WorldWideScience

Sample records for airborne thermal magnetic

  1. Evaluation of airborne thermal, magnetic, and electromagnetic characterization technologies

    International Nuclear Information System (INIS)

    The identification of Buried Structures (IBS) or Aerial Surveillance Project was initiated by the US Department of Energy (DOE) Office of Technology Development to demonstrate airborne methods for locating and identifying buried waste and ordnance at the Idaho National Engineering Laboratory (INEL). Two technologies were demonstrated: (a) a thermal infrared imaging system built by Martin Marietta Missile Systems and (b) a magnetic and electromagnetic (EM) geophysical surveying system operated by EBASCO Environmental. The thermal system detects small differences in ground temperature caused by uneven heating and cooling of the ground by the sun. Waste materials on the ground can be detected when the temperature of the waste is different than the background temperature. The geophysical system uses conventional magnetic and EM sensors. These sensors detect disturbances caused by magnetic or conductive waste and naturally occurring magnetic or conductive features of subsurface soils and rock. Both systems are deployed by helicopter. Data were collected at four INEL sites. Tests at the Naval Ordnance Disposal Area (NODA) were made to evaluate capabilities for detecting ordnance on the ground surface. Tests at the Cold Simulated Waste Demonstration Pit were made to evaluate capabilities for detecting buried waste at a controlled site, where the location and depth of buried materials are known. Tests at the Subsurface Disposal Area and Stationary Low-Power Reactor-1 burial area were made to evaluate capabilities for characterizing hazardous waste at sites that are typical of DOE buried waste sites nationwide

  2. Adaptive Restoration of Airborne Daedalus AADS1268 ATM Thermal Data

    International Nuclear Information System (INIS)

    To incorporate the georegistration and restoration processes into airborne data processing in support of U.S. Department of Energy's nuclear emergency response task, we developed an adaptive restoration filter for airborne Daedalus AADS1268 ATM thermal data based on the Wiener filtering theory. Preliminary assessment shows that this filter enhances the detectability of small weak thermal anomalies in AADS1268 thermal images

  3. Thermal Mapping Airborne Simulator for Small Satellite Sensor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A high performance, inexpensive, airborne simulator that will serve as the prototype for a small satellite based imaging system capable of mapping thermal anomalies...

  4. Airborne Magnetic Trackline and Survey Data (Vector and Scalar Observations)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA National Centers for Environmental Information (formerly National Geophysical Data Center) receive airborne magnetic survey data from US and non-US...

  5. Detection Range of Airborne Magnetometers in Magnetic Anomaly Detection

    Directory of Open Access Journals (Sweden)

    Chengjing Li

    2015-11-01

    Full Text Available Airborne magnetometers are utilized for the small-range search, precise positioning, and identification of the ferromagnetic properties of underwater targets. As an important performance parameter of sensors, the detection range of airborne magnetometers is commonly set as a fixed value in references regardless of the influences of environment noise, target magnetic properties, and platform features in a classical model to detect airborne magnetic anomalies. As a consequence, deviation in detection ability analysis is observed. In this study, a novel detection range model is proposed on the basis of classic detection range models of airborne magnetometers. In this model, probability distribution is applied, and the magnetic properties of targets and the environment noise properties of a moving submarine are considered. The detection range model is also constructed by considering the distribution of the moving submarine during detection. A cell-averaging greatest-of-constant false alarm rate test method is also used to calculate the detection range of the model at a desired false alarm rate. The detection range model is then used to establish typical submarine search probabilistic models. Results show that the model can be used to evaluate not only the effects of ambient magnetic noise but also the moving and geomagnetic features of the target and airborne detection platform. The model can also be utilized to display the actual operating range of sensor systems.

  6. Crop water-stress assessment using an airborne thermal scanner

    Science.gov (United States)

    Millard, J. P.; Jackson, R. D.; Reginato, R. J.; Idso, S. B.; Goettelman, R. C.

    1978-01-01

    An airborne thermal scanner was used to measure the temperature of a wheat crop canopy in Phoenix, Arizona. The results indicate that canopy temperatures acquired about an hour and a half past solar noon were well correlated with presunrise plant water tension, a parameter directly related to plant growth and development. Pseudo-colored thermal images reading directly in stress degree days, a unit indicative of crop irrigation needs and yield potential, were produced. The aircraft data showed significant within-field canopy temperature variability, indicating the superiority of the synoptic view provided by aircraft over localized ground measurements. The standard deviation between airborne and ground-acquired canopy temperatures was 2 C or less.

  7. Roof heat loss detection using airborne thermal infrared imagery

    Science.gov (United States)

    Kern, K.; Bauer, C.; Sulzer, W.

    2012-12-01

    As part of the Austrian and European attempt to reduce energy consumption and greenhouse gas emissions, thermal rehabilitation and the improvement of the energy efficiency of buildings became an important topic in research as well as in building construction and refurbishment. Today, in-situ thermal infrared measurements are routinely used to determine energy loss through the building envelope. However, in-situ thermal surveys are expensive and time consuming, and in many cases the detection of the amount and location of waste heat leaving building through roofs is not possible with ground-based observations. For some years now, a new generation of high-resolution thermal infrared sensors makes it possible to survey heat-loss through roofs at a high level of detail and accuracy. However, to date, comparable studies have mainly been conducted on buildings with uniform roof covering and provided two-dimensional, qualitative information. This pilot study aims to survey the heat-loss through roofs of the buildings of the University of Graz (Austria) campus by using high-resolution airborne thermal infrared imagery (TABI 1800 - Thermal Airborne Broadband imager). TABI-1800 acquires data in a spectral range from 3.7 - 4.8 micron, a thermal resolution of 0.05 °C and a spatial resolution of 0.6 m. The remote sensing data is calibrated to different roof coverings (e.g. clay shingle, asphalt shingle, tin roof, glass) and combined with a roof surface model to determine the amount of waste heat leaving the building and to identify hot spots. The additional integration of information about the conditions underneath the roofs into the study allows a more detailed analysis of the upward heat flux and is a significant improvement of existing methods. The resulting data set provides useful information to the university facility service for infrastructure maintenance, especially in terms of attic and roof insulation improvements. Beyond that, the project is supposed to raise public

  8. Air-borne noise of thermal module and system for notebook personal computers:experimental study

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Thermal performance is the most important issue to be considered when a thermal module is designed for a notebook personal computer (PC).Because the fan causes air-borne noise and affects the user's comfort,the acoustic characteristics of the module attract more attention.Experiments were conducted to study the noise sources,the noise characteristic and the main factors influencing the noise level.The difference between the air-borne noise of the thermal module and the whole computer system was analyzed and its propagating characteristics were derived.The influence of I/O ports on the air-borne noise was also studied experimentally.

  9. International Symposium on Airborne Geophysics

    Science.gov (United States)

    Mogi, Toru; Ito, Hisatoshi; Kaieda, Hideshi; Kusunoki, Kenichiro; Saltus, Richard W.; Fitterman, David V.; Okuma, Shigeo; Nakatsuka, Tadashi

    2006-05-01

    Airborne geophysics can be defined as the measurement of Earth properties from sensors in the sky. The airborne measurement platform is usually a traditional fixed-wing airplane or helicopter, but could also include lighter-than-air craft, unmanned drones, or other specialty craft. The earliest history of airborne geophysics includes kite and hot-air balloon experiments. However, modern airborne geophysics dates from the mid-1940s when military submarine-hunting magnetometers were first used to map variations in the Earth's magnetic field. The current gamut of airborne geophysical techniques spans a broad range, including potential fields (both gravity and magnetics), electromagnetics (EM), radiometrics, spectral imaging, and thermal imaging.

  10. Airborne Thematic Thermal InfraRed and Electro-Optical Imaging System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The innovation is an advanced Airborne Thematic Thermal InfraRed and Electro-Optical Imaging System (ATTIREOIS). ATTIREOIS sensor payload consists of two sets of...

  11. Field and Thermal Characteristics of Magnetizing Fixture

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This paper describes field modeling and thermal modeling for magnetizing fixture. As the detailed characteristics of magnetizing fixture can be obtained, the efficient design of magnetizer which produce desired magnet will be possible using our modeling. For field modeling finite-element analysis is used as part of the design and analysis process for magnetizing fixture. The thermal modeling method of magnetizing fixture resistor uses multi-lumped model with equivalent thermal resistance and thermal capacitance.

  12. NASA Goddard’s LiDAR, Hyperspectral and Thermal (G-LiHT) Airborne Imager

    OpenAIRE

    Vuong Ly; Montesano, Paul M.; Kenneth J. Ranson; Jeffrey G. Masek; Joel T. McCorkel; Douglas C. Morton; Elizabeth M. Middleton; Ross F. Nelson; Lawrence A. Corp; Cook, Bruce D

    2013-01-01

    The combination of LiDAR and optical remotely sensed data provides unique information about ecosystem structure and function. Here, we describe the development, validation and application of a new airborne system that integrates commercial off the shelf LiDAR hyperspectral and thermal components in a compact, lightweight and portable system. Goddard’s LiDAR, Hyperspectral and Thermal (G-LiHT) airborne imager is a unique system that permits simultaneous measurements of vegetation structure, fo...

  13. Magnetic Approaches to Measuring and Mitigating Airborne Particulate Pollution

    Science.gov (United States)

    Maher, B.

    2014-12-01

    Human exposure to airborne particulate matter (PM) generates adverse human health impacts at all life stages from the embryonic to the terminal, including damage to respiratory and cardiovascular health, and neurodevelopment and cognitive function. Detailed understanding of the causal links between PM exposure and specific health impacts, and possible means to reduce PM exposure require knowledge of PM concentrations, compositions and sources at the fine-scale; i.e. beyond the current resolution of spatially-sparse conventional PM monitoring, non-unique elemental analyses, or poorly-validated PM modelling. Magnetically-ordered iron oxide minerals appear to be a ubiquitous component of urban PM. These minerals derive partly from the presence of iron impurities in fuels, which form, upon combustion, a non-volatile residue, often dominated by magnetite, within glassy, spherical condensates. Iron-rich, magnetic PM also arises from abrasion from vehicle components, including disk brakes, and road dust. The ubiquity and diversity of these magnetic PM phases, and the speed and sensitivity of magnetic analyses (down to trace concentrations), makes possible rapid, cost-effective magnetic characterization and quantification of PM, a field of study which has developed rapidly across the globe over the last 2 decades. Magnetic studies of actively-sampled PM, on filters, and passively-sampled PM, on tree leaves and other depositional surfaces, can be used to: monitor and map at high spatial resolution ambient PM concentrations; address the controversial issue of the efficacy of PM capture by vegetation; and add a new, discriminatory dimension to PM source apportionment.

  14. Airborne magnetic and gamma-ray data acquisition

    International Nuclear Information System (INIS)

    Current aeromagnetic data acquisition has benefited from improvements in measurement precision and compensation systems for removing with closer line spacing than previously, and this has stimulated a demand for lower survey altitudes with flight heights of the order of 60-80 m now common. Radiometric recording of 256 channels of gamma-ray data is now virtually standard and in-flight stabilisation of these systems has improved markedly. Digital acquisition systems are now designed to facilitate both in-flight and post-flight verification of the data. This article briefly outlines he history of the acquisition equipment used in the earlier surveys and details the current sate-of-the-art technology and methodology used in airborne magnetic and gamma-ray surveys. 9 refs., 1 tab., 2 figs

  15. Use of airborne thermal imagery to detect and monitor inshore oil spill residues during darkness hours

    International Nuclear Information System (INIS)

    Trials were conducted using an airborne video system operating in the visible, near-infrared, and thermal wavelengths to detect two known oil spill releases during darkness at a distance of 10 nautical miles from the shore in St. Vincent's Gulf, South Australia. The oil spills consisted of two 20-liter samples released at 2-h intervals, one sample consisted of paraffinic neutral material and the other of automotive diesel oil. A tracking buoy was sent overboard in conjunction with the release of sample 1, and its movement monitored by satellite relay. Both oil residues were overflown by a light aircraft equipped with thermal, visible, and infrared imagers at a period of approximately 1 h after the release of the second oil residue. Trajectories of the oil residue releases were also modeled and the results compared to those obtained by the airborne video and the tracking buoy. Airborne imagery in the thermal wavelengths successfully located and mapped both oil residue samples during nighttime conditions. Results from the trial suggest that the most advantageous technique would be the combined use of the tracking beacon to obtain an approximate location of the oil spill and the airborne imagery to ascertain its extent and characteristics

  16. Thermal to electricity conversion using thermal magnetic properties

    Science.gov (United States)

    West, Phillip B [Idaho Falls, ID; Svoboda, John [Idaho Falls, ID

    2010-04-27

    A system for the generation of Electricity from Thermal Energy using the thermal magnetic properties of a Ferromagnetic, Electrically Conductive Material (FECM) in one or more Magnetic Fields. A FECM is exposed to one or more Magnetic Fields. Thermal Energy is applied to a portion of the FECM heating the FECM above its Curie Point. The FECM, now partially paramagnetic, moves under the force of the one or more Magnetic Fields. The movement of the FECM induces an electrical current through the FECM, generating Electricity.

  17. Remote Sensing of Soil Moisture in Vineyards Using Airborne and Ground-Based Thermal Inertia Data

    Directory of Open Access Journals (Sweden)

    Ralph Brown

    2013-07-01

    Full Text Available Thermal remote sensing of soil moisture in vineyards is a challenge. The grass-covered soil, in addition to a standing grape canopy, create complex patterns of heating and cooling and increase the surface temperature variability between vine rows. In this study, we evaluate the strength of relationships between soil moisture, mechanical resistance and thermal inertia calculated from the drop of surface temperature during a clear sky night over a vineyard in the Niagara region. We utilized data from two sensors, an airborne thermal camera (height ≈ 500 m a.g.l. and a handheld thermal gun (height ≈ 1 m a.g.l., to explore the effects of different field of views and the high inter-row temperature variability. Spatial patterns of soil moisture correlated more with estimated thermal inertia than with surface temperature recorded at sunrise or sunset. Despite the coarse resolution of airborne thermal inertia images, it performed better than estimates from the handheld thermal gun. Between-row variation was further analyzed using a linear mixed-effects model. Despite the limited spatial variability of soil properties within a single vineyard, the magnitudes of the model coefficients for soil moisture and mechanical resistance are encouraging indicators of the utility of thermal inertia in vineyard management.

  18. Numerical analysis of thermally actuated magnets for magnetization of superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Li Quan; Yan Yu; Rawlings, Colin; Coombs, Tim, E-mail: ql229@cam.ac.u [EPEC Superconductivity Group, Engineering Department, University of Cambridge, Trumpington Street. Cambridge, CB2 1PZ (United Kingdom)

    2010-06-01

    Superconductors, such as YBCO bulks, have extremely high potential magnetic flux densities, comparing to rare earth magnets. Therefore, the magnetization of superconductors has attracted broad attention and contribution from both academic research and industry. In this paper, a novel technique is proposed to magnetize superconductors. Unusually, instead of using high magnetic fields and pulses, repeatedly magnetic waves with strength of as low as rare earth magnets are applied. These magnetic waves, generated by thermally controlling a Gadolinium (Gd) bulk with a rare earth magnet underneath, travel over the flat surface of a YBCO bulk and get trapped little by little. Thus, a very small magnetic field can be used to build up a very large magnetic field. In this paper, the modelling results of thermally actuated magnetic waves are presented showing how to transfer sequentially applied thermal pulses into magnetic waves. The experiment results of the magnetization of YBCO bulk are also presented to demonstrate how superconductors are progressively magnetized by small magnetic field

  19. Airborne magnetic mapping of volcanic areas - state-of-the-art and future perspectives

    Science.gov (United States)

    Supper, Robert; Paoletti, Valeria; Okuma, Shigeo

    2015-04-01

    Traditionally airborne magnetics surveys in volcanology are used for mapping regional geological features, fault zones and to develop a magnetic model of the volcanic subsurface. Within an Austrian-Italian-Japanese cooperation, several volcanic areas including Mt. Vesuvius, Ischia, Campi Flegreii and Aeolian Islands in Italy and Socorro Island in Mexico were mapped by high-resolution magnetic mapping during the last 15 years. In this paper, general conclusions from this long-term cooperation project on airborne magnetics in volcanic areas will be summarised. Basically the results showed the results from airborne magnetics could be used for three major purposes: 1. Developing a rough model for the magnetisation below the volcano down to several kilometres by applying advanced magnetic inversion algorithms helped to define the possible depth of the current or past magma chamber. Due to the complexity of the subsurface of volcanic areas, inversion of data was much dependent on constraints coming from other geoscientific disciplines. 2. After applying certain steps of reduction (topographic correction, field transformation) and a combination of source selective filtering, important regional structural trends could be derived from the alignment of the residual magnetic anomalies. 3. On the other hand during recent years, research has also focused on repeated measurements of the magnetic field of volcanic areas (differential in respect of time = differential magnetic measurements - DMM) using airborne sensors. Long-term temporal magnetic field variations in active volcanic areas can be caused by a changing size of the magma chamber or a general rise in temperature. This is caused by the fact that magnetization disappears, when a magnetic material is warmed up over a certain temperature (Curie- temperature). In consequence the resulting total magnetic field changes. Therefore, determining areas showing changes in the magnetic field could help to select areas where a

  20. Anisotropic thermal conductivity of magnetic fluids

    Institute of Scientific and Technical Information of China (English)

    Xiaopeng Fang; Yimin Xuan; Qiang Li

    2009-01-01

    Considering the forces acting on the particles and the motion of the particles, this study uses a numerical simulation to investigate the three-dimensional microstructure of the magnetic fluids in the presence of an external magnetic field. A method is proposed for predicting the anisotropic thermal conductivity of magnetic fluids. By introducing an anisotropic structure parameter which characterizes the non-uniform distribution of particles suspended in the magnetic fluids, the traditional Maxwell formula is modified and extended to calculate anisotropic thermal conductivity of the magnetic fluids. The results show that in the presence of an external magnetic field the magnetic nanoparticles form chainlike clusters along the direction of the external magnetic field, which leads to the fact that the thermal conduc-tivity of the magnetic fluid along the chain direction is bigger than that along other directions. The thermal conductivity of the magnetic fluids presents an anisotropic feature. With the increase of the magnetic field strength the chainlike clusters in the magnetic fluid appear to be more obvious, so that the anisotropic feature of heat conduction in the fluids becomes more evident.

  1. Thermal management of closed computer modules utilizing high density circuitry. [in Airborne Information Management System

    Science.gov (United States)

    Hoadley, A. W.; Porter, A. J.

    1990-01-01

    This paper presents data on a preliminary analysis of the thermal dynamic characteristics of the Airborne Information Management System (AIMS), which is a continuing design project at NASA Dryden. The analysis established the methods which will be applied to the actual AIMS boards as they become available. The paper also describes the AIMS liquid cooling system design and presents a thermodynamic computer model of the AIMS cooling system, together with an experimental validation of this model.

  2. Thermal radiation from magnetic neutron star surfaces

    CERN Document Server

    Pérez-Azorin, J F; Pons, J A

    2005-01-01

    We investigate the thermal emission from magnetic neutron star surfaces in which the cohesive effects of the magnetic field have produced the condensation of the atmosphere and the external layers. This may happen for sufficiently cool atmospheres with moderately intense magnetic fields. The thermal emission from an isothermal bare surface of a neutron star shows no remarkable spectral features, but it is significantly depressed at energies below some threshold energy. However, since the thermal conductivity is very different in the normal and parallel directions to the magnetic field lines, the presence of the magnetic field is expected to produce a highly anisotropic temperature distribution, depending on the magnetic field geometry. In this case, the observed flux of such an object looks very similar to a BB spectrum, but depressed in a nearly constant factor at all energies. This results in a systematic underestimation of the area of the emitter (and therefore its size) by a factor 5-10 (2-3).

  3. Multispectral thermal airborne TASI-600 data to study the Pompeii (IT) archaeological area

    Science.gov (United States)

    Palombo, Angelo; Pascucci, Simone; Pergola, Nicola; Pignatti, Stefano; Santini, Federico; Soldovieri, Francesco

    2016-04-01

    The management of archaeological areas refers to the conservation of the ruins/buildings and the eventual prospection of new areas having an archaeological potential. In this framework, airborne remote sensing is a well-developed geophysical tool for supporting the archaeological surveys of wide areas. The spectral regions applied in archaeological remote sensing spans from the VNIR to the TIR. In particular, the archaeological thermal imaging considers that materials absorb, emit, transmit, and reflect the thermal infrared radiation at different rate according to their composition, density and moisture content. Despite its potential, thermal imaging in archaeological applications are scarce. Among them, noteworthy are the ones related to the use of Landsat and ASTER [1] and airborne remote sensing [2, 3, 4 and 5]. In view of these potential in Cultural Heritage applications, the present study aims at analysing the usefulness of the high spatial resolution thermal imaging on the Pompeii archaeological park. To this purpose TASI-600 [6] airborne multispectral thermal imagery (32 channels from 8 to 11.5 nm with a spectral resolution of 100nm and a spatial resolution of 1m/pixel) was acquired on December the 7th, 2015. Airborne survey has been acquired to get useful information on the building materials (both ancient and of consolidation) characteristics and, whenever possible, to retrieve quick indicators on their conservation status. Thermal images will be, moreover, processed to have an insight of the critical environmental issues impacting the structures (e.g. moisture). The proposed study shows the preliminary results of the airborne deployments, the pre-processing of the multispectral thermal imagery and the retrieving of accurate land surface temperatures (LST). LST map will be analysed to describe the thermal pattern of the city of Pompeii and detect any thermal anomalies. As far as the ongoing TASI-600 sensors pre-processing, it will include: (a) radiometric

  4. Thermal modeling of Fresca2 magnet

    CERN Document Server

    Pietrowicz, S

    2011-01-01

    This report presents the thermal modeling of the Nb3Sn magnet called Fresca2 within the EuCARD-HFM project. The goal of this study is to predict the thermal behavior of the magnet and to calculate the maximum temperature difference in the magnet structure during steady and transient state conditions. Results of the maximum temperature difference are compared with the temperature margin allowed. The steady state thermal calculations of the magnet are performed with AC losses due to ramp rate and homogeneous dissipation of heat as input heat loads. The transient calculations model the cool-down process. The thermal modeling was performed for several scenarios for steady and unsteady processes and for two base temperatures of 1.9 K and 4.2 K.

  5. Airborne Optical and Thermal Remote Sensing for Wildfire Detection and Monitoring.

    Science.gov (United States)

    Allison, Robert S; Johnston, Joshua M; Craig, Gregory; Jennings, Sion

    2016-01-01

    For decades detection and monitoring of forest and other wildland fires has relied heavily on aircraft (and satellites). Technical advances and improved affordability of both sensors and sensor platforms promise to revolutionize the way aircraft detect, monitor and help suppress wildfires. Sensor systems like hyperspectral cameras, image intensifiers and thermal cameras that have previously been limited in use due to cost or technology considerations are now becoming widely available and affordable. Similarly, new airborne sensor platforms, particularly small, unmanned aircraft or drones, are enabling new applications for airborne fire sensing. In this review we outline the state of the art in direct, semi-automated and automated fire detection from both manned and unmanned aerial platforms. We discuss the operational constraints and opportunities provided by these sensor systems including a discussion of the objective evaluation of these systems in a realistic context. PMID:27548174

  6. Airborne Optical and Thermal Remote Sensing for Wildfire Detection and Monitoring

    Directory of Open Access Journals (Sweden)

    Robert S. Allison

    2016-08-01

    Full Text Available For decades detection and monitoring of forest and other wildland fires has relied heavily on aircraft (and satellites. Technical advances and improved affordability of both sensors and sensor platforms promise to revolutionize the way aircraft detect, monitor and help suppress wildfires. Sensor systems like hyperspectral cameras, image intensifiers and thermal cameras that have previously been limited in use due to cost or technology considerations are now becoming widely available and affordable. Similarly, new airborne sensor platforms, particularly small, unmanned aircraft or drones, are enabling new applications for airborne fire sensing. In this review we outline the state of the art in direct, semi-automated and automated fire detection from both manned and unmanned aerial platforms. We discuss the operational constraints and opportunities provided by these sensor systems including a discussion of the objective evaluation of these systems in a realistic context.

  7. Thermal potentiation of chemotherapy by magnetic nanoparticles

    OpenAIRE

    Torres-Lugo, Madeline; Rinaldi, Carlos

    2013-01-01

    Clinical studies have demonstrated the effectiveness of hyperthermia as an adjuvant for chemotherapy and radiotherapy. However, significant clinical challenges have been encountered, such as a broader spectrum of toxicity, lack of patient tolerance, temperature control and significant invasiveness. Hyperthermia induced by magnetic nanoparticles in high-frequency oscillating magnetic fields, commonly termed magnetic fluid hyperthermia, is a promising form of heat delivery in which thermal ener...

  8. Thermal diffusivity measurements in magnetic field

    International Nuclear Information System (INIS)

    This paper presents the first observation of thermal diffusivity in magnetic field on superconducting oxides. The measurements are performed on sintered samples using a high resolution a.c. technique from 30 to 120 K in magnetic field up to 7 T. In magnetic field higher than 1 T the thermal diffusivity below the critical temperature decreases and the authors suggest this is due to the scattering between the phonons and the flux lines inside the grains. The cross section σ related to such a scattering is calculated; the authors obtain values from 1 to 7 x 10-7 cm when the temperature increases from 30 to 70 K

  9. Thermally activated magnetization reversal in magnetic tunnel junctions

    Institute of Scientific and Technical Information of China (English)

    Zhou Guang-Hong; Wang Yin-Gang; Qi Xian-Jin; Li Zi-Quan; Chen Jian-Kang

    2009-01-01

    In this paper, the magnetization reversal of the ferromagnetic layers in the lrMn/CoFe/AlOx/CoFe magnetic tunnel junction has been investigated using bulk magnetometry. The films exhibit very complex magnetization processes and reversal mechanism. Thermal activation phenomena such as the training effect, the asymmetry of reversal, the loop broadening and the decrease of exchange field while holding the film at negative saturation have been observed on the hysteresis loops of the pinned ferromagnetic layer while not on those of the free ferromagnetic layer. The thermal activation phenomena observed can be explained by the model of two energy barrier distributions with different time constants.

  10. A preliminary interpretation of Tellus airborne magnetic and electromagnetic data for Northern Ireland

    OpenAIRE

    Chacksfield, B.C.

    2010-01-01

    An airborne geophysical survey of the whole of Northern Ireland was flown in 2005 and 2006 as part of the Tellus project. This project was funded by the Northern Ireland Department of Enterprise Trade and Investment and by the Rural Development Programme through the Northern Ireland Programme for Building Sustainable Prosperity (www.tellus.detini.gov.uk). The aircraft used was a De Havilland Twin Otter which carried magnetic, electromagnetic and radiometric sensors. It was oper...

  11. Maneuvering thermal conductivity of magnetic nanofluids by tunable magnetic fields

    Science.gov (United States)

    Patel, Jaykumar; Parekh, Kinnari; Upadhyay, R. V.

    2015-06-01

    We report an experimental investigation of magnetic field dependent thermal conductivity of a transformer oil base magnetic fluid as a function of volume fractions. In the absence of magnetic field, thermal conductivity increases linearly with an increase in volume fraction, and magnitude of thermal conductivity thus obtained is lower than that predicted by Maxwell's theory. This reveals the presence of clusters/oligomers in the system. On application of magnetic field, it exhibits a non-monotonous increase in thermal conductivity. The results are interpreted using the concept of a two-step homogenization method (which is based on differential effective medium theory). The results show a transformation of particle cluster configuration from long chain like prolate shape to the aggregated drop-like structure with increasing concentration as well as a magnetic field. The aggregated drop-like structure for concentrated system is supported by optical microscopic images. This shape change of clusters reduces thermal conductivity enhancement. Moreover, this structure formation is observed as a dynamic phenomenon, and at 226 mT field, the length of the structure extends with time, becomes maximum, and then reduces. This change results in the increase or decrease of thermal conductivity.

  12. NASA Goddards LiDAR, Hyperspectral and Thermal (G-LiHT) Airborne Imager

    Science.gov (United States)

    Cook, Bruce D.; Corp, Lawrence A.; Nelson, Ross F.; Middleton, Elizabeth M.; Morton, Douglas C.; McCorkel, Joel T.; Masek, Jeffrey G.; Ranson, Kenneth J.; Ly, Vuong; Montesano, Paul M.

    2013-01-01

    The combination of LiDAR and optical remotely sensed data provides unique information about ecosystem structure and function. Here, we describe the development, validation and application of a new airborne system that integrates commercial off the shelf LiDAR hyperspectral and thermal components in a compact, lightweight and portable system. Goddard's LiDAR, Hyperspectral and Thermal (G-LiHT) airborne imager is a unique system that permits simultaneous measurements of vegetation structure, foliar spectra and surface temperatures at very high spatial resolution (approximately 1 m) on a wide range of airborne platforms. The complementary nature of LiDAR, optical and thermal data provide an analytical framework for the development of new algorithms to map plant species composition, plant functional types, biodiversity, biomass and carbon stocks, and plant growth. In addition, G-LiHT data enhance our ability to validate data from existing satellite missions and support NASA Earth Science research. G-LiHT's data processing and distribution system is designed to give scientists open access to both low- and high-level data products (http://gliht.gsfc.nasa.gov), which will stimulate the community development of synergistic data fusion algorithms. G-LiHT has been used to collect more than 6,500 km2 of data for NASA-sponsored studies across a broad range of ecoregions in the USA and Mexico. In this paper, we document G-LiHT design considerations, physical specifications, instrument performance and calibration and acquisition parameters. In addition, we describe the data processing system and higher-level data products that are freely distributed under NASA's Data and Information policy.

  13. NASA Goddard’s LiDAR, Hyperspectral and Thermal (G-LiHT Airborne Imager

    Directory of Open Access Journals (Sweden)

    Vuong Ly

    2013-08-01

    Full Text Available The combination of LiDAR and optical remotely sensed data provides unique information about ecosystem structure and function. Here, we describe the development, validation and application of a new airborne system that integrates commercial off the shelf LiDAR hyperspectral and thermal components in a compact, lightweight and portable system. Goddard’s LiDAR, Hyperspectral and Thermal (G-LiHT airborne imager is a unique system that permits simultaneous measurements of vegetation structure, foliar spectra and surface temperatures at very high spatial resolution (~1 m on a wide range of airborne platforms. The complementary nature of LiDAR, optical and thermal data provide an analytical framework for the development of new algorithms to map plant species composition, plant functional types, biodiversity, biomass and carbon stocks, and plant growth. In addition, G-LiHT data enhance our ability to validate data from existing satellite missions and support NASA Earth Science research. G-LiHT’s data processing and distribution system is designed to give scientists open access to both low- and high-level data products (http://gliht.gsfc.nasa.gov, which will stimulate the community development of synergistic data fusion algorithms. G-LiHT has been used to collect more than 6,500 km2 of data for NASA-sponsored studies across a broad range of ecoregions in the USA and Mexico. In this paper, we document G-LiHT design considerations, physical specifications, instrument performance and calibration and acquisition parameters. In addition, we describe the data processing system and higher-level data products that are freely distributed under NASA’s Data and Information policy.

  14. Multispectral thermal airborne TASI-600 data to study the Pompeii (IT) archaeological area

    Science.gov (United States)

    Palombo, Angelo; Pascucci, Simone; Pergola, Nicola; Pignatti, Stefano; Santini, Federico; Soldovieri, Francesco

    2016-04-01

    The management of archaeological areas refers to the conservation of the ruins/buildings and the eventual prospection of new areas having an archaeological potential. In this framework, airborne remote sensing is a well-developed geophysical tool for supporting the archaeological surveys of wide areas. The spectral regions applied in archaeological remote sensing spans from the VNIR to the TIR. In particular, the archaeological thermal imaging considers that materials absorb, emit, transmit, and reflect the thermal infrared radiation at different rate according to their composition, density and moisture content. Despite its potential, thermal imaging in archaeological applications are scarce. Among them, noteworthy are the ones related to the use of Landsat and ASTER [1] and airborne remote sensing [2, 3, 4 and 5]. In view of these potential in Cultural Heritage applications, the present study aims at analysing the usefulness of the high spatial resolution thermal imaging on the Pompeii archaeological park. To this purpose TASI-600 [6] airborne multispectral thermal imagery (32 channels from 8 to 11.5 nm with a spectral resolution of 100nm and a spatial resolution of 1m/pixel) was acquired on December the 7th, 2015. Airborne survey has been acquired to get useful information on the building materials (both ancient and of consolidation) characteristics and, whenever possible, to retrieve quick indicators on their conservation status. Thermal images will be, moreover, processed to have an insight of the critical environmental issues impacting the structures (e.g. moisture). The proposed study shows the preliminary results of the airborne deployments, the pre-processing of the multispectral thermal imagery and the retrieving of accurate land surface temperatures (LST). LST map will be analysed to describe the thermal pattern of the city of Pompeii and detect any thermal anomalies. As far as the ongoing TASI-600 sensors pre-processing, it will include: (a) radiometric

  15. An airborne thematic thermal infrared and electro-optical imaging system

    Science.gov (United States)

    Sun, Xiuhong; Shu, Peter

    2011-08-01

    This paper describes an advanced Airborne Thematic Thermal InfraRed and Electro-Optical Imaging System (ATTIREOIS) and its potential applications. ATTIREOIS sensor payload consists of two sets of advanced Focal Plane Arrays (FPAs) - a broadband Thermal InfraRed Sensor (TIRS) and a four (4) band Multispectral Electro-Optical Sensor (MEOS) to approximate Landsat ETM+ bands 1,2,3,4, and 6, and LDCM bands 2,3,4,5, and 10+11. The airborne TIRS is 3-axis stabilized payload capable of providing 3D photogrammetric images with a 1,850 pixel swathwidth via pushbroom operation. MEOS has a total of 116 million simultaneous sensor counts capable of providing 3 cm spatial resolution multispectral orthophotos for continuous airborne mapping. ATTIREOIS is a complete standalone and easy-to-use portable imaging instrument for light aerial vehicle deployment. Its miniaturized backend data system operates all ATTIREOIS imaging sensor components, an INS/GPS, and an e-Gimbal™ Control Electronic Unit (ECU) with a data throughput of 300 Megabytes/sec. The backend provides advanced onboard processing, performing autonomous raw sensor imagery development, TIRS image track-recovery reconstruction, LWIR/VNIR multi-band co-registration, and photogrammetric image processing. With geometric optics and boresight calibrations, the ATTIREOIS data products are directly georeferenced with an accuracy of approximately one meter. A prototype ATTIREOIS has been configured. Its sample LWIR/EO image data will be presented. Potential applications of ATTIREOIS include: 1) Providing timely and cost-effective, precisely and directly georeferenced surface emissive and solar reflective LWIR/VNIR multispectral images via a private Google Earth Globe to enhance NASA's Earth science research capabilities; and 2) Underflight satellites to support satellite measurement calibration and validation observations.

  16. EMAG2: A 2-arc min resolution Earth Magnetic Anomaly Grid compiled from satellite, airborne, and marine magnetic measurements

    Science.gov (United States)

    Maus, S.; Barckhausen, U.; Berkenbosch, H.; Bournas, N.; Brozena, J.; Childers, V.; Dostaler, F.; Fairhead, J.D.; Finn, C.; von Frese, R.R.B; Gaina, C.; Golynsky, S.; Kucks, R.; Lu, Hai; Milligan, P.; Mogren, S.; Muller, R.D.; Olesen, O.; Pilkington, M.; Saltus, R.; Schreckenberger, B.; Thebault, E.; Tontini, F.C.

    2009-01-01

    A global Earth Magnetic Anomaly Grid (EMAG2) has been compiled from satellite, ship, and airborne magnetic measurements. EMAG2 is a significant update of our previous candidate grid for the World Digital Magnetic Anomaly Map. The resolution has been improved from 3 arc min to 2 arc min, and the altitude has been reduced from 5 km to 4 km above the geoid. Additional grid and track line data have been included, both over land and the oceans. Wherever available, the original shipborne and airborne data were used instead of precompiled oceanic magnetic grids. Interpolation between sparse track lines in the oceans was improved by directional gridding and extrapolation, based on an oceanic crustal age model. The longest wavelengths (>330 km) were replaced with the latest CHAMP satellite magnetic field model MF6. EMAG2 is available at http://geomag.org/models/EMAG2 and for permanent archive at http://earthref.org/ cgi-bin/er.cgi?s=erda.cgi?n=970. ?? 2009 by the American Geophysical Union.

