) and effects that depends only on the heating rate variation (reversing signal). As these effects may appear superposed in the total response, temperature modulation can increase the measurement sensitivity to some thermal events when...

Analysis of the sensitivity and sample-furnace thermal-lag of a differential thermal analyzer

International Nuclear Information System (INIS)

Roura, P.; Farjas, J.

2005-01-01

The heat exchange between the horizontal furnace of a differential thermal analyzer (DTA) and the sample is analyzed with the aim of understanding the parameters governing the thermal signal. The resistance due to radiation and conduction through the gas has been calculated and compared to the experimental values of the thermal-lag between the sample and furnace and apparatus sensitivity. The overall evolution of these parameters with the temperature and their relative values are well understood by considering the temperature differences that arise between the sample and holder. Two RC thermal models are used for describing the apparatus performance at different temperature ranges. Finally, the possibility of improving the signal quality through the control of the leak resistances is stressed

Study and development of new dosemeters for thermal neutrons

International Nuclear Information System (INIS)

Urena N, F.

1998-01-01

An alanine-boron compound, alanine hydroborate, was synthesized and chemically characterized to be used for thermal neutrons fluence measurements. The synthesis of the compound was made by reacting the amino acid alanine with boric acid in three different media: acidic, neutral and alkaline. Physicochemical analysis showed that the alkaline medium is favorable for the synthesis of the alanine hydroborate. The compound was evaluated as a thermal neutron fluence detector by the detection of the free radical yield upon neutron thermal irradiation by Electron Paramagnetic Resonance (EPR). The present work also studies the EPR-signal response of the three preparations to thermal neutron irradiation (φ = 5 x 10 7 n/cm 2 -s). The following EPR signal parameters of the samples were investigated: peak-to-peak signal intensity vs. thermal neutron fluence Φ = φ Δt ; where Δt = 1, 5, 10, 20, 40, 60, 80, 90, 100, 110 and 120 h. , peak-to-peak signal intensity vs. microwave power, signal fading; repeatability, batch homogeneity, stability and zero dose response. It is concluded that these new products could be used in thermal neutron fluence estimations. (Author)

Advanced Signal Processing for Thermal Flaw Detection; TOPICAL

International Nuclear Information System (INIS)

VALLEY, MICHAEL T.; HANSCHE, BRUCE D.; PAEZ, THOMAS L.; URBINA, ANGEL; ASHBAUGH, DENNIS M.

2001-01-01

Dynamic thermography is a promising technology for inspecting metallic and composite structures used in high-consequence industries. However, the reliability and inspection sensitivity of this technology has historically been limited by the need for extensive operator experience and the use of human judgment and visual acuity to detect flaws in the large volume of infrared image data collected. To overcome these limitations new automated data analysis algorithms and software is needed. The primary objectives of this research effort were to develop a data processing methodology that is tied to the underlying physics, which reduces or removes the data interpretation requirements, and which eliminates the need to look at significant numbers of data frames to determine if a flaw is present. Considering the strengths and weakness of previous research efforts, this research elected to couple both the temporal and spatial attributes of the surface temperature. Of the possible algorithms investigated, the best performing was a radiance weighted root mean square Laplacian metric that included a multiplicative surface effect correction factor and a novel spatio-temporal parametric model for data smoothing. This metric demonstrated the potential for detecting flaws smaller than 0.075 inch in inspection areas on the order of one square foot. Included in this report is the development of a thermal imaging model, a weighted least squares thermal data smoothing algorithm, simulation and experimental flaw detection results, and an overview of the ATAC (Automated Thermal Analysis Code) software that was developed to analyze thermal inspection data

Landslide precursory deformation interpretation using ALOS-2/PALSAR-2 InSAR image along Min River in Maoxien, Sichuan Province, China

Science.gov (United States)

Sato, H. P.

2017-12-01

Maoxien area in Sichuan Province, China has many landslide. For example, landslide (rock avalanche) occurred on the slope in Xinmocun Village in Maoxeien on 24 June 2017. I produced and interpreetd InSAR image using ALOS/PALSAR data observed on 19 Jul 2007-3 Sep 2007 and on 27 Jan 2011-14 Mar 2011, and ALOS-2/PALSAR-2 data observed on 26 Jul 2015-13 Dec 2015 and on 13 Dec 2015-11 Dec 2016. These images give good coherence and it was easy to identify local landslide surface deformation. As a result, e.g., two slopes were estimated to have local landslide surface deformation; one is at 103.936587 deg E and 32.04462 deg N, another is at 103.674754 deg E and 31.852838 N. However, the slope in Xinmocun Village was not identified as landslide precursory deformation. In the poster I will present more InSAR image observed after 11 Dec 2016 and discuss the possibility of local landslide surface deformaton using InSAR image. ALOS/PALSAR and ALOS-2/PALSAR-2 data were provided by JAXA through Landslide Working Group in JAXA and through Special Research 2015-B-02 of Earthquake Research Institute/Tokyo University. This study was supported by KAKENHI (17H02973).

Signal processing for liquid ionization calorimeters

International Nuclear Information System (INIS)

Cleland, W.E.; Stern, E.G.

1992-01-01

We present the results of a study of the effects of thermal and pileup noise in liquid ionization calorimeters operating in a high luminosity calorimeters operating in a high luminosity environment. The method of optimal filtering of multiply-sampled signals which may be used to improve the timing and amplitude resolution of calorimeter signals is described, and its implications for signal shaping functions are examined. The dependence of the time and amplitude resolution on the relative strength of the pileup and thermal noise, which varies with such parameters as luminosity, rapidity and calorimeter cell size, is examined

Investigation of typicality of non-nuclear rod and fuel-clad gap effect during reflood phase, and development of a FEM thermal transient analysis code HETFEM

International Nuclear Information System (INIS)

Sudoh, Takashi

1981-06-01

The objective of this study are: 1) Evaluate the capability of the electrical heater for simulating the fuel rod during the reflood phase, and 2) To investigate the effect of the clad-fuel gap in the fuel rod on the clad thermal response during the reflood phase. A computer code HETFEM which is the two dimensional transient thermal conductivity analysis code utilized a finite element method is developed for analysing thermal responses of heater and fuel rod. The two kinds of electrical heaters and a fuel rod are calculated with simple boundary conditions. 1) direct heater (former JAERI reflood test heater), 2) indirect heater (FLECHT test heater), 3) fuel rod (15 x 15 type in Westinghouse PWR). The comparison of the clad temperature responses shows the quench time is influenced by the thermal diffusivity and gap conductance. In the conclusion, the ELECHT heater shows atypicality in the clad temperature response and heat releasing rate. But the direct heater responses are similar to those of the fuel rod. For the gap effect on the fuel rod behavior, the lower gap conductance causes sooner quench and less heat releasing rate. This calculation is not considered the precursory cooling which is affected by heat releasing rate at near and below the quench front. Therefore two dimensional calculation with heat transfer related to the local fluid conditions will be needed. (author)

Generating a representative signal of coal ash content to anticipate combustion control in a thermal power station

International Nuclear Information System (INIS)

Prieto-Fernandez, Ismael; Santurio-Diaz, J.M.; Folgueras-Diaz, B.; Lopez-Bobo, M. Rosario; Fernandez-Viar, P.

2004-01-01

This paper describes the possibilities of continuously measuring coal ash in the boiler feeding circuit of a thermal power station so that the measurement can be used as a signal for the boiler combustion control system. An installation was designed, at semi-industrial scale, that could faithfully reproduce the operation of a belt feeder. In order to measure the ash content, a natural radioactivity meter was installed and a large number of coal samples with different ranks and grain sizes were tested, eventually showing the possibility of achieving the objective

Galaxy Cluster Outskirts from the Thermal SZ and Non-Thermal Synchrotron Link

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Kaustuv Basu

2016-11-01

Full Text Available Galaxy cluster merger shocks are the main agent for the thermalization of the intracluster medium and the energization of cosmic ray particles in it. Shock propagation changes the state of the tenuous intracluster plasma, and the corresponding signal variations are measurable with the current generation of X-ray and Sunyaev–Zel’dovich (SZ effect instruments. Additionally, non-thermal electrons (re-energized by the shocks sometimes give rise to extended and luminous synchrotron sources known as radio relics, which are prominent indicators of shocks propagating roughly in the plane of the sky. In this short review, we discuss how the joint modeling of the non-thermal and thermal signal variations across radio relic shock fronts is helping to advance our knowledge of the gas thermodynamical properties and magnetic field strengths in the cluster outskirts. We describe the first use of the SZ effect to measure the Mach numbers of relic shocks, for both the nearest (Coma and the farthest (El Gordo clusters with known radio relics.

Thermal induced EPR signals in tooth enamel

International Nuclear Information System (INIS)

Fattibene, P.; Aragno, D.; Onori, S.; Pressello, M.C.

2000-01-01

Electron paramagnetic resonance (EPR) spectroscopy was used to detect the effects of temperature on powdered human tooth enamel, not irradiated in the laboratory. Samples were heated at temperature between 350 and 450, at 600 and at 1000 deg. C, for different heating times, between 6 min and 39 h. Changes in the EPR spectra were detected, with the formation of new signals. Possible correlation between the changes in EPR spectra and modifications in the enamel and in the mineral phase of bone detected with other techniques is discussed. The implications for dosimetric applications of signals induced by overheating due to mechanical friction during sample preparation are underlined

Thermal margin control

International Nuclear Information System (INIS)

Musick, C.R.

1976-01-01

A monitoring system is described for providing warning and/or trip signals indicative of the approach of the operating conditions of a nuclear steam supply system to a departure from nucleate boiling or coolant temperature saturation. The invention is characterized by calculation of the thermal limit locus in response to signals which accurately represent reactor cold leg temperature and core power, the core power signal being adjusted to compensate for the effects of both radial and axial peaking factor. 37 claims, 3 figures

Research on Debonding Defects in Thermal Barrier Coatings Structure by Thermal-Wave Radar Imaging (TWRI)

Science.gov (United States)

Wang, Fei; Liu, Junyan; Mohummad, Oliullah; Wang, Yang

2018-06-01

In this paper, thermal-wave radar imaging (TWRI) is introduced to detect debonding defects in SiC-coated Ni-based superalloy plates. Linear frequency modulation signal (chirp) is used as the excitation signal which has a large time-bandwidth product. Artificial debonding defects in SiC coating are excited by the laser beam with the light intensity modulated by a chirp signal. Cross-correlation algorithm and chirp lock-in algorithm are introduced to extract the thermal-wave signal characteristic. The comparative experiment between TWRI reflection mode and transmission mode was carried out. Experiments are conducted to investigate the influence of laser power density, chirp period, and excitation frequency. Experimental results illustrate that chirp lock-in phase has a better detection capability than other characteristic parameters. TWRI can effectively detect simulated debonding defects of SiC-coated Ni-based superalloy plates.

Biomedical signals and systems

CERN Document Server

Tranquillo, Joseph V

2013-01-01

Biomedical Signals and Systems is meant to accompany a one-semester undergraduate signals and systems course. It may also serve as a quick-start for graduate students or faculty interested in how signals and systems techniques can be applied to living systems. The biological nature of the examples allows for systems thinking to be applied to electrical, mechanical, fluid, chemical, thermal and even optical systems. Each chapter focuses on a topic from classic signals and systems theory: System block diagrams, mathematical models, transforms, stability, feedback, system response, control, time

A phenomenological model of thermal-hydraulics of convective boiling during the quenching of hot rod bundles

International Nuclear Information System (INIS)

Unal, C.; Nelson, R.

1991-01-01

After completion of the thermal-hydraulic model developed in a companion paper, the authors performed developmental assessment calculation of the model using steady-state and transient post-critical heat flux (CHF) data. This paper discusses the results of those calculations. The overall interfacial drag model predicted reasonable drag coefficients for both the nucleate boiling and the inverted annular flow (IAF) regimes. The predicted pressure drops agreed reasonably well with the measured data of two transient experiments, CCTF Run 14 and a Lehigh reflood test. The thermal-hydraulic model for post-CHF convective heat transfer predicted the rewetting velocities reasonably well for both experiments. The predicted average slope of the wall temperature traces for these tests showed reasonable agreement with the measured data, indicating that the transient-calculated precursory cooling rates agreed with measured data. The hot-patch model, in conjunction with the other thermal-hydraulic models, was capable of modeling the Winfrith post-CHF hot-patch experiments. The hot-patch model kept the wall temperatures at the specified levels in the hot-patch regions and did not allow any quench-front propagation from either the bottom or the top of the test section. The interfacial heat-transfer model tended to slightly underpredict the vapor temperatures. The maximum difference between calculated and measured vapor temperatures was 20%, with a 10% difference for the remainder of the runs considered. The wall-to-fluid heat transfer was predicted reasonably well, and the predicted wall temperatures were in reasonable agreement with measured data with a maximum relative error of less than 13%

Generating a representative signal of coal moisture content to anticipate combustion control in thermal power stations

Energy Technology Data Exchange (ETDEWEB)

Prieto-Fernandez, Ismael; Luengo-Garcia, J. Carlos; Alonso-Hidalgo, Manuela; Ponte-Gutierrez, Daniel [Area de Maquinas y Motores Termicos, Universidad de Oviedo, Campus Universitario s/n 33203, Asturias Gijon (Spain)

2002-06-01

This article describes the possibilities of continuously measuring coal moisture in the boiler feeding circuit of a thermal power station so that the measurement can be used as a signal for the boiler combustion control system. To do so, in the first place, the point through which coal would be fed into the boiler was chosen. After studying the different parts of the circuit, the feeder was selected. Then, an installation was designed, at semi-industrial scale, faithfully reproducing the operation of a belt conveyor. In order to measure the moisture content, a microwave system was installed, and a large number of coal samples with different ranks and grain sizes was tested showing eventually the likelihood of the objective.

Detection of ionospheric perturbations associated with Japanese earthquakes on the basis of reception of LF transmitter signals on the satellite DEMETER

Directory of Open Access Journals (Sweden)

F. Muto

2008-02-01

Full Text Available There have been recently reported a lot of electromagnetic phenomena associated with earthquakes (EQs. Among these, the ground-based reception of subionospheric waves from VLF/LF transmitters, is recognized as a promising tool to investigate the ionospheric perturbations associated with EQs. This paper deals with the corresponding whistler-mode signals in the upper ionosphere from those VLF/LF transmitters, which is the counterpart of subionospheric signals. The whistler-mode VLF/LF transmitter signals are detected on board the French satellite, DEMETER launched on 29 June 2004. We have chosen several large Japanese EQs including the Miyagi-oki EQ (16 August 2005; M=7.2, depth=36 km, and the target transmitter is a Japanese LF transmitter (JJY whose transmitter frequency is 40 kHz. Due to large longitudinal separation of each satellite orbit (2500 km, we have to adopt a statistical analysis over a rather long period (such as 3 weeks or one month to have reliable data set. By analyzing the spatial distribution of JJY signal intensity (in the form of signal to noise ratio SNR during a period of 4 months including the Miyagi-oki EQ, we have found significant changes in the intensity; generally the SNR is significantly depleted before the EQ, which is considered to be a precursory ionospheric signature of the EQ. This abnormal effect is reasonably explained in terms of either (1 enhanced absorption of whistler-mode LF signals in the lower ionosphere due to the lowering of the lower ionosphere, or (2 nonlinear wave-wave scattering. Finally, this analysis suggests an important role of satellite observation in the study of lithosphere-atmosphere-ionosphere coupling.

Thermal heat-balance mode flow-to-frequency converter

Science.gov (United States)

Pawlowski, Eligiusz

2016-11-01

This paper presents new type of thermal flow converter with the pulse frequency output. The integrating properties of the temperature sensor have been used, which allowed for realization of pulse frequency modulator with thermal feedback loop, stabilizing temperature of sensor placed in the flowing medium. The system assures balancing of heat amount supplied in impulses to the sensor and heat given up by the sensor in a continuous way to the flowing medium. Therefore the frequency of output impulses is proportional to the heat transfer coefficient from sensor to environment. According to the King's law, the frequency of those impulses is a function of medium flow velocity around the sensor. The special feature of presented solution is total integration of thermal sensor with the measurement signal conditioning system. Sensor and conditioning system are not the separate elements of the measurement circuit, but constitute a whole in form of thermal heat-balance mode flow-to-frequency converter. The advantage of such system is easiness of converting the frequency signal to the digital form, without using any additional analogue-to-digital converters. The frequency signal from the converter may be directly connected to the microprocessor input, which with use of standard built-in counters may convert the frequency into numerical value of high precision. Moreover, the frequency signal has higher resistance to interference than the voltage signal and may be transmitted to remote locations without the information loss.

Optoacoustic detection of thermal lesions

Science.gov (United States)

Arsenault, Michel G.; Kolios, Michael C.; Whelan, William M.

2009-02-01

Minimally invasive thermal therapy is being investigated as an alternative cancer treatment. It involves heating tissues to greater than 55°C over a period of a few minutes, which results in tissue coagulation. Optoacoustic (OA) imaging is a new imaging technique that involves exposing tissues to pulsed light and detecting the acoustic waves that are generated. In this study, adult bovine liver tissue samples were heated using continuous wave laser energy for various times, then scanned using an optoacoustic imaging system. Large optoacoustic signal variability was observed in the native tissue prior to heating. OA signal amplitude increased with maximum tissue temperature achieved, characterized by a correlation coefficient of 0.63. In this study we show that there are detectable changes in optoacoustic signal strength that arise from tissue coagulation, which demonstrates the potential of optoacoustic technology for the monitoring of thermal therapy delivery.

Deciphering neuronal population codes for acute thermal pain

Science.gov (United States)

Chen, Zhe; Zhang, Qiaosheng; Phuong Sieu Tong, Ai; Manders, Toby R.; Wang, Jing

2017-06-01

Objective. Pain is defined as an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage. Current pain research mostly focuses on molecular and synaptic changes at the spinal and peripheral levels. However, a complete understanding of pain mechanisms requires the physiological study of the neocortex. Our goal is to apply a neural decoding approach to read out the onset of acute thermal pain signals, which can be used for brain-machine interface. Approach. We used micro wire arrays to record ensemble neuronal activities from the primary somatosensory cortex (S1) and anterior cingulate cortex (ACC) in freely behaving rats. We further investigated neural codes for acute thermal pain at both single-cell and population levels. To detect the onset of acute thermal pain signals, we developed a novel latent state-space framework to decipher the sorted or unsorted S1 and ACC ensemble spike activities, which reveal information about the onset of pain signals. Main results. The state space analysis allows us to uncover a latent state process that drives the observed ensemble spike activity, and to further detect the ‘neuronal threshold’ for acute thermal pain on a single-trial basis. Our method achieved good detection performance in sensitivity and specificity. In addition, our results suggested that an optimal strategy for detecting the onset of acute thermal pain signals may be based on combined evidence from S1 and ACC population codes. Significance. Our study is the first to detect the onset of acute pain signals based on neuronal ensemble spike activity. It is important from a mechanistic viewpoint as it relates to the significance of S1 and ACC activities in the regulation of the acute pain onset.

Monitoring Streambed Scour/Deposition Under Nonideal Temperature Signal and Flood Conditions

Science.gov (United States)

DeWeese, Timothy; Tonina, Daniele; Luce, Charles

2017-12-01

Streambed erosion and deposition are fundamental geomorphic processes in riverbeds, and monitoring their evolution is important for ecological system management and in-stream infrastructure stability. Previous research showed proof of concept that analysis of paired temperature signals of stream and pore waters can simultaneously provide monitoring scour and deposition, stream sediment thermal regime, and seepage velocity information. However, it did not address challenges often associated with natural systems, including nonideal temperature variations (low-amplitude, nonsinusoidal signal, and vertical thermal gradients) and natural flooding conditions on monitoring scour and deposition processes over time. Here we addressed this knowledge gap by testing the proposed thermal scour-deposition chain (TSDC) methodology, with laboratory experiments to test the impact of nonideal temperature signals under a range of seepage velocities and with a field application during a pulse flood. Both analyses showed excellent match between surveyed and temperature-derived bed elevation changes even under very low temperature signal amplitudes (less than 1°C), nonideal signal shape (sawtooth shape), and strong and changing vertical thermal gradients (4°C/m). Root-mean-square errors on predicting the change in streambed elevations were comparable with the median grain size of the streambed sediment. Future research should focus on improved techniques for temperature signal phase and amplitude extractions, as well as TSDC applications over long periods spanning entire hydrographs.

The Measurement of Thermal Diffusivity in Conductor and Insulator by Photodeflection Technique

Science.gov (United States)

Achathongsuk, U.; Rittidach, T.; Tipmonta, P.; Kijamnajsuk, P.; Chotikaprakhan, S.

2017-09-01

The purpose of this study is to estimate thermal diffusivities of high thermal diffusivity bulk material as well as low thermal diffusivity bulk material by using many types of fluid such as Ethyl alcohol and water. This method is studied by measuring amplitude and phase of photodeflection signal in various frequency modulations. The experimental setup consists of two laser lines: 1) a pump laser beams through a modulator, varied frequency, controlled by lock-in amplifier and focused on sample surface by lens. 2) a probe laser which parallels with the sample surface and is perpendicular to the pump laser beam. The probe laser deflection signal is obtained by a position sensor which controlled by lock-in amplifier. Thermal diffusivity is calculated by measuring the amplitude and phase of the photodeflection signal and compared with the thermal diffusivity of a standard value. The thermal diffusivity of SGG agrees well with the literature but the thermal diffusivity of Cu is less than the literature value by a factor of ten. The experiment requires further improvement to measure the thermal diffusivity of Cu. However, we succeed in using ethyl alcohol as the coupling medium instead of CCl4 which is highly toxic.

Temporal and spatial distributions of precursory seismicity rate changes in the Thailand-Laos-Myanmar border region: implication for upcoming hazardous earthquakes

Science.gov (United States)

Puangjaktha, Prayot; Pailoplee, Santi

2018-01-01

To study the prospective areas of upcoming strong-to-major earthquakes, i.e., M w ≥ 6.0, a catalog of seismicity in the vicinity of the Thailand-Laos-Myanmar border region was generated and then investigated statistically. Based on the successful investigations of previous works, the seismicity rate change (Z value) technique was applied in this study. According to the completeness earthquake dataset, eight available case studies of strong-to-major earthquakes were investigated retrospectively. After iterative tests of the characteristic parameters concerning the number of earthquakes ( N) and time window ( T w ), the values of 50 and 1.2 years, respectively, were found to reveal an anomalous high Z-value peak (seismic quiescence) prior to the occurrence of six out of the eight major earthquake events studied. In addition, the location of the Z-value anomalies conformed fairly well to the epicenters of those earthquakes. Based on the investigation of correlation coefficient and the stochastic test of the Z values, the parameters used here ( N = 50 events and T w = 1.2 years) were suitable to determine the precursory Z value and not random phenomena. The Z values of this study and the frequency-magnitude distribution b values of a previous work both highlighted the same prospective areas that might generate an upcoming major earthquake: (i) some areas in the northern part of Laos and (ii) the eastern part of Myanmar.

The effect of earth tides as observed in seismo-electromagnetic precursory signals

Directory of Open Access Journals (Sweden)

M. Hayakawa

2009-10-01

Full Text Available Studies on the effect of earth tides in triggering earthquakes (EQs had a great progress in recent years, which has provided convincing evidence of earth tides in EQ triggering. On the other hand, there have been accumulated a lot of evidences on the presence of seismogenic electromagnetic effects (such as ULF electromagnetic emissions from the lithosphere, ionospheric perturbations as detected by subionospheric VLF/LF propagation, etc.. Since the initial agent of these seismogenic electromagnetic effects is obviously due to some mechanical action around the EQ focal zone, the tidal effect as seen in EQ sequence should appear also in seismo-electromagnetic phenomena. Based on this expectation we have studied the tidal effect in different seismogenic phenomena, and have found that lithospheric ULF emissions exhibit a clear maximum-minimum-maximum pattern synchronized with the lunar phase of the EQ during several months before the EQ. As for VLF/LF propagation anomaly representing the lower ionospheric perturbation, we have found the tidal modulation very similar to ULF emissions, but less clear, and also there are some differences from the ULF case (such as occasional shift with respect to the lunar phase and/or the presence of higher frequency modulation, etc.. These findings are indicative that those electromagnetic phenomena reported to be in possible association with an EQ are really related with any preparatory phase of an EQ. This kind of study would be a bridge between the seismology and our seismo-electromagnetic study.

Nociceptive tuning by stem cell factor/c-Kit signaling.

Science.gov (United States)

Milenkovic, Nevena; Frahm, Christina; Gassmann, Max; Griffel, Carola; Erdmann, Bettina; Birchmeier, Carmen; Lewin, Gary R; Garratt, Alistair N

2007-12-06

The molecular mechanisms regulating the sensitivity of sensory circuits to environmental stimuli are poorly understood. We demonstrate here a central role for stem cell factor (SCF) and its receptor, c-Kit, in tuning the responsiveness of sensory neurons to natural stimuli. Mice lacking SCF/c-Kit signaling displayed profound thermal hypoalgesia, attributable to a marked elevation in the thermal threshold and reduction in spiking rate of heat-sensitive nociceptors. Acute activation of c-Kit by its ligand, SCF, resulted in a reduced thermal threshold and potentiation of heat-activated currents in isolated small-diameter neurons and thermal hyperalgesia in mice. SCF-induced thermal hyperalgesia required the TRP family cation channel TRPV1. Lack of c-Kit signaling during development resulted in hypersensitivity of discrete mechanoreceptive neuronal subtypes. Thus, c-Kit can now be grouped with a small family of receptor tyrosine kinases, including c-Ret and TrkA, that control the transduction properties of sensory neurons.

Signal processing in microdosimetry

International Nuclear Information System (INIS)

Arbel, A.

1984-01-01

Signals occurring in microdosimetric measurements cover a dynamic range of 100 dB at a counting rate which normally stays below 10 4 but could increase significantly in case of an accident. The need for high resolution at low energies, non-linear signal processing to accommodate the specified dynamic range, easy calibration and thermal stability are conflicting requirements which pose formidable design problems. These problems are reviewed, and a practical approach to their solution is given employing a single processing channel. (author)

Digital signal processing for a thermal neutron detector using ZnS(Ag):{sup 6}LiF scintillating layers read out with WLS fibers and SiPMs

Energy Technology Data Exchange (ETDEWEB)

Mosset, J.-B., E-mail: jean-baptiste.mosset@psi.ch; Stoykov, A.; Greuter, U.; Hildebrandt, M.; Schlumpf, N.

2016-07-11

We present a digital signal processing system based on a photon counting approach which we developed for a thermal neutron detector consisting of ZnS(Ag):{sup 6}LiF scintillating layers read out with WLS fibers and SiPMs. Three digital filters have been evaluated: a moving sum, a moving sum after differentiation and a digital CR-RC{sup 4} filter. The performances of the detector with these filters are presented. A full analog signal processing using a CR-RC{sup 4} filter has been emulated digitally. The detector performance obtained with this analog approach is compared with the one obtained with the best performing digital approach. - Highlights: • Application of digital signal processing for a SiPM-based ZnS:6LiF neutron detector. • Optimisation of detector performances with 3 different digital filters. • Comparison with detector performances with a full analog signal processing.

Manipulating the Flow of Thermal Noise in Quantum Devices

Science.gov (United States)

Barzanjeh, Shabir; Aquilina, Matteo; Xuereb, André

2018-02-01

There has been significant interest recently in using complex quantum systems to create effective nonreciprocal dynamics. Proposals have been put forward for the realization of artificial magnetic fields for photons and phonons; experimental progress is fast making these proposals a reality. Much work has concentrated on the use of such systems for controlling the flow of signals, e.g., to create isolators or directional amplifiers for optical signals. In this Letter, we build on this work but move in a different direction. We develop the theory of and discuss a potential realization for the controllable flow of thermal noise in quantum systems. We demonstrate theoretically that the unidirectional flow of thermal noise is possible within quantum cascaded systems. Viewing an optomechanical platform as a cascaded system we show here that one can ultimately control the direction of the flow of thermal noise. By appropriately engineering the mechanical resonator, which acts as an artificial reservoir, the flow of thermal noise can be constrained to a desired direction, yielding a thermal rectifier. The proposed quantum thermal noise rectifier could potentially be used to develop devices such as a thermal modulator, a thermal router, and a thermal amplifier for nanoelectronic devices and superconducting circuits.

Photoacoustic signal and noise analysis for Si thin plate: signal correction in frequency domain.

Science.gov (United States)

Markushev, D D; Rabasović, M D; Todorović, D M; Galović, S; Bialkowski, S E

2015-03-01

Methods for photoacoustic signal measurement, rectification, and analysis for 85 μm thin Si samples in the 20-20 000 Hz modulation frequency range are presented. Methods for frequency-dependent amplitude and phase signal rectification in the presence of coherent and incoherent noise as well as distortion due to microphone characteristics are presented. Signal correction is accomplished using inverse system response functions deduced by comparing real to ideal signals for a sample with well-known bulk parameters and dimensions. The system response is a piece-wise construction, each component being due to a particular effect of the measurement system. Heat transfer and elastic effects are modeled using standard Rosencweig-Gersho and elastic-bending theories. Thermal diffusion, thermoelastic, and plasmaelastic signal components are calculated and compared to measurements. The differences between theory and experiment are used to detect and correct signal distortion and to determine detector and sound-card characteristics. Corrected signal analysis is found to faithfully reflect known sample parameters.

Feasibility of Johnson Noise Thermometry based on Digital Signal Processing Techniques

International Nuclear Information System (INIS)

Hwang, In Koo; Kim, Yang Mo

2014-01-01

This paper presents an implementation strategy of noise thermometry based on a digital signal processing technique and demonstrates its feasibilities. A key factor in its development is how to extract the small thermal noise signal from other noises, for example, random noise from amplifiers and continuous electromagnetic interference from the environment. The proposed system consists of two identical amplifiers and uses a cross correlation function to cancel the random noise of the amplifiers. Then, the external interference noises are eliminated by discriminating the difference in the peaks between the thermal signal and external noise. The gain of the amplifiers is estimated by injecting an already known pilot signal. The experimental simulation results of signal processing methods have demonstrated that the proposed approach is an effective method in eliminating an external noise signal and performing gain correction for development of the thermometry

Simultaneous thermal neutron decay time and porosity logging system

International Nuclear Information System (INIS)

Shultz, W.E.

1980-01-01

A method for simultaneously determining the porosity and thermal neutron capture cross-section of earth formations in the vicinity of a well borehole is claimed. It comprises the following steps: passing a well tool into a cased well borehole. The tool has a pulsed source of fast neutrons, a combination fast neutron and gamma ray detector and an epithermal neutron detector; repetitively irradiating the earth formations in the vicinity of the borehole with bursts of fast neutrons; detecting the fast neutron and epithermal neutron populations in the borehole (during the neutron bursts) and generating first and second measurement signals; detecting for second and third time intervals during the time between the neutron bursts, the gamma radiation present in the borehole due to the capture of thermalized neutrons by the nuclei of elements comprising the earth formations and generating third and fourth measurement signals; and combining the first and second measurement signals according to a predetermined relationship to derive an indication of the porosity of the earth formations and combining the third and fourth measurement signals to derive an indication of the thermal neutron capture cross-section of the earth formations

Heat Stress-Induced PI3K/mTORC2-Dependent AKT Signaling Is a Central Mediator of Hepatocellular Carcinoma Survival to Thermal Ablation Induced Heat Stress.

Directory of Open Access Journals (Sweden)

Scott M Thompson

Full Text Available Thermal ablative therapies are important treatment options in the multidisciplinary care of patients with hepatocellular carcinoma (HCC, but lesions larger than 2-3 cm are plagued with high local recurrence rates and overall survival of these patients remains poor. Currently no adjuvant therapies exist to prevent local HCC recurrence in patients undergoing thermal ablation. The molecular mechanisms mediating HCC resistance to thermal ablation induced heat stress and local recurrence remain unclear. Here we demonstrate that the HCC cells with a poor prognostic hepatic stem cell subtype (Subtype HS are more resistant to heat stress than HCC cells with a better prognostic hepatocyte subtype (Subtype HC. Moreover, sublethal heat stress rapidly induces phosphoinositide 3-kinase (PI3K/mammalian target of rapamycin (mTOR dependent-protein kinase B (AKT survival signaling in HCC cells in vitro and at the tumor ablation margin in vivo. Conversely, inhibition of PI3K/mTOR complex 2 (mTORC2-dependent AKT phosphorylation or direct inhibition of AKT function both enhance HCC cell killing and decrease HCC cell survival to sublethal heat stress in both poor and better prognostic HCC subtypes while mTOR complex 1 (mTORC1-inhibition has no impact. Finally, we showed that AKT isoforms 1, 2 and 3 are differentially upregulated in primary human HCCs and that overexpression of AKT correlates with worse tumor biology and pathologic features (AKT3 and prognosis (AKT1. Together these findings define a novel molecular mechanism whereby heat stress induces PI3K/mTORC2-dependent AKT survival signaling in HCC cells and provide a mechanistic rationale for adjuvant AKT inhibition in combination with thermal ablation as a strategy to enhance HCC cell killing and prevent local recurrence, particularly at the ablation margin.

Geomagnetic anomalies - possible earthquake precursors - linked with 2004 significant seismic activity in Vrancea, Romania

International Nuclear Information System (INIS)

Enescu, D.

2005-01-01

The association between a precursory geomagnetic anomaly and a Vrancea earthquake of moderate-to-high magnitude (M W = 6.3) followed by weaker earthquakes (M W W ≤ 6.3 the conclusion of our earlier papers, i.e., that the great majority of Vrancea earthquakes of magnitudes 3.7 ≤ M W ≤5.0 were accompanied by observable precursory electromagnetic anomalies. Our works show that neither the precursor time nor the amplitude of the precursory magnetic anomaly can be linked reliably with the magnitude of the anticipated earthquake. Knowing the way electric resistivity varies ahead of an earthquake, we can assert that the earthquake-precursory growth in geomagnetic impedance is matched by an earthquake-precursory decrease of electric resistivity. (authors)

Study of thermal effects in superconducting RF cavities

International Nuclear Information System (INIS)

Bousson, S.; Caruette, A.; Fouaidy, M.; Hammoudi, N.; Junquera, T.; Lesrel, J.; Yaniche, J.F.

1999-01-01

A high speed thermometric system equipped with 64 fixed surface thermometers is used to investigate thermal effects in several 3 GHz cavities. An evaluation of the time response of our thermometers is presented. A method based on RF signal analysis is proposed to evaluate the normal zone propagation rate during thermal breakdown. (authors)

Study and development of new dosemeters for thermal neutrons; Estudio y desarrollo de nuevos dosimetros para neutrones termicos

Energy Technology Data Exchange (ETDEWEB)

Urena N, F

1998-12-31

An alanine-boron compound, alanine hydroborate, was synthesized and chemically characterized to be used for thermal neutrons fluence measurements. The synthesis of the compound was made by reacting the amino acid alanine with boric acid in three different media: acidic, neutral and alkaline. Physicochemical analysis showed that the alkaline medium is favorable for the synthesis of the alanine hydroborate. The compound was evaluated as a thermal neutron fluence detector by the detection of the free radical yield upon neutron thermal irradiation by Electron Paramagnetic Resonance (EPR). The present work also studies the EPR-signal response of the three preparations to thermal neutron irradiation ({phi} = 5 x 10{sup 7} n/cm{sup 2} -s). The following EPR signal parameters of the samples were investigated: peak-to-peak signal intensity vs. thermal neutron fluence {Phi} = {phi} {Delta}t ; where {Delta}t = 1, 5, 10, 20, 40, 60, 80, 90, 100, 110 and 120 h. , peak-to-peak signal intensity vs. microwave power, signal fading; repeatability, batch homogeneity, stability and zero dose response. It is concluded that these new products could be used in thermal neutron fluence estimations. (Author)

Photoacoustic thermal flowmetry with a single light source

Science.gov (United States)

Liu, Wei; Lan, Bangxin; Hu, Leo; Chen, Ruimin; Zhou, Qifa; Yao, Junjie

2017-09-01

We report a photoacoustic thermal flowmetry based on optical-resolution photoacoustic microscopy (OR-PAM) using a single laser source for both thermal tagging and photoacoustic excitation. When an optically absorbing medium is flowing across the optical focal zone of OR-PAM, a small volume of the medium within the optical focus is repeatedly illuminated and heated by a train of laser pulses with a high repetition rate. The average temperature of the heated volume at each laser pulse is indicated by the photoacoustic signal excited by the same laser pulse due to the well-established linear relationship between the Grueneisen coefficient and the local temperature. The thermal dynamics of the heated medium volume, which are closely related to the flow speed, can therefore be measured from the time course of the detected photoacoustic signals. Here, we have developed a lumped mathematical model to describe the time course of the photoacoustic signals as a function of the medium's flow speed. We conclude that the rising time constant of the photoacoustic signals is linearly dependent on the flow speed. Thus, the flow speed can be quantified by fitting the measured photoacoustic signals using the derived mathematical model. We first performed proof-of-concept experiments using defibrinated bovine blood flowing in a plastic tube. The experiment results have demonstrated that the proposed method has high accuracy (˜±6%) and a wide range of measurable flow speeds. We further validated the method by measuring the blood flow speeds of the microvasculature in a mouse ear in vivo.

An investigation of heat transfer between a microcantilever and a substrate for improved thermal topography imaging

International Nuclear Information System (INIS)

Somnath, Suhas; King, William P

2014-01-01

This paper reports the numerical and experimental investigation of heat transfer from a heated microcantilever to a substrate and uses the resulting insights to improve thermal topography imaging. The cantilever sensitivity, defined as change in thermal signal due to changes in the topography height, is relatively constant for feature heights in the range 100–350 nm. Since the cantilever-substrate heat transfer is governed by thermal conduction through the air, the cantilever sensitivity is nearly constant across substrates of varying thermal conductivity. Surface features with lateral size larger than 2.5 μm can induce artifacts in the cantilever signal resulting in measurement errors as large as 28%. These artifacts arise from thermal conduction from the cantilever in the lateral direction, parallel to the surface. We show how these artifacts can be removed by accounting for this lateral conduction and removing it from the thermal signal. This technique reduces the measurement error by as much as 26%, can be applied to arbitrary substrate topographies, and can be scaled to arrays of heated cantilevers. These results could lead to improvements in nanometer-scale thermal measurements including scanning thermal microscopy and tip-based nanofabrication. (paper)

A magnetotelluric study of the sensitivity of an area to seismoelectric signals

Directory of Open Access Journals (Sweden)

G. Balasis

2005-01-01

Full Text Available During recent years, efforts at better understanding the physical properties of precursory ultra-low frequency pre-seismic electric signals (SES have been intensified. Experiments show that SES cannot be observed at all points of the Earth's surface but only at certain so-called sensitive sites. Moreover, a sensitive site is capable of collecting SES from only a restricted number of seismic areas (selectivity effect. Therefore the installation of a permanent station appropriate for SES collection should necessarily be preceded by a pilot study over a broad area and for a long duration. In short, a number of temporary stations are installed and, after the occurrence of several significant earthquakes (EQs from a given seismic area, the most appropriate (if any of these temporary stations, in the sense that they happen to collect SES, can be selected as permanent. Such a long experiment constitutes a serious disadvantage in identifying a site as SES sensitive. However, the SES sensitivity of a site should be related to the geoelectric structure of the area that hosts the site as well as the regional geoelectric structure between the station and the seismic focal area. Thus, knowledge of the local and regional geoelectric structure can dramatically reduce the time involved in identifying SES sites. In this paper the magnetotelluric method is used to investigate the conductivity structure of an area where a permanent SES station is in operation. Although general conclusions cannot be drawn, the area surrounding an SES site near Ioannina, Greece is characterized by: (1 major faults in the vicinity; (2 highly resistive structure flanked by abrupt conductivity contrasts associated with large-scale geologic contacts, and (3 local inhomogeneities in conductivity structure. The above results are consistent with the fact that electric field amplitudes from remotely-generated signals should be appreciably stronger at such sites when compared to neighboring

Study on infrasonic characteristics of coal samples in failure process under uniaxial loading

Directory of Open Access Journals (Sweden)

Bing Jia

Full Text Available To study the precursory failure infrasonic characteristics of coal samples, coal rock stress loading system and infrasonic wave acquisition system were adopted, and infrasonic tests in uniaxial loading process were made for the coal samples in the studied area. Wavelet filtering, fast Fourier transform, and relative infrasonic energy methods were used to analyze the characteristics of the infrasonic waves in the loading process, including time domain characteristics, and relative energy. The analysis results demonstrated that the frequencies of the infrasonic signals in the loading process mainly distribute within 5–10 Hz, which are significantly different from noise signals. The changes of the infrasonic signals show clear periodic characters in time domain. Meanwhile, the relative energy changes of the infrasonic wave also show periodic characters, which are divided into two stages by the yield limit of coal samples, and are clear and easy to be recognized, so that they can be used as the precursory characteristics for recognizing coal sample failures. Moreover, the infrasonic waves generated by coal samples have low frequency and low attenuation, which can be collected without coupling and transmitted in long distance. This study provides an important support for the further in-situ prediction of coal rock failures. Keywords: Infrasound, Relative energy, Time-frequency analysis, Failure prediction, Identification feature

Thermal degradation of ethanolic biodiesel: Physicochemical and thermal properties evaluation

International Nuclear Information System (INIS)

Silva, Wellington Costa; Castro, Maria Priscila Pessanha; Perez, Victor Haber; Machado, Francisco A.; Mota, Leonardo; Sthel, Marcelo Silva

2016-01-01

The aim of this paper was to study the thermal degradation of soybean biodiesel attained by ethanolic route. The soybean biodiesel samples were subjected to heating treatment at 150 °C for 24 h in a closed oven under controlled atmosphere. During the experiments, samples were withdrawn at intervals of 3, 6, 9, 12, 15 and 24 h for physicochemical and thermophysical properties analysis. The biodiesel degradation was validated by Thermogravimetric analysis since their profiles for control and treated biodiesel were different. Also, "1H NMR confirmed this result due to a significant reduction at the signals related to the "1H located near to the double bonds in the unsaturated ethyl esters in agreement with an iodine index reduction and viscosity increase observed during degradation. Nevertheless, degraded biodiesel, under study conditions, preserved its thermophysical properties. These results may be relevant to qualify the produced biodiesel quality and collect physicochemical and thermophysical data important for applications in combustion studies including project of fuel injection systems. - Highlights: • Soybean biodiesel from ethanolic route was subjected to thermal degradation to verify its stability. • Thermal degradation of biodiesel was correlated with physicochemical properties. • Thermal effusivity, diffusivity and conductivity were estimate by photothermal techniques.

Conditioned pain modulation dampens the thermal grill illusion.

Science.gov (United States)

Harper, D E; Hollins, M

2017-10-01

The thermal grill illusion (TGI) refers to the perception of burning heat and often pain that arises from simultaneous cutaneous application of innocuous warm and cool stimuli. This study utilized conditioned pain modulation (CPM) to help elucidate the TGI's underlying neural mechanisms, including the debated role of ascending nociceptive signals in generating the illusion. To trigger CPM, subjects placed the left hand in noxious cold (6 °C) water before placing the right volar forearm onto a thermal grill. Lower pain and unpleasantness ratings of the grill in this CPM run compared to those in a control run (i.e. 33 °C water) were taken as evidence of CPM. To determine whether CPM reduces noxious heat pain and illusory heat pain equally, an experimental group of subjects rated pain and unpleasantness of a grill consisting of innocuous alternating warm (42 °C) and cool (18 °C) bars, while a control group rated a grill with all bars controlled to a noxious temperature (45 °C). CPM produced significant and comparable reductions in pain, unpleasantness and perceived heat of both noxious heat and the TGI. This result suggests that the TGI results from signals in nociceptive dorsal horn convergent neurons, since CPM involves descending inhibition with high selectivity for this neuronal population. More broadly, CPM's ability to produce a shift in perceived thermal sensation of both noxious heat and the TGI from 'hot' to 'warm' implies that nociceptive signals generated by a cutaneous stimulus can contribute to its perceived thermal intensity. Conditioned pain modulation reduces the perceived painfulness, unpleasantness and heat of the thermal grill illusion and noxious heat similarly. The results have important theoretical implications for both types of pain. © 2017 European Pain Federation - EFIC®.

Sparse estimation of model-based diffuse thermal dust emission

Science.gov (United States)

Irfan, Melis O.; Bobin, Jérôme

2018-03-01

Component separation for the Planck High Frequency Instrument (HFI) data is primarily concerned with the estimation of thermal dust emission, which requires the separation of thermal dust from the cosmic infrared background (CIB). For that purpose, current estimation methods rely on filtering techniques to decouple thermal dust emission from CIB anisotropies, which tend to yield a smooth, low-resolution, estimation of the dust emission. In this paper, we present a new parameter estimation method, premise: Parameter Recovery Exploiting Model Informed Sparse Estimates. This method exploits the sparse nature of thermal dust emission to calculate all-sky maps of thermal dust temperature, spectral index, and optical depth at 353 GHz. premise is evaluated and validated on full-sky simulated data. We find the percentage difference between the premise results and the true values to be 2.8, 5.7, and 7.2 per cent at the 1σ level across the full sky for thermal dust temperature, spectral index, and optical depth at 353 GHz, respectively. A comparison between premise and a GNILC-like method over selected regions of our sky simulation reveals that both methods perform comparably within high signal-to-noise regions. However, outside of the Galactic plane, premise is seen to outperform the GNILC-like method with increasing success as the signal-to-noise ratio worsens.

Kapitza thermal resistance studied by high-frequency photothermal radiometry

International Nuclear Information System (INIS)

Horny, Nicolas; Chirtoc, Mihai; Hamaoui, Georges; Fleming, Austin; Ban, Heng

2016-01-01

Kapitza thermal resistance is determined using high-frequency photothermal radiometry (PTR) extended for modulation up to 10 MHz. Interfaces between 50 nm thick titanium coatings and silicon or stainless steel substrates are studied. In the used configuration, the PTR signal is not sensitive to the thermal conductivity of the film nor to its optical absorption coefficient, thus the Kapitza resistance is directly determined from single thermal parameter fits. Results of thermal resistances show the significant influence of the nature of the substrate, as well as of the presence of free electrons at the interface.

A review of micromachined thermal accelerometers

Science.gov (United States)

Mukherjee, Rahul; Basu, Joydeep; Mandal, Pradip; Guha, Prasanta Kumar

2017-12-01

A thermal convection based micro-electromechanical accelerometer is a relatively new kind of acceleration sensor that does not require a solid proof mass, yielding unique benefits like high shock survival rating, low production cost, and integrability with CMOS integrated circuit technology. This article provides a comprehensive survey of the research, development, and current trends in the field of thermal acceleration sensors, with detailed enumeration on the theory, operation, modeling, and numerical simulation of such devices. Different reported varieties and structures of thermal accelerometers have been reviewed highlighting key design, implementation, and performance aspects. Materials and technologies used for fabrication of such sensors have also been discussed. Further, the advantages and challenges for thermal accelerometers vis-à-vis other prominent accelerometer types have been presented, followed by an overview of associated signal conditioning circuitry and potential applications.

Periodic and stochastic thermal modulation of protein folding kinetics.

Science.gov (United States)

Platkov, Max; Gruebele, Martin

2014-07-21

Chemical reactions are usually observed either by relaxation of a bulk sample after applying a sudden external perturbation, or by intrinsic fluctuations of a few molecules. Here we show that the two ideas can be combined to measure protein folding kinetics, either by periodic thermal modulation, or by creating artificial thermal noise that greatly exceeds natural thermal fluctuations. We study the folding reaction of the enzyme phosphoglycerate kinase driven by periodic temperature waveforms. As the temperature waveform unfolds and refolds the protein, its fluorescence color changes due to FRET (Förster resonant Energy Transfer) of two donor/acceptor fluorophores labeling the protein. We adapt a simple model of periodically driven kinetics that nicely fits the data at all temperatures and driving frequencies: The phase shifts of the periodic donor and acceptor fluorescence signals as a function of driving frequency reveal reaction rates. We also drive the reaction with stochastic temperature waveforms that produce thermal fluctuations much greater than natural fluctuations in the bulk. Such artificial thermal noise allows the recovery of weak underlying signals due to protein folding kinetics. This opens up the possibility for future detection of a stochastic resonance for protein folding subject to noise with controllable amplitude.

Predictability of Landslide Timing From Quasi-Periodic Precursory Earthquakes

Science.gov (United States)

Bell, Andrew F.

2018-02-01

Accelerating rates of geophysical signals are observed before a range of material failure phenomena. They provide insights into the physical processes controlling failure and the basis for failure forecasts. However, examples of accelerating seismicity before landslides are rare, and their behavior and forecasting potential are largely unknown. Here I use a Bayesian methodology to apply a novel gamma point process model to investigate a sequence of quasiperiodic repeating earthquakes preceding a large landslide at Nuugaatsiaq in Greenland in June 2017. The evolution in earthquake rate is best explained by an inverse power law increase with time toward failure, as predicted by material failure theory. However, the commonly accepted power law exponent value of 1.0 is inconsistent with the data. Instead, the mean posterior value of 0.71 indicates a particularly rapid acceleration toward failure and suggests that only relatively short warning times may be possible for similar landslides in future.

Toward automated face detection in thermal and polarimetric thermal imagery

Science.gov (United States)

Gordon, Christopher; Acosta, Mark; Short, Nathan; Hu, Shuowen; Chan, Alex L.

2016-05-01

Visible spectrum face detection algorithms perform pretty reliably under controlled lighting conditions. However, variations in illumination and application of cosmetics can distort the features used by common face detectors, thereby degrade their detection performance. Thermal and polarimetric thermal facial imaging are relatively invariant to illumination and robust to the application of makeup, due to their measurement of emitted radiation instead of reflected light signals. The objective of this work is to evaluate a government off-the-shelf wavelet based naïve-Bayes face detection algorithm and a commercial off-the-shelf Viola-Jones cascade face detection algorithm on face imagery acquired in different spectral bands. New classifiers were trained using the Viola-Jones cascade object detection framework with preprocessed facial imagery. Preprocessing using Difference of Gaussians (DoG) filtering reduces the modality gap between facial signatures across the different spectral bands, thus enabling more correlated histogram of oriented gradients (HOG) features to be extracted from the preprocessed thermal and visible face images. Since the availability of training data is much more limited in the thermal spectrum than in the visible spectrum, it is not feasible to train a robust multi-modal face detector using thermal imagery alone. A large training dataset was constituted with DoG filtered visible and thermal imagery, which was subsequently used to generate a custom trained Viola-Jones detector. A 40% increase in face detection rate was achieved on a testing dataset, as compared to the performance of a pre-trained/baseline face detector. Insights gained in this research are valuable in the development of more robust multi-modal face detectors.

Weld Nugget Temperature Control in Thermal Stir Welding

Science.gov (United States)

Ding, R. Jeffrey (Inventor)

2014-01-01

A control system for a thermal stir welding system is provided. The control system includes a sensor and a controller. The sensor is coupled to the welding system's containment plate assembly and generates signals indicative of temperature of a region adjacent and parallel to the welding system's stir rod. The controller is coupled to the sensor and generates at least one control signal using the sensor signals indicative of temperature. The controller is also coupled to the welding system such that at least one of rotational speed of the stir rod, heat supplied by the welding system's induction heater, and feed speed of the welding system's weld material feeder are controlled based on the control signal(s).

Colour change on different body regions provides thermal and signalling advantages in bearded dragon lizards

Science.gov (United States)

Cadena, Viviana; Porter, Warren P.; Kearney, Michael R.

2016-01-01

Many terrestrial ectotherms are capable of rapid colour change, yet it is unclear how these animals accommodate the multiple functions of colour, particularly camouflage, communication and thermoregulation, especially when functions require very different colours. Thermal benefits of colour change depend on an animal's absorptance of solar energy in both UV–visible (300–700 nm) and near-infrared (NIR; 700–2600 nm) wavelengths, yet colour research has focused almost exclusively on the former. Here, we show that wild-caught bearded dragon lizards (Pogona vitticeps) exhibit substantial UV–visible and NIR skin reflectance change in response to temperature for dorsal but not ventral (throat and upper chest) body regions. By contrast, lizards showed the greatest temperature-independent colour change on the beard and upper chest during social interactions and as a result of circadian colour change. Biophysical simulations of heat transfer predicted that the maximum temperature-dependent change in dorsal reflectivity could reduce the time taken to reach active body temperature by an average of 22 min per active day, saving 85 h of basking time throughout the activity season. Our results confirm that colour change may serve a thermoregulatory function, and competing thermoregulation and signalling requirements may be met by partitioning colour change to different body regions in different circumstances.

Characterization of thermal aging of duplex stainless steel by SQUID

International Nuclear Information System (INIS)

Isobe, Y.; Kamimura, A.; Aoki, K.; Nakayasu, F.

1995-01-01

Thermal aging is a growing concern for long-term-aged duplex stainless steel piping in nuclear power plants. Superconducting QUantum Interference Device (SQUID) was used for the detection of thermal aging of SUS329 rolled duplex stainless steel and SCS16 cast duplex stainless steel. It was found that the SQUID output signal pattern in the presence of AC magnetic field applied to the specimen was sensitive to the changes in electromagnetic properties due to thermal aging

Thermal Characterization of Edible Oils by Using Photopyroelectric Technique

Science.gov (United States)

Lara-Hernández, G.; Suaste-Gómez, E.; Cruz-Orea, A.; Mendoza-Alvarez, J. G.; Sánchez-Sinéncio, F.; Valcárcel, J. P.; García-Quiroz, A.

2013-05-01

Thermal properties of several edible oils such as olive, sesame, and grape seed oils were obtained by using the photopyroelectric technique. The inverse photopyroelectric configuration was used in order to obtain the thermal effusivity of the oil samples. The theoretical equation for the photopyroelectric signal in this configuration, as a function of the incident light modulation frequency, was fitted to the experimental data in order to obtain the thermal effusivity of these samples. Also, the back photopyroelectric configuration was used to obtain the thermal diffusivity of these oils; this thermal parameter was obtained by fitting the theoretical equation for this configuration, as a function of the sample thickness (called the thermal wave resonator cavity), to the experimental data. All measurements were done at room temperature. A complete thermal characterization of these edible oils was achieved by the relationship between the obtained thermal diffusivities and thermal effusivities with their thermal conductivities and volumetric heat capacities. The obtained results are in agreement with the thermal properties reported for the case of the olive oil.