  17. INTERPRETATION OF AIRBORNE ELECTROMAGNETIC AND MAGNETIC DATA IN THE 600 AREA

    Energy Technology Data Exchange (ETDEWEB)

    CUMMINS GD

    2010-11-11

    As part of the 200-PO-1 Phase I geophysical surveys, Fugro Airborne Surveys was contracted to collect airborne electromagnetic (EM) and magnetic surveys of the Hanford Site 600 Area. Two helicopter survey systems were used with the HeliGEOTEM{reg_sign} time domain portion flown between June 19th and June 20th, 2008, and the RESOLVE{reg_sign} frequency domain portion was flown from June 29th to July 1st, 2008. Magnetic data were acquired contemporaneously with the electromagnetic surveys using a total-field cesium vapor magnetometer. Approximately 925 line kilometers (km) were flown using the HeliGEOTEM{reg_sign} II system and 412 line kilometers were flown using the RESOLVE{reg_sign} system. The HeliGEOTEM system has an effective penetration of roughly 250 meters into the ground and the RESOLVE system has an effective penetration of roughly 60 meters. Acquisition parameters and preliminary results are provided in SGW-39674, Airborne Electromagnetic Survey Report, 200-PO-1 Groundwater Operable Unit, 600 Area, Hanford Site. Airborne data are interpreted in this report in an attempt to identify areas of likely preferential groundwater flow within the aquifer system based on the presence of paleochannels or fault zones. The premise for the interpretation is that coarser-grained intervals have filled in scour channels created by episodic catastrophic flood events during the late Pleistocene. The interpretation strategy used the magnetic field anomaly data and existing bedrock maps to identify likely fault or lineament zones. Combined analysis of the magnetic, 60-Hz noise monitor, and flight-altitude (radar) data were used to identify zones where EM response is more likely due to cultural interference and or bedrock structures. Cross-sectional and map view presentations of the EM data were used to identify more electrically resistive zones that likely correlate with coarser-grained intervals. The resulting interpretation identifies one major northwest-southeast trending

  18. Elemental analysis of airborne particulate by using thermal and epithermal neutron activation

    International Nuclear Information System (INIS)

    Thermal neutron activation analysis was used to determine Al, Br, Ca, Cl, Mn, Na, V, and Ti concentrations, whereas epithermal neutron activation analysis was used to determine Cu, I and Si concentrations. Counting by Compton suppression both in thermal neutron activation and epithermal neutron activation analysis showed the significantly different on detection limit of element compare with normal counting system. It revealed counting by Compton suppression gave better result. The enrichment factor of elements indicated that V and Mn were enriched in several fine particulate samples. Ca, Si and Na were not enriched, whereas Br, I and Cl were enriched in fine airborne particulate or in coarse one. It was found that Cl and Na did not have correlation, while Br and I showed the same enrichment the same enrichment trend and high correlation (0,9). It means that Br and I were from the same pollutant source. It could concluded that the thermal neutron and epithermal neutron activations analysis combined with counting by Compton suppression could enhance sensitivity of analysis of elemental air bone particulate that was very useful in air pollution study. Key words : activation analysis, thermal neutron, epithermal neutron, Compton

  19. Thermal Photons From Magnetized Bare Strange Stars

    CERN Document Server

    Méndez, Enrique Moreno; Patiño, Leonardo; Ortega, Patricia

    2013-01-01

    A plasma made out of strange-quark matter (SQM) and electrons, has a rather high plasma frequency (>20 MeV). Thus, a compact star made of such material all the way up to its surface, i.e., a bare strange star, would be unable to radiate away its thermal emission. We use the MIT-bag model and assume that SQM is the ground state of nuclear matter at high density. We investigate whether the presence of a magnetic field will allow propagation of radiation at frequencies below the SQM plasma frequencies. Hence, we study the presence of gyrofrequencies in a SQM plasma permeated by a strong magnetic field (B > 10^{12} G). We find that small regions in the frequency spectrum allow radiation propagation due to the presence of the magnetic fields. It is likely that narrow bands of radiation would likely be observable from magnetized bare strange stars .

  20. EMAG2. A 2-arc-minute resolution Earth magnetic anomaly grid compiled from satellite, airborne and marine magnetic measurements

    International Nuclear Information System (INIS)

    Complete text of publication follows. Airborne and marine magnetic data have been collected for more than half a century, providing extensive coverage of the Earth. Due to the changing main field from the Earth's core, and due to differences in quality and coverage, combining these data to a consistent global magnetic anomaly grid is challenging. A key ingredient is the long wavelength magnetic field observed by the low-orbiting CHAMP satellite. To produce a homogeneous grid, the marine and aeromagnetic trackline data are first line-leveled and then merged with the existing grids of continental-scale compilations by Least Squares Collocation. The method takes the anisotropy of the oceanic magnetic field into account. This leads to an improved representation of oceanic magnetic lineations and allows for the interpolation between adjacent tracks in sparsely surveyed regions, particularly in the southern oceans. In the final processing step the short-to- intermediate wavelengths of the near-surface grid are merged with the latest CHAMP satellite magnetic anomaly model MF6 (http://geomag.org/models/MF6.html). In analogy to NGDC's 2-arc-minute resolution ETOPO2 grid, the new magnetic anomaly grid is named EMAG2. The grid is available in digital form and as plug-ins for NASA World Wind, Google Earth and Google Maps at http://geomag.org.

  1. Ultimate limits to thermally assisted magnetic recording

    International Nuclear Information System (INIS)

    The application of thermal energy to enable recording on extremely high anisotropy magnetic media appears to be a viable means of extending the density of stored information. The central physical issue facing the technology is what gain can be realized in writability along with long-term data stability using imaginable media materials. We reasonably expect the material properties M(T) and Hk(T) to determine this, since a stability metric for media with characteristic magnetization switching unit volume V is MV Hk/2kBT. This matter is controversial owing to still open questions related to thermomagnetic recording with temperature elevation above the Curie point and optimal cooling rates. There are indications that multi-component magnetic media may offer advantages in achieving performance goals. Beyond the physical issues lie engineering matters related to the correct system architecture to yield a practical storage device to meet future customer expectations. Here one must address a detailed means of delivering localized heating to the magnetic medium to perform efficient recording. To date, magnetic recording devices have been highly mechanical systems, so it is natural to inquire how a need for an aggressively heated head-medium interface could impact the evolution of future systems. Eventually elements of thermally assisted recording could be combined with patterned media approaches such as self-organized magnetic arrays to push toward ultimate limits where the thermal instability of bits overtakes engineered media materials. Finally, a practical recording system cannot be realized unless a means of finding, following, and reading the smallest bits with a usable signal-to-noise ratio exists-engineering issues separate from an ability to reliably record those bits. (topical review)

  2. Contribution of the source velocity to the scattering of electromagnetic fields caused by airborne magnetic dipoles

    International Nuclear Information System (INIS)

    The velocity of controlled airborne sources of electromagnetic geophysical surveys plays an additional role in the scattering of the fields by the earth. Therefore, it is necessary to investigate its contribution in the space and time variation of secondary electromagnetic fields. The model of a vertical magnetic dipole moving at a constant speed along a horizontal line in the air and above a homogeneous conductive half-space constitutes a first approach to stress the kinematic aspect and determine the difference between the fields due to an airborne and a static source. The magnetic moment of the source is equal to 104 A m2, its height is 120 m, and the horizontal and vertical separations between it and the receiver are, respectively, equal to 100 and 50 m: these values of the model are typical of towed-bird airborne TDEM surveys. We employed four values for the common velocities of source and receiver (0, 60, 80, and 100 m s−1), four values of the conductivity of the half-space (0.5, 0.1, 0.05, and 0.01 S m−1), and two causal source currents (box with periods of 80 and 10 ms and periodic with frequency values of 12.5 and 100 Hz). The results demonstrate that the relative velocity between source and medium yields a measurable variation compared to the static condition. Therefore, it must be taken into consideration by compensating the discrepancy in measured data employing the respective theoretical result. The results also show that it is necessary to adjust the concepts of time and frequency domain for electromagnetic measurements with traveling sources. (paper)

  3. Theory of Thermal Remagnetization of Permanent Magnets

    OpenAIRE

    Schumann, R.; Jahn, L.

    2001-01-01

    A self-consistent mean-field theory explaining the thermal remagnetization (TR) of polycrystalline permanent magnets is given. The influence of the environment of a grain is treated by an inclusion approximation, relating the field inside the grain to the local field outside by means of an internal demagnetization factor $n$. For the switching fields and the fluctuations of the local fields around the mean field Gaussian distributions of widths $\\sigmas$ and $\\sigmaf$ resp. are assumed. The i...

  4. Locomotion response of airborne, ambulatory and aquatic insects to thermal stimulation using piezoceramic microheaters

    International Nuclear Information System (INIS)

    This paper reports the locomotion response of airborne, ambulatory and aquatic insects to thermal stimulation. A finite element model has been developed to predict the variation of insect–stimulator interface temperature with input power. Piezothermal stimulators have been fabricated from lead zirconate titanate (PZT) using a batch mode micro ultrasonic machining process. Typical sizes range from 200 µm to 3.2 mm. For PZT stimulators, the temperature and thermal efficiency reach the maximum value around the resonance frequency which is typically in the range of 650 kHz to 47 MHz. Experiments have been conducted on green June beetles (GJBs), Madagascar hissing roaches and green diving beetles (GDBs) in order to show the versatility of the proposed technique. The stimulators have been implanted near the antennae of the GJBs and on either side of the thorax of the Madagascar hissing roaches and GDBs, respectively. In all cases, the insects move away from the direction of the actuated stimulator. The left and right turns are statistically similar. Thermal stimulation achieves an overall success rate of 78.7%, 92.8% and 61.6% in GJBs, roaches and GDBs, respectively. On average, thermal stimulation results in an angle turn of about 13.7°–16.2° on GJBs, 30°–45° on the roaches and 30°–50° on GDBs. The corresponding average input power is 360, 330 and 100 mW for GJBs, roach and GDBs, respectively. Scaling limits of the PZT stimulators for operating these stimulators are also discussed.

  5. Airborne Thermal Infrared Multispectral Scanner (TIMS) images over disseminated gold deposits, Osgood Mountains, Humboldt County, Nevada

    Science.gov (United States)

    Krohn, M. Dennis

    1986-01-01

    The U.S. Geological Survey (USGS) acquired airborne Thermal Infrared Multispectral Scanner (TIMS) images over several disseminated gold deposits in northern Nevada in 1983. The aerial surveys were flown to determine whether TIMS data could depict jasperoids (siliceous replacement bodies) associated with the gold deposits. The TIMS data were collected over the Pinson and Getchell Mines in the Osgood Mountains, the Carlin, Maggie Creek, Bootstrap, and other mines in the Tuscarora Mountains, and the Jerritt Canyon Mine in the Independence Mountains. The TIMS data seem to be a useful supplement to conventional geochemical exploration for disseminated gold deposits in the western United States. Siliceous outcrops are readily separable in the TIMS image from other types of host rocks. Different forms of silicification are not readily separable, yet, due to limitations of spatial resolution and spectral dynamic range. Features associated with the disseminated gold deposits, such as the large intrusive bodies and fault structures, are also resolvable on TIMS data. Inclusion of high-resolution thermal inertia data would be a useful supplement to the TIMS data.

  6. Airborne detection of magnetic anomalies associated with soils on the Oak Ridge Reservation, Tennessee

    International Nuclear Information System (INIS)

    Reconnaissance airborne geophysical data acquired over the 35,000-acre Oak Ridge Reservation (ORR), TN, show several magnetic anomalies over undisturbed areas mapped as Copper Ridge Dolomite (CRD). The anomalies of interest are most apparent in magnetic gradient maps where they exceed 0.06 nT/m and in some cases exceed 0.5 nT/m. Anomalies as large as 25nT are seen on maps. Some of the anomalies correlate with known or suspected karst, or with apparent conductivity anomalies calculated from electromagnetic data acquired contemporaneously with the magnetic data. Some of the anomalies have a strong correlation with topographic lows or closed depressions. Surface magnetic data have been acquired over some of these sites and have confirmed the existence of the anomalies. Ground inspections in the vicinity of several of the anomalies has not led to any discoveries of manmade surface materials of sufficient size to generate the observed anomalies. One would expect an anomaly of approximately 1 nT for a pickup truck from 200 ft altitude. Typical residual magnetic anomalies have magnitudes of 5--10 nT, and some are as large as 25nT. The absence of roads or other indications of culture (past or present) near the anomalies and the modeling of anomalies in data acquired with surface instruments indicate that man-made metallic objects are unlikely to be responsible for the anomaly. The authors show that observed anomalies in the CRD can reasonably be associated with thickening of the soil layer. The occurrence of the anomalies in areas where evidences of karstification are seen would follow because sediment deposition would occur in topographic lows. Linear groups of anomalies on the maps may be associated with fracture zones which were eroded more than adjacent rocks and were subsequently covered with a thicker blanket of sediment. This study indicates that airborne magnetic data may be of use in other sites where fracture zones or buried collapse structures are of interest

  7. High spatial resolution imaging of methane and other trace gases with the airborne Hyperspectral Thermal Emission Spectrometer (HyTES)

    OpenAIRE

    G. C. Hulley; Duren, R. M.; F. M. Hopkins; Hook, S. J.; Vance, N.; Guillevic, P.; Johnson, W. R.; Eng, B. T.; Mihaly, J. M.; V. M. JOVANOVIC; Chazanoff, S. L.; Staniszewski, Z. K.; Kuai, Le; Worden, John; Frankenberg, Christian

    2016-01-01

    Currently large uncertainties exist associated with the attribution and quantification of fugitive emissions of criteria pollutants and greenhouse gases such as methane across large regions and key economic sectors. In this study, data from the airborne Hyperspectral Thermal Emission Spectrometer (HyTES) have been used to develop robust and reliable techniques for the detection and wide-area mapping of emission plumes of methane and other atmospheric trace gas species over challenging and div...

  8. Land surface emissivity retrieval from airborne hyperspectral scanner thermal infrared data over urban surfaces

    Science.gov (United States)

    Gao, C. X.; Qian, Y. G.; Wang, N.; Ma, L. L.; Jiang, X. G.

    2015-12-01

    Land surface emissivity (LSE) is a key parameter for characterizing the land surface, and is vital for a wide variety of surface-atmosphere studies. This paper retrieved LSEs of land surfaces over the city of Madrid, Spain from airborne hyperspectral scanner (AHS) thermal infrared data using temperature emissivity separation (TES) method. Six different kinds of urban surfaces: asphalt, bare soil, granite, pavement, shrub and grass pavement, were selected to evaluate the performance of the TES method in urban areas. The results demonstrate that the TES method can be successfully applied to retrieve LSEs in urban area. The six urban surfaces have similar curve shape of emissivity spectra, with the lowest emissivity in band 73, and highest in band 78; the LSE for bare soil varies significantly with spectra, approximately from 0.90 in band 72 to 0.98 in band 78, whereas the LSE for grass has the smallest spectral variation, approximately from 0.965 in band 72 to 0.974 in band 78, and the shrub presents higher LSE than other surfaces in bands 72, 73, 75-77, but a little lower in bands 78 and 79. Furthermore, it is worth noting that band 73 is suitable for discriminating different urban surfaces because large LSE differences exist in this channel for different urban surfaces.

  9. Airborne Thermal Remote Sensing for Estimation of Groundwater Discharge to a River.

    Science.gov (United States)

    Liu, Chuankun; Liu, Jie; Hu, Yue; Wang, Heshun; Zheng, Chunmiao

    2016-05-01

    Traditional methods for studying surface water and groundwater interactions have usually been limited to point measurements, such as geochemical sampling and seepage measurement. A new methodology is presented for quantifying groundwater discharge to a river, by using river surface temperature data obtained from airborne thermal infrared remote sensing technology. The Hot Spot Analysis toolkit in ArcGIS was used to calculate the percentage of groundwater discharge to a river relative to the total flow of the river. This methodology was evaluated in the midstream of the Heihe River in the arid and semiarid northwest China. The results show that the percentage of groundwater discharge relative to the total streamflow was as high as 28%, which is in good agreement with the results from previous geochemical studies. The data analysis methodology used in this study is based on the assumption that the river water is fully mixed except in the areas of extremely low flow velocity, which could lead to underestimation of the amount of groundwater discharge. Despite this limitation, this remote sensing-based approach provides an efficient means of quantifying the surface water and groundwater interactions on a regional scale. PMID:26281027

  10. Thermal resistance of naturally occurring airborne bacterial spores. [Viking spacecraft dry heat decontamination simulation

    Science.gov (United States)

    Puleo, J. R.; Bergstrom, S. L.; Peeler, J. T.; Oxborrow, G. S.

    1978-01-01

    Simulation of a heat process used in the terminal dry-heat decontamination of the Viking spacecraft is reported. Naturally occurring airborne bacterial spores were collected on Teflon ribbons in selected spacecraft assembly areas and subsequently subjected to dry heat. Thermal inactivation experiments were conducted at 105, 111.7, 120, 125, 130, and 135 C with a moisture level of 1.2 mg of water per liter. Heat survivors were recovered at temperatures of 135 C when a 30-h heating cycle was employed. Survivors were recovered from all cycles studied and randomly selected for identification. The naturally occurring spore population was reduced an average of 2.2 to 4.4 log cycles from 105 to 135 C. Heating cycles of 5 and 15 h at temperature were compared with the standard 30-h cycle at 111.7, 120, and 125 C. No significant differences in inactivation (alpha = 0.05) were observed between 111.7 and 120 C. The 30-h cycle differs from the 5- and 15-h cycles at 125 C. Thus, the heating cycle can be reduced if a small fraction (about 0.001 to 0.0001) of very resistant spores can be tolerated.

  11. Extracting Roof Parameters and Heat Bridges Over the City of Oldenburg from Hyperspectral, Thermal, and Airborne Laser Scanning Data

    Science.gov (United States)

    Bannehr, L.; Luhmann, Th.; Piechel, J.; Roelfs, T.; Schmidt, An.

    2011-09-01

    Remote sensing methods are used to obtain different kinds of information about the state of the environment. Within the cooperative research project HiReSens, funded by the German BMBF, a hyperspectral scanner, an airborne laser scanner, a thermal camera, and a RGB-camera are employed on a small aircraft to determine roof material parameters and heat bridges of house tops over the city Oldenburg, Lower Saxony. HiReSens aims to combine various geometrical highly resolved data in order to achieve relevant evidence about the state of the city buildings. Thermal data are used to obtain the energy distribution of single buildings. The use of hyperspectral data yields information about material consistence of roofs. From airborne laser scanning data (ALS) digital surface models are inferred. They build the basis to locate the best orientations for solar panels of the city buildings. The combination of the different data sets offers the opportunity to capitalize synergies between differently working systems. Central goals are the development of tools for the collection of heat bridges by means of thermal data, spectral collection of roofs parameters on basis of hyperspectral data as well as 3D-capture of buildings from airborne lasers scanner data. Collecting, analyzing and merging of the data are not trivial especially not when the resolution and accuracy is aimed in the domain of a few decimetre. The results achieved need to be regarded as preliminary. Further investigations are still required to prove the accuracy in detail.

  12. Temperature and emissivity separation and mineral mapping based on airborne TASI hyperspectral thermal infrared data

    Science.gov (United States)

    Cui, Jing; Yan, Bokun; Dong, Xinfeng; Zhang, Shimin; Zhang, Jingfa; Tian, Feng; Wang, Runsheng

    2015-08-01

    Thermal infrared remote sensing (8-12 μm) (TIR) has great potential for geologic remote sensing studies. TIR has been successfully used for terrestrial and planetary geologic studies to map surface materials. However, the complexity of the physics and the lack of hyperspectral data make the studies under-investigated. A new generation of commercial hyperspectral infrared sensors, known as Thermal Airborne Spectrographic Imager (TASI), was used for image analysis and mineral mapping in this study. In this paper, a combined method integrating normalized emissivity method (NEM), ratio algorithm (RATIO) and maximum-minimum apparent emissivity difference (MMD), being applied in multispectral data, has been modified and used to determine whether this method is suitable for retrieving emissivity from TASI hyperspectral data. MODTRAN 4 has been used for the atmospheric correction. The retrieved emissivity spectra matched well with the field measured spectra except for bands 1, 2, and 32. Quartz, calcite, diopside/hedenbergite, hornblende and microcline have been mapped by the emissivity image. Mineral mapping results agree with the dominant minerals identified by laboratory X-ray powder diffraction and spectroscopic analyses of field samples. Both of the results indicated that the atmospheric correction method and the combined temperature-emissivitiy method are suitable for TASI image. Carbonate skarnization was first found in the study area by the spatial extent of diopside. Chemical analyses of the skarn samples determined that the Au content was 0.32-1.74 g/t, with an average Au content of 0.73 g/t. This information provides an important resource for prospecting for skarn type gold deposits. It is also suggested that TASI is suitable for prospect and deposit scale exploration.

  13. Colloidal Stability and Thermal Stability of Magnetic Fluids

    OpenAIRE

    I.M. Arefyev; T.A. Arefyeva; Yu.B. Kazakov

    2013-01-01

    Colloidal and thermal stabilities of magnetic fluids define the service life of magneto-liquid equipment. The results of the research into colloidal and thermal stabilities of original synthesized magnetic fluids based on kerosene, siloxane fluid and synthetic hydrocarbon oil are presented. The method of carrying agent substitution was used in the research into colloidal stability. The thermal tests were conducted in the research into thermal stability. The conclusions about the prospects of ...

  14. Magnetic field induced augmented thermal conduction phenomenon in magneto nanocolloids

    OpenAIRE

    Katiyar, Ajay; Dhar, Purbarun; Nandi, Tandra; Das, Sarit K

    2015-01-01

    Magnetic field induced drastically augmented thermal conductivity of magneto nanocolloids involving magnetic oxide nanoparticles, viz. Fe2O3, Fe3O4, Nickel oxide (NiO), Cobalt oxide (Co3O4), dispersed in different base fluids (heat transfer oil, kerosene, and ethylene glycol) have been reported. Experiments reveal the augmented thermal transport under the external applied magnetic field, with kerosene based MNCs showing at relatively low magnetic field intensities as compared to the heat tran...

  15. Effectiveness of airborne multispectral thermal data for karst groundwater resources recognition in coastal areas

    Science.gov (United States)

    Pignatti, Stefano; Fusilli, Lorenzo; Palombo, Angelo; Santini, Federico; Pascucci, Simone

    2013-04-01

    Currently the detection, use and management of groundwater in karst regions can be considered one of the most significant procedures for solving water scarcity problems during periods of low rainfall this because groundwater resources from karst aquifers play a key role in the water supply in karst areas worldwide [1]. In many countries of the Mediterranean area, where karst is widespread, groundwater resources are still underexploited, while surface waters are generally preferred [2]. Furthermore, carbonate aquifers constitute a crucial thermal water resource outside of volcanic areas, even if there is no detailed and reliable global assessment of thermal water resources. The composite hydrogeological characteristics of karst, particularly directions and zones of groundwater distribution, are not up till now adequately explained [3]. In view of the abovementioned reasons the present study aims at analyzing the detection capability of high spatial resolution thermal remote sensing of karst water resources in coastal areas in order to get useful information on the karst springs flow and on different characteristics of these environments. To this purpose MIVIS [4, 5] and TASI-600 [6] airborne multispectral thermal imagery (see sensors' characteristics in Table 1) acquired on two coastal areas of the Mediterranean area interested by karst activity, one located in Montenegro and one in Italy, were used. One study area is located in the Kotor Bay, a winding bay on the Adriatic Sea surrounded by high mountains in south-western Montenegro and characterized by many subaerial and submarine coastal springs related to deep karstic channels. The other study area is located in Santa Cesarea (Italy), encompassing coastal cold springs, the main local source of high quality water, and also a noticeable thermal groundwater outflow. The proposed study shows the preliminary results of the two airborne deployments on these areas. The preprocessing of the multispectral thermal imagery

  16. Colloidal Stability and Thermal Stability of Magnetic Fluids

    Directory of Open Access Journals (Sweden)

    I.M. Arefyev

    2013-12-01

    Full Text Available Colloidal and thermal stabilities of magnetic fluids define the service life of magneto-liquid equipment. The results of the research into colloidal and thermal stabilities of original synthesized magnetic fluids based on kerosene, siloxane fluid and synthetic hydrocarbon oil are presented. The method of carrying agent substitution was used in the research into colloidal stability. The thermal tests were conducted in the research into thermal stability. The conclusions about the prospects of synthesized magnetic fluids using in technical equipment are made on the basis of received experimental data.

  17. Magnetic curtailment of the shock-induced thermal instability

    International Nuclear Information System (INIS)

    Efect of magnetic field on the thermal instability is studied in the radiatively cooling region behind an intersteller shock of moderate propagation velocity (approx.10km/sec). It is shown that the presence of intersteller magnetic field of a few micro gauss is very effective in preventing the thermal instability from building-up density concentration. In the absence of magnetic field, the shock-induced thermal instability amplifies preshock density inhomogeneity by more than an order of magnitude. However, in the presence of magnetic field, the amplified density contrast is shown to be only a factor 2. (Author)

  18. Influence of the magnetic field on the thermal condensation

    OpenAIRE

    Hennebelle, P.; Passot, T.

    2007-01-01

    The neutral atomic interstellar medium (HI) is well known to be strongly magnetized. Since HI is a 2-phase medium the questions arise of what is the effect of the magnetic field on a 2-phase medium, how magnetic field affects thermal instability ? Here we summarize analytical and numerical results which have been obtained previously to investigate this question.

  19. An Equivalent Source Method for Modelling the Lithospheric Magnetic Field Using Satellite and Airborne Magnetic Data

    DEFF Research Database (Denmark)

    Kother, Livia Kathleen; Hammer, Magnus Danel; Finlay, Chris;

    data are utilized at all latitudes. Estimates of core and large-scale magnetospheric sources are removed from the satellite measurements using the CHAOS-4 model. Quiet-time and night-side data selection criteria are also employed to minimize the influence of the ionospheric field. The model for the...... regularization (either quadratic or maximum entropy) and Huber weighting. Data error covariance matrices are implemented, accounting for the dependence of data error variances on quasi-dipole latitudes. Results show good consistency with the CM5 and MF7 models for spherical harmonic degrees up to n = 95....... Advantages of the equivalent source method include its local nature and the ease of transforming to spherical harmonics when needed. The method can also be applied in local, high resolution, investigations of the lithospheric magnetic field, for example where suitable aeromagnetic data is available. To...

  20. Extraction of thermal exitance spectra (TIR) from Geoscan MK II scanner imagery - Spectra derived from airborne (mobile) and ground (stationary) imagery compared with spectra from direct exitance spectrometry

    Science.gov (United States)

    Lyon, R. J. P.; Honey, F. R.

    In this work, thermal infrared (TIR) three-band composites were prepared from the raw airborne imagery from the Geoscan Mark II airborne scanner (which has six bands), which exhibited colored areas in the Ludwig Skarn region (Yerington district, Australia), interpreted to show quartz-rich zones and garnet-pyroxene zones. It was found that the same scanner, used in the laboratory to view mineral samples heated to about 45-50 C can produce multiband thermal imagery from which TIR spectra can be extracted, provided that the instrument offsets are corrected by the use of water blackbodies.

  1. Form factors in magnetic scattering of thermal neutrons

    OpenAIRE

    Ballou, Rafik

    2007-01-01

    This lecture addresses the concept of form factor in magnetic scattering of thermal neutrons, analyzing its meaning, discussing its measurement by polarized neutrons and detailing its computation for the ions by the spherical tensor operator formalism.

  2. Thermal Hall Effect of Spin Excitations in a Kagome Magnet.

    Science.gov (United States)

    Hirschberger, Max; Chisnell, Robin; Lee, Young S; Ong, N P

    2015-09-01

    At low temperatures, the thermal conductivity of spin excitations in a magnetic insulator can exceed that of phonons. However, because they are charge neutral, the spin waves are not expected to display a thermal Hall effect. However, in the kagome lattice, theory predicts that the Berry curvature leads to a thermal Hall conductivity κ(xy). Here we report observation of a large κ(xy) in the kagome magnet Cu(1-3, bdc) which orders magnetically at 1.8 K. The observed κ(xy) undergoes a remarkable sign reversal with changes in temperature or magnetic field, associated with sign alternation of the Chern flux between magnon bands. The close correlation between κ(xy) and κ(xx) firmly precludes a phonon origin for the thermal Hall effect. PMID:26382691

  3. Thermal fluctuations of magnetic nanoparticles: Fifty years after Brown

    OpenAIRE

    COFFEY, WILLIAM

    2012-01-01

    The reversal time (superparamagnetic relaxation time) of the magnetization of fine single domain ferromagnetic nanoparticles owing to thermal fluctuations plays a fundamental role in information storage, paleomagnetism, biotechnology, etc. Here a comprehensive tutorial-style review of the achievements of fifty years of development and generalizations of the seminal work of Brown [W.F. Brown, Jr., Phys. Rev., 130, 1677 (1963)] on thermal fluctuations of magnetic nanoparticles is presented. Ana...

  4. Using High-Resolution Hyperspectral and Thermal Airborne Imagery to Assess Physiological Condition in the Context of Wheat Phenotyping

    Directory of Open Access Journals (Sweden)

    Victoria Gonzalez-Dugo

    2015-10-01

    Full Text Available There is a growing need for developing high-throughput tools for crop phenotyping that would increase the rate of genetic improvement. In most cases, the indicators used for this purpose are related with canopy structure (often acquired with RGB cameras and multispectral sensors allowing the calculation of NDVI, but using approaches related with the crop physiology are rare. High-resolution hyperspectral remote sensing imagery provides optical indices related to physiological condition through the quantification of photosynthetic pigment and chlorophyll fluorescence emission. This study demonstrates the use of narrow-band indicators of stress as a potential tool for phenotyping under rainfed conditions using two airborne datasets acquired over a wheat experiment with 150 plots comprising two species and 50 varieties (bread and durum wheat. The flights were performed at the early stem elongation stage and during the milking stage. Physiological measurements made at the time of flights demonstrated that the second flight was made during the terminal stress, known to largely determine final yield under rainfed conditions. The hyperspectral imagery enabled the extraction of thermal, radiance, and reflectance spectra from 260 spectral bands from each plot for the calculation of indices related to photosynthetic pigment absorption in the visible and red-edge regions, the quantification of chlorophyll fluorescence emission, as well as structural indices related to canopy structure. Under the conditions of this study, the structural indices (i.e., NDVI did not show a good performance at predicting yield, probably because of the large effects of terminal water stress. Thermal indices, indices related to chlorophyll fluorescence (calculated using the FLD method, and carotenoids pigment indices (PRI and CAR demonstrated to be better suited for screening complex traits such as crop yield. The study concludes that the indicators derived from high

  5. Airborne gamma-ray and magnetic anomaly signatures of serpentinite in relation to soil geochemistry, northern California

    International Nuclear Information System (INIS)

    Serpentinized ultramafic rocks and associated soils in northern California are characterized by high concentrations of Cr and Ni, low levels of radioelements (K, Th, and U) and high amounts of ferrimagnetic minerals (primarily magnetite). Geophysical attributes over ultramafic rocks, which include airborne gamma-ray and magnetic anomaly data, are quantified and provide indirect measurements on the relative abundance of radioelements and magnetic minerals, respectively. Attributes are defined through a statistical modeling approach and the results are portrayed as probabilities in chart and map form. Two predictive models are presented, including one derived from the aeromagnetic anomaly data and one from a combination of the airborne K, Th and U gamma-ray data. Both models distinguish preferential values within the aerogeophysical data that coincide with mapped and potentially unmapped ultramafic rocks. The magnetic predictive model shows positive probabilities associated with magnetic anomaly highs and, to a lesser degree, anomaly lows, which accurately locate many known ultramafic outcrops, but more interestingly, locate potentially unmapped ultramafic rocks, possible extensions of ultramafic bodies that dip into the shallow subsurface, as well as prospective buried ultramafic rocks. The airborne radiometric model shows positive probabilities in association with anomalously low gamma radiation measurements over ultramafic rock, which is similar to that produced by gabbro, metavolcanic rock, and water bodies. All of these features share the characteristic of being depleted in K, Th and U. Gabbro is the only rock type in the study area that shares similar magnetic properties with the ultramafic rock. The aerogeophysical model results are compared to the distribution of ultramafic outcrops and to Cr, Ni, K, Th and U concentrations and magnetic susceptibility measurements from soil samples. Analysis of the soil data indicates high positive correlation between

  6. Airborne gamma-ray and magnetic anomaly signatures of serpentinite in relation to soil geochemistry, northern California

    Science.gov (United States)

    McCafferty, A.E.; Van Gosen, B. S.

    2009-01-01

    Serpentinized ultramafic rocks and associated soils in northern California are characterized by high concentrations of Cr and Ni, low levels of radioelements (K, Th, and U) and high amounts of ferrimagnetic minerals (primarily magnetite). Geophysical attributes over ultramafic rocks, which include airborne gamma-ray and magnetic anomaly data, are quantified and provide indirect measurements on the relative abundance of radioelements and magnetic minerals, respectively. Attributes are defined through a statistical modeling approach and the results are portrayed as probabilities in chart and map form. Two predictive models are presented, including one derived from the aeromagnetic anomaly data and one from a combination of the airborne K, Th and U gamma-ray data. Both models distinguish preferential values within the aerogeophysical data that coincide with mapped and potentially unmapped ultramafic rocks. The magnetic predictive model shows positive probabilities associated with magnetic anomaly highs and, to a lesser degree, anomaly lows, which accurately locate many known ultramafic outcrops, but more interestingly, locate potentially unmapped ultramafic rocks, possible extensions of ultramafic bodies that dip into the shallow subsurface, as well as prospective buried ultramafic rocks. The airborne radiometric model shows positive probabilities in association with anomalously low gamma radiation measurements over ultramafic rock, which is similar to that produced by gabbro, metavolcanic rock, and water bodies. All of these features share the characteristic of being depleted in K, Th and U. Gabbro is the only rock type in the study area that shares similar magnetic properties with the ultramafic rock. The aerogeophysical model results are compared to the distribution of ultramafic outcrops and to Cr, Ni, K, Th and U concentrations and magnetic susceptibility measurements from soil samples. Analysis of the soil data indicates high positive correlation between

  7. Comparison of magnetocaloric properties from magnetic and thermal measurements

    International Nuclear Information System (INIS)

    The isothermal change of the magnetic entropy of a magnetically ordered material upon application of external magnetic field can be calculated from the temperature and field dependence of the magnetization or of the specific heat. The adiabatic temperature change, i.e., the magnetocaloric effect (MCE) can be measured directly or can be calculated via different methods using the field-dependent specific heat values, or a combination of data obtained via magnetization and thermal measurements. In the present study, magnetic and thermal measurements were carried out on Gd75Y25(TC=232 K) and Gd48Y52(TC=161 K) samples, for applied fields ranging between 0 and 7 T. From both datasets, the magnetic entropy change and MCE values were calculated and compared, in order to assess the mutual reliability of the methods applied. The magnetically or thermally deduced specific heat discontinuities show a reasonable agreement within experimental error. Similar comparison of the calculated magnetic entropy changes reveals that the measured transition temperature and the shape of the curve do not depend on the method selected. It is demonstrated that the choice of an integration constant during entropy calculation has a significant impact on the adiabatic temperature change deduced from the field and temperature dependence of the entropies. For the MCE, a better approximation can be obtained using the magnetically acquired magnetic entropy change and the field-dependent specific heat. The results prove that magnetic measurements carried out in high enough magnetic fields provide reliable information on the isothermal magnetic entropy change and, when combined with field-dependent specific heat measurements, on the magnetocaloric effect as well. copyright 1997 American Institute of Physics

  8. THERMAL MODELS FOR THE FRESCA2 HIGH FIELD MAGNET

    CERN Document Server

    Pietrowicz, S

    2012-01-01

    This report presents the thermal studies and measurement that have been realized, at CEA Saclay, for the thermal design of the Fresca 2 magnet under development in EuCARD HFM program. The first part of the report is dedicated to the numerical study of the thermal behaviour of the Fresca 2 magnet in He II. The second part of the report concerns the experimental measurement on two composite insulation systems made of cyanate ester epoxy mix and tri-functional epoxy (TGPAP-DETDA) with S-glass fiber.