Properties of the geoelectric structure that promote the detection of electrotelluric anomalies. The case of Ioannina, Greece

Energy Technology Data Exchange (ETDEWEB)

Makris, J. P. [Technological Educational Institute of Crete, Dept. of Electronics (Branch of Chania), Chalepa, Chania, Crete (Greece)

2001-04-01

The reliable detection and identification of electrotelluric anomalies that could be considered as precursory phenomena of earthquakes become fundamental aspects of earthquake prediction research. Special arrangements, in local and/or regional scale, of the geoelectric structure beneath the measuring point, may act as natural realtime filters on the ULF electrotelluric data improving considerably the signal to magnetotelluric-noise ratio of anomalies originated by probably non-magnetotelluric sources. Linear polarization, i.e. local channelling of the electric field on the surface is expected in cases where 3D-local inhomogeneities, producing strong shear distortion, are present in the vicinity of the monitoring site and/or when a 2D-regional geoelectrical setting exhibits high anisotropy. By assuming different generation mechanisms and modes of propagation for the electrotelluric anomalies that could be considered earthquake precursory phenomena, a rotationally originated residual electrotelluric field results, eliminating background magnetotelluric-noise and revealing hidden transient variations that could be associated to earthquakes. The suggested method is applicable in real-time data collection, thus simplifies and accelerates the tedious task of identification of suspicious signals. As an indicative example, the case of Ioannina (located in Northwestern Greece) is presented. The local polarization of the electrotelluric field varies dramatically even at neighboring points although the regional geoelectric strike direction does not change.

Change detection and characterization of volcanic activity using ground based low-light and near infrared cameras to monitor incandescence and thermal signatures

Science.gov (United States)

Harrild, Martin; Webley, Peter; Dehn, Jonathan

2015-04-01

Knowledge and understanding of precursory events and thermal signatures are vital for monitoring volcanogenic processes, as activity can often range from low level lava effusion to large explosive eruptions, easily capable of ejecting ash up to aircraft cruise altitudes. Using ground based remote sensing techniques to monitor and detect this activity is essential, but often the required equipment and maintenance is expensive. Our investigation explores the use of low-light cameras to image volcanic activity in the visible to near infrared (NIR) portion of the electromagnetic spectrum. These cameras are ideal for monitoring as they are cheap, consume little power, are easily replaced and can provide near real-time data. We focus here on the early detection of volcanic activity, using automated scripts, that capture streaming online webcam imagery and evaluate image pixel brightness values to determine relative changes and flag increases in activity. The script is written in Python, an open source programming language, to reduce the overall cost to potential consumers and increase the application of these tools across the volcanological community. In addition, by performing laboratory tests to determine the spectral response of these cameras, a direct comparison of collocated low-light and thermal infrared cameras has allowed approximate eruption temperatures and effusion rates to be determined from pixel brightness. The results of a field campaign in June, 2013 to Stromboli volcano, Italy, are also presented here. Future field campaigns to Latin America will include collaborations with INSIVUMEH in Guatemala, to apply our techniques to Fuego and Santiaguito volcanoes.

Leptin Signaling Is Required for Adaptive Changes in Food Intake, but Not Energy Expenditure, in Response to Different Thermal Conditions

Science.gov (United States)

Kaiyala, Karl J.; Ogimoto, Kayoko; Nelson, Jarrell T.; Schwartz, Michael W.; Morton, Gregory J.

2015-01-01

Survival of free-living animals depends on the ability to maintain core body temperature in the face of rapid and dramatic changes in their thermal environment. If food intake is not adjusted to meet the changing energy demands associated with changes of ambient temperature, a serious challenge to body energy stores can occur. To more fully understand the coupling of thermoregulation to energy homeostasis in normal animals and to investigate the role of the adipose hormone leptin to this process, comprehensive measures of energy homeostasis and core temperature were obtained in leptin-deficient ob/ob mice and their wild-type (WT) littermate controls when housed under cool (14°C), usual (22°C) or ∼ thermoneutral (30°C) conditions. Our findings extend previous evidence that WT mice robustly defend normothermia in response to either a lowering (14°C) or an increase (30°C) of ambient temperature without changes in body weight or body composition. In contrast, leptin-deficient, ob/ob mice fail to defend normothermia at ambient temperatures lower than thermoneutrality and exhibit marked losses of both body fat and lean mass when exposed to cooler environments (14°C). Our findings further demonstrate a strong inverse relationship between ambient temperature and energy expenditure in WT mice, a relationship that is preserved in ob/ob mice. However, thermal conductance analysis indicates defective heat retention in ob/ob mice, irrespective of temperature. While a negative relationship between ambient temperature and energy intake also exists in WT mice, this relationship is disrupted in ob/ob mice. Thus, to meet the thermoregulatory demands of different ambient temperatures, leptin signaling is required for adaptive changes in both energy intake and thermal conductance. A better understanding of the mechanisms coupling thermoregulation to energy homeostasis may lead to the development of new approaches for the treatment of obesity. PMID:25756181

A new solution of measuring thermal response of prestressed concrete bridge girders for structural health monitoring

International Nuclear Information System (INIS)

Jiao, Pengcheng; Borchani, Wassim; Hasni, Hassene; Lajnef, Nizar

2017-01-01

This study develops a novel buckling-based mechanism to measure the thermal response of prestressed concrete bridge girders under continuous temperature changes for structural health monitoring. The measuring device consists of a bilaterally constrained beam and a piezoelectric polyvinylidene fluoride transducer that is attached to the beam. Under thermally induced displacement, the slender beam is buckled. The post-buckling events are deployed to convert the low-rate and low-frequency excitations into localized high-rate motions and, therefore, the attached piezoelectric transducer is triggered to generate electrical signals. Attaching the measuring device to concrete bridge girders, the electrical signals are used to detect the thermal response of concrete bridges. Finite element simulations are conducted to obtain the displacement of prestressed concrete girders under thermal loads. Using the thermal-induced displacement as input, experiments are carried out on a 3D printed measuring device to investigate the buckling response and corresponding electrical signals. A theoretical model is developed based on the nonlinear Euler–Bernoulli beam theory and large deformation assumptions to predict the buckling mode transitions of the beam. Based on the presented theoretical model, the geometry properties of the measuring device can be designed such that its buckling response is effectively controlled. Consequently, the thermally induced displacement can be designed as limit states to detect excessive thermal loads on concrete bridge girders. The proposed solution sufficiently measures the thermal response of concrete bridges. (paper)

A new solution of measuring thermal response of prestressed concrete bridge girders for structural health monitoring

Science.gov (United States)

Jiao, Pengcheng; Borchani, Wassim; Hasni, Hassene; Lajnef, Nizar

2017-08-01

This study develops a novel buckling-based mechanism to measure the thermal response of prestressed concrete bridge girders under continuous temperature changes for structural health monitoring. The measuring device consists of a bilaterally constrained beam and a piezoelectric polyvinylidene fluoride transducer that is attached to the beam. Under thermally induced displacement, the slender beam is buckled. The post-buckling events are deployed to convert the low-rate and low-frequency excitations into localized high-rate motions and, therefore, the attached piezoelectric transducer is triggered to generate electrical signals. Attaching the measuring device to concrete bridge girders, the electrical signals are used to detect the thermal response of concrete bridges. Finite element simulations are conducted to obtain the displacement of prestressed concrete girders under thermal loads. Using the thermal-induced displacement as input, experiments are carried out on a 3D printed measuring device to investigate the buckling response and corresponding electrical signals. A theoretical model is developed based on the nonlinear Euler-Bernoulli beam theory and large deformation assumptions to predict the buckling mode transitions of the beam. Based on the presented theoretical model, the geometry properties of the measuring device can be designed such that its buckling response is effectively controlled. Consequently, the thermally induced displacement can be designed as limit states to detect excessive thermal loads on concrete bridge girders. The proposed solution sufficiently measures the thermal response of concrete bridges.

Superimpose methods for uncooled infrared camera applied to the micro-scale thermal characterization of composite materials

Science.gov (United States)

Morikawa, Junko

2015-05-01

The mobile type apparatus for a quantitative micro-scale thermography using a micro-bolometer was developed based on our original techniques such as an achromatic lens design to capture a micro-scale image in long-wave infrared, a video signal superimposing for the real time emissivity correction, and a pseudo acceleration of a timeframe. The total size of the instrument was designed as it was put in the 17 cm x 28 cm x 26 cm size carrying box. The video signal synthesizer enabled to record a direct digital signal of monitoring temperature or positioning data. The encoded digital signal data embedded in each image was decoded to read out. The protocol to encode/decode the measured data was originally defined. The mixed signals of IR camera and the imposed data were applied to the pixel by pixel emissivity corrections and the pseudo-acceleration of the periodical thermal phenomena. Because the emissivity of industrial materials and biological tissues were usually inhomogeneous, it has the different temperature dependence on each pixel. The time-scale resolution for the periodic thermal event was improved with the algorithm for "pseudoacceleration". It contributes to reduce the noise by integrating the multiple image data, keeping a time resolution. The anisotropic thermal properties of some composite materials such as thermal insulating materials of cellular plastics and the biometric composite materials were analyzed using these techniques.

Unusually deep Bonin earthquake of 30 May 2015: A precursory signal to slab penetration?

Science.gov (United States)

Obayashi, Masayuki; Fukao, Yoshio; Yoshimitsu, Junko

2017-02-01

An M7.9 earthquake occurred on 30 May 2015 at an unusual depth of 680 km downward and away from the well-defined Wadati-Benioff (WB) zone of the southern Bonin arc. To the north (northern Bonin), the subducted slab is stagnant above the upper-lower mantle boundary at 660-km depth, where the WB zone bends forward to sub-horizontal. To the south (northern Mariana), it penetrates the boundary, where the WB zone extends near-vertically down to the boundary. Thus, the southern Bonin slab can be regarded as being in a transitional state from slab stagnation to penetration. The transition is shown to happen rapidly within the northern half of the southern Bonin slab where the heel part of the shoe-like configured stagnant slab hits the significantly depressed 660-km discontinuity. The mainshock and aftershocks took place in this heel part where they are sub-vertically aligned in approximate parallel to their maximum compressional axes. Here, the dips of the compressional axes of WB zone earthquakes change rapidly across the thickness of the slab from the eastern to western side and along the strike of the slab from the northern to southern side, suggesting rapid switching of the downdip compression axis in the shoe-shaped slab. Elastic deformation associated with the WB zone seismicity is calculated by viewing it as an integral part of the slab deformation process. With this deformation, the heel part is deepened relative to the arch part and is compressed sub-vertically and stretched sub-horizontally, a tendency consistent with the idea of progressive decent of the heel part in which near-vertical compressional stress is progressively accumulated to generate isolated shocks like the 2015 event and eventually to initiate slab penetration.

Thermal gradients caused by the CANDU moderator circulation

International Nuclear Information System (INIS)

Mohindra, V.K.; Vartolomei, M.A.; Scharfenberg, R.

2008-01-01

The heavy water moderator circulation system of a CANDU reactor, maintains calandria moderator temperature at power-dependent design values. The temperature differentials between the moderator and the cooler heavy water entering the calandria generate thermal gradients in the reflector and moderator. The resultant small changes in thermal neutron population are detected by the out-of-core ion chambers as small, continuous fluctuations of the Log Rate signals. The impact of the thermal gradients on the frequency of the High Log Rate fluctuations and their amplitude is relatively more pronounced for Bruce A as compared to Bruce B reactors. The root cause of the Log Rate fluctuations was investigated using Bruce Power operating plant information data and the results of the investigation support the interpretation based on the thermal gradient phenomenon. (author)

Three-dimensional illusion thermal device for location camouflage.

Science.gov (United States)

Wang, Jing; Bi, Yanqiang; Hou, Quanwen

2017-08-08

Thermal metamaterials, proposed in recent years, provide a new method to manipulate the energy flux in heat transfer, and result in many novel thermal devices. In this paper, an illusion thermal device for location camouflage in 3-dimensional heat conduction regime is proposed based on the transformation thermodynamics. The heat source covered by the device produces a fake signal outside the device, which makes the source look like appearing at another position away from its real position. The parameters required by the device are deduced and the method is validated by simulations. The possible scheme to obtain the thermal conductivities required in the device by composing natural materials is supplied, and the influence of some problems in practical fabrication process of the device on the effect of the camouflage is also discussed.

Gene Expression Dynamics Accompanying the Sponge Thermal Stress Response.

Science.gov (United States)

Guzman, Christine; Conaco, Cecilia

2016-01-01

Marine sponges are important members of coral reef ecosystems. Thus, their responses to changes in ocean chemistry and environmental conditions, particularly to higher seawater temperatures, will have potential impacts on the future of these reefs. To better understand the sponge thermal stress response, we investigated gene expression dynamics in the shallow water sponge, Haliclona tubifera (order Haplosclerida, class Demospongiae), subjected to elevated temperature. Using high-throughput transcriptome sequencing, we show that these conditions result in the activation of various processes that interact to maintain cellular homeostasis. Short-term thermal stress resulted in the induction of heat shock proteins, antioxidants, and genes involved in signal transduction and innate immunity pathways. Prolonged exposure to thermal stress affected the expression of genes involved in cellular damage repair, apoptosis, signaling and transcription. Interestingly, exposure to sublethal temperatures may improve the ability of the sponge to mitigate cellular damage under more extreme stress conditions. These insights into the potential mechanisms of adaptation and resilience of sponges contribute to a better understanding of sponge conservation status and the prediction of ecosystem trajectories under future climate conditions.

Fuel rod quenching with oxidation and precursory cooling

International Nuclear Information System (INIS)

Davidi, A.; Elias, E.; Olek, S.

1999-01-01

During a loss-of-coolant-accident in LWR fuel rods may be temporarily exposed thus reaching high temperature levels. The injection of cold water into the core, while providing the necessary cooling to prevent melting may also generate steam inducing exothermal oxidation of the cladding. A number of high temperature quenching experiments [I] have demonstrated that during the early phase of the quenching process, the rate of hydrogen generation increased markedly and the surface temperatures rose rapidly. These effects are believed to result from thermal stresses breaking up the oxide layer on the zircalloy cladding, thus exposing the inner surface to oxidizing atmosphere. Steam reacts exothermally with the metallic components of the newly formed surface causing temporarily local temperature escalation. The main objective of this study is to develop and assess a one-dimensional time-dependent rewetting model to address the problem of quenching of hot surfaces undergoing exothermic oxidation reactions. Addressing a time-dependent problem is an important aspect of the work since it is believed that the progression of a quench-front along a hot oxidizing surface is an unsteady process. Several studies dealing with time-dependent rewetting problems have been published, e.g. [2]-[5], but none considers oxidation reactions downstream of the quench-front. The main difficulty in solving time-dependent rewetting problems stems from the fact that either the quench-front velocity or the quench-front positions constitute a time-dependent eigenvalue of the problem. The model is applied to describe the interrelated processes of cooling and exothermic steam-metal reactions at the vapor zirconium-cladding interface during quenching of degraded fuel rods. A constant heat transfer coefficient is assumed upstream of the quenching front whereas the combined effect of oxidation and post dry-out cooling is described by prescribing a heat flux distribution of general form downstream. The

More on the TR-OSL signal from BeO ceramics

International Nuclear Information System (INIS)

Bulur, Enver

2014-01-01

Time Resolved Optically Stimulated Luminescence (TR-OSL) from BeO ceramics was investigated using blue (445 nm) and near-IR light (852 nm) for stimulation. Stimulation spectrum of the TR-OSL signal – as measured in the interval 700 to 420 nm- was observed to increase monotonically with the decreasing stimulation wavelength. In addition to the “fast” and “slow” components observed with blue light stimulation, IR stimulated TR-OSL spectra of irradiated BeO ceramics were observed to have two components with average lifetimes around ∼2.5 μs and ∼17 μs. Emission spectra of the both IR stimulated TR-OSL components were observed to have a broad emission band peaking around 330 nm. Thermal stability of the IR stimulated TR-OSL signal was studied by making preheating experiments in the range from 100 °C to 190 °C. It was observed that the IR stimulated OSL signal is stable up to ∼150 °C and decay afterwards. Radiation dose response of the IR stimulated luminescence signal was obtained in the range from 5 to 500 Gy. Both blue and IR stimulated TR-OSL signals grew up to 100 Gy and exhibited saturation for higher doses. Additionally, measurement temperature dependence of the components was also investigated and for the ∼2 μs component thermal assistance with activation energy around 0.16 eV was observed. It seems that the fast component of the blue stimulated TR-OSL component can be correlated to the ∼2 μs IR stimulated TR-OSL component. - Highlights: • IR Stimulated Time-Resolved OSL from BeO was studied. • Two components with lifetimes ∼2 and ∼17us were observed. • IR stimulated TR-OSL signal is found to be stable up to 150 °C. • Thermal quenching energy of the 2us component was found as 0.16 eV

Progress in thermal comfort research over the last twenty years

DEFF Research Database (Denmark)

Dear, R. J. de; Akimoto, T.; Arens, E. A.

2013-01-01

Climate change and the urgency of decarbonizing the built environment are driving technological innovation in the way we deliver thermal comfort to occupants. These changes, in turn, seem to be setting the directions for contemporary thermal comfort research. This article presents a literature...... review of major changes, developments, and trends in the field of thermal comfort research over the last 20 years. One of the main paradigm shift was the fundamental conceptual reorientation that has taken place in thermal comfort thinking over the last 20 years; a shift away from the physically based...... developed, driven by the continuous challenge to model thermal comfort at the same anatomical resolution and to combine these localized signals into a coherent, global thermal perception. Finally, the demand for ever increasing building energy efficiency is pushing technological innovation in the way we...

Laser induced purely-thermal-wave interferometry (PTWI) using a novel photopyroelectric (PPE) instrument

Science.gov (United States)

Wang, Chinhua

A novel purely thermal-wave interferometric technique and its applications to non-contact and non-destructive evaluation of Ti:sapphire laser crystals, high-precision measurement of thermal diffusivity of gases, and high- sensitivity gas (hydrogen) sensors have been successfully developed both theoretically and experimentally. A comprehensive theoretical and experimental analysis of the system noise and detectivity has been conducted to consolidate the basis of the technique. Unlike the conventional single-ended photopyroelectric(PPE) technique, different thermal-wave interference patterns can be obtained by adjusting two incident beams (relative intensity and phase shift) and two thermal-wave cavities on both sides of a pyroelectric detector. It is found that the large base-line signal and large optical noise, which are encountered in the single- ended PPE scheme, can be coherently and completely suppressed in the fully destructive interferometric measurement. Differential surface absorptance, differential and absolute bulk absorption coefficient of Ti:sapphire laser crystals have been separately measured using an extended PPE-interference (PPEI) theory. Unlike the single-ended PPE method, in which thermal contributions from several optical parameters are always coupled together, the destructive interferometric: method provides a unique method for extracting precise values of one of these coupled parameters, without the need of equally precise knowledge of the values of others. The comparison measurement of thermal diffusivity of air using the single-ended PPE method and the PPEI method shows that the PPEI method enhances the measuring precision by one significant figure when compared with the single-beam method. The conventionally used concept of ``thermal-wave reflection coefficient'' has been extended to a more general case that is sample- thickness dependent. A novel hydrogen gas sensor has been initialized and developed based on the PPEI technique. It is

Reactor Antineutrinos Signal all over the world

OpenAIRE

Ricci, B.; Mantovani, F.; Baldoncini, M.; Esposito, J.; Ludhova, L.; Zavatarelli, S.

2014-01-01

We present an updated estimate of reactor antineutrino signal all over the world, with particular attention to the sites proposed for existing and future geo-neutrino experiment. In our calculation we take into account the most updated data on Thermal Power for each nuclear plant, on reactor antineutrino spectra and on three neutrino oscillation mechanism.

Automatic Thermal Control System with Temperature Difference or Derivation Feedback

Directory of Open Access Journals (Sweden)

Darina Matiskova

2016-02-01

Full Text Available Automatic thermal control systems seem to be non-linear systems with thermal inertias and time delay. A controller is also non-linear because its information and power signals are limited. The application of methods that are available to on-linear systems together with computer simulation and mathematical modelling creates a possibility to acquire important information about the researched system. This paper provides a new look at the heated system model and also designs the structure of the thermal system with temperature derivation feedback. The designed system was simulated by using a special software in Turbo Pascal. Time responses of this system are compared to responses of a conventional thermal system. The thermal system with temperature derivation feedback provides better transients, better quality of regulation and better dynamical properties.

Discrimination techniques employing both reflective and thermal multispectral signals. [for remote sensor technology

Science.gov (United States)

Malila, W. A.; Crane, R. B.; Richardson, W.

1973-01-01

Recent improvements in remote sensor technology carry implications for data processing. Multispectral line scanners now exist that can collect data simultaneously and in registration in multiple channels at both reflective and thermal (emissive) wavelengths. Progress in dealing with two resultant recognition processing problems is discussed: (1) More channels mean higher processing costs; to combat these costs, a new and faster procedure for selecting subsets of channels has been developed. (2) Differences between thermal and reflective characteristics influence recognition processing; to illustrate the magnitude of these differences, some explanatory calculations are presented. Also introduced, is a different way to process multispectral scanner data, namely, radiation balance mapping and related procedures. Techniques and potentials are discussed and examples presented.

Organic and inorganic decomposition products from the thermal desorption of atmospheric particles

Science.gov (United States)

Williams, Brent J.; Zhang, Yaping; Zuo, Xiaochen; Martinez, Raul E.; Walker, Michael J.; Kreisberg, Nathan M.; Goldstein, Allen H.; Docherty, Kenneth S.; Jimenez, Jose L.

2016-04-01

Atmospheric aerosol composition is often analyzed using thermal desorption techniques to evaporate samples and deliver organic or inorganic molecules to various designs of detectors for identification and quantification. The organic aerosol (OA) fraction is composed of thousands of individual compounds, some with nitrogen- and sulfur-containing functionality and, often contains oligomeric material, much of which may be susceptible to decomposition upon heating. Here we analyze thermal decomposition products as measured by a thermal desorption aerosol gas chromatograph (TAG) capable of separating thermal decomposition products from thermally stable molecules. The TAG impacts particles onto a collection and thermal desorption (CTD) cell, and upon completion of sample collection, heats and transfers the sample in a helium flow up to 310 °C. Desorbed molecules are refocused at the head of a gas chromatography column that is held at 45 °C and any volatile decomposition products pass directly through the column and into an electron impact quadrupole mass spectrometer. Analysis of the sample introduction (thermal decomposition) period reveals contributions of NO+ (m/z 30), NO2+ (m/z 46), SO+ (m/z 48), and SO2+ (m/z 64), derived from either inorganic or organic particle-phase nitrate and sulfate. CO2+ (m/z 44) makes up a major component of the decomposition signal, along with smaller contributions from other organic components that vary with the type of aerosol contributing to the signal (e.g., m/z 53, 82 observed here for isoprene-derived secondary OA). All of these ions are important for ambient aerosol analyzed with the aerosol mass spectrometer (AMS), suggesting similarity of the thermal desorption processes in both instruments. Ambient observations of these decomposition products compared to organic, nitrate, and sulfate mass concentrations measured by an AMS reveal good correlation, with improved correlations for OA when compared to the AMS oxygenated OA (OOA

Deformation regime and long-term precursors to eruption at large calderas: Rabaul, Papua New Guinea

Science.gov (United States)

Robertson, Robert M.; Kilburn, Christopher R. J.

2016-03-01

Eruptions at large calderas are normally preceded by variable rates of unrest that continue for decades or more. A classic example is the 1994 eruption of Rabaul caldera, in Papua New Guinea, which began after 23 years of surface uplift and volcano-tectonic (VT) seismicity at rates that changed unevenly with time by an order of magnitude. Although the VT event rate and uplift rate peaked in 1983-1985, eruptions only began a decade later and followed just 27 hours of anomalous changes in precursory signal. Here we argue that the entire 23 years of unrest belongs to a single sequence of damage accumulation in the crust and that, in 1991-1992, the crust's response to applied stress changed from quasi-elastic (elastic deformation with minor fault movement) to inelastic (deformation predominantly by fault movement alone). The change in behaviour yields limiting trends in the variation of VT event rate with deformation and can be quantified with a mean-field model for an elastic crust that contains a dispersed population of small faults. The results show that identifying the deformation regime for elastic-brittle crust provides new criteria for using precursory time series to evaluate the potential for eruption. They suggest that, in the quasi-elastic regime, short-term increases in rates of deformation and VT events are unreliable indicators of an imminent eruption, but that, in the inelastic regime, the precursory rates may follow hyperbolic increases with time and offer the promise of developing forecasts of eruption as much as months beforehand.

Reduction of thermal quenching of biotite mineral due to annealing

International Nuclear Information System (INIS)

Kalita, J.M.; Wary, G.

2014-01-01

Graphical abstract: - Highlights: • Thermoluminescence of X-ray irradiate biotite was studied at various heating rates. • Thermal quenching was found to decrease with increase in annealing temperature. • Due to annealing one trap level was vanished and a new shallow trap level generated. • The new trap level contributes low thermally quenched thermoluminescence signal. - Abstract: Thermoluminescence (TL) of X-ray irradiated natural biotite annealed at 473, 573, 673 and 773 K were studied within 290–480 K at various linear heating rates (2, 4, 6, 8 and 10 K/s). A Computerized Glow Curve Deconvolution technique was used to study various TL parameters. Thermal quenching was found to be very high for un-annealed sample, however it decreased significantly with increase in annealing temperature. For un-annealed sample thermal quenching activation energy (W) and pre-exponential frequency factor (C) were found to be W = (2.71 ± 0.05) eV and C = (2.38 ± 0.05) × 10 12 s −1 respectively. However for 773 K annealed sample, these parameters were found to be W = (0.63 ± 0.03) eV, C = (1.75 ± 0.27) × 10 14 s −1 . Due to annealing, the initially present trap level at depth 1.04 eV was vanished and a new shallow trap state was generated at depth of 0.78 eV which contributes very low thermally quenched TL signal

Thermal conductivity profile determination in proton-irradiated ZrC by spatial and frequency scanning thermal wave methods

International Nuclear Information System (INIS)

Jensen, C.; Chirtoc, M.; Horny, N.; Antoniow, J. S.; Pron, H.; Ban, H.

2013-01-01

Using complementary thermal wave methods, the irradiation damaged region of zirconium carbide (ZrC) is characterized by quantifiably profiling the thermophysical property degradation. The ZrC sample was irradiated by a 2.6 MeV proton beam at 600 °C to a dose of 1.75 displacements per atom. Spatial scanning techniques including scanning thermal microscopy (SThM), lock-in infrared thermography (lock-in IRT), and photothermal radiometry (PTR) were used to directly map the in-depth profile of thermal conductivity on a cross section of the ZrC sample. The advantages and limitations of each system are discussed and compared, finding consistent results from all techniques. SThM provides the best resolution finding a very uniform thermal conductivity envelope in the damaged region measuring ∼52 ± 2 μm deep. Frequency-based scanning PTR provides quantification of the thermal parameters of the sample using the SThM measured profile to provide validation of a heating model. Measured irradiated and virgin thermal conductivities are found to be 11.9 ± 0.5 W m −1 K −1 and 26.7 ±1 W m −1 K −1 , respectively. A thermal resistance evidenced in the frequency spectra of the PTR results was calculated to be (1.58 ± 0.1) × 10 −6 m 2 K W −1 . The measured thermal conductivity values compare well with the thermal conductivity extracted from the SThM calibrated signal and the spatially scanned PTR. Combined spatial and frequency scanning techniques are shown to provide a valuable, complementary combination for thermal property characterization of proton-irradiated ZrC. Such methodology could be useful for other studies of ion-irradiated materials

Simplified methods to assess thermal fatigue due to turbulent mixing

International Nuclear Information System (INIS)

Hannink, M.H.C.; Timperi, A.

2011-01-01

Thermal fatigue is a safety relevant damage mechanism in pipework of nuclear power plants. A well-known simplified method for the assessment of thermal fatigue due to turbulent mixing is the so-called sinusoidal method. Temperature fluctuations in the fluid are described by a sinusoidally varying signal at the inner wall of the pipe. Because of limited information on the thermal loading conditions, this approach generally leads to overconservative results. In this paper, a new assessment method is presented, which has the potential of reducing the overconservatism of existing procedures. Artificial fluid temperature signals are generated by superposition of harmonic components with different amplitudes and frequencies. The amplitude-frequency spectrum of the components is modelled by a formula obtained from turbulence theory, whereas the phase differences are assumed to be randomly distributed. Lifetime predictions generated with the new simplified method are compared with lifetime predictions based on real fluid temperature signals, measured in an experimental setup of a mixing tee. Also, preliminary steady-state Computational Fluid Dynamics (CFD) calculations of the total power of the fluctuations are presented. The total power is needed as an input parameter for the spectrum formula in a real-life application. Solution of the transport equation for the total power was included in a CFD code and comparisons with experiments were made. The newly developed simplified method for generating the temperature signal is shown to be adequate for the investigated geometry and flow conditions, and demonstrates possibilities of reducing the conservatism of the sinusoidal method. CFD calculations of the total power show promising results, but further work is needed to develop the approach. (author)

Mechanical properties and eddy current testing of thermally aged Z3CN20.09M cast duplex stainless steel

Science.gov (United States)

Liu, Tonghua; Wang, Wei; Qiang, Wenjiang; Shu, Guogang

2018-04-01

To study the thermal aging embrittlement of Z3CN20.09M duplex stainless steel produced in China, accelerated thermal aging experiments were carried out at 380 °C up to 9000 h. Microhardness measurements, Charpy impact and eddy current tests were performed on aged samples to characterize their thermal aging embrittlement. The results showed that the signal amplitude of eddy current decreased with the increase in aging time. Two quantitative correlations of the eddy current signal amplitude with both the Charpy impact energy, and the Vickers microhardness of the ferrite phase are obtained. The study showed that eddy current testing could be used to non-destructively evaluate the thermal aging embrittlement of cast duplex stainless steels.

Non-invasive thermal profiling of silicon wafer surface during RTP using acoustic and signal processing techniques

Science.gov (United States)

Syed, Ahmed Rashid

Among the great physical challenges faced by the current front-end semiconductor equipment manufacturers is the accurate and repeatable surface temperature measurement of wafers during various fabrication steps. Close monitoring of temperature is essential in that it ensures desirable device characteristics to be reliably reproduced across various wafer lots. No where is the need to control temperature more pronounced than it is during Rapid Thermal Processing (RTP) which involves temperature ramp rates in excess of 200°C/s. This dissertation presents an elegant and practical approach to solve the wafer surface temperature estimation problem, in context of RTP, by deploying hardware that acquires the necessary data while preserving the integrity and purity of the wafer. In contrast to the widely used wafer-contacting (and hence contaminating) methods, such as bonded thermocouples, or environment sensitive schemes, such as light-pipes and infrared pyrometry, the proposed research explores the concept of utilizing Lamb (acoustic) waves to detect changes in wafer surface temperature, during RTP. Acoustic waves are transmitted to the wafer via an array of quartz rods that normally props the wafer inside an RTP chamber. These waves are generated using piezoelectric transducers affixed to the bases of the quartz rods. The group velocity of Lamb waves traversing the wafer surface undergoes a monotonic decrease with rise in wafer temperature. The correspondence of delay in phase of the received Lamb waves and the ambient temperature, along all direct paths between sending and receiving transducers, yields a psuedo real-time thermal image of the wafer. Although the custom built hardware-setup implements the above "proof-of-concept" scheme by transceiving acoustic signals at a single frequency, the real-world application will seek to enhance the data acquistion. rate (>1000 temperature measurements per seconds) by sending and receiving Lamb waves at multiple frequencies (by

Self-organised critical features in soil radon and MHz electromagnetic disturbances: Results from environmental monitoring in Greece

International Nuclear Information System (INIS)

Petraki, Ermioni; Nikolopoulos, Dimitrios; Fotopoulos, Anaxagoras; Panagiotaras, Dionisios; Koulouras, Grigorios; Zisos, Athanasios; Nomicos, Constantinos; Louizi, Anna; Stonham, John

2013-01-01

This paper addresses the issues of self-organised critical behaviour of soil-radon and MHz-electromagnetic disorders during intense seismic activity in SW Greece. A significant radon signal is re-analysed for environmental influences with Fast Fourier Transform and multivariate statistics. Self-organisation of signals is investigated via fractal evolving techniques and detrended fluctuation analysis. New lengthy radon data are presented and analysed accordingly. The data did not show self-similarities. Similar analysis applied to new important concurrent MHz-electromagnetic signals revealed analogous behaviour to radon. The signals precursory value is discussed. - Highlights: ► New radon–MHz signals for an area with peculiar radon disorders on 2008. ► Use of spectrograms-multivariate statistics in analysing environmental parameters. ► Spectral fractal techniques and Detrended Fluctuation Analysis in all signals. ► Pre-earthquake signals followed fractional Brownian motion model. ► Hurst analysis showed persistent–antipersistent self-organised critical patterns.

Non-destructive testing of high heat flux components of fusion devices by infrared thermography: modeling and signal processing

International Nuclear Information System (INIS)

Cismondi, Fabio

2007-01-01

In Plasma Facing Components (PFCs) the joint of the CFC armour material onto the metallic CuCrZr heat sink needs to be significant defects free. Detection of material flaws is a major issue of the PFCs acceptance protocol. A Non-Destructive Technique (NDT) based upon active infrared thermography allows testing PFCs on SATIR tests bed in Cadarache. Up to now defect detection was based on the comparison of the surface temperature evolution of the inspected component with that of a supposed 'defect-free' one (used as a reference element). This work deals with improvement of thermal signal processing coming from SATIR. In particular the contributions of the thermal modelling and statistical signal processing converge in this work. As for thermal modelling, the identification of a sensitive parameter to defect presence allows improving the quantitative estimation of defect Otherwise Finite Element (FE) modeling of SATIR allows calculating the so called deterministic numerical tile. Statistical approach via the Monte Carlo technique extends the numerical tile concept to the numerical population concept. As for signal processing, traditional statistical treatments allow a better localization of the bond defect processing thermo-signal by itself, without utilising a reference signal. Moreover the problem of detection and classification of random signals can be solved by maximizing the signal-to-noise ratio. Two filters maximizing the signal-to-noise ratio are optimized: the stochastic matched filter aims at detects detection and the constrained stochastic matched filter aims at defects classification. Performances are quantified and methods are compared via the ROC curves. (author)

Retrospective dosimetry using Japanese brick quartz: A way forward despite an unstable fast decaying OSL signal

DEFF Research Database (Denmark)

Fujita, Hiroki; Jain, Mayank; Murray, A.S.

2011-01-01

signals has been carried out towards identification of common source traps. It is observed that OSL from Japanese brick quartz shows unusual luminescence characteristics; in particular, the initial fast decaying OSL signal contains a dominant (>90%) thermally unstable component related to the 85 °C TL...... peak, which necessitates a prior heat treatment. A single-aliquot regenerative-dose (SAR) protocol is developed and tested using thermal treatments intended to isolate a stable dosimetric signal. A minimum detection limit of 65 mGy is then estimated using this protocol. Following irradiation using 60Co...... of Japanese brick quartz examined here can be used to derive precise estimates of accident dose, and, possibly to distinguish between sources of gamma radiation in a nuclear accident. To our knowledge, this is the first report on the existence of an unstable fast decaying OSL signal in quartz derived from...

Activation of ERK signalling by Src family kinases (SFKs) in DRG neurons contributes to hydrogen peroxide (H2O2)-induced thermal hyperalgesia.

Science.gov (United States)

Singh, Ajeet Kumar; Vinayak, Manjula

2017-10-01

Concomitant generation of reactive oxygen species during tissue inflammation has been recognised as a major factor for the development and the maintenance of hyperalgesia, out of which H 2 O 2 is the major player. However, molecular mechanism of H 2 O 2 induced hyperalgesia is still obscure. The aim of present study is to analyse the mechanism of H 2 O 2 -induced hyperalgesia in rats. Intraplantar injection of H 2 O 2 (5, 10 and 20 µmoles/paw) induced a significant thermal hyperalgesia in the hind paw, confirmed by increased c-Fos activity in dorsal horn of spinal cord. Onset of hyperalgesia was prior to development of oxidative stress and inflammation. Rapid increase in phosphorylation of extracellular signal regulated kinase (ERK) was observed in neurons of dorsal root ganglia after 20 min of H 2 O 2 (10 µmoles/paw) administration, which gradually returned towards normal level within 24 h, following the pattern of thermal hyperalgesia. The expression of TNFR1 followed the same pattern and colocalised with pERK. ERK phosphorylation was observed in NF-200-positive and -negative neurons, indicating the involvement of ERK in C-fibres as well as in A-fibres. Intrathecal preadministration of Src family kinases (SFKs) inhibitor (PP1) and MEK inhibitor (PD98059) prevented H 2 O 2 induced augmentation of ERK phosphorylation and thermal hyperalgesia. Pretreatment of protein tyrosine phosphatases (PTPs) inhibitor (sodium orthovanadate) also diminished hyperalgesia, although it further increased ERK phosphorylation. Combination of orthovanadate with PP1 or PD98059 did not exhibit synergistic antihyperalgesic effect. The results demonstrate SFKs-mediated ERK activation and increased TNFR1 expression in nociceptive neurons during H 2 O 2 induced hyperalgesia. However, the role of PTPs in hyperalgesic behaviour needs further molecular analysis.

Understanding and eliminating artifact signals from diffusely scattered pump beam in measurements of rough samples by time-domain thermoreflectance (TDTR)

Energy Technology Data Exchange (ETDEWEB)

Sun, Bo [Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576 (Singapore); Koh, Yee Kan, E-mail: mpekyk@nus.edu.sg [Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576 (Singapore); Centre of Advanced 2D Materials, National University of Singapore, Singapore 117542 (Singapore)

2016-06-15

Time-domain thermoreflectance (TDTR) is a pump-probe technique frequently applied to measure the thermal transport properties of bulk materials, nanostructures, and interfaces. One of the limitations of TDTR is that it can only be employed to samples with a fairly smooth surface. For rough samples, artifact signals are collected when the pump beam in TDTR measurements is diffusely scattered by the rough surface into the photodetector, rendering the TDTR measurements invalid. In this paper, we systemically studied the factors affecting the artifact signals due to the pump beam leaked into the photodetector and thus established the origin of the artifact signals. We find that signals from the leaked pump beam are modulated by the probe beam due to the phase rotation induced in the photodetector by the illumination of the probe beam. As a result of the modulation, artifact signals due to the leaked pump beam are registered in TDTR measurements as the out-of-phase signals. We then developed a simple approach to eliminate the artifact signals due to the leaked pump beam. We verify our leak-pump correction approach by measuring the thermal conductivity of a rough InN sample, when the signals from the leaked pump beam are significant. We also discuss the advantages of our new method over the two-tint approach and its limitations. Our new approach enables measurements of the thermal conductivity of rough samples using TDTR.

Water chemistry and soil radon survey at the Poas volcano (Costa Rica

Directory of Open Access Journals (Sweden)

J. L. Seidel

2005-06-01

Full Text Available Radon-in-soil monitoring at the Poas volcano (Costa Rica has been performed together with water chemistry from the hot crater lake since 1981 and 1983 respectively. The results are discussed as a function of the eruptive evolution of the volcano over a 13 years period (1981-1994. It is shown that no definitely clear precursory radon signals have been recorded. On the contrary, ionic species concentrations are likely to be considered good precursors, together with the temperature variations of the crater lake water.

Synthesis, Characterization and Thermal Studies of Co(II), Ni(II), Cu ...

African Journals Online (AJOL)

NICO

2010-06-15

Jun 15, 2010 ... metal complexes was confirmed by thermal and IR data of the complexes. KEY WORDS. Synthesis ..... signals deshielded in the spectra of metal complexes, suggests coordination of .... micro analysis data of the complexes.

Seismic activity and thermal regime of low temperature fumaroles at Mt. Vesuvius in 2004-2011: distinguishing among seismic, volcanic and hydrological signals

Directory of Open Access Journals (Sweden)

Paola Cusano

2013-11-01

Full Text Available Seismological, soil temperature and hydrological data from Mt. Vesuvius are collected to characterize the present-day activity of the volcanic/hydrothermal system and to detect possible unrest-related phenomena. We present patterns of seismicity and soil temperature in the crater area during the period February 2004-December 2011. The temporal distribution of number and depth of Volcano-Tectonic earthquakes and the energy release are considered. Hourly data of soil temperature have been acquired since January 2004 in different locations along the rim and within the crater. The observed changes of temperature are studied to establish a temporal-based correlation with the volcanic activity and/or with external forcing, as variations of the regional and local stress field acting on the volcano or meteorological phenomena. The comparison between seismic activity and temperature data highlights significant variations possibly related to changes in fluid circulation in the hydrothermal system of the volcano. The common continuous observations start just before a very shallow earthquake occurred in August 2005, which was preceded by a thermal anomaly. This coincidence has been interpreted as related to fluid-driven rock fracturing, as observed in other volcanoes. For the successive temporal patterns, the seismicity rate and energy release are characterized by slight variations accompanied by changes in temperature. This evidence of reactivity of the fumarole thermal field to seismic strain can be used to discriminate between tectonic and volcanic signals at Mt. Vesuvius.

THERMAL PHASES OF EARTH-LIKE PLANETS: ESTIMATING THERMAL INERTIA FROM ECCENTRICITY, OBLIQUITY, AND DIURNAL FORCING

International Nuclear Information System (INIS)

Cowan, Nicolas B.; Voigt, Aiko; Abbot, Dorian S.

2012-01-01

In order to understand the climate on terrestrial planets orbiting nearby Sun-like stars, one would like to know their thermal inertia. We use a global climate model to simulate the thermal phase variations of Earth analogs and test whether these data could distinguish between planets with different heat storage and heat transport characteristics. In particular, we consider a temperate climate with polar ice caps (like the modern Earth) and a snowball state where the oceans are globally covered in ice. We first quantitatively study the periodic radiative forcing from, and climatic response to, rotation, obliquity, and eccentricity. Orbital eccentricity and seasonal changes in albedo cause variations in the global-mean absorbed flux. The responses of the two climates to these global seasons indicate that the temperate planet has 3× the bulk heat capacity of the snowball planet due to the presence of liquid water oceans. The obliquity seasons in the temperate simulation are weaker than one would expect based on thermal inertia alone; this is due to cross-equatorial oceanic and atmospheric energy transport. Thermal inertia and cross-equatorial heat transport have qualitatively different effects on obliquity seasons, insofar as heat transport tends to reduce seasonal amplitude without inducing a phase lag. For an Earth-like planet, however, this effect is masked by the mixing of signals from low thermal inertia regions (sea ice and land) with that from high thermal inertia regions (oceans), which also produces a damped response with small phase lag. We then simulate thermal light curves as they would appear to a high-contrast imaging mission (TPF-I/Darwin). In order of importance to the present simulations, which use modern-Earth orbital parameters, the three drivers of thermal phase variations are (1) obliquity seasons, (2) diurnal cycle, and (3) global seasons. Obliquity seasons are the dominant source of phase variations for most viewing angles. A pole-on observer

THERMAL PHASES OF EARTH-LIKE PLANETS: ESTIMATING THERMAL INERTIA FROM ECCENTRICITY, OBLIQUITY, AND DIURNAL FORCING

Energy Technology Data Exchange (ETDEWEB)

Cowan, Nicolas B. [Center for Interdisciplinary Exploration and Research in Astrophysics and Department of Physics and Astronomy, Northwestern University, 2131 Tech Drive, Evanston, IL 60208 (United States); Voigt, Aiko [Max Planck Institute for Meteorology, Bundesstr. 53, D-20146 Hamburg (Germany); Abbot, Dorian S., E-mail: n-cowan@nortwestern.edu [Department of Geophysical Sciences, University of Chicago, 5734 South Ellis Avenue, Chicago, IL 60637 (United States)

2012-09-20

In order to understand the climate on terrestrial planets orbiting nearby Sun-like stars, one would like to know their thermal inertia. We use a global climate model to simulate the thermal phase variations of Earth analogs and test whether these data could distinguish between planets with different heat storage and heat transport characteristics. In particular, we consider a temperate climate with polar ice caps (like the modern Earth) and a snowball state where the oceans are globally covered in ice. We first quantitatively study the periodic radiative forcing from, and climatic response to, rotation, obliquity, and eccentricity. Orbital eccentricity and seasonal changes in albedo cause variations in the global-mean absorbed flux. The responses of the two climates to these global seasons indicate that the temperate planet has 3 Multiplication-Sign the bulk heat capacity of the snowball planet due to the presence of liquid water oceans. The obliquity seasons in the temperate simulation are weaker than one would expect based on thermal inertia alone; this is due to cross-equatorial oceanic and atmospheric energy transport. Thermal inertia and cross-equatorial heat transport have qualitatively different effects on obliquity seasons, insofar as heat transport tends to reduce seasonal amplitude without inducing a phase lag. For an Earth-like planet, however, this effect is masked by the mixing of signals from low thermal inertia regions (sea ice and land) with that from high thermal inertia regions (oceans), which also produces a damped response with small phase lag. We then simulate thermal light curves as they would appear to a high-contrast imaging mission (TPF-I/Darwin). In order of importance to the present simulations, which use modern-Earth orbital parameters, the three drivers of thermal phase variations are (1) obliquity seasons, (2) diurnal cycle, and (3) global seasons. Obliquity seasons are the dominant source of phase variations for most viewing angles. A

Investigation of the ULF electromagnetic phenomena related to earthquakes. Contemporary achievements and the perspectives

Energy Technology Data Exchange (ETDEWEB)

Kopytenko, Y.; Ismagilov, V. [SPbF Izmiran, St. Petersbourg (Russian Federation); Hayakawa, M [The University of Electro-Communications, Chofu, Tokyo (Japan); Smirnova, N.; Troyan, V. [St. Petersbourg Univ., St Petersbourg (Russian Federation). Inst. of Physics; Peterson, T. [TFPLAB, Cleveland, OH (United States)

2001-04-01

The results of ULF electromagnetic signal observations in seismoactive regions prior to earthquakes are presented and discussed. The new differential measurement technique developed in SPbF IZMIRAN for location of the ULF emission sources of space and lithosphere origin is described. The MVC-2DS geohphysical instrumentation is introduced as a promising tool for registration of ULF signals related to earthquakes (both seismic and electromagnetic ones). Methods are proposed for ULF data processing to investigate the preparation processes in the earthquake source regions and to distinguish seismogenic signals. on the background of space pulsations. Some examples of application of those methods for study of the earthquake precursory signatures are presented. Perspectives of seismo-electromagnetic tomography experiments in seismoactive regions, using MVC-2DS technique, are discussed in relation to the development of earthquake prediction methods.

MR imaging and histopathologic correlations of thermal injuries induced by interstitial laser applications

International Nuclear Information System (INIS)

Anzai, Y.; Lufkin, R.B.; Castro, D.J.; Farahani, K.; Chen, H.W.; Hirchowiz, S.

1991-01-01

Interstitial laser phototherapy for deep-seated tumors may become an attractive therapeutic modality when a noninvasive, accurate monitoring system is developed. In this paper, to devaluate the ability of MR imaging to differentiate reversible and irreversible thermal injuries induced by laser therapy, the precise correlation of MR and histopathologic findings are investigated in the in vivo model. Nd:YAG lasers were applied to normal musculature of rabbits, and MR examinations were performed immediately after laser exposure and followed up for up to 10 weeks. The sequential MR images were correlated with histopathologic findings. T2-weighted MR imaging clearly showed laser-induced thermal injuries on any postoperative day. MR imaging of acute thermal injuries showed a central cavity, low-signal zone of coagulative necrosis and a peripheral high-signal layer of interstitial edema. The infiltration of neutrophils followed by fibrovascular response was identified on the marginal edema layer after 6 postoperative days

The effect of opioid receptor blockade on the neural processing of thermal stimuli.

Directory of Open Access Journals (Sweden)

Eszter D Schoell

Full Text Available The endogenous opioid system represents one of the principal systems in the modulation of pain. This has been demonstrated in studies of placebo analgesia and stress-induced analgesia, where anti-nociceptive activity triggered by pain itself or by cognitive states is blocked by opioid antagonists. The aim of this study was to characterize the effect of opioid receptor blockade on the physiological processing of painful thermal stimulation in the absence of cognitive manipulation. We therefore measured BOLD (blood oxygen level dependent signal responses and intensity ratings to non-painful and painful thermal stimuli in a double-blind, cross-over design using the opioid receptor antagonist naloxone. On the behavioral level, we observed an increase in intensity ratings under naloxone due mainly to a difference in the non-painful stimuli. On the neural level, painful thermal stimulation was associated with a negative BOLD signal within the pregenual anterior cingulate cortex, and this deactivation was abolished by naloxone.

Lock-in thermal imaging for the early-stage detection of cutaneous melanoma: a feasibility study.

Science.gov (United States)

Bonmarin, Mathias; Le Gal, Frédérique-Anne

2014-04-01

This paper theoretically evaluates lock-in thermal imaging for the early-stage detection of cutaneous melanoma. Lock-in thermal imaging is based on the periodic thermal excitation of the specimen under test. Resulting surface temperature oscillations are recorded with an infrared camera and allow the detection of variations of the sample's thermophysical properties under the surface. In this paper, the steady-state and transient skin surface temperatures are numerically derived for a different stage of development of the melanoma lesion using a two-dimensional axisymmetric multilayer heat-transfer model. The transient skin surface temperature signals are demodulated according to the digital lock-in principle to compute both a phase and an amplitude image of the lesions. The phase image can be advantageously used to accurately detect cutaneous melanoma at an early stage of development while the maximal phase shift can give precious information about the lesion invasion depth. The ability of lock-in thermal imaging to suppress disturbing subcutaneous thermal signals is demonstrated. The method is compared with the previously proposed pulse-based approaches, and the influence of the modulation frequency is further discussed. Copyright © 2014 Elsevier Ltd. All rights reserved.

Perceptual-Semantic Congruency Facilitates Semantic Discrimination of Thermal Qualities

Directory of Open Access Journals (Sweden)

Yizhen Zhou

2017-12-01

Full Text Available The ability to sense temperature is vital to our life. It signals the environmental condition, reflects the physiological conditions of our own body, and generates feelings of pleasantness or unpleasantness. Moreover, recent studies have demonstrated implicit associations between physical temperature and social/emotional concepts, suggesting the processing of temperature may even influence cognition. In this work, we examined the effect of physical warmth and coldness on semantic cognition. Participants performed speeded target categorization for thermal descriptors in the form of semantic words or illustrative figures representing the thermal qualities “warm” or “cold” while physical thermal stimulation was presented. We compared the average reaction time (RT for the congruent and incongruent conditions managed by response key assignments. In the congruent condition, the response key for the symbol associated with warmth (coldness was assigned to the hand with warm (cold thermal stimulation, and in the incongruent condition the key assignment was reversed. Our results demonstrate that the average RT in the congruent condition was faster than in the incongruent one for both forms of thermal descriptors, suggesting that the experience of physical temperature facilitates the internal processing of the meaning of thermal quality.

Equipment for dekryptonation thermal analysis

International Nuclear Information System (INIS)

Lukac, P.; Pruzinec, J.

Emanation thermal analysis is used for studying changes in the dynamic temperature conditions during kinetics studies of some reactions in solids. A kryptonated sample is placed in a furnace with a programmable temperature controller. 85 Kr released from the sample is entrapped by the carrier gas in a through-flow Geiger-Mueller detector. The detector signal is processed into an integral form and recorded. Examples are given of the study of modification transformations in NH 4 NO 3 , pearlite and PVC. (M.D.)

Space Shuttle Communications Coverage Analysis for Thermal Tile Inspection

Science.gov (United States)

Kroll, Quin D.; Hwu, Shian U.; Upanavage, Matthew; Boster, John P.; Chavez, Mark A.

2009-01-01

The space shuttle ultra-high frequency Space-to-Space Communication System has to provide adequate communication coverage for astronauts who are performing thermal tile inspection and repair on the underside of the space shuttle orbiter (SSO). Careful planning and quantitative assessment are necessary to ensure successful system operations and mission safety in this work environment. This study assesses communication systems performance for astronauts who are working in the underside, non-line-of-sight shadow region on the space shuttle. All of the space shuttle and International Space Station (ISS) transmitting antennas are blocked by the SSO structure. To ensure communication coverage at planned inspection worksites, the signal strength and link margin between the SSO/ISS antennas and the extravehicular activity astronauts, whose line-of-sight is blocked by vehicle structure, was analyzed. Investigations were performed using rigorous computational electromagnetic modeling techniques. Signal strength was obtained by computing the reflected and diffracted fields along the signal propagation paths between transmitting and receiving antennas. Radio frequency (RF) coverage was determined for thermal tile inspection and repair missions using the results of this computation. Analysis results from this paper are important in formulating the limits on reliable communication range and RF coverage at planned underside inspection and repair worksites.

Thermal neutron imaging in an active interrogation environment

International Nuclear Information System (INIS)

Vanier, P.E.; Forman, L.; Norman, D.R.

2009-01-01

We have developed a thermal-neutron coded-aperture imager that reveals the locations of hydrogenous materials from which thermal neutrons are being emitted. This imaging detector can be combined with an accelerator to form an active interrogation system in which fast neutrons are produced in a heavy metal target by means of excitation by high energy photons. The photo-induced neutrons can be either prompt or delayed, depending on whether neutronemitting fission products are generated. Provided that there are hydrogenous materials close to the target, some of the photo-induced neutrons slow down and emerge from the surface at thermal energies. These neutrons can be used to create images that show the location and shape of the thermalizing materials. Analysis of the temporal response of the neutron flux provides information about delayed neutrons from induced fission if there are fissionable materials in the target. The combination of imaging and time-of-flight discrimination helps to improve the signal-to-background ratio. It is also possible to interrogate the target with neutrons, for example using a D-T generator. In this case, an image can be obtained from hydrogenous material in a target without the presence of heavy metal. In addition, if fissionable material is present in the target, probing with fast neutrons can stimulate delayed neutrons from fission, and the imager can detect and locate the object of interest, using appropriate time gating. Operation of this sensitive detection equipment in the vicinity of an accelerator presents a number of challenges, because the accelerator emits electromagnetic interference as well as stray ionizing radiation, which can mask the signals of interest.

A precursory ULF signature for the Chi-Chi earthquake in Taiwan

Directory of Open Access Journals (Sweden)

Y. Akinaga

2001-01-01

Full Text Available ULF emission data at Lunping (epicentral distance, 120 km have been analysed for the Chi-Chi earthquake (with magnitude 7.6 and depth of 11 km in Taiwan which occurred on 21 September 1999. Simple intensity analyses have not yielded any significant results but we have found, based on the analysis of polarization (the ratio of vertical magnetic field component Z to the horizontal component G, that the polarization (Z/G showed a significant enhancement for two months before the earthquake. This kind of temporal evolution of polarization seems to be very similar to previous results, so that it is highly likely that this phenomenon may be associated with the Chi-Chi earthquake. Also, the comparison of the results of polarization analyses, by changing the signal threshold, has given us an approximate intensity of the seismogenic emission of the order of the monthly mean value.

Inter-vehicle gap statistics on signal-controlled crossroads

International Nuclear Information System (INIS)

Krbalek, Milan

2008-01-01

We investigate a microscopical structure in a chain of cars waiting at a red signal on signal-controlled crossroads. A one-dimensional space-continuous thermodynamical model leading to an excellent agreement with the data measured is presented. Moreover, we demonstrate that an inter-vehicle spacing distribution disclosed in relevant traffic data agrees with the thermal-balance distribution of particles in the thermodynamical traffic gas (discussed in [1]) with a high inverse temperature (corresponding to a strong traffic congestion). Therefore, as we affirm, such a system of stationary cars can be understood as a specific state of the traffic sample operating inside a congested traffic stream

Stochastic modeling of thermal fatigue crack growth

CERN Document Server

Radu, Vasile

2015-01-01

The book describes a systematic stochastic modeling approach for assessing thermal-fatigue crack-growth in mixing tees, based on the power spectral density of temperature fluctuation at the inner pipe surface. It shows the development of a frequency-temperature response function in the framework of single-input, single-output (SISO) methodology from random noise/signal theory under sinusoidal input. The frequency response of stress intensity factor (SIF) is obtained by a polynomial fitting procedure of thermal stress profiles at various instants of time. The method, which takes into account the variability of material properties, and has been implemented in a real-world application, estimates the probabilities of failure by considering a limit state function and Monte Carlo analysis, which are based on the proposed stochastic model. Written in a comprehensive and accessible style, this book presents a new and effective method for assessing thermal fatigue crack, and it is intended as a concise and practice-or...

Longitudinal On-Column Thermal Modulation for Comprehensive Two-Dimensional Liquid Chromatography.

Science.gov (United States)

Creese, Mari E; Creese, Mathew J; Foley, Joe P; Cortes, Hernan J; Hilder, Emily F; Shellie, Robert A; Breadmore, Michael C

2017-01-17

Longitudinal on-column thermal modulation for comprehensive two-dimensional liquid chromatography is introduced. Modulation optimization involved a systematic investigation of heat transfer, analyte retention, and migration velocity at a range of temperatures. Longitudinal on-column thermal modulation was realized using a set of alkylphenones and compared to a conventional valve-modulator employing sample loops. The thermal modulator showed a reduced modulation-induced pressure impact than valve modulation, resulting in reduced baseline perturbation by a factor of 6; yielding a 6-14-fold improvement in signal-to-noise. A red wine sample was analyzed to demonstrate the potential of the longitudinal on-column thermal modulator for separation of a complex sample. Discrete peaks in the second dimension using the thermal modulator were 30-55% narrower than with the valve modulator. The results shown herein demonstrate the benefits of an active focusing modulator, such as reduced detection limits and increased total peak capacity.

Thermal-wave balancing flow sensor with low-drift power feedback

NARCIS (Netherlands)

Dijkstra, Marcel; Lammerink, Theodorus S.J.; Pjetri, O.; de Boer, Meint J.; Berenschot, Johan W.; Wiegerink, Remco J.; Elwenspoek, Michael Curt

2014-01-01

A control system using a low-drift power-feedback signal was implemented applying thermal waves, giving a sensor output independent of resistance drift and thermo-electric offset voltages on interface wires. Kelvin-contact sensing and power control is used on heater resistors, thereby inhibiting the

Earthquake precursory events around epicenters and local active faults; the cases of two inland earthquakes in Iran

Science.gov (United States)

Valizadeh Alvan, H.; Mansor, S.; Haydari Azad, F.

2012-12-01

The possibility of earthquake prediction in the frame of several days to few minutes before its occurrence has stirred interest among researchers, recently. Scientists believe that the new theories and explanations of the mechanism of this natural phenomenon are trustable and can be the basis of future prediction efforts. During the last thirty years experimental researches resulted in some pre-earthquake events which are now recognized as confirmed warning signs (precursors) of past known earthquakes. With the advances in in-situ measurement devices and data analysis capabilities and the emergence of satellite-based data collectors, monitoring the earth's surface is now a regular work. Data providers are supplying researchers from all over the world with high quality and validated imagery and non-imagery data. Surface Latent Heat Flux (SLHF) or the amount of energy exchange in the form of water vapor between the earth's surface and atmosphere has been frequently reported as an earthquake precursor during the past years. The accumulated stress in the earth's crust during the preparation phase of earthquakes is said to be the main cause of temperature anomalies weeks to days before the main event and subsequent shakes. Chemical and physical interactions in the presence of underground water lead to higher water evaporation prior to inland earthquakes. On the other hand, the leak of Radon gas occurred as rocks break during earthquake preparation causes the formation of airborne ions and higher Air Temperature (AT) prior to main event. Although co-analysis of direct and indirect observation for precursory events is considered as a promising method for future successful earthquake prediction, without proper and thorough knowledge about the geological setting, atmospheric factors and geodynamics of the earthquake-prone regions we will not be able to identify anomalies due to seismic activity in the earth's crust. Active faulting is a key factor in identification of the

Parameterization and Observability Analysis of Scalable Battery Clusters for Onboard Thermal Management

Science.gov (United States)

2011-12-01

which includes the current from regenerative braking . Repeated UAC cycles are used as the model input to generate the surface temperature Ts to test...battery thermal dynamics is the key to an effective thermal management system and to main- tain safety, performance, and life longevity of these Li-Ion...the current and surface temperature of the battery, which are the commonly mea- sured signals in a vehicle battery management system . It is shown that

Extreme Temperature Performance of Automotive-Grade Small Signal Bipolar Junction Transistors

Science.gov (United States)

Boomer, Kristen; Damron, Benny; Gray, Josh; Hammoud, Ahmad

2018-01-01

Electronics designed for space exploration missions must display efficient and reliable operation under extreme temperature conditions. For example, lunar outposts, Mars rovers and landers, James Webb Space Telescope, Europa orbiter, and deep space probes represent examples of missions where extreme temperatures and thermal cycling are encountered. Switching transistors, small signal as well as power level devices, are widely used in electronic controllers, data instrumentation, and power management and distribution systems. Little is known, however, about their performance in extreme temperature environments beyond their specified operating range; in particular under cryogenic conditions. This report summarizes preliminary results obtained on the evaluation of commercial-off-the-shelf (COTS) automotive-grade NPN small signal transistors over a wide temperature range and thermal cycling. The investigations were carried out to establish a baseline on functionality of these transistors and to determine suitability for use outside their recommended temperature limits.

Preseismic anomalies in soil-gas radon associated with 2016 M 6.6 Meinong earthquake, Southern Taiwan

Directory of Open Access Journals (Sweden)

Ching-Chou Fu

2017-01-01

Full Text Available Taiwan is tectonically situated in a terrain resulting from the oblique collision between the Philippine Sea plate and the continental margin of the Asiatic plate, with a continuous stress causing the density of strong-moderate earthquakes and regional active faults. The continuous time series of soil radon for earthquake studies have been recorded and some significant variations associated with strong earthquakes have been observed. Earthquake prediction is not still operative but these correlations should be added to the literature about seismo-geochemical transients associated to strong earthquakes. Rain-pore pressure related variations, crustal weakness at the studied faults system is consistent with the simultaneous radon anomalies observed. During the observations, a significant increase of soil radon concentrations was observed at Chunglun-T1 (CL-T1, Hsinhua (HH, Pingtung (PT, and Chihshan (CS stations approximately two weeks before the Meinong earthquake (ML = 6.6, 6 February 2016 in Southern Taiwan. The precursory changes in a multi-stations array may reflect the preparation stage of a large earthquake. Precursory signals are observed simultaneously and it can apply certain algorithms the approximate location and magnitude of the impending earthquake.

Towards dating Quaternary sediments using the quartz Violet Stimulated Luminescence (VSL) signal

DEFF Research Database (Denmark)

Ankjærgaard, C.; Jain, Mayank; Wallinga, J.

2013-01-01

Quaternary sediments using the violet (402 nm) stimulated luminescence (VSL) signal of quartz.We develop and test a new post-blue VSL single aliquot regenerative dose dating protocol, and demonstrate that the VSL signal originates from a deep trap at about 1.9 eV with a thermal lifetime of 1011 years at 10......Quartz optically stimulated luminescence (OSL) dating is widely used to determine the time of deposition and burial of Late Quaternary sediments. Application of the method is usually limited to the past 150,000 years due to early saturation of the OSL signal. Here we explore the potential to date...

Thermally induced all-optical inverter and dynamic hysteresis loops in graphene oxide dispersions.

Science.gov (United States)

Melle, Sonia; Calderón, Oscar G; Egatz-Gómez, Ana; Cabrera-Granado, E; Carreño, F; Antón, M A

2015-11-01

We experimentally study the temporal dynamics of amplitude-modulated laser beams propagating through a water dispersion of graphene oxide sheets in a fiber-to-fiber U-bench. Nonlinear refraction induced in the sample by thermal effects leads to both phase reversing of the transmitted signals and dynamic hysteresis in the input-output power curves. A theoretical model including beam propagation and thermal lensing dynamics reproduces the experimental findings.

On the sensitivity of FPPE - TWRC method in thermal effusivity investigations of solids

International Nuclear Information System (INIS)

Dadarlat, Dorin; Streza, Mihaela; Pop, Mircea N; Tosa, Valer

2009-01-01

The front detection configuration (FPPE) together with the thermal-wave-resonator-cavity (TWRC) method was used for direct measurement of the thermal effusivity of solid materials inserted as backings in the FPPE detection cell. It was demonstrated that the normalized phase of the FPPE signal has an oscillating dependence as a function of sample's thickness. The paper presents experimental results on solid materials, with various values of thermal effusivity (Cu, brass, steel, bakelite, wood). A study of the sensitivity of the technique for different liquid/backing effusivity ratios is performed. The highest sensitivity was obtained when investigating solids with values of thermal effusivity not far from the effusivity of the liquid layer of the detection cell.

Photoacoustic thermal characterization of Al{sub 2}O{sub 3}-Ag ceramic nanocomposites

Energy Technology Data Exchange (ETDEWEB)

George, Sajan D. [Institut fuer Nano- und Mikroprozesstechnik, Leibniz Universitaet Hannover, Callinstrasse 36, D 30167, Hannover (Germany)]|[International School of Photonics, Cochin University of Science and Technology, Cochin 682022 (India)], E-mail: george@nmp.uni-hannover.de; Anappara, Aji A. [NEST-INFM and Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa (Italy)]|[University College, Thiruvanathapuram 695001 (India)]|[Ceramic Technology Division, Regional Research Laboratory, CSIR, Thiruvanathapuram 695019 (India); Warrier, P.R.S. [University College, Thiruvanathapuram 695001 (India); Warrier, K.G.K. [Ceramic Technology Division, Regional Research Laboratory, CSIR, Thiruvanathapuram 695019 (India); Radhakrishnan, P.; Nampoori, V.P.N.; Vallabhan, C.P.G. [International School of Photonics, Cochin University of Science and Technology, Cochin 682022 (India)

2008-09-15

Laser-induced nondestructive photoacoustic (PA) technique has been employed to determine the thermal diffusivity of nanometal (Ag) dispersed ceramic alumina matrix sintered at different temperatures. The thermal diffusivity values are evaluated by knowing the transition frequency from the amplitude spectrum of PA signal using the one-dimensional heat flow model of Rosencwaig and Gersho. Analysis of the data shows that heat transport and hence the thermal diffusivity value is greatly affected by the influence of incorporation of foreign atom. It is also seen that sintering temperature affects the thermal diffusivity value in a substantial manner. The results are interpreted in terms of variation in porosity and carrier-assisted heat transport mechanism in nanometal dispersed ceramics.

Investigation of Thermal Properties of High-Density Polyethylene/Aluminum Nanocomposites by Photothermal Infrared Radiometry

Science.gov (United States)

Koca, H. D.; Evgin, T.; Horny, N.; Chirtoc, M.; Turgut, A.; Tavman, I. H.

2017-12-01

In this study, thermal properties of high-density polyethylene (HDPE) filled with nanosized Al particles (80 nm) were investigated. Samples were prepared using melt mixing method up to filler volume fraction of 29 %, followed by compression molding. By using modulated photothermal radiometry (PTR) technique, thermal diffusivity and thermal effusivity were obtained. The effective thermal conductivity of nanocomposites was calculated directly from PTR measurements and from the measurements of density, specific heat capacity (by differential scanning calorimetry) and thermal diffusivity (obtained from PTR signal amplitude and phase). It is concluded that the thermal conductivity of HDPE composites increases with increasing Al fraction and the highest effective thermal conductivity enhancement of 205 % is achieved at a filler volume fraction of 29 %. The obtained results were compared with the theoretical models and experimental data given in the literature. The results demonstrate that Agari and Uno, and Cheng and Vachon models can predict well the thermal conductivity of HDPE/Al nanocomposites in the whole range of Al fractions.

Effect of the crystallinity in the Tl signal induced by the gamma radiation in Al2O3: Eu obtained by the sol gel method

International Nuclear Information System (INIS)

Mendoza A, D.; Gonzalez M, P.R.; Custodio, E.; Rubio, E.; Rodriguez L, V.

2004-01-01

In this work the synthesis and characterization process of Al 2 O 3 and Al 2 O 3 : Eu by sol gel method is reported. A previous thermal treatment at 500 and 1000 C on the material powder type showed a notable influences on the thermoluminescent signal induced by the gamma radiation, such that the intensity thermoluminescent signal produced by samples with thermal treatment at 1000 C is much bigger that thermoluminescent signal produced by samples thermal treatment at 500 C. In order to explain this behavior, an analysis for X-ray diffraction and electron microscopy was also realized. The results show a notably influence of the crystalline array and the microstructure on the thermoluminescent behavior of the alumina. (Author)

In Situ Acoustic Monitoring of Thermal Spray Process Using High-Frequency Impulse Measurements

Science.gov (United States)

Tillmann, Wolfgang; Walther, Frank; Luo, Weifeng; Haack, Matthias; Nellesen, Jens; Knyazeva, Marina

2018-01-01

In order to guarantee their protective function, thermal spray coatings must be free from cracks, which expose the substrate surface to, e.g., corrosive media. Cracks in thermal spray coatings are usually formed because of tensile residual stresses. Most commonly, the crack occurrence is determined after the thermal spraying process by examination of metallographic cross sections of the coating. Recent efforts focus on in situ monitoring of crack formation by means of acoustic emission analysis. However, the acoustic signals related to crack propagation can be absorbed by the noise of the thermal spraying process. In this work, a high-frequency impulse measurement technique was applied to separate different acoustic sources by visualizing the characteristic signal of crack formation via quasi-real-time Fourier analysis. The investigations were carried out on a twin wire arc spraying process, utilizing FeCrBSi as a coating material. The impact of the process parameters on the acoustic emission spectrum was studied. Acoustic emission analysis enables to obtain global and integral information on the formed cracks. The coating morphology and coating defects were inspected using light microscopy on metallographic cross sections. Additionally, the resulting crack patterns were imaged in 3D by means of x-ray microtomography.

Light higgsino dark matter from non-thermal cosmology

Energy Technology Data Exchange (ETDEWEB)

Aparicio, Luis [ICTP,Strada Costiera 11, Trieste 34014 (Italy); Cicoli, Michele [ICTP,Strada Costiera 11, Trieste 34014 (Italy); Dipartimento di Fisica e Astronomia, Università di Bologna,via Irnerio 46, 40126 Bologna (Italy); INFN, Sezione di Bologna,via Irnerio 46, 40126 Bologna (Italy); Dutta, Bhaskar [Department of Physics and Astronomy,Mitchell Institute for Fundamental Physics and Astronomy,TAMU, College Station, TX 77843-4242 (United States); Muia, Francesco [Dipartimento di Fisica e Astronomia, Università di Bologna,via Irnerio 46, 40126 Bologna (Italy); INFN, Sezione di Bologna,via Irnerio 46, 40126 Bologna (Italy); Quevedo, Fernando [ICTP,Strada Costiera 11, Trieste 34014 (Italy); DAMTP, Centre for Mathematical Sciences,Wilberforce Road, Cambridge, CB3 0WA (United Kingdom)

2016-11-08

We study the scenario of higgsino dark matter in the context of a non-standard cosmology with a period of matter domination prior to Big Bang nucleosynthesis. Matter domination changes the dark matter relic abundance if it ends via reheating to a temperature below the higgsino thermal freeze-out temperature. We perform a model independent analysis of the higgsino dark matter production in such scenario. We show that light higgsino-type dark matter is possible for reheating temperatures close to 1 GeV. We study the impact of dark matter indirect detection and collider physics in this context. We show that Fermi-LAT data rule out non-thermal higgsinos with masses below 300 GeV. Future indirect dark matter searches from Fermi-LAT and CTA will be able to cover essentially the full parameter space. Contrary to the thermal case, collider signals from a 100 TeV collider could fully test the non-thermal higgsino scenario. In the second part of the paper we discuss the motivation of such non-thermal cosmology from the perspective of string theory with late-time decaying moduli for both KKLT and LVS moduli stabilisation mechanisms. We finally describe the impact of embedding higgsino dark matter in these scenarios.

Comprehensive NMR analysis of compositional changes of black garlic during thermal processing.

Science.gov (United States)

Liang, Tingfu; Wei, Feifei; Lu, Yi; Kodani, Yoshinori; Nakada, Mitsuhiko; Miyakawa, Takuya; Tanokura, Masaru

2015-01-21

Black garlic is a processed food product obtained by subjecting whole raw garlic to thermal processing that causes chemical reactions, such as the Maillard reaction, which change the composition of the garlic. In this paper, we report a nuclear magnetic resonance (NMR)-based comprehensive analysis of raw garlic and black garlic extracts to determine the compositional changes resulting from thermal processing. (1)H NMR spectra with a detailed signal assignment showed that 38 components were altered by thermal processing of raw garlic. For example, the contents of 11 l-amino acids increased during the first step of thermal processing over 5 days and then decreased. Multivariate data analysis revealed changes in the contents of fructose, glucose, acetic acid, formic acid, pyroglutamic acid, cycloalliin, and 5-(hydroxymethyl)furfural (5-HMF). Our results provide comprehensive information on changes in NMR-detectable components during thermal processing of whole garlic.

Improved thermal cycling durability and PCR compatibility of polymer coated quantum dot

International Nuclear Information System (INIS)

Xun Zhe; Guan Yifu; Zhao Xiaoyun

2013-01-01

Quantum dots have experienced rapid development in imaging, labeling and sensing in medicine and life science. To be suitable for polymerase chain reaction (PCR) assay, we have tested QD thermal cycling durability and compatibility, which have not been addressed in previous reports. In this study, we synthesized CdSe/ZnS QDs with a surface modification with high-MW amphiphilic copolymers and observed that Mg 2+ ions in the PCR reaction could induce the QDs to precipitate and reduce their fluorescence signal significantly after thermal cycling. To overcome this problem, we used mPEG2000 to conjugate the QD surface for further protection, and found that this modification enables QDs to endure 40 thermal cycles in the presence of other components essential for PCR reactions. We have also identified that QDs have different effects on rTaq and Ex Taq polymerization systems. A high QD concentration could apparently reduce the PCR efficiency, but this inhibition was relieved significantly in the Ex PCR system as the concentration of Ex Taq polymerase was increased. Real-time PCR amplification results showed that QDs could provide a sufficiently measurable fluorescence signal without excessively inhibiting the DNA amplification. Based on this improved thermal cycling durability and compatibility with the PCR system, QDs have the potential to be developed as stable fluorescent sensors in PCR and real-time PCR amplification. (paper)

Evidence from acoustic imaging for submarine volcanic activity in 2012 off the west coast of El Hierro (Canary Islands, Spain)

Science.gov (United States)

Pérez, Nemesio M.; Somoza, Luis; Hernández, Pedro A.; de Vallejo, Luis González; León, Ricardo; Sagiya, Takeshi; Biain, Ander; González, Francisco J.; Medialdea, Teresa; Barrancos, José; Ibáñez, Jesús; Sumino, Hirochika; Nogami, Kenji; Romero, Carmen

2014-12-01

of El Hierro. These precursory signals have revealed important to improve and optimize the detection of early warning signals of volcanic unrest episodes at El Hierro.

Optoacoustic monitoring of cutting efficiency and thermal damage during laser ablation.

Science.gov (United States)

Bay, Erwin; Douplik, Alexandre; Razansky, Daniel

2014-05-01

Successful laser surgery is characterized by a precise cut and effective hemostasis with minimal collateral thermal damage to the adjacent tissues. Consequently, the surgeon needs to control several parameters, such as power, pulse repetition rate, and velocity of movements. In this study we propose utilizing optoacoustics for providing the necessary real-time feedback of cutting efficiency and collateral thermal damage. Laser ablation was performed on a bovine meat slab using a Q-switched Nd-YAG laser (532 nm, 4 kHz, 18 W). Due to the short pulse duration of 7.6 ns, the same laser has also been used for generation of optoacoustic signals. Both the shockwaves, generated due to tissue removal, as well as the normal optoacoustic responses from the surrounding tissue were detected using a single broadband piezoelectric transducer. It has been observed that the rapid reduction in the shockwave amplitude occurs as more material is being removed, indicating decrease in cutting efficiency, whereas gradual decrease in the optoacoustic signal likely corresponds to coagulation around the ablation crater. Further heating of the surrounding tissue leads to carbonization accompanied by a significant shift in the optoacoustic spectra. Our results hold promise for real-time monitoring of cutting efficiency and collateral thermal damage during laser surgery. In practice, this could eventually facilitate development of automatic cut-off mechanisms that will guarantee an optimal tradeoff between cutting and heating while avoiding severe thermal damage to the surrounding tissues.

Two-laser thermal-lens determination of phosphorus in silicon

International Nuclear Information System (INIS)

Grishko, V.I.; Gol'dshtein, M.M.; Grishko, V.P.; Yudelevich, I.G.

1986-01-01

Laser thermal-lens spectrophotometry is a high-sensitivity method of measuring absorptivity, where the signal is the relative intensity change at the beam center after passage through the medium, which absorbs at the laser wavelength. The two-lens method is discussed here which employs a high-power laser to induce the lens, while the absorptivity is measured from the intensity change in the beam from a continous wave low-power test laser at a wavelength different from that for the inducing one. This paper uses two-laser thermal-lens techniques to determine phosphorus in silicon. Phosphorus is determined as the ionic association of molybdophosphoric acid with auramine

Study of thermal effects in superconducting RF cavities; Etude des effets thermiques dans le cavites supraconductrices

Energy Technology Data Exchange (ETDEWEB)

Bousson, S.; Caruette, A.; Fouaidy, M.; Hammoudi, N.; Junquera, T.; Lesrel, J.; Yaniche, J.F. [Services Techniques, Inst. de Physique Nucleaire, Paris-11 Univ., 91 - Orsay (France)

1999-11-01

A high speed thermometric system equipped with 64 fixed surface thermometers is used to investigate thermal effects in several 3 GHz cavities. An evaluation of the time response of our thermometers is presented. A method based on RF signal analysis is proposed to evaluate the normal zone propagation rate during thermal breakdown. (authors) 2 refs., 3 figs.

Natural and laboratory TT-OSL dose response curves: Testing the lifetime of the TT-OSL signal in nature

International Nuclear Information System (INIS)

Chapot, M.S.; Roberts, H.M.; Duller, G.A.T.; Lai, Z.P.

2016-01-01

This study compares natural and laboratory generated thermally transferred optically stimulated luminescence (TT-OSL) dose response curves (DRCs) for fine-grain quartz extracts from the Luochuan loess section in central China. Both DRCs saturate at high doses relative to the quartz OSL signal; the natural TT-OSL DRC saturates at about 2200 Gy and laboratory DRCs saturate at about 2700 Gy. However, the natural and laboratory TT-OSL DRCs deviate from one another at circa 150 Gy resulting in TT-OSL equivalent dose underestimation relative to palaeodoses expected from dose rates and independent age control. The lifetime of the TT-OSL signal at 10 °C, calculated from values of trap parameters E and s, is compared against the value for lifetime of the TT-OSL signal in nature at average burial temperature as determined from the age underestimation caused by deviation of the natural and laboratory generated DRCs. These two independent assessments of TT-OSL signal lifetime at Luochuan give similar values, suggesting that laboratory measurements of thermal stability reflect natural burial lifetimes and can potentially be used to correct TT-OSL ages for the difference between natural and laboratory dose response curves. - Highlights: • Natural and laboratory TT-OSL DRCs deviate at ∼150 Gy but saturate at higher doses. • TT-OSL signal lifetime at 10 °C calculated from measured E and s values is ∼180 ka. • TT-OSL signal lifetime at Luochuan estimated from the DRCs' deviation is ∼175 ka. • Natural and laboratory TT-OSL DRC deviation may be caused by low thermal stability. • Laboratory measurements of signal lifetime may be able to correct old TT-OSL ages.

Temperature measurement by thermal strain imaging with diagnostic power ultrasound, with potential for thermal index determination.

Science.gov (United States)

Liang, Hai-Dong; Zhou, Li-Xia; Wells, Peter N T; Halliwell, Michael

2009-05-01

Over the years, there has been a substantial increase in acoustic exposure in diagnostic ultrasound as new imaging modalities with higher intensities and frame rates have been introduced; and more electronic components have been packed into the probe head, so that there is a tendency for it to become hotter. With respect to potential thermal effects, including those which may be hazardous occurring during ultrasound scanning, there is a correspondingly growing need for in vivo techniques to guide the operator as to the actual temperature rise occurring in the examined tissues. Therefore, an in vivo temperature estimator would be of considerable practical value. The commonly-used method of tissue thermal index (TI) measurement with a hydrophone in water could underestimate the actual value of TI (in one report by as much as 2.9 times). To obtain meaningful results, it is necessary to map the temperature elevation in 2-D (or 3-D) space. We present methodology, results and validation of a 2-D spatial and temporal thermal strain ultrasound temperature estimation technique in phantoms, and its apparently novel application in tracking the evolution of heat deposition at diagnostic exposure levels. The same ultrasound probe is used for both transmission and reception. The displacement and thermal strain estimation methods are similar to those used in high-intensity focused ultrasound thermal monitoring. The use of radiofrequency signals permits the application of cross correlation as a similarity measurement for tracking feature displacement. The displacement is used to calculate the thermal strain directly related to the temperature rise. Good agreement was observed between the temperature rise and the ultrasound power and scan duration. Thermal strain up to 1.4% was observed during 4000-s scan. Based on the results obtained for the temperature range studied in this work, the technique demonstrates potential for applicability in phantom (and possibly in vivo tissue

Applications of autoassociative neural networks for signal validation in accident management

International Nuclear Information System (INIS)

Fantoni, P.; Mazzola, A.

1994-01-01

The OECD Halden Reactor Project has been working for several years with computer based systems for determination on plant status including early fault detection and signal validation. The method here presented explores the possibility to use a neural network approach to validate important process signals during normal and abnormal plant conditions. In BWR plants, signal validation has two important applications: reliable thermal limits calculation and reliable inputs to other computerized systems that support the operator during accident scenarious. This work shows how a properly trained autoassociative neural network can promptly detect faulty process signal measurements and produce a best estimate of the actual process value. Noise has been artificially added to the input to evaluate the network ability to respond in a very low signal to noise ratio environment. Training and test datasets have been simulated by the real time transient simulator code APROS. Future development addresses the validation of the model through the use of real data from the plant. (author). 5 refs, 17 figs

Coral thermal tolerance: tuning gene expression to resist thermal stress.

Directory of Open Access Journals (Sweden)

Anthony J Bellantuono

Full Text Available The acclimatization capacity of corals is a critical consideration in the persistence of coral reefs under stresses imposed by global climate change. The stress history of corals plays a role in subsequent response to heat stress, but the transcriptomic changes associated with these plastic changes have not been previously explored. In order to identify host transcriptomic changes associated with acquired thermal tolerance in the scleractinian coral Acropora millepora, corals preconditioned to a sub-lethal temperature of 3°C below bleaching threshold temperature were compared to both non-preconditioned corals and untreated controls using a cDNA microarray platform. After eight days of hyperthermal challenge, conditions under which non-preconditioned corals bleached and preconditioned corals (thermal-tolerant maintained Symbiodinium density, a clear differentiation in the transcriptional profiles was revealed among the condition examined. Among these changes, nine differentially expressed genes separated preconditioned corals from non-preconditioned corals, with 42 genes differentially expressed between control and preconditioned treatments, and 70 genes between non-preconditioned corals and controls. Differentially expressed genes included components of an apoptotic signaling cascade, which suggest the inhibition of apoptosis in preconditioned corals. Additionally, lectins and genes involved in response to oxidative stress were also detected. One dominant pattern was the apparent tuning of gene expression observed between preconditioned and non-preconditioned treatments; that is, differences in expression magnitude were more apparent than differences in the identity of genes differentially expressed. Our work revealed a transcriptomic signature underlying the tolerance associated with coral thermal history, and suggests that understanding the molecular mechanisms behind physiological acclimatization would be critical for the modeling of reefs

Constraining Cosmic Dawn and Cosmological Reionization via the global redshifted 21-cm signal

Science.gov (United States)

Singh, Saurabh

2018-01-01

The formation of first stars and consequent thermal evolution in baryons during Cosmic Dawn and the Epoch of Reionization (EoR) is poorly constrained. The 21-cm line transition of neutral hydrogen is one of the richest probes of the astrophysics during this era. The signal has the potential to reveal the nature and timing of the emergence of first stars, first light, and the consequent evolution in thermal and ionization state of the baryons.The detection of the global redshifted 21-cm signal, which represents the mean thermal history of the gas, is challenging since it is extremely faint and seen through orders of magnitude stronger contributions from Galactic and extragalactic foregrounds. Man-made terrestrial Radio Frequency Interference (RFI) and the exacting tolerances required on instrument systematics make the detection even more daunting.The design considerations for a precision spectral radiometer are first listed, and a comparison is made of different radiometer configurations, including short and zero baseline interferometers along with methods to enhance the response. We discuss the relative merits of different methods.We then describe SARAS 2, a spectral radiometer custom-designed for precision measurement of the global 21-cm signal. SARAS 2 has been designed to have a system transfer function and internal systematics – both multiplicative and additive – to be spectrally smooth so as to allow a separation of foregrounds and systematics from plausible and predicted global cosmological 21-cm signals. The algorithms for calibration and RFI mitigation are carefully developed so that they do not introduce spectral features that may confuse the detection of the 21-cm signal.We present the outcomes for cosmology from analysis of 60 hr observing with the radiometer deployed at the Timbaktu Collective in Southern India. The detailed analysis of the data reveals an RMS noise level of 11 mK, without being limited by systematic structures. The likelihood

High Resolution Viscosity Measurement by Thermal Noise Detection

Directory of Open Access Journals (Sweden)

Felipe Aguilar Sandoval

2015-11-01

Full Text Available An interferometric method is implemented in order to accurately assess the thermal fluctuations of a micro-cantilever sensor in liquid environments. The power spectrum density (PSD of thermal fluctuations together with Sader’s model of the cantilever allow for the indirect measurement of the liquid viscosity with good accuracy. The good quality of the deflection signal and the characteristic low noise of the instrument allow for the detection and corrections of drawbacks due to both the cantilever shape irregularities and the uncertainties on the position of the laser spot at the fluctuating end of the cantilever. Variation of viscosity below 0.03 mPa·s was detected with the alternative to achieve measurements with a volume as low as 50 µL.

SETI - A preliminary search for narrowband signals at microwave frequencies

Science.gov (United States)

Cuzzi, J. N.; Clark, T. A.; Tarter, J. C.; Black, D. C.

1977-01-01

In the search for intelligent signals of extraterrestrial origin, certain forms of signals merit immediate and special attention. Extremely narrowband signals of spectral width similar to our own television transmissions are most favored energetically and least likely to be confused with natural celestial emission. A search of selected stars has been initiated using observational and data processing techniques optimized for the detection of such signals. These techniques allow simultaneous observation of 10 to the 5th to 10 to the 6th channels within the observed spectral range. About two hundred nearby (within 80 LY) solar type stars have been observed at frequencies near the main microwave transitions of the hydroxyl radical. In addition, several molecular (hydroxyl) masers and other non-thermal sources have been observed in this way in order to uncover any possible fine spectral structure of natural origin and to investigate the potential of such an instrument for radioastronomy.

Progress in thermal comfort research over the last twenty years.

Science.gov (United States)

de Dear, R J; Akimoto, T; Arens, E A; Brager, G; Candido, C; Cheong, K W D; Li, B; Nishihara, N; Sekhar, S C; Tanabe, S; Toftum, J; Zhang, H; Zhu, Y

2013-12-01

Climate change and the urgency of decarbonizing the built environment are driving technological innovation in the way we deliver thermal comfort to occupants. These changes, in turn, seem to be setting the directions for contemporary thermal comfort research. This article presents a literature review of major changes, developments, and trends in the field of thermal comfort research over the last 20 years. One of the main paradigm shift was the fundamental conceptual reorientation that has taken place in thermal comfort thinking over the last 20 years; a shift away from the physically based determinism of Fanger's comfort model toward the mainstream and acceptance of the adaptive comfort model. Another noticeable shift has been from the undesirable toward the desirable qualities of air movement. Additionally, sophisticated models covering the physics and physiology of the human body were developed, driven by the continuous challenge to model thermal comfort at the same anatomical resolution and to combine these localized signals into a coherent, global thermal perception. Finally, the demand for ever increasing building energy efficiency is pushing technological innovation in the way we deliver comfortable indoor environments. These trends, in turn, continue setting the directions for contemporary thermal comfort research for the next decades. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Numerical modeling of thermal fatigue cracks from the viewpoint of eddy current testing

International Nuclear Information System (INIS)

Yusa, Noritaka; Hashizume, Hidetoshi; Virkkunen, Iikka; Kemppainen, Mika

2012-01-01

This study discusses a suitable numerical modeling of a thermal fatigue crack from the viewpoint of eddy current testing. Five artificial thermal fatigue cracks, introduced into type 304L austenitic stainless steel plates with a thickness of 25 mm, are prepared; and eddy current inspections are carried out to gather signals using an absolute type pancake probe and a differential type plus point probe. Finite element simulations are then carried out to evaluate a proper numerical model of the thermal fatigue cracks. In the finite element simulations, the thermal fatigue cracks are modeled as a semi-elliptic planar region on the basis of the results of the destructive tests. The width and internal conductivity are evaluated by the simulations. The results of the simulations reveal that the thermal fatigue cracks are regarded as almost nonconductive when the internal conductivity is assumed to be uniform inside. (author)

Long Range Active Detection of HEU Based on Thermal Neutron Multiplication

Energy Technology Data Exchange (ETDEWEB)

Forman L.; Dioszegi I.; Salwen, C.; and Vanier, P.E.

2010-05-24

We report on the results of measurements of proton irradiation on a series of targets at Brookhaven National Laboratory’s (BNL) Alternate Gradient Synchrotron Facility (AGS), in collaboration with LANL and SNL. We examined the prompt radiation environment in the tunnel for the DTRA-sponsored series (E 972), which investigated the penetration of air and subsequent target interaction of 4 GeV proton pulses. Measurements were made by means of an organic scintillator with a 500 MHz bandwidth system. We found that irradiation of a depleted uranium (DU) target resulted in a large gamma-ray signal in the 100-500 µsec time region after the proton flash when the DU was surrounded by polyethylene, but little signal was generated if it was surrounded by boron-loaded polyethylene. Subsequent Monte Carlo (MCNPX) calculations indicated that the source of the signal was consistent with thermal neutron capture in DU. The MCNPX calculations also indicated that if one were to perform the same experiment with a highly enriched uranium (HEU) target there would be a distinctive fast neutron yield in this 100-500 µsec time region from thermal neutron-induced fission. The fast neutrons can be recorded by the same direct current system and differentiated from gamma ray pulses in organic scintillator by pulse shape discrimination.

Design and evaluation of a flow-to-frequency converter circuit with thermal feedback

International Nuclear Information System (INIS)

Pawlowski, Eligiusz

2017-01-01

A novel thermal flow sensor with a frequency output is presented. The sensor provides a pulse-train output whose frequency is related to the fluid flow rate around a self-heating thermistor. The integrating properties of the temperature sensor have been used, which allowed for realization of the pulse frequency modulator with a thermal feedback loop, stabilizing the temperature of the sensor placed in the flowing medium. The system assures a balance of the amount of heat supplied in the impulses to the sensor and the heat given up by the sensor in a continuous way to the flowing medium. Therefore the frequency of output pulse-train is proportional to the medium flow velocity around the sensor. The special feature of the presented solution is the total integration of the thermal sensor with the measurement signal conditioning system. i.e. the sensor and conditioning system are not separate elements of the measurement circuit, but constitute a whole in the form of a thermal heat-balance mode flow-to-frequency converter. The frequency signal from the converter may be directly connected to the microprocessor digital input, which with use of the standard built-in counters may convert the frequency into a numerical value of high precision. The sensor has been experimentally characterized as a function of the average flow velocity of air at room temperature. (paper)

Thermal fatigue cracking in T-fittings of feed water systems

International Nuclear Information System (INIS)

Oesterberg, J.

1983-03-01

The existence of thermal fatigue cracks can be determined by ultrasonic methods. The depth of the cracks will be of importance for evaluation of the seriousness of the situation. Currently, no method is available for determining depth of cracks without cutting and grinding. Methods for gaining information of crack depth have been discussed with leading European materials testing institutes. More elaborate ultrasonic methods have been tested with negative results. On testing signals from crack corners flood possible signals from the crack tips. At present no reliable technique based on ultrasonics exist (in Europe, that will give information of crack depth.(P.Aa.)

Parametric Amplification Protocol for Frequency-Modulated Magnetic Resonance Force Microscopy Signals

Science.gov (United States)

Harrell, Lee; Moore, Eric; Lee, Sanggap; Hickman, Steven; Marohn, John

2011-03-01

We present data and theoretical signal and noise calculations for a protocol using parametric amplification to evade the inherent tradeoff between signal and detector frequency noise in force-gradient magnetic resonance force microscopy signals, which are manifested as a modulated frequency shift of a high- Q microcantilever. Substrate-induced frequency noise has a 1 / f frequency dependence, while detector noise exhibits an f2 dependence on modulation frequency f . Modulation of sample spins at a frequency that minimizes these two contributions typically results in a surface frequency noise power an order of magnitude or more above the thermal limit and may prove incompatible with sample spin relaxation times as well. We show that the frequency modulated force-gradient signal can be used to excite the fundamental resonant mode of the cantilever, resulting in an audio frequency amplitude signal that is readily detected with a low-noise fiber optic interferometer. This technique allows us to modulate the force-gradient signal at a sufficiently high frequency so that substrate-induced frequency noise is evaded without subjecting the signal to the normal f2 detector noise of conventional demodulation.

Seismic monitoring of effusive-explosive activity and large lava dome collapses during 2013-2015 at Volcán de Colima, Mexico

Science.gov (United States)

Arámbula-Mendoza, Raúl; Reyes-Dávila, Gabriel; Vargas-Bracamontes Dulce, M.; González-Amezcua, Miguel; Navarro-Ochoa, Carlos; Martínez-Fierros, Alejandro; Ramírez-Vázquez, Ariel

2018-02-01

Volcán de Colima, the most active volcano in Mexico, started a new eruptive cycle in January 2013. Since this date, the volcano has presented effusive and explosive activity. The beginning of the cycle was marked by a moderate Vulcanian explosion which had hyperbolical behavior in its precursory seismicity, possibly related to a shallow rupture process. Then, during the whole eruptive stage, the effusive activity was accompanied by low to moderate explosions. The explosions had energies mainly of 106 joules and were located between 0 and 1600 m below the crater, whereas the locations of tremor sources were found to be deeper, reaching up to 3800 m beneath the crater. Very-long-period signals (VLPs) have been observed with Vulcanian explosions that produce pyroclastic flows. A few number of volcano-tectonic events (VTs) were recognized during the studied period (2013-2015), indicating that the volcano is an open system. This was particularly evidenced in July 2015, when a new batch of magma rose rapidly without large precursors, only an accelerated increase in the number of rockfalls and associated RSEM. This event generated two large lava dome collapses with several pulses of material and pyroclastic flows that travelled up to 10.3 km from the summit. The seismic monitoring of Volcán de Colima is currently the only tool in real-time employed to assess the state of the volcanic activity. It is thus necessary to integrate new seismic methods as well as other geophysical monitoring techniques able to detect precursory signals of an impending hazardous event.

Simultaneous measurement of thermal conductivity and heat capacity of bulk and thin film materials using frequency-dependent transient thermoreflectance method.

Science.gov (United States)

Liu, Jun; Zhu, Jie; Tian, Miao; Gu, Xiaokun; Schmidt, Aaron; Yang, Ronggui

2013-03-01

The increasing interest in the extraordinary thermal properties of nanostructures has led to the development of various measurement techniques. Transient thermoreflectance method has emerged as a reliable measurement technique for thermal conductivity of thin films. In this method, the determination of thermal conductivity usually relies much on the accuracy of heat capacity input. For new nanoscale materials with unknown or less-understood thermal properties, it is either questionable to assume bulk heat capacity for nanostructures or difficult to obtain the bulk form of those materials for a conventional heat capacity measurement. In this paper, we describe a technique for simultaneous measurement of thermal conductivity κ and volumetric heat capacity C of both bulk and thin film materials using frequency-dependent time-domain thermoreflectance (TDTR) signals. The heat transfer model is analyzed first to find how different combinations of κ and C determine the frequency-dependent TDTR signals. Simultaneous measurement of thermal conductivity and volumetric heat capacity is then demonstrated with bulk Si and thin film SiO2 samples using frequency-dependent TDTR measurement. This method is further testified by measuring both thermal conductivity and volumetric heat capacity of novel hybrid organic-inorganic thin films fabricated using the atomic∕molecular layer deposition. Simultaneous measurement of thermal conductivity and heat capacity can significantly shorten the development∕discovery cycle of novel materials.

Electrical and thermal characterization of single and multi-finger InP DHBTs

DEFF Research Database (Denmark)

Midili, Virginio; Nodjiadjim, V.; Johansen, Tom Keinicke

2015-01-01

This paper presents the characterization of single and multi-finger Indium Phosphide Double Heterojunction Bipolar transistors (InP DHBTs). It is used as the starting point for technology optimization. Safe Operating Area (SOA) and small signal AC parameters are investigated along with thermal ch...

Implication of conjugate faulting in the earthquake brewing and originating process

Energy Technology Data Exchange (ETDEWEB)

Jones, L.M. (Massachusetts Inst. of Tech., Cambridge); Deng, Q.; Jiang, P.

1980-03-01

The earthquake sequence, precursory and geologo-structural background of the Haicheng, Tangshan, Songpan-Pingwu earthquakes are discussed in this article. All of these earthquakes occurred in a seismic zone controlled by the main boundary faults of an intraplate fault block. However, the fault plane of a main earthquake does not consist of the same faults, but is rather a related secondary fault. They formed altogether a conjugate shearing rupture zone under the action of a regional tectonic stress field. As to the earthquake sequence, the foreshocks and aftershocks might occur on the conjugate fault planes within an epicentral region rather than be limited to the fault plane of a main earthquake, such as the distribution of foreshocks and aftershocks of the Haicheng earthquake. The characteristics of the long-, medium-, and imminent-term earthquake precursory anomalies of the three mentioned earthquakes, especially the character of well-studies anomaly phenomena in electrical resistivity, radon emission, groundwater and animal behavior, have been investigated. The studies of these earthquake precursors show that they were distributed in an area rather more extensive than the epicentral region. Some fault zones in the conjugate fault network usually appeared as distributed belts or concentrated zones of earthquake precursory anomalies, and can be traced in the medium-long term precursory field, but seem more distinct in the short-imminent term precursory anomalous field. These characteristics can be explained by the rupture and sliding originating along the conjugate shear network and the concentration of stress in the regional stress field.

Adaptive phase estimation with squeezed thermal light

DEFF Research Database (Denmark)

Berni, A. A.; Madsen, Lars Skovgaard; Lassen, Mikael Østergaard

2013-01-01

Summary form only given. The use of quantum states of light in optical interferometry improves the precision in the estimation of a phase shift, paving the way for applications in quantum metrology, computation and cryptography. Sub-shot noise phase sensing can for example be achieved by injecting...... investigate the performances of such protocol under the realistic assumption of thermalization of the probe state. Indeed, adaptive phase estimation schemes with squeezed states and Bayesian processing of homodyne data have been shown to be asymptotically optimal in the pure case, thus approaching the quantum...... Cramér-Rao bound. In our protocol we take advantage of the enhanced sensitivity of homodyne detection in proximity of the optimal phase which maximizes the homodyne Fisher information. A squeezed thermal probe state (signal) undergoes an unknown phase shift. The first estimation step involves...

The micro thermal analysis of polymers

International Nuclear Information System (INIS)

Grandy, David Brian

2002-01-01

of -50 deg C, or lower, to above 250 deg C. The adhesion-dependent pull-off force signal is found to be far more sensitive to local variations in mechanical properties than the local compliance-dependent indentation force signal. Finally, the principle of using a high resolution micro-fabricated thermal probe in pulsed force mode is established. PFM-AFM images acquired with the probe at room temperature and 150 deg C are presented. A similar transformation is evident in the pull-off force image of the PS-PMMA blend as is obtained by changing the temperature of the whole sample while using an inert probe. (author)

Mechanism for thermal relic dark matter of strongly interacting massive particles.

Science.gov (United States)

Hochberg, Yonit; Kuflik, Eric; Volansky, Tomer; Wacker, Jay G

2014-10-24

We present a new paradigm for achieving thermal relic dark matter. The mechanism arises when a nearly secluded dark sector is thermalized with the standard model after reheating. The freeze-out process is a number-changing 3→2 annihilation of strongly interacting massive particles (SIMPs) in the dark sector, and points to sub-GeV dark matter. The couplings to the visible sector, necessary for maintaining thermal equilibrium with the standard model, imply measurable signals that will allow coverage of a significant part of the parameter space with future indirect- and direct-detection experiments and via direct production of dark matter at colliders. Moreover, 3→2 annihilations typically predict sizable 2→2 self-interactions which naturally address the "core versus cusp" and "too-big-to-fail" small-scale structure formation problems.

Multiple-failure signal validation in nuclear power plants using artificial neural networks

International Nuclear Information System (INIS)

Fantoni, P.F.; Mazzola, A.

1996-01-01

The possibility of using a neural network to validate process signals during normal and abnormal plant conditions is explored. In boiling water reactor plants, signal validation is used to generate reliable thermal limits calculation and to supply reliable inputs to other computerized systems that support the operator during accident scenarios. The way that autoassociative neural networks can promptly detect faulty process signal measurements and produce a best estimate of the actual process values even in multifailure situations is shown. A method was developed to train the network for multiple sensor-failure detection, based on a random failure simulation algorithm. Noise was artificially added to the input to evaluate the network's ability to respond in a very low signal-to-noise ratio environment. Training and test data sets were simulated by the real-time transient simulator code APROS

Bone assessment via thermal photoacoustic measurements

Science.gov (United States)

Feng, Ting; Kozloff, Kenneth M.; Hsiao, Yi-Sing; Tian, Chao; Perosky, Joseph; Du, Sidan; Yuan, Jie; Deng, Cheri X.; Wang, Xueding

2015-03-01

The feasibility of an innovative biomedical diagnostic technique, thermal photoacoustic (TPA) measurement, for nonionizing and non-invasive assessment of bone health is investigated. Unlike conventional photoacoustic PA methods which are mostly focused on the measurement of absolute signal intensity, TPA targets the change in PA signal intensity as a function of the sample temperature, i.e. the temperature dependent Grueneisen parameter which is closely relevant to the chemical and molecular properties in the sample. Based on the differentiation measurement, the results from TPA technique is less susceptible to the variations associated with sample and system, and could be quantified with improved accurately. Due to the fact that the PA signal intensity from organic components such as blood changes faster than that from non-organic mineral under the same modulation of temperature, TPA measurement is able to objectively evaluate bone mineral density (BMD) and its loss as a result of osteoporosis. In an experiment on well established rat models of bone loss and preservation, PA measurements of rat tibia bones were conducted over a temperature range from 370 C to 440 C. The slope of PA signal intensity verses temperature was quantified for each specimen. The comparison among three groups of specimens with different BMD shows that bones with lower BMD have higher slopes, demonstrating the potential of the proposed TPA technique in future clinical management of osteoporosis.

Thermal transistor utilizing gas-liquid transition

KAUST Repository

Komatsu, Teruhisa S.

2011-01-25

We propose a simple thermal transistor, a device to control heat current. In order to effectively change the current, we utilize the gas-liquid transition of the heat-conducting medium (fluid) because the gas region can act as a good thermal insulator. The three terminals of the transistor are located at both ends and the center of the system, and are put into contact with distinct heat baths. The key idea is a special arrangement of the three terminals. The temperature at one end (the gate temperature) is used as an input signal to control the heat current between the center (source, hot) and another end (drain, cold). Simulating the nanoscale systems of this transistor, control of heat current is demonstrated. The heat current is effectively cut off when the gate temperature is cold and it flows normally when it is hot. By using an extended version of this transistor, we also simulate a primitive application for an inverter. © 2011 American Physical Society.

On-line monitoring on thermal shock damage of ceramics using acoustic emission

International Nuclear Information System (INIS)

Lee, Jin Kyung; Lee, Joon Hyun; Song, Sang Hun

1999-01-01

The objective of this paper is to investigate the degree of the thermal shock damage on alumina ceramic using acoustic emission technique. For this purpose, alumina ceramic specimen was heated in the elastic furnace and then was quenched into the water tank. When the specimen was quenched into water tank, a lot of micro-cracks were generated on the surface of specimen due to the thermal shock damage. In this study, acoustic emission technique was used to evaluate the elastic waves generated by the crack initiation and propagation on the surface of specimen. It was found that when the micro-crack was initiated on the surface of specimen, AE signals were the higher in amplitude than those of bubbling effect and crack propagation. A lot of AE events were generated at the first thermal shock, the number of AE events decreased gradually as the thermal shock cycle increased.

Is the Experience of Thermal Pain Genetics Dependent?

Directory of Open Access Journals (Sweden)

Emilia Horjales-Araujo

2015-01-01

Full Text Available It is suggested that genetic variations explain a significant portion of the variability in pain perception; therefore, increased understanding of pain-related genetic influences may identify new targets for therapies and treatments. The relative contribution of the different genes to the variance in clinical and experimental pain responses remains unknown. It is suggested that the genetic contributions to pain perception vary across pain modalities. For example, it has been suggested that more than 60% of the variance in cold pressor responses can be explained by genetic factors; in comparison, only 26% of the variance in heat pain responses is explained by these variations. Thus, the selection of pain model might markedly influence the magnitude of the association between the pain phenotype and genetic variability. Thermal pain sensation is complex with multiple molecular and cellular mechanisms operating alone and in combination within the peripheral and central nervous system. It is thus highly probable that the thermal pain experience is affected by genetic variants in one or more of the pathways involved in the thermal pain signaling. This review aims to present and discuss some of the genetic variations that have previously been associated with different experimental thermal pain models.

Target acquisition performance : Effects of target aspect angle, dynamic imaging and signal processing

NARCIS (Netherlands)

Beintema, J.A.; Bijl, P.; Hogervorst, M.A.; Dijk, J.

2008-01-01

In an extensive Target Acquisition (TA) performance study, we recorded static and dynamic imagery of a set of military and civilian two-handheld objects at a range of distances and aspect angles with an under-sampled uncooled thermal imager. Next, we applied signal processing techniques including

Extraction of thermal Green's function using diffuse fields: a passive approach applied to thermography

Science.gov (United States)

Capriotti, Margherita; Sternini, Simone; Lanza di Scalea, Francesco; Mariani, Stefano

2016-04-01

In the field of non-destructive evaluation, defect detection and visualization can be performed exploiting different techniques relying either on an active or a passive approach. In the following paper the passive technique is investigated due to its numerous advantages and its application to thermography is explored. In previous works, it has been shown that it is possible to reconstruct the Green's function between any pair of points of a sensing grid by using noise originated from diffuse fields in acoustic environments. The extraction of the Green's function can be achieved by cross-correlating these random recorded waves. Averaging, filtering and length of the measured signals play an important role in this process. This concept is here applied in an NDE perspective utilizing thermal fluctuations present on structural materials. Temperature variations interacting with thermal properties of the specimen allow for the characterization of the material and its health condition. The exploitation of the thermographic image resolution as a dense grid of sensors constitutes the basic idea underlying passive thermography. Particular attention will be placed on the creation of a proper diffuse thermal field, studying the number, placement and excitation signal of heat sources. Results from numerical simulations will be presented to assess the capabilities and performances of the passive thermal technique devoted to defect detection and imaging of structural components.

Investigations of anomalous gravity signals prior to 71 large earthquakes based on a 4-years long superconducting gravimeter records

Directory of Open Access Journals (Sweden)

Dijin Wang

2017-09-01

Full Text Available Using continuous 1-Hz sampling time-series recorded by a SG (superconducting gravimeter at Hsinchu station, Taiwan of China, we investigate the anomalous gravity signals prior to 71 large earthquakes with moment magnitude larger than 7.0 (Mw7.0 occurred between 1 Jan 2008 and 31 Dec 2011. We firstly evaluate the noise level of the SG records at Hsinchu (HS station in microseismic bands from 0.05 Hz to 0.1 Hz by computing the PSD (power spectral density of seismically quiet days selected based on the RMS of records. Based on the analysis of the noise level and the spectral features of the seismically quiet SG records at HS station, we detect AGSs (anomalous gravity signals prior to large earthquakes. We apply HHT (Hilbert-Huang transformation to establish the TFEP (time-frequency-energy paradigms and MS (marginal spectra of the SG data before the large earthquakes, and the characteristics of TFEP and MS of the SGs data during the typhoon event are also analyzed. By comparing the spectral characteristics of the SGs data during seismically quiet period, three types of AGSs are found; and the occurrence rate of AGSs before 71 earthquakes is given in terms of the cases with different epicenter distance and different focal depth. The statistical results show that 56.3% of all the examined large earthquakes were preceded by AGSs; and if we constrain the epicenter distance to be smaller than 3500 km and focal depth less than 300 km, 75.3% of the examined large earthquakes can be associated with the AGSs. Especially, we note that for all the large earthquakes occurred in the Eurasian plate in recent four years, the precursory AGSs can always be found in the SG data recorded at HS station. Our investigations suggest that the AGSs prior to large earthquakes may be related to focal depth, epicentre distance and location.