  9. Thermalization of magnetized electrons from black body radiation

    International Nuclear Information System (INIS)

    We describe an interesting mechanism whereby an electron in a strong magnetic field can have both the parallel and perpendicular motions come into thermal equilibrium with black body radiation. The mechanism does not include any collisions with other particles and can overcome the extreme slowing of thermalization of highly magnetized particles at low temperatures. The mechanism depends upon the magnetic field strength having a spatial variation. We provide results from two example cases. This mechanism could affect the temperatures that can be achieved in experiments devoted to trapping antihydrogen

  10. SSC 50mm dipole magnet cryostat thermal measurement results

    International Nuclear Information System (INIS)

    A prototype Superconducting Super Collider (SSC) 50 mm dipole magnet cryostat, DCA323, was instrumented at Fermilab and delivered to the SSC Laboratory for installation into the accelerator systems string test facility. In series with other magnets, the instrumented cryostat will be used to quantify and verify cryostat thermal performance with respect to design requirements. Prior to leaving Fermilab, DCA323 was subjected to magnetic testing at the Magnetic Test Facility (MTF). This presented an opportunity to obtain preliminary thermal performance data under simulated operating conditions. It should be noted that measurements of overall cryostat thermal performance were not possible during the MTF measurements as the magnet test stands are designed for magnetic rather than thermal testing. They are not designed to limit heat inleak to the ends of the cryostat, which has been shown to have a significant effect on overall measured thermal performance. Nonetheless, these measurements do offer insight into the performance of several of the cryostat components and sub-systems

  11. Upgrade of the LHC magnet interconnections thermal shielding

    International Nuclear Information System (INIS)

    The about 1700 interconnections (ICs) between the Large Hadron Collider (LHC) superconducting magnets include thermal shielding at 50-75 K, providing continuity to the thermal shielding of the magnet cryostats to reduce the overall radiation heat loads to the 1.9 K helium bath of the magnets. The IC shield, made of aluminum, is conduction-cooled via a welded bridge to the thermal shield of the adjacent magnets which is actively cooled. TIG welding of these bridges made in the LHC tunnel at installation of the magnets induced a considerable risk of fire hazard due to the proximity of the multi-layer insulation of the magnet shields. A fire incident occurred in one of the machine sectors during machine installation, but fortunately with limited consequences thanks to prompt intervention of the operators. LHC is now undergoing a 2 years technical stop during which all magnet's ICs will have to be opened to consolidate the magnet electrical connections. The IC thermal shields will therefore have to be removed and re-installed after the work is completed. In order to eliminate the risk of fire hazard when re-welding, it has been decided to review the design of the IC shields, by replacing the welded bridges with a mechanical clamping which also preserves its thermal function. An additional advantage of this new solution is the ease in dismantling for maintenance, and eliminating weld-grinding operations at removal needing radioprotection measures because of material activation after long-term operation of the LHC. This paper describes the new design of the IC shields and in particular the theoretical and experimental validation of its thermal performance. Furthermore a status report of the on-going upgrade work in the LHC is given

  12. Thermal investigations of a room temperature magnetic refrigerator

    Energy Technology Data Exchange (ETDEWEB)

    Smaili, Arezki; Chiba, Younes [Ecole Nationale Polytechnique d' Alger (Algeria)], email: arezki.smaili@enp.edu.dz

    2011-07-01

    Magnetic refrigeration is a concept based on the magnetocaloric effect that some materials exhibit when the external magnetic field changes. The aim of this paper is to assess the performance of a numerical model in predicting parameters of an active magnetic regenerator refrigerator. Numerical simulations were conducted to perform a thermal analysis on an active magnetic regenerator refrigerator operating near room temperature with and without applied cooling load. Curves of temperature span, cooling capacity and thermal efficiency as functions of the operating conditions were drawn and are presented in this paper. Results showed that at fixed frequency Ql versus mf has an optimum and COP was increased with cycle frequency values. This study demonstrated that the proposed numerical model could be used to predict parameters of an active magnetic regenerator refrigerator as it provides consistent results.

  13. High spatial resolution imaging of methane and other trace gases with the airborne Hyperspectral Thermal Emission Spectrometer (HyTES)

    Science.gov (United States)

    Hulley, Glynn C.; Duren, Riley M.; Hopkins, Francesca M.; Hook, Simon J.; Vance, Nick; Guillevic, Pierre; Johnson, William R.; Eng, Bjorn T.; Mihaly, Jonathan M.; Jovanovic, Veljko M.; Chazanoff, Seth L.; Staniszewski, Zak K.; Kuai, Le; Worden, John; Frankenberg, Christian; Rivera, Gerardo; Aubrey, Andrew D.; Miller, Charles E.; Malakar, Nabin K.; Sánchez Tomás, Juan M.; Holmes, Kendall T.

    2016-06-01

    Currently large uncertainties exist associated with the attribution and quantification of fugitive emissions of criteria pollutants and greenhouse gases such as methane across large regions and key economic sectors. In this study, data from the airborne Hyperspectral Thermal Emission Spectrometer (HyTES) have been used to develop robust and reliable techniques for the detection and wide-area mapping of emission plumes of methane and other atmospheric trace gas species over challenging and diverse environmental conditions with high spatial resolution that permits direct attribution to sources. HyTES is a pushbroom imaging spectrometer with high spectral resolution (256 bands from 7.5 to 12 µm), wide swath (1-2 km), and high spatial resolution (˜ 2 m at 1 km altitude) that incorporates new thermal infrared (TIR) remote sensing technologies. In this study we introduce a hybrid clutter matched filter (CMF) and plume dilation algorithm applied to HyTES observations to efficiently detect and characterize the spatial structures of individual plumes of CH4, H2S, NH3, NO2, and SO2 emitters. The sensitivity and field of regard of HyTES allows rapid and frequent airborne surveys of large areas including facilities not readily accessible from the surface. The HyTES CMF algorithm produces plume intensity images of methane and other gases from strong emission sources. The combination of high spatial resolution and multi-species imaging capability provides source attribution in complex environments. The CMF-based detection of strong emission sources over large areas is a fast and powerful tool needed to focus on more computationally intensive retrieval algorithms to quantify emissions with error estimates, and is useful for expediting mitigation efforts and addressing critical science questions.

  14. Background Radiance Estimation for Gas Plume Quantification for Airborne Hyperspectral Thermal Imaging

    Directory of Open Access Journals (Sweden)

    Ramzi Idoughi

    2016-01-01

    Full Text Available Hyperspectral imaging in the long-wave infrared (LWIR is a mean that is proving its worth in the characterization of gaseous effluent. Indeed the spectral and spatial resolution of acquisition instruments is steadily decreasing, making the gases characterization increasingly easy in the LWIR domain. The majority of literature algorithms exploit the plume contribution to the radiance corresponding to the difference of radiance between the plume-present and plume-absent pixels. Nevertheless, the off-plume radiance is unobservable using a single image. In this paper, we propose a new method to retrieve trace gas concentration from airborne infrared hyperspectral data. More particularly the outlined method improves the existing background radiance estimation approach to deal with heterogeneous scenes corresponding to industrial scenes. It consists in performing a classification of the scene and then applying a principal components analysis based method to estimate the background radiance on each cluster stemming from the classification. In order to determine the contribution of the classification to the background radiance estimation, we compared the two approaches on synthetic data and Telops Fourier Transform Spectrometer (FTS Imaging Hyper-Cam LW airborne acquisition above ethylene release. We finally show ethylene retrieved concentration map and estimate flow rate of the ethylene release.

  15. Nuclear magnetic resonance of thermally oriented nuclei

    International Nuclear Information System (INIS)

    The more recent developments in the spectroscopy of Nuclear Magnetic Resonance on Oriented Nuclei (NMRON) are reviewed; both theoretical and experimental advances are summarised with applications to On-Line and Off-Line determination of magnetic dipole and electric quadrupole hyperfine parameters. Some emphasis is provided on solid state considerations with indications of where likely enhancements in technique will lead in conventional hyperfine studies. (orig.)

  16. Thermal Casimir Force between Magnetic Materials

    OpenAIRE

    Klimchitskaya, G. L.; Geyer, B.; Mostepanenko, V. M.

    2009-01-01

    We investigate the Casimir pressure between two parallel plates made of magnetic materials at nonzero temperature. It is shown that for real magnetodielectric materials only the magnetic properties of ferromagnets can influence the Casimir pressure. This influence is accomplished through the contribution of the zero-frequency term of the Lifshitz formula. The possibility of the Casimir repulsion through the vacuum gap is analyzed depending on the model used for the description of the dielectr...

  17. Thermally driven vertical displacement of IP quadrupole magnet

    International Nuclear Information System (INIS)

    The IP (interaction point) quadrupole magnets of the TRISTAN MR (main ring), QCS and QC1, at every IP sit on the common support made of steel. When all magnets are cycled through injection, acceleration, flattop and deceleration, the environmental temperature in the tunnel changes periodically following the magnet cycle. The magnet support receives the temperature cycles and the quadrupole on it moves vertically due to the thermal expansion and shrinkage of the support. Its movement was measured with the laser interferometer during the physics experiment. This displacement gives an effect on the closed orbit distortions and requires the orbit correction when it becomes serious. (author)

  18. An algorithm for the estimation of water temperatures from thermal multispectral airborne remotely sensed data

    Science.gov (United States)

    Jaggi, S.; Quattrochi, D.; Baskin, R.

    1992-01-01

    A method for water temperature estimation on the basis of thermal data is presented and tested against NASA's Thermal IR Multispectral Scanner. Using realistic bounds on emissivities, temperature bounds are calculated and refined to estimate a tighter bound on the emissivity of the source. The method is useful only when a realistic set of bounds can be obtained for the emissivities of the data.

  19. Boosting magnetic reconnection by viscosity and thermal conduction

    Science.gov (United States)

    Minoshima, Takashi; Miyoshi, Takahiro; Imada, Shinsuke

    2016-07-01

    Nonlinear evolution of magnetic reconnection is investigated by means of magnetohydrodynamic simulations including uniform resistivity, uniform viscosity, and anisotropic thermal conduction. When viscosity exceeds resistivity (the magnetic Prandtl number P r m > 1 ), the viscous dissipation dominates outflow dynamics and leads to the decrease in the plasma density inside a current sheet. The low-density current sheet supports the excitation of the vortex. The thickness of the vortex is broader than that of the current for P r m > 1 . The broader vortex flow more efficiently carries the upstream magnetic flux toward the reconnection region, and consequently, boosts the reconnection. The reconnection rate increases with viscosity provided that thermal conduction is fast enough to take away the thermal energy increased by the viscous dissipation (the fluid Prandtl number Pr < 1). The result suggests the need to control the Prandtl numbers for the reconnection against the conventional resistive model.

  20. Boosting Magnetic Reconnection by Viscosity and Thermal Conduction

    CERN Document Server

    Minoshima, Takashi; Imada, Shinsuke

    2016-01-01

    Nonlinear evolution of magnetic reconnection is investigated by means of magnetohydrodynamic simulations including uniform resistivity, uniform viscosity, and anisotropic thermal conduction. When viscosity exceeds resistivity (the magnetic Prandtl number Prm > 1), the viscous dissipation dominates outflow dynamics and leads to the decrease in the plasma density inside a current sheet. The low-density current sheet supports the excitation of the vortex. The thickness of the vortex is broader than that of the current for Prm > 1. The broader vortex flow more efficiently carries the upstream magnetic flux toward the reconnection region, and consequently boosts the reconnection. The reconnection rate increases with viscosity provided that thermal conduction is fast enough to take away the thermal energy increased by the viscous dissipation (the fluid Prandtl number Pr < 1). The result suggests the need to control the Prandtl numbers for the reconnection against the conventional resistive model.

  1. Thermal evolution of neutron stars with decaying magnetic fields

    International Nuclear Information System (INIS)

    Rotochemical heating originates in the deviation from beta equilibrium due to spin-down compression, which is closely related to the dipole magnetic field. We numerically calculate the deviation from chemical equilibrium and thermal evolution of neutron stars with decaying magnetic fields. We find that the power-law long term decay of the magnetic field slightly affects the deviation from chemical equilibrium and surface temperature. However, the magnetic decay leads to older neutron stars that could have a different surface temperature with the same magnetic field strength. That is, older neutron stars with a low magnetic field (108 G) could have a lower temperature even with rotochemical heating in operation, which probably explains the lack of other observations on older millisecond pulsars with higher surface temperature, except millisecond pulsar J0437–4715. (paper)

  2. Thermal fluctuations and critical behavior in a magnetized, anisotropic plasma

    Energy Technology Data Exchange (ETDEWEB)

    Hazeltine, R. D.; Mahajan, S. M. [Department of Physics, University of Texas at Austin, Austin, Texas 78712 (United States)

    2013-12-15

    Thermal fluctuations in a magnetized, anisotropic plasma are studied by applying standard methods, based on the Einstein rule, to the known thermodynamic potential of the system. It is found in particular that magnetic fluctuations become critical when the anisotropy p{sub ∥}−p{sub ⊥} changes sign. By examining the critical region, additional insight on the equations of state for near-critical anisotropic plasma is obtained.

  3. Data products of NASA Goddard's LiDAR, hyperspectral, and thermal airborne imager (G-LiHT)

    Science.gov (United States)

    Corp, Lawrence A.; Cook, Bruce D.; McCorkel, Joel; Middleton, Elizabeth M.

    2015-06-01

    Scientists in the Biospheric Sciences Laboratory at NASA's Goddard Space Flight Center have undertaken a unique instrument fusion effort for an airborne package that integrates commercial off the shelf LiDAR, Hyperspectral, and Thermal components. G-LiHT is a compact, lightweight and portable system that can be used on a wide range of airborne platforms to support a number of NASA Earth Science research projects and space-based missions. G-LiHT permits simultaneous and complementary measurements of surface reflectance, vegetation structure, and temperature, which provide an analytical framework for the development of new algorithms for mapping plant species composition, plant functional types, biodiversity, biomass, carbon stocks, and plant growth. G-LiHT and its supporting database are designed to give scientists open access to the data that are needed to understand the relationship between ecosystem form and function and to stimulate the advancement of synergistic algorithms. This system will enhance our ability to design new missions and produce data products related to biodiversity and climate change. G-LiHT has been operational since 2011 and has been used to collect data for a number of NASA and USFS sponsored studies, including NASA's Carbon Monitoring System (CMS) and the American ICESat/GLAS Assessment of Carbon (AMIGA-Carb). These acquisitions target a broad diversity of forest communities and ecoregions across the United States and Mexico. Here, we will discuss the components of G-LiHT, their calibration and performance characteristics, operational implementation, and data processing workflows. We will also provide examples of higher level data products that are currently available.

  4. Field mapping for heat capacity mapping determinations: Ground support for airborne thermal surveys

    Science.gov (United States)

    Lyon, R. J. P.

    1976-01-01

    Thermal models independently derived by Watson, Outcalt, and Rosema were compared using similar input data and found to yield very different results. Each model has a varying degree of sensitivity to any specified parameter. Data collected at Pisgah Crater-Lavic Lake was re-examined to indicate serious discrepancy in results for thermal inertia from Jet Lab Propulsion Laboratory calculations, when made using the same orginal data sets.

  5. Thermal magnetic field noise: Electron optics and decoherence

    Energy Technology Data Exchange (ETDEWEB)

    Uhlemann, Stephan, E-mail: uhlemann@ceos-gmbh.de; Müller, Heiko; Zach, Joachim; Haider, Max.

    2015-04-15

    Thermal magnetic field noise from magnetic and non-magnetic conductive parts close to the electron beam recently has been identified as a reason for decoherence in high-resolution transmission electron microscopy (TEM). Here, we report about new experimental results from measurements for a layered structure of magnetic and non-magnetic materials. For a simplified version of this setup and other situations we derive semi-analytical models in order to predict the strength, bandwidth and spatial correlation of the noise fields. The results of the simulations are finally compared to previous and new experimental data in a quantitative manner. - Highlights: • We report on magnetic field noise of a thermodynamic origin which can cause decoherence in the medium voltage electron microscope (S)TEM. • Previously published and new experimental results are compared to theoretical predictions. • Layered structures of non-magnetic and magnetic materials in electron-optical components are treated theoretically and covered by experiments. • Various ways to calculate the power spectral density of the magnetic noise based on the fluctuation-dissipation theorem are used for the evaluation. • The calculated spatial coherence of magnetic noise in a beam tube is used for the comparison of theoretical predictions and experiments.

  6. Thermal magnetic field noise: Electron optics and decoherence

    International Nuclear Information System (INIS)

    Thermal magnetic field noise from magnetic and non-magnetic conductive parts close to the electron beam recently has been identified as a reason for decoherence in high-resolution transmission electron microscopy (TEM). Here, we report about new experimental results from measurements for a layered structure of magnetic and non-magnetic materials. For a simplified version of this setup and other situations we derive semi-analytical models in order to predict the strength, bandwidth and spatial correlation of the noise fields. The results of the simulations are finally compared to previous and new experimental data in a quantitative manner. - Highlights: • We report on magnetic field noise of a thermodynamic origin which can cause decoherence in the medium voltage electron microscope (S)TEM. • Previously published and new experimental results are compared to theoretical predictions. • Layered structures of non-magnetic and magnetic materials in electron-optical components are treated theoretically and covered by experiments. • Various ways to calculate the power spectral density of the magnetic noise based on the fluctuation-dissipation theorem are used for the evaluation. • The calculated spatial coherence of magnetic noise in a beam tube is used for the comparison of theoretical predictions and experiments

  7. Crustal structure beneath the Paleozoic Parnaíba Basin revealed by airborne gravity and magnetic data, Brazil

    Science.gov (United States)

    de Castroa, David L.; Fuck, Reinhardt A.; Phillips, Jeffrey D. Phillips; Vidotti, Roberta M.; Bezerra, Francisco H.R.; Dantas, Elton L.

    2014-01-01

    The Parnaíba Basin is a large Paleozoic syneclise in northeastern Brazil underlain by Precambrian crystalline basement, which comprises a complex lithostructural and tectonic framework formed during the Neoproterozoic–Eopaleozoic Brasiliano–Pan African orogenic collage. A sag basin up to 3.5 km thick and 1000 km long formed after the collage. The lithologic composition, structure, and role in the basin evolution of the underlying basement are the focus of this study. Airborne gravity and magnetic data were modeled to reveal the general crustal structure underneath the Parnaíba Basin. Results indicate that gravity and magnetic signatures delineate the main boundaries and structural trends of three cratonic areas and surrounding Neoproterozoic fold belts in the basement. Triangular-shaped basement inliers are geophysically defined in the central region of this continental-scale Neoproterozoic convergence zone. A 3-D gravity inversion constrained by seismological data reveals that basement inliers exhibit a 36–40.5 km deep crustal root, with borders defined by a high-density and thinner crust. Forward modeling of gravity and magnetic data indicates that lateral boundaries between crustal units are limited by Brasiliano shear zones, representing lithospheric sutures of the Amazonian and São Francisco Cratons, Tocantins Province and Parnaíba Block. In addition, coincident residual gravity, residual magnetic, and pseudo-gravity lows indicate two complex systems of Eopaleozoic rifts related to the initial phase of the sag deposition, which follow basement trends in several directions.

  8. Electrical and thermal control of magnetic exchange interactions.

    Science.gov (United States)

    Fransson, Jonas; Ren, Jie; Zhu, Jian-Xin

    2014-12-19

    We investigate the far-from-equilibrium nature of magnetic anisotropy and exchange interactions between molecular magnets embedded in a tunnel junction. By mapping to an effective spin model, these magnetic interactions can be divided into three types: isotropic Heisenberg, anisotropic Ising, and anisotropic Dzyaloshinski-Moriya contributions, which are attributed to the background nonequilibrium electronic structures. We further demonstrate that both the magnetic self- and exchange interactions can be controlled either electrically by gating and tuning the voltage bias, or thermally by adjusting the temperature bias. We show that the Heisenberg and Ising interactions scale linearly, while the Dzyaloshinski-Moriya interaction scales quadratically, with the molecule-lead coupling strength. The interactions scale linearly with the effective spin polarizations of the leads and the molecular coherence. Our results pave a way for smart control of magnetic exchange interactions at atomic and molecular levels. PMID:25554904

  9. Integration of airborne optical and thermal imagery for archaeological subsurface structures detection: the Arpi case study (Italy)

    Science.gov (United States)

    Bassani, C.; Cavalli, R. M.; Fasulli, L.; Palombo, A.; Pascucci, S.; Santini, F.; Pignatti, S.

    2009-04-01

    archaeological area (southern Italy). We identify, for the selected sites, three main land cover overlying the buried structures: (a) photosynthetic (i.e. green low vegetation), (b) non-photosynthetic vegetation (i.e. yellow, dry low vegetation), and (c) dry bare soil. Afterwards, we analyse the spectral regions showing an inherent potential for the archaeological detection as a function of the land cover characteristics. The classified land cover units have been used in a spectral mixture analysis to assess the land cover fractional abundance surfacing the buried structures (i.e. mark-background system). The classification and unmixing results for the CASI, MIVIS and ATM remote sensing data processing showed a good accordance both in the land cover units and in the subsurface structures identification. The integrated analysis of the unmixing results for the three sensors allowed us to establish that for the land cover characterized by green and dry vegetation (occurrence higher than 75%), the visible and near infrared (VNIR) spectral regions better enhance the buried man-made structures. In particular, if the structures are covered by more than 75% of vegetation the two most promising wavelengths for their detection are the chlorophyll peak at 0.56 m (Visible region) and the red edge region (0.67 to 0.72 m; NIR region). This result confirms that the variation induced by the subsurface structures (e.g., stone walls, tile concentrations, pavements near the surface, road networks) to the natural vegetation growth and/or colour (i.e., for different stress factors) is primarily detectable by the chlorophyll peak and the red edge region applied for the vegetation stress detection. Whereas, if dry soils cover the structures (occurrence higher than 75%), both the VNIR and thermal infrared (TIR) regions are suitable to detect the subsurface structures. This work demonstrates that airborne reflectances and emissivities data, even though at different spatial/spectral resolutions and

  10. Circuit, Thermal and Cost Characteristics of Impulse Magnetizing Circuits

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This paper describes the development of circuit, thermal and cost model for a capacitor discharge impulse megnetizer and compares simulations to measurements from an actual system. We used a cost structure consisting of five major subsystems for cost modeling. Especially, we estimated the potential for cost reductions impulse magnetizer as a function of time using the learning curve.

  11. Magnetic properties related to thermal treatment of pyrite

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Detailed rock magnetic experiments were conducted on high-purity natural crystalline pyrite and its products of thermal treatments in both argon and air atmospheres. In argon atmosphere (reducing environment), the pyrite is altered by heating to magnetite and pyrrhotite; the latter is stable in argon atmosphere, and has coercive force and coercivity of remanence of ~20 and ~30 mT, respectively. Whereas in air, the pyrite is ultimately oxidized to hematite. First order reversal curve (FORC) diagram of the end product shows that the remanence coercivity of hematite is up to ~1400 mT. The corresponding thermal transformation process of pyrite in air can be simply summarized as pyrite→ pyrrhotite→magnetite→hematite. These results are helpful for understanding of sedimentary magnetism, secondary chemical remanence and meteorolite magnetic properties.

  12. Characteristics of thermally assisted magnetic recording in granular perpendicular media

    International Nuclear Information System (INIS)

    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

  13. Very high resolution airborne imagery for characterising spatial and temporal thermal patterns of braided rivers

    Science.gov (United States)

    Wawrzyniak, V.; Piégay, H.; Allemand, P.; Grandjean, P.

    2011-12-01

    At the catchment scale water temperature is influenced by geographical factors, but at the reach scale superficial and groundwater hydrology and channel geometry strongly affect thermal patterns. During the last 30 years, studies have been pointed out the significance and complexity of water exchanges between the channel and the hyporheic and phreatic zones. These surface-subsurface water exchanges influence water temperature patterns. Braided rivers present particular thermal conditions with very high spatial water temperature variability. This high thermal variability is difficult to comprehend using only in situ measurements and so thermal infrared (TIR) remote sensing is particularly suited to assessing the thermal patterns associated with these rivers. The aims of this study are to evaluate temperature patterns of nine braided reaches at very high spatial resolution (~20 cm) and to link temperature and water-body types. We hypothesized that river type has an influence of the spatial patterns of water temperature and that the patterns change through the day. All reaches are located in France, in the Rhône catchment. The nine reaches were selected based on high aquatic habitat diversities and are located in three regional areas: the massif des Écrins, the Rhône valley, and south Alps. They are about 1 km long. We have three distinct temporal approaches. The first one is a multi-site approach which proposes one survey of each site during summers 2010 or 2011. Three reaches were selected for the second phase (a multi-annual analysis and were therefore imaged both in summers 2010 and 2011. The last phase is an intra-day survey of two reaches with several flights at different times of day. This presentation focuses on the last approach with two reaches of the Drôme and Drac Noir rivers. To observe the evolution of the thermal patterns of these two reaches through the day, four flights within a day were realized during summer 2011 for both sites. The Drôme reach

  14. Modelling climate change effects on a Dutch coastal groundwater system using airborne Electro Magnetic measurements

    OpenAIRE

    M. Faneca Sànchez; J. L. Gunnink; E. S. van Baaren; Oude Essink, G.H.P.; B. Siemon; E. Auken; W. Elderhorst; de Louw, P.G.B.

    2012-01-01

    The forecast of climate change effects on the groundwater system in coastal areas is of key importance for policy makers. The Dutch water system has been deeply studied because of its complex system of low-lying areas, dunes, land won to the sea and dikes, but nowadays large efforts are still being done to find out the best techniques to describe complex fresh-brackish-saline groundwater dynamic systems. In this article, we describe a methodology consisting of high-resolution airborne Electro...

  15. Insights into the Structure and Surface Geology of Isla Socorro, Mexico, from Airborne Magnetic and Gamma-Ray Surveys

    Science.gov (United States)

    Paoletti, V.; Gruber, S.; Varley, N.; D'Antonio, M.; Supper, R.; Motschka, K.

    2016-05-01

    The island of Socorro is located in the eastern Pacific Ocean, 650 km off the coast of Mexico. It is a rare example of an oceanic volcanic island whose above sea level volume is made up mostly of peralkaline trachytes and rhyolites, with subordinate mafic rocks. Subaerial volcanism started several hundred thousand years ago and continues until recent times. We present an investigation of surface and subsurface geology of the island, based on the first detailed extensive geophysical survey on the island. Acquired airborne magnetic and gamma-ray data were compared to existing geological information and supplemented with field investigations and satellite imagery. Magnetic data show a wide minimum in the central part of the island, possibly connected to a high-temperature zone in the deeper central portion of the volcano, likely to be due to a still hot magma body. The data also depict two parallel edges possibly suggesting the existence of a nested caldera. Analysis on upward continued magnetic data by recent imaging techniques highlighted two deep sources located around 5 km b.s.l., interpreted as feeding structures that are now filled with crystalline rocks. Gamma-ray data have been interpreted through integration with the geological survey results. Several previously known volcanic deposits have been identified based on radioelement distribution, and others have been redefined based on field evidence. A new succession of volcanic members is proposed, to be verified through more detailed geological mapping, geochemical analyses of rock samples and radiometric dating.

  16. Effect of poly (ethylene glycol) coating on the magnetic and thermal properties of biocompatible magnetic liquids

    International Nuclear Information System (INIS)

    The aim of this study was to investigate the influence of poly(ethylene glycol) surface-active coating on the magnetic and thermal properties of biocompatible magnetic liquids. The data were analyzed using the high-temperature approximation model taking into account polydispersity of a system. Heating ability of the PEG-stabilized magnetic fluids was determined by the calorimetric measurement of specific absorption rate (SAR) at a frequency of 750 kHz and a magnetic field of 0-2 kA/m. MF-Oleate/PEG heating properties were found to be comparable to the ones of MF-Oleate. The PEG shell thus does not seem to effect the thermal characteristics and SAR values and might make the magnetic fluid useful for application in hyperthermia treatment.

  17. Fabrication and characterization of thermally actuated micromechanical resonators for airborne particle mass sensing: II. Device fabrication and characterization

    International Nuclear Information System (INIS)

    This paper, the second of two parts, presents extensive measurement and characterization results on fabricated thermally actuated single-crystal silicon MEMS resonators analyzed in part I. The resonators have been fabricated using a single mask process on SOI substrates. Resonant frequencies in a few hundreds of kHz to a few MHz and equivalent motional conductances as high as 102 mA V−1 have been measured for the fabricated resonators. The measurement results have been compared to the resonator characteristics predicted by the model developed in part I showing a good agreement between the two. Despite the relatively low frequencies, high quality factors (Q) of the order of a few thousand have been measured for the resonators under atmospheric pressure. The mass sensitivities of some of the resonators were characterized by embedding them in a custom-made test setup and deposition of artificially generated aerosol particles with known size and composition. The resulting measured mass sensitivities are of the order of tens to hundreds of Hz ng−1 and are in agreement with the expected values based on the resonator's physical dimensions. Finally, measurement of mass density of arbitrary airborne particles in the surrounding lab environment has been demonstrated

  18. Airborne Thermal Imagery to Detect the Seasonal Evolution of Crop Water Status in Peach, Nectarine and Saturn Peach Orchards

    Directory of Open Access Journals (Sweden)

    Joaquim Bellvert

    2016-01-01

    Full Text Available In the current scenario of worldwide limited water supplies, conserving water is a major concern in agricultural areas. Characterizing within-orchard spatial heterogeneity in water requirements would assist in improving irrigation water use efficiency and conserve water. The crop water stress index (CWSI has been successfully used as a crop water status indicator in several fruit tree species. In this study, the CWSI was developed in three Prunus persica L. cultivars at different phenological stages of the 2012 to 2014 growing seasons, using canopy temperature measurements of well-watered trees. The CWSI was then remotely estimated using high-resolution thermal imagery acquired from an airborne platform and related to leaf water potential (ѰL throughout the season. The feasibility of mapping within-orchard spatial variability of ѰL from thermal imagery was also explored. Results indicated that CWSI can be calculated using a common non-water-stressed baseline (NWSB, upper and lower limits for the entire growing season and for the three studied cultivars. Nevertheless, a phenological effect was detected in the CWSI vs. ѰL relationships. For a specific given CWSI value, ѰL was more negative as the crop developed. This different seasonal response followed the same trend for the three studied cultivars. The approach presented in this study demonstrated that CWSI is a feasible method to assess the spatial variability of tree water status in heterogeneous orchards, and to derive ѰL maps throughout a complete growing season. A sensitivity analysis of varying pixel size showed that a pixel size of 0.8 m or less was needed for precise ѰL mapping of peach and nectarine orchards with a tree crown area between 3.0 to 5.0 m2.

  19. Dynamic compact model of thermally assisted switching magnetic tunnel junctions

    Science.gov (United States)

    El Baraji, M.; Javerliac, V.; Guo, W.; Prenat, G.; Dieny, B.

    2009-12-01

    The general purpose of spin electronics is to take advantage of the electron's spin in addition to its electrical charge to build innovative electronic devices. These devices combine magnetic materials which are used as spin polarizer or analyzer together with semiconductors or insulators, resulting in innovative hybrid CMOS/magnetic (Complementary MOS) architectures. In particular, magnetic tunnel junctions (MTJs) can be used for the design of magnetic random access memories [S. Tehrani, Proc. IEEE 91, 703 (2003)], magnetic field programmable gate arrays [Y. Guillement, International Journal of Reconfigurable Computing, 2008], low-power application specific integrated circuits [S. Matsunaga, Appl. Phys. Express 1, 091301 (2008)], and rf oscillators. The thermally assisted switching (TAS) technology requires heating the MTJ before writing it by means of an external field. It reduces the overall power consumption, solves the data writing selectivity issues, and improves the thermal stability of the written information for high density applications. The design of hybrid architectures requires a MTJ compact model, which can be used in standard electrical simulators of the industry. As a result, complete simulations of CMOS/MTJ hybrid circuits can be performed before experimental realization and testing. This article presents a highly accurate model of the MTJ based on the TAS technology. It is compatible with the Spectre electrical simulator of Cadence design suite.

  20. Thermal ensemble of string gas in a magnetic field

    OpenAIRE

    Russo, J. G.

    1994-01-01

    We study the thermal ensemble of a gas of free strings in presence of a magnetic field. We find that the thermodynamical partition function diverges when the magnetic field exceeds some critical value $B_{\\rm cr}$, which depends on the temperature. We argue that there is a first-order phase transition with a large latent heat. At the critical value an infinite number of states -all states in a Regge trajectory- seem to become massless, which may be an indication of recuperation of spontaneous...

  1. G-LiHT: Goddard's LiDAR, Hyperspectral and Thermal Airborne Imager

    Science.gov (United States)

    Cook, Bruce; Corp, Lawrence; Nelson, Ross; Morton, Douglas; Ranson, Kenneth J.; Masek, Jeffrey; Middleton, Elizabeth

    2012-01-01

    Scientists at NASA's Goddard Space Flight Center have developed an ultra-portable, low-cost, multi-sensor remote sensing system for studying the form and function of terrestrial ecosystems. G-LiHT integrates two LIDARs, a 905 nanometer single beam profiler and 1550 nm scanner, with a narrowband (1.5 nanometers) VNIR imaging spectrometer and a broadband (8-14 micrometers) thermal imager. The small footprint (approximately 12 centimeters) LIDAR data and approximately 1 meter ground resolution imagery are advantageous for high resolution applications such as the delineation of canopy crowns, characterization of canopy gaps, and the identification of sparse, low-stature vegetation, which is difficult to detect from space-based instruments and large-footprint LiDAR. The hyperspectral and thermal imagery can be used to characterize species composition, variations in biophysical variables (e.g., photosynthetic pigments), surface temperature, and responses to environmental stressors (e.g., heat, moisture loss). Additionally, the combination of LIDAR optical, and thermal data from G-LiHT is being used to assess forest health by sensing differences in foliage density, photosynthetic pigments, and transpiration. Low operating costs (approximately $1 ha) have allowed us to evaluate seasonal differences in LiDAR, passive optical and thermal data, which provides insight into year-round observations from space. Canopy characteristics and tree allometry (e.g., crown height:width, canopy:ground reflectance) derived from G-LiHT data are being used to generate realistic scenes for radiative transfer models, which in turn are being used to improve instrument design and ensure continuity between LiDAR instruments. G-LiHT has been installed and tested in aircraft with fuselage viewports and in a custom wing-mounted pod that allows G-LiHT to be flown on any Cessna 206, a common aircraft in use throughout the world. G-LiHT is currently being used for forest biomass and growth estimation

  2. Mass production of magnetic nickel nanoparticle in thermal plasma reactor

    Energy Technology Data Exchange (ETDEWEB)

    Kanhe, Nilesh S.; Nawale, Ashok B.; Bhoraskar, S. V.; Mathe, V. L., E-mail: vlmathe@physics.unipune.ac.in [Department of Physics, University of Pune, Pune- 411007 (India); Das, A. K. [Laser and Plasma Technology Division, Bhabha Atomic Research Center, Trombay, Mumbai- 400085 (India)

    2014-04-24

    We report the mass production of Ni metal nanoparticles using dc transferred arc thermal plasma reactor by homogeneous gas phase condensation process. To increase the evaporation rate and purity of Ni nanoparticles small amount of hydrogen added along with argon in the plasma. Crystal structure analysis was done by using X-ray diffraction technique. The morphology of as synthesized nanoparticles was carried out using FESEM images. The magnetic properties were measured by using vibrating sample magnetometer at room temperature.

  3. Magnetic and optical properties of airborne dust and settling rates at the Phoenix landing site

    DEFF Research Database (Denmark)

    Drube, Line; Leer, Kristoffer; Walter, Goetz;

    2010-01-01

    The Magnetic Properties Experiment (referred to as iSweep or Caltarget) onboard the Phoenix lander was executed in the arctic region of Mars during the mission's 152 sols lifetime. The iSweep experiment involved periodic multispectral imaging of a series of permanent ring magnets. It was designed...... on the precursor Sweep Magnet Experiment onboard the Mars Exploration Rovers near Mars' equator, and also this dust is found to be brighter than both surface soil near the lander and soil in the region surrounding the lander. As most other dust and soils on Mars, the Phoenix dust lacks strong...

  4. Mercury's thermal history and the generation of its magnetic field

    International Nuclear Information System (INIS)

    Thermal history of Mercury's interior is examined using the model of Stevenson et al. (1983), extended to include the effects of tidal heating in Mercury's solid inner core. The implications of Mercury's thermal history for the source of the planet's magnetic field are discussed. It is shown that the major results of this model are similar to the results obtained with the Stevenson et al. model, except for the addition of inner-core tidal dissipation. It is concluded that the extended model properly characterizes Mercury's internal structure and thermal history, and that the criteria for dynamo generation are not properly satisfied. Alternative explanations, including the possibility of a weak thermoelectric dynamo, are examined

  5. Thermal Instability and Magnetic Pressure in the Turbulent Interstellar Medium

    CERN Document Server

    Vázquez-Semadeni, E; Passot, T; Sánchez-Salcedo, F J; Vazquez-Semadeni, Enrique; Gazol, Adriana; Passot, Thierry; Sanchez-Salcedo, Javier

    2003-01-01

    We review recent results on the nonlinear development of thermal instability (TI) in the context of the turbulent atomic interstellar medium (ISM). First, we discuss the growth of entropy perturbations in isolation, as a function of the ratio \\eta of the cooling time to the dynamical crossing time. For \\eta~ 0.3) and occurs at scales with \\eta>1. We then consider the behavior of magnetic pressure in turbulent regimes. We propose that the reported lack of correlation between the magnetic pressure and the density is a consequence of the different scaling of the magnetic pressure with density for the slow and fast modes of nonlinear MHD waves. This implies that magnetic ``pressure'' is not a suitable candidate for supplementing thermal pressure in the presence of TI, and that polytropic descriptions of it are probably not adequate in the fully turbulent regime. Finally, we consider TI in a turbulent ISM-like medium. We find that the flow does not exhibit sharp phase transitions, as would be expected in classical...