A non-contact, thermal noise based method for the calibration of lateral deflection sensitivity in atomic force microscopy

International Nuclear Information System (INIS)

Mullin, Nic; Hobbs, Jamie K.

2014-01-01

Calibration of lateral forces and displacements has been a long standing problem in lateral force microscopies. Recently, it was shown by Wagner et al. that the thermal noise spectrum of the first torsional mode may be used to calibrate the deflection sensitivity of the detector. This method is quick, non-destructive and may be performed in situ in air or liquid. Here we make a full quantitative comparison of the lateral inverse optical lever sensitivity obtained by the lateral thermal noise method and the shape independent method developed by Anderson et al. We find that the thermal method provides accurate results for a wide variety of rectangular cantilevers, provided that the geometry of the cantilever is suitable for torsional stiffness calibration by the torsional Sader method, in-plane bending of the cantilever may be eliminated or accounted for and that any scaling of the lateral deflection signal between the measurement of the lateral thermal noise and the measurement of the lateral deflection is eliminated or corrected for. We also demonstrate that the thermal method may be used to characterize the linearity of the detector signal as a function of position, and find a deviation of less than 8% for the instrument used

Time of correlation of low-frequency fluctuations in the regional laser Doppler flow signal from human skin

Science.gov (United States)

Folgosi-Correa, M. S.; Nogueira, G. E. C.

2012-06-01

The laser Doppler flowmetry allows the non-invasive assessment of the skin perfusion in real-time, being an attractive technique to study the human microcirculation in clinical settings. Low-frequency oscillations in the laser Doppler blood flow signal from the skin have been related to the endothelial, endothelial-metabolic, neurogenic and myogenic mechanisms of microvascular flow control, in the range 0.005-0.0095 Hz, 0.0095-0.021 Hz, 0.021-0.052 Hz and 0.052- 0.145 Hz respectively. The mean Amplitude (A) of the periodic fluctuations in the laser Doppler blood flow signal, in each frequency range, derived from the respective wavelet-transformed coefficients, has been used to assess the function and dysfunctions of each mechanism of flow control. Known sources of flow signal variances include spatial and temporal variability, diminishing the discriminatory capability of the technique. Here a new time domain method of analysis is proposed, based on the Time of Correlation (TC) of flow fluctuations between two adjacent sites. Registers of blood flow from two adjacent regions, for skin temperature at 32 0C (basal) and thermally stimulated (42 0C) of volar forearms from 20 healthy volunteers were collected and analyzed. The results obtained revealed high time of correlation between two adjacent regions when thermally stimulated, for signals in the endothelial, endothelial-metabolic, neurogenic and myogenic frequency ranges. Experimental data also indicate lower variability for TC when compared to A, when thermally stimulated, suggesting a new promising parameter for assessment of the microvascular flow control.

Prediction of Geomechanical Properties from Thermal Conductivity of Low-Permeable Reservoirs

Science.gov (United States)

Chekhonin, Evgeny; Popov, Evgeny; Popov, Yury; Spasennykh, Mikhail; Ovcharenko, Yury; Zhukov, Vladislav; Martemyanov, Andrey

2016-04-01

A key to assessing a sedimentary basin's hydrocarbon prospect is correct reconstruction of thermal and structural evolution. It is impossible without adequate theory and reliable input data including among other factors thermal and geomechanical rock properties. Both these factors are also important in geothermal reservoirs evaluation and carbon sequestration problem. Geomechanical parameters are usually estimated from sonic logging and rare laboratory measurements, but sometimes it is not possible technically (low quality of the acoustic signal, inappropriate borehole and mud conditions, low core quality). No wonder that there are attempts to correlate the thermal and geomechanical properties of rock, but no one before did it with large amount of high quality thermal conductivity data. Coupling results of sonic logging and non-destructive non-contact thermal core logging opens wide perspectives for studying a relationship between the thermal and geomechanical properties. More than 150 m of full size cores have been measured at core storage with optical scanning technique. Along with results of sonic logging performed with Sonic Scanner in different wells drilled in low permeable formations in West Siberia (Russia) it provided us with unique data set. It was established a strong correlation between components of thermal conductivity (measured perpendicular and parallel to bedding) and compressional and shear acoustic velocities in Bazhen formation. As a result, prediction of geomechanical properties via thermal conductivity data becomes possible, corresponding results was demonstrated. The work was supported by the Russian Ministry of Education and Science, project No. RFMEFI58114X0008.

Dynamic thermal environment and thermal comfort.

Science.gov (United States)

Zhu, Y; Ouyang, Q; Cao, B; Zhou, X; Yu, J

2016-02-01

Research has shown that a stable thermal environment with tight temperature control cannot bring occupants more thermal comfort. Instead, such an environment will incur higher energy costs and produce greater CO2 emissions. Furthermore, this may lead to the degeneration of occupants' inherent ability to combat thermal stress, thereby weakening thermal adaptability. Measured data from many field investigations have shown that the human body has a higher acceptance to the thermal environment in free-running buildings than to that in air-conditioned buildings with similar average parameters. In naturally ventilated environments, occupants have reported superior thermal comfort votes and much greater thermal comfort temperature ranges compared to air-conditioned environments. This phenomenon is an integral part of the adaptive thermal comfort model. In addition, climate chamber experiments have proven that people prefer natural wind to mechanical wind in warm conditions; in other words, dynamic airflow can provide a superior cooling effect. However, these findings also indicate that significant questions related to thermal comfort remain unanswered. For example, what is the cause of these phenomena? How we can build a comfortable and healthy indoor environment for human beings? This article summarizes a series of research achievements in recent decades, tries to address some of these unanswered questions, and attempts to summarize certain problems for future research. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Multi-Channel RF System for MRI-Guided Transurethral Ultrasound Thermal Therapy

Science.gov (United States)

Yak, Nicolas; Asselin, Matthew; Chopra, Rajiv; Bronskill, Michael

2009-04-01

MRI-guided transurethral ultrasound thermal therapy is an approach to treating localized prostate cancer which targets precise deposition of thermal energy within a confined region of the gland. This treatment requires a system incorporating a heating applicator with multiple planar ultrasound transducers and associated RF electronics to control individual elements independently in order to achieve accurate 3D treatment. We report the design, construction, and characterization of a prototype multi-channel system capable of controlling 16 independent RF signals for a 16-element heating applicator. The main components are a control computer, microcontroller, and a 16-channel signal generator with 16 amplifiers, each incorporating a low-pass filter and transmitted/reflected power detection circuit. Each channel can deliver from 0.5 to 10 W of electrical power and good linearity from 3 to 12 MHz. Harmonic RF signals near the Larmor frequency of a 1.5 T MRI were measured to be below -30 dBm and heating experiments within the 1.5 T MR system showed no significant decrease in SNR of the temperature images. The frequency and power for all 16 channels could be changed in less than 250 ms, which was sufficiently rapid for proper performance of the control algorithms. A common backplane design was chosen which enabled an inexpensive, modular approach for each channel resulting in an overall system with minimal footprint.

DESIGN OF AN EDUCATIONAL SIMULATION PROGRAM USING DIGITAL VIDEO PROCESSING TO DETERMINE THE THERMAL EXPANSION OF MATERIALS

Directory of Open Access Journals (Sweden)

V. Gökhan BÖCEKÇİ

2013-01-01

Full Text Available The present report describes the realization of an educational simulation program to determine the amount of linear thermal expansion in experimental materials. An interferogram signal derived from an interferometric measurement system was modeled as a video signal in a computer environment. A simulation program was designed from the model signal in order to detect the amount of expansion in materials. The simulation program determined the amount of to heat by detecting the number of fringes in interferogram video signals of the material. This simulation program facilitated experimental studies n academic institutions which are deprived of interferometric measurement systems.

Neutrino signals from gravitino dark matter with broken R-parity

Energy Technology Data Exchange (ETDEWEB)

Grefe, M.

2008-12-15

The gravitino is a promising supersymmetric dark matter candidate, even without strict R-parity conservation. In fact, with some small R-parity violation, gravitinos are sufficiently long-lived to constitute the dark matter of the universe, while the resulting cosmological scenario is consistent with primordial nucleosynthesis and the high reheating temperature needed for thermal leptogenesis. Furthermore, in this scenario the gravitino is unstable and might thus be accessible by indirect detection via its decay products. We compute in this thesis the partial decay widths for the gravitino in models with bilinear R-parity breaking. In addition, we determine the neutrino signal from astrophysical gravitino dark matter decays. Finally, we discuss the feasibility of detecting these neutrino signals in present and future neutrino experiments, and conclude that it will be a challenging task. Albeit, if detected, this distinctive signal might bring considerable support to the scenario of decaying gravitino dark matter. (orig.)

Spectral responses of gravel beaches to tidal signals

Science.gov (United States)

Geng, Xiaolong; Boufadel, Michel C.

2017-01-01

Tides have been recognized as a major driving forcing affecting coastal aquifer system, and deterministic modeling has been very effective in elucidating mechanisms caused by tides. However, such modeling does not lend itself to capture embedded information in the signal, and rather focuses on the primary processes. Here, using yearlong data sets measured at beaches in Alaska Prince William Sound, we performed spectral and correlation analyses to identify temporal behavior of pore-water pressure, temperature and salinity. We found that the response of the beach system was characterized by fluctuations of embedded diurnal, semidiurnal, terdiurnal and quarterdiurnal tidal components. Hydrodynamic dispersion of salinity and temperature, and the thermal conductivity greatly affected pore water signals. Spectral analyses revealed a faster dissipation of the semi-diurnal component with respect to the diurnal components. Correlation functions showed that salinity had a relatively short memory of the tidal signal when inland freshwater recharge was large. In contrast, the signature of the tidal signal on pore-water temperature persisted for longer times, up to a week. We also found that heterogeneity greatly affected beach response. The response varied from a simple linear mapping in the frequency domain to complete modulation and masking of the input frequencies.

Heat Transfer Analysis and Modification of Thermal Probe for Gas-Solid Measurement

Directory of Open Access Journals (Sweden)

Hong Zhang

2016-01-01

Full Text Available The presented work aims to measure the gas-solid two-phase mass flow-rate in pneumatic conveyor, and a novel modified thermal probe is applied. A new analysis of the local heat transfer coefficients of thermal probe is presented, while traditional investigations focus on global coefficients. Thermal simulations are performed in Fluent 6.2 and temperature distributions of the probe are presented. The results indicate that the probe has obviously stable and unstable heat transfer areas. Based on understanding of probe characteristics, a modified probe structure is designed, which makes the probe output signal more stable and widens the measuring range. The experiments are carried out in a special designed laboratory scale pneumatic conveyor, and the modified probe shows an unambiguous improvement of the performance compared with the traditional one.

Thermo-optically tuned photonic resonators with concurrent electrical connection and thermal isolation

Science.gov (United States)

Lentine, Anthony L.; Kekatpure, Rohan Deodatta; Zortman, William A.; Savignon, Daniel J.

2016-06-14

A photonic resonator system is designed to use thermal tuning to adjust the resonant wavelength of each resonator in the system, with a separate tuning circuit associated with each resonator so that individual adjustments may be made. The common electrical ground connection between the tuning circuits is particularly formed to provide thermal isolation between adjacent resonators by including a capacitor along each return path to ground, where the presence of the capacitor's dielectric material provides the thermal isolation. The use of capacitively coupling necessarily requires the use of an AC current as an input to the heater element (conductor/resistor) of each resonator, where the RMS value of the AC signal is indicative of the amount of heat that is generated along the element and the degree of wavelength tuning that is obtained.

Thermally Optimized Paradigm of Thermal Management (TOP-M)

Science.gov (United States)

2017-07-18

19b. TELEPHONE NUMBER (Include area code) 18-07-2017 Final Technical Jul 2015 - Jul 2017 NICOP - Thermally Optimized Paradigm of Thermal Management ...The main goal of this research was to present a New Thermal Management Approach, which combines thermally aware Very/Ultra Large Scale Integration...SPAD) image sensors were used to demonstrate the new thermal management approach. Thermal management , integrated temperature sensors, Vt extractor

Detection of impact damage on thermal protection systems using thin-film piezoelectric sensors for integrated structural health monitoring

Science.gov (United States)

Na, Jeong K.; Kuhr, Samuel J.; Jata, Kumar V.

2008-03-01

Thermal Protection Systems (TPS) can be subjected to impact damage during flight and/or during ground maintenance and/or repair. AFRL/RXLP is developing a reliable and robust on-board sensing/monitoring capability for next generation thermal protection systems to detect and assess impact damage. This study was focused on two classes of metallic thermal protection tiles to determine threshold for impact damage and develop sensing capability of the impacts. Sensors made of PVDF piezoelectric film were employed and tested to evaluate the detectability of impact signals and assess the onset or threshold of impact damage. Testing was performed over a range of impact energy levels, where the sensors were adhered to the back of the specimens. The PVDF signal levels were analyzed and compared to assess damage, where digital microscopy, visual inspection, and white light interferometry were used for damage verification. Based on the impact test results, an assessment of the impact damage thresholds for each type of metallic TPS system was made.

Large-signal modeling of multi-finger InP DHBT devices at millimeter-wave frequencies

DEFF Research Database (Denmark)

Johansen, Tom Keinicke; Midili, Virginio; Squartecchia, Michele

2017-01-01

A large-signal modeling approach has been developed for multi-finger devices fabricated in an Indium Phosphide (InP) Double Heterojunction Bipolar Transistor (DHBT) process. The approach utilizes unit-finger device models embedded in a multi-port parasitic network. The unit-finger model is based...... on an improved UCSD HBT model formulation avoiding an erroneous RciCbci transit-time contribution from the intrinsic collector region as found in other III-V based HBT models. The mutual heating between fingers is modeled by a thermal coupling network with parameters extracted from electro-thermal simulations...

High thermal conductivity materials for thermal management applications

Science.gov (United States)

Broido, David A.; Reinecke, Thomas L.; Lindsay, Lucas R.

2018-05-29

High thermal conductivity materials and methods of their use for thermal management applications are provided. In some embodiments, a device comprises a heat generating unit (304) and a thermally conductive unit (306, 308, 310) in thermal communication with the heat generating unit (304) for conducting heat generated by the heat generating unit (304) away from the heat generating unit (304), the thermally conductive unit (306, 308, 310) comprising a thermally conductive compound, alloy or composite thereof. The thermally conductive compound may include Boron Arsenide, Boron Antimonide, Germanium Carbide and Beryllium Selenide.

Reliability evaluation of fiber optic sensors exposed to cyclic thermal load

Energy Technology Data Exchange (ETDEWEB)

Kim, Heon Young; Kim, Dong Hoon [Advanced Materials Research Team, Korea Railroad Research Institute, Uiwang (Korea, Republic of); Kim, Dae Hyun [Dept. of Mechanical and Automotive Engineering, Seoul National University of Science and Technology, Seoul (Korea, Republic of)

2016-06-15

Fiber Bragg grating (FBG) sensors are currently the most prevalent sensors because of their unique advantages such as ease of multiplexing and capability of performing absolute measurements. They are applied to various structures for structural health monitoring (SHM). The signal characteristics of FBG sensors under thermal loading should be investigated to enhance the reliability of these sensors, because they are exposed to certain cyclic thermal loads due to temperature changes resulting from change of seasons, when they are applied to structures for SHM. In this study, tests on specimens are conducted in a thermal chamber with temperature changes from - to for 300 cycles. For the specimens, two types of base materials and adhesives that are normally used in the manufacture of packaged FBG sensors are selected. From the test results, it is confirmed that the FBG sensors undergo some degree of compressive strain under cyclic thermal load; this can lead to measurement errors. Hence, a pre-calibration is necessary before applying these sensors to structures for long-term SHM.

Thermal Properties and Thermal Analysis:

Science.gov (United States)

Kasap, Safa; Tonchev, Dan

The chapter provides a summary of the fundamental concepts that are needed to understand the heat capacity C P, thermal conductivity κ, and thermal expansion coefficient α L of materials. The C P, κ, and α of various classes of materials, namely, semiconductors, polymers, and glasses, are reviewed, and various typical characteristics are summarized. A key concept in crystalline solids is the Debye theory of the heat capacity, which has been widely used for many decades for calculating the C P of crystals. The thermal properties are interrelated through Grüneisen's theorem. Various useful empirical rules for calculating C P and κ have been used, some of which are summarized. Conventional differential scanning calorimetry (DSC) is a powerful and convenient thermal analysis technique that allows various important physical and chemical transformations, such as the glass transition, crystallization, oxidation, melting etc. to be studied. DSC can also be used to obtain information on the kinetics of the transformations, and some of these thermal analysis techniques are summarized. Temperature-modulated DSC, TMDSC, is a relatively recent innovation in which the sample temperature is ramped slowly and, at the same time, sinusoidally modulated. TMDSC has a number of distinct advantages compared with the conventional DSC since it measures the complex heat capacity. For example, the glass-transition temperature T g measured by TMDSC has almost no dependence on the thermal history, and corresponds to an almost step life change in C P. The new Tzero DSC has an additional thermocouple to calibrate better for thermal lags inherent in the DSC measurement, and allows more accurate thermal analysis.

Properties of the lithium carbonate for to be used as thermal neutrons detector

International Nuclear Information System (INIS)

Herrera A, E.; Urena N, F.

2003-01-01

In this work the dosimetric properties of the lithium carbonate used as detecting of thermal neutrons and by means of free radicals is evaluated and presented. The studied parameters that were carried out for this detector were: intensity of the Electron paramagnetic resonance signal (EPR); reproducibility, fading of the signal to ambient temperature, stability of the signal to low temperature (0 degrees); answer of zero dose and homogeneity or reliability of the data of the detector, humidity, solar light, temperature and radio sensitivity. These parameters indicate the utility that have the detectors for the estimation of fields of neutron fluences that are applicable to capture therapies by neutron-boron and, nuclear reactors. (Author)

Sunyaev–Zel’Dovich Signal from Quasar Hosts: Implications for Detection of Quasar Feedback

Energy Technology Data Exchange (ETDEWEB)

Chowdhury, Dhruba Dutta; Chatterjee, Suchetana, E-mail: dhruba.duttachowdhury@yale.edu [Department of Physics, Presidency University, Kolkata, 700073 (India)

2017-04-10

Several analytic and numerical studies have indicated that the interstellar medium of a quasar host galaxy heated by feedback can contribute to a substantial secondary signal in the cosmic microwave background (CMB) through the thermal Sunyaev–Zel’dovich (SZ) effect. Recently, many groups have tried to detect this signal by cross-correlating CMB maps with quasar catalogs. Using a self-similar model for the gas in the intra-cluster medium and a realistic halo occupation distribution (HOD) prescription for quasars, we estimate the level of SZ signal from gravitational heating of quasar hosts. The bias in the host halo signal estimation due to an unconstrained high mass HOD tail and yet unknown redshift dependence of the quasar HOD restricts us from drawing any robust conclusions at low redshift ( z < 1.5) from our analysis. However, at higher redshifts ( z > 2.5), we find an excess signal in recent observations than what is predicted from our model. The excess signal could be potentially generated from additional heating due to quasar feedback.

Sunyaev–Zel’Dovich Signal from Quasar Hosts: Implications for Detection of Quasar Feedback

International Nuclear Information System (INIS)

Chowdhury, Dhruba Dutta; Chatterjee, Suchetana

2017-01-01

Several analytic and numerical studies have indicated that the interstellar medium of a quasar host galaxy heated by feedback can contribute to a substantial secondary signal in the cosmic microwave background (CMB) through the thermal Sunyaev–Zel’dovich (SZ) effect. Recently, many groups have tried to detect this signal by cross-correlating CMB maps with quasar catalogs. Using a self-similar model for the gas in the intra-cluster medium and a realistic halo occupation distribution (HOD) prescription for quasars, we estimate the level of SZ signal from gravitational heating of quasar hosts. The bias in the host halo signal estimation due to an unconstrained high mass HOD tail and yet unknown redshift dependence of the quasar HOD restricts us from drawing any robust conclusions at low redshift ( z < 1.5) from our analysis. However, at higher redshifts ( z > 2.5), we find an excess signal in recent observations than what is predicted from our model. The excess signal could be potentially generated from additional heating due to quasar feedback.

Semiconductor Thermal Neutron Detector

Directory of Open Access Journals (Sweden)

Toru Aoki

2014-02-01

Full Text Available The  CdTe  and  GaN  detector  with  a  Gd  converter  have  been developed  and  investigated  as  a  neutron  detector  for neutron  imaging.  The  fabricated  Gd/CdTe  detector  with  the  25  mm  thick  Gd  was  designed  on  the  basis  of  simulation results  of  thermal  neutron  detection  efficiency  and  spatial  resolution.  The  Gd/CdTe  detector  shows  the  detection  of neutron  capture  gamma  ray  emission  in  the  155Gd(n,  g156Gd,  157Gd(n,  g158Gd  and  113Cd(n,  g114Cd  reactions  and characteristic X-ray emissions due to conversion-electrons generated inside the Gd film. The observed efficient thermal neutron detection with the Gd/CdTe detector shows its promise in neutron radiography application. Moreover, a BGaN detector has also investigated to separate neutron signal from gamma-ray clearly. 

Earthquake prediction using extinct monogenetic volcanoes: A possible new research strategy

Science.gov (United States)

Szakács, Alexandru

2011-04-01

using an assemblage of physical, chemical and biological sensors devised to detect precursory signals. Earthquake prediction systems can be built up based on the concept of a signal emission-transmission-reception system, in which volcanic conduits and/or deep fractures play the role of the most effective signal transmission paths through the lithosphere. Unique "precursory fingerprints" of individual seismic structures are expected to be pointed out as an outcome of target-oriented strategic prediction research. Intelligent pattern-recognition systems are to be included for evaluation of the signal assemblages recorded by complex sensor arrays. Such strategies are expected however to be limited to intermediate-depth and deep seismic structures. Due to its particular features and geotectonic setting, the Vrancea seismic structure in Romania appears to be an excellent experimental target for prediction research.

Influence of the Mg-content on ESR-signals in synthetic calcium carbonate

International Nuclear Information System (INIS)

Barabas, M.; Bach, A.; Mudelsee, M.; Mangini, A.

1989-01-01

Carbonate crystals doped with various concentrations of Mg 2+ -ions have been grown by a gel-diffusion method. An increase of the Mg/Ca-ratio to more than about 1 caused a phase change in the crystal lattice from calcite to aragonite. The properties of the ESR-signals of the synthetic carbonates were studied and compared with natural marine carbonates. The following results were derived: (a) In the presence of Mg 2+ -ions the synthetic carbonates display the same ESR-signals as natural calcites of marine origin with similar properties (thermal stability, radiation sensitivity). (b) The saturation value of the signal at g=2.0006 in synthetic calcites was found to be strongly related with the Mg-content in the crystals. (c) The signal at g=2.0036 (axial symmetry) which is present in calcite was not influenced by the Mg-concentration. Its saturation value decreases when the crystal phase changed from calcite to aragonite and in complement the signal at g=2.0031 appeared. (d) The signals at g=2.0057 and g=2.0031 are most probably not of organic origin. (author)

Analysis of thermally induced magnetization dynamics in spin-transfer nano-oscillators

Energy Technology Data Exchange (ETDEWEB)

D' Aquino, M., E-mail: daquino@uniparthenope.it [Department of Technology, University of Naples ' Parthenope' , 80143 Naples (Italy); Serpico, C. [Department of Engineering, University of Naples Federico II, 80125 Naples (Italy); Bertotti, G. [Istituto Nazionale di Ricerca Metrologica 10135 Torino (Italy); Bonin, R. [Politecnico di Torino - Sede di Verres, 11029 Verres (Aosta) (Italy); Mayergoyz, I.D. [ECE Department and UMIACS, University of Maryland, College Park, MD 20742 (United States)

2012-05-01

The thermally induced magnetization dynamics in the presence of spin-polarized currents injected into a spin-valve-like structure used as microwave spin-transfer nano-oscillator (STNO) is considered. Magnetization dynamics is described by the stochastic Landau-Lifshitz-Slonczewski (LLS) equation. First, it is shown that, in the presence of thermal fluctuations, the spectrum of the output signal of the STNO exhibits multiple peaks at low and high frequencies. This circumstance is associated with the occurrence of thermally induced transitions between stationary states and magnetization self-oscillations. Then, a theoretical approach based on the separation of time-scales is developed to obtain a stochastic dynamics only in the slow state variable, namely the energy. The stationary distribution of the energy and the aforementioned transition rates are analytically computed and compared with the results of direct integration of the LLS dynamics, showing very good agreement.

Bis(pinacolato)diboron as an additive for the detection of thermal neutrons in plastic scintillators

Energy Technology Data Exchange (ETDEWEB)

Mahl, Adam [Department of Physics and the Nuclear Science and Engineering Center (NuSEC), Colorado School of Mines, Golden, CO 80401 (United States); Yemam, Henok A.; Stuntz, John [Department of Chemistry and Geochemistry and the Materials Science Program Colorado School of Mines, Golden, CO 80401 (United States); Remedes, Tyler [Department of Physics and the Nuclear Science and Engineering Center (NuSEC), Colorado School of Mines, Golden, CO 80401 (United States); Sellinger, Alan [Department of Chemistry and Geochemistry and the Materials Science Program Colorado School of Mines, Golden, CO 80401 (United States); Greife, Uwe, E-mail: ugreife@mines.edu [Department of Physics and the Nuclear Science and Engineering Center (NuSEC), Colorado School of Mines, Golden, CO 80401 (United States)

2016-04-21

A readily available and inexpensive boron compound was tested as an additive for the detection of thermal neutrons in plastic scintillators. Bis(pinacolato)diboron (B{sub 2}Pin{sub 2}) was determined to be a compatible boron source (8.51 wt% boron, 1.70 wt% {sup 10}B) in poly(vinyltoluene) based matrices. Plastic scintillator blends of 1–20 wt% 2,5-diphenyloxazole (PPO), 0.1 wt% 1,4-bis(5-phenyloxazol-2-yl) benzene (POPOP) and 1–15 wt% B{sub 2}Pin{sub 2} were prepared that provided optical clarity, good mechanical properties, and the capability of thermal neutron detection. Independent of B{sub 2}Pin{sub 2} concentration, strong {sup 10}B neutron capture signals around 90 keV{sub ee} were observed at essentially constant light output. Increasing PPO concentration allowed for the use of pulse shape discrimination (PSD) in both fast and thermal neutron detection. High PPO concentrations appear to cause additional alpha quenching that affected the {sup 10}B neutron capture signal. Aging effects after storage in air for several months were observed, which led to degradation of performance and in some samples of mechanical stability.

Bis(pinacolato)diboron as an additive for the detection of thermal neutrons in plastic scintillators

International Nuclear Information System (INIS)

Mahl, Adam; Yemam, Henok A.; Stuntz, John; Remedes, Tyler; Sellinger, Alan; Greife, Uwe

2016-01-01

A readily available and inexpensive boron compound was tested as an additive for the detection of thermal neutrons in plastic scintillators. Bis(pinacolato)diboron (B_2Pin_2) was determined to be a compatible boron source (8.51 wt% boron, 1.70 wt% "1"0B) in poly(vinyltoluene) based matrices. Plastic scintillator blends of 1–20 wt% 2,5-diphenyloxazole (PPO), 0.1 wt% 1,4-bis(5-phenyloxazol-2-yl) benzene (POPOP) and 1–15 wt% B_2Pin_2 were prepared that provided optical clarity, good mechanical properties, and the capability of thermal neutron detection. Independent of B_2Pin_2 concentration, strong "1"0B neutron capture signals around 90 keV_e_e were observed at essentially constant light output. Increasing PPO concentration allowed for the use of pulse shape discrimination (PSD) in both fast and thermal neutron detection. High PPO concentrations appear to cause additional alpha quenching that affected the "1"0B neutron capture signal. Aging effects after storage in air for several months were observed, which led to degradation of performance and in some samples of mechanical stability.

Submicron InP DHBT technology for high-speed high-swing mixed-signal ICs

DEFF Research Database (Denmark)

Godin, Jean; Nodjiadjim, V.; Riet, Muriel

2008-01-01

We report on the development of a submicron InP DHBT technology, optimized for the fabrication of 50-GHz-clock mixed signal ICs. In-depth study of device geometry and structure has allowed to get the needed performances and yield. Special attention has been paid to critical thermal behavior. Vari...... applications of interest....

Spectral and Thermal Degradation of Melamine Cyanurate

Directory of Open Access Journals (Sweden)

V. Sangeetha

2013-01-01

Full Text Available Melamine cyanurate, an organic crystalline complex was, synthesized by evaporation of an aqueous solution containing equimolar quantities of melamine and cyanuric acid. The synthesized compound has been subjected to various characterizations like Powder XRD, FT-IR, TG-DTG, SEM, and SHG. The presence of sharp diffraction peaks in the XRD confirms that the products are highly crystalline. The average particle size was calculated using the Debye-Scherrer formula, and it was found to be 3.067 μm. Thermal behavior of the grown crystal has been studied by TG-DTG analysis. From TG-DTG, it is found that the title crystal possesses good thermal stability. The activation energy was calculated using the Broido, Coats-Redfern, and Horowitz-Metzger methods. A sharp peak exothermic peak at 405.40°C was assigned as the melting point of the title material. SEM reveals the morphology of the synthesized salt. No detectable signal was observed during the Kurtz-Perry technique.

Thoughts on non-perturbative thermalization and jet quenching in heavy ion collisions

International Nuclear Information System (INIS)

Kovchegov, Yuri V.

2006-01-01

We start by presenting physical arguments for the impossibility of perturbative thermalization leading to (non-viscous) Bjorken hydrodynamic description of heavy ion collisions. These arguments are complimentary to our more formal argument presented in [Yu.V. Kovchegov, hep-ph/0503038]. We argue that the success of hydrodynamic models in describing the quark-gluon system produced in heavy ion collisions could only be due to non-perturbative strong coupling effects. We continue by studying non-perturbative effects in heavy ion collisions at high energies. We model non-perturbative phenomena by an instanton ensemble. We show that non-perturbative instanton vacuum fields may significantly contribute to jet quenching in nuclear collisions. At the same time, the instanton ensemble contribution to thermalization is likely to be rather weak, leading to non-perturbative thermalization time comparable to the time of hadronization. This example illustrates that jet quenching is not necessarily a signal of a thermalized medium. Indeed, since the instanton models do not capture all the effects of QCD vacuum (e.g., they do not account for confinement), there may be other non-perturbative effects facilitating thermalization of the system

Comparative expression profile of NOD1/2 and certain acute inflammatory cytokines in thermal-stressed cell culture model of native and crossbred cattle

Science.gov (United States)

Bhanuprakash, V.; Singh, Umesh; Sengar, Gyanendra Singh; Raja, T. V.; Sajjanar, Basavraj; Alex, Rani; Kumar, Sushil; Alyethodi, R. R.; Kumar, Ashish; Sharma, Ankur; Kumar, Suresh; Bhusan, Bharat; Deb, Rajib

2017-05-01

Thermotolerance depends mainly on the health and immune status of the animals. The variation in the immune status of the animals may alter the level of tolerance of animals exposed to heat or cold stress. The present study was conducted to investigate the expression profile of two important nucleotide binding and oligomerization domain receptors (NLRs) (NOD1 and NOD2) and their central signalling molecule RIP2 gene during in vitro thermal-stressed bovine peripheral blood mononuclear cells (PBMCs) of native (Sahiwal) and crossbred (Sahiwal X HF) cattle. We also examined the differential expression profile of certain acute inflammatory cytokines in in vitro thermal-stressed PBMC culture among native and its crossbred counterparts. Results revealed that the expression profile of NOD1/2 positively correlates with the thermal stress, signalling molecule and cytokines. Present findings also highlighted that the expression patterns during thermal stress were comparatively superior among indigenous compared to crossbred cattle which may add references regarding the better immune adaptability of Zebu cattle.

A candidate multimodal functional genetic network for thermal adaptation

Directory of Open Access Journals (Sweden)

Katharina C. Wollenberg Valero

2014-09-01

Full Text Available Vertebrate ectotherms such as reptiles provide ideal organisms for the study of adaptation to environmental thermal change. Comparative genomic and exomic studies can recover markers that diverge between warm and cold adapted lineages, but the genes that are functionally related to thermal adaptation may be difficult to identify. We here used a bioinformatics genome-mining approach to predict and identify functions for suitable candidate markers for thermal adaptation in the chicken. We first established a framework of candidate functions for such markers, and then compiled the literature on genes known to adapt to the thermal environment in different lineages of vertebrates. We then identified them in the genomes of human, chicken, and the lizard Anolis carolinensis, and established a functional genetic interaction network in the chicken. Surprisingly, markers initially identified from diverse lineages of vertebrates such as human and fish were all in close functional relationship with each other and more associated than expected by chance. This indicates that the general genetic functional network for thermoregulation and/or thermal adaptation to the environment might be regulated via similar evolutionarily conserved pathways in different vertebrate lineages. We were able to identify seven functions that were statistically overrepresented in this network, corresponding to four of our originally predicted functions plus three unpredicted functions. We describe this network as multimodal: central regulator genes with the function of relaying thermal signal (1, affect genes with different cellular functions, namely (2 lipoprotein metabolism, (3 membrane channels, (4 stress response, (5 response to oxidative stress, (6 muscle contraction and relaxation, and (7 vasodilation, vasoconstriction and regulation of blood pressure. This network constitutes a novel resource for the study of thermal adaptation in the closely related nonavian reptiles and

Evaluation of Ultrasonic and Thermal Nondestructive Evaluation for the Characterization of Aging Degradation in Braided Composite Materials

Science.gov (United States)

Martin, Richard E.

2010-01-01

This paper examines the ability of traditional nondestructive evaluation (NDE) techniques to measure the degradation of braided polymer composite materials subjected to thermal-humidity cycling to simulate aging. A series of braided composite coupons were examined using immersion ultrasonic and pulsed thermography techniques in the as received condition. These same specimens were then examined following extended thermal-humidity cycling. Results of this examination did not show a significant change in the resulting (NDE) signals.

Results of subionospheric radio LF monitoring prior to the Tokachi (M=8, Hokkaido, 25 September 2003 earthquake

Directory of Open Access Journals (Sweden)

A. V. Shvets

2004-01-01

Full Text Available Results of simultaneous LF subionospheric monitoring over two different propagation paths prior to the very strong Tokachi earthquake (near the east coast of Hokkaido Island, 25 September 2003 of magnitude 8.3 are presented firstly. Nighttime amplitude fluctuations of the Japanese Time Standard Transmitter (JG2AS, 40kHz signal received at Moshiri (Japan, 142°E, 44°N and at Petropavlovsk-Kamchatski (Russia, 158°E, 53°N were analyzed. As a possible precursory signature we observed synchronous intensification of quasi periodical 16-day variations of the dispersion in the signals received at both observation stations before the earthquake. The strongest deviations observed as a rule were depletions of signal amplitude probably connected with increase of loss in the ionosphere by the enhancement of turbulence. This is due to dissipation of internal gravity waves (IGW at the lower ionosphere heights. A scheme for seismo-IGW-planetary waves (PW interconnection has been justified to explain the observed connection with strong earthquakes. It considers the seasonal variability in the signal.

Validation of Atmosphere/Ionosphere Signals Associated with Major Earthquakes by Multi-Instrument Space-Borne and Ground Observations

Science.gov (United States)

Ouzounov, Dimitar; Pulinets, Sergey; Hattori, Katsumi; Parrot, Michel; Liu, J. Y.; Yang, T. F.; Arellano-Baeza, Alonso; Kafatos, M.; Taylor, Patrick

2012-01-01

The latest catastrophic earthquake in Japan (March 2011) has renewed interest in the important question of the existence of pre-earthquake anomalous signals related to strong earthquakes. Recent studies have shown that there were precursory atmospheric/ionospheric signals observed in space associated with major earthquakes. The critical question, still widely debated in the scientific community, is whether such ionospheric/atmospheric signals systematically precede large earthquakes. To address this problem we have started to investigate anomalous ionospheric / atmospheric signals occurring prior to large earthquakes. We are studying the Earth's atmospheric electromagnetic environment by developing a multisensor model for monitoring the signals related to active tectonic faulting and earthquake processes. The integrated satellite and terrestrial framework (ISTF) is our method for validation and is based on a joint analysis of several physical and environmental parameters (thermal infrared radiation, electron concentration in the ionosphere, lineament analysis, radon/ion activities, air temperature and seismicity) that were found to be associated with earthquakes. A physical link between these parameters and earthquake processes has been provided by the recent version of Lithosphere-Atmosphere-Ionosphere Coupling (LAIC) model. Our experimental measurements have supported the new theoretical estimates of LAIC hypothesis for an increase in the surface latent heat flux, integrated variability of outgoing long wave radiation (OLR) and anomalous variations of the total electron content (TEC) registered over the epicenters. Some of the major earthquakes are accompanied by an intensification of gas migration to the surface, thermodynamic and hydrodynamic processes of transformation of latent heat into thermal energy and with vertical transport of charged aerosols in the lower atmosphere. These processes lead to the generation of external electric currents in specific

Video and thermal imaging system for monitoring interiors of high temperature reaction vessels

Science.gov (United States)

Saveliev, Alexei V [Chicago, IL; Zelepouga, Serguei A [Hoffman Estates, IL; Rue, David M [Chicago, IL

2012-01-10

A system and method for real-time monitoring of the interior of a combustor or gasifier wherein light emitted by the interior surface of a refractory wall of the combustor or gasifier is collected using an imaging fiber optic bundle having a light receiving end and a light output end. Color information in the light is captured with primary color (RGB) filters or complimentary color (GMCY) filters placed over individual pixels of color sensors disposed within a digital color camera in a BAYER mosaic layout, producing RGB signal outputs or GMCY signal outputs. The signal outputs are processed using intensity ratios of the primary color filters or the complimentary color filters, producing video images and/or thermal images of the interior of the combustor or gasifier.

Testing and linearity calibration of films of phenol compounds exposed to thermal neutron field for EPR dosimetry.

Science.gov (United States)

Gallo, S; Panzeca, S; Longo, A; Altieri, S; Bentivoglio, A; Dondi, D; Marconi, R P; Protti, N; Zeffiro, A; Marrale, M

2015-12-01

This paper reports the preliminary results obtained by Electron Paramagnetic Resonance (EPR) measurements on films of IRGANOX® 1076 phenols with and without low content (5% by weight) of gadolinium oxide (Gd2O3) exposed in the thermal column of the Triga Mark II reactor of LENA (Laboratorio Energia Nucleare Applicata) of Pavia (Italy). Thanks to their size, the phenolic films here presented are good devices for the dosimetry of beams with high dose gradient and which require accurate knowledge of the precise dose delivered. The dependence of EPR signal as function of neutron dose was investigated in the fluence range between 10(11) cm(-2) and 10(14) cm(-2). Linearity of EPR response was found and the signal was compared with that of commercial alanine films. Our analysis showed that gadolinium oxide (5% by weight) can enhance the thermal neutron sensitivity more than 18 times. Irradiated dosimetric films of phenolic compound exhibited EPR signal fading of about 4% after 10 days from irradiation. Copyright © 2015 Elsevier Ltd. All rights reserved.

High-sensitivity broadband infrared monitor of spatial structure of relativistic bunches and thermal fields

International Nuclear Information System (INIS)

Mal'tsev, A.A.; Mal'tsev, M.A.; Maslova, M.V.

2004-01-01

The monitor is intended for registration of spatial distribution of density of energy of pulsing radiation of thermal fields and bunches of relativistic electrons and protons in a wide spectral range 0,4 - 4 μm. In a measuring system of a monitor effective means of active and passive increase of the relation of a useful signal to noise, in view of particular conditions and requirements are used. The measuring channel can confidently allocate a useful signal on a background of handicaps, the size of which can make about 20 kE in a pulse [1]. The accuracy of measurement of amplitude of a signal of radiation makes 0,2% of maximum significances of a registrar scale. (author)

A Preliminary Assessment of Soviet Development of Optimum Signal Discrimination Techniques: Optimum Space-Time Processing

Science.gov (United States)

1982-10-01

thermal noise and radioastronomy is probably the application Shirman had in mind for that work. Kuriksha considers a wide class of two-dimensional...this point has been discussed In terms of EM wave propagation, signal detection, and parameter estimation in such fields as radar and radioastronomy

Response of turkey muscle satellite cells to thermal challenge. I. transcriptome effects in proliferating cells.

Science.gov (United States)

Reed, Kent M; Mendoza, Kristelle M; Abrahante, Juan E; Barnes, Natalie E; Velleman, Sandra G; Strasburg, Gale M

2017-05-06

Climate change poses a multi-dimensional threat to food and agricultural systems as a result of increased risk to animal growth, development, health, and food product quality. This study was designed to characterize transcriptional changes induced in turkey muscle satellite cells cultured under cold or hot thermal challenge to better define molecular mechanisms by which thermal stress alters breast muscle ultrastructure. Satellite cells isolated from the pectoralis major muscle of 7-weeks-old male turkeys from two breeding lines (16 weeks body weight-selected and it's randombred control) were proliferated in culture at 33 °C, 38 °C or 43 °C for 72 h. Total RNA was isolated and 12 libraries subjected to RNAseq analysis. Statistically significant differences in gene expression were observed among treatments and between turkey lines with a greater number of genes altered by cold treatment than by hot and fewer differences observed between lines than between temperatures. Pathway analysis found that cold treatment resulted in an overrepresentation of genes involved in cell signaling/signal transduction and cell communication/cell signaling as compared to control (38 °C). Heat-treated muscle satellite cells showed greater tendency towards expression of genes related to muscle system development and differentiation. This study demonstrates significant transcriptome effects on turkey skeletal muscle satellite cells exposed to thermal challenge. Additional effects on gene expression could be attributed to genetic selection for 16 weeks body weight (muscle mass). New targets are identified for further research on the differential control of satellite cell proliferation in poultry.

Local Thermal Insulating Materials For Thermal Energy Storage ...

African Journals Online (AJOL)

Thermal insulation is one of the most important components of a thermal energy storage system. In this paper the thermal properties of selected potential local materials which can be used for high temperature insulation are presented. Thermal properties of seven different samples were measured. Samples consisted of: ...

Thermal resistance matrix representation of thermal effects and thermal design in multi-finger power heterojunction bipolar transistors

Institute of Scientific and Technical Information of China (English)

Jin Dong-Yue; Zhang Wan-Rong; Chen Liang; Fu Qiang; Xiao Ying; Wang Ren-Qing; Zhao Xin

2011-01-01

The thermal resistance matrix including self-heating thermal resistance and thermal coupling resistance is presented to describe the thermal effects of multi-finger power heterojunction bipolar transistors. The dependence of thermal resistance matrix on finger spacing is also investigated. It is shown that both self-heating thermal resistance and thermal coupling resistance are lowered by increasing the finger spacing, in which the downward dissipated heat path is widened and the heat flow from adjacent fingers is effectively suppressed. The decrease of self-heating thermal resistance and thermal coupling resistance is helpful for improving the thermal stability of power devices. Furthermore, with the aid of the thermal resistance matrix, a 10-finger power heterojunction bipolar transistor (HBT) with non-uniform finger spacing is designed for high thermal stability. The optimized structure can effectively lower the peak temperature while maintaining a uniformity of the temperature profile at various biases and thus the device effectively may operate at a higher power level.

Thermal Effects Induced by Laser Irradiation of Solids

International Nuclear Information System (INIS)

Galovic, S.

2004-01-01

A part of incident energy is absorbed within the irradiated sample when a solid is exposed to the influence of laser radiation, to more general electromagnetic radiation within the wide range of wavelengths (from microwaves, to infrared radiation to X-rays), or to the energy of particle beams (electronic, protonic, or ionic). The absorption process signifies a highly selective excitation of the electronic state of atoms or molecules, followed by thermal and non-thermal de-excitation processes. Non-radiation de-excitation-relaxation processes induce direct sample heating. In addition, a great number of non-thermal processes (e.g., photoluminescence, photochemistry, photovoltage) may also induce heat generation as a secondary process. This method of producing heat is called the photothermal effect.The photothermal effect and subsequent propagation of thermal waves on the surface and in the volume of the solid absorbing the exciting beam may produce the following: variations in the temperature on the surfaces of the sample; deformation and displacement of surfaces; secondary infrared radiation (photothermal radiation); the formation of the gradient of the refractivity index; changes in coefficients of reflection and absorbtion; the generation of sound (photoacoustic generation), etc. These phenomena may be used in the investigation and measurement of various material properties since the profile and magnitude of the generated signal depend upon the nature of material absorbing radiation. A series of non-destructive spectroscopic, microscopic and defectoscopic detecting techniques, called photothermal methods, is developed on the basis of the above-mentioned phenomena.This paper outlines the interaction between the intensity modulated laser beam and solids, and presents a mathematical model of generated thermal sources. Generalized models for a photothermal response of optically excited materials have been obtained, including thermal memory influence on the propagation

Thermal pressure and isochoric thermal conductivity of solid CO2

International Nuclear Information System (INIS)

Purs'kij, O.Yi.

2005-01-01

The analysis of the correlation between the thermal pressure and the isochoric thermal conductivity of solid CO 2 has been carried out. The temperature dependences of the thermal pressure and isochoric thermal conductivity for samples with various molar volumes have been obtained. The isothermal pressure dependences of the thermal conductivity of solid CO 2 have been calculated. The form of the temperature dependence of the isochoric thermal conductivity taking the thermal pressure into account has been revealed. Behaviour of the isochoric thermal conductivity is explained by phonon-phonon interaction and additional influence of the thermal pressure

Thermal stress mitigation by Active Thermal Control

DEFF Research Database (Denmark)

Soldati, Alessandro; Dossena, Fabrizio; Pietrini, Giorgio

2017-01-01

This work proposes an Active Thermal Control (ATC) of power switches. Leveraging on the fact that thermal stress has wide impact on the system reliability, controlling thermal transients is supposed to lengthen the lifetime of electronic conversion systems. Indeed in some environments...... results of control schemes are presented, together with evaluation of the proposed loss models. Experimental proof of the ability of the proposed control to reduce thermal swing and related stress on the device is presented, too....

Anisotropic Thermal Diffusivities of Plasma-Sprayed Thermal Barrier Coatings

Science.gov (United States)

Akoshima, Megumi; Takahashi, Satoru

2017-09-01

Thermal barrier coatings (TBCs) are used to shield the blades of gas turbines from heat and wear. There is a pressing need to evaluate the thermal conductivity of TBCs in the thermal design of advanced gas turbines with high energy efficiency. These TBCs consist of a ceramic-based top coat and a bond coat on a superalloy substrate. Usually, the focus is on the thermal conductivity in the thickness direction of the TBC because heat tends to diffuse from the surface of the top coat to the substrate. However, the in-plane thermal conductivity is also important in the thermal design of gas turbines because the temperature distribution within the turbine cannot be ignored. Accordingly, a method is developed in this study for measuring the in-plane thermal diffusivity of the top coat. Yttria-stabilized zirconia top coats are prepared by thermal spraying under different conditions. The in-plane and cross-plane thermal diffusivities of the top coats are measured by the flash method to investigate the anisotropy of thermal conduction in a TBC. It is found that the in-plane thermal diffusivity is higher than the cross-plane one for each top coat and that the top coats have significantly anisotropic thermal diffusivity. The cross-sectional and in-plane microstructures of the top coats are observed, from which their porosities are evaluated. The thermal diffusivity and its anisotropy are discussed in detail in relation to microstructure and porosity.

Apollo telescope mount thermal systems unit thermal vacuum test

Science.gov (United States)

Trucks, H. F.; Hueter, U.; Wise, J. H.; Bachtel, F. D.

1971-01-01

The Apollo Telescope Mount's thermal systems unit was utilized to conduct a full-scale thermal vacuum test to verify the thermal design and the analytical techniques used to develop the thermal mathematical models. Thermal vacuum test philosophy, test objectives configuration, test monitoring, environment simulation, vehicle test performance, and data correlation are discussed. Emphasis is placed on planning and execution of the thermal vacuum test with particular attention on problems encountered in conducting a test of this maguitude.

Mechanical Behaviour of Stainless Steels under Dynamic Loading: An Investigation with Thermal Methods

Directory of Open Access Journals (Sweden)

Rosa De Finis

2016-11-01

Full Text Available Stainless steels are the most exploited materials due to their high mechanical strength and versatility in producing different alloys. Although there is great interest in these materials, mechanical characterisation, in particular fatigue characterisation, requires the application of several standardised procedures involving expensive and time-consuming experimental campaigns. As a matter of fact, the use of Standard Test Methods does not rely on a physical approach, since they are based on a statistical evaluation of the fatigue limit with a fixed probabilistic confidence. In this regard, Infra-Red thermography, the well-known, non-destructive technique, allows for the development of an approach based on evaluation of dissipative sources. In this work, an approach based on a simple analysis of a single thermographic sequence has been presented, which is capable of providing two indices of the damage processes occurring in material: the phase shift of thermoelastic signal φ and the amplitude of thermal signal at twice the loading frequency, S2. These thermal indices can provide synergetic information about the mechanical (fatigue and fracture behaviour of austenitic AISI 316L and martensitic X4 Cr Ni Mo 16-5-1; since they are related to different thermal effects that produce damage phenomena. In particular, the use of φ and S2 allows for estimation of the fatigue limit of stainless steels at loading ratio R = 0.5 in agreement with the applied Standard methods. Within Fracture Mechanics tests, both indices demonstrate the capacity to localize the plastic zone and determine the position of the crack tip. Finally, it will be shown that the value of the thermoelastic phase signal can be correlated with the mechanical behaviour of the specific material (austenitic or martensitic.

Thermally induced structural modifications and O2 trapping in highly porous silica nanoparticles

International Nuclear Information System (INIS)

Alessi, A.; Agnello, S.; Iovino, G.; Buscarino, G.; Melodia, E.G.; Cannas, M.; Gelardi, F.M.

2014-01-01

In this work we investigate by Raman spectroscopy the effect of isochronal (2 h) thermal treatments in air in the temperature range 200–1000 °C of amorphous silicon dioxide porous nanoparticles with diameters ranging from 5 up to 15 nm and specific surface 590–690 m 2 /g. Our results indicate that the amorphous structure changes similarly to other porous systems previously investigated, in fact superficial SiOH groups are removed, Si–O–Si linkages are created and the ring statistic is modified, furthermore these data evidence that the three membered rings do not contribute significantly to the Raman signal detected at about 495 cm −1 . In addition, after annealing at 900 and 1000 °C we noted the appearance of the O 2 emission at 1272 nm, absent in the not treated samples. The measure of the O 2 emission has been combined with electron paramagnetic resonance measurements of the γ irradiation induced HO · 2 radicals to investigate the O 2 content per mass unit of thin layers of silica. Our data reveal that the porous nanoparticles have a much lower ability to trap O 2 molecules per mass units than nonporous silica supporting a model by which O 2 trapping inside a surface layer of about 1 nm of silica is always limited. - Highlights: • O 2 emission and HO · 2 electron paramagnetic resonance signals are investigated. • Silica surface ability to trap O 2 molecules is explored by thermal treatments. • Raman study of thermally induced structural changes in porous silica nanoparticles. • Raman signal attributable to the three membered rings in silica

Thermal Management and Thermal Protection Systems

Science.gov (United States)

Hasnain, Aqib

2016-01-01

During my internship in the Thermal Design Branch (ES3), I contributed to two main projects: i) novel passive thermal management system for future human exploration, ii) AVCOAT undercut thermal analysis. i) As NASA prepares to further expand human and robotic presence in space, it is well known that spacecraft architectures will be challenged with unprecedented thermal environments. Future exploration activities will have the need of thermal management systems that can provide higher reliability, mass and power reduction and increased performance. In an effort to start addressing the current technical gaps the NASA Johnson Space Center Passive Thermal Discipline has engaged in technology development activities. One of these activities was done through an in-house Passive Thermal Management System (PTMS) design for a lunar lander. The proposed PTMS, functional in both microgravity and gravity environments, consists of three main components: a heat spreader, a novel hybrid wick Variable Conductance Heat Pipe (VCHP), and a radiator. The aim of this PTMS is to keep electronics on a vehicle within their temperature limits (0 and 50 C for the current design) during all mission phases including multiple lunar day/night cycles. The VCHP was tested to verify its thermal performance. I created a thermal math model using Thermal Desktop (TD) and analyzed it to predict the PTMS performance. After testing, the test data provided a means to correlate the thermal math model. This correlation took into account conduction and convection heat transfer, representing the actual benchtop test. Since this PTMS is proposed for space missions, a vacuum test will be taking place to provide confidence that the system is functional in space environments. Therefore, the model was modified to include a vacuum chamber with a liquid nitrogen shroud while taking into account conduction and radiation heat transfer. Infrared Lamps were modelled and introduced into the model to simulate the sun

Theory and practice of near-field thermal probes for microscopy and thermal analysis

International Nuclear Information System (INIS)

Hodges, C.S.

1999-03-01

Bacterial mats called biofilms that form on the surfaces of industrial steel pipes can cause corrosion of the pipe. Examining the steel surface of the corroded pipe usually involves removal of the biofilm using acid. This acid can also cause corrosion of the pipe so that the observed corrosion cracks and pits are the result of both the acid and the biofilm. It was thought that non-invasive examination of the corrosion caused by the biofilm may be obtained by using a thin wire bent into a loop that acts as both a heat source a nd a detector of heat, measuring the changes in heat flow out of the wire as the wire passes over the steel with the biofilm still present. This technique of using a heated probe to scan samples on a microscopic scale is called Scanning Thermal Microscopy (SThM) and uses an alternating current to produce a.c. thermal waves that emanate from the probe tip into the sample. The alternating current allows better signal-to-noise ratios and also selective depth imaging of the sample since the thermal wave penetrates into the sample a distance inversely proportional to the applied current frequency. Reversal in the contrast of SThM images on biofilms and subsequently all samples was observed as either the frequency or the amplitude of the temperature waves was altered. Whilst changing the time constant of the feedback circuit attached to the SThM probe did go some way to explain this effect, a full explanation is still wanting. Despite many efforts to image the biofilm/steel interface with the biofilm still present, often the biofilm was either too thick or too complicated to do this. A simpler thermal test sample is required to calibrate the thermal probe. In addition to SThM, one may select a point on a sample surface and ramp the temperature of the probe to obtain a Localised Thermal Analysis (LTA) temperature scan looking for melts, recrystallisations, glass transitions of the part of the sample in contact with the probe. This technique is a

Failure Forecasting in Triaxially Stressed Sandstones

Science.gov (United States)

Crippen, A.; Bell, A. F.; Curtis, A.; Main, I. G.