  6. Comparison of Magnetic Anomalies of Lithospheric Origin Measured by Satellite and Airborne Magnetometers over Western Canada

    Science.gov (United States)

    Langel, R. A.; Coles, R. L.; Mayhew, M. A.

    1979-01-01

    Crustal magnetic anomaly data from the OGO 2, 4 and 6 (Pogo) satellites are compared with upward-continued aeromagnetic data between 50 deg -85 deg N latitude and 220 deg - 260 deg E longitude. Agreement is good both in anomaly location and in amplitude, giving confidence that it is possible to proceed with the derivation and interpretation of satellite anomaly maps in all parts of the globe. The data contain a magnetic high over the Alpha ridge suggesting continental composition and a magnetic low over the southern Canada basin and northern Canadian Arctic islands (Sverdrup basin). The low in the Sverdrup basin corresponds to a region of high heat flow, suggesting a shallow Curie isotherm. A ridge of high field, with two distinct peaks in amplitude, is found over the northern portion of the platform deposits and a relative high is located in the central portion of the Churchill province. No features are present to indicate a magnetic boundary between Slave and Bear provinces, but a trend change is evident between Slave and Churchill provinces. South of 60 deg latitude a broad magnetic low is located over very thick (40-50 km) crust, interpreted to be a region of low magnetization.

  7. Exposure to airborne isocyanates and other thermal degradation products at polyurethane-processing workplaces.

    Science.gov (United States)

    Henriks-Eckerman, Maj-Len; Välimaa, Jarmo; Rosenberg, Christina; Peltonen, Kimmo; Engström, Kerstin

    2002-10-01

    The thermal degradation products of polyurethanes (PURs) and exposure to isocyanates were studied by stationary and personal measurements in five different occupational environments. Isocyanates were collected on glass fibre filters impregnated with 1-(2-methoxyphenyl)piperazine (2MP) and in impingers containing n-dibutylamine (DBA) in toluene. connected to a glass fibre postfilter. The derivatives formed were analysed by liquid chromatography: 2MP derivatives with UV and electrochemical detection and DBA derivatives with mass spectrometric detection. The release of aldehydes and other volatile organic compounds into the air was also studied. In a comparison of the two sampling methods, the 2MP method yielded about 20% lower concentrations for 4,4'-methylenediphenyl diisocyanate (MDI) than did the DBA method. In car repair shops, the median concentration of diisocyanates (given as NCO groups) in the breathing zone was 1.1 microg NCO m(-3) during grinding and 0.3 microg NCO m(-3) during welding, with highest concentrations of 1.7 and 16 pg NCO m(-3), respectively. High concentrations of MDI, up to 25 and 19 microg NCO m(-3), respectively, were also measured in the breathing zone during welding of district heating pipes and turning of a PUR-coated metal cylinder. During installation of PUR-coated floor covering, small amounts of aliphatic diisocyanates were detected in the air. A small-molecular monoisocyanate, methyl isocyanate, and isocyanic acid were detected only during welding and turning operations. The diisocyanate concentrations were in general higher near the emission source than in the workers' breathing zone. A sampling strategy to evaluate the risk of exposure to isocyanates is presented. PMID:12400920

  8. Airborne thermal degradation products of polyurethene coatings in car repair shops.

    Science.gov (United States)

    Karlsson, D; Spanne, M; Dalene, M; Skarping, G

    2000-10-01

    A methodology for workplace air monitoring of aromatic and aliphatic, mono- and polyisocyanates by derivatisation with di-n-butylamine (DBA) is presented. Air sampling was performed using midget impinger flasks containing 10 ml of 0.01 mol l(-1) DBA in toluene and a glass-fibre filter in series after the impinger flask, thereby providing the possibility of collecting and derivatising isocyanates in both the gas and particle phases. Quantification was made by LC-MS, monitoring the molecular ions [MH]+. Air samples taken with this method in car repair shops showed that many different isocyanates are formed during thermal decomposition of polyurethane (PUR) coatings. In addition to isocyanates such as hexamethylene (HDI), isophorone (IPDI), toluene (TDI) and methylenediphenyl diisocyanate (MDI), monoisocyanates such as methyl (MIC), ethyl (EIC), propyl (PIC), butyl (BIC) and phenyl isocyanate (PhI) were found. In many air samples the aliphatic monoisocyanates dominated. During cutting and welding operations, the highest levels of isocyanates were observed. In a single air sample from a welding operation in a car repair shop, the highest concentrations found were: MIC, 290; EIC, 60; PIC, 20; BIC, 9; PhI, 27; HDI, 105; IPDI, 39; MDI, 4; and 2,4-TDI and 2,6-TDI 140 microg m(-3). Monitoring the particle size distribution and concentration during grinding, welding and cutting operations showed that ultrafine particles (volatility were mainly found in the particle phase, but isocyanates with a relatively high volatility such as TDI, were found in both the particle and gas phases. PMID:11254051

  9. Thermal stability of a thin disk with magnetically driven winds

    International Nuclear Information System (INIS)

    The absence of thermal instability in the high/soft state of black hole X-ray binaries, in disagreement with the standard thin disk theory, has been a long-standing riddle for theoretical astronomers. We have tried to resolve this question by studying the thermal stability of a thin disk with magnetically driven winds in the M-dot −Σ plane. It is found that disk winds can greatly decrease the disk temperature and thus help the disk become more stable at a given accretion rate. The critical accretion rate, M-dot crit, corresponding to the thermal instability threshold, is significantly increased in the presence of disk winds. For α = 0.01 and B φ = 10B p, the disk is quite stable even for a very weak initial poloidal magnetic field [βp,0∼2000,βp=(Pgas+Prad)/(Bp2/8π)]. However, when B φ = B p or B φ = 0.1B p, a somewhat stronger (but still weak) field (βp, 0 ∼ 200 or βp, 0 ∼ 20) is required to make the disk stable. Nevertheless, despite the great increase of M-dot crit, the luminosity threshold, corresponding to instability, remains almost constant or decreases slowly with increasing M-dot crit due to decreased gas temperature. The advection and diffusion timescales of the large-scale magnetic field threading the disk are also investigated in this work. We find that the advection timescale can be smaller than the diffusion timescale in a disk with winds, because the disk winds take away most of the gravitational energy released in the disk, resulting in the decrease of the magnetic diffusivity η and the increase of the diffusion timescale.

  10. Application of the factor Kriging analysis in interpretation of airborne magnetic data

    International Nuclear Information System (INIS)

    A factor Kriging analysis which combine the idea of Kriging analysis with principle component analysis is described. In order to give up the magnetic spectrum its covariance function is derived by the fourier inverse transform of 2-dimention. From the analysis of the structure for the variogramm the various ranges are obtained. After principle component analysis the variable split into two principle component corresponding to different frequancy intervals. It shows that every range is the double depth of burial of the corresponding geological structure. An example of initial applying this method for magnetic data obtained from the Damao Banner in The Nei Monggol Aotonomous Region is presented

  11. Lanthanide phosphonates: Synthesis, thermal stability and magnetic characterization

    Energy Technology Data Exchange (ETDEWEB)

    Amghouz, Z., E-mail: amghouz.uo@uniovi.es [Departamentos de Quimica Fisica y Analitica y Quimica Organica e Inorganica, Universidad de Oviedo - CINN, 33006 Oviedo (Spain); Garcia, J.R.; Garcia-Granda, S. [Departamentos de Quimica Fisica y Analitica y Quimica Organica e Inorganica, Universidad de Oviedo - CINN, 33006 Oviedo (Spain); Clearfield, A. [Department of Chemistry, Texas A and M University, College Station, TX 77842-3012 (United States); Rodriguez Fernandez, J.; Pedro, I. de [CITIMAC, Facultad de Ciencias, Universidad de Cantabria, 39005 Santander (Spain); Blanco, J.A. [Departamento de Fisica, Universidad de Oviedo, 33007 Oviedo (Spain)

    2012-09-25

    Highlights: Black-Right-Pointing-Pointer Report of the complete series of lanthanide 1,4-phenylbis(phosphonate). Black-Right-Pointing-Pointer Synthesis under conventional hydrothermal synthesis or microwave-assisted hydrothermal synthesis. Black-Right-Pointing-Pointer Cation size is the key factor for the structural and particles size variations. Black-Right-Pointing-Pointer Thermal behaviour is characterized by unusual very high thermal stability. - Abstract: Series of novel organic-inorganic hybrids materials based on trivalent lanthanides (Ln = Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) and 1,4-phenylbis(phosphonate) obtained under hydrothermal conditions either by oven heat or microwave irradiation. The anhydrous compounds containing La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, and Ho, are isostructural. However, the compounds based on Y, Er, Tm, Yb, and Lu are hydrated and their structures have not yet been solved. The series of compounds are characterized by PXRD, TEM, SEM-EDX and thermal analyses (TG-MS and DSC). TEM study show a variable particles size with a minimum mean-particle size of ca. 30 nm. These compounds exhibit unusual very high thermal stability. The size of particles and the thermal stability are depending on lanthanide(III) cation features. All the investigated materials show paramagnetic behaviour. The magnetic susceptibility data follow a Curie-Weiss laws with paramagnetic effective moments in good agreement with those expected for Ln{sup 3+} free ions.

  12. Measurement of thermal properties of magnetic nanoparticles using infrared thermal microscopy

    DEFF Research Database (Denmark)

    Kim, Jae Young; Chang, Ki Soo; Kook, Myung Ho;

    2013-01-01

    Magnetic nanoparticles (MNPs) are considered promising for biomedical applications such as hyperthermia treatment and disease diagnosis owing to their distinctive thermal properties. For these applications, it is essential to screen the temperature distribution in the targeted disease site. This...... study aimed to investigate and observe the thermal properties of a small amount of MNPs used as highly sensitive biomarkers for disease diagnosis by microthermography. Toward this end, we used polyacrylamide and agarose phantoms containing a small amount of MNPs (30 mg Fe-1). In phantoms, the increasing...

  13. Magnetization strucrure of thermal vent on island arc from vector magnetic anomlies using AUV

    Science.gov (United States)

    Isezaki, N.; Matsuo, J.; Sayanagi, K.

    2012-04-01

    The geomagnetic anomaly measured by a scalar magnetometer,such as a proton precession magnetometer cannot be defined its direction, then it does not satisfy the Laplace's equation. Therefore physical formula describing the relation between magnetic field and magnetization cannot be established.Because the difference between results obtained from scalar data and from vector data is very significant, we must use vector magnetic field data for magnetization analyses to get the more reliable and exact solutions. The development program of fundamental tools for exploration of deep seabed resources started with the financial support of the Ministry of Education, Culture, Sports, Science & Technology (MEXT) in 2008 and will end in 2012. In this project, we are developing magnetic exploration tools for seabed resources using AUV (Autonomous Underwater Vehicle) and other deep-towed vehicles to measure not the scalar magnetic field but the vector magnetic field in order to estimate magnetization structure below the sea-floor exactly and precisely. We conducted AUV magnetic survey in 2010 at the thermal area called Hakurei deposit in the Bayonnaise submarine caldera at the southern end of Izu island arc, about 400km south of Tokyo. We analyzed the observed vector magnetic fields to get the vector magnetic anomaly Fields using the method of Isezaki(1984). We inverted these vector magnetic anomaly fields to magnetization structure. CONCLUSIONS 1.The scalar magnetic field TIA (Total Intensity Anomaly) has no physical formula describing the relation between M (Magnetization) and TIA because TIA does not satisfy the Laplace's equation. Then it is impossible to estimate M from TIA. 2.Anlyses of M using TIA have been done so far under assumption TIA=PTA (Projected Total Anomay on MF (Main Geomagnetic Field)), however, which caused the analysis error due to ɛT= TIA - PTA . 3.We succeeded to measure the vector magnetic anomaly fields using AUV despite the severe magnetic noises

  14. Optimal electron, phonon, and magnetic characteristics for low energy thermally induced magnetization switching

    Energy Technology Data Exchange (ETDEWEB)

    Atxitia, U., E-mail: Unai.Atxitia@uni-konstanz.de [Fachbereich Physik, Universität Konstanz, D-78457 Konstanz (Germany); Zukunftskolleg, Universität Konstanz, D-78457 Konstanz (Germany); Ostler, T. A., E-mail: t.ostler@exeter.ac.uk [Department of Physics, University of York, York YO105DD (United Kingdom); College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, Devon EX4 4SB (United Kingdom); Chantrell, R. W. [Department of Physics, University of York, York YO105DD (United Kingdom); Chubykalo-Fesenko, O. [Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049 Madrid (Spain)

    2015-11-09

    Using large-scale computer simulations, we thoroughly study the minimum energy required to thermally induced magnetization switching (TIMS) after the application of a femtosecond heat pulse in transition metal-rare earth ferrimagnetic alloys. We find that for an energy efficient TIMS, a low ferrimagnetic net magnetization with a strong temperature dependence is the relevant factor for the magnetic system. For the lattice and electron systems, the key physics for efficient TIMS is a large electron-phonon relaxation time. Importantly, we show that as the cooling time of the heated electrons is increased, the minimum power required to produce TIMS can be reduced by an order of magnitude. Our results show the way to low power TIMS by appropriate engineering of magnetic heterostructures.

  15. Magnetism and thermal evolution of the terrestrial planets

    International Nuclear Information System (INIS)

    The absence in the cases of Venus and Mars of the substantial intrinsic magnetic fields of the earth and Mercury is considered, in light of thermal history calculations which suggest that, while the cores of Mercury and the earth are continuing to freeze, the cores of Venus and Mars may still be completely liquid. It is noted that completely fluid cores, lacking intrinsic heat sources, are not likely to sustain thermal convection for the age of the solar system, but cool to a subadiabatic, conductive state that cannot maintain a dynamo because of the gravitational energy release and the chemically driven convection that accompany inner core growth. The models presented include realistic pressure- and composition-dependent freezing curves for the core, and material parameters are chosen so that correct present-day values of heat outflow, upper mantle temperature and viscosity, and inner core radius, are obtained for the earth. 116 references

  16. Four component magnetized dusty plasma containing non-thermal electrons

    International Nuclear Information System (INIS)

    Multicomponent plasmas are of great attraction for research in dusty plasmas. In the present research paper, dusty plasma consisting of non-thermal electrons, Maxwellian ions, negatively and positively charged warm adiabatic dust particles, is considered. The Korteweg-de Vries (KdV) equation which describes the basic features of the electrostatic solitary structures is derived by use of reductive perturbation method and solved for solitary wave solution. The effect of externally applied magnetic field and non-thermal electrons is found to modify the properties of the dust acoustic solitary potential significantly. The implications of these results for some space and astrophysical dusty plasma systems especially in planetary ring and cometary tails, are briefly mentioned.

  17. Magnetism and thermal evolution of the terrestrial planets

    Science.gov (United States)

    Stevenson, D. J.; Spohn, T.; Schubert, G.

    1983-01-01

    The absence in the cases of Venus and Mars of the substantial intrinsic magnetic fields of the earth and Mercury is considered, in light of thermal history calculations which suggest that, while the cores of Mercury and the earth are continuing to freeze, the cores of Venus and Mars may still be completely liquid. It is noted that completely fluid cores, lacking intrinsic heat sources, are not likely to sustain thermal convection for the age of the solar system, but cool to a subadiabatic, conductive state that cannot maintain a dynamo because of the gravitational energy release and the chemically driven convection that accompany inner core growth. The models presented include realistic pressure- and composition-dependent freezing curves for the core, and material parameters are chosen so that correct present-day values of heat outflow, upper mantle temperature and viscosity, and inner core radius, are obtained for the earth.

  18. Thermal effects on transverse domain wall dynamics in magnetic nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Leliaert, J., E-mail: jonathan.leliaert@ugent.be [Department of Electrical Energy, Systems and Automation, Ghent University, 9000 Gent (Belgium); Department of Solid State Sciences, Ghent University, 9000 Gent (Belgium); Van de Wiele, B.; Vandermeulen, J.; Coene, A.; Dupré, L. [Department of Electrical Energy, Systems and Automation, Ghent University, 9000 Gent (Belgium); Vansteenkiste, A.; Waeyenberge, B. Van [Department of Solid State Sciences, Ghent University, 9000 Gent (Belgium); Laurson, L. [COMP Centre of Excellence and Helsinki Institute of Physics, Department of Applied Physics, Aalto University School of Science, P.O. Box 11100, FI-00076 Aalto (Finland); Durin, G. [Istituto Nazionale di Ricerca Metrologica, Strada delle Cacce 91, 10135 Torino (Italy); ISI Foundation, Via Alassio 11/c, 10126 Torino (Italy)

    2015-05-18

    Magnetic domain walls are proposed as data carriers in future spintronic devices, whose reliability depends on a complete understanding of the domain wall motion. Applications based on an accurate positioning of domain walls are inevitably influenced by thermal fluctuations. In this letter, we present a micromagnetic study of the thermal effects on this motion. As spin-polarized currents are the most used driving mechanism for domain walls, we have included this in our analysis. Our results show that at finite temperatures, the domain wall velocity has a drift and diffusion component, which are in excellent agreement with the theoretical values obtained from a generalized 1D model. The drift and diffusion component are independent of each other in perfect nanowires, and the mean square displacement scales linearly with time and temperature.

  19. Ferroelectric, Thermal, and Magnetic Characteristics of Praseodymium Malonate Hexahydrate Crystals

    Science.gov (United States)

    Ahmad, Nazir; Ahmad, M. M.; Kotru, P. N.

    2016-04-01

    Gel-grown single crystals of [Pr2(C3H2O4)3(H2O)6] exhibit remarkably flat habit faces, the most predominant being {110}. High-resolution x-ray diffraction analysis showed that the crystals are free from structural grain boundaries, which is the key requirement for single crystals for use in the microelectronics industry to serve as low-dielectric-constant ferroelectric material. The dielectric behavior recorded on {110} planes of single crystals shows that the crystal is ferroelectric with transition temperature T c = 135°C, which differs from the Curie-Weiss temperature T 0 by 2°C (T 0 TGA), differential thermal analysis (DTA), and differential scanning calorimetry (DSC). The magnetic susceptibility and magnetic moment are calculated to be 30.045 × 10-6 emu and 3.092 BM, respectively.

  20. Using airborne thermal infrared imagery and helicopter EM conductivity to locate mine pools and discharges in the Kettle Creek watershed, north-central Pennsylvania

    Energy Technology Data Exchange (ETDEWEB)

    Love, E. (Shaw Environmental, Monroeville, PA); Hammack, R.W.; Harbert, W.P. (Univ. of Pittsburgh); Sams, J.I.; Veloski, G.A.; Ackman, T.E.

    2005-11-01

    The Kettle Creek watershed contains 50–100-year-old surface and underground coal mines that are a continuing source of acid mine drainage (AMD). To characterize the mining-altered hydrology of this watershed, an airborne reconnaissance was conducted in 2002 using airborne thermal infrared imagery (TIR) and helicopter-mounted electromagnetic (HEM) surveys. TIR uses the temperature differential between surface water and groundwater to locate areas where groundwater emerges at the surface. TIR anomalies located in the survey included seeps and springs, as well as mine discharges. In a follow-up ground investigation, hand-held GPS units were used to locate 103 of the TIR anomalies. Of the sites investigated, 26 correlated with known mine discharges, whereas 27 were previously unknown. Seven known mine discharges previously obscured from TIR imagery were documented. HEM surveys were used to delineate the groundwater table and also to locate mine pools, mine discharges, and groundwater recharge zones. These surveys located 12 source regions and flow paths for acidic, metal-containing (conductive) mine drainage; areas containing acid-generating mine spoil; and areas of groundwater recharge and discharge, as well as identifying potential mine discharges previously obscured from TIR imagery by nondeciduous vegetation. Follow-up ground-based electromagnetic surveys verified the results of the HEM survey. Our study suggests that airborne reconnaissance can make the remediation of large watersheds more efficient by focusing expensive ground surveys on small target areas.

  1. Magnetic fields and thermal flux inhibition in inertial confinement fusion

    International Nuclear Information System (INIS)

    Of critical concern in directly driven laser fusion systems is the understanding of electron thermal transport between the region where laser light is absorbed and the ablation layer where the high pressures which accelerate the imploding shell are generated. Evidence has accumulated over the past several years which indicates that the heat flow may be strongly inhibited. Computer hydrodynamics models used to interpret experimental results have typically employed, in an ad hoc fashion, strong flux-limited diffusion which has led to fairly widespread acceptance of a flux inhibition value near f=0.03. It is shown in this paper that the observed flux inhibition can stem directly from the strong magnetic fields generated at the ablation layer as a result of modest laser asymmetries. These fields are shed from the ablation layer and fill the overdense region which strongly influences the thermal transport. The self-consistent numerical simulation of thermal transport in this environment shows strong thermal flux inhibition as interpreted from the following computational measurements: (1) reduced ablation pressures, (2) reduced implosion velocities, (3) reduced mass ablation rates, (4) density profile flattening, and (5) reduced classical absorption; all of which have been experimentally observed. The mass ablation rates obtained from the self-consistent two-dimensional model agree well with a one-dimensional model using an imposed flux inhibition factor of 0.03. (author)

  2. Thermal convection in a nonlinear non-Newtonian magnetic fluid

    Science.gov (United States)

    Laroze, D.; Pleiner, H.

    2015-09-01

    We report theoretical and numerical results on thermal convection of a magnetic fluid in a viscoelastic carrier liquid. The viscoelastic properties are described by a general nonlinear viscoelastic model that contains as special cases the standard phenomenological constitutive equations for the stress tensor. In order to explore numerically the system we perform a truncated Galerkin expansion obtaining a generalized Lorenz system with ten modes. We find numerically that the system has stationary, periodic and chaotic regimes. We establish phase diagrams to identify the different dynamical regimes as a function of the Rayleigh number and the viscoelastic material parameters.

  3. Thermal capability of JT-60 magnetic limiter plate

    International Nuclear Information System (INIS)

    Thermal analysis of the JT-60 magnetic limiter (ML) plate has been made to investigate the thermal capability for its use in the ML operation. The following heat load models are considered to simulate the possible thermal conditions in the operation. Gaussian heat flux distribution with a half width of 3 cm is considered as charged particle heat load. In order to simulate the swing of the separatrix magnetic surface on the ML plate, both time averaged and sinusoidally moving heat flux are used. The effect of remote cooling by radiation (photon and charge exchanged neutral particle) in the ML region is modeled by the spacially distributed radiative heat sources. The ML plate is modeled by 2-dimensional slab geometry allowing interface conductance between the ML plate and the cooling duct. The effect of radiative heat transfer to the cooling duct and convective heat transfer to the cooling gas are included. Results show that in general the operation with the maximum heating pulse length of 10 s is not allowable in the absence of remote cooling. In a typical case when radiation loss in the ML region amounts to 70 % of the total power flow to the ML chamber, the power flow to the ML plate reduces by half and the peak heat flux also reduces by half or more. In addition, this heat flux is further decreased by half with +- 3.5 cm swing. This analysis presents the relationship between various heat loads and the ML plate temperature and hence the thermally allowable operational range on the ML plate. (author)

  4. Aerial gamma ray and magnetic survey: Mississippi and Florida airborne survey, Russellville quadrangle, Arkansas

    International Nuclear Information System (INIS)

    The Russellville quadrangle in north central Arkansas overlies thick Paleozoic sediments of the Arkoma Basin. These Paleozoics dominate surface exposure except where covered by Quaternary alluvial materials. Examination of available literature shows no known uranium deposits (or occurrences) within the quadrangle. Eighty-eight groups of uranium samples were defined as anomalies and are discussed briefly. None were considered significant, and most appeared to be of cultural origin. Magnetic data show character that suggest structural and/or lithologic complexity, but imply relatively deep-seated sources

  5. Mapping Weathering and Alteration Minerals in the Comstock and Geiger Grade Areas using Visible to Thermal Infrared Airborne Remote Sensing Data

    Science.gov (United States)

    Vaughan, Greg R.; Calvin, Wendy M.

    2005-01-01

    To support research into both precious metal exploration and environmental site characterization a combination of high spatial/spectral resolution airborne visible, near infrared, short wave infrared (VNIR/SWIR) and thermal infrared (TIR) image data were acquired to remotely map hydrothermal alteration minerals around the Geiger Grade and Comstock alteration regions, and map the mineral by-products of weathered mine dumps in Virginia City. Remote sensing data from the Airborne Visible Infrared Imaging Spectrometer (AVIRIS), SpecTIR Corporation's airborne hyperspectral imager (HyperSpecTIR), the MODIS-ASTER airborne simulator (MASTER), and the Spatially Enhanced Broadband Array Spectrograph System (SEBASS) were acquired and processed into mineral maps based on the unique spectral signatures of image pixels. VNIR/SWIR and TIR field spectrometer data were collected for both calibration and validation of the remote data sets, and field sampling, laboratory spectral analyses and XRD analyses were made to corroborate the surface mineralogy identified by spectroscopy. The resulting mineral maps show the spatial distribution of several important alteration minerals around each study area including alunite, quartz, pyrophyllite, kaolinite, montmorillonite/muscovite, and chlorite. In the Comstock region the mineral maps show acid-sulfate alteration, widespread propylitic alteration and extensive faulting that offsets the acid-sulfate areas, in contrast to the larger, dominantly acid-sulfate alteration exposed along Geiger Grade. Also, different mineral zones within the intense acid-sulfate areas were mapped. In the Virginia City historic mining district the important weathering minerals mapped include hematite, goethite, jarosite and hydrous sulfate minerals (hexahydrite, alunogen and gypsum) located on mine dumps. Sulfate minerals indicate acidic water forming in the mine dump environment. While there is not an immediate threat to the community, there are clearly sources of

  6. Atom Interferometry in Space: Thermal Management and Magnetic Shielding

    CERN Document Server

    Milke, Alexander; Gürlebeck, Norman; Rievers, Benny; Herrmann, Sven; Schuldt, Thilo; Braxmaier, Claus

    2014-01-01

    Atom interferometry is an exciting tool to probe fundamental physics. It is considered especially apt to test the universality of free fall using two different sorts of atoms. The increasing sensitivity required for this kind of experiment sets severe requirements on its environments, instrument control, and systematic effects. This can partially be mitigated by going to space as was proposed, for example, in the STE-QUEST mission. However, the requirements on the instrument are still very challenging. For example, the specifications of STE-QUEST mission imply that the Feshbach coils of the atom interferometer are allowed to change their radius only by about 70 nm or 7x10E-5 % due to thermal expansion although they consume an average power of 22 W. Also Earth's magnetic field has to be suppressed by a factor $10^5$. We show in this article that with the right design such thermal and magnetic requirements can indeed be met and that these are not an impediment for the exciting physics possible with atom interfe...

  7. Atom interferometry in space: Thermal management and magnetic shielding

    International Nuclear Information System (INIS)

    Atom interferometry is an exciting tool to probe fundamental physics. It is considered especially apt to test the universality of free fall by using two different sorts of atoms. The increasing sensitivity required for this kind of experiment sets severe requirements on its environments, instrument control, and systematic effects. This can partially be mitigated by going to space as was proposed, for example, in the Spacetime Explorer and Quantum Equivalence Principle Space Test (STE-QUEST) mission. However, the requirements on the instrument are still very challenging. For example, the specifications of the STE-QUEST mission imply that the Feshbach coils of the atom interferometer are allowed to change their radius only by about 260 nm or 2.6 × 10−4 % due to thermal expansion although they consume an average power of 22 W. Also Earth's magnetic field has to be suppressed by a factor of 105. We show in this article that with the right design such thermal and magnetic requirements can indeed be met and that these are not an impediment for the exciting physics possible with atom interferometers in space

  8. Effect of magnetic field on thermal conductivity and viscosity of a magnetic nanofluid loaded with carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Shahsavar, Amin [Kermanshah University of Technology, Kermanshah (Iran, Islamic Republic of); Salimpour, Mohammad Reza; Saghafian, Mohsen [Isfahan University of Technology, Isfahan (Iran, Islamic Republic of); Shafii, M. B. [Sharif University of Technology, Tehran(Iran, Islamic Republic of)

    2016-02-15

    The present work examines experimentally the effect of magnetic field on the viscosity and thermal conductivity of a hybrid nanofluid containing tetramethylammonium hydroxide (TMAH) coated Fe{sub 3}O{sub 4} nanoparticles and Gum arabic (GA) coated carbon nanotubes (CNTs). The hybrid nanofluid was prepared by using ultrasonic dispersion method. Magnetic field was created by a pair of spaced apart magnet plates. The effect of temperature on the time variation of thermal conductivity under applied magnetic field was also investigated. According to the results of this study, viscosity of the hybrid nanofluid increases with the strength of magnetic field, while it decreases with the increase of temperature. Additionally, it is found that the hybrid nanofluid behaves as a shear thinning fluid at low shear rates while it exhibits Newtonian behavior at high shear rates. Furthermore, results show that when an external magnetic field is applied to the studied magnetic nanofluids, the thermal conductivity experiences a peak.

  9. An Assessment of Polynomial Regression Techniques for the Relative Radiometric Normalization (RRN of High-Resolution Multi-Temporal Airborne Thermal Infrared (TIR Imagery

    Directory of Open Access Journals (Sweden)

    Mir Mustafizur Rahman

    2014-11-01

    Full Text Available Thermal Infrared (TIR remote sensing images of urban environments are increasingly available from airborne and satellite platforms. However, limited access to high-spatial resolution (H-res: ~1 m TIR satellite images requires the use of TIR airborne sensors for mapping large complex urban surfaces, especially at micro-scales. A critical limitation of such H-res mapping is the need to acquire a large scene composed of multiple flight lines and mosaic them together. This results in the same scene components (e.g., roads, buildings, green space and water exhibiting different temperatures in different flight lines. To mitigate these effects, linear relative radiometric normalization (RRN techniques are often applied. However, the Earth’s surface is composed of features whose thermal behaviour is characterized by complexity and non-linearity. Therefore, we hypothesize that non-linear RRN techniques should demonstrate increased radiometric agreement over similar linear techniques. To test this hypothesis, this paper evaluates four (linear and non-linear RRN techniques, including: (i histogram matching (HM; (ii pseudo-invariant feature-based polynomial regression (PIF_Poly; (iii no-change stratified random sample-based linear regression (NCSRS_Lin; and (iv no-change stratified random sample-based polynomial regression (NCSRS_Poly; two of which (ii and iv are newly proposed non-linear techniques. When applied over two adjacent flight lines (~70 km2 of TABI-1800 airborne data, visual and statistical results show that both new non-linear techniques improved radiometric agreement over the previously evaluated linear techniques, with the new fully-automated method, NCSRS-based polynomial regression, providing the highest improvement in radiometric agreement between the master and the slave images, at ~56%. This is ~5% higher than the best previously evaluated linear technique (NCSRS-based linear regression.

  10. Fast magnetic peak switching for thermal ionization mass spectrometers

    International Nuclear Information System (INIS)

    Common practice in thermal ionization mass spectrometry is to make repeated and rapid comparisons between isotopes of interest by switching the magnetic deflection field sequentially between the values required to deflect each isotope through the collector slit. After each step in the field value (peak switch) it is necessary to pause before logging data, in order to allow the system response to settle to the point where it does not affect the precision of the isotopic ratio determination. The dynamics of the field stabilization system are the principle contributors to this delay period. The system characteristics applicable to a field-controlled magnet system are analyzed in this paer. Possible areas where the step response may be improved by the application of modern control theory are outlined. It is shown that any field-stabilized magnet system can be optimized for step response by the synthesis of a discrete control system. Discrete digital control, i.e. a software implementation, allows system optimization without the necessity for hardware modification, which would be difficult, expensive and possibility in some cases impractical. (orig.)

  11. Magnetic nanoparticles for thermal lysis and application in cancer treatment

    Science.gov (United States)

    Das, Sumana; Javvaji, Brahmanandam; Veerla, Sarath Chandra; Roy Mahapatra, D.

    2016-03-01

    Chemotherapy and radiation-therapy are conventional treatment procedure of cancer. Though radiation therapy is very common practice for cancer treatment, it has limitations including incomplete and non specific destruction. Heating characteristics of magnetic nanoparticle (MNP) is modelled using molecular dynamics simulation setup. This model would give an understanding for the treatment of cancer cell through MNP associated radiation-therapy. In this paper, alternating magnetic field driven heat generation of MNP is studied using classical molecular dynamics. Temperature is measured as an ensemble average of velocity of the atoms. Temperature stabilization is achieved. Under this simulation setting with certain parameters, 45°C temperature was obtained in our simulations. Simulation data would be helpful for experimental analysis to treat cancerous cell in presence of MNP under exposure to radiofrequency. The in vitro thermal characteristics of magnetite nanoparticles using magnetic coil of various frequencies (5, 7.5, 10 and 15 kHz), the saturation temperature was found at 0.5 mg/mL concentration. At frequency 50 kHz the live/dead and MTT assay was performed on magnetite nanoparticles using MC3T3 cells for 10 min duration. Low radio frequency (RF) radiation induced localized heat into the metallic nanoparticles which is clearly understood using the molecular dynamics simulation setup. Heating of nanoparticle trigger the killing of the tumor cells, acts as a local therapy, as it generates less side effects in comparison to other treatments like chemotherapy and radiation therapy.

  12. Thermal remote sensing from Airborne Hyperspectral Scanner data in the framework of the SPARC and SEN2FLEX projects: an overview

    Directory of Open Access Journals (Sweden)

    J. A. Sobrino

    2009-06-01

    Full Text Available The AHS (Airborne Hyperspectral Scanner instrument has 80 spectral bands covering the visible and near infrared (VNIR, short wave infrared (SWIR, mid infrared (MIR and thermal infrared (TIR spectral range. The instrument is operated by Instituto Nacional de Técnica Aerospacial (INTA, and it has been involved in several field campaigns since 2004.

    This paper presents an overview of the work performed with the AHS thermal imagery provided in the framework of the SPARC and SEN2FLEX campaigns, carried out respectively in 2004 and 2005 over an agricultural area in Spain. The data collected in both campaigns allowed for the first time the development and testing of algorithms for land surface temperature and emissivity retrieval as well as the estimation of evapotranspiration from AHS data. Errors were found to be around 1.5 K for land surface temperature and 1 mm/day for evapotranspiration.

  13. Thermal remote sensing from Airborne Hyperspectral Scanner data in the framework of the SPARC and SEN2FLEX projects: an overview

    Directory of Open Access Journals (Sweden)

    Q. Shen

    2009-11-01

    Full Text Available The AHS (Airborne Hyperspectral Scanner instrument has 80 spectral bands covering the visible and near infrared (VNIR, short wave infrared (SWIR, mid infrared (MIR and thermal infrared (TIR spectral range. The instrument is operated by Instituto Nacional de Técnica Aerospacial (INTA, and it has been involved in several field campaigns since 2004.

    This paper presents an overview of the work performed with the AHS thermal imagery provided in the framework of the SPARC and SEN2FLEX campaigns, carried out respectively in 2004 and 2005 over an agricultural area in Spain. The data collected in both campaigns allowed for the first time the development and testing of algorithms for land surface temperature and emissivity retrieval as well as the estimation of evapotranspiration from AHS data. Errors were found to be around 1.5 K for land surface temperature and 1 mm/day for evapotranspiration.