2017-12-01

Precursory signals to fracturing events have been observed to follow power-law accelerations in spatial, temporal, and size distributions leading up to catastrophic failure. In previous studies this behavior was modeled using Voight's relation of a geophysical precursor in order to perform `hindcasts' by solving for failure onset time. However, performing this analysis in retrospect creates a bias, as we know an event happened, when it happened, and we can search data for precursors accordingly. We aim to remove this retrospective bias, thereby allowing us to make failure forecasts in real-time in a rock deformation laboratory. We triaxially compressed water-saturated 100 mm sandstone cores (Pc= 25MPa, Pp = 5MPa, σ = 1.0E-5 s-1) to the point of failure while monitoring strain rate, differential stress, AEs, and continuous waveform data. Here we compare the current `hindcast` methods on synthetic and our real laboratory data. We then apply these techniques to increasing fractions of the data sets to observe the evolution of the failure forecast time with precursory data. We discuss these results as well as our plan to mitigate false positives and minimize errors for real-time application. Real-time failure forecasting could revolutionize the field of hazard mitigation of brittle failure processes by allowing non-invasive monitoring of civil structures, volcanoes, and possibly fault zones.

Experimental investigation of radiation effect on human thermal comfort by Taguchi method

International Nuclear Information System (INIS)

Arslanoglu, Nurullah; Yigit, Abdulvahap

2016-01-01

Highlights: • Radiation heat flux from lighting lamps on human thermal comfort is studied. • The effect of posture position on thermal comfort is investigated. • The effect of clothing color on thermal comfort is examined. • Radiation heat flux from halogen reflector lamp increase skin temperature more. • Posture position effect on thermal comfort is less than the other parameters. - Abstract: In this study, the effect of radiation heat flux of lighting lamps on human thermal comfort was investigated by using Taguchi method. In addition, at indoor conditions, clothing color and posture position under the radiation effect on thermal comfort were also investigated. For this purpose, experiments were performed in an air conditioned laboratory room in summer and autumn seasons. The amount of temperature rise on the back was considered as performance parameter. An L8 orthogonal array was selected as an experimental plan for the third parameters mentioned above for summer and autumn seasons. The results were analyzed for the optimum conditions using signal-to-noise (S/N) ratio and ANOVA method. The optimum results were found to be clear halogen lamp as lighting lamp, white as t-shirt color, standing as posture position, in summer season. The optimum levels of the lighting lamp, t-shirt color and posture position were found to be clear halogen lamp, white, sitting in autumn season, respectively.

Comparison of the properties of various optically stimulated luminescence signals from potassium feldspar

International Nuclear Information System (INIS)

Fu Xiao; Zhang Jiafu; Zhou Liping

2012-01-01

Various optically stimulated luminescence signals from K-feldspar have been used to determine the equivalent doses of sediment samples. Understanding the properties of these optical signals is critical to evaluate their applicability and limitations to optical dating. In this paper, some properties of IRSL, post-IR OSL and post-IR IRSL signals (detected in the UV region using U-340 filters) from a museum sample of K-feldspar were investigated by analyzing the relationships between optical and TL signals, and the effect of optical bleaching and heating on optical signals. The trap parameters of the different optical signals were calculated using the pulse annealing method. The results show that this sample exhibits two regenerated TL peaks at ∼140 and ∼330 °C. Corresponding to the low temperature TL peak, the OSL and post-IR OSL signals appear to be more associated with lower temperature TL than the IRSL signal measured at 50 °C. Corresponding to the high temperature TL peak, the post-IR IRSL signals mainly originate from the more thermally stable traps associated with the high temperature TL, compared with the IRSL and post-IR OSL signals. However, the post-IR IRSL 225°C signal is shown to be hard to be bleached by blue light and simulated sunlight, compared with the IRSL 50°C and low temperature post-IR IRSL signals. The implication for optical dating is that the elevated temperature post-IR IRSL signals can be preferentially applied over other signals from K-feldspar, but it is desirable that the effectiveness of the pre-depositional zeroing of these signals is assessed.

Studies of planetary boundary layer by infrared thermal imagery

Energy Technology Data Exchange (ETDEWEB)

Albina, Bogdan; Dimitriu, Dan Gheorghe, E-mail: dimitriu@uaic.ro; Gurlui, Silviu Octavian, E-mail: dimitriu@uaic.ro [Alexandru Ioan Cuza University of Iasi, Faculty of Physics, Atmosphere Optics, Spectroscopy and Lasers Laboratory, 11 Carol I Blvd., 700506 Iasi (Romania); Cazacu, Marius Mihai [Alexandru Ioan Cuza University of Iasi, Faculty of Physics, Atmosphere Optics, Spectroscopy and Lasers Laboratory, 11 Carol I Blvd., 700506 Iasi, Romania and Department of Physics, Gheorghe Asachi Technical University of Iasi, 59A Mangeron Blvd., 700 (Romania); Timofte, Adrian [Alexandru Ioan Cuza University of Iasi, Faculty of Physics, Atmosphere Optics, Spectroscopy and Lasers Laboratory, 11 Carol I Blvd., 700506 Iasi, Romania and National Meteorological Administration, Regional Forecast Center Bacau, 1 Cuza Voda Str., 60 (Romania)

2014-11-24

The IR camera is a relatively novel device for remote sensing of atmospheric thermal processes from the Planetary Boundary Layer (PBL) based on measurements of the infrared radiation. Infrared radiation is energy radiated by the motion of atoms and molecules on the surface of aerosols, when their temperature is more than absolute zero. The IR camera measures directly the intensity of radiation emitted by aerosols which is converted by an imaging sensor into an electric signal, resulting a thermal image. Every image pixel that corresponds to a specific radiance is pre-processed to identify the brightness temperature. The thermal infrared imaging radiometer used in this study, NicAir, is a precision radiometer developed by Prata et al. The device was calibrated for the temperature range of 270–320 K and using a calibration table along with image processing software, important information about variations in temperature can be extracted from acquired IR images. The PBL is the lowest layer of the troposphere where the atmosphere interacts with the ground surfaces. The importance of PBL lies in the fact that it provides a finite but varying volume in which pollutants can disperse. The aim of this paper is to analyze the PBL altitude and thickness variations over Iasi region using the IR imaging camera as well as its behavior from day to night and thermal processes occurring in PBL.

Thermal diagnostic of the optical window on board LISA Pathfinder

International Nuclear Information System (INIS)

Nofrarias, M; MarIn, A F GarcIa; Lobo, A; Heinzel, G; Ramos-Castro, J; Sanjuan, J; Danzmann, K

2007-01-01

Vacuum conditions inside the LTP gravitational reference sensor must be under 10 -5 Pa, a rather demanding requirement. The optical window (OW) is an interface which seals the vacuum enclosure and, at the same time, lets the laser beam go through for interferometric metrology with the test masses. The OW is a plane-parallel plate clamped in a titanium flange, and is considerably sensitive to thermal and stress fluctuations. It is critical for the required precision measurements, hence its temperature will be carefully monitored in flight. This paper reports on the results of a series of OW characterization laboratory runs, intended to study its response to selected thermal signals, as well as their fit to numerical models, and the meaning of the latter. We find that a single-pole ARMA transfer function provides a consistent approximation to the OW response to thermal excitations, and derive a relationship with the physical processes taking place in the OW. We also show how the system noise reduction can be accomplished by means of that transfer function

Retroactive signaling in short signaling pathways.

Directory of Open Access Journals (Sweden)

Jacques-Alexandre Sepulchre

Full Text Available In biochemical signaling pathways without explicit feedback connections, the core signal transduction is usually described as a one-way communication, going from upstream to downstream in a feedforward chain or network of covalent modification cycles. In this paper we explore the possibility of a new type of signaling called retroactive signaling, offered by the recently demonstrated property of retroactivity in signaling cascades. The possibility of retroactive signaling is analysed in the simplest case of the stationary states of a bicyclic cascade of signaling cycles. In this case, we work out the conditions for which variables of the upstream cycle are affected by a change of the total amount of protein in the downstream cycle, or by a variation of the phosphatase deactivating the same protein. Particularly, we predict the characteristic ranges of the downstream protein, or of the downstream phosphatase, for which a retroactive effect can be observed on the upstream cycle variables. Next, we extend the possibility of retroactive signaling in short but nonlinear signaling pathways involving a few covalent modification cycles.

Effects of Starvation and Thermal Stress on the Thermal Tolerance of Silkworm, Bombyx mori: Existence of Trade-offs and Cross-Tolerances.

Science.gov (United States)

Mir, A H; Qamar, A

2017-09-27

Organisms, in nature, are often subjected to multiple stressors, both biotic and abiotic. Temperature and starvation are among the main stressors experienced by organisms in their developmental cycle and the responses to these stressors may share signaling pathways, which affects the way these responses are manifested. Temperature is a major factor governing the performance of ectothermic organisms in ecosystems worldwide and, therefore, the thermal tolerance is a central issue in the thermobiology of these organisms. Here, we investigated the effects of starvation as well as mild heat and cold shocks on the thermal tolerance of the larvae of silkworm, Bombyx mori (Linnaeus). Starvation acted as a meaningful or positive stressor as it improved cold tolerance, measured as chill coma recovery time (CCRT), but, at the same time, it acted as a negative stressor and impaired the heat tolerance, measured as heat knockdown time (HKT). In the case of heat tolerance, starvation negated the positive effects of both mild cold as well as mild heat shocks and thus indicated the existence of trade-off between these stressors. Both mild heat and cold shocks improved the thermal tolerance, but the effects were more prominent when the indices were measured in response to a stressor of same type, i.e., a mild cold shock improved the cold tolerance more than the heat tolerance and vice versa. This improvement in thermal tolerance by both mild heat as well as cold shocks indicated the possibility of cross-tolerance between these stressors.

Direct observation of the thermal demagnetization of magnetic vortex structures in nonideal magnetite recorders

DEFF Research Database (Denmark)

Almeida, Trevor P.; Muxworthy, Adrian R.; Kovács, András

2016-01-01

The thermal demagnetization of pseudo-single-domain (PSD) magnetite (Fe3O4) particles, which govern the magnetic signal in many igneous rocks, is examined using off-axis electron holography. Visualization of a vortex structure held by an individual Fe3O4 particle (~250nm in diameter) during in situ...

Electropyroelectric technique for measurement of the thermal effusivity of liquids

Energy Technology Data Exchange (ETDEWEB)

Ivanov, R; Moreno, I; Araujo, C [Facultad de Fisica, Universidad Autonoma de Zacatecas, Calz. Solidaridad Esquina Paseo de la Bufa s/n, C. P. 98060, Zacatecas, Zac. (Mexico); Marin, E, E-mail: emarin63@yahoo.e, E-mail: emarinm@ipn.m [Centro de Investigacion en Ciencia Aplicada y TecnologIa Avanzada, Instituto Politecnico Nacional, LegarIa 694, Colonia Irrigacion, C. P. 11500, Mexico D. F. (Mexico)

2010-06-09

The photopyroelectric method has been recognized as a reliable and useful tool for the measurement of the thermal properties of condensed matter samples. Usually the photothermal signal is generated using intensity modulated light beams, whose amplitudes are difficult to maintain stable. In this paper we describe a variant of this technique that uses amplitude modulated electrical current as excitation source, via Joule heating of the metal contact on one side of the pyroelectric sensor. The possibilities of this method, called by us the electropyroelectric technique, for thermal effusivity measurements of liquid samples are shown using test samples of distilled water, ethanol and glycerine. The results obtained for this parameter agree well with the values reported in the literature. Our measurement uncertainties are about 3%, a fact that opens several possible applications.

Electropyroelectric technique for measurement of the thermal effusivity of liquids

International Nuclear Information System (INIS)

Ivanov, R; Moreno, I; Araujo, C; Marin, E

2010-01-01

The photopyroelectric method has been recognized as a reliable and useful tool for the measurement of the thermal properties of condensed matter samples. Usually the photothermal signal is generated using intensity modulated light beams, whose amplitudes are difficult to maintain stable. In this paper we describe a variant of this technique that uses amplitude modulated electrical current as excitation source, via Joule heating of the metal contact on one side of the pyroelectric sensor. The possibilities of this method, called by us the electropyroelectric technique, for thermal effusivity measurements of liquid samples are shown using test samples of distilled water, ethanol and glycerine. The results obtained for this parameter agree well with the values reported in the literature. Our measurement uncertainties are about 3%, a fact that opens several possible applications.

Establishing the thermal threshold of the tropical mussel Perna viridis in the face of global warming.

Science.gov (United States)

Goh, B P L; Lai, C H

2014-08-30

With increasing recognition that maximum oxygen demand is the unifying limit in tolerance, the first line of thermal sensitivity is, as a corollary, due to capacity limitations at a high level of organisational complexity before individual, molecular or membrane functions become disturbed. In this study the tropical mussel Perna viridis were subjected to temperature change of 0.4 °C per hour from ambient to 8-36 °C. By comparing thermal mortality against biochemical indices (hsp70, gluthathione), physiological indices (glycogen, FRAP, NRRT) and behavioural indices (clearance rate), a hierarchy of thermal tolerance was therein elucidated, ranging from systemic to cellular to molecular levels. Generally, while biochemical indices indicated a stress signal much earlier than the more integrated behavioural indices, failure of the latter (indicating a tolerance limit and transition to pejus state) occurred much earlier than the other indices tending towards thermal extremities at both ends of the thermal spectrum. Copyright © 2013 Elsevier Ltd. All rights reserved.

Thermalization calorimetry: A simple method for investigating glass transition and crystallization of supercooled liquids

Directory of Open Access Journals (Sweden)

Bo Jakobsen

2016-05-01

Full Text Available We present a simple method for fast and cheap thermal analysis on supercooled glass-forming liquids. This “Thermalization Calorimetry” technique is based on monitoring the temperature and its rate of change during heating or cooling of a sample for which the thermal power input comes from heat conduction through an insulating material, i.e., is proportional to the temperature difference between sample and surroundings. The monitored signal reflects the sample’s specific heat and is sensitive to exo- and endothermic processes. The technique is useful for studying supercooled liquids and their crystallization, e.g., for locating the glass transition and melting point(s, as well as for investigating the stability against crystallization and estimating the relative change in specific heat between the solid and liquid phases at the glass transition.

Thermally joining and/or coating or thermally separating the workpieces having heat-sensitive coating, comprises restoring coating by thermally coating the coating material after thermally joining and/or coating or thermally separating

OpenAIRE

Riedel, Frank; Winkelmann, Ralf; Puschmann, Markus

2011-01-01

The method for thermally joining and/or coating or thermally separating the workpieces (1), which have a heat-sensitive coating (2), comprises restoring the coating by thermally coating a coating material (3) after thermally joining and/or coating or thermally separating the workpieces. A part of the thermal energy introduced in the workpiece for joining and/or coating or separating or in the workpieces is used for thermally coating the coating material. Two workpieces are welded or soldered ...

Possible association between some geomagnetic anomalies and Vrancea (Romania) significant earthquakes occurred in the year 2005

International Nuclear Information System (INIS)

Enescu, D.

2006-01-01

The association between geoelectromagnetic anomalies and Vrancea earthquakes of moment magnitudes 3.7 ≤ M W ≤ 5 was first proved by Enescu et al. in some earlier papers. This finding was extended by Enescu to a broader magnitude range 3.7 ≤ M W ≤ 6.3. That study proved that observable precursory anomalies in the geomagnetic impedance have preceded all Vrancea earthquakes of moment magnitudes M W ≥ 4.0 occurring in 2004 year. A similar study is made in the present paper for data recorded in 2005 year. This study confirms the main result obtained in the earlier papers, namely that the great majority of Vrancea earthquakes of magnitudes higher than 4 are associated with precursory anomalies in the geomagnetic impedance. It also seems that neither the precursor time or the amplitude of the precursory magnetic anomaly can be linked reliably with the magnitude of the anticipated earthquake. (author)

Characterization of nitride hole lateral transport in a charge trap flash memory by using a random telegraph signal method

Science.gov (United States)

Liu, Yu-Heng; Jiang, Cheng-Min; Lin, Hsiao-Yi; Wang, Tahui; Tsai, Wen-Jer; Lu, Tao-Cheng; Chen, Kuang-Chao; Lu, Chih-Yuan

2017-07-01

We use a random telegraph signal method to investigate nitride trapped hole lateral transport in a charge trap flash memory. The concept of this method is to utilize an interface oxide trap and its associated random telegraph signal as an internal probe to detect a local channel potential change resulting from nitride charge lateral movement. We apply different voltages to the drain of a memory cell and vary a bake temperature in retention to study the electric field and temperature dependence of hole lateral movement in a nitride. Thermal energy absorption by trapped holes in lateral transport is characterized. Mechanisms of hole lateral transport in retention are investigated. From the measured and modeled results, we find that thermally assisted trap-to-band tunneling is a major trapped hole emission mechanism in nitride hole lateral transport.

Detection of AE signals from a HTS tape during quenching in a solid cryogen-cooling system

International Nuclear Information System (INIS)

Kim, K.J.; Song, J.B.; Kim, J.H.; Lee, J.H.; Kim, H.M.; Kim, W.S.; Na, J.B.; Ko, T.K.; Lee, H.G.

2010-01-01

The acoustic emission (AE) technique is suitable for detecting the presence of thermal and mechanical stress in superconductors, which have adverse effects on the stability of their application systems. However, the detection of AE signals from a HTS tape in a bath of liquid cryogen (such as liquid nitrogen, LN 2 ) has not been reported because of its low signal to noise ratio due to the noise from the boiling liquid cryogen. In order to obtain the AE signals from the HTS tapes during quenching, this study carried out repetitive quench tests for YBCO coated conductor (CC) tapes in a cooling system using solid nitrogen (SN 2 ). This paper examined the performance of the AE sensor in terms of the amplitudes of the AE signals in the SN 2 cooling system.

No Effect of TETRA Hand Portable Transmission Signals on Human Cognitive Function and Symptoms

DEFF Research Database (Denmark)

Riddervold, Ingunn Skogstad; Kjærgaard, Søren K.; Pedersen, Gert F.

2010-01-01

Current radio frequency radiation exposure guidelines rest on well-established thermal effects. However, recent research into analogue and digital transmission fields at levels covered by the exposure guidelines has indicated possible detrimental effects on human cognitive performance. To investi......Current radio frequency radiation exposure guidelines rest on well-established thermal effects. However, recent research into analogue and digital transmission fields at levels covered by the exposure guidelines has indicated possible detrimental effects on human cognitive performance....... To investigate this, we conducted a controlled climate chamber study of possible changes in cognitive performance in healthy volunteers exposed to transmission signals from TETRA hand portables (TETRA handsets). The trial deployed a balanced, randomized, double-blinded cross-over design. Performance on different...... paper-and-pencil, auditory and computer-based cognitive tasks was monitored in 53 male volunteers (mean age 36.41 years, SD 8.35) during 45-min exposure to a TETRA handset and sham control signals remotely controlled from a laboratory more than 100 km away. The main cognitive outcome was the Trail...

A Lumped Thermal Model Including Thermal Coupling and Thermal Boundary Conditions for High Power IGBT Modules

DEFF Research Database (Denmark)

Bahman, Amir Sajjad; Ma, Ke; Blaabjerg, Frede

2018-01-01

Detailed thermal dynamics of high power IGBT modules are important information for the reliability analysis and thermal design of power electronic systems. However, the existing thermal models have their limits to correctly predict these complicated thermal behavior in the IGBTs: The typically used...... thermal model based on one-dimensional RC lumps have limits to provide temperature distributions inside the device, moreover some variable factors in the real-field applications like the cooling and heating conditions of the converter cannot be adapted. On the other hand, the more advanced three......-dimensional thermal models based on Finite Element Method (FEM) need massive computations, which make the long-term thermal dynamics difficult to calculate. In this paper, a new lumped three-dimensional thermal model is proposed, which can be easily characterized from FEM simulations and can acquire the critical...

The influence of temperature calibration on the OC–EC results from a dual-optics thermal carbon analyzer

Science.gov (United States)

The Sunset Laboratory Dual-Optical Carbonaceous Analyzer that simultaneously measures transmission and reflectance signals is widely used in thermal-optical analysis of particulate matter samples. Most often this instrument is used to measure total carbon (TC), organic carbon (O...

Thermal precipitation fluorescence assay for protein stability screening.

Science.gov (United States)

Fan, Junping; Huang, Bo; Wang, Xianping; Zhang, Xuejun C

2011-09-01

A simple and reliable method of protein stability assessment is desirable for high throughput expression screening of recombinant proteins. Here we described an assay termed thermal precipitation fluorescence (TPF) which can be used to compare thermal stabilities of recombinant protein samples directly from cell lysate supernatants. In this assay, target membrane proteins are expressed as recombinant fusions with a green fluorescence protein tag and solubilized with detergent, and the fluorescence signals are used to report the quantity of the fusion proteins in the soluble fraction of the cell lysate. After applying a heat shock, insoluble protein aggregates are removed by centrifugation. Subsequently, the amount of remaining protein in the supernatant is quantified by in-gel fluorescence analysis and compared to samples without a heat shock treatment. Over 60 recombinant membrane proteins from Escherichia coli were subject to this screening in the presence and absence of a few commonly used detergents, and the results were analyzed. Because no sophisticated protein purification is required, this TPF technique is suitable to high throughput expression screening of recombinant membrane proteins as well as soluble ones and can be used to prioritize target proteins based on their thermal stabilities for subsequent large scale expression and structural studies. Copyright © 2011 Elsevier Inc. All rights reserved.

Thermal cycling fatigue of organic thermal interface materials using a thermal-displacement measurement technique

Science.gov (United States)

Steill, Jason Scott

The long term reliability of polymer-based thermal interface materials (TIM) is essential for modern electronic packages which require robust thermal management. The challenge for today's materials scientists and engineers is to maximize the heat flow from integrated circuits through a TIM and out the heat sink. Thermal cycling of the electronic package and non-uniformity in the heat flux with respect to the plan area can lead to void formation and delamination which re-introduces inefficient heat transfer. Measurement and understanding at the nano-scale is essential for TIM development. Finding and documenting the evolution of the defects is dependent upon a full understanding of the thermal probes response to changing environmental conditions and the effects of probe usage. The response of the thermal-displacement measurement technique was dominated by changes to the environment. Accurate measurement of the thermal performance was hindered by the inability to create a model system and control the operating conditions. This research highlights the need for continued study into the probe's thermal and mechanical response using tightly controlled test conditions.

The impact of thermal wave characteristics on thermal dose distribution during thermal therapy: A numerical study

International Nuclear Information System (INIS)

Shih, T.-C.; Kou, H.-S.; Liauh, C.-T.; Lin, W.-L.

2005-01-01

The aim of this study was to investigate the effects of the propagation speed of a thermal wave in terms of the thermal relaxation time on the temperature/thermal dose distributions in living tissue during thermal therapies. The temperature field in tissue was solved by the finite difference method, and the thermal dose was calculated from the formulation proposed by Sapareto and Dewey [Int. J. Radiat. Oncol. Biol. Phys. 10, 787-800 (1984)]. Under the same total deposited energy, for a rapid heating process the time lagging behavior of the peak temperature became pronounced and the level of the peak temperature was decreased with increasing the thermal relaxation time. When the heating duration was longer than the thermal relaxation time of tissues, there was no significant difference between the thermal dose distributions with/without considering the effect of the thermal relaxation time. In other words, when the heating duration is comparable to or shorter than the thermal relaxation time of tissue, the results of the wave bioheat transfer equation (WBHTE) are fully different from that of the Pennes' bioheat transfer equation (PBHTE). Besides, for a rapid heating process the dimension of thermal lesion was still significantly affected by perfusion, because this is what is predicted by the WBHTE but not by the PBHTE, i.e., the wave feature of the temperature field cannot fully be predicted by the PBHTE

BOLD fMRI of C-Fiber Mediated Nociceptive Processing in Mouse Brain in Response to Thermal Stimulation of the Forepaws.

Directory of Open Access Journals (Sweden)

Simone C Bosshard

Full Text Available Functional magnetic resonance imaging (fMRI in rodents enables non-invasive studies of brain function in response to peripheral input or at rest. In this study we describe a thermal stimulation paradigm using infrared laser diodes to apply noxious heat to the forepaw of mice in order to study nociceptive processing. Stimulation at 45 and 46°C led to robust BOLD signal changes in various brain structures including the somatosensory cortices and the thalamus. The BOLD signal amplitude scaled with the temperature applied but not with the area irradiated by the laser beam. To demonstrate the specificity of the paradigm for assessing nociceptive signaling we administered the quaternary lidocaine derivative QX-314 to the forepaws, which due to its positive charge cannot readily cross biological membranes. However, upon activation of TRPV1 channels following the administration of capsaicin the BOLD signal was largely abolished, indicative of a selective block of the C-fiber nociceptors due to QX-314 having entered the cells via the now open TRPV1 channels. This demonstrates that the cerebral BOLD response to thermal noxious paw stimulation is specifically mediated by C-fibers.

Thermal signature measurements for ammonium nitrate/fuel mixtures by laser heating

International Nuclear Information System (INIS)

Nazarian, Ashot; Presser, Cary

2016-01-01

Highlights: • LDTR is a useful diagnostic for characterizing AN/fuel mixture thermochemical behavior. • Each AN/fuel mixture thermal signature was different. • AN/fuel mixture signature features were defined by the individual constituents. • Baseline signatures changed after an experiment. - Abstract: Measurements were carried out to obtain thermal signatures of several ammonium nitrate/fuel (ANF) mixtures, using a laser-heating technique referred to as the laser-driven thermal reactor (LDTR). The mixtures were ammonium nitrate (AN)/kerosene, AN/ethylene glycol, AN/paraffin wax, AN/petroleum jelly, AN/confectioner's sugar, AN/cellulose (tissue paper), nitromethane/cellulose, nitrobenzene/cellulose, AN/cellulose/nitromethane, AN/cellulose/nitrobenzene. These mixtures were also compared with AN/nitromethane and AN/diesel fuel oil, obtained from an earlier investigation. Thermograms for the mixtures, as well as individual constituents, were compared to better understand how sample thermal signature changes with mixture composition. This is the first step in development of a thermal-signature database, to be used along with other signature databases, to improve identification of energetic substances of unknown composition. The results indicated that each individual thermal signature was associated unambiguously with a particular mixture composition. The signature features of a particular mixture were shaped by the individual constituent signatures. It was also uncovered that the baseline signature was modified after an experiment due to coating of unreacted residue on the substrate surface and a change in the reactor sphere oxide layer. Thus, care was required to pre-oxidize the sphere prior to an experiment. A minimum sample mass (which was dependent on composition) was required to detect the signature characteristics. Increased laser power served to magnify signal strength while preserving the signature features. For the mixtures examined, the thermal

Numerical analysis of thermal response tests with a groundwater flow and heat transfer model

Energy Technology Data Exchange (ETDEWEB)

Raymond, J.; Therrien, R. [Departement de Geologie et de Genie Ggeologique, Universite Laval, 1065 avenue de la medecine, Quebec (Qc) G1V 0A6 (Canada); Gosselin, L. [Departement de Genie Mecanique, Universite Laval, 1065 avenue de la medecine, Quebec (Qc) G1V 0A6 (Canada); Lefebvre, R. [Institut National de la Recherche Scientifique, Centre Eau Terre Environnement, 490 de la Couronne, Quebec (Qc) G1K 9A9 (Canada)

2011-01-15

The Kelvin line-source equation, used to analyze thermal response tests, describes conductive heat transfer in a homogeneous medium with a constant temperature at infinite boundaries. The equation is based on assumptions that are valid for most ground-coupled heat pump environments with the exception of geological settings where there is significant groundwater flow, heterogeneous distribution of subsurface properties, a high geothermal gradient or significant atmospheric temperature variations. To address these specific cases, an alternative method to analyze thermal response tests was developed. The method consists in estimating parameters by reproducing the output temperature signal recorded during a test with a numerical groundwater flow and heat transfer model. The input temperature signal is specified at the entrance of the ground heat exchanger, where flow and heat transfer are computed in 2D planes representing piping and whose contributions are added to the 3D porous medium. Results obtained with this method are compared to those of the line-source model for a test performed under standard conditions. A second test conducted in waste rock at the South Dump of the Doyon Mine, where conditions deviate from the line-source assumptions, is analyzed with the numerical model. The numerical model improves the representation of the physical processes involved during a thermal response test compared to the line-source equation, without a significant increase in computational time. (author)

Study on thermal wave based on the thermal mass theory

Institute of Scientific and Technical Information of China (English)

无

2009-01-01

The conservation equations for heat conduction are established based on the concept of thermal mass.We obtain a general heat conduction law which takes into account the spatial and temporal inertia of thermal mass.The general law introduces a damped thermal wave equation.It reduces to the well-known CV model when the spatial inertia of heat flux and temperature and the temporal inertia of temperature are neglected,which indicates that the CV model only considers the temporal inertia of heat flux.Numerical simulations on the propagation and superposition of thermal waves show that for small thermal perturbation the CV model agrees with the thermal wave equation based on the thermal mass theory.For larger thermal perturbation,however,the physically impossible phenomenon pre-dicted by CV model,i.e.the negative temperature induced by the thermal wave superposition,is eliminated by the general heat conduction law,which demonstrates that the present heat conduction law based on the thermal mass theory is more reasonable.

Study on thermal wave based on the thermal mass theory

Institute of Scientific and Technical Information of China (English)

HU RuiFeng; CAO BingYang

2009-01-01

The conservation equations for heat conduction are established based on the concept of thermal mass. We obtain a general heat conduction law which takes into account the spatial and temporal inertia of thermal mass. The general law introduces a damped thermal wave equation. It reduces to the well-known CV model when the spatial inertia of heat flux and temperature and the temporal inertia of temperature are neglected, which indicates that the CV model only considers the temporal inertia of heat flux. Numerical simulations on the propagation and superposition of thermal waves show that for small thermal perturbation the CV model agrees with the thermal wave equation based on the thermal mass theory. For larger thermal perturbation, however, the physically impossible phenomenon pre-dicted by CV model, i.e. the negative temperature induced by the thermal wave superposition, is eliminated by the general heat conduction law, which demonstrates that the present heat conduction law based on the thermal mass theory is more reasonable.

Detection of thermally grown oxides in thermal barrier coatings by nondestructive evaluation

Science.gov (United States)

Fahr, A.; Rogé, B.; Thornton, J.

2006-03-01

The thermal-barrier coatings (TBC) sprayed on hot-section components of aircraft turbine engines commonly consist of a partially stabilized zirconia top-coat and an intermediate bond-coat applied on the metallic substrate. The bond-coat is made of an aluminide alloy that at high engine temperatures forms thermally grown oxides (TGO). Although formation of a thin layer of aluminum oxide at the interface between the ceramic top-coat and the bond-coat has the beneficial effect of protecting the metallic substrate from hot gases, oxide formation at splat boundaries or pores within the bond-coat is a source of weakness. In this study, plasma-sprayed TBC specimens are manufactured from two types of bond-coat powders and exposed to elevated temperatures to form oxides at the ceramic-bond-coat boundary and within the bond-coat. The specimens are then tested using nondestructive evaluation (NDE) and destructive metallography and compared with the as-manufactured samples. The objective is to determine if NDE can identify the oxidation within the bond-coat and give indication of its severity. While ultrasonic testing can provide some indication of the degree of bond-coat oxidation, the eddy current (EC) technique clearly identifies severe oxide formation within the bond-coat. Imaging of the EC signals as the function of probe location provides information on the spatial variations in the degree of oxidation, and thereby identifies which components or areas are prone to premature damage.

Standoff laser-induced thermal emission of explosives

Science.gov (United States)

Galán-Freyle, Nataly Y.; Pacheco-Londoño, Leonardo C.; Figueroa-Navedo, Amanda; Hernandez-Rivera, Samuel P.

2013-05-01

A laser mediated methodology for remote thermal excitation of analytes followed by standoff IR detection is proposed. The goal of this study was to determine the feasibility of using laser induced thermal emission (LITE) from vibrationally excited explosives residues deposited on surfaces to detect explosives remotely. Telescope based FT-IR spectral measurements were carried out to examine substrates containing trace amounts of threat compounds used in explosive devices. The highly energetic materials (HEM) used were PETN, TATP, RDX, TNT, DNT and ammonium nitrate with concentrations from 5 to 200 μg/cm2. Target substrates of various thicknesses were remotely heated using a high power CO2 laser, and their mid-infrared (MIR) thermally stimulated emission spectra were recorded. The telescope was configured from reflective optical elements in order to minimize emission losses in the MIR frequencies and to provide optimum overall performance. Spectral replicas were acquired at a distance of 4 m with an FT-IR interferometer at 4 cm- 1 resolution and 10 scans. Laser power was varied from 4-36 W at radiation exposure times of 10, 20, 30 and 60 s. CO2 laser powers were adjusted to improve the detection and identification of the HEM samples. The advantages of increasing the thermal emission were easily observed in the results. Signal intensities were proportional to the thickness of the coated surface (a function of the surface concentration), as well as the laser power and laser exposure time. For samples of RDX and PETN, varying the power and time of induction of the laser, the calculated low limit of detections were 2 and 1 μg/cm2, respectively.

Thermal Signature Measurements for Ammonium Nitrate/Fuel Mixtures by Laser Heating.

Science.gov (United States)

Nazarian, Ashot; Presser, Cary

2016-01-10

Measurements were carried out to obtain thermal signatures of several ammonium nitrate/fuel (ANF) mixtures, using a laser-heating technique referred to as the laser-driven thermal reactor (LDTR). The mixtures were ammonium nitrate (AN)/kerosene, AN/ethylene glycol, AN/paraffin wax, AN/petroleum jelly, AN/confectioner's sugar, AN/cellulose (tissue paper), nitromethane/cellulose, nitrobenzene/cellulose, AN/cellulose/nitromethane, AN/cellulose/nitrobenzene. These mixtures were also compared with AN/nitromethane and AN/diesel fuel oil, obtained from an earlier investigation. Thermograms for the mixtures, as well as individual constituents, were compared to better understand how the sample thermal signature changes with mixture composition. This is the first step in development of a thermal-signature database, to be used along with other signature databases, to improve identification of energetic substances of unknown composition. The results indicated that each individual thermal signature was associated unambiguously with a particular mixture composition. The signature features of a particular mixture were shaped by the individual constituent signatures. It was also uncovered that the baseline signature was modified after an experiment due to coating of unreacted residue on the substrate surface and a change in the reactor sphere oxide layer. Thus, care was required to pre-oxidize the sphere prior to an experiment. A minimum sample mass (which was dependent on composition) was required to detect the signature characteristics. Increased laser power served to magnify signal strength while preserving the signature features. For the mixtures examined, the thermal response of each ANF mixture was found to be different, which was based on the mixture composition and the thermal behavior of each mixture constituent.

The biology of skin wetness perception and its implications in manual function and for reproducing complex somatosensory signals in neuroprosthetics

Science.gov (United States)

Ackerley, Rochelle

2017-01-01

Our perception of skin wetness is generated readily, yet humans have no known receptor (hygroreceptor) to signal this directly. It is easy to imagine the sensation of water running over our hands or the feel of rain on our skin. The synthetic sensation of wetness is thought to be produced from a combination of specific skin thermal and tactile inputs, registered through thermoreceptors and mechanoreceptors, respectively. The present review explores how thermal and tactile afference from the periphery can generate the percept of wetness centrally. We propose that the main signals include information about skin cooling, signaled primarily by thinly myelinated thermoreceptors, and rapid changes in touch, through fast-conducting, myelinated mechanoreceptors. Potential central sites for integration of these signals, and thus the perception of skin wetness, include the primary and secondary somatosensory cortices and the insula cortex. The interactions underlying these processes can also be modeled to aid in understanding and engineering the mechanisms. Furthermore, we discuss the role that sensing wetness could play in precision grip and the dexterous manipulation of objects. We expand on these lines of inquiry to the application of the knowledge in designing and creating skin sensory feedback in prosthetics. The addition of real-time, complex sensory signals would mark a significant advance in the use and incorporation of prosthetic body parts for amputees in everyday life. PMID:28123008

Thermal Diffusivity Measurements in Edible Oils using Transient Thermal Lens

Science.gov (United States)

Valdez, R. Carbajal.; Pérez, J. L. Jiménez.; Cruz-Orea, A.; Martín-Martínez, E. San.

2006-11-01

Time resolved thermal lens (TL) spectrometry is applied to the study of the thermal diffusivity of edible oils such as olive, and refined and thermally treated avocado oils. A two laser mismatched-mode experimental configuration was used, with a He Ne laser as a probe beam and an Ar+ laser as the excitation one. The characteristic time constant of the transient thermal lens was obtained by fitting the experimental data to the theoretical expression for a transient thermal lens. The results showed that virgin olive oil has a higher thermal diffusivity than for refined and thermally treated avocado oils. This measured thermal property may contribute to a better understanding of the quality of edible oils, which is very important in the food industry. The thermal diffusivity results for virgin olive oil, obtained from this technique, agree with those reported in the literature.

Thermal-mechanical deformation modelling of soft tissues for thermal ablation.

Science.gov (United States)

Li, Xin; Zhong, Yongmin; Jazar, Reza; Subic, Aleksandar

2014-01-01

Modeling of thermal-induced mechanical behaviors of soft tissues is of great importance for thermal ablation. This paper presents a method by integrating the heating process with thermal-induced mechanical deformations of soft tissues for simulation and analysis of the thermal ablation process. This method combines bio-heat transfer theories, constitutive elastic material law under thermal loads as well as non-rigid motion dynamics to predict and analyze thermal-mechanical deformations of soft tissues. The 3D governing equations of thermal-mechanical soft tissue deformation are discretized by using the finite difference scheme and are subsequently solved by numerical algorithms. Experimental results show that the proposed method can effectively predict the thermal-induced mechanical behaviors of soft tissues, and can be used for the thermal ablation therapy to effectively control the delivered heat energy for cancer treatment.

Revisiting the thermal effect on shock wave propagation in weakly ionized plasmas

International Nuclear Information System (INIS)

Zhou, Qianhong; Dong, Zhiwei; Yang, Wei

2016-01-01

Many researchers have investigated shock propagation in weakly ionized plasmas and observed the following anomalous effects: shock acceleration, shock recovery, shock weakening, shock spreading, and splitting. It was generally accepted that the thermal effect can explain most of the experimental results. However, little attention was paid to the shock recovery. In this paper, the shock wave propagation in weakly ionized plasmas is studied by fluid simulation. It is found that the shock acceleration, weakening, and splitting appear after it enters the plasma (thermal) region. The shock splits into two parts right after it leaves the thermal region. The distance between the splitted shocks keeps decreasing until they recover to one. This paper can explain a whole set of features of the shock wave propagation in weakly ionized plasmas. It is also found that both the shock curvature and the splitting present the same photoacoustic deflection (PAD) signals, so they cannot be distinguished by the PAD experiments.

Experimental electro-thermal method for nondestructively testing welds in stainless steel pipes

International Nuclear Information System (INIS)

Green, D.R.

1979-01-01

Welds in austenitic stainless steel pipes are notoriously difficult to nondestructively examine using conventional ultrasonic and eddy current methods. Survace irregularities and microscopic variations in magnetic permeability cause false eddy current signal variations. Ultrasonic methods have been developed which use computer processing of the data to overcome some of the problems. Electro-thermal nondestructive testing shows promise for detecting flaws that are difficult to detect using other NDT methods. Results of a project completed to develop and demonstrate the potential of an electro-thermal method for nondestructively testing stainless steel pipe welds are presented. Electro-thermal NDT uses a brief pulse of electrical current injected into the pipe. Defects at any depth within the weld cause small differences in surface electrical current distribution. These cause short-lived transient temperature differences on the pipe's surface that are mapped using an infrared scanning camera. Localized microstructural differences and normal surface roughness in the welds have little effect on the surface temperatures

Quantitative one-dimensional thermal-wave cavity measurements of fluid thermophysical properties through equivalence studies with three-dimensional geometries

International Nuclear Information System (INIS)

Matvienko, Anna; Mandelis, Andreas

2006-01-01

The thermal-wave field in a photopyroelectric thermal-wave cavity was calculated with two theoretical approaches: a computationally straightforward, conventional, one-dimensional approach and a three-dimensional experimentally more realistic approach. The calculations show that the dimensionality of the thermal-wave field in the cavity depends on the lateral heat transfer boundary conditions and the relation between the beam size of the laser impinging on the thermal-wave generating metallic film and the diameter of the film itself. The theoretical calculations and the experimental data on the photopyroelectric signal in the cavity were compared. The study resulted in identifying ranges of heat transfer rates, beam sizes, and cavity radii for which accurate quantitative measurements of the thermal diffusivity of intracavity fluids can be made within the far simpler, but only approximate, one-dimensional approach conventionally adopted by users of thermal-wave cavities. It was shown that the major parameters affecting the dimensionality of thermal-wave cavities are the laser beam spot size and the Biot number of the medium comprising the sidewalls of the (cylindrical) cavity

Determination of the ion thermal diffusivity from neutron emission profiles in decay

International Nuclear Information System (INIS)

Sasao, M.; Adams, J.M.; Conroy, S.; Jarvis, O.N.; Marcus, F.B.; Sadler, G.; Belle, P. van

1994-01-01

Spatial profiles of the neutron emission from deuterium plasmas are routinely obtained at the Joint European Torus (JET) using the line-integrated signals measured with a multichannel instrument. It is shown that the manner in which these profiles relax following the termination of strong heating with neutral beam injection (NBI) permits the local thermal diffusivity (χ i ) to be obtained with an accuracy of about 20%. (author)

Thermally induced structural modifications and O{sub 2} trapping in highly porous silica nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Alessi, A., E-mail: antonino.alessi@unipa.it; Agnello, S.; Iovino, G.; Buscarino, G.; Melodia, E.G.; Cannas, M.; Gelardi, F.M.

2014-12-15

In this work we investigate by Raman spectroscopy the effect of isochronal (2 h) thermal treatments in air in the temperature range 200–1000 °C of amorphous silicon dioxide porous nanoparticles with diameters ranging from 5 up to 15 nm and specific surface 590–690 m{sup 2}/g. Our results indicate that the amorphous structure changes similarly to other porous systems previously investigated, in fact superficial SiOH groups are removed, Si–O–Si linkages are created and the ring statistic is modified, furthermore these data evidence that the three membered rings do not contribute significantly to the Raman signal detected at about 495 cm{sup −1}. In addition, after annealing at 900 and 1000 °C we noted the appearance of the O{sub 2} emission at 1272 nm, absent in the not treated samples. The measure of the O{sub 2} emission has been combined with electron paramagnetic resonance measurements of the γ irradiation induced HO{sup ·}{sub 2} radicals to investigate the O{sub 2} content per mass unit of thin layers of silica. Our data reveal that the porous nanoparticles have a much lower ability to trap O{sub 2} molecules per mass units than nonporous silica supporting a model by which O{sub 2} trapping inside a surface layer of about 1 nm of silica is always limited. - Highlights: • O{sub 2} emission and HO{sup ·}{sub 2} electron paramagnetic resonance signals are investigated. • Silica surface ability to trap O{sub 2} molecules is explored by thermal treatments. • Raman study of thermally induced structural changes in porous silica nanoparticles. • Raman signal attributable to the three membered rings in silica.

The Swift BAT Perspective on Non-Thermal Emission in HIFLUGCS Galaxy Clusters

Science.gov (United States)

Wik, Daniel R.

2011-01-01

The search for diffuse non-thermal, inverse Compton (IC) emission from galaxy clusters at hard X-ray energies has been underway for many years, with most detections being either of low significance or controversial. Until recently, comprehensive surveys of hard X-ray emission from clusters were not possible; instead, individually proposed-for. long observations would be collated from the archive. With the advent of the Swift BAT all sky survey, any c1u,;ter's emission above 14 keV can be probed with nearly uniform sensitivity. which is comparable to that of RXTE, Beppo-SAX, and Suzaku with the 58-month version of the survey. In this work. we search for non-thermal excess emission above the exponentially decreasing, high energy thermal emission in the flux-limited HIFLUGCS sample. The BAT emission from many of the detected clusters is marginally extended; we are able to extract the total flux for these clusters using fiducial models for their spatial extent. To account for thermal emission at BAT energies, XMM-Newton EPIC spectra are extracted from coincident spatial regions so that both the thermal and non-thermal spectral components can be determined simultaneou,;ly in joint fits. We find marginally significant IC components in 6 clusters, though after closer inspection and consideration of systematic errors we are unable to claim a clear detection in any of them. The spectra of all clusters are also summed to enhance a cumulative non-thermal signal not quite detectable in individual clusters. After constructing a model based on single temperature

A predictive model for smart control of a domestic heat pump and thermal storage

NARCIS (Netherlands)

van Leeuwen, Richard Pieter; Gebhardt, I.; de Wit, J.B.; Smit, Gerardus Johannes Maria

The purpose of this paper is to develop and validate a predictive model of a thermal storage which is charged by a heat pump and used for domestic hot water supply. The model is used for smart grid control purposes and requires measurement signals of flow and temperature at the inlet and outlet of

Recoil Induced Room Temperature Stable Frenkel Pairs in a-Hafnium Upon Thermal Neutron Capture

Science.gov (United States)

Butz, Tilman; Das, Satyendra K.; Dey, Chandi C.; Ghoshal, Shamik

2013-11-01

Ultrapure hafnium metal (110 ppm zirconium) was neutron activated with a thermal neutron flux of 6:6 · 1012 cm-2s-1 in order to obtain 181Hf for subsequent time differential perturbed angular correlation (TDPAC) experiments using the nuclear probe 181Hf(β-) 181Ta. Apart from the expected nuclear quadrupole interaction (NQI) signal for a hexagonal close-packed (hcp) metal, three further discrete NQIs were observed with a few percent fraction each. The TDPAC spectra were recorded for up to 11 half lives with extreme statistical accuracy. The fitted parameters vary slightly within the temperature range between 248 K and 373 K. The signals corresponding to the three additional sites completely disappear after `annealing' at 453 K for one minute. Based on the symmetry of the additional NQIs and their temperature dependencies, they are tentatively attributed to Frenkel pairs produced by recoil due to the emission of a prompt 5:694 MeV -ray following thermal neutron capture and reported by the nuclear probe in three different positions. These Frenkel pairs are stable up to at least 373 K.

Thermal parameter identification for non-Fourier heat transfer from molecular dynamics

Science.gov (United States)

Singh, Amit; Tadmor, Ellad B.

2015-10-01

Fourier's law leads to a diffusive model of heat transfer in which a thermal signal propagates infinitely fast and the only material parameter is the thermal conductivity. In micro- and nano-scale systems, non-Fourier effects involving coupled diffusion and wavelike propagation of heat can become important. An extension of Fourier's law to account for such effects leads to a Jeffreys-type model for heat transfer with two relaxation times. We propose a new Thermal Parameter Identification (TPI) method for obtaining the Jeffreys-type thermal parameters from molecular dynamics simulations. The TPI method makes use of a nonlinear regression-based approach for obtaining the coefficients in analytical expressions for cosine and sine-weighted averages of temperature and heat flux over the length of the system. The method is applied to argon nanobeams over a range of temperature and system sizes. The results for thermal conductivity are found to be in good agreement with standard Green-Kubo and direct method calculations. The TPI method is more efficient for systems with high diffusivity and has the advantage, that unlike the direct method, it is free from the influence of thermostats. In addition, the method provides the thermal relaxation times for argon. Using the determined parameters, the Jeffreys-type model is able to reproduce the molecular dynamics results for a short-duration heat pulse where wavelike propagation of heat is observed thereby confirming the existence of second sound in argon. An implementation of the TPI method in MATLAB is available as part of the online supplementary material.

Thermal characterization of tubular SiC/SiC composite structures for nuclear applications

International Nuclear Information System (INIS)

Duquesne, Loys

2015-01-01

Researches on the development on SiCf/SiC refractory composites for generation IV nuclear fuel cladding led the CEA to focus on the thermal behavior of these materials. In particular, knowledge of the thermal properties is essential for designing the components. Regarding the development of the 'sandwich' cladding concept, for which the complexity and the geometry differ from the conventionally used flat tubes, usual measurement methods are unsuitable. This study reports on the characterization and modeling of the thermal behavior of these structures. The first part deals with the identification of the global thermal parameters for the different layers of a 'sandwich' cladding. For this purpose, a flash method is used and an experimental device suitable for tubular geometries was developed. A new estimation method based on the combination of both collected signals in front and rear faces allows the identification of the thermal diffusivity of tubular composites using infrared thermography. The second part focuses on a virtual material approach, established to describe the thermal behavior of a 'sandwich' cladding, starting from the measured properties of the elementary components (fibers and matrix). They are then used as input data for the heat transfer modeling. Confrontations between experimental measurements and numerical results finally allow us to understand the importance of the various key parameters governing the heat transfer. (author) [fr

Characteristics of thermally assisted magnetic recording in granular perpendicular media

International Nuclear Information System (INIS)

Shiino, Hirotaka; Kawana, Mayumi; Miyashita, Eiichi; Hayashi, Naoto; Watanabe, Sadayuki

2009-01-01

The effect of thermally assisted magnetic recording using granular perpendicular media with a single-pole-trimmed head has been investigated. A read/write experiment using a spin stand in which the media were heated by laser irradiation demonstrated that the track average amplitude strongly depends on both the position of the write head relative to the center of the laser spot in the down-track direction and on the laser power. Although the signal-to-noise ratio increased with the coercivity of the media, the increment was small; this is thought to be caused by an increase in the switching field distribution of the media with temperature. Our results suggest that the magnetic constant of the media must be optimized with respect to the temperature of writing in order for high-density thermally assisted magnetic recording to be realized

Local body cooling to improve sleep quality and thermal comfort in a hot environment.

Science.gov (United States)

Lan, L; Qian, X L; Lian, Z W; Lin, Y B

2018-01-01

The effects of local body cooling on thermal comfort and sleep quality in a hot environment were investigated in an experiment with 16 male subjects. Sleep quality was evaluated subjectively, using questionnaires completed in the morning, and objectively, by analysis of electroencephalogram (EEG) signals that were continuously monitored during the sleeping period. Compared with no cooling, the largest improvement in thermal comfort and sleep quality was observed when the back and head (neck) were both cooled at a room temperature of 32°C. Back cooling alone also improved thermal comfort and sleep quality, although the effects were less than when cooling both back and head (neck). Mean sleep efficiency was improved from 84.6% in the no cooling condition to 95.3% and 92.8%, respectively, in these conditions, indicating good sleep quality. Head (neck) cooling alone slightly improved thermal comfort and subjective sleep quality and increased Stage N3 sleep, but did not otherwise improve sleep quality. The results show that local cooling applied to large body sections (back and head) could effectively maintain good sleep and improve thermal comfort in a hot environment. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Real-time temperature feedback for nanoparticles based tumor thermal treatment (Conference Presentation)

Science.gov (United States)

Steinberg, Idan; Tamir, Gil; Gannot, Israel

2017-02-01

Systemic hyperthermia therapy exploits the fact that cancer cells are more sensitive to elevated temperatures than healthy tissue. Systemic application of hyperthermia externally usually leads to low efficiency treatment. Recently, our group and others have proposed an antibody conjugated magnetic nanoparticles (MNPs) approach to overcome the limitation of systemic hyperthermia. MNPs can bind specifically to the tumor sites, thus delivering internal highly effective targeted hyperthermia. However, such internal mechanism requires more complicated controls and monitoring. This current work presents a deep tissue temperature monitoring method to control hyperthermia effectiveness and minimize collateral damage to surrounding tissues. A low-frequency narrowband modulation of the RF field used for MNP heating leads to the generation of diffused thermal waves which propagate to the tissue surface and captured by a thermal camera. A Fourier domain, analytical heat transfer model is used for temperature monitoring algorithm. The ill-posed thermal inverse problem is solved efficiently by iterating over the source power until both the amplitude and phase match the recorded thermal image sequence. The narrow bandwidth thermal stimulation enables acquiring deep signals with high SNR. We show that thermal transverse resolution improves as the stimulation frequency increases even slightly above DC, enabling better heat source transverse separation and margin identification in the case of distributed tumors. These results can be used as a part of an overall image and treat system for efficient detection of tumors, manipulation of MNPs and monitoring MNP based hyperthermia.

Thermally Annealed Iron (Oxide) Thin Film on an Alumina Barrier Layer, by XPS

Energy Technology Data Exchange (ETDEWEB)

Madaan, Nitesh; Kanyal, Supriya S.; Jensen, David S.; Vail, Michael A.; Dadson, Andrew; Engelhard, Mark H.; Linford, Matthew R.

2013-09-06

Herein we show characterization of an Fe thin film on Al_2O_3 after thermal annealing under H_2 using Al Ka X-rays. The XPS survey spectrum, narrow Fe 2p scan, and valence band regions are presented. The survey spectrum shows aluminum signals due to exposure of the underlying Al_2O_3 film during Fe nanoparticle formation.

The 21-cm Signal from the cosmological epoch of recombination

Energy Technology Data Exchange (ETDEWEB)

Fialkov, A. [Departement de Physique, Ecole Normale Superieure, CNRS, 24 rue Lhomond, Paris, 75005 (France); Loeb, A., E-mail: anastasia.fialkov@phys.ens.fr, E-mail: aloeb@cfa.harvard.edu [Department of Astronomy, Harvard University, 60 Garden Street, MS-51, Cambridge, MA, 02138 (United States)

2013-11-01

The redshifted 21-cm emission by neutral hydrogen offers a unique tool for mapping structure formation in the early universe in three dimensions. Here we provide the first detailed calculation of the 21-cm emission signal during and after the epoch of hydrogen recombination in the redshift range of z ∼ 500–1,100, corresponding to observed wavelengths of 100–230 meters. The 21-cm line deviates from thermal equilibrium with the cosmic microwave background (CMB) due to the excess Lyα radiation from hydrogen and helium recombinations. The resulting 21-cm signal reaches a brightness temperature of a milli-Kelvin, orders of magnitude larger than previously estimated. Its detection by a future lunar or space-based observatory could improve dramatically the statistical constraints on the cosmological initial conditions compared to existing two-dimensional maps of the CMB anisotropies.

The 21-cm Signal from the cosmological epoch of recombination

International Nuclear Information System (INIS)

Fialkov, A.; Loeb, A.

2013-01-01

The redshifted 21-cm emission by neutral hydrogen offers a unique tool for mapping structure formation in the early universe in three dimensions. Here we provide the first detailed calculation of the 21-cm emission signal during and after the epoch of hydrogen recombination in the redshift range of z ∼ 500–1,100, corresponding to observed wavelengths of 100–230 meters. The 21-cm line deviates from thermal equilibrium with the cosmic microwave background (CMB) due to the excess Lyα radiation from hydrogen and helium recombinations. The resulting 21-cm signal reaches a brightness temperature of a milli-Kelvin, orders of magnitude larger than previously estimated. Its detection by a future lunar or space-based observatory could improve dramatically the statistical constraints on the cosmological initial conditions compared to existing two-dimensional maps of the CMB anisotropies

On the half-life of luminescence signals in dosimetric applications: A unified presentation

Science.gov (United States)

Pagonis, V.; Kitis, G.; Polymeris, G. S.

2018-06-01

Luminescence signals from natural and man-made materials are widely used in dosimetric and dating applications. In general, there are two types of half-lives of luminescence signals which are of importance to experimental and modeling work in this research area. The first type of half-life is the time required for the population of the trapped charge in a single trap to decay to half its initial value. The second type of half-life is the time required for the luminescence intensity to drop to half of its initial value. While there a handful of analytical expressions available in the literature for the first type of half-life, there are no corresponding analytical expressions for the second type. In this work new analytical expressions are derived for the half-life of luminescence signals during continuous wave optical stimulation luminescence (CW-OSL) or isothermal luminescence (ITL) experiments. The analytical expressions are derived for several commonly used luminescence models which are based on delocalized transitions involving the conduction band: first and second order kinetics, empirical general order kinetics (GOK), mixed order kinetics (MOK) and the one-trap one-recombination center (OTOR) model. In addition, half-life expressions are derived for a different type of luminescence model, which is based on localized transitions in a random distribution of charges. The new half-life expressions contain two parts. The first part is inversely proportional to the thermal or optical excitation rate, and depends on the experimental conditions and on the cross section of the relevant luminescence process. The second part is characteristic of the optical and/or thermal properties of the material, as expressed by the parameters in the model. A new simple and quick method for analyzing luminescence signals is developed, and examples are given of applying the new method to a variety of dosimetric materials. The new test allows quick determination of whether a set of

Application of FFTBM with signal mirroring to improve accuracy assessment of MELCOR code

International Nuclear Information System (INIS)

Saghafi, Mahdi; Ghofrani, Mohammad Bagher; D’Auria, Francesco

2016-01-01

Highlights: • FFTBM-SM is an improved Fast Fourier Transform Base Method by signal mirroring. • FFTBM-SM has been applied to accuracy assessment of MELCOR code predictions. • The case studied was Station Black-Out accident in PSB-VVER integral test facility. • FFTBM-SM eliminates fluctuations of accuracy indices when signals sharply change. • Accuracy assessment is performed in a more realistic and consistent way by FFTBM-SM. - Abstract: This paper deals with the application of Fast Fourier Transform Base Method (FFTBM) with signal mirroring (FFTBM-SM) to assess accuracy of MELCOR code. This provides deeper insights into how the accuracy of MELCOR code in predictions of thermal-hydraulic parameters varies during transients. The case studied was modeling of Station Black-Out (SBO) accident in PSB-VVER integral test facility by MELCOR code. The accuracy of this thermal-hydraulic modeling was previously quantified using original FFTBM in a few number of time-intervals, based on phenomenological windows of SBO accident. Accuracy indices calculated by original FFTBM in a series of time-intervals unreasonably fluctuate when the investigated signals sharply increase or decrease. In the current study, accuracy of MELCOR code is quantified using FFTBM-SM in a series of increasing time-intervals, and the results are compared to those with original FFTBM. Also, differences between the accuracy indices of original FFTBM and FFTBM-SM are investigated and correction factors calculated to eliminate unphysical effects in original FFTBM. The main findings are: (1) replacing limited number of phenomena-based time-intervals by a series of increasing time-intervals provides deeper insights about accuracy variation of the MELCOR calculations, and (2) application of FFTBM-SM for accuracy evaluation of the MELCOR predictions, provides more reliable results than original FFTBM by eliminating the fluctuations of accuracy indices when experimental signals sharply increase or

Application of FFTBM with signal mirroring to improve accuracy assessment of MELCOR code

Energy Technology Data Exchange (ETDEWEB)

Saghafi, Mahdi [Department of Energy Engineering, Sharif University of Technology, Azadi Avenue, Tehran (Iran, Islamic Republic of); Ghofrani, Mohammad Bagher, E-mail: ghofrani@sharif.edu [Department of Energy Engineering, Sharif University of Technology, Azadi Avenue, Tehran (Iran, Islamic Republic of); D’Auria, Francesco [San Piero a Grado Nuclear Research Group (GRNSPG), University of Pisa, Via Livornese 1291, San Piero a Grado, Pisa (Italy)

2016-11-15

Highlights: • FFTBM-SM is an improved Fast Fourier Transform Base Method by signal mirroring. • FFTBM-SM has been applied to accuracy assessment of MELCOR code predictions. • The case studied was Station Black-Out accident in PSB-VVER integral test facility. • FFTBM-SM eliminates fluctuations of accuracy indices when signals sharply change. • Accuracy assessment is performed in a more realistic and consistent way by FFTBM-SM. - Abstract: This paper deals with the application of Fast Fourier Transform Base Method (FFTBM) with signal mirroring (FFTBM-SM) to assess accuracy of MELCOR code. This provides deeper insights into how the accuracy of MELCOR code in predictions of thermal-hydraulic parameters varies during transients. The case studied was modeling of Station Black-Out (SBO) accident in PSB-VVER integral test facility by MELCOR code. The accuracy of this thermal-hydraulic modeling was previously quantified using original FFTBM in a few number of time-intervals, based on phenomenological windows of SBO accident. Accuracy indices calculated by original FFTBM in a series of time-intervals unreasonably fluctuate when the investigated signals sharply increase or decrease. In the current study, accuracy of MELCOR code is quantified using FFTBM-SM in a series of increasing time-intervals, and the results are compared to those with original FFTBM. Also, differences between the accuracy indices of original FFTBM and FFTBM-SM are investigated and correction factors calculated to eliminate unphysical effects in original FFTBM. The main findings are: (1) replacing limited number of phenomena-based time-intervals by a series of increasing time-intervals provides deeper insights about accuracy variation of the MELCOR calculations, and (2) application of FFTBM-SM for accuracy evaluation of the MELCOR predictions, provides more reliable results than original FFTBM by eliminating the fluctuations of accuracy indices when experimental signals sharply increase or

Advances in analysis of pre-earthquake thermal anomalies by analyzing IR satellite data

Science.gov (United States)

Ouzounov, D.; Bryant, N.; Filizzola, C.; Pergola, N.; Taylor, P.; Tramutoli, V.

Presented work addresses the possible relationship between tectonic stress, electro-chemical and thermodynamic processes in the atmosphere and increasing infrared (IR) flux as part of a larger family of electromagnetic (EM) phenomena related to earthquake activity. Thermal infra-red (TIR) surveys performed by polar orbiting (NOAA/AVHRR, MODIS) and geosynchronous weather satellites (GOES, METEOSAT) seems to indicate the appearance (from days to weeks before the event) of "anomalous" space-time TIR transients associated with the place (epicentral area, linear structures and fault systems) and the time of occurrence of a number of major earthquakes with M>5 and focal depths no deeper than 50km. As Earth emitted in 8-14 microns range the TIR signal measured from satellite strongly vary depending on meteorological conditions and other factors (space-time changes in atmospheric transmittance, time/season, solar and satellite zenithal angles and etc) independent from seismic activity, a preliminary definition of "anomalous TIR signal" should be given. To provide reliable discrimination of thermal anomalous area from the natural events (seasonal changes, local morphology) new robust approach (RAT) has been recently proposed (and successfully applied in the field of the monitoring of the major environmental risks) that permits to give a statistically based definition of thermal info-red (TIR) anomaly and reduce of false events detection. New techniques also were specifically developed to assure the precise co-registration of all satellite scenes and permit accurate time-series analysis of satellite observations. As final results we present examples of most recent 2000/2004 worldwide strong earthquakes and the techniques used to capture the tracks of thermal emission mid-IR anomalies and methodology for practical future use of such phenomena in the early warning systems.

Determination of the Thermal Offset of the Eppley Precision Spectral Pyranometer

Science.gov (United States)

Haeffelin, Martial; Kato, Seiji; Smith, Amie M.; Rutledge, C. Ken; Charlock, Thomas P.; Mahan, J. Robert

2001-01-01

Eppley's precision spectral pyranometer (PSP) is used in networks around the world to measure downwelling diffuse and global solar irradiance at the surface of the Earth. In recent years several studies have shown significant discrepancy between irradiances measured by pyranometers and those computed by atmospheric radiative transfer models. Pyranometer measurements have been questioned because observed diffuse irradiances sometimes are below theoretical minimum values for a pure molecular atmosphere, and at night the instruments often produce nonzero signals ranging between + 5 and - 10 W/sq m. We install thermistor sondes in the body of a PSP as well as on its inner dome to monitor the temperature gradients within the instrument, and we operate a pyrgeometer (PIR) instrument side by side with the PSP. We derive a relationship between the PSP output and thermal radiative exchange by the dome and the detector and a relationship between the PSP output and the PIR thermopile output (net-IR). We determine the true PSP offset by quickly capping the instrument at set time intervals. For a ventilated and shaded PSP, the thermal offset can reach - 15 W/sq m under clear skies, whereas it remains close to zero for low overcast clouds. We estimate the PSP thermal offset by two methods: (1) using the PSP temperatures and (2) using the PIR net-IR signal. The offset computed from the PSP temperatures yields a reliable estimate of the true offset (+/- 1 W/sq m). The offset computed from net-IR is consistent with the true offset at night and under overcast skies but predicts only part of the true range under clear skies.

Cyclic AMP-dependent signaling system is a primary metabolic target for non-thermal effect of microwaves on heart muscle hydration.

Science.gov (United States)

Narinyan, Lilia; Ayrapetyan, Sinerik

2017-01-01

Previously, we have suggested that cell hydration is a universal and extra-sensitive sensor for the structural changes of cell aqua medium caused by the impact of weak chemical and physical factors. The aim of present work is to elucidate the nature of the metabolic messenger through which physiological solution (PS) treated by non-thermal (NT) microwaves (MW) could modulate heart muscle hydration of rats. For this purpose, the effects of NT MW-treated PS on heart muscle hydration, [ 3 H]-ouabain binding with cell membrane, 45 Ca 2+ uptake and intracellular cyclic nucleotides contents in vivo and in vitro experiments were studied. It is shown that intraperitoneal injections of both Sham-treated PS and NT MW-treated PS elevate heart muscle hydration. However, the effect of NT MW-treated PS on muscle hydration is more pronounced than the effect of Sham-treated PS. In vitro experiments NT MW-treated PS has dehydration effect on muscle, which is not changed by decreasing Na + gradients on membrane. Intraperitoneal injection of Sham- and NT MW-treated PS containing 45 Ca 2+ have similar dehydration effect on muscle, while NT MW-treated PS has activation effect on Na + /Ca 2+ exchange in reverse mode. The intraperitoneal injection of NT MW-treated PS depresses [ 3 H]-ouabain binding with its high-affinity membrane receptors, elevates intracellular cAMP and decreases cGMP contents. Based on the obtained data, it is suggested that cAMP-dependent signaling system serves as a primary metabolic target for NT MW effect on heart muscle hydration.

Thermal-grating contributions to degenerate four-wave mixing in nitric oxide

International Nuclear Information System (INIS)

Danehy, P.M.; Paul, P.H.; Farrow, R.L.

1995-01-01

We report investigations of degenerate four-wave mixing (DFWM) line intensities in the A 2 Σ + left-arrow X 2 Π electronic transitions of nitric oxide. Contributions from population gratings (spatially varying perturbations in the level populations of absorbing species) and thermal gratings (spatially varying perturbations in the overall density) were distinguished and compared by several experimental and analytical techniques. For small quantities of nitric oxide in a strongly quenching buffer gas (carbon dioxide), we found that thermal-grating contributions dominated at room temperature for gas pressures of ∼0.5 atm and higher. In a nearly nonquenching buffer (nitrogen) the population-grating mechanism dominated at pressures of ∼1.0 atm and lower. At higher temperatures in an atmospheric-pressure methane/air flame, population gratings of nitric oxide also dominated. We propose a simple model for the ratio of thermal- to population-grating scattering intensities that varies as P 4 T -4.4 . Preliminary investigations of the temperature dependence and detailed studies of the pressure dependence are in agreement with this model. Measurements of the temporal evolution and the peak intensity of isolated thermal-grating signals are in detailed agreement with calculations based on a linearized hydrodynamic model [J. Opt. Soc. Am. B 12, 384 (1995)]. copyright 1995 Optical Society of America

Investigation of defects in In–Ga–Zn oxide thin film using electron spin resonance signals

International Nuclear Information System (INIS)

Nonaka, Yusuke; Kurosawa, Yoichi; Komatsu, Yoshihiro; Ishihara, Noritaka; Oota, Masashi; Nakashima, Motoki; Hirohashi, Takuya; Takahashi, Masahiro; Yamazaki, Shunpei; Obonai, Toshimitsu; Hosaka, Yasuharu; Koezuka, Junichi; Yamauchi, Jun

2014-01-01

In–Ga–Zn oxide (IGZO) is a next-generation semiconductor material seen as an alternative to silicon. Despite the importance of the controllability of characteristics and the reliability of devices, defects in IGZO have not been fully understood. We investigated defects in IGZO thin films using electron spin resonance (ESR) spectroscopy. In as-sputtered IGZO thin films, we observed an ESR signal which had a g-value of g = 2.010, and the signal was found to disappear under thermal treatment. Annealing in a reductive atmosphere, such as N 2 atmosphere, generated an ESR signal with g = 1.932 in IGZO thin films. The temperature dependence of the latter signal suggests that the signal is induced by delocalized unpaired electrons (i.e., conduction electrons). In fact, a comparison between the conductivity and ESR signal intensity revealed that the signal's intensity is related to the number of conduction electrons in the IGZO thin film. The signal's intensity did not increase with oxygen vacancy alone but also with increases in both oxygen vacancy and hydrogen concentration. In addition, first-principle calculation suggests that the conduction electrons in IGZO may be generated by defects that occur when hydrogen atoms are inserted into oxygen vacancies

Investigation of defects in In–Ga–Zn oxide thin film using electron spin resonance signals

Energy Technology Data Exchange (ETDEWEB)

Nonaka, Yusuke; Kurosawa, Yoichi; Komatsu, Yoshihiro; Ishihara, Noritaka; Oota, Masashi; Nakashima, Motoki; Hirohashi, Takuya; Takahashi, Masahiro; Yamazaki, Shunpei [Semiconductor Energy Laboratory Co., Ltd., 398 Hase, Atsugi, Kanagawa 243-0036 (Japan); Obonai, Toshimitsu; Hosaka, Yasuharu; Koezuka, Junichi [Advanced Film Device, Inc., 161-2 Masuzuka, Tsuga-machi, Tochigi, Tochigi 328-0114 (Japan); Yamauchi, Jun [Semiconductor Energy Laboratory Co., Ltd., 398 Hase, Atsugi, Kanagawa 243-0036 (Japan); Emeritus Professor of Kyoto University, Oiwake-cho, Kitashirakawa, Kyoto 606-8502 (Japan)

2014-04-28

In–Ga–Zn oxide (IGZO) is a next-generation semiconductor material seen as an alternative to silicon. Despite the importance of the controllability of characteristics and the reliability of devices, defects in IGZO have not been fully understood. We investigated defects in IGZO thin films using electron spin resonance (ESR) spectroscopy. In as-sputtered IGZO thin films, we observed an ESR signal which had a g-value of g = 2.010, and the signal was found to disappear under thermal treatment. Annealing in a reductive atmosphere, such as N{sub 2} atmosphere, generated an ESR signal with g = 1.932 in IGZO thin films. The temperature dependence of the latter signal suggests that the signal is induced by delocalized unpaired electrons (i.e., conduction electrons). In fact, a comparison between the conductivity and ESR signal intensity revealed that the signal's intensity is related to the number of conduction electrons in the IGZO thin film. The signal's intensity did not increase with oxygen vacancy alone but also with increases in both oxygen vacancy and hydrogen concentration. In addition, first-principle calculation suggests that the conduction electrons in IGZO may be generated by defects that occur when hydrogen atoms are inserted into oxygen vacancies.

Decay of organic free radicals in γ-ray irradiated pepper during thermal treatment as detected by electron spin resonance spectroscopy

International Nuclear Information System (INIS)

Ukai, Mitsuko; Shimoyama, Yuhei

2004-01-01

Using electron spin resonance (ESR) spectroscopy we analysed the thermal decay process of radicals in γ-Irradiated pepper Upon irradiation, the satellite signals were newly induced and appeared at the symmetric positions of the organic free radical, i.e., the g=2.0 signal. Heat treatment decreased the satellite signals exponentially. The ESR signal of the pepper heated for more than 10 min was essentially the same as that before irradiation. To evaluate the radical decay by heat-treatment, we formulated a time-dependent master equation. We could evaluate the time constant of the radical decay based upon the general solution of the equation together with the nonlinear least-squares method

On the effect of optical and isothermal treatments on luminescence signals from feldspars

International Nuclear Information System (INIS)

Pagonis, Vasilis; Polymeris, George; Kitis, George

2015-01-01

During luminescence dosimetry and luminescence dating applications it is often necessary to precondition the geological samples by applying a thermal or optical treatment before measuring the luminescence signal. In luminescence applications using apatites or feldspars, measurement of continuous-wave infrared or optically stimulated signals (CW-IRSL and CW-OSL) are customarily preceded by either an isothermal heating of the samples at a fixed temperature for a short time interval, or alternatively by optically bleaching the samples using light from LEDs with the appropriate wavelength. This paper presents new analytical equations which can be used to describe these commonly employed double experimental procedures. The equations are based on a recently published model which assumes that tunneling processes are taking place in random distributions of donor–acceptor pairs. The concentration of charge carriers during the CW-IRSL or CW-OSL experiment is expressed in terms of the parameters of the preceding thermal or optical bleaching procedure, and depends also on the distribution of distances between electron and hole pairs. The analytical equations in this paper are compared with experimental data from a feldspar sample which undergoes an isothermal procedure followed by measurement of the CW-IRSL signal. Additional comparisons with experiment are provided using a feldspar sample which undergoes an infrared bleaching process, followed by measurement of the CW-OSL signal. These results and conditions under which the equations can be used are discussed within the framework of the model. - Highlights: • CW-IRSL and CW-OSL measurements are preceded by heating or optical bleaching. • New analytical equations are derived to describe these double experimental procedures. • Equations are compared with data from a feldspar sample following isothermal procedure. • Equations are compared with data from a feldspar sample following optical bleaching.

Non-Fourier based thermal-mechanical tissue damage prediction for thermal ablation.

Science.gov (United States)

Li, Xin; Zhong, Yongmin; Smith, Julian; Gu, Chengfan

2017-01-02

Prediction of tissue damage under thermal loads plays important role for thermal ablation planning. A new methodology is presented in this paper by combing non-Fourier bio-heat transfer, constitutive elastic mechanics as well as non-rigid motion of dynamics to predict and analyze thermal distribution, thermal-induced mechanical deformation and thermal-mechanical damage of soft tissues under thermal loads. Simulations and comparison analysis demonstrate that the proposed methodology based on the non-Fourier bio-heat transfer can account for the thermal-induced mechanical behaviors of soft tissues and predict tissue thermal damage more accurately than classical Fourier bio-heat transfer based model.

Methods of forming thermal management systems and thermal management methods

Science.gov (United States)

Gering, Kevin L.; Haefner, Daryl R.

2012-06-05

A thermal management system for a vehicle includes a heat exchanger having a thermal energy storage material provided therein, a first coolant loop thermally coupled to an electrochemical storage device located within the first coolant loop and to the heat exchanger, and a second coolant loop thermally coupled to the heat exchanger. The first and second coolant loops are configured to carry distinct thermal energy transfer media. The thermal management system also includes an interface configured to facilitate transfer of heat generated by an internal combustion engine to the heat exchanger via the second coolant loop in order to selectively deliver the heat to the electrochemical storage device. Thermal management methods are also provided.

Automation of a thermal ionisation mass spectrometer

International Nuclear Information System (INIS)

Pamula, A.; Leuca, M.; Albert, S.; Benta, Adriana

2001-01-01

A thermal ionization mass spectrometer was upgraded in order to be monitored by a PC. A PC-LMP-16 National Instruments data acquisition board was used for the ion current channel and the Hall signal channel. A dedicated interface was built to allow commands from the computer to the current supply of the analyzing magnet and to the high voltage unit of the mass spectrometer. A software application was worked out to perform the adjustment of the spectrometer, magnetic scanning and mass spectra acquisition, data processing and isotope ratio determination. The apparatus is used for isotope ratio 235 U/ 238 U determination near the natural abundance. A peak jumping technique is applied to choose between the 235 U and 238 U signal, by switching the high voltage applied to the ion source between two preset values. This avoids the delay between the acquisition of the peaks of interest, a delay that would appear in the case of a 'pure' magnetic scanning. Corrections are applied for the mass discrimination effects and a statistical treatment of the data is achieved. (authors)

Thermal Wigner Operator in Coherent Thermal State Representation and Its Application

Institute of Scientific and Technical Information of China (English)

FAN HongYi

2002-01-01

In the coherent thermal state representation we introduce thermal Wigner operator and find that it is"squeezed" under the thermal transformation. The thermal Wigner operator provides us with a new direct and neatapproach for deriving Wigner functions of thermal states.

A thermal engine for underwater glider driven by ocean thermal energy

International Nuclear Information System (INIS)

Yang, Yanan; Wang, Yanhui; Ma, Zhesong; Wang, Shuxin

2016-01-01

Highlights: • Thermal engine with a double-tube structure is developed for underwater glider. • Isostatic pressing technology is effective to increase volumetric change rate. • Actual volumetric change rate reaches 89.2% of the theoretical value. • Long term sailing of 677 km and 27 days is achieved by thermal underwater glider. - Graphical Abstract: - Abstract: Underwater glider is one of the most popular platforms for long term ocean observation. Underwater glider driven by ocean thermal energy extends the duration and range of underwater glider powered by battery. Thermal engine is the core device of underwater glider to harvest ocean thermal energy. In this paper, (1) model of thermal engine was raised by thermodynamics method and the performance of thermal engine was investigated, (2) thermal engine with a double-tube structure was developed and isostatic pressing technology was applied to improve the performance for buoyancy driven, referencing powder pressing theory, (3) wall thickness of thermal engine was optimized to reduce the overall weight of thermal engine, (4) material selection and dimension determination were discussed for a faster heat transfer design, by thermal resistance analysis, (5) laboratory test and long term sea trail were carried out to test the performance of thermal engine. The study shows that volumetric change rate is the most important indicator to evaluating buoyancy-driven performance of a thermal engine, isostatic pressing technology is effective to improve volumetric change rate, actual volumetric change rate can reach 89.2% of the theoretical value and the average power is about 124 W in a typical diving profile. Thermal engine developed by Tianjin University is a superior thermal energy conversion device for underwater glider. Additionally, application of thermal engine provides a new solution for miniaturization of ocean thermal energy conversion.

Chlorine as a geobarometer tool: Application to the explosive eruptions of the Volcanic Campanian District (Mount Somma-Vesuvius, Phlegrean Fields, Ischia)

Science.gov (United States)

Balcone-Boissard, Hélène; Boudon, Georges; Zdanowicz, Géraldine; Orsi, Giovanni; Civetta, Lucia; Webster, Jim D.; Cioni, Raffaello; D'Antonio, Massimo

2016-04-01

One of the current stakes in modern volcanology is the definition of magma storage conditions which has direct implications on the eruptive style and thus on the associated risks and the management of likely related crisis. In alkaline differentiated magmas, chlorine (Cl), contrary to H2O, occurs as a minor volatile species but may be used as a geobarometer. Numerous experimental studies on Cl solubility have highlighted its saturation conditions in silicate melts. The NaCl-H2O system is characterized by immiscibility under wide ranges of pressure, temperature and NaCl content (pre-eruptive conditions, of utmost importance for the interpretation of the monitoring data and the identification of precursory signals.

Thermal Wigner Operator in Coherent Thermal State Representation and Its Application

Institute of Scientific and Technical Information of China (English)

FANHong－Yi

2002-01-01

In the coherent thermal state representation we introduce thermal Wigner operator and find that it is “squeezed” under the thermal transformation.The thermal Wigner operator provides us with a new direct and neat approach for deriving Wigner functions of thermal states.

Thermal modelling using discrete vasculature for thermal therapy: a review

Science.gov (United States)

Kok, H.P.; Gellermann, J.; van den Berg, C.A.T.; Stauffer, P.R.; Hand, J.W.; Crezee, J.

2013-01-01

Reliable temperature information during clinical hyperthermia and thermal ablation is essential for adequate treatment control, but conventional temperature measurements do not provide 3D temperature information. Treatment planning is a very useful tool to improve treatment quality and substantial progress has been made over the last decade. Thermal modelling is a very important and challenging aspect of hyperthermia treatment planning. Various thermal models have been developed for this purpose, with varying complexity. Since blood perfusion is such an important factor in thermal redistribution of energy in in vivo tissue, thermal simulations are most accurately performed by modelling discrete vasculature. This review describes the progress in thermal modelling with discrete vasculature for the purpose of hyperthermia treatment planning and thermal ablation. There has been significant progress in thermal modelling with discrete vasculature. Recent developments have made real-time simulations possible, which can provide feedback during treatment for improved therapy. Future clinical application of thermal modelling with discrete vasculature in hyperthermia treatment planning is expected to further improve treatment quality. PMID:23738700

A Real-Time Thermal Self-Elimination Method for Static Mode Operated Freestanding Piezoresistive Microcantilever-Based Biosensors.

Science.gov (United States)

Ku, Yu-Fu; Huang, Long-Sun; Yen, Yi-Kuang

2018-02-28

Here, we provide a method and apparatus for real-time compensation of the thermal effect of single free-standing piezoresistive microcantilever-based biosensors. The sensor chip contained an on-chip fixed piezoresistor that served as a temperature sensor, and a multilayer microcantilever with an embedded piezoresistor served as a biomolecular sensor. This method employed the calibrated relationship between the resistance and the temperature of piezoresistors to eliminate the thermal effect on the sensor, including the temperature coefficient of resistance (TCR) and bimorph effect. From experimental results, the method was verified to reduce the signal of thermal effect from 25.6 μV/°C to 0.3 μV/°C, which was approximately two orders of magnitude less than that before the processing of the thermal elimination method. Furthermore, the proposed approach and system successfully demonstrated its effective real-time thermal self-elimination on biomolecular detection without any thermostat device to control the environmental temperature. This method realizes the miniaturization of an overall measurement system of the sensor, which can be used to develop portable medical devices and microarray analysis platforms.

Variable reflectivity signal mirrors and signal response measurements

International Nuclear Information System (INIS)

Vine, Glenn de; Shaddock, Daniel A; McClelland, David E

2002-01-01

Future gravitational wave detectors will include some form of signal mirror in order to alter the signal response of the device. We introduce interferometer configurations which utilize a variable reflectivity signal mirror allowing a tunable peak frequency and variable signal bandwidth. A detector configured with a Fabry-Perot cavity as the signal mirror is compared theoretically with one using a Michelson interferometer for a signal mirror. A system for the measurement of the interferometer signal responses is introduced. This technique is applied to a power-recycled Michelson interferometer with resonant sideband extraction. We present broadband measurements of the benchtop prototype's signal response for a range of signal cavity detunings. This technique is also applicable to most other gravitational wave detector configurations

Variable reflectivity signal mirrors and signal response measurements

CERN Document Server

Vine, G D; McClelland, D E

2002-01-01

Future gravitational wave detectors will include some form of signal mirror in order to alter the signal response of the device. We introduce interferometer configurations which utilize a variable reflectivity signal mirror allowing a tunable peak frequency and variable signal bandwidth. A detector configured with a Fabry-Perot cavity as the signal mirror is compared theoretically with one using a Michelson interferometer for a signal mirror. A system for the measurement of the interferometer signal responses is introduced. This technique is applied to a power-recycled Michelson interferometer with resonant sideband extraction. We present broadband measurements of the benchtop prototype's signal response for a range of signal cavity detunings. This technique is also applicable to most other gravitational wave detector configurations.

Determination of the ion thermal diffusivity from neutron emission profiles in decay

Energy Technology Data Exchange (ETDEWEB)

Sasao, M. (National Inst. for Fusion Science, Nagoya (Japan)); Adams, J.M. (AEA Industrial Technology, Harwell (United Kingdom)); Conroy, S.; Jarvis, O.N.; Marcus, F.B.; Sadler, G.; Belle, P. van (Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking)

1994-01-01

Spatial profiles of the neutron emission from deuterium plasmas are routinely obtained at the Joint European Torus (JET) using the line-integrated signals measured with a multichannel instrument. It is shown that the manner in which these profiles relax following the termination of strong heating with neutral beam injection (NBI) permits the local thermal diffusivity ([chi][sub i]) to be obtained with an accuracy of about 20%. (author).

Estimating Transmitted-Signal Phase Variations for Uplink Array Antennas

Science.gov (United States)

Paal, Leslie; Mukai, Ryan; Vilntrotter, Victor; Cornish, Timothy; Lee, Dennis

2009-01-01

A method of estimating phase drifts of microwave signals distributed to, and transmitted by, antennas in an array involves the use of the signals themselves as phase references. The method was conceived as part of the solution of the problem of maintaining precise phase calibration required for proper operation of an array of Deep Space Network (DSN) antennas on Earth used for communicating with distant spacecraft at frequencies between 7 and 8 GHz. The method could also be applied to purely terrestrial phased-array radar and other radio antenna array systems. In the DSN application, the electrical lengths (effective signal-propagation path lengths) of the various branches of the system for distributing the transmitted signals to the antennas are not precisely known, and they vary with time. The variations are attributable mostly to thermal expansion and contraction of fiber-optic and electrical signal cables and to a variety of causes associated with aging of signal-handling components. The variations are large enough to introduce large phase drifts at the signal frequency. It is necessary to measure and correct for these phase drifts in order to maintain phase calibration of the antennas. A prior method of measuring phase drifts involves the use of reference-frequency signals separate from the transmitted signals. A major impediment to accurate measurement of phase drifts over time by the prior method is the fact that although DSN reference-frequency sources separate from the transmitting signal sources are stable and accurate enough for most DSN purposes, they are not stable enough for use in maintaining phase calibrations, as required, to within a few degrees over times as long as days or possibly even weeks. By eliminating reliance on the reference-frequency subsystem, the present method overcomes this impediment. In a DSN array to which the present method applies (see figure), the microwave signals to be transmitted are generated by exciters in a signal

Thermal efficiency on welding of AA6061-T6 alloy by modified indirect electric arc and current signals digitalisation

International Nuclear Information System (INIS)

Ambriz, R. R.; Barrera, G.; Garcia, R.; Lopez, V. H.

2009-01-01

The results of the thermal efficiency on welding by modified indirect electric arc technique (MIEA) [1] of the 6061- T6 aluminum alloy are presented. These values are in a range of 90 to 94 %, which depend of the preheating employed. Thermal efficiency was obtained by means of a balance energy which considers the heat input, the amount of melted mass of the welding profiles, and welding parameters during the joining, especially of the arc current data acquisition. Also, some dimensionless parameters were employed in order to determine the approximation grade of the melted pool, the heat affected zone (HAZ), and their corresponding values with the experimental results. (Author) 13 refs

Study on the Cross Plane Thermal Transport of Polycrystalline Molybdenum Nanofilms by Applying Picosecond Laser Transient Thermoreflectance Method

Directory of Open Access Journals (Sweden)

Tingting Miao

2014-01-01

Full Text Available Thin metal films are widely used as interconnecting wires and coatings in electronic devices and optical components. Reliable thermophysical properties of the films are required from the viewpoint of thermal management. The cross plane thermal transport of four polycrystalline molybdenum nanofilms with different thickness deposited on glass substrates has been studied by applying the picosecond laser transient thermoreflectance technique. The measurement is performed by applying both front pump-front probe and rear pump-front probe configurations with high quality signal. The determined cross plane thermal diffusivity of the Mo films greatly decreases compared to the corresponding bulk value and tends to increase as films become thicker, exhibiting significant size effect. The main mechanism responsible for the thermal diffusivity decrease of the present polycrystalline Mo nanofilms is the grain boundary scattering on the free electrons. Comparing the cross plane thermal diffusivity and inplane electrical conductivity indicates the anisotropy of the transport properties of the Mo films.

Thermal conductivity characteristics of dewatered sewage sludge by thermal hydrolysis reaction.

Science.gov (United States)

Song, Hyoung Woon; Park, Keum Joo; Han, Seong Kuk; Jung, Hee Suk

2014-12-01

The purpose of this study is to quantify the thermal conductivity of sewage sludge related to reaction temperature for the optimal design of a thermal hydrolysis reactor. We continuously quantified the thermal conductivity of dewatered sludge related to the reaction temperature. As the reaction temperature increased, the dewatered sludge is thermally liquefied under high temperature and pressure by the thermal hydrolysis reaction. Therefore, the bound water in the sludge cells comes out as free water, which changes the dewatered sludge from a solid phase to slurry in a liquid phase. As a result, the thermal conductivity of the sludge was more than 2.64 times lower than that of the water at 20. However, above 200, it became 0.704 W/m* degrees C, which is about 4% higher than that of water. As a result, the change in physical properties due to thermal hydrolysis appears to be an important factor for heat transfer efficiency. Implications: The thermal conductivity of dewatered sludge is an important factor the optimal design of a thermal hydrolysis reactor. The dewatered sludge is thermally liquefied under high temperature and pressure by the thermal hydrolysis reaction. The liquid phase slurry has a higher thermal conductivity than pure water.

Fish diversity in adjacent ambient, thermal, and post-thermal freshwater streams

International Nuclear Information System (INIS)

McFarlane, R.W.

1976-01-01

The Savannah River Plant area is drained by five streams of various sizes and thermal histories. One has never been thermally stressed, two presently receive thermal effluent, and two formerly received thermal effluent from nuclear production reactors. Sixty-four species of fishes are known to inhabit these streams; 55 species is the highest number obtained from any one stream. Thermal effluent in small streams excludes fish during periods of high temperatures, but the streams are rapidly reinvaded when temperatures subside below lethal limits. Some cyprinids become extinct in nonthermal tributaries upstream from the thermal effluents after extended periods of thermal stress. This extinction is similar to that which follows stream impoundment. Post-thermal streams rapidly recover their fish diversity and abundance. The alteration of the streambed and removal of overhead canopy may change the stream characteristics and modify the post-thermal fish fauna

A novel detector assembly for detecting thermal neutrons, fast neutrons and gamma rays

Energy Technology Data Exchange (ETDEWEB)

Cester, D., E-mail: davide.cester@gmail.com [Dipartimento di Fisica ed Astronomia dell' Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); Lunardon, M.; Moretto, S. [Dipartimento di Fisica ed Astronomia dell' Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); INFN Sezione di Padova, Via Marzolo 8, I-35131 Padova (Italy); Nebbia, G. [INFN Sezione di Padova, Via Marzolo 8, I-35131 Padova (Italy); Pino, F. [Dipartimento di Fisica ed Astronomia dell' Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); Sajo-Bohus, L. [Dipartimento di Fisica ed Astronomia dell' Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); Laboratorio de Fisica Nuclear, Universidad Simon Bolivar, Apartado 89000, 1080 A Caracas (Venezuela, Bolivarian Republic of); Stevanato, L.; Bonesso, I.; Turato, F. [Dipartimento di Fisica ed Astronomia dell' Università di Padova, Via Marzolo 8, I-35131 Padova (Italy)

2016-09-11

A new composite detector has been developed by combining two different commercial scintillators. The device has the capability to detect gamma rays as well as thermal and fast neutrons; the signal discrimination between the three types is performed on-line by means of waveform digitizers and PSD algorithms. This work describes the assembled detector and its discrimination performance to be employed in the applied field.

A novel detector assembly for detecting thermal neutrons, fast neutrons and gamma rays

International Nuclear Information System (INIS)

Cester, D.; Lunardon, M.; Moretto, S.; Nebbia, G.; Pino, F.; Sajo-Bohus, L.; Stevanato, L.; Bonesso, I.; Turato, F.

2016-01-01

A new composite detector has been developed by combining two different commercial scintillators. The device has the capability to detect gamma rays as well as thermal and fast neutrons; the signal discrimination between the three types is performed on-line by means of waveform digitizers and PSD algorithms. This work describes the assembled detector and its discrimination performance to be employed in the applied field.

The development of on-line thermal performance monitors in Nuclear Electric Company's stations

International Nuclear Information System (INIS)

Conner, A.S.

1992-01-01

The paper examines the economic benefits of using on-line monitoring techniques in assisting Station Staff with the task of optimising the efficient use of reactor fuel. The role of thermal performance monitoring for detecting changes in plant condition is also examined and the way in which the data can be used by engineers to assist with the preparation of operating and maintenance programmes. To enable genuine gradual changes in plant performance to be detected when operating against a background of changing plant signal accuracy conditions, plant transducers have to be calibrated on a regular basis. This can be both costly and labour intensive. To reduce this requirement for regular calibrations, an automatic software signal verification program has been developed for use in on-line monitoring schemes. It forms part of the total unit performance calculation package and uses a whole plant model to verify plant signals. All plant signals used to calculate unit heat rate are verified typically every 15 minutes with signals going outside predetermined limits being automatically reported to the user. The program is interactive allowing the user to interrogate the condition of the signal, with respect to both its error magnitude and rate of drift outside signal limits. The program runs in real time mode on a Workstation connected directly to the plant

Natural selection on thermal preference, critical thermal maxima and locomotor performance.

Science.gov (United States)

Gilbert, Anthony L; Miles, Donald B

2017-08-16

Climate change is resulting in a radical transformation of the thermal quality of habitats across the globe. Whereas species have altered their distributions to cope with changing environments, the evidence for adaptation in response to rising temperatures is limited. However, to determine the potential of adaptation in response to thermal variation, we need estimates of the magnitude and direction of natural selection on traits that are assumed to increase persistence in warmer environments. Most inferences regarding physiological adaptation are based on interspecific analyses, and those of selection on thermal traits are scarce. Here, we estimate natural selection on major thermal traits used to assess the vulnerability of ectothermic organisms to altered thermal niches. We detected significant directional selection favouring lizards with higher thermal preferences and faster sprint performance at their optimal temperature. Our analyses also revealed correlational selection between thermal preference and critical thermal maxima, where individuals that preferred warmer body temperatures with cooler critical thermal maxima were favoured by selection. Recent published estimates of heritability for thermal traits suggest that, in concert with the strong selective pressures we demonstrate here, evolutionary adaptation may promote long-term persistence of ectotherms in altered thermal environments. © 2017 The Author(s).

Studies on thermal properties and thermal control effectiveness of a new shape-stabilized phase change material with high thermal conductivity

International Nuclear Information System (INIS)

Cheng Wenlong; Liu Na; Wu Wanfan

2012-01-01

In order to overcome the difficulty of conventional phase change materials (PCMs) in packaging, the shape-stabilized PCMs are proposed to be used in the electronic device thermal control. However, the conventional shape-stabilized PCMs have the drawback of lower thermal conductivity, so a new shape-stabilized PCM with high thermal conductivity, which is suitable for thermal control of electronic devices, is prepared. The thermal properties of n-octadecane-based shape-stabilized PCM are tested and analyzed. The heat storage/release performance is studied by numerical simulation. Its thermal control effect for electronic devices is also discussed. The results show that the expanded graphite (EG) can greatly improve the thermal conductivity of the material with little effect on latent heat and phase change temperature. When the mass fraction of EG is 5%, thermal conductivity has reached 1.76 W/(m K), which is over 4 times than that of the original one. Moreover, the material has larger latent heat and good thermal stability. The simulation results show that the material can have good heat storage/release performance. The analysis of the effect of thermal parameters on thermal control effect for electronic devices provides references to the design of phase change thermal control unit. - Highlights: ► A new shape-stabilized PCM with higher thermal conductivity is prepared. ► The material overcomes the packaging difficulty of traditional PCMs used in thermal control unit. ► The EG greatly improves thermal conductivity with little effect on latent heat. ► The material has high thermal stability and good heat storage/release performance. ► The effectiveness of the material for electronic device thermal control is proved.

Feasibility of coupling a thermal/optical carbon analyzer to a quadrupole mass spectrometer for enhanced PM2.5 speciation.

Science.gov (United States)

Riggio, Gustavo M; Chow, Judith C; Cropper, Paul M; Wang, Xiaoliang; Yatavelli, Reddy L N; Yang, Xufei; Watson, John G

2018-05-01

A thermal/optical carbon analyzer (TOA), normally used for quantification of organic carbon (OC) and elemental carbon (EC) in PM 2.5 (fine particulate matter) speciation networks, was adapted to direct thermally evolved gases to an electron impact quadrupole mass spectrometer (QMS), creating a TOA-QMS. This approach produces spectra similar to those obtained by the Aerodyne aerosol mass spectrometer (AMS), but the ratios of the mass to charge (m/z) signals differ and must be remeasured using laboratory-generated standards. Linear relationships are found between TOA-QMS signals and ammonium (NH 4 + ), nitrate (NO 3 - ), and sulfate (SO 4 2- ) standards. For ambient samples, however, positive deviations are found for SO 4 2- , compensated by negative deviations for NO 3 - , at higher concentrations. This indicates the utility of mixed-compound standards for calibration or separate calibration curves for low and high ion concentrations. The sum of the QMS signals across all m/z after removal of the NH 4 + , NO 3 - , and SO 4 2- signals was highly correlated with the carbon content of oxalic acid (C₂H₂O₄) standards. For ambient samples, the OC derived from the TOA-QMS method was the same as the OC derived from the standard IMPROVE_A TOA method. This method has the potential to reduce complexity and costs for speciation networks, especially for highly polluted urban areas such as those in Asia and Africa. Ammonium, nitrate, and sulfate can be quantified by the same thermal evolution analysis applied to organic and elemental carbon. This holds the potential to replace multiple parallel filter samples and separate laboratory analyses with a single filter and a single analysis to account for a large portion of the PM 2.5 mass concentration.

Study of elastic and thermal parameters of a composite material fluoro-plastic - thermo-exfoliated graphite by photothermoacoustic method

International Nuclear Information System (INIS)

Kozachenko, V.V.; Kucherov, I.Ya.; Revo, S.L.

2004-01-01

Full text: The composite materials (CM) with success are widely used in a science and in an industry. From the practical point of view important for CM the mechanical and thermal properties are. Therefore, study of these properties for them is the important problem. At change of a temperature state of materials of their property in many cases are featured by combinations of elastic and thermal parameters E/1-σ=E n and χ/ρc=D T , where E, -σ, ρ and c are the Young's modulus, Poisson's ratio, thermal conductivity coefficient, density and specific heat of materials, respectively. Now for examination of substances in various aggregate states has received development a photothermoacoustic (PTA) method. As shown in this work, use a PTA method with piezoelectric detection of a PTA signal from a layered plate, under certain conditions, allows immediately determining the reduced Young's modulus E n and thermal diffusivity D T . Therefore, the purpose of this work was study the PTA effect with piezoelectric detection of an informative signal from CM. Were explored steel-copper CM such as 'sandwich' and fluoro plastic-thermo exfoliated graphite FP-TEG CM. Explored triplex structure as a plate made of a CM sample and a two-layer piezoelectric transducer. The surface of a CM is uniformly irradiated with a modulated light flux. The sample is heated and the thermal waves are generated. In the sample, the temperature field of thermal waves generates, due to the thermoelastic effect, acoustic vibration and waves that are registered by a piezoelectric. The rather low frequencies of modulation are considered, at which length of ultrasonic waves is much more than the reference sizes of structure (quasi-static approach). The amplitudes ratio and phase difference of voltages oscillations taken from separate layer of piezoelectric transducer, as functions of physical and geometrical parameters of structure and a frequency of a light flux modulation is found. Experimentally the

Thermal neutron flux distribution in ET-RR-2 reactor thermal column

Directory of Open Access Journals (Sweden)

Imam Mahmoud M.

2002-01-01

Full Text Available The thermal column in the ET-RR-2 reactor is intended to promote a thermal neutron field of high intensity and purity to be used for following tasks: (a to provide a thermal neutron flux in the neutron transmutation silicon doping, (b to provide a thermal flux in the neutron activation analysis position, and (c to provide a thermal neutron flux of high intensity to the head of one of the beam tubes leading to the room specified for boron thermal neutron capture therapy. It was, therefore, necessary to determine the thermal neutron flux at above mentioned positions. In the present work, the neutron flux in the ET-RR-2 reactor system was calculated by applying the three dimensional diffusion depletion code TRITON. According to these calculations, the reactor system is composed of the core, surrounding external irradiation grid, beryllium block, thermal column and the water reflector in the reactor tank next to the tank wall. As a result of these calculations, the thermal neutron fluxes within the thermal column and at irradiation positions within the thermal column were obtained. Apart from this, the burn up results for the start up core calculated according to the TRITION code were compared with those given by the reactor designer.

Heats of Mixing Using an Isothermal Titration Calorimeter: Associated Thermal Effects

Directory of Open Access Journals (Sweden)

Fabiola Socorro

2009-06-01

Full Text Available The correct determination of the energy generated or absorbed in the sample cell of an Isothermal Titration Calorimeter (ITC requires a thorough analysis of the calorimetric signal. This means the identification and quantification of any thermal effect inherent to the working method. In this work, it is carried out a review on several thermal effects, studied by us in previous work, and which appear when an ITC is used for measuring the heats of mixing of liquids in a continuous mode. These effects are due to: (i the difference between the temperature of the injected liquid and the temperature of the mixture during the mixing process, (ii the increase of the liquid volume located in the mixing cell and (iii the stirring velocity. Besides, methods for the identification and quantification of the mentioned effects are suggested.

Photovoltaic Thermal panels in collective thermal solar systems

International Nuclear Information System (INIS)

Elswijk, M.J.; Strootman, K.J.; Jong, M.J.M.; De Lange, E.T.N.; Smit, W.F.

2003-12-01

A feasibility study has been carried out to assess the options to apply photovoltaic/thermal panels (PVT-panels) in collective solar thermal systems in urban areas in the Netherlands. The study was focused on the technical (architecture and installations) and the economical feasibility of collective PVT-systems in comparison with conventional solar thermal systems and combinations of photovoltaic (PV) panels and solar collectors. The results of the study also give insight into cost and the market for PVT-panels. Three case studies in which collective solar collector systems were applied are analyzed again by simulating the installation of a PVT-panels system and a separate solar thermal PV system [nl

The development of monitoring techniques for thermal stratification in nuclear plant piping

International Nuclear Information System (INIS)

Sim, Cheul Muu; Joo, Young Sang; Yoon, Kwang Sik; Park, Chi Seung; Choi, Ha Lim; Moon, Jae Wha; Bae, Sang Ho.

1996-12-01

The conventional nondestructive testing has been performed in those area which are susceptible to thermal stress in according to NRC 88-08,11. In addition to that, it is necessary to set up a monitoring system to prevent severe thermal stress to pipes in early stages and to develop the non-intrusive techniques to diagnose the check valve because the thermal stratification has been caused by the malfunction of the check valve in ECCS pipe. Thermal stratification monitoring system has been designed and installed at ECCS line permanently and surge line temporally in YG nuclear power plant. The data is acceptable in according to TASCS guide line. Also, the data originated from ISMS is useful for the arrangement of a special UT program and stress analysis. Applying a togetherness of acoustics and magnetics signal, it is possible to determine the parameters of the function of the check valve internals without disassembling it. This series of tests show that the accelerometers can be use d to measure and to differentiate the three types of impacts; metal to metal impacts mechanical rubs, and worn internal parts. The magnet sensors can be used to detect the opening/closing of stainless check and fluttering of disk. (author). 50 refs., 5 tabs., 28 figs

The development of monitoring techniques for thermal stratification in nuclear plant piping

Energy Technology Data Exchange (ETDEWEB)

Sim, Cheul Muu; Joo, Young Sang; Yoon, Kwang Sik; Park, Chi Seung; Choi, Ha Lim; Moon, Jae Wha; Bae, Sang Ho

1996-12-01

The conventional nondestructive testing has been performed in those area which are susceptible to thermal stress in according to NRC 88-08,11. In addition to that, it is necessary to set up a monitoring system to prevent severe thermal stress to pipes in early stages and to develop the non-intrusive techniques to diagnose the check valve because the thermal stratification has been caused by the malfunction of the check valve in ECCS pipe. Thermal stratification monitoring system has been designed and installed at ECCS line permanently and surge line temporally in YG nuclear power plant. The data is acceptable in according to TASCS guide line. Also, the data originated from ISMS is useful for the arrangement of a special UT program and stress analysis. Applying a togetherness of acoustics and magnetics signal, it is possible to determine the parameters of the function of the check valve internals without disassembling it. This series of tests show that the accelerometers can be use d to measure and to differentiate the three types of impacts; metal to metal impacts mechanical rubs, and worn internal parts. The magnet sensors can be used to detect the opening/closing of stainless check and fluttering of disk. (author). 50 refs., 5 tabs., 28 figs.

Analysis of Thermo-Acoustic Emission from Damage in Composite Laminates under Thermal Cyclic Loading

International Nuclear Information System (INIS)

Kim, Young Bok; Min, Dae Hong; Lee, Deok Bo; Choi, Nak Sam

2001-01-01

An investigation on nondestructive evaluation of thermal stress-reduced damage in the composite laminates (3mm in thickness and [+45 6 /-45 6 ] S lay-up angles) has been performed using the thermo-acoustic emission technique. Reduction of thermo-AE events due to repetitive thermal load cycles showed a Kaiser effect. An analysis of the thermo-AE behavior determined the stress free temperature of composite laminates. Fiber fracture and matrix cracks were observed using the optical microscopy, scanning electron microscopy and ultrasonic C-sean. Short-Time Fourier Transform of thermo-AE signals offered the time-frequency characteristics which might classify the thermo-AE as three different types to estimate the damage processes of the composites

Current challenges for pre-earthquake electromagnetic emissions: shedding light from micro-scale plastic flow, granular packings, phase transitions and self-affinity notion of fracture process

Science.gov (United States)

Eftaxias, K.; Potirakis, S. M.

2013-10-01

Are there credible electromagnetic (EM) potential earthquake (EQ) precursors? This a question debated in the scientific community and there may be legitimate reasons for the critical views. The negative view concerning the existence of EM potential precursors is enhanced by features that accompany their observation which are considered as paradox ones, namely, these signals: (i) are not observed at the time of EQs occurrence and during the aftershock period, (ii) are not accompanied by large precursory strain changes, (iii) are not accompanied by simultaneous geodetic or seismological precursors and (iv) their traceability is considered problematic. In this work, the detected candidate EM potential precursors are studied through a shift in thinking towards the basic science findings relative to granular packings, micron-scale plastic flow, interface depinning, fracture size effects, concepts drawn from phase transitions, self-affine notion of fracture and faulting process, universal features of fracture surfaces, recent high quality laboratory studies, theoretical models and numerical simulations. We try to contribute to the establishment of strict criteria for the definition of an emerged EM anomaly as a possibly EQ-related one, and to the explanation of potential precursory EM features which have been considered as paradoxes. A three-stage model for EQ generation by means of pre-EQ fracture-induced EM emissions is proposed. The claim that the observed EM potential precursors may permit a real-time and step-by-step monitoring of the EQ generation is tested.

Current challenges for pre-earthquake electromagnetic emissions: shedding light from micro-scale plastic flow, granular packings, phase transitions and self-affinity notion of fracture process

Directory of Open Access Journals (Sweden)

K. Eftaxias

2013-10-01

Full Text Available Are there credible electromagnetic (EM potential earthquake (EQ precursors? This a question debated in the scientific community and there may be legitimate reasons for the critical views. The negative view concerning the existence of EM potential precursors is enhanced by features that accompany their observation which are considered as paradox ones, namely, these signals: (i are not observed at the time of EQs occurrence and during the aftershock period, (ii are not accompanied by large precursory strain changes, (iii are not accompanied by simultaneous geodetic or seismological precursors and (iv their traceability is considered problematic. In this work, the detected candidate EM potential precursors are studied through a shift in thinking towards the basic science findings relative to granular packings, micron-scale plastic flow, interface depinning, fracture size effects, concepts drawn from phase transitions, self-affine notion of fracture and faulting process, universal features of fracture surfaces, recent high quality laboratory studies, theoretical models and numerical simulations. We try to contribute to the establishment of strict criteria for the definition of an emerged EM anomaly as a possibly EQ-related one, and to the explanation of potential precursory EM features which have been considered as paradoxes. A three-stage model for EQ generation by means of pre-EQ fracture-induced EM emissions is proposed. The claim that the observed EM potential precursors may permit a real-time and step-by-step monitoring of the EQ generation is tested.

Real-Time Prediction of Temperature Elevation During Robotic Bone Drilling Using the Torque Signal.

Science.gov (United States)

Feldmann, Arne; Gavaghan, Kate; Stebinger, Manuel; Williamson, Tom; Weber, Stefan; Zysset, Philippe

2017-09-01

Bone drilling is a surgical procedure commonly required in many surgical fields, particularly orthopedics, dentistry and head and neck surgeries. While the long-term effects of thermal bone necrosis are unknown, the thermal damage to nerves in spinal or otolaryngological surgeries might lead to partial paralysis. Previous models to predict the temperature elevation have been suggested, but were not validated or have the disadvantages of computation time and complexity which does not allow real time predictions. Within this study, an analytical temperature prediction model is proposed which uses the torque signal of the drilling process to model the heat production of the drill bit. A simple Green's disk source function is used to solve the three dimensional heat equation along the drilling axis. Additionally, an extensive experimental study was carried out to validate the model. A custom CNC-setup with a load cell and a thermal camera was used to measure the axial drilling torque and force as well as temperature elevations. Bones with different sets of bone volume fraction were drilled with two drill bits ([Formula: see text]1.8 mm and [Formula: see text]2.5 mm) and repeated eight times. The model was calibrated with 5 of 40 measurements and successfully validated with the rest of the data ([Formula: see text]C). It was also found that the temperature elevation can be predicted using only the torque signal of the drilling process. In the future, the model could be used to monitor and control the drilling process of surgeries close to vulnerable structures.

Monte Carlo simulation of a coded-aperture thermal neutron camera

International Nuclear Information System (INIS)

Dioszegi, I.; Salwen, C.; Forman, L.