  14. Geological interpretation of Eastern Cuba Laterites from an airborne magnetic and radioactive isotope survey

    Energy Technology Data Exchange (ETDEWEB)

    Batista, J.A; Blanco, J [Departamento de Geologia, Instituto Superior Minero Metalurgico de Moa, (Cuba); Perez-Flores, M.A [Centro de Investigacion Cientifica y Educacion Superior de Ensenada, Baja California (Mexico)

    2008-04-15

    In eastern Cuba area several geophysical techniques have been applied to distinguish the main geological characteristics of the laterites which are of economical importance for the extraction of iron, nickel and chrome. The geophysical measurements include an aeromagnetic survey and thorium (eTh), potassium (K) and uranium (eU) isotope measurements. The results of gamma spectrometer measurements make a distinction between laterite reservoirs. The application of the magnetic and isotope methods allowed the determination of the distribution and development of the laterite crust, as well as the determination of hydrothermal alterations affecting the laterites, which is very useful for mining exploration and exploitation. Such alterations indicate the presence of silicates, which have negative effects on the metallurgic process. It is known that laterite crust has a high content of eU and eTh. [Spanish] Se han utilizado varias tecnicas geofisicas en la region oriental de Cuba para distinguir las principales caracteristicas geologicas de las lateritas, que poseen importancia economica para la extraccion de hierro, niquel y cobalto. Las mediciones geofisicas incluyen un estudio aeromagnetico y mediciones de isotopos de torio (eTh), potasio (K) y uranio (eU). Los resultados de las mediciones espectrometricas establecen diferencias entre los yacimientos de lateritas. De la aplicacion del metodo magnetico e isotopico se determino la distribucion y desarrollo de las cortezas lateriticas, asi como la ubicacion de alteraciones hidrotermales que afectan a las lateritas, lo cual es muy util durante la exploracion y explotacion minera. Esas alteraciones indican la presencia de silicatos, que tienen un efecto negativo en el proceso metalurgico. Se conoce que las cortezas lateriticas tienen altos contenidos de eU y eTh. De los contenidos de eU y eTh se infiere que las lateritas de la region de Moa se formaron antes que las de Mayari. De estas mediciones fue posible inferir el

  15. Thermally induced magnetization switching in Gd/Fe multilayers

    Science.gov (United States)

    Xu, C.; Ostler, T. A.; Chantrell, R. W.

    2016-02-01

    A theoretical model of Gd/Fe multilayers is constructed using the atomistic spin dynamics formalism. By varying the thicknesses and number of layers we have shown that a strong dependence of the energy required for thermally induced magnetization switching (TIMS) is present; with a larger number of interfaces, lower energy is required. The results of the layer resolved dynamics show that the reversal process of the multilayered structures, similar to that of a GdFeCo alloy, is driven by the antiferromagnetic interaction between the transition-metal and rare-earth components. Finally, while the presence of the interface drives the reversal process, we show here that the switching process does not initiate at the surface but from the layers furthest from it, a departure from the alloy behavior which expands the classes of material types exhibiting TIMS.

  16. Magnetic susceptibilities and thermal expansion of artificial graphites

    International Nuclear Information System (INIS)

    Starting from measurements of the magnetic susceptibility made in the two principal directions of a graphite bar, the distribution function of the normals to the carbon planes in the crystallites has been evaluated. The effect of different variation in the manufacturing process on this crystalline anisotropy has been studied. From this crystalline anisotropy we have calculated the thermal expansion coefficient possessed by a compact mass of crystallites having exactly the same orientational anisotropy as the porous body consideration. The difference between this and the observed expansion coefficient leads to the determination of the expansion of the non-graphitic part of the mass which turns out to have a negative value and is also anisotropic. We have attempted to draw some conclusions from this result. (author)

  17. Thermal dependence of magnetic springs location in a DyFe2/YFe2 superlattice

    Science.gov (United States)

    Dumesnil, K.; Dufour, C.; Mangin, Ph.; Wilhelm, F.; Rogalev, A.

    2004-06-01

    Element selective x-ray magnetic circular dichroism measurements have been performed to unravel the complex magnetization reversal process occurring in antiferromagnetically exchange-coupled Laves phase superlattices. The separate investigation of each magnetic compound in a [DyFe2 (50 Å)/YFe2 (200 Å)] superlattice has enlightened a drastic thermal variation towards an unexpected high-temperature regime, where the magnetization in the hard layers first reverses in positive field, whereas the magnetization in the soft ones remains stuck along the field direction. This transfer of the interface magnetic twists towards the hard layers permits us to explain the thermal evolution of the coercive field.

  18. Thermal and magnetic properties of chitosan-iron oxide nanoparticles.

    Science.gov (United States)

    Soares, Paula I P; Machado, Diana; Laia, César; Pereira, Laura C J; Coutinho, Joana T; Ferreira, Isabel M M; Novo, Carlos M M; Borges, João Paulo

    2016-09-20

    Chitosan is a biopolymer widely used for biomedical applications such as drug delivery systems, wound healing, and tissue engineering. Chitosan can be used as coating for other types of materials such as iron oxide nanoparticles, improving its biocompatibility while extending its range of applications. In this work iron oxide nanoparticles (Fe3O4 NPs) produced by chemical precipitation and thermal decomposition and coated with chitosan with different molecular weights were studied. Basic characterization on bare and chitosan-Fe3O4 NPs was performed demonstrating that chitosan does not affect the crystallinity, chemical composition, and superparamagnetic properties of the Fe3O4 NPs, and also the incorporation of Fe3O4 NPs into chitosan nanoparticles increases the later hydrodynamic diameter without compromising its physical and chemical properties. The nano-composite was tested for magnetic hyperthermia by applying an alternating current magnetic field to the samples demonstrating that the heating ability of the Fe3O4 NPs was not significantly affected by chitosan. PMID:27261762

  19. Chiral Charge Erasure via Thermal Fluctuations of Magnetic Helicity

    CERN Document Server

    Long, Andrew J

    2016-01-01

    We consider a relativistic plasma of fermions coupled to an Abelian gauge field and carrying a chiral charge asymmetry, which might arise in the early Universe through baryogenesis. It is known that on large length scales, $\\lambda \\gtrsim 1/(\\alpha \\mu_5)$, the chiral anomaly opens an instability toward the erasure of chiral charge and growth of magnetic helicity. Here the chemical potential $\\mu_{5}$ parametrizes the chiral asymmetry and $\\alpha$ is the fine-structure constant. We study the process of chiral charge erasure through the thermal fluctuations of magnetic helicity and contrast with the well-studied phenomenon of Chern-Simons number diffusion. Through the fluctuation-dissipation theorem we estimate the amplitude and time scale of helicity fluctuations on the length scale $\\lambda$, finding $\\delta \\mathcal{H} \\sim \\lambda T$ and $\\tau \\sim \\alpha \\lambda^3 T^2$ for a relativistic plasma at temperature $T$. We argue that the presence of a chiral asymmetry allows the helicity to grow diffusively fo...

  20. Scanning Nanospin Ensemble Microscope for Nanoscale Magnetic and Thermal Imaging.

    Science.gov (United States)

    Tetienne, Jean-Philippe; Lombard, Alain; Simpson, David A; Ritchie, Cameron; Lu, Jianing; Mulvaney, Paul; Hollenberg, Lloyd C L

    2016-01-13

    Quantum sensors based on solid-state spins provide tremendous opportunities in a wide range of fields from basic physics and chemistry to biomedical imaging. However, integrating them into a scanning probe microscope to enable practical, nanoscale quantum imaging is a highly challenging task. Recently, the use of single spins in diamond in conjunction with atomic force microscopy techniques has allowed significant progress toward this goal, but generalization of this approach has so far been impeded by long acquisition times or by the absence of simultaneous topographic information. Here, we report on a scanning quantum probe microscope which solves both issues by employing a nanospin ensemble hosted in a nanodiamond. This approach provides up to an order of magnitude gain in acquisition time while preserving sub-100 nm spatial resolution both for the quantum sensor and topographic images. We demonstrate two applications of this microscope. We first image nanoscale clusters of maghemite particles through both spin resonance spectroscopy and spin relaxometry, under ambient conditions. Our images reveal fast magnetic field fluctuations in addition to a static component, indicating the presence of both superparamagnetic and ferromagnetic particles. We next demonstrate a new imaging modality where the nanospin ensemble is used as a thermometer. We use this technique to map the photoinduced heating generated by laser irradiation of a single gold nanoparticle in a fluid environment. This work paves the way toward new applications of quantum probe microscopy such as thermal/magnetic imaging of operating microelectronic devices and magnetic detection of ion channels in cell membranes. PMID:26709529

  1. Thermal entanglement in a mixed-spin Heisenberg XXZ model under a nonuniform external magnetic field

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The thermal entanglement in (1/2,1) mixed-spin Heisenberg XXZ model is investigated under an external nonuniform magnetic field. In the uniform magnetic field system,the critical magnetic field Bc and critical temperature Tc are increased by increasing the anisotropic parameter k. The degree of magnetic field b plays an important role in improving the critical temperature and enlarging the region of entan-glement in the nonuniform magnetic field system.

  2. Structural Design and Thermal Analysis for Thermal Shields of the MICE Coupling Magnets

    International Nuclear Information System (INIS)

    A superconducting coupling magnet made from copper matrix NbTi conductors operating at 4 K will be used in the Muon Ionization Cooling Experiment (MICE) to produce up to 2.6 T on the magnet centerline to keep the muon beam within the thin RF cavity indows. The coupling magnet is to be cooled by two cryocoolers with a total cooling capacity of 3 W at 4.2 K. In order to keep a certain operating temperature margin, the most important is to reduce the heat leakage imposed on cold surfaces of coil cold mass assembly. An ntermediate temperature shield system placed between the coupling coil and warm vacuum chamber is adopted. The shield system consists of upper neck shield, main shields, flexible connections and eight supports, which is to be cooled by the first stage cold heads of two ryocoolers with cooling capacity of 55 W at 60 K each. The maximum temperature difference on the shields should be less than 20 K, so the thermal analyses for the shields with different thicknesses, materials, flexible connections for shields' cooling and structure design for heir supports were carried out. 1100 Al is finally adopted and the maximum temperature difference is around 15 K with 4 mm shield thickness. The paper is to present detailed analyses on the shield system design.

  3. Magnetic and thermal properties of high Tc superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Wonchoon.

    1990-09-21

    Measurements of the normal state magnetic susceptibility {chi}(T) of YBa{sub 2}Cu{sub 3}O{sub 7}, Bi{sub 1.8}Pb{sub 0.2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}}, and Bi{sub 2{minus}x}Pb{sub x}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10+{delta}} (x = 0.2 and 0.25) were carried out. All {chi}(T) data show negative curvature below {approximately}2{Tc}. The data for YBa{sub 2}Cu{sub 3}O{sub 7} are in excellent agreement with a new calculation of the superconducting fluctuation diamagnetism. From the analysis, we infer s-wave pairing and microscopic parameters are obtained. For {chi}(T) of YBa{sub 2}Cu{sub 3}O{sub 7}, part of the negative curvature is inferred to arise from the normal state background. We find a strong temperature dependent anisotropy {delta}{chi} {equivalent to} {chi}{sub c} {minus} {chi}{sub ab} and estimate the normal state spin contributions to {chi}(T). The heat capacity C(T) of YBa{sub 2}Cu{sub 3}O{sub 7} is reported for 0.4 K < T < 400 K in zero and 70 kG magnetic fields. In addition to the feature associated with the onset of the superconductivity at {Tc}, two anomalies in C(T) were observed near 74 K and 330 K, with another possible anomaly near 102 K; the temperatures at which they occur correlate with anomalies in {chi}(T) and ultransonic measurements. The occurrence of the anomaly at {approx equal} 330 K is found to be sample-dependent. The influences of a magnetic field and the thermal and/or magnetic field treatment history dependence of a pellet sample on C(T), the entropy and the influence of superconducting fluctuations on C(T) near {Tc}, and the possible source of the observed intrinsic nonzero {gamma}(0) at low T are discussed.

  4. Thermal modelling of a high speed permanent magnet synchronous machine / Andries J. Grobler

    OpenAIRE

    Grobler, Andries Johannes

    2011-01-01

    Thermal modelling is of great importance in all electric machines but especially in permanent magnet synchronous machines (PMSMs). The thermally fragile permanent magnets (PMs) can more easily be demagnetized at high temperatures. When high speed machines are considered, heat extraction surfaces are small due to the higher energy density. This thesis focuses on the thermal modelling of a high speed slotless PMSM using analytical techniques. From literature it is clear that anal...

  5. Thermal activation-induced sweep-rate dependence of magnetic switching astroid

    International Nuclear Information System (INIS)

    We examine the sweep-rate dependence of magnetic switching field, Hs, in submicron magnetic tunnel junctions where shape anisotropy is dominant. Experimental data support the use of a single-domain thermal activation model for description of activated magnetic reversal in junctions 0.2 by 0.5 μm or less in size. A scaling law is obtained for the thermal activation energy which varies as the cube of junction size. [copyright] 2001 American Institute of Physics

  6. Thermally induced magnetization switching in Fe/MnAs/GaAs(001): selectable magnetic configurations by temperature and field control.

    Science.gov (United States)

    Spezzani, Carlo; Vidal, Franck; Delaunay, Renaud; Eddrief, Mahmoud; Marangolo, Massimiliano; Etgens, Victor H; Popescu, Horia; Sacchi, Maurizio

    2015-01-01

    Spintronic devices currently rely on magnetization control by external magnetic fields or spin-polarized currents. Developing temperature-driven magnetization control has potential for achieving enhanced device functionalities. Recently, there has been much interest in thermally induced magnetisation switching (TIMS), where the temperature control of intrinsic material properties drives a deterministic switching without applying external fields. TIMS, mainly investigated in rare-earth-transition-metal ferrimagnets, has also been observed in epitaxial Fe/MnAs/GaAs(001), where it stems from a completely different physical mechanism. In Fe/MnAs temperature actually modifies the surface dipolar fields associated with the MnAs magnetic microstructure. This in turn determines the effective magnetic field acting on the Fe overlayer. In this way one can reverse the Fe magnetization direction by performing thermal cycles at ambient temperatures. Here we use element selective magnetization measurements to demonstrate that various magnetic configurations of the Fe/MnAs/GaAs(001) system are stabilized predictably by acting on the thermal cycle parameters and on the presence of a bias field. We show in particular that the maximum temperature reached during the cycle affects the final magnetic configuration. Our findings show that applications are possible for fast magnetization switching, where local temperature changes are induced by laser excitations. PMID:25631753

  7. Thermally induced magnetization switching in Fe/MnAs/GaAs(001): selectable magnetic configurations by temperature and field control

    Science.gov (United States)

    Spezzani, Carlo; Vidal, Franck; Delaunay, Renaud; Eddrief, Mahmoud; Marangolo, Massimiliano; Etgens, Victor H.; Popescu, Horia; Sacchi, Maurizio

    2015-01-01

    Spintronic devices currently rely on magnetization control by external magnetic fields or spin-polarized currents. Developing temperature-driven magnetization control has potential for achieving enhanced device functionalities. Recently, there has been much interest in thermally induced magnetisation switching (TIMS), where the temperature control of intrinsic material properties drives a deterministic switching without applying external fields. TIMS, mainly investigated in rare-earth–transition-metal ferrimagnets, has also been observed in epitaxial Fe/MnAs/GaAs(001), where it stems from a completely different physical mechanism. In Fe/MnAs temperature actually modifies the surface dipolar fields associated with the MnAs magnetic microstructure. This in turn determines the effective magnetic field acting on the Fe overlayer. In this way one can reverse the Fe magnetization direction by performing thermal cycles at ambient temperatures. Here we use element selective magnetization measurements to demonstrate that various magnetic configurations of the Fe/MnAs/GaAs(001) system are stabilized predictably by acting on the thermal cycle parameters and on the presence of a bias field. We show in particular that the maximum temperature reached during the cycle affects the final magnetic configuration. Our findings show that applications are possible for fast magnetization switching, where local temperature changes are induced by laser excitations. PMID:25631753

  8. Effects of terbium sulfide addition on magnetic properties, microstructure and thermal stability of sintered Nd–Fe–B magnets

    Science.gov (United States)

    Xiang-Bin, Li; Shuo, Liu; Xue-Jing, Cao; Bei-Bei, Zhou; Ling, Chen; A-Ru, Yan; Gao-Lin, Yan

    2016-07-01

    To increase coercivity and thermal stability of sintered Nd–Fe–B magnets for high-temperature applications, a novel terbium sulfide powder is added into (Pr0.25Nd0.75)30.6Cu0.15FebalB1 (wt.%) basic magnets. The effects of the addition of terbium sulfide on magnetic properties, microstructure, and thermal stability of sintered Nd–Fe–B magnets are investigated. The experimental results show that by adding 3 wt.% Tb2S3, the coercivity of the magnet is remarkably increased by about 54% without a considerable reduction in remanence and maximum energy product. By means of the electron probe microanalyzer (EPMA) technology, it is observed that Tb is mainly present in the outer region of 2:14:1 matrix grains and forms a well-developed Tb-shell phase, resulting in enhancement of H A, which accounts for the coercivity enhancement. Moreover, compared with Tb2S3-free magnets, the reversible temperature coefficients of remanence (α) and coercivity (β) and the irreversible flux loss of magnetic flow (h irr) values of Tb2S3-added magnets are improved, indicating that the thermal stability of the magnets is also effectively improved. Project supported by the Science Funds from the Ministry of Science and Technology, China (Grant Nos. 2014DFB50130 and 2011CB612304) and the National Natural Science Foundation of China (Grant Nos. 51172168 and 51072139).

  9. Measure Analysis on Magnetic Effect of Airborne Products%航空机载产品磁影响测量分析

    Institute of Scientific and Technical Information of China (English)

    毛洪涛

    2016-01-01

    This paper introduces the technical requirements and the measuring method of magnetic influence measuring standard for the airborne products. And it deeply analyzes the principle of magnetic effect measurement, clarifies the confusing certainty principles for magnetic effect'limit value in the standard, and detailedly explains the method for magnetometer to measure magnetic effect. It shows that only converting the deflection angle limit into the magnetic field intensity limit, can the operation for digital magnetometer be convenient.%介绍了航空机载产品磁影响测量标准的技术要求和测量方法,深入剖析了磁影响测量的原理,澄清了标准中容易混淆的磁影响限值的确定原则,详细解释了磁强计测量磁影响的方法,经过实践检验,这种磁强计测量航空机载产品磁影响的方法准确可靠。

  10. Mechanical and Thermal Characteristics of Insulation Materials for the KSTAR Magnet System at Cryogenic Temperature

    Science.gov (United States)

    Chung, Wooho; Lim, Bungsu; Kim, Myungkyu; Park, Hyunki; Kim, Keeman; Chu, Yong; Lee, Sangil

    2004-06-01

    The KSTAR(Korea Superconducting Tokamak Advanced Research) superconducting magnet is electrically insulated by the composite material of epoxy resin and glass fiber (2.5 kV/mm) and Kapton (8 kV/mm). The insulation composite material of epoxy resin and glass fiber is prepared using a VPI (Vacuum Pressure Impregnation) process. The superconducting magnet is under mechanical stress caused by the large temperature difference between the operation temperature of the magnet and room temperature. The large electro-magnetic force during the operation of the magnet is also exerted on the magnet. Therefore, the characteristics of the insulation material at cryogenic temperatures are very important and the tensile stress and thermal expansion coefficient for the insulation materials of the KSTAR superconducting magnet are measured. This paper presents results on mechanical properties of the insulation material for KSTAR magnets, such as density, ultimate tensile stress and thermal contraction between room temperature and cryogenic temperatures.

  11. Thermally driven transverse transports and magnetic dynamics on a topological surface capped with a ferromagnet strip

    Science.gov (United States)

    Deng, Ming-Xun; Zhong, Ming; Zheng, Shi-Han; Qiu, Jian-Ming; Yang, Mou; Wang, Rui-Qiang

    2016-02-01

    We theoretically study thermally driven transport of the Dirac fermions on the surface of a topological insulator capped with a ferromagnet strip. The generation and manipulation of anomalous Hall and Nernst effects are analyzed, in which the in-plane magnetization of the ferromagnet film is found to take a decisive role. This scenario is distinct from that modulated by Berry phase where the in-plane magnetization is independent. We further discuss the thermal spin-transfer torque as a backaction of the thermoelectric transports on the magnetization and calculate the dynamics of the anomalous Hall and Nernst effects self-consistently. It is found that the magnitude of the long-time steady Hall and Nernst conductance is determined by competition between the magnetic anisotropy and current-induced effective anisotropy. These results open up a possibility of magnetically controlling the transverse thermoelectric transports or thermally manipulating the magnet switching.

  12. Performance metrics for state-of-the-art airborne magnetic and electromagnetic systems for mapping and detection of unexploded ordnance

    Science.gov (United States)

    Doll, William E.; Bell, David T.; Gamey, T. Jeffrey; Beard, Les P.; Sheehan, Jacob R.; Norton, Jeannemarie

    2010-04-01

    Over the past decade, notable progress has been made in the performance of airborne geophysical systems for mapping and detection of unexploded ordnance in terrestrial and shallow marine environments. For magnetometer systems, the most significant improvements include development of denser magnetometer arrays and vertical gradiometer configurations. In prototype analyses and recent Environmental Security Technology Certification Program (ESTCP) assessments using new production systems the greatest sensitivity has been achieved with a vertical gradiometer configuration, despite model-based survey design results which suggest that dense total-field arrays would be superior. As effective as magnetometer systems have proven to be at many sites, they are inadequate at sites where basalts and other ferrous geologic formations or soils produce anomalies that approach or exceed those of target ordnance items. Additionally, magnetometer systems are ineffective where detection of non-ferrous ordnance items is of primary concern. Recent completion of the Battelle TEM-8 airborne time-domain electromagnetic system represents the culmination of nearly nine years of assessment and development of airborne electromagnetic systems for UXO mapping and detection. A recent ESTCP demonstration of this system in New Mexico showed that it was able to detect 99% of blind-seeded ordnance items, 81mm and larger, and that it could be used to map in detail a bombing target on a basalt flow where previous airborne magnetometer surveys had failed. The probability of detection for the TEM-8 in the blind-seeded study area was better than that reported for a dense-array total-field magnetometer demonstration of the same blind-seeded site, and the TEM-8 system successfully detected these items with less than half as many anomaly picks as the dense-array total-field magnetometer system.

  13. On the probable mechanism of thermal remagnetization of rapidly quenched highly anisotropic magnets

    International Nuclear Information System (INIS)

    Within the framework of the theory of micromagnetism using numerical calculations and the model of a multilayer stochastic system in a unidimensional approximation a study is made into the phenomenon of thermal magnetization of structurally isotropic disperse alloys of high anisotropy magnetic, in particular, of SmCo5 and Nd2Fe14B alloys. The theoretical study shows that the thermal magnetization observed in disperse structurally isotropic rapidly quenched alloys of high anisotropy magnetics can be explained by exchange interaction along crystal boundaries only

  14. The Experimental Analysis on the Thermal and Electrical Characteristics of Impregnating Materials for Superconducting Magnets

    International Nuclear Information System (INIS)

    In recent years, a development of Coated Conductor (CC) that is a called the second generation superconductor tape is opened out. Therefore a commercialization of superconducting power equipments will be realized presently. To realize a commercialization, it is necessary to develop a stable superconducting magnet. A superconducting magnet has to keep thermal stability as well as electrical stability. In this paper, thermal conductivity of impregnating materials, epoxy compounds, was measured at 65K, 77K, 100K and 200K. Dielectric Strength of superconducting magnet modeled electrode system with impregnating materials was also analyzed. Stycast[reg] blue/catalyst 23LV is good materials to apply to the superconducting magnets

  15. Nanopatterning reconfigurable magnetic landscapes via thermally assisted scanning probe lithography

    Science.gov (United States)

    Albisetti, E.; Petti, D.; Pancaldi, M.; Madami, M.; Tacchi, S.; Curtis, J.; King, W. P.; Papp, A.; Csaba, G.; Porod, W.; Vavassori, P.; Riedo, E.; Bertacco, R.

    2016-06-01

    The search for novel tools to control magnetism at the nanoscale is crucial for the development of new paradigms in optics, electronics and spintronics. So far, the fabrication of magnetic nanostructures has been achieved mainly through irreversible structural or chemical modifications. Here, we propose a new concept for creating reconfigurable magnetic nanopatterns by crafting, at the nanoscale, the magnetic anisotropy landscape of a ferromagnetic layer exchange-coupled to an antiferromagnetic layer. By performing localized field cooling with the hot tip of a scanning probe microscope, magnetic structures, with arbitrarily oriented magnetization and tunable unidirectional anisotropy, are reversibly patterned without modifying the film chemistry and topography. This opens unforeseen possibilities for the development of novel metamaterials with finely tuned magnetic properties, such as reconfigurable magneto-plasmonic and magnonic crystals. In this context, we experimentally demonstrate spatially controlled spin wave excitation and propagation in magnetic structures patterned with the proposed method.

  16. Electrical and Thermal Control of Magnetic Exchange Interactions

    OpenAIRE

    Fransson, Jonas; Ren, Jie; Zhu, Jian-Xin

    2014-01-01

    We investigate the far-from-equilibrium nature of magnetic anisotropy and exchange interactions between molecular magnets embedded in a tunnel junction. By mapping to an effective spin model, these magnetic interactions can be divided into three types: isotropic Heisenberg, anisotropic Ising, and anisotropic Dzyaloshinski-Moriya contributions, which are attributed to the background non-equilibrium electronic structures. We further demonstrate that both the magnetic self and exchange interacti...

  17. Magnetization reversal and negative volume thermal expansion in Fe doped Ca2RuO4

    Science.gov (United States)

    Qi, T. F.; Yuan, S. J.; Ye, F.; Chi, S.; Terzic, J.; Zhang, H.; Zhao, Z.; Liu, X.; Parkin, S.; Mao, W. L.; Cao, G.

    We report structural, magnetic, transport and thermal properties of single-crystal Ca2Ru1-xFexO4 (0 pressure, magnetic field and temperature. The central findings of this work are a pronounced magnetization reversal and a negative thermal expansion that are induced by Fe doping. Our results including neutron diffraction data suggest that the magnetization reversal is primarily a result of different temperature dependences of two antiparallel, competing Ru and Fe sublattices and that the negative thermal expansion is achieved via magnetic and metal-insulator transitions. We will present and discuss our results with comparison drawn with relevant systems. This work was supported by the NSF via Grant No. DMR-1265162.

  18. Thermally assisted magnetic switching of a single perpendicularly magnetized layer induced by an in-plane current

    International Nuclear Information System (INIS)

    We report that by heating samples the critical current density for magnetization reversal (Jc) in a single perpendicularly magnetized layer can be decreased from 2.6 × 107 A/cm2 to about 1 × 106 A/cm2 for a temperature increase of 143 K. The nonlinear dependence of Jc on the perpendicular anisotropy field indicates that the coherent magnetic switching model cannot fully explain the current-induced perpendicular switching. By considering the current-induced domain nucleation and expansion during switching, we conclude that Jc also depends on current-induced domain behavior. Moreover, by reversing the heat flow direction, we demonstrate that the thermal related spin transfer torques have little influence on the thermally assisted magnetic switching.

  19. Modifying the growth morphology of aluminum crystals by magnetic mirror in a thermal plasma reactor

    International Nuclear Information System (INIS)

    Effect of magnetic fields on growth morphology of aluminum crystals was studied in a fluidized bed thermal plasma reactor assisted by magnetic mirrors. Aluminum crystals were precipitated in the reactor using aluminum powder or aluminum-graphite mixture as precursors. The absent of magnetic field was also studied for comparison. Products were characterized by scanning electron microscopy (SEM) and X-ray Diffraction (XRD). Results indicated that, regardless the precursor used, it was observed the presence of aluminum nanowires when the external magnetic mirror was applied, suggesting that magnetic fields are able to modify growth morphology at nanoscale

  20. Thermal evolution of magnetic anisotropy of Fe nanoparticles

    International Nuclear Information System (INIS)

    Magnetic properties and the surface morphology of Fe deposited on Pt/Al2O3(1 1 2-bar 0) were in situ studied by magneto-optical Kerr effect (MOKE) and scanning tunneling microscopy (STM), respectively. The surface morphology exhibits that the as-deposited Fe nanoparticels have a narrow sized distribution of diameter around 4.2 nm, revealing the major out-of-plane magnetization. After annealing to 200 deg. C, this out-of-plane magnetization is strongly enhanced while the sized distribution of nanoparticles is almost unchanged. For the further annealing procedure to 400 deg. C, the nanoparticles begin to coalesce into larger ones. Meanwhile, the magnetization reorients from out-of-plane to in-plane direction. Therefore, clear evidence of concurrence for nanoparticles coalescence and magnetization reorientation show that the surface evolution plays an important role on the magnetic transition

  1. Microwaves in Airborne Surveillance

    Directory of Open Access Journals (Sweden)

    S. Christopher

    2013-03-01

    Full Text Available The use of microwave spectrum is widespread due to its convenience. Therefore, enormous amount of information is available in the free space channel. Obviously, mining this channel for surveillance is quite common. Airborne surveillance offers significant advantages in military operations. This paper talks of the usage of microwaves in airborne surveillance systems, in general, and in the Indian airborne early warning and control (AEW&C System, in particular. It brings out the multiple sub-systems onboard the aircraft comprising the AEW&C system and their spectral coverage. Co-location of several systems has its own problems and resolving them in terms of geometric location, frequency band and time of operation are covered. AEW&C, being an airborne system, has several other requirements  including minimal weight, volume and power considerations, lightning protection, streamlining, structural integrity, thermal management, vibration tolerance, corrosion prevention, erosion resistance, static charge discharge capability, bird strike resilience, etc. The methods adopted to cater to all these requirements in the microwave systems that are used in the AEW&C system are discussed. Paper ultimately speaks of the microwave systems that are designed and developed for the Indian AEW&C system to surmount these unusual constraints.Defence Science Journal, 2013, 63(2, pp.138-144, DOI:http://dx.doi.org/10.14429/dsj.63.4255

  2. Thermal stability, thermal expansion and grain-growth in exchange-coupled Fe-Pt-Ag-B bulk nanocomposite magnets

    Energy Technology Data Exchange (ETDEWEB)

    Nicula, R., E-mail: radu.nicula@empa.ch [Empa, Swiss Federal Laboratories for Materials Science and Technology, Advanced Materials Processing, Feuerwerkerstr. 39, CH-3602 Thun (Switzerland); Crisan, O.; Crisan, A.D.; Mercioniu, I. [National Institute for Materials Physics, P.O. Box MG-7, 077125 Bucharest-Magurele (Romania); Stir, M. [University of Berne, Department of Chemistry and Biochemistry, Freiestrasse 3, CH-3012 Berne (Switzerland); Vasiliu, F. [National Institute for Materials Physics, P.O. Box MG-7, 077125 Bucharest-Magurele (Romania)

    2015-02-15

    Highlights: • Formation of the L10 FePt hard-magnetic phase (>90%) directly in the as-cast state. • Specific alternating hard/soft nanostructure is stable to 600 °C without grain growth. • Anisotropic and non-linear thermal expansion effects. • The FePtAgB alloy behaves like a single magnetic phase (full exchange coupling). - Abstract: Rare-earth free (RE-free) exchange coupling nanocomposite magnets are intensively studied nowadays due to their potential use in applications demanding stable high-temperature operation and corrosion resistance. In this respect, the FePt alloy system is one of the most actively addressed potential permanent magnet solutions. In FePt alloys, promising magnetic features arise from the co-existence of hard magnetic L1{sub 0} FePt and soft magnetic L1{sub 2} Fe{sub 3}Pt phases emerged from the same metastable precursor. The present work deals with an in-situ temperature-resolved synchrotron radiation study of the thermal stability, thermal expansion and microstructure evolution in exchange-coupled FePtAgB alloys. The as-cast microstructural state as well as the optimized magnetic behavior are given as reference and correlated to the observed microstructural evolution with temperature. The melt-spun Fe{sub 48}Pt{sub 28}Ag{sub 6}B{sub 18} alloy ribbons were examined in situ by synchrotron X-ray powder diffraction from ambient temperature up to 600 °C. The FePt-Fe{sub 3}Pt exchange-coupled microstructure achieved by rapid solidification is not significantly altered during the high temperature exposure. The thermal expansion of the FePt L1{sub 0} unit cell has been found to be strongly anisotropic, being essentially an in-plane expansion which may be seen as an anisotropic invar effect. For the FePt L1{sub 0} phase, a significant deviation from linear thermal expansion is observed at the Curie temperature T{sub C} = 477 °C. This non-linear behavior above T{sub C} is tentatively linked to a diffusion/segregation mechanism of Ag

  3. Relation between Charpy impact properties and magnetism in thermally aged Fe-Cu model alloys

    International Nuclear Information System (INIS)

    This study demonstrates the possibility of applying magnetic methods to pressure vessel surveillance for irradiation embrittlement at nuclear power plants. Charpy impact test and magnetic hesteresis measurement were preformed on thermally aged Fe-1.0wt%Cu model alloys with and without pre-deformation. DBTT increased with increasing aging time. However, magnetic hysteresis parameters showed nonmonotonical changes. The phenomena are discussed in terms of Cu precipitation behavior and dislocation structure. (author)

  4. Fluctuation, Dissipation, and Entanglement the Classical and Quantum Theory of Thermal Magnetic Noise

    CERN Document Server

    Sidles, J A; Dougherty, W M; Chao Shang Huang

    2000-01-01

    A general theory of thermal magnetic fluctuations near conductive materials is developed; such fluctuations are the magnetic analog of Johnson noise. For realistic experiments in quantum computing and magnetic resonance force microscopy, the predicted relaxation can be rapid enough that substantial experimental care should be taken to minimize it. The same Hamiltonian matrix elements that govern fluctuation and dissipation are shown to also govern entanglement and renormalization, and a specific example of a fluctuation-dissipation-entanglement theorem is constructed.

  5. Thermally-Activated Magnetic Reversal Induced by a Spin-Polarized Current

    OpenAIRE

    Myers, E. B.; Albert, F. J.; Saneky, J. C.; Bonet, E.; Buhrman, R. A.; Ralph, D. C.

    2002-01-01

    We have measured the statistical properties of magnetic reversal in nanomagnets driven by a spin-polarized current. Like reversal induced by a magnetic field, spin-transfer-driven reversal near room temperature exhibits the properties of thermally-activated escape over an effective barrier. However, the spin-transfer effect produces qualitatively different behaviors than an applied magnetic field. We discuss an effective current vs. field phase diagram. If the current and field are tuned so t...

  6. Airborne multispectral and thermal remote sensing for detecting the onset of crop stress caused by multiple factors

    Science.gov (United States)

    Huang, Yanbo; Thomson, Steven J.

    2010-10-01

    Remote sensing technology has been developed and applied to provide spatiotemporal information on crop stress for precision management. A series of multispectral images over a field planted cotton, corn and soybean were obtained by a Geospatial Systems MS4100 camera mounted on an Air Tractor 402B airplane equipped with Camera Link in a Magma converter box triggered by Terraverde Dragonfly® flight navigation and imaging control software. The field crops were intentionally stressed by applying glyphosate herbicide via aircraft and allowing it to drift near-field. Aerial multispectral images in the visible and near-infrared bands were manipulated to produce vegetation indices, which were used to quantify the onset of herbicide induced crop stress. The vegetation indices normalized difference vegetation index (NDVI) and soil adjusted vegetation index (SAVI) showed the ability to monitor crop response to herbicide-induced injury by revealing stress at different phenological stages. Two other fields were managed with irrigated versus nonirrigated treatments, and those fields were imaged with both the multispectral system and an Electrophysics PV-320T thermal imaging camera on board an Air Tractor 402B aircraft. Thermal imagery indicated water stress due to deficits in soil moisture, and a proposed method of determining crop cover percentage using thermal imagery was compared with a multispectral imaging method. Development of an image fusion scheme may be necessary to provide synergy and improve overall water stress detection ability.

  7. Infrared thermography analysis of thermal diffusion induced by RF magnetic field on agar phantoms loaded with magnetic nanoparticles

    Science.gov (United States)

    Bante-Guerra, Jose; Macías, J. D.; Caballero-Aguilar, L.; Vales-Pinzón, C.; Alvarado-Gil, J. J.

    2013-02-01

    Recently, several treatments for fighting malignant tumors have been designed. However these procedures have well known inconveniences, depending on their applicability, tumor size and side effects, among others. Magnetic hyperthermia is a safe, non-invasive method for cancer therapy. This treatment is applied via elevation of target tissue temperature by dissipation of heat from Magnetic Nanoparticles (MNPs), previously located within the tumor. The induction of heat causes cell death and therefore the removal of the tumor. In this work the thermal diffusion in phantoms of agar loaded with magnetic nanoparticles (MNPs) is studied using the infrared thermography technique, which is widely used in biology/medicine (e.g. skin temperature mapping). Agar is one of the materials used to simulate different types of body tissues, these samples are known as "phantoms". Agar is of natural origin, low cost and high degree of biocompatibility. In this work the agar gel was embedded with MNPs by coprecipitation and placed in an alternating magnetic field radiation. As a consequence, the energy from the radiation source is dissipated as heat and then transferred from the MNP to the gel, increasing its temperature. For the temperature analysis, the samples of agar gel were stimulated by RF magnetic field generated by coils. Heating was measured with infrared thermography using a Thermovision A20M infrared camera. Thermographic images allowed obtaining the dependence of thermal diffusion in the phantom as a function of the magnitude of the applied RF magnetic field and the load of magnetic particles.