2011-01-01

We employed the MCNPX Monte Carlo code to simulate image formation in a coded-aperture thermal-neutron camera. The camera, developed at Brookhaven National Laboratory (BNL), consists of a 20 x 17 cm"2 active area "3He-filled position-sensitive wire chamber in a cadmium enclosure box. The front of the box is a coded-aperture cadmium mask (at present with three different resolutions). We tested the detector experimentally with various arrangements of moderated point-neutron sources. The purpose of using the Monte Carlo modeling was to develop an easily modifiable model of the device to predict the detector's behavior using different mask patterns, and also to generate images of extended-area sources or large numbers (up to ten) of them, that is important for nonproliferation and arms-control verification, but difficult to achieve experimentally. In the model, we utilized the advanced geometry capabilities of the MCNPX code to simulate the coded aperture mask. Furthermore, the code simulated the production of thermal neutrons from fission sources surrounded by a thermalizer. With this code we also determined the thermal-neutron shadow cast by the cadmium mask; the calculations encompassed fast- and epithermal-neutrons penetrating into the detector through the mask. Since the process of signal production in "3He-filled position-sensitive wire chambers is well known, we omitted this part from our modeling. Simplified efficiency values were used for the three (thermal, epithermal, and fast) neutron-energy regions. Electronic noise and the room's background were included as a uniform irradiation component. We processed the experimental- and simulated-images using identical LabVIEW virtual instruments. (author)

Thermal conductivity and thermal rectification in unzipped carbon nanotubes

International Nuclear Information System (INIS)

Ni Xiaoxi; Li Baowen; Zhang Gang

2011-01-01

We study the thermal transport in completely unzipped carbon nanotubes, which are called graphene nanoribbons, partially unzipped carbon nanotubes, which can be seen as carbon-nanotube-graphene-nanoribbon junctions, and carbon nanotubes by using molecular dynamics simulations. It is found that the thermal conductivity of a graphene nanoribbon is much less than that of its perfect carbon nanotube counterparts because of the localized phonon modes at the boundary. A partially unzipped carbon nanotube has the lowest thermal conductivity due to additional localized modes at the junction region. More strikingly, a significant thermal rectification effect is observed in both partially unzipped armchair and zigzag carbon nanotubes. Our results suggest that carbon-nanotube-graphene-nanoribbon junctions can be used in thermal energy control.

Thermal Properties of Carbon Nanotube–Copper Composites for Thermal Management Applications

Directory of Open Access Journals (Sweden)

Jia Chengchang

2010-01-01

Full Text Available Abstract Carbon nanotube–copper (CNT/Cu composites have been successfully synthesized by means of a novel particles-compositing process followed by spark plasma sintering (SPS technique. The thermal conductivity of the composites was measured by a laser flash technique and theoretical analyzed using an effective medium approach. The experimental results showed that the thermal conductivity unusually decreased after the incorporation of CNTs. Theoretical analyses revealed that the interfacial thermal resistance between the CNTs and the Cu matrix plays a crucial role in determining the thermal conductivity of bulk composites, and only small interfacial thermal resistance can induce a significant degradation in thermal conductivity for CNT/Cu composites. The influence of sintering condition on the thermal conductivity depended on the combined effects of multiple factors, i.e. porosity, CNTs distribution and CNT kinks or twists. The composites sintered at 600°C for 5 min under 50 MPa showed the maximum thermal conductivity. CNT/Cu composites are considered to be a promising material for thermal management applications.

Optically Transparent Thermally Insulating Silica Aerogels for Solar Thermal Insulation.

Science.gov (United States)

Günay, A Alperen; Kim, Hannah; Nagarajan, Naveen; Lopez, Mateusz; Kantharaj, Rajath; Alsaati, Albraa; Marconnet, Amy; Lenert, Andrej; Miljkovic, Nenad

2018-04-18

Rooftop solar thermal collectors have the potential to meet residential heating demands if deployed efficiently at low solar irradiance (i.e., 1 sun). The efficiency of solar thermal collectors depends on their ability to absorb incoming solar energy and minimize thermal losses. Most techniques utilize a vacuum gap between the solar absorber and the surroundings to eliminate conduction and convection losses, in combination with surface coatings to minimize reradiation losses. Here, we present an alternative approach that operates at atmospheric pressure with simple, black, absorbing surfaces. Silica based aerogels coated on black surfaces have the potential to act as simple and inexpensive solar thermal collectors because of their high transmission to solar radiation and low transmission to thermal radiation. To demonstrate their heat-trapping properties, we fabricated tetramethyl orthosilicate-based silica aerogels. A hydrophilic aerogel with a thickness of 1 cm exhibited a solar-averaged transmission of 76% and thermally averaged transmission of ≈1% (at 100 °C). To minimize unwanted solar absorption by O-H groups, we functionalized the aerogel to be hydrophobic, resulting in a solar-averaged transmission of 88%. To provide a deeper understanding of the link between aerogel properties and overall efficiency, we developed a coupled radiative-conductive heat transfer model and used it to predict solar thermal performance. Instantaneous solar thermal efficiencies approaching 55% at 1 sun and 80 °C were predicted. This study sheds light on the applicability of silica aerogels on black coatings for solar thermal collectors and offers design priorities for next-generation solar thermal aerogels.

THERMAL CONSOLIDATION OF LAYERED POROUS HALF-SPACE TO VARIABLE THERMAL LOADING

Institute of Scientific and Technical Information of China (English)

BAI Bing

2006-01-01

An analytical method was derived for the thermal consolidation of layered,saturated porous half-space to variable thermal loading with time. In the coupled governing equations of linear thermoelastic media, the influences of thermo-osmosis effect and thermal filtration effect were introduced. Solutions in Laplace transform space were first obtained and then numerically inverted. The responses of a double-layered porous space subjected to exponential decaying thermal loading were studied. The influences of the differences between the properties of the two layers (e.g., the coefficient of thermal consolidation, elastic modulus) on thermal consolidation were discussed. The studies show that the coupling effects of displacement and stress fields on temperature field can be completely neglected, however, thc thermo-osmosis effect has an obvious influence on thermal responses.

Performance test of Si PIN photodiode line scanner for thermal neutron detection

Energy Technology Data Exchange (ETDEWEB)

Totsuka, Daisuke, E-mail: totsuka@imr.tohoku.ac.jp [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Nihon Kessho Kogaku Co., Ltd., 810-5 Nobe-cho Tatebayashi, Gunma 374-0047 (Japan); Yanagida, Takayuki [New Industry Creation Hatchery Center (NICHe) 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Fukuda, Kentaro; Kawaguchi, Noriaki [Tokuyama Corp., 3 Shibuya Shibuya-ku, Tokyo 150-8383 (Japan); Fujimoto, Yutaka [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Pejchal, Jan [Institute of Physics AS CR, Cukrovarnicka 10, Prague 6, 162-53 (Czech Republic); Yokota, Yuui [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Yoshikawa, Akira [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); New Industry Creation Hatchery Center (NICHe) 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan)

2011-12-11

Thermal neutron imaging using Si PIN photodiode line scanner and Eu-doped LiCaAlF{sub 6} crystal scintillator has been developed. The pixel dimensions of photodiode are 1.18 mm (width) Multiplication-Sign 3.8 mm (length) with 0.4 mm gap and the module has 192 channels in linear array. The emission peaks of Eu-doped LiCaAlF{sub 6} after thermal neutron excitation are placed at 370 and 590 nm, and the corresponding photon sensitivities of photodiode are 0.04 and 0.34 A/W, respectively. Polished scintillator blocks with a size of 1.18 mm (width) Multiplication-Sign 3.8 mm (length) Multiplication-Sign 5.0 mm (thickness) were wrapped by several layers of Teflon tapes as a reflector and optically coupled to the photodiodes by silicone grease. JRR-3 MUSASI beam line emitting 13.5 meV thermal neutrons with the flux of 8 Multiplication-Sign 10{sup 5} n/cm{sup 2} s was used for the imaging test. As a subject for imaging, a Cd plate was moved at the speed of 50 mm/s perpendicular to the thermal neutron beam. Analog integration time was set to be 416.6 {mu}s, then signals were converted by a delta-sigma A/D converter. After the image processing, we successfully obtained moving Cd plate image under thermal neutron irradiation using PIN photodiode line scanner coupled with Eu-doped LiCaAlF{sub 6} scintillator.

Performance test of Si PIN photodiode line scanner for thermal neutron detection

International Nuclear Information System (INIS)

Totsuka, Daisuke; Yanagida, Takayuki; Fukuda, Kentaro; Kawaguchi, Noriaki; Fujimoto, Yutaka; Pejchal, Jan; Yokota, Yuui; Yoshikawa, Akira

2011-01-01

Thermal neutron imaging using Si PIN photodiode line scanner and Eu-doped LiCaAlF 6 crystal scintillator has been developed. The pixel dimensions of photodiode are 1.18 mm (width)×3.8 mm (length) with 0.4 mm gap and the module has 192 channels in linear array. The emission peaks of Eu-doped LiCaAlF 6 after thermal neutron excitation are placed at 370 and 590 nm, and the corresponding photon sensitivities of photodiode are 0.04 and 0.34 A/W, respectively. Polished scintillator blocks with a size of 1.18 mm (width)×3.8 mm (length)×5.0 mm (thickness) were wrapped by several layers of Teflon tapes as a reflector and optically coupled to the photodiodes by silicone grease. JRR-3 MUSASI beam line emitting 13.5 meV thermal neutrons with the flux of 8×10 5 n/cm 2 s was used for the imaging test. As a subject for imaging, a Cd plate was moved at the speed of 50 mm/s perpendicular to the thermal neutron beam. Analog integration time was set to be 416.6 μs, then signals were converted by a delta-sigma A/D converter. After the image processing, we successfully obtained moving Cd plate image under thermal neutron irradiation using PIN photodiode line scanner coupled with Eu-doped LiCaAlF 6 scintillator.

From thermal boredom to thermal pleasure: a brief literature review

Directory of Open Access Journals (Sweden)

Christhina Candido

Full Text Available The most recent review of the ASHRAE Standard 55 (2010 incorporates the dialectic between static and adaptive approaches to thermal comfort by proposing different recommendations for airconditioned and naturally ventilated buildings. Particularly in naturally ventilated buildings, this standard aligns with three important topics in research field of thermal comfort during the last decades: (i air movement enhancement versus draft, (ii control availability and its impact on occupants' satisfaction, and (iii the search for thermal pleasure. This paper presents the rationale behind these three research topics and discusses its positive influence when moving from thermal comfort towards thermal pleasure.

Industrial application of thermal image processing and thermal control

Science.gov (United States)

Kong, Lingxue

2001-09-01

Industrial application of infrared thermography is virtually boundless as it can be used in any situations where there are temperature differences. This technology has particularly been widely used in automotive industry for process evaluation and system design. In this work, thermal image processing technique will be introduced to quantitatively calculate the heat stored in a warm/hot object and consequently, a thermal control system will be proposed to accurately and actively manage the thermal distribution within the object in accordance with the heat calculated from the thermal images.

The role of MFM signal in mark size measurement in probe-based magnetic recording on CoNi/Pt multilayers

International Nuclear Information System (INIS)

Zhang Li; Bain, James A.; Zhu Jiangang; Abelmann, Leon; Onoue, Takahiro

2007-01-01

A method of heat-assisted magnetic recording (HAMR) potentially suitable for probe-based storage systems is characterized. Magnetic marks were formed by a scanning tunneling microscopy (STM)-based thermal magnetic mechanism on a perpendicular CoNi/Pt multilayered film. Magnetic force microscopy (MFM) was applied to display those marks. The MFM signal is dependent of the lift-height during MFM scanning: smaller lift-height leads to higher resolution of the MFM image and a double-peak signal line, while higher lift-height leads to lower resolution and a single-peak signal line. Theoretical calculation of the magnetic field from the mark was executed. It agrees well with experiments, and demonstrates the method of mark size measurement in perpendicular media: full-width half-maximum (FWHM) of the measured MFM signal

Preparation, thermal properties and thermal reliabilities of microencapsulated n-octadecane with acrylic-based polymer shells for thermal energy storage

International Nuclear Information System (INIS)

Qiu, Xiaolin; Song, Guolin; Chu, Xiaodong; Li, Xuezhu; Tang, Guoyi

2013-01-01

Highlights: ► n-Octadecane was encapsulated by p(butyl methacrylate) (PBMA) and p(butyl acrylate). ► Microcapsules using divinylbenzene as crosslinking agent have better quality. ► Microcapsule with butyl methacrylate–divinylbenzene has highest latent heat. ► Microcapsule with butyl methacrylate–divinylbenzene has greatest thermal stability. ► Phase change temperatures and enthalpies of the microcapsules varied little after thermal cycle. - Abstract: Microencapsulation of n-octadecane with crosslinked p(butyl methacrylate) (PBMA) and p(butyl acrylate) (PBA) as shells for thermal energy storage was carried out by a suspension-like polymerization. Divinylbenzene (DVB) and pentaerythritol triacrylate (PETA) were employed as crosslinking agents. The surface morphologies of the microencapsulated phase change materials (microPCMs) were studied by scanning electron microscopy (SEM). Thermal properties, thermal reliabilities and thermal stabilities of the as-prepared microPCMs were investigated by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The microPCMs prepared by using DVB exhibit greater heat capacities and higher thermal stabilities compared with those prepared by using PETA. The thermal resistant temperature of the microPCM with BMA–DVB polymer was up to 248 °C. The phase change temperatures and latent heats of all the as-prepared microcapsules varied little after 1000 thermal cycles.

Recovery in dc and rf performance of off-state step-stressed AlGaN/GaN high electron mobility transistors with thermal annealing

International Nuclear Information System (INIS)

Kim, Byung-Jae; Hwang, Ya-Hsi; Ahn, Shihyun; Zhu, Weidi; Dong, Chen; Lu, Liu; Ren, Fan; Holzworth, M. R.; Jones, Kevin S.; Pearton, Stephen J.; Smith, David J.; Kim, Jihyun; Zhang, Ming-Lan

2015-01-01

The recovery effects of thermal annealing on dc and rf performance of off-state step-stressed AlGaN/GaN high electron mobility transistors were investigated. After stress, reverse gate leakage current and sub-threshold swing increased and drain current on-off ratio decreased. However, these degradations were completely recovered after thermal annealing at 450 °C for 10 mins for devices stressed either once or twice. The trap densities, which were estimated by temperature-dependent drain-current sub-threshold swing measurements, increased after off-state step-stress and were reduced after subsequent thermal annealing. In addition, the small signal rf characteristics of stressed devices were completely recovered after thermal annealing

Evaluation of properties and thermal stress field for thermal barrier coatings

Institute of Scientific and Technical Information of China (English)

王良; 齐红宇; 杨晓光; 李旭

2008-01-01

In order to get thermal stress field of the hot section with thermal barrier coating (TBCs), the thermal conductivity and elastic modulus of top-coat are the physical key properties. The porosity of top-coat was tested and evaluated under different high temperatures. The relationship between the microstructure (porosity of top-coat) and properties of TBCs were analyzed to predict the thermal properties of ceramic top-coat, such as thermal conductivity and elastic modulus. The temperature and stress field of the vane with TBCs were simulated using two sets of thermal conductivity data and elastic modulus, which are from literatures and this work, respectively. The results show that the temperature and stress distributions change with thermal conductivity and elastic modulus. The differences of maximum temperatures and stress are 6.5% and 8.0%, respectively.

A Real-Time Thermal Self-Elimination Method for Static Mode Operated Freestanding Piezoresistive Microcantilever-Based Biosensors

Directory of Open Access Journals (Sweden)

Yu-Fu Ku

2018-02-01

Full Text Available Here, we provide a method and apparatus for real-time compensation of the thermal effect of single free-standing piezoresistive microcantilever-based biosensors. The sensor chip contained an on-chip fixed piezoresistor that served as a temperature sensor, and a multilayer microcantilever with an embedded piezoresistor served as a biomolecular sensor. This method employed the calibrated relationship between the resistance and the temperature of piezoresistors to eliminate the thermal effect on the sensor, including the temperature coefficient of resistance (TCR and bimorph effect. From experimental results, the method was verified to reduce the signal of thermal effect from 25.6 μV/°C to 0.3 μV/°C, which was approximately two orders of magnitude less than that before the processing of the thermal elimination method. Furthermore, the proposed approach and system successfully demonstrated its effective real-time thermal self-elimination on biomolecular detection without any thermostat device to control the environmental temperature. This method realizes the miniaturization of an overall measurement system of the sensor, which can be used to develop portable medical devices and microarray analysis platforms.

Relationships between radon anomalies and seismic parameters in N-W Himalaya, India

International Nuclear Information System (INIS)

Walia, Vivek; Virk, H.S.; Bajwa, B.S.; Sharma, Navjeet

2003-01-01

Radon data accumulated during 1992-1999 in the grid (30-34 deg. N, 74-78 deg. E) in N-W Himalaya have been anlaysed vis a vis seismic data recorded in the same area, supplied by Indian Meteorological Department (IMD) network. In general, there is a positive correlation between the total radon emission and the microseismicity in the area under investigation. The earthquake magnitude has moderate positive correlation with epicentral distance and low positive correlation with amplitude of radon precursory signal, whereas both show low negative correlation between them. Empirical scaling relations are proposed using the best fit straight line from the log-linear graphs between magnitude of the events and log of the product of amplitude of radon anomaly and epicentral distance. The error between the recorded and calculated magnitude is also taken into account. The error range is higher at lower epicentral distances and magnitudes, showing that the local geology and tectonics have predominant influence on radon signals

Genetic Algorithm for Opto-thermal Skin Hydration Depth Profiling Measurements

Science.gov (United States)

Cui, Y.; Xiao, Perry; Imhof, R. E.

2013-09-01

Stratum corneum is the outermost skin layer, and the water content in stratum corneum plays a key role in skin cosmetic properties as well as skin barrier functions. However, to measure the water content, especially the water concentration depth profile, within stratum corneum is very difficult. Opto-thermal emission radiometry, or OTTER, is a promising technique that can be used for such measurements. In this paper, a study on stratum corneum hydration depth profiling by using a genetic algorithm (GA) is presented. The pros and cons of a GA compared against other inverse algorithms such as neural networks, maximum entropy, conjugate gradient, and singular value decomposition will be discussed first. Then, it will be shown how to use existing knowledge to optimize a GA for analyzing the opto-thermal signals. Finally, these latest GA results on hydration depth profiling of stratum corneum under different conditions, as well as on the penetration profiles of externally applied solvents, will be shown.

Outdoor thermal comfort.

Science.gov (United States)

Nikolopoulou, Marialena

2011-06-01

A review of the various approaches in understanding outdoor thermal comfort is presented. The emphasis on field surveys from around the world, particularly across Europe, enables us to understand thermal perception and evaluate outdoor thermal comfort conditions. The consistent low correlations between objective microclimatic variables, subjective thermal sensation and comfort outdoors, internationally, suggest that thermophysiology alone does not adequate describe these relationships. Focusing on the concept of adaptation, it tries to explain how this influences outdoor comfort, enabling us to inhabit and get satisfaction from outdoor spaces throughout the year. Beyond acclimatization and behavioral adaptation, through adjustments in clothing and changes to the metabolic heat, psychological adaptation plays a critical role to ensure thermal comfort and satisfaction with the outdoor environment. Such parameters include recent experiences and expectations; personal choice and perceived control, more important than whether that control is actually exercised; and the need for positive environmental stimulation suggesting that thermal neutrality is not a pre-requisite for thermal comfort. Ultimately, enhancing environmental diversity can influence thermal perception and experience of open spaces.

Wide-range measurement of thermal effusivity using molybdenum thin film with low thermal conductivity for thermal microscopes

Science.gov (United States)

Miyake, Shugo; Matsui, Genzou; Ohta, Hiromichi; Hatori, Kimihito; Taguchi, Kohei; Yamamoto, Suguru

2017-07-01

Thermal microscopes are a useful technology to investigate the spatial distribution of the thermal transport properties of various materials. However, for high thermal effusivity materials, the estimated values of thermophysical parameters based on the conventional 1D heat flow model are known to be higher than the values of materials in the literature. Here, we present a new procedure to solve the problem which calculates the theoretical temperature response with the 3D heat flow and measures reference materials which involve known values of thermal effusivity and heat capacity. In general, a complicated numerical iterative method and many thermophysical parameters are required for the calculation in the 3D heat flow model. Here, we devised a simple procedure by using a molybdenum (Mo) thin film with low thermal conductivity on the sample surface, enabling us to measure over a wide thermal effusivity range for various materials.

Using diurnal temperature signals to infer vertical groundwater-surface water exchange

Science.gov (United States)

Irvine, Dylan J.; Briggs, Martin A.; Lautz, Laura K.; Gordon, Ryan P.; McKenzie, Jeffrey M.; Cartwright, Ian

2017-01-01

Heat is a powerful tracer to quantify fluid exchange between surface water and groundwater. Temperature time series can be used to estimate pore water fluid flux, and techniques can be employed to extend these estimates to produce detailed plan-view flux maps. Key advantages of heat tracing include cost-effective sensors and ease of data collection and interpretation, without the need for expensive and time-consuming laboratory analyses or induced tracers. While the collection of temperature data in saturated sediments is relatively straightforward, several factors influence the reliability of flux estimates that are based on time series analysis (diurnal signals) of recorded temperatures. Sensor resolution and deployment are particularly important in obtaining robust flux estimates in upwelling conditions. Also, processing temperature time series data involves a sequence of complex steps, including filtering temperature signals, selection of appropriate thermal parameters, and selection of the optimal analytical solution for modeling. This review provides a synthesis of heat tracing using diurnal temperature oscillations, including details on optimal sensor selection and deployment, data processing, model parameterization, and an overview of computing tools available. Recent advances in diurnal temperature methods also provide the opportunity to determine local saturated thermal diffusivity, which can improve the accuracy of fluid flux modeling and sensor spacing, which is related to streambed scour and deposition. These parameters can also be used to determine the reliability of flux estimates from the use of heat as a tracer.

Thermal energy storage devices, systems, and thermal energy storage device monitoring methods

Science.gov (United States)

Tugurlan, Maria; Tuffner, Francis K; Chassin, David P.

2016-09-13

Thermal energy storage devices, systems, and thermal energy storage device monitoring methods are described. According to one aspect, a thermal energy storage device includes a reservoir configured to hold a thermal energy storage medium, a temperature control system configured to adjust a temperature of the thermal energy storage medium, and a state observation system configured to provide information regarding an energy state of the thermal energy storage device at a plurality of different moments in time.

Thermal analysis of annular fins with temperature-dependent thermal properties

Institute of Scientific and Technical Information of China (English)

I. G. AKSOY

2013-01-01

The thermal analysis of the annular rectangular profile fins with variable thermal properties is investigated by using the homotopy analysis method (HAM). The thermal conductivity and heat transfer coefficient are assumed to vary with a linear and power-law function of temperature, respectively. The effects of the thermal-geometric fin parameter and the thermal conductivity parameter variations on the temperature distribution and fin efficiency are investigated for different heat transfer modes. Results from the HAM are compared with numerical results of the finite difference method (FDM). It can be seen that the variation of dimensionless parameters has a significant effect on the temperature distribution and fin efficiency.

Physiological Responses to Thermal Stress and Exercise

Science.gov (United States)

Iyota, Hiroyuki; Ohya, Akira; Yamagata, Junko; Suzuki, Takashi; Miyagawa, Toshiaki; Kawabata, Takashi

The simple and noninvasive measuring methods of bioinstrumentation in humans is required for optimization of air conditioning and management of thermal environments, taking into consideration the individual specificity of the human body as well as the stress conditions affecting each. Changes in human blood circulation were induced with environmental factors such as heat, cold, exercise, mental stress, and so on. In this study, the physiological responses of human body to heat stress and exercise were investigated in the initial phase of the developmental research. We measured the body core and skin temperatures, skin blood flow, and pulse wave as the indices of the adaptation of the cardiovascular system. A laser Doppler skin blood flowmetry using an optical-sensor with a small portable data logger was employed for the measurement. These results reveal the heat-stress and exercise-induced circulatory responses, which are under the control of the sympathetic nerve system. Furthermore, it was suggested that the activity of the sympathetic nervous system could be evaluated from the signals of the pulse wave included in the signals derived from skin blood flow by means of heart rate variability assessments and detecting peak heights of velocity-plethysmogram.

Thermal morphing anisogrid smart space structures: thermal isolation design and linearity evaluation

Science.gov (United States)

Phoenix, Austin A.

2017-04-01

To meet the requirements for the next generation of space missions, a paradigm shift is required from current structures that are static, heavy and stiff, toward innovative structures that are adaptive, lightweight, versatile, and intelligent. A novel morphing structure, the thermally actuated anisogrid morphing boom, can be used to meet the design requirements by making the primary structure actively adapt to the on-orbit environment. The anisogrid structure is able to achieve high precision morphing control through the intelligent application of thermal gradients. This active primary structure improves structural and thermal stability performance, reduces mass, and enables new mission architectures. This effort attempts to address limits to the author's previous work by incorporating the impact of thermal coupling that was initially neglected. This paper introduces a thermally isolated version of the thermal morphing anisogrid structure in order to address the thermal losses between active members. To evaluate the isolation design the stiffness and thermal conductivity of these isolating interfaces need to be addressed. This paper investigates the performance of the thermal morphing system under a variety of structural and thermal isolation interface properties.

Thermalization without eigenstate thermalization hypothesis after a quantum quench.

Science.gov (United States)

Mori, Takashi; Shiraishi, Naoto

2017-08-01

Nonequilibrium dynamics of a nonintegrable system without the eigenstate thermalization hypothesis is studied. It is shown that, in the thermodynamic limit, this model thermalizes after an arbitrary quantum quench at finite temperature, although it does not satisfy the eigenstate thermalization hypothesis. In contrast, when the system size is finite and the temperature is low enough, the system may not thermalize. In this case, the steady state is well described by the generalized Gibbs ensemble constructed by using highly nonlocal conserved quantities. We also show that this model exhibits prethermalization, in which the prethermalized state is characterized by nonthermal energy eigenstates.

Thermal Design and Thermal Behaviour of Radio Telescopes and their Enclosures

CERN Document Server

Greve, Albert

2010-01-01

Radio telescopes as well as communication antennas operate under the influence of gravity, temperature and wind. Among those, temperature influences may degrade the performance of a radio telescope through transient changes of the focus, pointing, path length and sensitivity, often in an unpredictable way. Thermal Design and Thermal Behaviour of Radio Telescopes and their Enclosures reviews the design and construction principles of radio telescopes in view of thermal aspects and heat transfer with the variable thermal environment; it explains supporting thermal model calculations and the application and efficiency of thermal protection and temperature control; it presents many measurements illustrating the thermal behaviour of telescopes in the environment of their observatory sites. The book benefits scientists and radio/communication engineers, telescope designers and construction firms as well as telescope operators, observatory staff, but also the observing astronomer who is directly confronted with the t...

Preparation, thermal properties and thermal reliabilities of microencapsulated n-octadecane with acrylic-based polymer shells for thermal energy storage

Energy Technology Data Exchange (ETDEWEB)

Qiu, Xiaolin [Advanced Materials Institute and Clearer Production Key Laboratory, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China); Key Laboratory of Advanced Materials, Department of Materials Science and Engineering, Tsinghua University, Haidian District, Beijing 100084 (China); Song, Guolin; Chu, Xiaodong; Li, Xuezhu [Advanced Materials Institute and Clearer Production Key Laboratory, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China); Tang, Guoyi, E-mail: tanggy@tsinghua.edu.cn [Advanced Materials Institute and Clearer Production Key Laboratory, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China); Key Laboratory of Advanced Materials, Department of Materials Science and Engineering, Tsinghua University, Haidian District, Beijing 100084 (China)

2013-01-10

Highlights: Black-Right-Pointing-Pointer n-Octadecane was encapsulated by p(butyl methacrylate) (PBMA) and p(butyl acrylate). Black-Right-Pointing-Pointer Microcapsules using divinylbenzene as crosslinking agent have better quality. Black-Right-Pointing-Pointer Microcapsule with butyl methacrylate-divinylbenzene has highest latent heat. Black-Right-Pointing-Pointer Microcapsule with butyl methacrylate-divinylbenzene has greatest thermal stability. Black-Right-Pointing-Pointer Phase change temperatures and enthalpies of the microcapsules varied little after thermal cycle. - Abstract: Microencapsulation of n-octadecane with crosslinked p(butyl methacrylate) (PBMA) and p(butyl acrylate) (PBA) as shells for thermal energy storage was carried out by a suspension-like polymerization. Divinylbenzene (DVB) and pentaerythritol triacrylate (PETA) were employed as crosslinking agents. The surface morphologies of the microencapsulated phase change materials (microPCMs) were studied by scanning electron microscopy (SEM). Thermal properties, thermal reliabilities and thermal stabilities of the as-prepared microPCMs were investigated by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The microPCMs prepared by using DVB exhibit greater heat capacities and higher thermal stabilities compared with those prepared by using PETA. The thermal resistant temperature of the microPCM with BMA-DVB polymer was up to 248 Degree-Sign C. The phase change temperatures and latent heats of all the as-prepared microcapsules varied little after 1000 thermal cycles.

THERMAL PLASMA IN THE GIANT LOBES OF THE RADIO GALAXY CENTAURUS A

Energy Technology Data Exchange (ETDEWEB)

O' Sullivan, S. P.; Feain, I. J.; McClure-Griffiths, N. M.; Ekers, R. D.; Carretti, E. [CSIRO Astronomy and Space Science, ATNF, P.O. Box 76, Epping, NSW 1710 (Australia); Robishaw, T. [Herzberg Institute of Astrophysics, Dominion Radio Astrophysical Observatory, P.O. Box 248, Penticton, BC V2A 6J9 (Canada); Mao, S. A. [National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801 (United States); Gaensler, B. M.; Bland-Hawthorn, J. [Sydney Institute for Astronomy, School of Physics, The University of Sydney, NSW 2006 (Australia); Stawarz, L. [Institute of Space and Astronautical Science, JAXA, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan)

2013-02-20

We present a Faraday rotation measure (RM) study of the diffuse, polarized, radio emission from the giant lobes of the nearest radio galaxy, Centaurus A. After removal of the smooth Galactic foreground RM component, using an ensemble of background source RMs located outside the giant lobes, we are left with a residual RM signal associated with the giant lobes. We find that the most likely origin of this residual RM is from thermal material mixed throughout the relativistic lobe plasma. The alternative possibility of a thin-skin/boundary layer of magnetoionic material swept up by the expansion of the lobes is highly unlikely since it requires, at least, an order of magnitude enhancement of the swept-up gas over the expected intragroup density on these scales. Strong depolarization observed from 2.3 to 0.96 GHz also supports the presence of a significant amount of thermal gas within the lobes; although depolarization solely due to RM fluctuations in a foreground Faraday screen on scales smaller than the beam cannot be ruled out. Considering the internal Faraday rotation scenario, we find a thermal gas number density of {approx}10{sup -4} cm{sup -3}, implying a total gas mass of {approx}10{sup 10} M {sub Sun} within the lobes. The thermal pressure associated with this gas (with temperature kT {approx} 0.5 keV, obtained from recent X-ray results) is approximately equal to the non-thermal pressure, indicating that over the volume of the lobes, there is approximate equipartition between the thermal gas, radio-emitting electrons, and magnetic field (and potentially any relativistic protons present).

Retrieving the thermal diffusivity and effusivity of solids from the same frequency scan using the front photopyroelectric technique

International Nuclear Information System (INIS)

Salazar, Agustín; Oleaga, Alberto; Mendioroz, Arantza; Apiñaniz, Estibaliz

2017-01-01

The photopyroelectric (PPE) technique in the front configuration consists in illuminating one surface of a pyroelectric slab while the other surface is in contact with the test sample. This method has been widely used to measure the thermal effusivity of liquids. Recently, it has been extended to measure the thermal effusivity of solids, by taking into account the influence of the coupling fluid layer used to guarantee the thermal contact. In both cases, the sample (liquid or solid) must be very thick. In this work, we propose a classical frequency scan of a thin sample slab to retrieve the thermal diffusivity and effusivity simultaneously. We use the amplitude and the phase of the front PPE signal, which depend on four parameters: the sample diffusivity and effusivity, the coupling fluid thickness and the coefficient of heat losses. It is demonstrated that the four quantities are not correlated. PPE measurements performed on a set of calibrated solids confirm the ability of the method to obtain the thermal diffusivity and effusivity of solids accurately. (paper)

Thermal insulation

International Nuclear Information System (INIS)

Aspden, G.J.; Howard, R.S.

1988-01-01

The patent concerns high temperature thermal insulation of large vessels, such as the primary vessel of a liquid metal cooled nuclear reactor. The thermal insulation consists of multilayered thermal insulation modules, and each module comprises a number of metal sheet layers sandwiched between a back and front plate. The layers are linked together by straps and clips to control the thickness of the module. (U.K.)

Exploration of porous SiC nanostructures as thermal insulator with high thermal stability and low thermal conductivity

Institute of Scientific and Technical Information of China (English)

Peng; WAN; Jingyang; WANG

2016-01-01

The crucial challenge for current nanoscale thermal insulation materials,such as Al2O3 and SiO2 aerogel composites,is to solve the trade-off between extremely low thermal conductivity and unsatisfied thermal stability.Typical high-temperature ceramic SiC possesses excellent mechanical properties and

Quantum thermal rectification to design thermal diodes and transistors

Energy Technology Data Exchange (ETDEWEB)

Joulain, Karl; Ezzahri, Younes; Ordonez-Miranda, Jose [Univ. de Poitiers, Futuroscope Chasseneuil (France). Inst. Pprime, CNRS

2017-05-01

We study in this article how heat can be exchanged between two-level systems, each of them being coupled to a thermal reservoir. Calculations are performed solving a master equation for the density matrix using the Born-Markov approximation. We analyse the conditions for which a thermal diode and a thermal transistor can be obtained as well as their optimisation.

Electrical potential changes and acoustic emissions generated by fracture and fluid flow during experimental triaxial rock deformation

Science.gov (United States)

Clint, Oswald Conan

Natural electrical potential signals have been recorded from numerous seismically active areas around the world and therefore have been proposed as a potential earthquake prediction tool. The streaming potential is being used to locate sub-surface water reservoirs, to monitor steam fronts during enhanced oil recovery techniques, and to delineate the anisotropy of fractures in geothermal and oil reservoirs. The generating mechanism for these signals is still unclear although plausible theories include: - Piezoelectric fields produced through stress changes on piezoelectric materials, such as quartz, found in many rocks. - Electrokinetic currents induced through a pressure gradient and caused by electrical charge transport within a moving fluid. - Less well-established theories for instance involving current carrying mobile O' charges. To investigate the relative significance of these mechanisms, I have measured the direct current electrical potential and acoustic emissions during constant strain rate rock deformation under simulated crustal conditions of pressure and pore fluid pressure. Some sixty-one experiments were done on rock samples of quartz rich Darley Dale and Bentheim sandstone and quartz free basalt from Iceland. A computer and servo-controlled conventional triaxial cell was used to deform dry, water-saturated and brine-saturated rock samples at confining pressures between 20 and 200MPa, pore fluid pressures between 10 and 50MPa and strain rates from 10-4 s-1 to 10-6 s-1 I identify the primary sources of the electrical potential signals as being generated by (i) piezoelectricity in dry sandstone experiments and (ii) electrokinetic effect in saturated basalt experiments. I show that electrical potential signals from the other proposed methods are not detectable above the background noise level. It can therefore be argued that the electrokinetic effect is the main electrical potential generating mechanism within the upper crust.Both precursory and

Human and natural influences on the changing thermal structure of the atmosphere.

Science.gov (United States)

Santer, Benjamin D; Painter, Jeffrey F; Bonfils, Céline; Mears, Carl A; Solomon, Susan; Wigley, Tom M L; Gleckler, Peter J; Schmidt, Gavin A; Doutriaux, Charles; Gillett, Nathan P; Taylor, Karl E; Thorne, Peter W; Wentz, Frank J

2013-10-22

Since the late 1970s, satellite-based instruments have monitored global changes in atmospheric temperature. These measurements reveal multidecadal tropospheric warming and stratospheric cooling, punctuated by short-term volcanic signals of reverse sign. Similar long- and short-term temperature signals occur in model simulations driven by human-caused changes in atmospheric composition and natural variations in volcanic aerosols. Most previous comparisons of modeled and observed atmospheric temperature changes have used results from individual models and individual observational records. In contrast, we rely on a large multimodel archive and multiple observational datasets. We show that a human-caused latitude/altitude pattern of atmospheric temperature change can be identified with high statistical confidence in satellite data. Results are robust to current uncertainties in models and observations. Virtually all previous research in this area has attempted to discriminate an anthropogenic signal from internal variability. Here, we present evidence that a human-caused signal can also be identified relative to the larger "total" natural variability arising from sources internal to the climate system, solar irradiance changes, and volcanic forcing. Consistent signal identification occurs because both internal and total natural variability (as simulated by state-of-the-art models) cannot produce sustained global-scale tropospheric warming and stratospheric cooling. Our results provide clear evidence for a discernible human influence on the thermal structure of the atmosphere.

Thermal performance and heat transport in aquifer thermal energy storage

Science.gov (United States)

Sommer, W. T.; Doornenbal, P. J.; Drijver, B. C.; van Gaans, P. F. M.; Leusbrock, I.; Grotenhuis, J. T. C.; Rijnaarts, H. H. M.

2014-01-01

Aquifer thermal energy storage (ATES) is used for seasonal storage of large quantities of thermal energy. Due to the increasing demand for sustainable energy, the number of ATES systems has increased rapidly, which has raised questions on the effect of ATES systems on their surroundings as well as their thermal performance. Furthermore, the increasing density of systems generates concern regarding thermal interference between the wells of one system and between neighboring systems. An assessment is made of (1) the thermal storage performance, and (2) the heat transport around the wells of an existing ATES system in the Netherlands. Reconstruction of flow rates and injection and extraction temperatures from hourly logs of operational data from 2005 to 2012 show that the average thermal recovery is 82 % for cold storage and 68 % for heat storage. Subsurface heat transport is monitored using distributed temperature sensing. Although the measurements reveal unequal distribution of flow rate over different parts of the well screen and preferential flow due to aquifer heterogeneity, sufficient well spacing has avoided thermal interference. However, oversizing of well spacing may limit the number of systems that can be realized in an area and lower the potential of ATES.

The signaling lipid sphingosine 1-phosphate regulates mechanical pain

Science.gov (United States)

Hill, Rose Z; Hoffman, Benjamin U; Morita, Takeshi; Campos, Stephanie M; Lumpkin, Ellen A; Brem, Rachel B

2018-01-01

Somatosensory neurons mediate responses to diverse mechanical stimuli, from innocuous touch to noxious pain. While recent studies have identified distinct populations of A mechanonociceptors (AMs) that are required for mechanical pain, the molecular underpinnings of mechanonociception remain unknown. Here, we show that the bioactive lipid sphingosine 1-phosphate (S1P) and S1P Receptor 3 (S1PR3) are critical regulators of acute mechanonociception. Genetic or pharmacological ablation of S1PR3, or blockade of S1P production, significantly impaired the behavioral response to noxious mechanical stimuli, with no effect on responses to innocuous touch or thermal stimuli. These effects are mediated by fast-conducting A mechanonociceptors, which displayed a significant decrease in mechanosensitivity in S1PR3 mutant mice. We show that S1PR3 signaling tunes mechanonociceptor excitability via modulation of KCNQ2/3 channels. Our findings define a new role for S1PR3 in regulating neuronal excitability and establish the importance of S1P/S1PR3 signaling in the setting of mechanical pain thresholds. PMID:29561262

Input/output Buffer based Vedic Multiplier Design for Thermal Aware Energy Efficient Digital Signal Processing on 28nm FPGA

DEFF Research Database (Denmark)

Goswami, Kavita; Pandey, Bishwajeet; Hussain, Dil muhammed Akbar

2016-01-01

Multiplier is used for multiplication of a signal and a constant in digital signal processing (DSP). 28nm technology based Vedic multiplier is implemented with use of VHDL HDL, Xilinx ISE, Kintex-7 FPGA and XPower Analyzer. Vedic multiplier gain speed improvements by parallelizing the generation...... Programmable Gate Array (FPGA) in order to reduce the development cost. The development cost for Application Specific Integrated Circuits (ASICs) are high in compare to FPGA. Selection of the most energy efficient IO standards in place of signal gating is the main design methodology for design of energy...... efficient Vedic multiplier.There is 68.51%, 69.86%, 74.65%, and 78.39% contraction in total power of Vedic multiplier on 28nm Kintex-7 FPGA, when we use HSTL_II in place of HSTL_II_DCI_18 at 56.7oC, 53.5oC, 40oC and 21oC respectively....

Thermal conductivity of technetium

International Nuclear Information System (INIS)

Minato, K.; Serizawa, H.; Fukuda, K.

1998-01-01

The thermal diffusivity of technetium was measured on a disk sample of 5 mm in diameter and 1 mm in thickness by the laser flash method from room temperature to 1173 K, and the thermal conductivity was determined by the measured thermal diffusivity and density, and the reported specific heat capacity. The thermal diffusivity of technetium decreases with increasing temperature though it is almost constant above 600 K. The thermal conductivity of technetium shows a minimum around 400 K, above which the thermal conductivity increases with temperature. The electronic and phonon components of the thermal conductivity were evaluated approximately. The increase in the thermal conductivity of technetium with temperature is due to the increase in the electronic component. (orig.)

Detecting infrared luminescence and non-chemical signaling of living cells: single cell mid-IR spectroscopy in cryogenic environments

Science.gov (United States)

Pereverzev, Sergey

2017-02-01

Many life-relevant interaction energies are in IR range, and it is reasonable to believe that some biochemical reactions inside cells can results in emission of IR photons. Cells can use this emission for non-chemical and non-electrical signaling. Detecting weak infrared radiation from live cells is complicated because of strong thermal radiation background and absorption of radiation by tissues. A microfluidic device with live cells inside a vacuum cryogenic environment should suppress this background, and thereby permit observation of live cell auto-luminescence or signaling in the IR regime. One can make IR-transparent windows not emitting in this range, so only the cell and a small amount of liquid around it will emit infrared radiation. Currently mid-IR spectroscopy of single cells requires the use of a synchrotron source to measure absorption or reflection spectra. Decreasing of thermal radiation background will allow absorption and reflection spectroscopy of cells without using synchrotron light. Moreover, cell auto-luminescence can be directly measured. The complete absence of thermal background radiation for cryogenically cooled samples allows the use IR photon-sensitive detectors and obtaining single molecule sensitivity in IR photo-luminescence measurements. Due to low photon energies, photo-luminescence measurements will be non-distractive for pressures samples. The technique described here is based upon US patent 9366574.

Improved methods for signal processing in measurements of mercury by Tekran® 2537A and 2537B instruments

Science.gov (United States)

Ambrose, Jesse L.

2017-12-01

Atmospheric Hg measurements are commonly carried out using Tekran® Instruments Corporation's model 2537 Hg vapor analyzers, which employ gold amalgamation preconcentration sampling and detection by thermal desorption (TD) and atomic fluorescence spectrometry (AFS). A generally overlooked and poorly characterized source of analytical uncertainty in those measurements is the method by which the raw Hg atomic fluorescence (AF) signal is processed. Here I describe new software-based methods for processing the raw signal from the Tekran® 2537 instruments, and I evaluate the performances of those methods together with the standard Tekran® internal signal processing method. For test datasets from two Tekran® instruments (one 2537A and one 2537B), I estimate that signal processing uncertainties in Hg loadings determined with the Tekran® method are within ±[1 % + 1.2 pg] and ±[6 % + 0.21 pg], respectively. I demonstrate that the Tekran® method can produce significant low biases (≥ 5 %) not only at low Hg sample loadings (< 5 pg) but also at tropospheric background concentrations of gaseous elemental mercury (GEM) and total mercury (THg) (˜ 1 to 2 ng m-3) under typical operating conditions (sample loadings of 5-10 pg). Signal processing uncertainties associated with the Tekran® method can therefore represent a significant unaccounted for addition to the overall ˜ 10 to 15 % uncertainty previously estimated for Tekran®-based GEM and THg measurements. Signal processing bias can also add significantly to uncertainties in Tekran®-based gaseous oxidized mercury (GOM) and particle-bound mercury (PBM) measurements, which often derive from Hg sample loadings < 5 pg. In comparison, estimated signal processing uncertainties associated with the new methods described herein are low, ranging from within ±0.053 pg, when the Hg thermal desorption peaks are defined manually, to within ±[2 % + 0.080 pg] when peak definition is automated. Mercury limits of detection (LODs

Graphene Thermal Properties: Applications in Thermal Management and Energy Storage

Directory of Open Access Journals (Sweden)

Jackie D. Renteria

2014-11-01

Full Text Available We review the thermal properties of graphene, few-layer graphene and graphene nanoribbons, and discuss practical applications of graphene in thermal management and energy storage. The first part of the review describes the state-of-the-art in the graphene thermal field focusing on recently reported experimental and theoretical data for heat conduction in graphene and graphene nanoribbons. The effects of the sample size, shape, quality, strain distribution, isotope composition, and point-defect concentration are included in the summary. The second part of the review outlines thermal properties of graphene-enhanced phase change materials used in energy storage. It is shown that the use of liquid-phase-exfoliated graphene as filler material in phase change materials is promising for thermal management of high-power-density battery parks. The reported experimental and modeling results indicate that graphene has the potential to outperform metal nanoparticles, carbon nanotubes, and other carbon allotropes as filler in thermal management materials.

Constraining Non-thermal and Thermal properties of Dark Matter

Directory of Open Access Journals (Sweden)

Bhupal eDev

2014-05-01

Full Text Available We describe the evolution of Dark Matter (DM abundance from the very onset of its creation from inflaton decay under the assumption of an instantaneous reheating. Based on the initial conditions such as the inflaton mass and its decay branching ratio to the DM species, the reheating temperature, and the mass and interaction rate of the DM with the thermal bath, the DM particles can either thermalize (fully/partially with the primordial bath or remain non-thermal throughout their evolution history. In the thermal case, the final abundance is set by the standard freeze-out mechanism for large annihilation rates, irrespective of the initial conditions. For smaller annihilation rates, it can be set by the freeze-in mechanism which also does not depend on the initial abundance, provided it is small to begin with. For even smaller interaction rates, the DM decouples while being non-thermal, and the relic abundance will be essentially set by the initial conditions. We put model-independent constraints on the DM mass and annihilation rate from over-abundance by exactly solving the relevant Boltzmann equations, and identify the thermal freeze-out, freeze-in and non-thermal regions of the allowed parameter space. We highlight a generic fact that inflaton decay to DM inevitably leads to an overclosure of the Universe for a large range of DM parameter space, and thus poses a stringent constraint that must be taken into account while constructing models of DM. For the thermal DM region, we also show the complementary constraints from indirect DM search experiments, Big Bang Nucleosynthesis, Cosmic Microwave Background, Planck measurements, and theoretical limits due to the unitarity of S-matrix. For the non-thermal DM scenario, we show the allowed parameter space in terms of the inflaton and DM masses for a given reheating temperature, and compute the comoving free-streaming length to identify the hot, warm and cold DM regimes.

Eutectic mixtures of some fatty acids for latent heat storage: Thermal properties and thermal reliability with respect to thermal cycling

International Nuclear Information System (INIS)

Sari, Ahmet

2006-01-01

Accelerated thermal cycle tests have been conducted to study the change in melting temperatures and latent heats of fusion of the eutectic mixtures of lauric acid (LA)-myristic acid (MA), lauric acid (LA)-palmitic acid (PA) and myristic acid (MA)-stearic acid (SA) as latent heat storage materials. The thermal properties of these materials were determined by the differential scanning calorimetry (DSC) analysis method. The thermal reliability of the eutectic mixtures after melt/freeze cycles of 720, 1080 and 1460 was also evaluated using the DSC curves. The accelerated thermal cycle tests indicate that the melting temperatures usually tend to decrease, and the variations in the latent heats of fusion are irregular with increasing number of thermal cycles. Moreover, the probable reasons for the change in thermal properties of the eutectic mixtures after repeated thermal cycles were investigated. Fourier Transform Infrared (FT-IR) spectroscopic analysis indicates that the accelerated melt/freeze processes do not cause any degradation in the chemical structure of the mixtures. The change in thermal properties of the eutectic mixtures with increasing number of thermal cycles is only because of the presence of certain amounts of impurities in the fatty acids used in their preparation. It is concluded that the tested eutectic mixtures have reasonable thermal properties and thermal reliability as phase change materials (PCMs) for latent heat storage in any solar heating applications that include a four year utilization period

Thermal neutron moderating device

International Nuclear Information System (INIS)

Takigami, Hiroyuki.

1995-01-01

In a thermal neutron moderating device, superconductive coils for generating magnetic fields capable of applying magnetic fields vertical to the longitudinal direction of a thermal neutron passing tube, and superconductive coils for magnetic field gradient for causing magnetic field gradient in the longitudinal direction of the thermal neutron passing tube are disposed being stacked at the outside of the thermal neutron passing tube. When magnetic field gradient is present vertically to the direction of a magnetic moment, thermal neutrons undergo forces in the direction of the magnetic field gradient in proportion to the magnetic moment. Then, the magnetic moment of the thermal neutrons is aligned with the direction vertical to the passing direction of the thermal neutrons, to cause the magnetic field gradient in the passing direction of the thermal neutrons. The speed of the thermal neutrons can be optionally selected and the wavelength can freely be changed by applying forces to the thermal neutrons and changing the extent and direction of the magnetic field gradient. Superconductive coils are used as the coils for generating magnetic fields and the magnetic field gradient in order to change extremely high energy of the thermal neutrons. (N.H.)

Atmospheric influences on infrared-laser signals used for occultation measurements between Low Earth Orbit satellites

Directory of Open Access Journals (Sweden)

S. Schweitzer

2011-10-01

Full Text Available LEO-LEO infrared-laser occultation (LIO is a new occultation technique between Low Earth Orbit (LEO satellites, which applies signals in the short wave infrared spectral range (SWIR within 2 μm to 2.5 μm. It is part of the LEO-LEO microwave and infrared-laser occultation (LMIO method that enables to retrieve thermodynamic profiles (pressure, temperature, humidity and altitude levels from microwave signals and profiles of greenhouse gases and further variables such as line-of-sight wind speed from simultaneously measured LIO signals. Due to the novelty of the LMIO method, detailed knowledge of atmospheric influences on LIO signals and of their suitability for accurate trace species retrieval did not yet exist. Here we discuss these influences, assessing effects from refraction, trace species absorption, aerosol extinction and Rayleigh scattering in detail, and addressing clouds, turbulence, wind, scattered solar radiation and terrestrial thermal radiation as well. We show that the influence of refractive defocusing, foreign species absorption, aerosols and turbulence is observable, but can be rendered small to negligible by use of the differential transmission principle with a close frequency spacing of LIO absorption and reference signals within 0.5%. The influences of Rayleigh scattering and terrestrial thermal radiation are found negligible. Cloud-scattered solar radiation can be observable under bright-day conditions, but this influence can be made negligible by a close time spacing (within 5 ms of interleaved laser-pulse and background signals. Cloud extinction loss generally blocks SWIR signals, except very thin or sub-visible cirrus clouds, which can be addressed by retrieving a cloud layering profile and exploiting it in the trace species retrieval. Wind can have a small influence on the trace species absorption, which can be made negligible by using a simultaneously retrieved or a moderately accurate background wind speed profile. We

Non-LTE considerations in spectral diagnostics of thermal transport and implosion experiments

International Nuclear Information System (INIS)

Epstein, R.; Skupsky, S.; Delettrez, J.; Yaakobi, B.

1984-01-01

Recent thermal-transport and target-implosion experiments have used the emission of radiation from highly-ionized ions to signal the advance of laser-driven heat fronts and to mark the trajectories and stagnation points of imploding shells. We examine the results of such experiments with particular attention given to non-LTE effects of non-Maxwellian electrons and of finite ionization times on the populations of signature-emitting atomic species and on the formation of signature spectra and x-ray images in these experiments

Compatibility of a dark matter discovery at XENONnT or LZ with the WIMP thermal production mechanism

Science.gov (United States)

Catena, Riccardo; Conrad, Jan; Krauss, Martin B.

2018-05-01

The discovery of dark matter (DM) at XENONnT or LZ would place constraints on DM particle mass and coupling constants. It is interesting to ask when these constraints can be compatible with the DM thermal production mechanism. We address this question within the most general set of renormalizable models that preserve Lorentz and gauge symmetry, and that extend the standard model by one DM candidate of mass mDM and one particle of mass Mmed mediating DM-quark interactions. Our analysis divides into two parts. First, we postulate that XENONnT/LZ has detected μS˜O (100 ) signal events, and use this input to calculate the DM relic density, ΩDMh2. Then, we identify the regions in the Mmed-ΩDMh2 plane which are compatible with the observed signal and with current CMB data. We find that for most of the models considered here, O (100 ) signal events at XENONnT/LZ and the DM thermal production are only compatible for resonant DM annihilations, i.e. for Mmed≃2 mDM. In this case, XENONnT/LZ would be able to simultaneously measure mDM and Mmed. We also discuss the dependence of our results on mDM, μS and the DM spin, and provide analytic expressions for annihilation cross sections and mediator decay widths for all models considered in this study.

Epidermal photonic devices for quantitative imaging of temperature and thermal transport characteristics of the skin

Science.gov (United States)

Gao, Li; Zhang, Yihui; Malyarchuk, Viktor; Jia, Lin; Jang, Kyung-In; Chad Webb, R.; Fu, Haoran; Shi, Yan; Zhou, Guoyan; Shi, Luke; Shah, Deesha; Huang, Xian; Xu, Baoxing; Yu, Cunjiang; Huang, Yonggang; Rogers, John A.

2014-09-01

Characterization of temperature and thermal transport properties of the skin can yield important information of relevance to both clinical medicine and basic research in skin physiology. Here we introduce an ultrathin, compliant skin-like, or ‘epidermal’, photonic device that combines colorimetric temperature indicators with wireless stretchable electronics for thermal measurements when softly laminated on the skin surface. The sensors exploit thermochromic liquid crystals patterned into large-scale, pixelated arrays on thin elastomeric substrates; the electronics provide means for controlled, local heating by radio frequency signals. Algorithms for extracting patterns of colour recorded from these devices with a digital camera and computational tools for relating the results to underlying thermal processes near the skin surface lend quantitative value to the resulting data. Application examples include non-invasive spatial mapping of skin temperature with milli-Kelvin precision (±50 mK) and sub-millimetre spatial resolution. Demonstrations in reactive hyperaemia assessments of blood flow and hydration analysis establish relevance to cardiovascular health and skin care, respectively.

Signaling aggression.