  8. The Influence of Thermal Evolution in the Magnetic Protection of Terrestrial Planets

    CERN Document Server

    Zuluaga, Jorge I; Cuartas, Pablo A; Hoyos, Jaime H

    2013-01-01

    Magnetic protection of potentially habitable planets plays a central role in determining their actual habitability and/or the chances of detecting atmospheric biosignatures. We develop here a thermal evolution model of potentially habitable Earth-like planets and super-Earths. Using up-to-date dynamo scaling laws we predict the properties of core dynamo magnetic fields and study the influence of thermal evolution on their properties. The level of magnetic protection of tidally locked and unlocked planets is estimated by combining simplified models of the planetary magnetosphere and a phenomenological description of the stellar wind. Thermal evolution introduces a strong dependence of magnetic protection on planetary mass and rotation rate. Tidally locked terrestrial planets with an Earth-like composition would have early dayside magnetospause distances between 1.5 and 4.0 Rp, larger than previously estimated. Unlocked planets with periods of rotation ~1 day are protected by magnetospheres extending between 3 ...

  9. Improvement of radiation resistance of NdFeB magnets by thermal treatment

    International Nuclear Information System (INIS)

    The effect of the thermal stabilization on the radiation sensitivity of neodymium-iron-boron (Nd2Fe14B) undulator magnets to high-energy electron irradiation was investigated. The sample magnets were baked in an oven for 24 hours before irradiation, and the temperatures of this thermal treatment were varied from 142 deg. C to 240 deg. C. All of the thermally stabilized magnets showed higher resistance to irradiation with 2.0 GeV electrons than unbaked sample. Their demagnetization curves decreased linearly with respect to the number of electrons, and with a demagnetization rate remarkably smaller than that of the unbaked magnets. Though, when the stabilizing temperature exceeded some point, the resistance showed small decrease

  10. Electromagnetic, stress and thermal analysis of the Superconducting Magnet

    CERN Document Server

    Ren, Yong

    2015-01-01

    Within the framework of the National Special Project for Magnetic Confined Nuclear Fusion Energy of China, the design of a superconducting magnet project as a test facility of the Nb3Sn coil or NbTi coil for the Chinese Fusion Engineering Test Reactor (CFETR) has been carried out not only to estimate the relevant conductor performance but also to implement a background magnetic field for CFETR CS insert and toroidal field (TF) insert coils. The superconducting magnet is composed of two parts: the inner part with Nb3Sn cable-in-conduit conductor (CICC) and the outer part with NbTi CICC. Both parts are connected in series and powered by a single DC power supply. The superconducting magnet can be cooled with supercritical helium at inlet temperature of 4.5 K. The total inductance and stored energy of the superconducting magnet are about 0.278 H and 436.6 MJ at an operating current of 56 kA respectively. An active quench protection circuit was adopted to transfer the stored magnetic energy of the superconducting ...

  11. Asymmetric magnetic disorder observed in thermally activated magnetization reversal of exchange-biased IrMn/CoFe films

    International Nuclear Information System (INIS)

    We report an asymmetry of magnetic disorder in exchange-biased IrMn(tIrMn=5–20 nm)/CoFe(50 nm) films observed by means of a Kerr microscope, capable of direct domain observation. From the correlation between the magnetization half-reversal time and applied magnetic field, we find that the magnetization switching in all the films occurs via a thermally activated reversal mechanism for both branches of hysteresis loops. Surprisingly, in the forward branch reversal where the applied magnetic field is antiparallel to the direction of exchange-bias field, degree of magnetic disorder decreases as exchange-bias field increases, which is definitely contrasted with the case of backward branch reversal. This result is likely ascribed to the fact that the local values of exchange-bias field and coercive field are oppositely fluctuating with each other in the film. - Highlights: ► Quite different “magnetic disorder” in the same structural-disordered system. ► Elucidation of magnetization reversal mechanism via direct domain observation. ► The simple model which explains the origin of asymmetric magnetic disorder.

  12. Purification of condenser water in thermal power station by superconducting magnetic separation

    International Nuclear Information System (INIS)

    Magnetic separation using cryo-cooled Nb-Ti superconducting magnet was applied for the purification of condenser water. Iron oxides in condenser water were effectively removed by superconducting magnetic separation. The effect of magnetic field strength and filter size was determined. Thermal power station is made up of a steam turbine and a steam condenser which need a lot of water. The water of steam condenser should be replaced, since scales consisting of iron oxide mainly are accumulated on the surface of condenser pipes as it goes. Superconducting high gradient magnetic separation (HGMS) system has merits to remove paramagnetic substance like iron oxides because it can generate higher magnetic field strength than electromagnet or permanent magnet. In this paper, cryo-cooled Nb-Ti superconducting magnet that can generate up to 6 T was used for HGMS systems. Magnetic filters were designed by the analysis of magnetic field distribution at superconducting magnets. The result of X-ray analysis showed contaminants were mostly α-Fe2O3 (hematite) and γ-Fe2O3 (maghemite). The higher magnetic field was applied up to 6 T, the more iron oxides were removed. As the wire diameter of magnetic filter decreased, the turbidity removal of the sample was enhanced.

  13. Purification of condenser water in thermal power station by superconducting magnetic separation

    Energy Technology Data Exchange (ETDEWEB)

    Ha, D.W., E-mail: dwha@keri.re.kr [Korea Electrotechnology Research Institute, Changwon 642-120 (Korea, Republic of); Kwon, J.M.; Baik, S.K.; Lee, Y.J. [Korea Electrotechnology Research Institute, Changwon 642-120 (Korea, Republic of); Han, K.S. [Korea South-East Power Co., Goseong 638-932 (Korea, Republic of); Ko, R.K.; Sohn, M.H.; Seong, K.C. [Korea Electrotechnology Research Institute, Changwon 642-120 (Korea, Republic of)

    2011-11-15

    Magnetic separation using cryo-cooled Nb-Ti superconducting magnet was applied for the purification of condenser water. Iron oxides in condenser water were effectively removed by superconducting magnetic separation. The effect of magnetic field strength and filter size was determined. Thermal power station is made up of a steam turbine and a steam condenser which need a lot of water. The water of steam condenser should be replaced, since scales consisting of iron oxide mainly are accumulated on the surface of condenser pipes as it goes. Superconducting high gradient magnetic separation (HGMS) system has merits to remove paramagnetic substance like iron oxides because it can generate higher magnetic field strength than electromagnet or permanent magnet. In this paper, cryo-cooled Nb-Ti superconducting magnet that can generate up to 6 T was used for HGMS systems. Magnetic filters were designed by the analysis of magnetic field distribution at superconducting magnets. The result of X-ray analysis showed contaminants were mostly {alpha}-Fe{sub 2}O{sub 3} (hematite) and {gamma}-Fe{sub 2}O{sub 3} (maghemite). The higher magnetic field was applied up to 6 T, the more iron oxides were removed. As the wire diameter of magnetic filter decreased, the turbidity removal of the sample was enhanced.

  14. Multifunctional magnetic plasmonic nanoparticles for applications of magnetic/photo-thermal hyperthermia and surface enhanced Raman spectroscopy

    International Nuclear Information System (INIS)

    We prepared magnetic plasmonic nanocomposites, multicore MnFe2O4@SiO2@Ag magnetic nanoparticles (MFA-MNPs). Their magnetic and plasmonic properties were investigated for the applications of hyperthermia and chemical detection. The experiments showed that such nanocomposites could generate heat under the AC magnetic field mainly by the Néel relaxation and are suitable as thermal seeds in magnetic hyperthermia. Moreover, these nanocomposites also possess strong photo-thermal property under near infrared laser light by their properties of surface plasmonic resonance. The measurement of surface enhanced Raman spectroscopy (SERS) spectra exhibited that MFA-MNPs had high sensitivity to rhodamine 6G molecules at concentration of 0.5 ppb. -- Highlights: ► Multicore MnFe2O4@SiO2@Ag nanocomposites were prepared. ► Nanocomposites could generate heat under the AC field mainly by Néel relaxation. ► Nanocomposites showed a strong photo-thermal property under near IR laser light. ► Nanocomposites had high sensitivity to R6G molecules at concentration of 0.5 ppb

  15. Thermal stress dependence of magnetic hysteretic processes in core–shell nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Dumitru, Ioan, E-mail: ioan.dumitru@uaic.ro; Astefanoaei, Iordana; Stancu, Alexandru

    2013-11-20

    The control of thermal stresses in the core–shell structures is an important task in order to understand their temperature dependent magnetization processes. This paper is dedicated to a theoretical and micromagnetic study of the thermal stresses on the hysteretic processes in core–shell nanoparticles. The analytical model can predict the thermal and elastic behavior of the core–shell nanoparticle supposed to a forced cooling process. The temperature and thermal stresses values obtained by direct computation from the analytical model were used to evaluate the magneto-elastic energy of the core–shell system. A micromagnetic model was used to compute the equilibrium positions of the particle magnetization as function of the applied field. The model allows an evaluation of the increase of the particle coercive field and of the blocking temperature as an effect of the thermal stress.

  16. Effect of Magnetic Field on Thermal Instability of Oldroydian Viscoelastic Rotating Fluid in Porous Medium

    Science.gov (United States)

    Thakur, R. C.; Rana, G. C.

    2013-06-01

    In this paper, we investigate the effect of a vertical magnetic field on thermal instability of an Oldroydian visco-elastic rotating fluid in a porous medium. By applying the normal mode analysis method, the dispersion relation governing the effects of rotation, magnetic field and medium permeability is derived and solved analytically and numerically. For the case of stationary convection, the Oldroydian viscoelastic fluid behaves like an ordinary Newtonian fluid and it is observed that rotation has a stabilizing effect while the magnetic field and medium permeability have a stabilizing/destabilizing effect under certain conditions on thermal instability of the Oldroydian viscoelastic fluid in a porous medium. The oscillatory modes are introduced due to the presence of rotation, the magnetic field and gravity field. It is also observed that the `principle of exchange of stability' is invalid in the presence of rotation and the magnetic field.

  17. Thermal chiral vortical and magnetic waves: new excitation modes in chiral fluids

    CERN Document Server

    Kalaydzhyan, Tigran

    2016-01-01

    In certain circumstances, chiral (parity-violating) medium can be described hydrodynamically as a chiral fluid with microscopic quantum anomalies. Possible examples of such systems include strongly coupled quark-gluon plasma, liquid helium 3He-A, neutron stars and the Early Universe. We study first-order hydrodynamics of a chiral fluid on a vortex background and in a external magnetic field. We show that there are two previously undiscovered modes describing heat waves propagating along the vortex and magnetic field. We call them the Thermal Chiral Vortical Wave and Thermal Chiral Magnetic Wave. We also identify known gapless excitations of density, the chiral vortical and chiral magnetic waves. We demonstrate that the velocity of the chiral vortical wave is zero, when the full hydrodynamic framework is applied, and hence the excitation reduces to a charge diffusion mode or is completely absent. We also correct the dispersion relation for the chiral magnetic wave.

  18. Finite temperature quark-gluon vertex with a magnetic field in the Hard Thermal Loop approximation

    CERN Document Server

    Ayala, Alejandro; Loewe, M; Tejeda-Yeomans, Maria Elena; Zamora, R

    2014-01-01

    We compute the thermo-magnetic correction to the quark-gluon vertex in the presence of a weak magnetic field within the Hard Thermal Loop approximation. The vertex satisfies a QED-like Ward identity with the quark self-energy. The only vertex components that get modified are the longitudinal ones. The calculation provides a first principles result for the quark anomalous magnetic moment at high temperature in a weak magnetic field. We extract the effective thermo-magnetic quark-gluon coupling and show that this decreases as a function of the field strength. The result supports the idea that the properties of the effective quark-gluon coupling in the presence of a magnetic field are an important ingredient to understand the inverse magnetic catalysis phenomenon.

  19. Thermal Sensitivity of MD Hematite: Implication for Magnetic Anomalies

    Science.gov (United States)

    Kletetschka, Gunther; Wasilewski, Peter J.; Taylor, Patrick T.

    1999-01-01

    Magnetic remanence of crustal rocks can reside in three common rock-forming magnetic minerals: magnetite, pyrrhotite, and hematite. Thermoremanent magnetization (TRM) of magnetite and pyrrhotite is carried mostly by single domain (SD) grains. The TRM of hematite grains, however, is carried mostly by multidomain (NM) grains. This characteristic is illustrated by TRM acquisition curves for hematite of variable grainsizes. The transition between truly NM behavior and tendency towards SD behavior his been established between hematite grainsizes of 0. 1 and 0.05 mm. Coarse grainsize of lower crustal rocks and the large sensitivity of MD hematite grains to acquire TRM indicates that hematite could be a significant contributor to long-wavelength magnetic anomalies.

  20. Influence of thermal annealing and magnetic field on first order magnetic transition in Pd substituted FeRh

    Energy Technology Data Exchange (ETDEWEB)

    Kushwaha, Pallavi; Lakhani, Archana; Rawat, R; Chaddah, P, E-mail: archnalakhani@csr.ernet.i [UGC-DAE Consortium for Scientific Research University Campus, Khandwa Road Indore-452001, M.P (India)

    2010-01-01

    Influence of successive thermal annealing and magnetic field on First order antiferro (AFM) to ferromagnetic (FM) transition in the Pd substituted FeRh has been studied. With successive thermal annealing CsCl type bcc phase increases at the expense of fct (pseudo fcc) phase. Resistivity measurements do not show any transition in as-cast sample in contrast to annealed samples. AFM to FM transition temperature (T{sub N}) is found to decrease with higher annealing temperature. With the application of magnetic field, T{sub N} shift to lower temperature. These measurements show anomalous thermomagnetic irreversibility besides showing giant magnetoresistance across magnetic field induced first order AFM to FM transition.

  1. Thermal Hydraulic numerical analysis of Fusion superconducting magnet systems

    OpenAIRE

    Kholia, Akshat

    2013-01-01

    In the present scenario, the International Thermonuclear Experimental Reactor (ITER) is in progress and efforts are being made to extend ITER to DEMOnstration Power plant (DEMO) with the purpose to harness the fusion energy for peaceful and constructive purposes. ITER uses the sueperconducting magnet systems for trapping and maneuvering plasma inside the giant tokamak machines. Superconductivity only entails under the critical conditions of temperature, magnetic field and current density. If ...

  2. Influence of pre-existing topography on downflow lava discharge rates estimated from thermal infrared airborne data

    Science.gov (United States)

    Lombardo, V.

    2016-04-01

    Remote sensing thermal data of active lava flows allow the evaluation of effusion rates. This is made possible by a simple formula relating the lava effusion rate to the heat flux radiated per unit time from the surface of the flow. Due to the assumptions of the model, this formula implies that heat flux, surface temperature and lava temperature vary as a function of the flow thickness. These relationships, never verified or validated before, have been used by several authors as a proof of the weakness of the model. Here, multispectral infrared and visible imaging spectrometer (MIVIS) high spatial resolution (5-10 m) thermal data acquired during Etna's 2001 eruption were used to investigate downflow heat flux variations in the lava flow emitted from a vent located at 2100 m a.s.l. A high correlation between the downflow heat flux and the lava flow thickness (measured from a pre-existing digital elevation model) was found. Topography beneath the flow appears to play an important role both in lava emplacement mechanisms and flow dynamics. MIVIS-derived downflow effusion rates are consistent with the law of conservation of mass assessing the reliability of remote sensing techniques.

  3. Heat transfer and thermal fluid calculation of superconducting quadrupole magnet in BEPC II

    International Nuclear Information System (INIS)

    A pair of interaction region superconducting quadrupole (SCQ) magnets in Beijing Electron-Positron Collider Upgrade (BEPC II) are key facilities cooled by liquid helium in the constrained cooling channels. The heat loads to the SCQ magnet and temperature contour of the magnet cryostat are calculated. Based on the calculation, the method to decrease the heat load is presented. The results of thermal fluid modeling for the magnet cryostat are also provided. Two types of cooling schemes, the subcooled liquid helium and the supercritical helium flow, are numerically analyzed. (authors)

  4. Thermal Stability of Large Al-stabilized Superconducting Magnets Theoritical Analysis of CMS Solenoid.

    CERN Document Server

    Juster, F P

    1998-01-01

    The CMS detector magnet presently under design for the future Large Hadron Collider at CERN is an epoxy-impregnated structure, indirectly cooled by two-phase flow liquid helium. This magnet, based on aluminum-stabilized, mechanically reinforced conductor, is not cryostable : the heat generated by a thermal disturbance can be removed only by thermal diffusivity through the windings. In order to study the thermal stability of the magnet, we have developed numerical codes able to predict the thermal behaviour of an anisotropic and non-homogeneous medium against thermal perturbations due to friction or epoxy cracking. Our 3D finite element codes can calculate the propagation or the recovery of a normal zone in a superconducting magnet, taking into account the current diffusion effect, which strongly affects the heat generated by a transition in the case of large Al-stabilized conductors. Two different codes, CASTEM 2000 and HEATING are described in this paper. We present the results of the CMS Solenoid magnet sta...

  5. Pseudo-thermal bar in poorly salted autumnal waters of the Gulf of Finland from satellite-airborne SAR/ASAR/ALSAR survey

    Science.gov (United States)

    Melentyev, Vladimir; Bobylev, Leonid; Tsepelev, Valery; Melentyev, Konstantin; Bednov, Petr

    2010-05-01

    The thermal bar (TB) was disclosed at the end of XIX century by F.A. Forel - world-famed founder of limnology, who studied different processes in Lake Leman from point of view ecology and hydrobiology. Forel supposed that TB arises in temperate large lakes for short period in spring in presence windless calm weather. Well-directed investigations of TB were recommenced in the beginning 1950-s at the Institute of Lake Research Russian Academy of Sciences by Dr A.I. Tikhomirov who had described also specific features of this phenomenon in fall. At the end of 1960-s we began examination thermal and ice regime of fresh and saltish inland water bodies with using remote sensing including multi-spectral airborne-satellite SLR/SAR/ASAR/ALSAR survey. And as result the possibility revealing TB parameters in fall season by low-frequency radar (ALSAR) installed onboard research aircraft was fixed documentally in the Lake Ladoga [Melentyev et. al., 2002]. According to [Tikhomirov, 1959] TB represents convergence zone around temperature of maximum density of fresh water + 4 °C (3, 98 °C, really). This narrow vertical "curtain" appears in littoral in spring owing to heating coastal waters, in fall - due to its cooling. TB divides large lakes and artificial reservoirs on two unequal thermic zones - heat-active (HAZ) and heat-inert (HIZ) that has different stratification of water temperature. Possible existence of TB in poorly salted sea waters was predicted by outstanding Russian oceanographer professor N. Zubov. Obviously firstly it was disclosed but without explanation the physics by [Bychkova, 1987]. Our own sub-satellite studies onboard nuclear icebreaker "Jamal" in western Arctic in fall 1996 allows reveal the TB on saltish waters in north-eastern "corner" of the Yenisei Gulf in mixing zone of marine and river waters. Long-lived converged zone that we call as pseudo-thermal bar (PTB) was marked by stationary banding narrow continuous rough strip that could be destroyed by

  6. Thermo-mechanical analysis of the thermal shield for ITER magnet feeder

    International Nuclear Information System (INIS)

    Highlights: • We model the reasonable finite element model for feeder thermal shield. • We analyze the temperature distribution and pressure drop of the thermal shield. • Different materials for the thermal shield were analyzed. • Thermal stress analysis was performed and analysis result be applied to the detailed design. -- Abstract: The thermal shield for ITER magnet feeder plays the role of preventing thermal radiation from the warm components to the cool superconductor and supercritical helium system. Heat loads were calculated for thermal analysis, then finite element model was established by ANSYS code. Thermal analysis was performed in order to check the temperature distribution and pressure drop of the thermal shield under normal operation state. Different materials (steel or aluminum) for the thermal shield were also checked. Thermal stress analysis was performed based on the results of thermal analyses. Compared analysis results with design criteria, it is demonstrated that the results of the simulation are within allowable design requirements and the design scheme can be applied to the detailed design

  7. Thermo-mechanical analysis of the thermal shield for ITER magnet feeder

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Mingzhun, E-mail: leimz@ipp.ac.cn; Song, Yuntao; Wang, Songke; Wang, Zhongwei; Liu, Sumei; Lu, Kun; Cheng, Yong

    2013-10-15

    Highlights: • We model the reasonable finite element model for feeder thermal shield. • We analyze the temperature distribution and pressure drop of the thermal shield. • Different materials for the thermal shield were analyzed. • Thermal stress analysis was performed and analysis result be applied to the detailed design. -- Abstract: The thermal shield for ITER magnet feeder plays the role of preventing thermal radiation from the warm components to the cool superconductor and supercritical helium system. Heat loads were calculated for thermal analysis, then finite element model was established by ANSYS code. Thermal analysis was performed in order to check the temperature distribution and pressure drop of the thermal shield under normal operation state. Different materials (steel or aluminum) for the thermal shield were also checked. Thermal stress analysis was performed based on the results of thermal analyses. Compared analysis results with design criteria, it is demonstrated that the results of the simulation are within allowable design requirements and the design scheme can be applied to the detailed design.

  8. Fluid mechanical dispersion of airborne pollutants inside urban street canyons subjecting to multi-component ventilation and unstable thermal stratifications.

    Science.gov (United States)

    Mei, Shuo-Jun; Liu, Cheng-Wei; Liu, Di; Zhao, Fu-Yun; Wang, Han-Qing; Li, Xiao-Hong

    2016-09-15

    The pedestrian level pollutant transport in street canyons with multiple aspect ratios (H/W) is numerically investigated in the present work, regarding of various unstable thermal stratification scenarios and plain surrounding. Non-isothermal turbulent wind flow, temperature field and pollutant spread within and above the street canyons are solved by the realizable k-ε turbulence model along with the enhanced wall treatment. One-vortex flow regime is observed for shallow canyons with H/W=0.5, whereas multi-vortex flow regime is observed for deep canyons with H/W=2.0. Both one-vortex and multi-vortex regimes could be observed for the street canyons with H/W=1.0, where the secondary vortex could be initiated by the flow separation and intensified by unstable thermal stratification. Air exchange rate (AER) and pollutant retention time are adopted to respectively evaluate the street canyon ventilation and pollutant removal performance. A second-order polynomial functional relationship is established between AER and Richardson number (Ri). Similar functional relationship could be established between retention time and Ri, and it is only valid for canyons with one-vortex flow regime. In addition, retention time could be prolonged abruptly for canyons with multi-vortex flow regime. Very weak secondary vortex is presented at the ground level of deep canyons with mild stratification, where pollutants are highly accumulated. However, with the decrease of Ri, pollutant concentration adjacent to the ground reduces accordingly. Present research could be applied to guide the urban design and city planning for enhancing pedestrian environment. PMID:27262984

  9. Thermally stable magnetic skyrmions in multilayer synthetic antiferromagnetic racetracks

    Science.gov (United States)

    Zhang, Xichao; Ezawa, Motohiko; Zhou, Yan

    2016-08-01

    A magnetic skyrmion is a topological magnetization structure with a nanometric size and a well-defined swirling spin distribution, which is anticipated to be an essential building block for novel skyrmion-based device applications. We study the motion of magnetic skyrmions in multilayer synthetic antiferromagnetic (SAF) racetracks as well as in conventional monolayer ferromagnetic (FM) racetracks at finite temperature. There is an odd-even effect of the constituent FM layer number on the skyrmion Hall effect (SkHE). Namely, due to the suppression of the SkHE, the magnetic skyrmion has no transverse motion in multilayer SAF racetracks packed with even FM layers. It is shown that a moving magnetic skyrmion is stable even at room temperature (T =300 K) in a bilayer SAF racetrack but it is destructed at T =100 K in a monolayer FM racetrack. Our results indicate that the SAF structures are reliable and promising candidates for future applications in skyrmion electronics and skyrmion spintronics.

  10. High-coercivity, thermally stable and low unblocking temperature magnetic phase: Implications for Archeomagnetic studies

    Science.gov (United States)

    Hartmann, G. A.; Gallet, Y.; Trindade, R. I.; Genevey, A.; Berquo, T. S.; Neumann, R.; Le Goff, M.

    2013-05-01

    The thermoremanent magnetization in baked clay archeological materials provide very useful information on the time evolution of the Earth's magnetic field over the past few millennia. In these materials, a thermally stable magnetic phase characterized by high coercivities (>400 mT) and low unblocking temperatures (~200 degrees Celsius) has recently been recognized in European bricks, tiles, kilns and hearth samples. Both the identification and the origin of this phase remain, however, poorly constrained. The very same high-coercivity, thermally stable, low unblocking temperature (HCSLT) magnetic phase has been identified in Brazilian bricks fragments dated of the past five centuries. We report here a large set of measurements on a selected collection of samples showing variable contributions of the HCSLT phase. These measurements include low-field magnetic susceptibility vs. temperature curves, hysteresis loops, isothermal remanent magnetization (IRM) acquisition, thermal demagnetization of the three-axis IRM, first order reversal curves (FORC), low-temperature magnetization experiments (remanent magnetization curves and alternating current susceptibility), Mössbauer spectroscopy and X-ray diffraction. Results show the coexistence of low-coercivity magnetic minerals (magnetite and titanomagnetite) and high-coercivity minerals (hematite, HCSLT phase and, in some cases, goethite). We note that the HCSLT magnetic phase is always found in association with hematite. We further observe that the Mössbauer spectroscopy, X-ray diffraction spectra, and the FORC diagrams are also very similar to results previously obtained from annealed clays in which nontronite or iron-rich montmorillonite was transformed into Al-substituted hematite by heating. The HCSLT magnetic phase is thus confidently identified as being hematite with Al substitution. Moreover, considering the abundance of montmorillonite in clay mining settings, we suggest that the widespread occurrence of HCSLT in

  11. Thermally actuated magnetization flux pump in single-grain YBCO bulk

    Energy Technology Data Exchange (ETDEWEB)

    Yan Yu; Li Quan; Coombs, T A, E-mail: yy300@cam.ac.u, E-mail: ql229@cam.ac.u, E-mail: tac1000@cam.ac.u [EPEC Superconductivity Group, Electrical Engineering Department, Cambridge University, 9 J J Thomson Avenue, Cambridge CB3 0FA (United Kingdom)

    2009-10-15

    Recent progress in material processing has proved that high temperature superconductors (HTS) have a great potential to trap large magnetic fields at cryogenic temperatures. For example, HTS are widely used in MRI scanners and in magnetic bearings. However, using traditional ways to magnetize, the YBCO will always need the applied field to be as high as the expected field on the superconductor or much higher than it, leading to a much higher cost than that of using permanent magnets. In this paper, we find a method of YBCO magnetization in liquid nitrogen that only requires the applied field to be at the level of a permanent magnet. Moreover, rather than applying a pulsed high current field on the YBCO, we use a thermally actuated material (gadolinium) as an intermedia and create a travelling magnetic field through it by changing the partial temperature so that the partial permeability is changed to build up the magnetization of the YBCO gradually after multiple pumps. The gadolinium bulk is located between the YBCO and the permanent magnet and is heated and cooled repeatedly from the outer surface to generate a travelling thermal wave inwards. In the subsequent experiment, an obvious accumulation of the flux density is detected on the surface of the YBCO bulk.

  12. Thermally actuated magnetization flux pump in single-grain YBCO bulk

    International Nuclear Information System (INIS)

    Recent progress in material processing has proved that high temperature superconductors (HTS) have a great potential to trap large magnetic fields at cryogenic temperatures. For example, HTS are widely used in MRI scanners and in magnetic bearings. However, using traditional ways to magnetize, the YBCO will always need the applied field to be as high as the expected field on the superconductor or much higher than it, leading to a much higher cost than that of using permanent magnets. In this paper, we find a method of YBCO magnetization in liquid nitrogen that only requires the applied field to be at the level of a permanent magnet. Moreover, rather than applying a pulsed high current field on the YBCO, we use a thermally actuated material (gadolinium) as an intermedia and create a travelling magnetic field through it by changing the partial temperature so that the partial permeability is changed to build up the magnetization of the YBCO gradually after multiple pumps. The gadolinium bulk is located between the YBCO and the permanent magnet and is heated and cooled repeatedly from the outer surface to generate a travelling thermal wave inwards. In the subsequent experiment, an obvious accumulation of the flux density is detected on the surface of the YBCO bulk.

  13. Effect of alternate magnetic field on LY12 structure properties after thermal plastic forming

    Institute of Scientific and Technical Information of China (English)

    陈革新; 付宇明; 尹京; 肖宏

    2008-01-01

    The powerful alternate magnetic field treatment is an effective not-heat treatment, which improves the coriaceous performance of the material. In order to reveal the effect rule of the powerful alternate magnetic field on the structure capability after thermal plastic forming, the experimental methods were adopted to compare the microcosmic structure of the LY12 aluminium alloy test pieces before and after the powerful alternate magnetic field treatment. The mechanism of the structure refining was analyzed theoretically. According to the effect rule of the alternate magnetic field on critical grain growth work and the magnetic vibration-constriction mechanism, the structure dynamics factors were analyzed. The results show that, after a certain powerful alternate magnetic field treatment, the mechanical capability of the LY12 aluminium alloy after thermal plastic forming can be reinforced, the structure intertwist deriving from the thermal plastic forming becomes even and the branch crystal is also smashed, consequently refines the structure. The powerful alternate magnetic field treatment can be regarded as an effective method to improve metal structure performance after heat plastic forming.

  14. Magnetic field of Mercury and models of thermal evolution

    International Nuclear Information System (INIS)

    Recent planetary probes have performed in situ measurements of the magnetic fields of all the terrestrial planets. Consideration is given to the origin of these fields, with attention to the equilibrium-- condensation hypothesis for the formation of the solar system. In particular, it is shown that Mercury's present day magnetic field could have been acquired during or shortly after a cold accretion or that it could be due to a presently operating dynamo, resulting from a 'hot evolution'. Two parameters which would help to distinguish between these possibilities are the present-day surface heat flow and the moment of inertia

  15. Magnetic adaptive testing of thermally treated construction steel

    Czech Academy of Sciences Publication Activity Database

    Stupakov, Oleksandr; Skrbek, B.; Tomáš, Ivan

    Amsterdam : IOS Press, 2004 - (Sollier, T.; Prémel, D.; Lesselier, D.), s. 78-81 ISBN 1 58603 407 3. ISSN 1383-7381. - (Studies on Appl. Electromagnetics and Mechanics. 24). [International Workshop on Electromagnetic Nondestructive Evaluation ENDE 2003 /9./. Saclay (FR), 15.05.2003-16.05.2003] R&D Projects: GA ČR(CZ) GA101/02/0236; GA AV ČR(CZ) KSK1010104 Institutional research plan: CEZ:AV0Z1010914 Keywords : magnetic hysteresis * non-destructive testing Subject RIV: BM - Solid Matter Physics ; Magnetism

  16. Seismology of the Sun : Inference of Thermal, Dynamic and Magnetic Field Structures of the Interior

    CERN Document Server

    Hiremath, K M

    2012-01-01

    Recent overwhelming evidences show that the sun strongly influences the Earth's climate and environment. Moreover existence of life on this Earth mainly depends upon the sun's energy. Hence, understanding of physics of the sun, especially the thermal, dynamic and magnetic field structures of its interior, is very important. Recently, from the ground and space based observations, it is discovered that sun oscillates near 5 min periodicity in millions of modes. This discovery heralded a new era in solar physics and a separate branch called helioseismology or seismology of the sun has started. Before the advent of helioseismology, sun's thermal structure of the interior was understood from the evolutionary solution of stellar structure equations that mimicked the present age, mass and radius of the sun. Whereas solution of MHD equations yielded internal dynamics and magnetic field structure of the sun's interior. In this presentation, I review the thermal, dynamic and magnetic field structures of the sun's inter...

  17. Thermal conductivity of magnetic insulators with strong spin-orbit coupling

    Science.gov (United States)

    Stamokostas, Georgios; Lapas, Panteleimon; Fiete, Gregory A.

    We study the influence of spin-orbit coupling on the thermal conductivity of various types of magnetic insulators. In the absence of spin-orbit coupling and orbital-degeneracy, the strong-coupling limit of Hubbard interactions at half filling can often be adequately described in terms of a pure spin Hamiltonian of the Heisenberg form. However, in the presence of spin-orbit coupling the resulting exchange interaction can become highly anisotropic. The effect of the atomic spin-orbit coupling, taken into account through the effect of magnon-phonon interactions and the magnetic order and excitations, on the lattice thermal conductivity of various insulating magnetic systems is studied. We focus on the regime of low temperatures where the dominant source of scattering is two-magnon scattering to one-phonon processes. The thermal current is calculated within the Boltzmann transport theory. We are grateful for financial support from NSF Grant DMR-0955778.

  18. Helioseismic holography of simulated sunspots: magnetic and thermal contributions to travel times

    CERN Document Server

    Felipe, T; Crouch, A D; Birch, A C

    2016-01-01

    Wave propagation through sunspots involves conversion between waves of acoustic and magnetic character. In addition, the thermal structure of sunspots is very different than that of the quiet Sun. As a consequence, the interpretation of local helioseismic measurements of sunspots has long been a challenge. With the aim of understanding these measurements, we carry out numerical simulations of wave propagation through sunspots. Helioseismic holography measurements made from the resulting simulated wavefields show qualitative agreement with observations of real sunspots. We use additional numerical experiments to determine, separately, the influence of the thermal structure of the sunspot and the direct effect of the sunspot magnetic field. We use the ray approximation to show that the travel-time shifts in the thermal (non-magnetic) sunspot model are primarily produced by changes in the wave path due to the Wilson depression rather than variations in the wave speed. This shows that inversions for the subsurfac...

  19. Construction of high current density SC magnets and their thermal stability

    International Nuclear Information System (INIS)

    Pancake type solenoid magnets are constructed which have a similar cooling characteristics to a pulsed dipole magnet for a synchrotron. A metal inpregnated braided cable is used to test a long sample of the cable. The detailed performances of the magnets and cable are examined with respect to achieved fields, training effect and ac losses. The stability theories which have been proposed so far are not adequate to these high current density magnets, so that a new method is developed to estimate the magnet stability. The minimum energy of thermal disturbances (MQE) which causes a quenching is measured by experiment and is compared with the calculation. The calculated values of MQE are in good agreement with the experimental results. The performance of the pancake magnet is discussed on the basis of MQE. (author)

  20. Thermomagnetic writing into magnetophotonic microcavities controlling thermal diffusion for volumetric magnetic holography.

    Science.gov (United States)

    Isogai, Ryosuke; Nakamura, Yuichi; Takagi, Hiroyuki; Goto, Taichi; Lim, Pang Boey; Inoue, Mitsuteru

    2016-01-11

    Holographic memory is expected to become a high-capacity data storage. Magnetic volumetric holograms are rewritable holograms that are recorded as magnetization directions through thermomagnetic recording. However, the effective depth of magnetic holograms is limited by thermal diffusion that causes merging of magnetic fringes. In this study, we propose the insertion of heat-sink layers (HSLs) for retaining well-defined magnetic fringes during volumetric writing. Magnetophotonic microcavity media were used for demonstrating the HSL effect, and the structural design principle was established in numerical calculations. The results indicate that deep and clear magnetic fringes and an improvement in the diffraction efficiency can be achieved by the insertion of HSLs. PMID:26832282

  1. Thermal continuum emission from magnetic rotators in quasars

    Energy Technology Data Exchange (ETDEWEB)

    Sorrell, W.H.

    1981-06-04

    The use of a magnetic rotator model to explain the energy source of quasars is discussed and the composite continuum, calculated using the model, is compared with previously obtained near IR, optical and UV experimental flux data for the quasar 3C273, (U.K.).

  2. Thermal continuum emission from magnetic rotators in quasars

    International Nuclear Information System (INIS)

    The use of a magnetic rotator model to explain the energy source of quasars is discussed and the composite continuum, calculated using the model, is compared with previously obtained near IR, optical and UV experimental flux data for the quasar 3C273, (U.K.)

  3. Rock magnetic properties related to thermal treatment of siderite: Behavior and interpretation

    Science.gov (United States)

    Pan, Yongxin; Zhu, Rixiang; Banerjee, Subir K.; Gill, J.; Williams, Q.