Science.gov (United States)

van Staaden, Moira J; Searcy, William A; Hanlon, Roger T

2011-01-01

From psychological and sociological standpoints, aggression is regarded as intentional behavior aimed at inflicting pain and manifested by hostility and attacking behaviors. In contrast, biologists define aggression as behavior associated with attack or escalation toward attack, omitting any stipulation about intentions and goals. Certain animal signals are strongly associated with escalation toward attack and have the same function as physical attack in intimidating opponents and winning contests, and ethologists therefore consider them an integral part of aggressive behavior. Aggressive signals have been molded by evolution to make them ever more effective in mediating interactions between the contestants. Early theoretical analyses of aggressive signaling suggested that signals could never be honest about fighting ability or aggressive intentions because weak individuals would exaggerate such signals whenever they were effective in influencing the behavior of opponents. More recent game theory models, however, demonstrate that given the right costs and constraints, aggressive signals are both reliable about strength and intentions and effective in influencing contest outcomes. Here, we review the role of signaling in lieu of physical violence, considering threat displays from an ethological perspective as an adaptive outcome of evolutionary selection pressures. Fighting prowess is conveyed by performance signals whose production is constrained by physical ability and thus limited to just some individuals, whereas aggressive intent is encoded in strategic signals that all signalers are able to produce. We illustrate recent advances in the study of aggressive signaling with case studies of charismatic taxa that employ a range of sensory modalities, viz. visual and chemical signaling in cephalopod behavior, and indicators of aggressive intent in the territorial calls of songbirds. Copyright © 2011 Elsevier Inc. All rights reserved.

In-plane thermal conductivity measurements of ZnO-, ZnS-, and YSZ thin-films on glass substrates

Energy Technology Data Exchange (ETDEWEB)

Hartung, David; Gather, Florian; Kronenberger, Achim; Kuhl, Florian; Meyer, Bruno K.; Klar, Peter J. [I. Physikalisches Institut, Justus-Liebig-University, Heinrich-Buff-Ring 16, 35392 Giessen (Germany)

2012-07-01

In this work we present in-plane thermal conductivity measurements of ZnO-, ZnS-, and YSZ thin-films. Borosilicate glass with a thickness of 50 microns and low thermal conductivity for improving the signal to noise ratio was used as substrate material. The above different films are deposited by rf-sputtering and have a thickness of about 1 micron. Our approach is a steady-state measurement. A wide metal wire on the film is used as a heater and two parallel lying narrow wires at distances of 100 microns and 200 microns from the heater wire, respectively, serve as the temperature sensors. The wire structure design is transfered on to the thin films by photolithography and metal evaporation. Measurements of the in-plane thermal conductivities of the above mentioned materials are presented and compared with corresponding results in the literature.

Solar thermal barometer

International Nuclear Information System (INIS)

Anon.

2004-01-01

After the bad year of 2002, the european solar thermal market returned to double-digit growth rate in 2003: 22%. Nevertheless, the sector still has not recovered the growth rate it had in the early 2000 and European Commission targets are still far from being reached. This paper presents the thermal solar industry barometer. Data on the evolution of annually installed surfaces in the european union since 1993, the cumulated capacity of thermal collectors installed in the European Union, the estimation of the annual energy production associated to european solar thermal capacities and the main companies of the European Union thermal solar sector are presented and discussed. (A.L.B.)

Multiple thermal transitions and anisotropic thermal expansions of vertically aligned carbon nanotubes

Science.gov (United States)

Ya'akobovitz, Assaf

2016-10-01

Vertically aligned carbon nanotubes (VA-CNTs) hold the potential to play an instrumental role in a wide variety of applications in micro- and nano-devices and composites. However, their successful large-scale implementation in engineering systems requires a thorough understanding of their material properties, including their thermal behavior, which was the focus of the current study. Thus, the thermal expansion of as-grown VA-CNT microstructures was investigated while increasing the temperature from room temperature to 800 °C and then cooling it down. First thermal transition was observed at 191 ± 68 °C during heating, and an additional thermal transition was observed at 523 ± 138 °C during heating and at similar temperatures during cooling. Each thermal transition was characterized by a significant change in the coefficient of thermal expansion (CTE), which can be related to a morphological change in the VA-CNT microstructures. Measurements of the CTEs in the lateral directions revealed differences in the lateral thermal behaviors of the top, middle, and bottom portions of the VA-CNT microstructures, again indicating that their morphology dominates their thermal characteristics. A hysteretic behavior was observed, as the measured values of CTEs were altered due to the applied thermal loads and the height of the microstructures was slightly higher compared to its initial value. These findings provide an insight into the anisotropic thermal behavior of VA-CNT microstructures and shed light on the relationship between their morphology and thermal behavior.

Robust power detector for wideband signals among many single tone signals

Science.gov (United States)

Musgrove, Cameron H.; Thompson, Douglas

2018-03-06

Various technologies for isolating a signal of interest from signals received contemporaneously by an antenna are described herein. A time period for which a signal of interest is present in a second signal can be identified based upon ratios of values of the second signal to the mean value of the second signal. When the ratio of the value of the second signal at a particular time to the mean of the second signal exceeds a threshold value, the signal of interest is considered to be present in the second signal.

Rapid, non-destructive and non-contact inspection of solid foods by means of photothermal radiometry; thermal effusivity and initial heating coefficient

Science.gov (United States)

Gijsbertsen, A.; Bicanic, D.; Gielen, J. L. W.; Chirtoc, M.

2004-03-01

CO 2-laser photothermal radiometry (PTR) was demonstrated to be suitable for the non-destructive and non-contact characterization (both optical and thermal) of solid phase agricultural commodities (fresh vegetables, fruits) and confectionery products (candy). Proper interpretation of PTR signals enable one to calculate two parameters, i.e. the well known thermal effusivity e ( e= λρc p, where λ and ρcp are the thermal conductivity and the volume specific heat, respectively) and a newly introduced physical quantity termed 'initial heating coefficient' chi ( χ= β/( ρcp), β is the absorption coefficient). Obtained values for e are in a good agreement with data reported in the literature. PTR enables one to rapidly determine e via a single measurement. As opposed to this, the knowledge of two out of three thermophysical parameters (thermal diffusivity, thermal conductivity and volume specific heat) is a condition sine qua non for determining effusivity in the conventional manner.

Estimating thermal diffusivity and specific heat from needle probe thermal conductivity data

Science.gov (United States)

Waite, W.F.; Gilbert, L.Y.; Winters, W.J.; Mason, D.H.

2006-01-01

Thermal diffusivity and specific heat can be estimated from thermal conductivity measurements made using a standard needle probe and a suitably high data acquisition rate. Thermal properties are calculated from the measured temperature change in a sample subjected to heating by a needle probe. Accurate thermal conductivity measurements are obtained from a linear fit to many tens or hundreds of temperature change data points. In contrast, thermal diffusivity calculations require a nonlinear fit to the measured temperature change occurring in the first few tenths of a second of the measurement, resulting in a lower accuracy than that obtained for thermal conductivity. Specific heat is calculated from the ratio of thermal conductivity to diffusivity, and thus can have an uncertainty no better than that of the diffusivity estimate. Our thermal conductivity measurements of ice Ih and of tetrahydrofuran (THF) hydrate, made using a 1.6 mm outer diameter needle probe and a data acquisition rate of 18.2 pointss, agree with published results. Our thermal diffusivity and specific heat results reproduce published results within 25% for ice Ih and 3% for THF hydrate. ?? 2006 American Institute of Physics.

Salicylic acid signaling inhibits apoplastic reactive oxygen species signaling.

Science.gov (United States)

Xu, Enjun; Brosché, Mikael

2014-06-04

Reactive oxygen species (ROS) are used by plants as signaling molecules during stress and development. Given the amount of possible challenges a plant face from their environment, plants need to activate and prioritize between potentially conflicting defense signaling pathways. Until recently, most studies on signal interactions have focused on phytohormone interaction, such as the antagonistic relationship between salicylic acid (SA)-jasmonic acid and cytokinin-auxin. In this study, we report an antagonistic interaction between SA signaling and apoplastic ROS signaling. Treatment with ozone (O3) leads to a ROS burst in the apoplast and induces extensive changes in gene expression and elevation of defense hormones. However, Arabidopsis thaliana dnd1 (defense no death1) exhibited an attenuated response to O3. In addition, the dnd1 mutant displayed constitutive expression of defense genes and spontaneous cell death. To determine the exact process which blocks the apoplastic ROS signaling, double and triple mutants involved in various signaling pathway were generated in dnd1 background. Simultaneous elimination of SA-dependent and SA-independent signaling components from dnd1 restored its responsiveness to O3. Conversely, pre-treatment of plants with SA or using mutants that constitutively activate SA signaling led to an attenuation of changes in gene expression elicited by O3. Based upon these findings, we conclude that plants are able to prioritize the response between ROS and SA via an antagonistic action of SA and SA signaling on apoplastic ROS signaling.

Thermal Transport in Diamond Films for Electronics Thermal Management

Science.gov (United States)

2018-03-01

AFRL-RY-WP-TR-2017-0219 THERMAL TRANSPORT IN DIAMOND FILMS FOR ELECTRONICS THERMAL MANAGEMENT Samuel Graham Georgia Institute of Technology MARCH... ELECTRONICS THERMAL MANAGEMENT 5a. CONTRACT NUMBER FA8650-15-C-7517 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 61101E 6. AUTHOR(S) Samuel...seeded sample (NRL 010516, Die A5). The NCD membrane and Al layer thicknesses, tNCD, were measured via transmission electron microscopy (TEM). The

Measurement of optically and thermally stimulated electron emission from natural minerals

DEFF Research Database (Denmark)

Ankjærgaard, C.; Murray, A.S.; Denby, P.M.

2006-01-01

to a Riso TL/OSL reader, enabling optically stimulated electrons (OSE) and thermally stimulated electrons (TSE) to be measured simultaneously with optically stimulated luminescence (OSL) and thermoluminescence (TL). Repeated irradiation and measurement is possible without removing the sample from...... the counting chamber. Using this equipment both OSE and TSE from loose sand-sized grains of natural minerals has been recorded. It is shown that both the surface electron traps (giving rise to the OSE signals) and the bulk traps (giving rise to OSL) have the same dosimetric properties. A comparison of OSL...

Thermal neutrons thermoluminescence dosimetry using CaF2 + KBr e CaSO4: Dy + Br

International Nuclear Information System (INIS)

Leite, A.M.P.

1979-01-01

Cold-pressed samples of CaF 2 + KBr and CaSO 4 :Dy + KBr have been used in the thermal neutron detection by the thermoluminescence technique. The amount of 100 mg of the TL phosphor added to 80 mg of KBr showed to be the optimum mixture regarding sensitivity as well as the handling of the dosimeters. The detection is based on the self-irradiation of the phosphor by the Br isotopes activated by exposure to a neutron-gama field. The prompt dose and consequentely the gama contribution are erased by post-irradiation thermal annealing. A linear dependence has been found between the TL self-induced signal and the thermal neutron flux in the range 10 6 n.cm -2 .seg -1 -10 -12 n.cm -2 .seg -1 . The minimum detectable fluence has benn determined as 10 9 n.cm -2 and 10 6 n.cm -2 using pellets of CaF 2 + KBr and CaSO 4 :Dy + KBr, respectively. The main results suggest the use of CaSO 4 :Dy + KBr pellets and TL as a complementary technique for thermal neutron detection. (author) [pt

Thermal Lens Spectroscopy as a 'new' analytical tool for actinide determination in nuclear reprocessing processes

International Nuclear Information System (INIS)

Canto, Fabrice; Couston, Laurent; Magnaldo, Alastair; Broquin, Jean-Emmanuel; Signoret, Philippe

2008-01-01

Thermal Lens Spectroscopy (TLS) consists of measuring the effects induced by the relaxation of molecules excited by photons. Twenty years ago, the Cea already worked on TLS. Technologic reasons impeded. But, needs in sensitive analytical methods coupled with very low sample volumes (for example, traces of Np in the COEX TM process) and also the reduction of the nuclear wastes encourage us to revisit this method thanks to the improvement of optoelectronic technologies. We can also imagine coupling TLS with micro-fluidic technologies, decreasing significantly the experiments cost. Generally two laser beams are used for TLS: one for the selective excitation by molecular absorption (inducing the thermal lens) and one for probing the thermal lens. They can be coupled with different geometries, collinear or perpendicular, depending on the application and on the laser mode. Also, many possibilities of measurement have been studied to detect the thermal lens signal: interferometry, direct intensities variations, deflection etc... In this paper, one geometrical configuration and two measurements have been theoretically evaluated. For a single photodiode detection (z-scan) the limit of detection is calculated to be near 5*10 -6 mol*L -1 for Np(IV) in dodecane. (authors)

Thermal conductivity issues of EB-PVD thermal barrier coatings

Energy Technology Data Exchange (ETDEWEB)

Schulz, U.; Raetzer-Scheibe, H.J.; Saruhan, B. [DLR - German Aerospace Center, Institute of Materials Research, 51170 Cologne (Germany); Renteria, A.F. [BTU, Physical Metallurgy and Materials Technology, Cottbus (Germany)

2007-09-15

The thermal conductivity of electron-beam physical vapor deposited (EB-PVD) thermal barrier coatings (TBCs) was investigated by the Laser Flash technique. Sample type and methodology of data analyses as well as atmosphere during the measurement have some influence on the data. A large variation of the thermal conductivity was found by changes in TBC microstructure. Exposure at high temperature caused sintering of the porous microstructure that finally increased thermal conductivity up to 30 %. EB-PVD TBCs show a distinct thickness dependence of the thermal conductivity due to the anisotropic microstructure in thickness direction. Thin TBCs had a 20 % lower thermal conductivity than thick coatings. New compositions of the ceramic top layer offer the largest potential to lower thermal conductivity. Values down to 0.8W/(mK) have been already demonstrated with virgin coatings of pyrochlore compositions. (Abstract Copyright [2007], Wiley Periodicals, Inc.) [German] Die Waermeleitfaehigkeit von elektronenstrahl-aufgedampften (EB-PVD) Waermedaemmschichten (TBCs) wurde mittels Laser-Flash untersucht. Probentyp, Messmethodik und die Atmosphaere waehrend der Messung haben einen Einfluss auf die Ergebnisse. Aenderungen in der Mikrostruktur der TBC fuehrten zu grossen Unterschieden der Waermeleitfaehigkeit. Eine Hochtemperaturbelastung verursachte Sintervorgaenge in der poroesen Mikrostruktur, was die Waermeleitfaehigkeit um bis zu 30 % ansteigen liess. EB-PVD TBCs zeigen eine deutliche Dickenabhaengigkeit der Waermeleitfaehigkeit durch die Anisotropie der Mikrostruktur in dieser Richtung. Duenne TBCs haben eine um 20 % geringere Waermeleitfaehigkeit als dicke Schichten. Neue Zusammensetzungen der keramischen Deckschicht bieten die groessten Moeglichkeiten fuer eine Reduktion der Waermeleitfaehigkeit. Werte bis zu 0,8 W/(mK) wurden damit bereits erreicht. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

Thermal fatigue. Fluid-structure interaction at thermal mixing events

International Nuclear Information System (INIS)

Schuler, X.; Herter, K.H.; Moogk, S.; Laurien, E.; Kloeren, D.; Kulenovic, R.; Kuschewski, M.

2012-01-01

In the framework of the network research project ''Thermal Fatigue - Basics of the system-, outflow- and material-characteristics of piping under thermal fatigue'' funded by the German Federal Ministry of Education and Research (BMBF) fundamental numerical and experimental investigations on the material behaviour under transient thermal-mechanical stress conditions (high cycle fatigue - HCF) are carried out. The project's background and its network of scientific working groups with their individual working tasks are briefly introduced. The main focus is especially on the joint research tasks within the sub-projects of MPA and IKE which are dealing with thermal mixing of flows in a T-junction configuration and the fluidstructure- interactions (FSI). Therefore, experiments were performed with the newly established FSI test facility at MPA which enables single-phase flow experiments of water in typical power plant piping diameters (DN40 and DN80) at high pressure (maximum 75 bar) and temperatures (maximum 280 C). The experimental results serve as validation data base for numerical modelling of thermal flow mixing by means of thermo-fluid dynamics simulations applying CFD techniques and carried out by IKE as well as for modelling of thermal and mechanical loads of the piping structure by structural mechanics simulations with FEM methods which are executed by MPA. The FSI test facility will be described inclusively the applied measurement techniques, e. g. in particular the novel near-wall LED-induced Fluorescence method for non-intrusive flow temperature measurements. First experimental data and numerical results from CFD and FEM simulations of the thermal mixing of flows in the T-junction are presented.

Nanoscale thermal transport

Science.gov (United States)

Cahill, David G.; Ford, Wayne K.; Goodson, Kenneth E.; Mahan, Gerald D.; Majumdar, Arun; Maris, Humphrey J.; Merlin, Roberto; Phillpot, Simon R.

2003-01-01

Rapid progress in the synthesis and processing of materials with structure on nanometer length scales has created a demand for greater scientific understanding of thermal transport in nanoscale devices, individual nanostructures, and nanostructured materials. This review emphasizes developments in experiment, theory, and computation that have occurred in the past ten years and summarizes the present status of the field. Interfaces between materials become increasingly important on small length scales. The thermal conductance of many solid-solid interfaces have been studied experimentally but the range of observed interface properties is much smaller than predicted by simple theory. Classical molecular dynamics simulations are emerging as a powerful tool for calculations of thermal conductance and phonon scattering, and may provide for a lively interplay of experiment and theory in the near term. Fundamental issues remain concerning the correct definitions of temperature in nonequilibrium nanoscale systems. Modern Si microelectronics are now firmly in the nanoscale regime—experiments have demonstrated that the close proximity of interfaces and the extremely small volume of heat dissipation strongly modifies thermal transport, thereby aggravating problems of thermal management. Microelectronic devices are too large to yield to atomic-level simulation in the foreseeable future and, therefore, calculations of thermal transport must rely on solutions of the Boltzmann transport equation; microscopic phonon scattering rates needed for predictive models are, even for Si, poorly known. Low-dimensional nanostructures, such as carbon nanotubes, are predicted to have novel transport properties; the first quantitative experiments of the thermal conductivity of nanotubes have recently been achieved using microfabricated measurement systems. Nanoscale porosity decreases the permittivity of amorphous dielectrics but porosity also strongly decreases the thermal conductivity. The

Low-temperature thermal expansion

International Nuclear Information System (INIS)

Collings, E.W.

1986-01-01

This chapter discusses the thermal expansion of insulators and metals. Harmonicity and anharmonicity in thermal expansion are examined. The electronic, magnetic, an other contributions to low temperature thermal expansion are analyzed. The thermodynamics of the Debye isotropic continuum, the lattice-dynamical approach, and the thermal expansion of metals are discussed. Relative linear expansion at low temperatures is reviewed and further calculations of the electronic thermal expansion coefficient are given. Thermal expansions are given for Cu, Al and Ti. Phenomenologic thermodynamic relationships are also discussed

Luminescent nanoprobes for thermal bio-sensing: Towards controlled photo-thermal therapies

Energy Technology Data Exchange (ETDEWEB)

Jaque, Daniel, E-mail: daniel.jaque@uam.es [Fluorescence Imaging Group, Departamento de Fisica de Materiales, Universidad Autonoma de Madrid, Madrid 28049 (Spain); Grupo de Fotônica e Fluidos Complexos (GFFC), Instituto de Física, Universidade Federal de Alagoas, 57072-900 Maceió-AL (Brazil); Jacinto, Carlos [Grupo de Fotônica e Fluidos Complexos (GFFC), Instituto de Física, Universidade Federal de Alagoas, 57072-900 Maceió-AL (Brazil)

2016-01-15

Photo-thermal therapies, based on the light-induced local heating of cancer tumors and tissues, are nowadays attracting an increasing attention due to their effectiveness, universality, and low cost. In order to avoid undesirable collateral damage in the healthy tissues surrounding the tumors, photo-thermal therapies should be achieved while monitoring tumor’s temperature in such a way that thermal therapy could be stopped before reaching the damage limit. Measuring tumor temperature is not an easy task at all and novel strategies should be adopted. In this work it is demonstrated how luminescent nanoparticles, in particular Neodymium doped LaF{sub 3} nanoparticles, could be used as multi-functional agents capable of simultaneous heating and thermal sensing. Advantages and disadvantages of such nanoparticles are discussed and the future perspectives are briefly raised. - Highlights: • Thermal control is essential in novel photo-thermal therapies. • Thermal control and heating can be achieved by Neodymium doped nanoparticles. • Perspectives of Neodymium doped nanoparticles in potential in vivo applications are discussed.

Josephson Thermal Memory

Science.gov (United States)

Guarcello, Claudio; Solinas, Paolo; Braggio, Alessandro; Di Ventra, Massimiliano; Giazotto, Francesco

2018-01-01

We propose a superconducting thermal memory device that exploits the thermal hysteresis in a flux-controlled temperature-biased superconducting quantum-interference device (SQUID). This system reveals a flux-controllable temperature bistability, which can be used to define two well-distinguishable thermal logic states. We discuss a suitable writing-reading procedure for these memory states. The time of the memory writing operation is expected to be on the order of approximately 0.2 ns for a Nb-based SQUID in thermal contact with a phonon bath at 4.2 K. We suggest a noninvasive readout scheme for the memory states based on the measurement of the effective resonance frequency of a tank circuit inductively coupled to the SQUID. The proposed device paves the way for a practical implementation of thermal logic and computation. The advantage of this proposal is that it represents also an example of harvesting thermal energy in superconducting circuits.

Thermal energy storage apparatus, controllers and thermal energy storage control methods

Science.gov (United States)

Hammerstrom, Donald J.

2016-05-03

Thermal energy storage apparatus, controllers and thermal energy storage control methods are described. According to one aspect, a thermal energy storage apparatus controller includes processing circuitry configured to access first information which is indicative of surpluses and deficiencies of electrical energy upon an electrical power system at a plurality of moments in time, access second information which is indicative of temperature of a thermal energy storage medium at a plurality of moments in time, and use the first and second information to control an amount of electrical energy which is utilized by a heating element to heat the thermal energy storage medium at a plurality of moments in time.

Negative thermal expansion materials: technological key for control of thermal expansion

OpenAIRE

Koshi Takenaka

2012-01-01

Most materials expand upon heating. However, although rare, some materials contract upon heating. Such negative thermal expansion (NTE) materials have enormous industrial merit because they can control the thermal expansion of materials. Recent progress in materials research enables us to obtain materials exhibiting negative coefficients of linear thermal expansion over −30 ppm K−1. Such giant NTE is opening a new phase of control of thermal expansion in composites. Specifically examining pra...

Improving Thermal and Electrical Efficiency in Photovoltaic Thermal Systems for Sustainable Cooling System Integration

Directory of Open Access Journals (Sweden)

Mohammad Alobaid

2018-06-01

Full Text Available Research into photovoltaic thermal systems is important in solar technologies as photovoltaic thermal systems are designed to produce both electrical and thermal energy, this can lead to improved performance of the overall system. The performance of photovoltaic thermal systems is based on several factors that include photovoltaic thermal materials, design, ambient temperature, inlet and outlet fluid temperature and photovoltaic cell temperature. The aim of this study is to investigate the effect of photovoltaic thermal outlet water temperatures and solar cell temperature on both electrical and thermal efficiency for different range of inlet water temperature. To achieve this, a mathematical model of a photovoltaic thermal system was developed to calculate the anticipated system performance. The factors that affect the efficiency of photovoltaic thermal collectors were discussed and the outlet fluid temperature from the photovoltaic thermal is investigated in order to reach the highest overall efficiency for the solar cooling system. An average thermal and electrical efficiency of 65% and 13.7%, respectively, was achieved and the photovoltaic thermal mathematical model was validated with experimental data from literature.

The Borexino Thermal Monitoring & Management System and simulations of the fluid-dynamics of the Borexino detector under asymmetrical, changing boundary conditions

Science.gov (United States)

Bravo-Berguño, D.; Mereu, R.; Cavalcante, P.; Carlini, M.; Ianni, A.; Goretti, A.; Gabriele, F.; Wright, T.; Yokley, Z.; Vogelaar, R. B.; Calaprice, F.; Inzoli, F.

2018-03-01

A comprehensive monitoring system for the thermal environment inside the Borexino neutrino detector was developed and installed in order to reduce uncertainties in determining temperatures throughout the detector. A complementary thermal management system limits undesirable thermal couplings between the environment and Borexino's active sections. This strategy is bringing improved radioactive background conditions to the region of interest for the physics signal thanks to reduced fluid mixing induced in the liquid scintillator. Although fluid-dynamical equilibrium has not yet been fully reached, and thermal fine-tuning is possible, the system has proven extremely effective at stabilizing the detector's thermal conditions while offering precise insights into its mechanisms of internal thermal transport. Furthermore, a Computational Fluid-Dynamics analysis has been performed, based on the empirical measurements provided by the thermal monitoring system, and providing information into present and future thermal trends. A two-dimensional modeling approach was implemented in order to achieve a proper understanding of the thermal and fluid-dynamics in Borexino. It was optimized for different regions and periods of interest, focusing on the most critical effects that were identified as influencing background concentrations. Literature experimental case studies were reproduced to benchmark the method and settings, and a Borexino-specific benchmark was implemented in order to validate the modeling approach for thermal transport. Finally, fully-convective models were applied to understand general and specific fluid motions impacting the detector's Active Volume.

Temperature Distribution and Thermal Performance of an Aquifer Thermal Energy Storage System

Science.gov (United States)

Ganguly, Sayantan

2017-04-01

Energy conservation and storage has become very crucial to make use of excess energy during times of future demand. Excess thermal energy can be captured and stored in aquifers and this technique is termed as Aquifer Thermal Energy Storage (ATES). Storing seasonal thermal energy in water by injecting it into subsurface and extracting in time of demand is the principle of an ATES system. Using ATES systems leads to energy savings, reduces the dependency on fossil fuels and thus leads to reduction in greenhouse gas emission. This study numerically models an ATES system to store seasonal thermal energy and evaluates the performance of it. A 3D thermo-hydrogeological numerical model for a confined ATES system is presented in this study. The model includes heat transport processes of advection, conduction and heat loss to confining rock media. The model also takes into account regional groundwater flow in the aquifer, geothermal gradient and anisotropy in the aquifer. Results show that thermal injection into the aquifer results in the generation of a thermal-front which grows in size with time. Premature thermal-breakthrough causes thermal interference in the system when the thermal-front reaches the production well and consequences in the fall of system performance and hence should be avoided. This study models the transient temperature distribution in the aquifer for different flow and geological conditions. This may be effectively used in designing an efficient ATES project by ensuring safety from thermal-breakthrough while catering to the energy demand. Based on the model results a safe well spacing is proposed. The thermal energy discharged by the system is determined and strategy to avoid the premature thermal-breakthrough in critical cases is discussed. The present numerical model is applied to simulate an experimental field study which is found to approximate the field results quite well.

Evaluating local and overall thermal comfort in buildings using thermal manikins

Energy Technology Data Exchange (ETDEWEB)

Foda, E.

2012-07-01

Evaluation methods of human thermal comfort that are based on whole-body heat balance with its surroundings may not be adequate for evaluations in non-uniform thermal conditions. Under these conditions, the human body's segments may experience a wide range of room physical parameters and the evaluation of the local (segmental) thermal comfort becomes necessary. In this work, subjective measurements of skin temperature were carried out to investigate the human body's local responses due to a step change in the room temperature; and the variability in the body's local temperatures under different indoor conditions and exposures as well as the physiological steady state local temperatures. Then, a multi-segmental model of human thermoregulation was developed based on these findings to predict the local skin temperatures of individuals' body segments with a good accuracy. The model predictability of skin temperature was verified for steady state and dynamic conditions using measured data at uniform neutral, cold and warm as well as different asymmetric thermal conditions. The model showed very good predictability with average absolute deviation ranged from 0.3-0.8 K. The model was then implemented onto the control system of the thermal manikin 'THERMINATOR' to adjust the segmental skin temperature set-points based on the indoor conditions. This new control for the manikin was experimentally validated for the prediction of local and overall thermal comfort using the equivalent temperature measure. THERMINATOR with the new control mode was then employed in the evaluation of localized floor-heating system variants towards maximum energy efficiency. This aimed at illustrating a design strategy using the thermal manikin to find the optimum geometry and surface area of a floor-heater for a single seated person. Furthermore, a psychological comfort model that is based on local skin temperature was adapted for the use with the model of human

Cysteine residue is not essential for CPM protein thermal-stability assay.

Science.gov (United States)

Wang, Zhaoshuai; Ye, Cui; Zhang, Xinyi; Wei, Yinan

2015-05-01

A popular thermal-stability assay developed especially for the study of membrane proteins uses a thiol-specific probe, 7-diethylamino-3-(4-maleimidophenyl)-4-methylcoumarin (CPM). The fluorescence emission of CPM surges when it forms a covalent bond with the side chain of a free Cys, which becomes more readily accessible upon protein thermal denaturation. Interestingly, the melting temperatures of membrane proteins determined using the CPM assay in literature are closely clustered in the temperature range 45-55 °C. A thorough understanding of the mechanism behind the observed signal change is critical for the accurate interpretation of the protein unfolding. Here we used two α-helical membrane proteins, AqpZ and AcrB, as model systems to investigate the nature of the fluorescence surge in the CPM assay. We found that the transition temperatures measured using circular-dichroism (CD) spectroscopy and the CPM assay were significantly different. To eliminate potential artifact that might arise from the presence of detergent, we monitored the unfolding of two soluble proteins. We found that, contrary to current understanding, the presence of a sulfhydryl group was not a prerequisite for the CPM thermal-stability assay. The observed fluorescence increase is probably caused by binding of the fluorophore to hydrophobic patches exposed upon protein unfolding.

Fossilization processes in siliceous thermal springs: trends in preservation along thermal gradients

Science.gov (United States)

Cady, S. L.; Farmer, J. D.

1996-01-01

To enhance our ability to extract palaeobiological and palaeoenvironmental information from ancient thermal spring deposits, we have studied the processes responsible for the development and preservation of stromatolites in modern subaerial thermal spring systems in Yellowstone National Park (USA). We investigated specimens collected from silica-depositing thermal springs along the thermal gradient using petrographic techniques and scanning electron microscopy. Although it is known that thermophilic cyanobacteria control the morphogenesis of thermal spring stromatolites below 73 degrees C, we have found that biofilms which contain filamentous thermophiles contribute to the microstructural development of subaerial geyserites that occur along the inner rims of thermal spring pools and geyser effluents. Biofilms intermittently colonize the surfaces of subaerial geyserites and provide a favoured substrate for opaline silica precipitation. We have also found that the preservation of biotically produced microfabrics of thermal spring sinters reflects dynamic balances between rates of population growth, decomposition of organic matter, silica deposition and early diagenesis. Major trends in preservation of thermophilic organisms along the thermal gradient are defined by differences in the mode of fossilization, including replacement, encrustation and permineralization.

Photovoltaic. Solar thermal. Solar thermal electricity

International Nuclear Information System (INIS)

2009-01-01

The year 2008 was excellent for solar energy in the European Union. The growth of the installed capacity for photovoltaic was +159% (it means +4747.018 MW) to reach 9689.952 MW and that for solar thermal was +51.5% (it means +3172.5 MW) to reach 19982.7 MW. Worldwide concentrated solar thermal capacity stood at 679 MW in 2009, while this figure may seem low, the sector has a promising future ahead of it. (A.C.)

Overview of thermal conductivity models of anisotropic thermal insulation materials

Science.gov (United States)

Skurikhin, A. V.; Kostanovsky, A. V.

2017-11-01

Currently, the most of existing materials and substances under elaboration are anisotropic. It makes certain difficulties in the study of heat transfer process. Thermal conductivity of the materials can be characterized by tensor of the second order. Also, the parallelism between the temperature gradient vector and the density of heat flow vector is violated in anisotropic thermal insulation materials (TIM). One of the most famous TIM is a family of integrated thermal insulation refractory material («ITIRM»). The main component ensuring its properties is the «inflated» vermiculite. Natural mineral vermiculite is ground into powder state, fired by gas burner for dehydration, and its precipitate is then compressed. The key feature of thus treated batch of vermiculite is a package structure. The properties of the material lead to a slow heating of manufactured products due to low absorption and high radiation reflection. The maximum of reflection function is referred to infrared spectral region. A review of current models of heat propagation in anisotropic thermal insulation materials is carried out, as well as analysis of their thermal and optical properties. A theoretical model, which allows to determine the heat conductivity «ITIRM», can be useful in the study of thermal characteristics such as specific heat capacity, temperature conductivity, and others. Materials as «ITIRM» can be used in the metallurgy industry, thermal energy and nuclear power-engineering.

A novel technique to monitor thermal discharges using thermal infrared imaging.

Science.gov (United States)

Muthulakshmi, A L; Natesan, Usha; Ferrer, Vincent A; Deepthi, K; Venugopalan, V P; Narasimhan, S V

2013-09-01

Coastal temperature is an important indicator of water quality, particularly in regions where delicate ecosystems sensitive to water temperature are present. Remote sensing methods are highly reliable for assessing the thermal dispersion. The plume dispersion from the thermal outfall of the nuclear power plant at Kalpakkam, on the southeast coast of India, was investigated from March to December 2011 using thermal infrared images along with field measurements. The absolute temperature as provided by the thermal infrared (TIR) images is used in the Arc GIS environment for generating a spatial pattern of the plume movement. Good correlation of the temperature measured by the TIR camera with the field data (r(2) = 0.89) make it a reliable method for the thermal monitoring of the power plant effluents. The study portrays that the remote sensing technique provides an effective means of monitoring the thermal distribution pattern in coastal waters.

RADYN Simulations of Non-thermal and Thermal Models of Ellerman Bombs

Energy Technology Data Exchange (ETDEWEB)

Hong, Jie; Ding, M. D. [School of Astronomy and Space Science, Nanjing University, Nanjing 210023 (China); Carlsson, Mats, E-mail: dmd@nju.edu.cn [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, NO-0315 Oslo (Norway)

2017-08-20

Ellerman bombs (EBs) are brightenings in the H α line wings that are believed to be caused by magnetic reconnection in the lower atmosphere. To study the response and evolution of the chromospheric line profiles, we perform radiative hydrodynamic simulations of EBs using both non-thermal and thermal models. Overall, these models can generate line profiles that are similar to observations. However, in non-thermal models we find dimming in the H α line wings and continuum when the heating begins, while for the thermal models dimming occurs only in the H α line core, and with a longer lifetime. This difference in line profiles can be used to determine whether an EB is dominated by non-thermal heating or thermal heating. In our simulations, if a higher heating rate is applied, then the H α line will be unrealistically strong and there are still no clear UV burst signatures.

RADYN Simulations of Non-thermal and Thermal Models of Ellerman Bombs

Science.gov (United States)

Hong, Jie; Carlsson, Mats; Ding, M. D.

2017-08-01

Ellerman bombs (EBs) are brightenings in the Hα line wings that are believed to be caused by magnetic reconnection in the lower atmosphere. To study the response and evolution of the chromospheric line profiles, we perform radiative hydrodynamic simulations of EBs using both non-thermal and thermal models. Overall, these models can generate line profiles that are similar to observations. However, in non-thermal models we find dimming in the Hα line wings and continuum when the heating begins, while for the thermal models dimming occurs only in the Hα line core, and with a longer lifetime. This difference in line profiles can be used to determine whether an EB is dominated by non-thermal heating or thermal heating. In our simulations, if a higher heating rate is applied, then the Hα line will be unrealistically strong and there are still no clear UV burst signatures.

Effects of thermal underwear on thermal and subjective responses in winter.

Science.gov (United States)

Choi, Jeong-Wha; Lee, Joo-Young; Kim, So-Young

2003-01-01

This study was conducted to obtain basic data in improving the health of Koreans, saving energy and protecting environments. This study investigated the effects of wearing thermal underwear for keeping warm in the office in winter where temperature is not as low as affecting work efficiency, on thermoregulatory responses and subjective sensations. In order to create an environment where every subject feels the same thermal sensation, two experimental conditions were selected through preliminary experiments: wearing thermal underwear in 18 degrees C air (18-condition) and not wearing thermal underwear in 23 degrees C air (23-condition). Six healthy male students participated in this study as experiment subjects. Measurement items included rectal temperature (T(re)), skin temperature (T(sk)), clothing microclimate temperature (T(cm)), thermal sensation and thermal comfort. The results are as follows: (1) T(re) of all subjects was maintained constant at 37.1 degrees C under both conditions, indicating no significant differences. (2) (T)(sk) under the 18-condition and the 23-condition were 32.9 degrees C and 33.7 degrees C, respectively, indicating a significant level of difference (pcomfortable under both conditions. It was found (T)(sk) decreased due to a drop in the skin temperature of hands and feet, and the subjects felt cooler wearing only one layer of normal thermal underwear at 18 degrees C. Yet, the thermal comfort level, T(re) and T(cm) of chest part under the 18-condition were the same as those under the 23-condition. These results show that the same level of comfort, T(re) and T(cm) can be maintained as that of an environment about 5 degrees C higher in the office in winter, by wearing one layer of thermal underwear. In this regard, this study suggests that lowering indoor temperature by wearing thermal underwear in winter can contribute to saving energy and improving health.

Design and Development of Embedded System for the Measurement of Thermal Conductivity of Liquids by Transient Hot Wire Method

Directory of Open Access Journals (Sweden)

Nagamani GOSALA

2011-06-01

Full Text Available Thermal conductivity of polymers is an important property for both polymer applications and processing industry. The successful application of thermal insulating fluids in the last several years has demonstrated that such fluids can effectively control the heat loss. Understanding and controlling the thermal environment for oilfield operations has been a concern and research topic. As a consequence of this trend, there is huge demand for new methods of instrumentation to evaluate the performance of material properties and characterization. The main aim of the present study is the development of hardware and software for measuring the thermal conductivity of liquids using transient hot wire method. Because of the relatively short experimental times and large amounts of parametric data involved in the measurement process, embedded control of the measurement is essential. The experimental implementation requires a suitable temperature sensing, automatic control, data acquisition, and data analysis systems accomplished using an embedded system that has been built around the ARM LPC 2103 mixed signal controller.

Microscale solid-state thermal diodes enabling ambient temperature thermal circuits for energy applications

KAUST Repository

Wang, Song

2017-05-10

Thermal diodes, or devices that transport thermal energy asymmetrically, analogous to electrical diodes, hold promise for thermal energy harvesting and conservation, as well as for phononics or information processing. The junction of a phase change material and phase invariant material can form a thermal diode; however, there are limited constituent materials available for a given target temperature, particularly near ambient. In this work, we demonstrate that a micro and nanoporous polystyrene foam can house a paraffin-based phase change material, fused to PMMA, to produce mechanically robust, solid-state thermal diodes capable of ambient operation with Young\\'s moduli larger than 11.5 MPa and 55.2 MPa above and below the melting transition point, respectively. Moreover, the composites show significant changes in thermal conductivity above and below the melting point of the constituent paraffin and rectification that is well-described by our previous theory and the Maxwell–Eucken model. Maximum thermal rectifications range from 1.18 to 1.34. We show that such devices perform reliably enough to operate in thermal diode bridges, dynamic thermal circuits capable of transforming oscillating temperature inputs into single polarity temperature differences – analogous to an electrical diode bridge with widespread implications for transient thermal energy harvesting and conservation. Overall, our approach yields mechanically robust, solid-state thermal diodes capable of engineering design from a mathematical model of phase change and thermal transport, with implications for energy harvesting.

Reduced thermal quenching in indium-rich self-organized InGaN/GaN quantum dots

KAUST Repository

Elafandy, Rami T.

2012-01-01

Differences in optical and structural properties of indium rich (27), indium gallium nitride (InGaN) self-organized quantum dots (QDs), with red wavelength emission, and the two dimensional underlying wetting layer (WL) are investigated. Temperature dependent micro-photoluminescence (?PL) reveals a decrease in thermal quenching of the QDs integrated intensity compared to that of the WL. This difference in behaviour is due to the 3-D localization of carriers within the QDs preventing them from thermalization to nearby traps causing an increase in the internal quantum efficiency of the device. Excitation power dependent ?PL shows a slower increase of the QDs PL signal compared to the WL PL which is believed to be due to the QDs saturation. © 2012 American Institute of Physics.

Non-thermal Plasma Activates Human Keratinocytes by Stimulation of Antioxidant and Phase II Pathways

Science.gov (United States)

Schmidt, Anke; Dietrich, Stephan; Steuer, Anna; Weltmann, Klaus-Dieter; von Woedtke, Thomas; Masur, Kai; Wende, Kristian

2015-01-01

Non-thermal atmospheric pressure plasma provides a novel therapeutic opportunity to control redox-based processes, e.g. wound healing, cancer, and inflammatory diseases. By spatial and time-resolved delivery of reactive oxygen and nitrogen species, it allows stimulation or inhibition of cellular processes in biological systems. Our data show that both gene and protein expression is highly affected by non-thermal plasma. Nuclear factor erythroid-related factor 2 (NRF2) and phase II enzyme pathway components were found to act as key controllers orchestrating the cellular response in keratinocytes. Additionally, glutathione metabolism, which is a marker for NRF2-related signaling events, was affected. Among the most robustly increased genes and proteins, heme oxygenase 1, NADPH-quinone oxidoreductase 1, and growth factors were found. The roles of NRF2 targets, investigated by siRNA silencing, revealed that NRF2 acts as an important switch for sensing oxidative stress events. Moreover, the influence of non-thermal plasma on the NRF2 pathway prepares cells against exogenic noxae and increases their resilience against oxidative species. Via paracrine mechanisms, distant cells benefit from cell-cell communication. The finding that non-thermal plasma triggers hormesis-like processes in keratinocytes facilitates the understanding of plasma-tissue interaction and its clinical application. PMID:25589789

Thermal fatigue. Fluid-structure interaction at thermal mixing events

Energy Technology Data Exchange (ETDEWEB)

Schuler, X.; Herter, K.H.; Moogk, S. [Stuttgart Univ. (Germany). MPA; Laurien, E.; Kloeren, D.; Kulenovic, R.; Kuschewski, M. [Stuttgart Univ. (Germany). Inst. of Nuclear Technology and Energy Systems

2012-07-01

In the framework of the network research project ''Thermal Fatigue - Basics of the system-, outflow- and material-characteristics of piping under thermal fatigue'' funded by the German Federal Ministry of Education and Research (BMBF) fundamental numerical and experimental investigations on the material behaviour under transient thermal-mechanical stress conditions (high cycle fatigue - HCF) are carried out. The project's background and its network of scientific working groups with their individual working tasks are briefly introduced. The main focus is especially on the joint research tasks within the sub-projects of MPA and IKE which are dealing with thermal mixing of flows in a T-junction configuration and the fluidstructure- interactions (FSI). Therefore, experiments were performed with the newly established FSI test facility at MPA which enables single-phase flow experiments of water in typical power plant piping diameters (DN40 and DN80) at high pressure (maximum 75 bar) and temperatures (maximum 280 C). The experimental results serve as validation data base for numerical modelling of thermal flow mixing by means of thermo-fluid dynamics simulations applying CFD techniques and carried out by IKE as well as for modelling of thermal and mechanical loads of the piping structure by structural mechanics simulations with FEM methods which are executed by MPA. The FSI test facility will be described inclusively the applied measurement techniques, e. g. in particular the novel near-wall LED-induced Fluorescence method for non-intrusive flow temperature measurements. First experimental data and numerical results from CFD and FEM simulations of the thermal mixing of flows in the T-junction are presented.

Tunable thermal link

Science.gov (United States)

Chang, Chih-Wei; Majumdar, Arunava; Zettl, Alexander K.

2014-07-15

Disclosed is a device whereby the thermal conductance of a multiwalled nanostructure such as a multiwalled carbon nanotube (MWCNT) can be controllably and reversibly tuned by sliding one or more outer shells with respect to the inner core. As one example, the thermal conductance of an MWCNT dropped to 15% of the original value after extending the length of the MWCNT by 190 nm. The thermal conductivity returned when the tube was contracted. The device may comprise numbers of multiwalled nanotubes or other graphitic layers connected to a heat source and a heat drain and various means for tuning the overall thermal conductance for applications in structure heat management, heat flow in nanoscale or microscale devices and thermal logic devices.

Investigating correlations of local seismicty with anomalous geoelectrical, hydrogeological and geochemical signals jointly recorded in Basilicata Region (Southern Italy

Directory of Open Access Journals (Sweden)

M. Mucciarelli

2007-06-01

Full Text Available This paper presents the preliminary results analysing the correlation between local seismicity and geoelectrical, hydrogeological and geochemical signals concomitantly recorded in Basilicata Region, one of the most seismically active areas in Southern Italy. The signals were recorded by two stations: Tito and Tramutola. Tito station measures vertically the Self-Potential field (SP by an array of five no-polarizable electrodes equally spaced with the common electrode at 20 m depth as well as water-level, water-temperature and electrical-conductivity. Tramutola station measures self-potential signals in soil surface, gas flow and water temperature in a thermal-water well, as well as atmospheric barometric pressure and ambient temperature. Correlations were found between the sharp variability of the signals recorded by both stations and the seismic sequence that occurred on September 3 to 4, 2004, allowing us to link these anomalies with the tectonic evolution of the investigated area.

A thermal ground cloak

International Nuclear Information System (INIS)

Yang, Tianzhi; Wu, Qinghe; Xu, Weikai; Liu, Di; Huang, Lujun; Chen, Fei

2016-01-01

The thermal cloak has been a long-standing scientific dream of researchers and engineers. Recently thermal metamaterials with man-made micro-structure have been presented based on the principle of transformation optics (TO). This new concept has received considerable attention, which is a powerful tool for manipulating heat flux in thermal imaging systems. However, the inherent material singularity has long been a captivation of experimental realization. As an alternative method, the scattering-cancellation-based cloak (or bi-layer thermal cloak) has been presented to remove the singularity for achieving the same cloaking performance. Nevertheless, such strategy needs prerequisite knowledge (geometry and conductivity) of the object to be cloaked. In this paper, a new thermal ground cloak is presented to overcome the limitations. The device is designed, fabricated and measured to verify the thermal cloaking performance. We experimentally show that the remarkably low complexity of the device can fully and effectively be manipulated using realizable transformation thermal devices. More importantly, this thermal ground cloak is designed to exclude heat flux without knowing the information of the cloaked object. - Highlights: • We present the first thermal carpet cloak. • The carpet can thermally cloak any shaped object without knowing the properties of the object to be cloaked. • Excellent agreements between simulation and experiment are observed.

Optimal Signal Quality Index for Photoplethysmogram Signals

Directory of Open Access Journals (Sweden)

Mohamed Elgendi

2016-09-01

Full Text Available A photoplethysmogram (PPG is a noninvasive circulatory signal related to the pulsatile volume of blood in tissue and is typically collected by pulse oximeters. PPG signals collected via mobile devices are prone to artifacts that negatively impact measurement accuracy, which can lead to a significant number of misleading diagnoses. Given the rapidly increased use of mobile devices to collect PPG signals, developing an optimal signal quality index (SQI is essential to classify the signal quality from these devices. Eight SQIs were developed and tested based on: perfusion, kurtosis, skewness, relative power, non-stationarity, zero crossing, entropy, and the matching of systolic wave detectors. Two independent annotators annotated all PPG data (106 recordings, 60 s each and a third expert conducted the adjudication of differences. The independent annotators labeled each PPG signal with one of the following labels: excellent, acceptable or unfit for diagnosis. All indices were compared using Mahalanobis distance, linear discriminant analysis, quadratic discriminant analysis, and support vector machine with leave-one-out cross-validation. The skewness index outperformed the other seven indices in differentiating between excellent PPG and acceptable, acceptable combined with unfit, and unfit recordings, with overall F 1 scores of 86.0%, 87.2%, and 79.1%, respectively.

Optimal Signal Quality Index for Photoplethysmogram Signals.

Science.gov (United States)

Elgendi, Mohamed

2016-09-22

A photoplethysmogram (PPG) is a noninvasive circulatory signal related to the pulsatile volume of blood in tissue and is typically collected by pulse oximeters. PPG signals collected via mobile devices are prone to artifacts that negatively impact measurement accuracy, which can lead to a significant number of misleading diagnoses. Given the rapidly increased use of mobile devices to collect PPG signals, developing an optimal signal quality index (SQI) is essential to classify the signal quality from these devices. Eight SQIs were developed and tested based on: perfusion, kurtosis, skewness, relative power, non-stationarity, zero crossing, entropy, and the matching of systolic wave detectors. Two independent annotators annotated all PPG data (106 recordings, 60 s each) and a third expert conducted the adjudication of differences. The independent annotators labeled each PPG signal with one of the following labels: excellent, acceptable or unfit for diagnosis. All indices were compared using Mahalanobis distance, linear discriminant analysis, quadratic discriminant analysis, and support vector machine with leave-one-out cross-validation. The skewness index outperformed the other seven indices in differentiating between excellent PPG and acceptable, acceptable combined with unfit, and unfit recordings, with overall F 1 scores of 86.0%, 87.2%, and 79.1%, respectively.

Radon-222: tracer of geological systems dynamics. Methodology and signal processing, interpretation of radon-222 behaviour in active geological media

International Nuclear Information System (INIS)

Richon, Patrick

2011-01-01

detection of the gravimetric waves O1 and M2 in the sub-glacial laboratory of Argentiere tend to prove the relationship between mechanical deformations and variations of radon-222 activity. It is therefore theoretically possible to detect radon variations induced by the mechanical strain linked to an earthquake. However, hydrological effects (piston effect) cannot be not excluded as it is shown with data acquired on the Roselend site. On the Merapi volcano, we also demonstrate that the barometric wave S2, dissimulated in the radon activity and soils gas temperature, allows us to follow the evolution of the fracture self-sealing. This proved to be a precursory process of the 2006 eruption. These results demonstrate the strong potential of the measurement of radon-222 applied to the tracking of natural phenomena, providing, however, that one have a control on the instrumentation, a knowledge of physical processes associated with radon transport, and mostly that the tools of signals processing are applied. These tools are very promising for monitoring and understanding geodynamical processes. (author) [fr

Enhancing thermal reliability of fiber-optic sensors for bio-inspired applications at ultra-high temperatures

Science.gov (United States)

Kang, Donghoon; Kim, Heon-Young; Kim, Dae-Hyun

2014-07-01

The rapid growth of bio-(inspired) sensors has led to an improvement in modern healthcare and human-robot systems in recent years. Higher levels of reliability and better flexibility, essential features of these sensors, are very much required in many application fields (e.g. applications at ultra-high temperatures). Fiber-optic sensors, and fiber Bragg grating (FBG) sensors in particular, are being widely studied as suitable sensors for improved structural health monitoring (SHM) due to their many merits. To enhance the thermal reliability of FBG sensors, thermal sensitivity, generally expressed as αf + ξf and considered a constant, should be investigated more precisely. For this purpose, the governing equation of FBG sensors is modified using differential derivatives between the wavelength shift and the temperature change in this study. Through a thermal test ranging from RT to 900 °C, the thermal sensitivity of FBG sensors is successfully examined and this guarantees thermal reliability of FBG sensors at ultra-high temperatures. In detail, αf + ξf has a non-linear dependence on temperature and varies from 6.0 × 10-6 °C-1 (20 °C) to 10.6 × 10-6 °C-1 (650 °C). Also, FBGs should be carefully used for applications at ultra-high temperatures due to signal disappearance near 900 °C.

High Thermal Conductivity Materials

CERN Document Server

Shinde, Subhash L

2006-01-01

Thermal management has become a ‘hot’ field in recent years due to a need to obtain high performance levels in many devices used in such diverse areas as space science, mainframe and desktop computers, optoelectronics and even Formula One racing cars! Thermal solutions require not just taking care of very high thermal flux, but also ‘hot spots’, where the flux densities can exceed 200 W/cm2. High thermal conductivity materials play an important role in addressing thermal management issues. This volume provides readers a basic understanding of the thermal conduction mechanisms in these materials and discusses how the thermal conductivity may be related to their crystal structures as well as microstructures developed as a result of their processing history. The techniques for accurate measurement of these properties on large as well as small scales have been reviewed. Detailed information on the thermal conductivity of diverse materials including aluminum nitride (AlN), silicon carbide (SiC), diamond, a...

A novel polymer probe for Zn(II) detection with ratiometric fluorescence signal

Science.gov (United States)

Diao, Haipeng; Guo, Lixia; Liu, Wen; Feng, Liheng

2018-05-01

A conjugated polymer probe comprised of fluorene, quinolone and benzothiazole units was designed and synthesized by the Suzuki coupling reaction. Through the studies of photophysical and thermal properties, the polymer displays blue-emitting feature and good thermal stability. A ratiometric fluorescence signal of the probe for Zn(II) was observed in ethanol with a new emission peak at 555 nm. The probe possesses a high selectivity and sensitivity for Zn(II) during familiar metal ions in ethanol. The detection limit of the probe for Zn (II) is up to 10-8 mol/L. The electron distributions of the polymer before and after bonding with Zn (II) were investigated by the Gaussian 09 software, which agreed with the experimental results. Noticeably, based on the color property of the probe with Zn(II), a series of color test paper were developed for visual detecting Zn(II) ions. This work helps to provide a platform or pattern for the development of polymer fluorescence probe in the chemosensor field.

Signal Words

Science.gov (United States)

SIGNAL WORDS TOPIC FACT SHEET NPIC fact sheets are designed to answer questions that are commonly asked by the ... making decisions about pesticide use. What are Signal Words? Signal words are found on pesticide product labels, ...

Effect of thermal stresses on the mechanism of tooth pain.

Science.gov (United States)

Oskui, Iman Z; Ashtiani, Mohammed N; Hashemi, Ata; Jafarzadeh, Hamid

2014-11-01

Daily hot and cold thermal loadings on teeth may result in structural deformation, mechanical stress, and pain signaling. The aim of this study was to compare the adverse effects of hot and cold beverages on an intact tooth and, then, to provide physical evidence to support the hydrodynamic theory of tooth pain sensation mechanism. Three-dimensional finite element analysis was performed on a premolar model subjected to hot and cold thermal loadings. Elapsed times for heat diffusion and stress detection at the pulp-dentin junction were calculated as measures of the pain sensation. Extreme tensile stress within the enamel resulted in damage in cold loadings. Also, extreme values of stress at the pulpal wall occurred 21.6 seconds earlier than extreme temperatures in hot and cold loadings. The intact tooth was remarkably vulnerable to cold loading. Earlier changes in mechanical stress rather than temperature at the pulp-dentin junction indicate that the dental pain caused by hot or cold beverages may be based on the hydrodynamic theory. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.