    2000-01-01

    Detailed analyses of rock magnetic experiments were conducted on the oxidation products of high-purity natural crystalline siderite that were thermally treated in air atmosphere. Susceptibilities increase sharply between 400° and 530°C indicative of some new ferrimagnetic mineral phase generation. Both a drop (between 540° and 590°C) on the heating cycle and a dramatic increase (from 590°C to 520°C) on the cooling cycle occurred and are well consistent with the characteristic of magnetite. A distinct Hopkinson-type susceptibility peak indicates that hematite is the terminal product if siderite is heated to 700°C over and over. It has been revealed in detail that the original inverse magnetic susceptibility fabric contributed by the crystalline anisotropy of siderite in siderite-bearing specimens is changed to a normal magnetic fabric during incremental heating over 410°-490°C. This is a result of dominant contributions from the distribution anisotropy of newly transformed ferromagnetic minerals. A strong chemical-viscous remanent magnetization could be produced during siderite oxidation in an external field. Rock magnetic experimental results show that magnetite, maghemite, and hematite are the transformation products of high-temperature oxidation of siderite in air. Maghemite was not completely inverted to hematite even at temperature as high as 690°C during incremental thermal treatments. The mineral transformation processes were confirmed by conventional optical microscopic observation, X-ray diffractometry and Mössbauer spectroscopic analyses. These results indicate that the rock magnetic methods used here are reliable and highly sensitive in detecting very small magnetic phase changes in rocks. We conclude that these temperaturedependent variations of magnetic properties can be used as criteria for identification of siderite in rocks and sediments. Furthermore, it is clear that great care should be exercised in thermal demagnetization of siderite

  4. A search for inverse magnetic catalysis in thermal quark–meson models

    Energy Technology Data Exchange (ETDEWEB)

    Fraga, E.S. [Institute for Theoretical Physics, Goethe University, D-60438 Frankfurt am Main (Germany); Frankfurt Institute for Advanced Studies, Goethe University, D-60438 Frankfurt am Main (Germany); Instituto de Física, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, 21941-972 Rio de Janeiro, RJ (Brazil); Mintz, B.W. [Departamento de Física Teórica, Universidade do Estado do Rio de Janeiro, 20550-013 Rio de Janeiro, RJ (Brazil); Schaffner-Bielich, J. [Institute for Theoretical Physics, Goethe University, D-60438 Frankfurt am Main (Germany)

    2014-04-04

    We explore the parameter space of the two-flavor thermal quark–meson model and its Polyakov loop-extended version under the influence of a constant external magnetic field B. We investigate the behavior of the pseudo critical temperature for chiral symmetry breaking taking into account the likely dependence of two parameters on the magnetic field: the Yukawa quark–meson coupling and the parameter T{sub 0} of the Polyakov loop potential. Under the constraints that magnetic catalysis is realized at zero temperature and the chiral transition at B=0 is a crossover, we find that the quark–meson model leads to thermal magnetic catalysis for the whole allowed parameter space, in contrast to the present picture stemming from lattice QCD.

  5. Thermal and magnetic behavior of Angustifolia Kunth bamboo fibers covered with Fe3O4 particles

    International Nuclear Information System (INIS)

    Several Angustifolia Kunth bamboo fibers, which have been previously treated with an alkaline solution, were coated with magnetite particles. The coating of the fibers was achieved by an in-situ co-precipitation method with Fe2+ and Fe3+in NaOH or NH4OH. The fibers were evaluated by chemical analysis using atomic absorption (A.A.) technique, structural characterization by X-ray diffraction (XRD), thermal stability with thermo-gravimetric analysis (TGA) in nitrogen at temperature range between 23 °C and 800 °C and magnetic behavior using vibrating sample magnetometry (VSM) applying a magnetic field between -27 KOe and 27 KOe at room temperature. We found that the thermal stability and magnetization depend of the synthesis method used to cover the Angustifolia Kunth bamboo fibers. In addition, an improved magnetic response was observed when NaOH solution is used to generate the magnetite coating on the fiber surface.

  6. Magnetic and Thermal Analysis of Current Transformer in Normal and Abnormal Conditions

    Directory of Open Access Journals (Sweden)

    M. B.B. Sharifian

    2008-01-01

    Full Text Available Calculation of Current Transformers (CTs magnetic and thermal properties are very complex due to the complexity of their construction, different properties of their materials and non-linearity of core B-H curve. Finite Element Methods (FEMs are very capable and reliable methods for these problems solution, such as Ansys software. In this study Ansys software is applied in analysis of an 800-400/5-5 CT. These analyses consist of 2D static normal, open circuit and short circuit condition of CT. Magnetic and thermal analysis are made and the results will be discussed.

  7. Combined effect of magnetic field and thermal dispersion on a non-darcy mixed convection

    KAUST Repository

    El-Amin, Mohamed

    2011-05-21

    This paper is devoted to investigate the influences of thermal dispersion and magnetic field on a hot semi-infinite vertical porous plate embedded in a saturated Darcy-Forchheimer-Brinkman porous medium. The coefficient of thermal diffusivity has been assumed to be the sum of the molecular diffusivity and the dynamic diffusivity due to mechanical dispersion. The effects of transverse magnetic field parameter (Hartmann number Ha), Reynolds number Re (different velocities), Prandtl number Pr (different types of fluids) and dispersion parameter on the wall shear stress and the heat transfer rate are discussed. © 2011 Science Press, Institute of Engineering Thermophysics, CAS and Springer-Verlag Berlin Heidelberg.

  8. Fully integrated surface-subsurface flow modelling of groundwater-lake interaction in an esker aquifer: Model verification with stable isotopes and airborne thermal imaging

    Science.gov (United States)

    Ala-aho, Pertti; Rossi, Pekka M.; Isokangas, Elina; Kløve, Bjørn

    2015-03-01

    Water resources management is moving towards integration, where groundwater (GW), surface water (SW) and related aquatic ecosystems are considered one management unit. Because of this paradigm shift, more information and new tools are needed to understand the ecologically relevant fluxes (water, heat, solutes) at the GW-SW interface. This study estimated the magnitude, temporal variability and spatial distribution of water fluxes at the GW-SW interface using a fully integrated hydrological modelling code (HydroGeoSphere). The model domain comprised a hydrologically complex esker aquifer in Northern Finland with interconnected lakes, streams and wetlands. The model was calibrated in steady state for soil hydraulic conductivity and anisotropy and it reproduced the hydraulic head and stream baseflow distribution throughout the aquifer in both transient and steady state modes. In a novel analysis, model outputs were compared with the locations and magnitude of GW discharge to lakes estimated using field techniques. Spatial occurrence of GW-lake interaction was interpreted from airborne thermal infrared imaging. The observed GW inflow locations coincided well with model nodes showing positive exchange flux between surface and subsurface domains. Order of magnitude of simulated GW inflow to lakes showed good agreement with flux values calculated with a stable water isotope technique. Finally, time series of GW inflow, extracted as model output, showed moderate annual variability and demonstrated different interannual inflow changes in seepage and drainage lakes of the aquifer. Overall, this study demonstrated the ability of a fully integrated numerical model to reproduce observed GW-SW exchange processes in a complex unconfined aquifer system. The model-based estimates obtained for GW influx magnitude and spatial distribution, along with information on GW quality can be used to estimate ecologically relevant fluxes in future water resources management.

  9. Estimating the relationship between urban 3D morphology and land surface temperature using airborne LiDAR and Landsat-8 Thermal Infrared Sensor data

    Science.gov (United States)

    Lee, J. H.

    2015-12-01

    Urban forests are known for mitigating the urban heat island effect and heat-related health issues by reducing air and surface temperature. Beyond the amount of the canopy area, however, little is known what kind of spatial patterns and structures of urban forests best contributes to reducing temperatures and mitigating the urban heat effects. Previous studies attempted to find the relationship between the land surface temperature and various indicators of vegetation abundance using remote sensed data but the majority of those studies relied on two dimensional area based metrics, such as tree canopy cover, impervious surface area, and Normalized Differential Vegetation Index, etc. This study investigates the relationship between the three-dimensional spatial structure of urban forests and urban surface temperature focusing on vertical variance. We use a Landsat-8 Thermal Infrared Sensor image (acquired on July 24, 2014) to estimate the land surface temperature of the City of Sacramento, CA. We extract the height and volume of urban features (both vegetation and non-vegetation) using airborne LiDAR (Light Detection and Ranging) and high spatial resolution aerial imagery. Using regression analysis, we apply empirical approach to find the relationship between the land surface temperature and different sets of variables, which describe spatial patterns and structures of various urban features including trees. Our analysis demonstrates that incorporating vertical variance parameters improve the accuracy of the model. The results of the study suggest urban tree planting is an effective and viable solution to mitigate urban heat by increasing the variance of urban surface as well as evaporative cooling effect.

  10. Magnetic and thermal properties of perovskite YFeO{sub 3} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Shen Hui [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); School of Materials Science and Engineering, Shanghai Institute of Technology, Shanghai 200235 (China); Xu Jiayue [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); School of Materials Science and Engineering, Shanghai Institute of Technology, Shanghai 200235 (China)], E-mail: crystalxu@mail.sic.ac.cn; Wu Anhua; Zhao Jingtai; Shi Minli [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)

    2009-02-15

    In this work, we reported the magnetic and thermal properties of perovskite YFeO{sub 3} crystal grown by the floating zone method. YFeO{sub 3} crystal is a canted antiferromagnet with a weak ferromagnetic behavior. The magnetization varied nonlinearly from 0.204 emu/g to 0.173 emu/g at the temperature range of 2-300 K. Its Neel temperature is around 644.5 K. The specific heat is about 0.56 J/(g K) at room temperature and reaches the maximum value of 0.77 J/(g K) at 644.5 K where the antiferromagnetic-paramagnetic transition occurs. Both the lattice and magnetic contributions to the heat capacity have been calculated. Thermal diffusivity and the thermal conductivity are as large as 3.53 mm{sup 2}/s and 11.27 W/(m K) at 298 K, respectively. Both of them show anomalies around the magnetic phase transition point. The average thermal expansion coefficients are -1.72 x 10{sup -6} K{sup -1} and 2.28 x 10{sup -6} K{sup -1} before and after Neel temperature, respectively. The high Neel temperature, high thermal conductivity and small expansion coefficient indicate that YFeO{sub 3} crystal is a promising candidate for laser-induced or optical device applications in broad temperature range and high power system.

  11. Experimental Investigation of Thermal Conductivity and Effusivity of Ferrite Based Nanofluids under Magnetic Field

    OpenAIRE

    Singh, Ashok K.; Vijay S. Raykar

    2013-01-01

    We investigate the effect of magnetic field (H) on the thermal conductivity (λ) and effusivity (ε) of cobalt ferrite based nanofluids having different concentrations (ϕ). Cobalt ferrite nanoparticles (NPs) have been synthesized using the microwave assisted method. At high volume fraction of cobalt ferrite nanoparticles in water (ϕ > 0), both thermal parameters have been found to be suppressed relative to ϕ and λ of water in the absence of H. However, it is seen that percentage values of the e...

  12. Ordering and thermal excitations in dipolar coupled single domain magnet arrays (Presentation Recording)

    Science.gov (United States)

    Östman, Erik; Arnalds, Unnar; Kapaklis, Vassilios; Hjörvarsson, Björgvin

    2015-09-01

    For a small island of a magnetic material the magnetic state of the island is mainly determined by the exchange interaction and the shape anisotropy. Two or more islands placed in close proximity will interact through dipolar interactions. The state of a large system will thus be dictated by interactions at both these length scales. Enabling internal thermal fluctuations, e.g. by the choice of material, of the individual islands allows for the study of thermal ordering in extended nano-patterned magnetic arrays [1,2]. As a result nano-magnetic arrays represent an ideal playground for the study of physical model systems. Here we present three different studies all having used magneto-optical imaging techniques to observe, in real space, the order of the systems. The first study is done on a square lattice of circular islands. The remanent magnetic state of each island is a magnetic vortex structure and we can study the temperature dependence of the vortex nucleation and annihilation fields [3]. The second are long chains of dipolar coupled elongated islands where the magnetization direction in each island only can point in one of two possible directions. This creates a system which in many ways mimics the Ising model [4] and we can relate the correlation length to the temperature. The third one is a spin ice system where elongated islands are placed in a square lattice. Thermal excitations in such systems resemble magnetic monopoles [2] and we can investigate their properties as a function of temperature and lattice parameters. [1] V. Kapaklis et al., New J. Phys. 14, 035009 (2012) [2] V. Kapaklis et al., Nature Nanotech 9, 514(2014) [3] E. Östman et al.,New J. Phys. 16, 053002 (2014) [4] E. Östman et al.,Thermal ordering in mesoscopic Ising chains, In manuscript.

  13. Performance of Nb3Sn quadrupole magnets under localized thermal load

    International Nuclear Information System (INIS)

    This paper describes the results of design and analyses performed on 120-mm Nb3Sn and NbTi quadrupole magnets with parameters relevant for the LHC IR upgrade. A realistic radiation heat load is evaluated in a wide luminosity range and translated into the magnet quench performance. The simulation results are supported by thermal measurements on a 90-mm Nb3Sn quadrupole coil

  14. PERFORMANCE OF NB3SN QUADRUPOLE MAGNETS UNDER LOCALIZED THERMAL LOAD

    International Nuclear Information System (INIS)

    This paper describes the results of design and analyses performed on 120-mm Nb3Sn and NbTi quadrupole magnets with parameters relevant for the LHC IR upgrade. A realistic radiation heat load is evaluated in a wide luminosity range and translated into the magnet quench performance. The simulation results are supported by thermal measurements on a 90-mm Nb3Sn quadrupole coil.

  15. Performance of Nb3Sn quadrupole magnets under localized thermal load

    Energy Technology Data Exchange (ETDEWEB)

    Kashikhin, V.V.; Bossert, r.; Chlachidze, G.; Lamm, M.; Mokhov, N.V.; Novitski, I.; Zlobin, A.V.; /Fermilab

    2009-06-01

    This paper describes the results of design and analyses performed on 120-mm Nb{sub 3}Sn and NbTi quadrupole magnets with parameters relevant for the LHC IR upgrade. A realistic radiation heat load is evaluated in a wide luminosity range and translated into the magnet quench performance. The simulation results are supported by thermal measurements on a 90-mm Nb{sub 3}Sn quadrupole coil.

  16. Realizing exactly solvable SU (N ) magnets with thermal atoms

    Science.gov (United States)

    Beverland, Michael E.; Alagic, Gorjan; Martin, Michael J.; Koller, Andrew P.; Rey, Ana M.; Gorshkov, Alexey V.

    2016-05-01

    We show that n thermal fermionic alkaline-earth-metal atoms in a flat-bottom trap allow one to robustly implement a spin model displaying two symmetries: the Sn symmetry that permutes atoms occupying different vibrational levels of the trap and the SU (N ) symmetry associated with N nuclear spin states. The symmetries make the model exactly solvable, which, in turn, enables the analytic study of dynamical processes such as spin diffusion in this SU (N ) system. We also show how to use this system to generate entangled states that allow for Heisenberg-limited metrology. This highly symmetric spin model should be experimentally realizable even when the vibrational levels are occupied according to a high-temperature thermal or an arbitrary nonthermal distribution.

  17. Radial thermal diffusivity of toroidal plasma affected by resonant magnetic perturbations

    International Nuclear Information System (INIS)

    We investigate how the radial thermal diffusivity of an axisymmetric toroidal plasma is modified by effect of resonant magnetic perturbations (RMPs), using a drift kinetic simulation code for calculating the thermal diffusivity in the perturbed region. The perturbed region is assumed to be generated on and around the resonance surfaces, and is wedged in between the regular closed magnetic surfaces. It has been found that the radial thermal diffusivity χr in the perturbed region is represented as χr = χr(0) {1 + c r parallel2>}. Here r parallel2>1/2 is the strength of the RMPs in the radial directions, means the flux surface average defined by the unperturbed (i.e., original) magnetic field, χr(0) is the neoclassical thermal diffusivity, and c is a positive coefficient. In this paper, dependence of the coefficient c on parameters of the toroidal plasma is studied in results given by the δ f simulation code solving the drift kinetic equation under an assumption of zero electric field. We find that the dependence of c is given as c ∝ ωb/νeff m in the low collisionality regime νeff b, where νeff is the effective collision frequency, ωb is the bounce frequency and m is the particle mass. In case of νeff > ωb, the thermal diffusivity χr evaluated by the simulations becomes close to the neoclassical thermal diffusivity χr(0). (author)

  18. Magnetic evaluation of the hardening and softening of thermally aged iron-copper alloys

    International Nuclear Information System (INIS)

    We evaluated the variations of the magnetic hysteretic behaviour of Fe-1wt%Cu model alloy samples due to thermal aging and over-aging. In these alloys, the formation and growth of Cu-precipitates during the thermal aging process results in mechanical hardening, whereas for aging times higher than a certain critical value, mechanical softening occurs. Magnetic hysteretic properties such as permeability, remanence, peak value and width of the local interaction field distribution, which is related to the Preisach model, are measured as a function of various Cu-precipitation stages obtained by time dependent heat treatments at 773 K (500 deg. C). We found that all magnetic parameters exhibit an extremum value for the peak hardening sample. Furthermore, the variation of permeability, remanence, and the peak value of the local interaction field distribution mimics the behaviour of the reciprocal value of the yield stress as a function of aging time. These results suggest that the magnetic domain wall movement is hindered mainly by Cu-precipitates upon thermal aging. The peak hardening values of the investigated magnetic parameters change by approximately 50% when compared with the initial values. This pronounced sensitivity indicates the potential of magnetic non-destructive evaluation for the assessment of the hardening and softening phenomena induced by Cu-precipitation

  19. 航空重、磁异常相关性分析方法及其应用%CORRELATION ANALYTICAL METHOD AND ITS APPLICATION TO AIRBORNE GRAVITY AND MAGNETIC ANOMALIES

    Institute of Scientific and Technical Information of China (English)

    刘燕戌; 李文勇; 徐剑春

    2012-01-01

    以我国某海域为例,探讨了航空重、磁相关性分析方法及其应用.通过计算航空重、磁相关系数,结合研究区地质特征,将航空重、磁异常划分为三类:即同源异常、半同源异常和非同源异常,分别描述了这三类异常的重、磁特征,推断了异常源性质及地质特征,不仅减少了研究区地质解释的多解性,而且使解释成果更加符合客观实际.%Exemplified by the exploration in a certain sea area in China,the authors discussed the correlation analytical method and its application to airborne gravity and magnetic anomalies. Through computation of the correlation coefficient of airborne gravity and magnetic anomalies in combination with geological characteristics,the authors divided airborne gravity and magnetic anomalies into three types,namely homologous,half homologous and non-homologous anomalies,described these three kinds of anomalies and inferred the features of the source and geological characteristics. The results can not only reduce the multi-solution of geological interpretation but also make the interpretation more in accord with the reality.

  20. Evaluation of SEVIRI Thermal Infra-Red data for airborne dust detection in an arid regions: the UAE case study

    Science.gov (United States)

    Gherboudj, I.; Parajuli, S. P.; Ghedira, H.

    2011-12-01

    Our interest in the study of the dust emission cycle over arid area results from the impacts that they have on the climate and atmospheric processes. Large dust concentration emitted even naturally or anthropogenic may reduce surface insolation by extinction of solar radiation. In addition, the knowledge of its spatio-temporal distribution is essential for monitoring several applications such as solar energy potential and health effect. Satellite-based remote sensing is an efficient tool to improve our understanding of the interaction of the desert dust and surrounding climate over regional and global scales with high frequency measurements. Thermal infrared (TIR) channels (3μm -15μm) of different satellites (MVIRI, AVHRR, MODIS, ADEOS-2/POLDER, TOMS, and MSG/SERIVI) were widely used for dust detection. Several dust detection and forecasting algorithms have been proposed based on these satellite data. However, the spatial and temporal variability of the physical characteristics of dust (concentrations, particle size distribution, location in the atmosphere, and chemical composition) has limited their estimations particularly with the dependence of the dust emission on the wind, soil water content, vegetation, and sediment availability. This study focuses on the analysis of the sensitivity of the MSG/SEVIRI TIR observation to dust generation, surface wind, soil moisture, and surface emissivity over the United Arab Emirates (UAE). SEVIRI observations were acquired in 2009 with temporal and spatial resolutions of 30 minutes and about 3km respectively. While the soil moisture is extracted from the AMSR-E data (1:30 AM and 1:30 PM) at spatial resolution of 25 km, the surface emissivity and Aerosol Optical Thickness were extracted from the MODIS products at spatial resolutions of 1 km and 100 km respectively. In coincidence with the satellites acquisitions, meteorological measurements were collected from seven met stations distributed over the selected study area (wind

  1. Tidal heating of Earth-like exoplanets around M stars: Thermal, magnetic, and orbital evolutions

    OpenAIRE

    Driscoll, P E; Barnes, R.

    2015-01-01

    Abstract The internal thermal and magnetic evolution of rocky exoplanets is critical to their habitability. We focus on the thermal-orbital evolution of Earth-mass planets around low-mass M stars whose radiative habitable zone overlaps with the “tidal zone,” where tidal dissipation is expected to be a significant heat source in the interior. We develop a thermal-orbital evolution model calibrated to Earth that couples tidal dissipation, with a temperature-dependent Maxwell rheology, to orbita...

  2. Estimation of electronic and structural influence on the thermal magnetic properties of clusters

    DEFF Research Database (Denmark)

    Lindgård, P.-A.; Hendriksen, P.V.

    1994-01-01

    Using an effective Heisenberg model for clusters the spin-wave spectrum is calculated by direct diagonalization. The inclusion of a nonuniform magnetization profile at zero temperature, nonuniform exchange interactions as a result of structural relaxations, longer-range interactions, and of...... magnetic surface anisotropy have been studied. Very small effects are found on the thermal magnetic properties relative to those predicted for the simple nearest-neighbor Heisenberg model by Hendriksen, Linderoth, and Lindgard [J. Phys. C 31, 5675 (1993); Phys. Rev. B 48, 7259 (1993)]....

  3. A Reversible Thermally Driven Pump for Use in a Sub-Kelvin Magnetic Refrigerator

    Science.gov (United States)

    Miller, Franklin K.

    2012-01-01

    A document describes a continuous magnetic refrigerator that is suited for cooling astrophysics detectors. This refrigerator has the potential to provide efficient, continuous cooling to temperatures below 50 mK for detectors, and has the benefits over existing magnetic coolers of reduced mass because of faster cycle times, the ability to pump the cooled fluid to remote cooling locations away from the magnetic field created by the superconducting magnet, elimination of the added complexity and mass of heat switches, and elimination of the need for a thermal bus and single crystal paramagnetic materials due to the good thermal contact between the fluid and the paramagnetic material. A reliable, thermodynamically efficient pump that will work at 1.8 K was needed to enable development of the new magnetic refrigerator. The pump consists of two canisters packed with pieces of gadolinium gallium garnet (GGG). The canisters are connected by a superleak (a porous piece of VYCOR glass). A superconducting magnetic coil surrounds each of the canisters. The configuration enables driving of cyclic thermodynamic cycles (such as the sub-Kelvin Active Magnetic Regenerative Refrigerator) without using pistons or moving parts.

  4. Thermal stability conditions of a weakly interacting Fermi gas in a weak magnetic field

    Institute of Scientific and Technical Information of China (English)

    Fudian Men; Hui Liu; Houyu Zhu

    2009-01-01

    On the basis of the results derived from pseudopotential method and ensemble theory,thermal stability of a weakly interacting Fermi gas in a weak magnetic field is studied by using analytical method of thermodynamics.The exact analytical expressions of stability conditions at different temperatures are given,and the effects of interactions as well as magnetic field on the stability of the system are discussed.It is shown that there is an upper-limit magnetic field for the stability of the system at low temperatures,and there is an attractive dividing value at high temperatures.If attractive interaction is lower than the critical value,the stability of the system has no request for magnetic field,but if attractive interaction is higher than the dividing value,a lower-limit magnetic field exists for the stability of the system.

  5. Magnetic and Structural Properties of FePt-FeRh Exchange Spring Films for Thermally Assisted Magnetic Recording Media

    Energy Technology Data Exchange (ETDEWEB)

    Thiele, J.-U. [San Jose Research Center; Maat, S. [San Jose Research Center; Robertson, Lee [ORNL; Fullerton, E. E. [San Jose Research Center

    2004-01-01

    Recently a novel media structure for thermally assisted magnetic recording was proposed consisting of a layer of FePt exchange coupled to a FeRh layer. The FePt forms a high magnetocrystalline anisotropy, high coercivity ferromagnetic layer. The FeRh layer is antiferromagnetic at room temperature, but upon heating above a transition temperature becomes ferromagnetic with a large magnetic moment and low magnetocrystalline anisotropy. The coupled ferromagnetic FePt and FeRh layers form an exchange-spring system significantly lowering the coercive field of the composite system compared to a single layer of FePt. This feature opens intriguing possibilities for media applications for thermally assisted magnetic recording where the ferromagnetic phase of FeRh is exploited to help write the media while the low-temperature antiferromagnetic phase supports the long-term stability. Here temperature-dependent structural and magnetic measurements of undoped and doped FeRh single layer and FePt-FeRh bilayer films are presented and the promises and challenges of the exchange spring media structure are discussed.

  6. Effects of Toroidal Magnetic Fields on the Thermal Instability of Thin Accretion Disks

    Indian Academy of Sciences (India)

    Sheng-Ming Zheng; Feng Yuan; Wei-Min Gu; Ju-Fu Lu

    2011-03-01

    The standard thin disk model predicts that when the accretion rate is moderately high, the disk is radiation–pressure-dominated and thermally unstable. However, observations indicate the opposite, namely the disk is quite stable. We present an explanation in this work by taking into account the role of the magnetic field which was ignored in the previous analysis.

  7. Purification of condenser water in thermal power station by superconducting magnetic separation

    Science.gov (United States)

    Ha, D. W.; Kwon, J. M.; Baik, S. K.; Lee, Y. J.; Han, K. S.; Ko, R. K.; Sohn, M. H.; Seong, K. C.

    2011-11-01

    Thermal power station is made up of a steam turbine and a steam condenser which need a lot of water. The water of steam condenser should be replaced, since scales consisting of iron oxide mainly are accumulated on the surface of condenser pipes as it goes. Superconducting high gradient magnetic separation (HGMS) system has merits to remove paramagnetic substance like iron oxides because it can generate higher magnetic field strength than electromagnet or permanent magnet. In this paper, cryo-cooled Nb-Ti superconducting magnet that can generate up to 6 T was used for HGMS systems. Magnetic filters were designed by the analysis of magnetic field distribution at superconducting magnets. The result of X-ray analysis showed contaminants were mostly α-Fe 2O 3 (hematite) and γ-Fe 2O 3 (maghemite). The higher magnetic field was applied up to 6 T, the more iron oxides were removed. As the wire diameter of magnetic filter decreased, the turbidity removal of the sample was enhanced.

  8. Magnetic and thermal properties of Dy3A15O12 as a magnetic refrigerant

    International Nuclear Information System (INIS)

    We investigated the magnetic entropy of Dy3A15O12 (DAG), which is one of the most promising refrigerants for the Carnot-type magnetic refrigerator. In the present investigation we measured the specific heat in zero magnetic field and the magnetization as a function of temperature and magnetic field, and from the analysis of these experimental results, the magnetic entropy change ΔS /SUB J/ and entropy S are obtained. The values of ΔS /SUB J/ and S of DAG were compared with those of Gd3Ga5O12 (GGG), which is frequently used as a refrigerant for the Carnot-type magnetic refrigerator. The g-factor of the magnetic ion in DAG was shown to play a more important role in determining ΔS /SUB J/ near 20 K than the J-value. It is therefore clear that DAG is a more useful refrigerant than GGG for the Carnot-type refrigerator having a broad temperature span from about20 K to 4.2 K

  9. Thermal expansion anomaly and magnetic properties of Nd2AlFe11Mn5 compound

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Materials with negative thermal expansion have many important applications such as constituents of composite materials designed to .reduce their overall thermal expansion. The structural and magnetic properties of Nd2AlFe11Mn5 compound were investigated by means of X-ray diffraction and magnetization measurements. The result shows that the Nd2AlFe11Mn5 compound crystallizes in a rhomhedral Th2Zn17-type structure. The Curie temperature Tc is about 150 K. The negative thermal expansion coefficient of Nd2AlFe11Mn5 compound is found by X-ray diffraction in temperature range of 122-203 K. There exists an anisotropic and strong positive spontaneous magnetostriction in Nd2AlFe11Mn5 compound. The magnetostriction deformations were discussed.

  10. Utilization of the magnetogranulometric analysis to estimate the thermal conductivity of magnetic fluids

    Science.gov (United States)

    Holotescu, S.; Stoian, F. D.; Marinica, O.; Kubicar, L.; Kopcansky, P.; Timko, M.

    2011-05-01

    In this study, the semi-empirical equation for the effective thermal conductivity of the Holotescu-Stoian model was applied to a set of four dilutions of a transformer oil based magnetic fluid with magnetite nanoparticles as magnetic phase, using the results obtained for the size distributions from the magnetogranulometry analysis, followed by a comparison with the measured values of the effective thermal conductivity obtained by the hot ball method. The link between the size distribution by number and by volume used in the magnetogranulometry analysis and the Holotescu-Stoian model adaptation to the lognormal distribution were presented. The comparison between the results given by the model and the corresponding experimental data showed that by using the approximated size distribution to calculate the effective thermal conductivity the analytical results much closer to the experimental ones are obtained, compared to those given by the Maxwell classical model.

  11. Optically Detected Magnetic Resonance and Thermal Activation Spectroscopy Study of Organic Semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Chang-Hwan Kim

    2003-12-12

    Organic electronic materials are a new class of emerging materials. Organic light emitting devices (OLEDs) are the most promising candidates for future flat panel display technologies. The photophysical characterization is the basic research step one must follow to understand this new class of materials and devices. The light emission properties are closely related to the transport properties of these materials. The objective of this dissertation is to probe the relation between transport and photophysical properties of organic semiconductors. The transport characteristics were evaluated by using thermally stimulated current and thermally stimulated luminescence techniques. The photoluminescence detected magnetic resonance and photoluminescence quantum yield studies provide valuable photophysical information on this class of materials. OLEDs are already in the market. However, detailed studies on the degradation mechanisms are still lacking. Since both optically detected magnetic resonance and thermal activation spectroscopy probe long-lived defect-related states in organic semiconductors, the combined study generates new insight on the OLED operation and degradation mechanisms.

  12. Optically Detected Magnetic Resonance and Thermal Activation Spectroscopy Study of Organic Semiconductors

    International Nuclear Information System (INIS)

    Organic electronic materials are a new class of emerging materials. Organic light emitting devices (OLEDs) are the most promising candidates for future flat panel display technologies. The photophysical characterization is the basic research step one must follow to understand this new class of materials and devices. The light emission properties are closely related to the transport properties of these materials. The objective of this dissertation is to probe the relation between transport and photophysical properties of organic semiconductors. The transport characteristics were evaluated by using thermally stimulated current and thermally stimulated luminescence techniques. The photoluminescence detected magnetic resonance and photoluminescence quantum yield studies provide valuable photophysical information on this class of materials. OLEDs are already in the market. However, detailed studies on the degradation mechanisms are still lacking. Since both optically detected magnetic resonance and thermal activation spectroscopy probe long-lived defect-related states in organic semiconductors, the combined study generates new insight on the OLED operation and degradation mechanisms

  13. Spectral, magnetic, and thermal properties of some thiazolylazo complexes

    Energy Technology Data Exchange (ETDEWEB)

    Masoud, M. S.; Mohamed, G. B.; Abdulrazek, Y. H.; Ali, A. E. [Alexandria Univ., Alexandria (Egypt); Khairy, F. N. [Ahfad Univ. for Women, Omderman (Sudan)

    2002-04-01

    The thiazolylazo compounds and their Co(II), Ni(II) and Cu(II) complexes of barbituric acid, uracil, thiouracil, citrazinic acid, chromotropic acid, gallic acid, pyrogallol and salicylic acid were prepared and characterized by {sup 1}H NMR, IR and the effect of pH on the electronic absorption spectra. The mode of ionization, the electronic transitions and the dissociation constants were discussed. The stoichiometries of the complexed were of 1:1, 2:1 and 3:2 (M:L). The copper complexes are of isotropic ESR spectra (except that of gallic acid which showed a complicated one) and are of magnetically diluted behavior with orbital contribution. Detailed DTA data were obtained and discussed.

  14. Thermal and damping behaviour of magnetic shape memory alloy composites

    Science.gov (United States)

    Glock, Susanne; Michaud, Véronique

    2015-06-01

    Single crystals of ferromagnetic shape memory alloys (MSMA) exhibit magnetic field and stress induced strains via energy dissipating twinning. Embedding single crystalline MSMA particles into a polymer matrix could thus produce composites with enhanced energy dissipation, suitable for damping applications. Composites of ferromagnetic, martensitic or austenitic Ni-Mn-Ga powders embedded in a standard epoxy matrix were produced by casting. The martensitic powder composites showed a crystal structure dependent damping behaviour that was more dissipative than that of austenitic powder or Cu-Ni reference powder composites and than that of the pure matrix. The loss ratio also increased with increasing strain amplitude and decreasing frequency, respectively. Furthermore, Ni-Mn-Ga powder composites exhibited an increased damping behaviour at the martensite/austenite transformation temperature of the Ni-Mn-Ga particles in addition to that at the glass transition temperature of the epoxy matrix, creating possible synergetic effects.

  15. Aerial gamma ray and magnetic survey: Mississippi and Florida airborne survey, Tupelo quadrangle, Mississippi, Alabama, and Tennessee. Final report

    International Nuclear Information System (INIS)

    The Tupelo quadrangle covers a region immediately east of the Mississippi River flood plain in the northernmost Gulf Coastal Physiographic Province. Sediments of Teritary and Paleozoic basins shoal eastward. Tertiary exposures dominate the western half of the quadrangle. Cretaceous strata are exposed over most of the eastern half. A search of available literature revealed no known uranium deposits. A total of eighty-six uranium anomalies were detected and are discussed briefly. Few were considered significant, and most appear to relate to some cultural feature. Magnetic data appears, for the most part, to be in agreement with existing structural interpretations of the region

  16. Aerial gamma ray and magnetic survey: Mississippi and Florida airborne survey, Fort Smith quadrangle, Oklahoma, and Arkansas. Final report

    International Nuclear Information System (INIS)

    The Fort Smith quadrangle in western Arkansas and eastern Oklahoma overlies thick Paleozoic sediments of the Arkoma Basin. These Paleozoics dominate surface exposure except where covered by Quaternary Alluvial materials. Examination of available literature shows no known uranium deposits (or occurrences) within the quadrangle. Seventy-five groups of uranium samples were defined as anomalies and are discussed briefly. None were considered significant, and most appeared to be of cultural origin. Magnetic data show character that suggest structural and/or lithologic complexity, but imply relatively deep-seated sources

  17. Transient electromagnetic simulation and thermal analysis of the DC-biased AC quadrupole magnet for CSNS/RCS

    Institute of Scientific and Technical Information of China (English)

    SUN Xian-Jing; DENG Chang-Dong; KANG Wen

    2012-01-01

    Due to the large cddy currents at the ends of the quadrupole magnets for CSNS/RCS,the magnetic field properties and the heat generation are of great concern.In this paper,we take transient electromagnetic simulation and make use of the eddy current loss from the transient electromagnetic results to perform thermal analysis.Through analysis of the simulated results,the magnetic field dynamic properties of these magnets and a temperature rise are achieved.Finally,the accuracy of the thermal analysis is confirmed by a test of the prototype quadrupole magnet of the RCS.

  18. Transient electromagnetic simulation and thermal analysis of the DC-biased AC quadrupole magnet for CSNS/RCS

    International Nuclear Information System (INIS)

    Due to the large eddy currents at the ends of the quadrupole magnets for CSNS/RCS, the magnetic field properties and the heat generation are of great concern. In this paper, we take transient electromagnetic simulation and make use of the eddy current loss from the transient electromagnetic results to perform thermal analysis. Through analysis of the simulated results, the magnetic field dynamic properties of these magnets and a temperature rise are achieved. Finally, the accuracy of the thermal analysis is confirmed by a test of the prototype quadrupole magnet of the RCS. (authors)

  19. Airborne Sensor Thermal Management Solution

    Energy Technology Data Exchange (ETDEWEB)

    Ng, K. K. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-06-03

    The customer wants to outfit aircraft (de Havilland Twin Otter) with optical sensors. In previous product generations the sensor line-of-sight direction was fixed – the sensor’s direction relied on the orientation of the aircraft. The next generation sensor will be packaged in a rotatable turret so that the line-of-sight is reasonably independent of the aircraft’s orientation. This turret will be mounted on a boom protruding from the side of the aircraft. The customer wants to outfit aircraft (de Havilland Twin Otter) with optical sensors. In previous product generations the sensor line-of-sight direction was fixed – the sensor’s direction relied on the orientation of the aircraft. The next generation sensor will be packaged in a rotatable turret so that the line-of-sight is reasonably independent of the aircraft’s orientation. This turret will be mounted on a boom protruding from the side of the aircraft.

  20. Magnetic Cellulose Nanocrystal Based Anisotropic Polylactic Acid Nanocomposite Films: Influence on Electrical, Magnetic, Thermal, and Mechanical Properties.

    Science.gov (United States)

    Dhar, Prodyut; Kumar, Amit; Katiyar, Vimal

    2016-07-20

    This paper reports a single-step co-precipitation method for the fabrication of magnetic cellulose nanocrystals (MGCNCs) with high iron oxide nanoparticle content (∼51 wt % loading) adsorbed onto cellulose nanocrystals (CNCs). X-ray diffraction (XRD), Fourier transform infrared (FTIR), and Raman spectroscopic studies confirmed that the hydroxyl groups on the surface of CNCs (derived from the bamboo pulp) acted as anchor points for the adsorption of Fe3O4 nanoparticles. The fabricated MGCNCs have a high magnetic moment, which is utilized to orient the magnetoresponsive nanofillers in parallel or perpendicular orientations inside the polylactic acid (PLA) matrix. Magnetic-field-assisted directional alignment of MGCNCs led to the incorporation of anisotropic mechanical, thermal, and electrical properties in the fabricated PLA-MGCNC nanocomposites. Thermomechanical studies showed significant improvement in the elastic modulus and glass-transition temperature for the magnetically oriented samples. Differential scanning calorimetry (DSC) and XRD studies confirmed that the alignment of MGCNCs led to the improvement in the percentage crystallinity and, with the absence of the cold-crystallization phenomenon, finds a potential application in polymer processing in the presence of magnetic field. The tensile strength and percentage elongation for the parallel-oriented samples improved by ∼70 and 240%, respectively, and for perpendicular-oriented samples, by ∼58 and 172%, respectively, in comparison to the unoriented samples. Furthermore, its anisotropically induced electrical and magnetic properties are desirable for fabricating self-biased electronics products. We also demonstrate that the fabricated anisotropic PLA-MGCNC nanocomposites could be laminated into films with the incorporation of directionally tunable mechanical properties. Therefore, the current study provides a novel noninvasive approach of orienting nontoxic bioderived CNCs in the presence of low

  1. Aerial gamma ray and magnetic survey: Mississippi and Florida airborne survey, Helena quadrangle of Arkansas, Mississippi and Tennessee. Final report

    International Nuclear Information System (INIS)

    The Helena quadrangle covers a region largely within the Mississippi River flood plain in the extreme northern Gulf Coastal Province. Tertiary sediments in this area are relatively thick, and overlie a Paleozoic basin gradually shoaling to the northeast. The Oachita Tectonic Zone strikes southeasterly through the center of the quadrangle. The exposed sequence is almost entirely Quaternary sediments of the flood plain area. Older Cenozoic deposits crop out in upland areas on the west side of the river valley. A search of available literature revealed no known uranium deposits. Sixty uranium anomalies were detected and are discussed briefly. None were considered significant, and all appeared to occur as the result of cultural and/or weather effects. Magnetic data appear to be in agreement with existing structural interpretations of the region

  2. Magnetic studies on ZnTe:Cr film grown on glass substrate by thermal evaporation method

    International Nuclear Information System (INIS)

    ZnTe and ZnTe:Cr films were prepared on glass substrate by using thermal evaporation method. X-ray diffraction analysis revealed the presence of ZnCrTe phase. X-ray photoelectron spectroscopy was used to estimate the composition of as-prepared films. The valence state of Cr in ZnTe:Cr film is determined to be +2 by using electron spin resonance spectroscopy. Magnetic moment data as a function of magnetic field was recorded by using superconducting quantum interference device magnetometry at 300 K. The result showed a clear hysteresis loop with coercive field of 48 Oe. Magnetic domains were observed by using magnetic force microscopy and the average value of domain size was 3.7 nm.

  3. A Conduction-Cooled Superconducting Magnet System-Design, Fabrication and Thermal Tests

    DEFF Research Database (Denmark)

    Song, Xiaowei (Andy); Holbøll, Joachim; Wang, Qiuliang;

    2015-01-01

    A conduction-cooled superconducting magnet system with an operating current of 105.5 A was designed, fabricated and tested for material processing applications. The magnet consists of two coaxial NbTi solenoid coils with an identical vertical height of 300 mm and is installed in a high-vacuumed c......A conduction-cooled superconducting magnet system with an operating current of 105.5 A was designed, fabricated and tested for material processing applications. The magnet consists of two coaxial NbTi solenoid coils with an identical vertical height of 300 mm and is installed in a high......-vacuumed cryostat. A two-stage GM cryocooler with a cooling power of 1.5 W at 4.2 K in the second stage is used to cool the system from room temperature to 4.2 K. In this paper, the detailed design, fabrication, thermal analysis and tests of the system are presented....

  4. Thermal Entanglement and Critical Behavior of Magnetic Properties on a Triangulated Kagomé Lattice

    Directory of Open Access Journals (Sweden)

    N. Ananikian

    2011-01-01

    Full Text Available The equilibrium magnetic and entanglement properties in a spin-1/2 Ising-Heisenberg model on a triangulated Kagomé lattice are analyzed by means of the effective field for the Gibbs-Bogoliubov inequality. The calculation is reduced to decoupled individual (clusters trimers due to the separable character of the Ising-type exchange interactions between the Heisenberg trimers. The concurrence in terms of the three qubit isotropic Heisenberg model in the effective Ising field in the absence of a magnetic field is non-zero. The magnetic and entanglement properties exhibit common (plateau, peak features driven by a magnetic field and (antiferromagnetic exchange interaction. The (quantum entangled and non-entangled phases can be exploited as a useful tool for signalling the quantum phase transitions and crossovers at finite temperatures. The critical temperature of order-disorder coincides with the threshold temperature of thermal entanglement.

  5. Thermal equilibrium of non-neutral plasma in dipole magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Sato, N.; Kasaoka, N.; Yoshida, Z. [Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba 277-8561 (Japan)

    2015-04-15

    Self-organization of a long-lived structure is one of the remarkable characteristics of macroscopic systems governed by long-range interactions. In a homogeneous magnetic field, a non-neutral plasma creates a “thermal equilibrium,” which is a Boltzmann distribution on a rigidly rotating frame. Here, we study how a non-neutral plasma self-organizes in inhomogeneous magnetic field; as a typical system, we consider a dipole magnetic field. In this generalized setting, the plasma exhibits its fundamental mechanism that determines the relaxed state. The scale hierarchy of adiabatic invariants is the determinant; the Boltzmann distribution under the topological constraint by the robust adiabatic invariants (hence, the homogeneous distribution with respect to the fragile invariant) is the relevant relaxed state, which turns out to be a rigidly rotating clump of particles (just same as in a homogeneous magnetic field), while the density is no longer homogeneous.

  6. Thermal photon production from gluon fusion induced by magnetic fields in relativistic heavy-ion collisions

    CERN Document Server

    Ayala, Alejandro; Dominguez, C A; Hernandez, L A

    2016-01-01

    We compute the production of thermal photons in relativistic heavy-ion collisions by gluon fusion in the presence of an intense magnetic field, and during the early stages of the reaction. This photon yield is an excess over calculations that do not consider magnetic field effects. We add this excess to recent hydrodynamic calculations that are close to describing the experimental transverse momentum distribution in RHIC and LHC. We then show that with reasonable values for the temperature, magnetic field strength, and strong coupling constant, our results provide a very good description of such excess. These results support the idea that the origin of at least some of the photon excess observed in heavy-ion experiments may arise from magnetic field induced processes.

  7. Magnetic and Thermal Contributions to Helioseismic Travel times in Simulated Sunspots

    Science.gov (United States)

    Braun, Douglas; Felipe, Tobias; Birch, Aaron; Crouch, Ashley D.

    2016-05-01

    The interpretation of local helioseismic measurements of sunspots has long been a challenge, since waves propagating through sunspots are potentially affected by both mode conversion and changes in the thermal structure of the spots. We carry out numerical simulations of wave propagation through a variety of models which alternately isolate either the thermal or magnetic structure of the sunspot or include both of these. We find that helioseismic holography measurements made from the resulting simulated wavefields show qualitative agreement with observations of real sunspots. Using insight from ray theory, we find that travel-time shifts in the thermal (non-magnetic) sunspot model are primarily produced by changes in the wave path due to the Wilson depression rather than variations in the wave speed. This shows that inversions for the subsurface structure of sunspots must account for local changes in the density. In some ranges of horizontal phase speed and frequency there is agreement (within the noise level of the measurements) between the travel times measured in the full magnetic sunspot model and the thermal model. If this conclusion proves to be robust for a wide range of models, it suggests a path towards inversions for sunspot structure. This research has been funded by the Spanish MINECO through grant AYA2014-55078-P, by the NASA Heliophysics Division through NNX14AD42G and NNH12CF23C, and the NSF Solar Terrestrial program through AGS-1127327.

  8. Effect of magnetized phonons on electrical and thermal conductivity of neutron star crust

    Science.gov (United States)

    Baiko, D. A.

    2016-05-01

    We study electrical and thermal conductivities of degenerate electrons emitting and absorbing phonons in a strongly magnetized crystalline neutron star crust. We take into account modification of the phonon spectrum of a Coulomb solid of ions caused by a strong magnetic field. Boltzmann transport equation is solved using a generalized variational method. The ensuing 3D integrals over the transferred momenta are evaluated by two different numerical techniques, the Monte Carlo method and a regular integration over the first Brillouin zone. The results of the two numerical approaches are shown to be in a good agreement. An appreciable growth of electrical and thermal resistivities is reported at quantum and intermediate temperatures T ≲ 0.1Tp (Tp is the ion plasma temperature) in a wide range of chemical compositions and mass densities of matter even for moderately magnetized crystals ωB ˜ ωp (ωB and ωp are the ion cyclotron and plasma frequencies). This effect is due to an appearance of a soft (ω ∝ k2) phonon mode in the magnetized ion Coulomb crystal, which turns out to be easier to excite than acoustic phonons characteristic of the field-free case. These results are important for modelling magneto-thermal evolution of neutron stars.

  9. Super-paramagnetic nanoparticles synthesis in a thermal plasma reactor assisted by magnetic bottle

    Science.gov (United States)

    Cartaya, R.; Puerta, J.; Martín, P.

    2015-03-01

    The present work is a study of the synthesis of super-paramagnetic particles. A preliminary study based on thermodynamic diagrams of Gibbs free energy minimization, was performed with the CSIRO Thermochemical System. In this way, the synthesis of magnetite nanoparticles from precursor powder of ore iron in a thermal reactor, was performed. Then the process was simulated mathematically using magnetohydrodynamic and kinetic equations, in order to predict the synthesis process. A cylindrical reactor assisted by magnetic mirrors was used. The peak intensity of 0.1 tesla (1000 Gauss) was measured at the end of the solenoid. A PlazjetTM 105/15 thermal plasma torch was used. The precursor powder was iron oxide and the plasma gas, nitrogen. The magnetite powder was magnetized whit rare-earth super-magnets, alloy of neodymium-iron boron (NdFeB) grade N-42. The synthesized nanoparticles diameters was measured with a scanning electron microscope LECO and the permanent magnetization with a YOKOGAWA gauss meter, model 325i. Our experimental results show that it is possible the synthesis of super-paramagnetic nanoparticles in thermal plasma reactors.

  10. Experimental investigation on thermal conductivity of MFe{sub 2}O{sub 4} (M = Fe and Co) magnetic nanofluids under influence of magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Karimi, Amir, E-mail: amir.karimi@ut.ac.ir [Department of Mechanical Engineering, College of Engineering, University of Tehran, Tehran 1439955961 (Iran, Islamic Republic of); Afghahi, S. Salman S. [Department of Engineering, Imam Hossein University, Tehran, Iran P.O. Box: 15816-18711 (Iran, Islamic Republic of); Shariatmadar, Hamed; Ashjaee, Mehdi [Department of Mechanical Engineering, College of Engineering, University of Tehran, Tehran 1439955961 (Iran, Islamic Republic of)

    2014-12-20

    Highlights: • A comparative study is conducted to examine thermal conductivity of different MNFs. • Fe{sub 3}O{sub 4} nanoparticles show higher saturation magnetization than that of CoFe{sub 2}O{sub 4}. • New empirical correlations are proposed to predict thermal conductivity of MNFs. - Abstract: In present study, the thermal conductivity of magnetic nanofluids (MNFs) containing MFe{sub 2}O{sub 4} (M = Fe and Co) nanoparticles suspended in deionized water are investigated in the absence and the presence of uniform magnetic field. Fe{sub 3}O{sub 4} and CoFe{sub 2}O{sub 4} nanoparticles are synthesized using the co-precipitation method. The X-ray diffraction, transmission electronic microscopy and vibration sample magnetometer are used to characterize the structure, size and magnetic properties of nanoparticles. The thermal conductivity of MNFs are measured at different volume fractions between 0% and 4.8% and the magnetic field intensity range of 0–500 G. The experimental results show that the thermal conductivity of MNFs increases with increase in volume fraction and magnetic field intensity before reaching its saturation point. Finally, new correlations are presented based on the experimental results to predict thermal conductivity of MNFs in both the absence and the presence of magnetic field.

  11. Experimental investigation on thermal conductivity of MFe2O4 (M = Fe and Co) magnetic nanofluids under influence of magnetic field

    International Nuclear Information System (INIS)

    Highlights: • A comparative study is conducted to examine thermal conductivity of different MNFs. • Fe3O4 nanoparticles show higher saturation magnetization than that of CoFe2O4. • New empirical correlations are proposed to predict thermal conductivity of MNFs. - Abstract: In present study, the thermal conductivity of magnetic nanofluids (MNFs) containing MFe2O4 (M = Fe and Co) nanoparticles suspended in deionized water are investigated in the absence and the presence of uniform magnetic field. Fe3O4 and CoFe2O4 nanoparticles are synthesized using the co-precipitation method. The X-ray diffraction, transmission electronic microscopy and vibration sample magnetometer are used to characterize the structure, size and magnetic properties of nanoparticles. The thermal conductivity of MNFs are measured at different volume fractions between 0% and 4.8% and the magnetic field intensity range of 0–500 G. The experimental results show that the thermal conductivity of MNFs increases with increase in volume fraction and magnetic field intensity before reaching its saturation point. Finally, new correlations are presented based on the experimental results to predict thermal conductivity of MNFs in both the absence and the presence of magnetic field

  12. THE INFLUENCE OF THERMAL EVOLUTION IN THE MAGNETIC PROTECTION OF TERRESTRIAL PLANETS

    Energy Technology Data Exchange (ETDEWEB)

    Zuluaga, Jorge I.; Bustamante, Sebastian; Cuartas, Pablo A. [Instituto de Fisica-FCEN, Universidad de Antioquia, Calle 67 No. 53-108, Medellin (Colombia); Hoyos, Jaime H., E-mail: jzuluaga@fisica.udea.edu.co, E-mail: sbustama@pegasus.udea.edu.co, E-mail: p.cuartas@fisica.udea.edu.co, E-mail: jhhoyos@udem.edu.co [Departamento de Ciencias Basicas, Universidad de Medellin, Carrera 87 No. 30-65, Medellin (Colombia)

    2013-06-10

    Magnetic protection of potentially habitable planets plays a central role in determining their actual habitability and/or the chances of detecting atmospheric biosignatures. Here we develop a thermal evolution model of potentially habitable Earth-like planets and super-Earths (SEs). Using up-to-date dynamo-scaling laws, we predict the properties of core dynamo magnetic fields and study the influence of thermal evolution on their properties. The level of magnetic protection of tidally locked and unlocked planets is estimated by combining simplified models of the planetary magnetosphere and a phenomenological description of the stellar wind. Thermal evolution introduces a strong dependence of magnetic protection on planetary mass and rotation rate. Tidally locked terrestrial planets with an Earth-like composition would have early dayside magnetopause distances between 1.5 and 4.0 R{sub p} , larger than previously estimated. Unlocked planets with periods of rotation {approx}1 day are protected by magnetospheres extending between 3 and 8 R{sub p} . Our results are robust in comparison with variations in planetary bulk composition and uncertainties in other critical model parameters. For illustration purposes, the thermal evolution and magnetic protection of the potentially habitable SEs GL 581d, GJ 667Cc, and HD 40307g were also studied. Assuming an Earth-like composition, we found that the dynamos of these planets are already extinct or close to being shut down. While GL 581d is the best protected, the protection of HD 40307g cannot be reliably estimated. GJ 667Cc, even under optimistic conditions, seems to be severely exposed to the stellar wind, and, under the conditions of our model, has probably suffered massive atmospheric losses.

  13. Rock magnetic finger-printing of soil from a coal-fired thermal power plant.

    Science.gov (United States)

    Gune, Minal; Harshavardhana, B G; Balakrishna, K; Udayashankar, H N; Shankar, R; Manjunatha, B R

    2016-05-01

    We present seasonal rock magnetic data for 48 surficial soil samples collected seasonally around a coal-fired thermal power plant on the southwest coast of India to demonstrate how fly ash from the power plant is transported both spatially and seasonally. Sampling was carried out during pre-monsoon (March), early-monsoon (June), monsoon (September) and post-monsoon (December) seasons. Low- and high-frequency magnetic susceptibility (χlf and χhf), frequency-dependent magnetic susceptibility (χfd), χfd %, isothermal remanent magnetization (IRM), "hard" IRM (HIRM), saturation IRM (SIRM) and inter-parametric ratios were determined for the samples. Scanning electron microscopy (SEM) was used on limited number of samples. NOAA HYSPLIT MODEL backward trajectory analysis and principal component analysis were carried out on the data. Fly ash samples exhibit an average HIRM value (400.07 × 10(-5) Am(2) kg(-1)) that is comparable to that of soil samples. The pre- and post-monsoon samples show a consistent reduction in the concentration of magnetically "hard" minerals with increasing distance from the power plant. These data suggest that fly ash has indeed been transported from the power plant to the sampling locations. Hence, HIRM may perhaps be used as a proxy for tracking fly ash from coal-fired thermal power plants. Seasonal data show that the distribution of fly ash to the surrounding areas is minimum during monsoons. They also point to the dominance of SP magnetite in early-monsoon season, whereas magnetic depletion is documented in the monsoon season. This seasonal difference is attributable to both pedogenesis and anthropogenic activity i.e. operation of the thermal power plant. PMID:27056477

  14. Utilization of the magnetogranulometric analysis to estimate the thermal conductivity of magnetic fluids

    Energy Technology Data Exchange (ETDEWEB)

    Holotescu, S., E-mail: sorin.holotescu@mec.upt.r [Politehnica University of Timisoara, 1 Mihai Viteazu Bv., Timisoara 300222 (Romania); Stoian, F.D.; Marinica, O. [Politehnica University of Timisoara, 1 Mihai Viteazu Bv., Timisoara 300222 (Romania); Kubicar, L. [Institute of Physics, Slovak Academy of Sciences, Dubravska 9, Bratislava (Slovakia); Kopcansky, P.; Timko, M. [Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, Kosice (Slovakia)

    2011-05-15

    In this study, the semi-empirical equation for the effective thermal conductivity of the Holotescu-Stoian model was applied to a set of four dilutions of a transformer oil based magnetic fluid with magnetite nanoparticles as magnetic phase, using the results obtained for the size distributions from the magnetogranulometry analysis, followed by a comparison with the measured values of the effective thermal conductivity obtained by the hot ball method. The link between the size distribution by number and by volume used in the magnetogranulometry analysis and the Holotescu-Stoian model adaptation to the lognormal distribution were presented. The comparison between the results given by the model and the corresponding experimental data showed that by using the approximated size distribution to calculate the effective thermal conductivity the analytical results much closer to the experimental ones are obtained, compared to those given by the Maxwell classical model. - Research Highlights: Utilization of the approximate particle size distribution obtained by magnetogranulometric analysis to evaluate the effective thermal conductivity of a ferrofluid. Presentation of the relationship between the magnetogranulometric method based on the lognormal particle size distribution by volume (Chantrell) and the method based on the lognormal distribution by number (Rasa), highlighting that they give different results. Presentation of a generalized form of the model for evaluating the effective thermal conductivity that includes the particles size distribution.

  15. Thermal analysis and microstructure of hexaperrite based magnet composite with natural rubber matrix

    International Nuclear Information System (INIS)

    Thermal and microstructure analyse of hexa ferrite based on composite magnets with natural rubber matrix have been done to investigate their performance. Such magnets play an important role in the toy and house-hold industries because of their suitable magnetic properties, low cost, lightness and flexibility. The composite magnets were synthesized by blending the ferrite powder and natural rubber at composition 30%-70% rubber volume. The microstructure and thermal behaviour of the composite were examined by using SEM and OTA/TGA. The result show that the natural rubber swelling is optimally at 181,17 oC, which is the recommended top condition for blending. The performance magnet composite is limited by the change of natural rubber properties which decompose at temperature around 400 oC. In the decomposition process, the natural rubber molecule trapped in a composite system based on BaM is more difficult are more compared to the composite system based on SrM because the BaM system particle microstructure and its distribution more homogeneous

  16. Damping Dependence of Reversal Magnetic Field on Co-based Nano-Ferromagnetic with Thermal Activation

    Directory of Open Access Journals (Sweden)

    Nadia Ananda Herianto

    2015-02-01

    Full Text Available Currently, hard disk development has used HAMR technology that applies heat to perpendicular media until near Curie temperature, then cools it down to room temperature. The use of HAMR technology is significantly influence by Gilbert damping constants. Damping affects the magnetization reversal and coercivity field. Simulation is used to evaluate magnetization reversal by completing Landau-Lifshitz-Gilbert explicit equation. A strong ferromagnetic cobalt based material with size 50×50×20 nm3 is used which parameters are anisotropy materials 3.51×106 erg/cm3, magnetic saturation 5697.5 G, exchange constant 1×10-7 erg/cm, and various Gilbert damping from 0.09 to 0.5. To observe the thermal effect, two schemes are used which are Reduced Barrier Writing and Curie Point Writing. As a result, materials with high damping is able to reverse the magnetizations faster and reduce the energy barrier. Moreover, it can lower the minimum field to start the magnetizations reversal, threshold field, and probability rate. The heating near Curie temperature has succeeded in reducing the reversal field to 1/10 compared to writing process in absence of thermal field.

  17. Simulation of adiabatic thermal beams in a periodic solenoidal magnetic focusing field

    OpenAIRE

    Barton, T. J.; Field, David M.; Lang, Kevin M.; Chen, C.

    2012-01-01

    Self-consistent particle-in-cell simulations are performed to verify earlier theoretical predictions of adiabatic thermal beams in a periodic solenoidal magnetic focusing field [ K. R. Samokhvalova, J. Zhou and C. Chen Phys. Plasmas 14 103102 (2007); J. Zhou, K. R. Samokhvalova and C. Chen Phys. Plasmas 15 023102 (2008)]. In particular, results are obtained for adiabatic thermal beams that do not rotate in the Larmor frame. For such beams, the theoretical predictions of the rms beam envelope,...

  18. Thermal and magnetic properties of selected Fe-based metallic glasses

    Directory of Open Access Journals (Sweden)

    R. Nowosielski

    2008-03-01

    Full Text Available Purpose: The work presents a thermal stability characterization and soft magnetic properties analysis of selected Fe-based metallic glasses.Design/methodology/approach: The studies were performed on ribbons prepared by the planar flow casting technique, which is a method of continuous casting of the liquid alloy on a surface of turning copper based wheel. The methods of X-ray diffraction were used for the qualitative phase analysis. The thermal properties associated with crystallization temperature of the glassy alloys were measured using the differential thermal analysis. The magnetic properties were determined by the Maxwell-Wien bridge, fluxometer and VSM methods.Findings: The studied Fe72B20Si4B4 and Fe36Co36B19Si5Nb4 metallic glasses in as-cast state were fully amorphous. The Curie temperature (Tc for Fe72B20Si4B4 alloy has a value of 582 K and Fe36Co36B19Si5Nb4 has higher Tc, which has a value of 605 K. The obtained magnetic properties allow to classify the studied amorphous alloys in as-cast state as soft magnetic materials. The coercive field of tested alloys has a value about 8 A/m. The maximum magnetic permeability of Fe72B20Si4B4 alloy (!max = 21500 is much higher than Fe36Co36B19Si5Nb4 metallic glasses (!max = 3200. Similarly, saturation magnetization of Fe72B20Si4B4 alloy (Bs = 1.04 T is higher than Fe36Co36B19Si5Nb4 (Bs = 0.99 T amorphous alloy.Practical implications: The studied glassy alloys are suitable materials for many electrical application in different elements of magnetic circuits and for manufacturing of sensors and precise current transformers.Originality/value: The obtained results confirm the utility of applied investigation methods in the thermal and magnetic properties analysis of examined amorphous alloys.

  19. Magnetic field and thermal radiation effects on steady hydromagnetic Couette flow through a porous channel

    Directory of Open Access Journals (Sweden)

    Chigozie Israel-Cookey

    2010-09-01

    Full Text Available This paper investigates effects of thermal radiation and magnetic field on hydromagnetic Couette flow of a highly viscous fluid with temperature-dependent viscosity and thermal conductivity at constant pressure through a porous channel. The influence of the channel permeability is also assessed. The relevant governing partial differential equations have been transformed to non-linear coupled ordinary differential equations by virtue of the steady nature of the flow and are solved numerically using a marching finite difference scheme to give approximate solutions for the velocity and temperature profiles. We highlight the effects of Nahme numbers, magnetic field, radiation and permeability parameters on both profiles. The results obtained are used to give graphical illustrations of the distribution of the flow variables and are discussed.

  20. New 2D Thermal Model Applied to an LHC Inner Triplet Quadrupole Magnet

    CERN Document Server

    Bielert, ER; Ten Kate, HHJ; Verweij, AP

    2011-01-01

    A newly developed numerical model is presented that enables to compute two-dimensional heat transfer and temperature distributions over the cross-section of superconducting accelerator magnets. The entire thermal path from strand-in-cable to heat sink, including helium channels is considered. Superfluid helium properties are combined with temperature- and field-dependent non-linear solid material properties. Interfacial interactions are also taken into account. The model is applied to the cross-section of an inner triplet quadrupole magnet featuring a new concept for the ground insulation. Beam loss profiles are implemented as main heat source. It is concluded that operational margins can be considerably increased by opening additional thermal paths, improving the cooling conditions.

  1. Multichannel Magnetorelaxometry In Vivo Monitoring of Magnetic Nanoparticle Quantity for Thermal Ablation Studies

    Science.gov (United States)

    Richter, Heike; Kettering, Melanie; Wiekhorst, Frank; Kosch, Olaf; Hilger, Ingrid; Trahms, Lutz

    2010-12-01

    To inactivate cancer cells with minimal side-effects to the normal tissue, cancer therapy as magnetic thermal ablation utilizes superparamagnetic iron oxide nanoparticles (MNP) injected into the tumor. When exposed to an externally applied alternating magnetic field MNP generate heat, which deactivates cellular processes or even generates lethal thermal doses. Hence, the intratumoral quantity of MNP needs to be thoroughly controlled to govern adequate heat production in the carcinoma region. Here, we investigate the capability of multichannel magnetorelaxometry (MRX) for quantitative measurement of MNP accumulation in the tumor region performed in vivo on a carcinoma mouse, and moreover, the feasibility of quantitative long-term monitoring of MNP amount in a conscious, freely moving mouse.

  2. The JAC airborne EM system : AEM-05

    OpenAIRE

    Levaniemi, H.; Beamish, D; Hautaniemi, H.; Kurimo, M.; Suppala, I.; Vironmaki, J.; Cuss, R.J.; Lahti, M; Tartaras, E.

    2009-01-01

    This paper describes the airborne electromagnetic (AEM) system operated by the Joint Airborne geoscience Capability (JAC), a partnership between the Finnish and British Geological Surveys. The system is a component of a 3-in-1, fixed-wing facility acquiring magnetic gradiometer and full spectrum radiometric data alongside the wing-tip, frequency-domain AEM measurements. The AEM system has recently (2005) been upgraded from 2 to 4 frequencies and now provides a bandwidth from 900 Hz to 25 kHz....

  3. Thermal entanglement in a four-qubit Heisenberg spin model with external magnetic fields

    International Nuclear Information System (INIS)

    The entanglement properties both in the four-qubit anisotropic Heisenberg XY chain with uniform external magnetic fields and in the Heisenberg XX model with two external fields are investigated. The analytical expressions for the measures of entanglement are obtained. In Heisenberg XY chain, the effects of the anisotropy on the thermal entanglement are studied. In the Heisenberg XX ring with two external fields, it is found that a high pair entanglement can be obtained

  4. Thermal entanglement in a four-qubit Heisenberg spin model with external magnetic fields

    Science.gov (United States)

    Wu, Ke-Dong; Zhou, Bin; Cao, Wan-Qiang

    2007-03-01

    The entanglement properties both in the four-qubit anisotropic Heisenberg XY chain with uniform external magnetic fields and in the Heisenberg XX model with two external fields are investigated. The analytical expressions for the measures of entanglement are obtained. In Heisenberg XY chain, the effects of the anisotropy on the thermal entanglement are studied. In the Heisenberg XX ring with two external fields, it is found that a high pair entanglement can be obtained.

  5. Rock magnetic properties across the Paleocene-Eocene Thermal Maximum in Marlborough, New Zealand

    OpenAIRE

    Villasante-Marcos, Víctor; Hollis, Chris; Gerald R. Dickens; Nicolo, Micah J.

    2009-01-01

    Rock magnetic properties have been investigated across the Paleocene-Eocene Thermal Maximum (PETM) in three uplifted sections of Paleogene marine sedimentary rocks in Marlborough, South Island, New Zealand. The sections are exposed along Mead Stream, Dee Stream and Muzzle Stream and represent a depth transect up a continental margin from an upper slope to an outer shelf. Sampling was focused on rock beds previously examined for their biostratigraphy and stable carbon isotope (d13C) compositio...

  6. Thermal transition of ribonuclease a observed using proton nuclear magnetic resonance

    International Nuclear Information System (INIS)

    The thermal transition of bovine pancreatic ribonuclease A (RNase A) was investigated using proton nuclear magnetic resonance (NMR). Significant resonance overlap in the large native protein limits accurate assignments in the 1H NMR spectrum. This study proposes extending the investigation of large proteins by dynamic analysis. Comparison of the traditional method and the correlation coefficient method suggests successful application of spectrum image analysis in dynamic protein studies by NMR

  7. Thermal Stability and Magnetic Properties of Polyvinylidene Fluoride/Magnetite Nanocomposites

    OpenAIRE

    Zen-Wei Ouyang; Erh-Chiang Chen; Tzong-Ming Wu

    2015-01-01

    This work describes the thermal stability and magnetic properties of polyvinylidene fluoride (PVDF)/magnetite nanocomposites fabricated using the solution mixing technique. The image of transmission electron microscopy for PVDF/magnetite nanocomposites reveals that the 13 nm magnetite nanoparticles are well distributed in PVDF matrix. The electroactive β-phase and piezoelectric responses of PVDF/magnetite nanocomposites are increased as the loading of magnetite nanoparticles increases. The pi...

  8. EXPLORING MAGNETIC FIELD STRUCTURE IN STAR-FORMING CORES WITH POLARIZATION OF THERMAL DUST EMISSION

    International Nuclear Information System (INIS)

    The configuration and evolution of the magnetic field in star-forming cores are investigated in order to directly compare simulations and observations. We prepare four different initial clouds having different magnetic field strengths and rotation rates, in which magnetic field lines are aligned/misaligned with the rotation axis. First, we calculate the evolution of such clouds from the prestellar stage until long after protostar formation. Then, we calculate the polarization of thermal dust emission expected from the simulation data. We create polarization maps with arbitrary viewing angles and compare them with observations. Using this procedure, we confirmed that the polarization distribution projected on the celestial plane strongly depends on the viewing angle of the cloud. Thus, by comparing the observations with the polarization map predicted by the simulations, we can roughly determine the angle between the direction of the global magnetic field and the line of sight. The configuration of the polarization vectors also depends on the viewing angle. We find that an hourglass configuration of magnetic field lines is not always realized in a collapsing cloud when the global magnetic field is misaligned with the cloud rotation axis. Depending on the viewing angle, an S-shaped configuration of the magnetic field (or the polarization vectors) appears early in the protostellar accretion phase. This indicates that not only the magnetic field but also the cloud rotation affects the dynamical evolution of such a cloud. In addition, by comparing the simulated polarization with actual observations, we can estimate properties of the host cloud such as the evolutionary stage, magnetic field strength, and rotation rate.

  9. Thermal effect on magnetic parameters of high-coercivity cobalt ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Chagas, E. F., E-mail: efchagas@fisica.ufmt.br; Ponce, A. S.; Prado, R. J.; Silva, G. M. [Instituto de Física, Universidade Federal de Mato Grosso, 78060-900 Cuiabá-MT (Brazil); Bettini, J. [Laboratório Nacional de Nanotecnologia, Centro Nacional de Pesquisa em Energia e Materiais, 13083-970 Campinas (Brazil); Baggio-Saitovitch, E. [Centro Brasileiro de Pesquisas Físicas, Rua Xavier Sigaud 150 Urca. Rio de Janeiro (Brazil)

    2014-07-21

    We prepared very high-coercivity cobalt ferrite nanoparticles synthesized by a combustion method and using short-time high-energy mechanical milling to increase strain and the structural defects density. The coercivity (H{sub C}) of the milled sample reached 3.75 kOe—a value almost five times higher than that obtained for the non-milled material (0.76 kOe). To investigate the effect of the temperature on the magnetic behavior of the milled sample, we performed a thermal treatment on the milled sample at 300, 400, and 600 °C for 30 and 180 min. We analyzed the changes in the magnetic behavior of the nanoparticles due to the thermal treatment using the hysteresis curves, Williamson-Hall analysis, and transmission electron microscopy. The thermal treatment at 600 °C causes decreases in the microstructural strain and density of structural defects resulting in a significant decrease in H{sub C}. Furthermore, this thermal treatment increases the size of the nanoparticles and, as a consequence, there is a substantial increase in the saturation magnetization (M{sub S}). The H{sub C} of the samples treated at 600 °C for 30 and 180 min were 2.24 and 1.93 kOe, respectively, and the M{sub S} of these same samples increased from 57 emu/g to 66 and 70 emu/g, respectively. The H{sub C} and the M{sub S} are less affected by the thermal treatment at 300 and 400 °C.

  10. The effect of thermal treatment, composition and substrate on the texture and magnetic properties of FeCo thin films

    International Nuclear Information System (INIS)

    Magnetostrictive FeCo films (thickness 300 nm) have been produced by RF magnetron sputter deposition. The effects of the substrate, composition and thermal treatment on the structural and magnetic properties of the films have been determined. Structural analysis was performed using transmission electron microscopy and x-ray diffraction. The magnetic properties, including magnetostriction, were determined by the magneto-optical Kerr effect, magnetic force microscopy and strain-modulated ferromagnetic resonance. It is found that the magnetic softness of the films is critically dependent on the texture and strain state of the film. With suitable choices of substrate, composition and thermal treatment, these parameters can be controlled, producing magnetically soft films while maintaining a high magnetostriction. The differential response of the magnetic anisotropy to strain in these films is comparable to the best values achieved by more involved manufacturing processes, such as multilayering, showing excellent potential for their use in magnetic sensors and actuators. (author)

  11. Monte Carlo simulation for thermal assisted reversal process of micro-magnetic torus ring with bistable closure domain structure

    Science.gov (United States)

    Terashima, Kenichi; Suzuki, Kenji; Yamaguchi, Katsuhiko

    2016-04-01

    Monte Carlo simulations were performed for temperature dependences of closure domain parameter for a magnetic micro-torus ring cluster under magnetic field on limited temperature regions. Simulation results show that magnetic field on tiny limited temperature region can reverse magnetic closure domain structures when the magnetic field is applied at a threshold temperature corresponding to intensity of applied magnetic field. This is one of thermally assisted switching phenomena through a self-organization process. The results show the way to find non-wasteful pairs between intensity of magnetic field and temperature region for reversing closure domain structure by temperature dependence of the fluctuation of closure domain parameter. Monte Carlo method for this simulation is very valuable to optimize the design of thermally assisted switching devices.

  12. Controlled synthesis and size-dependent thermal conductivity of Fe3O4 magnetic nanofluids.

    Science.gov (United States)

    Wang, Baodui; Wang, Baogang; Wei, Pengfei; Wang, Xiaobo; Lou, Wenjing

    2012-01-21

    The effect of nanoparticle size (4~44 nm) on the thermal conductivities of heat transfer oils has been systematically examined using iron oxide nanoparticles. Such Fe(3)O(4) nanoparticles were synthesized by a simple one-pot pyrolysis method. The size (16~44 nm), shape and assembly patterns of monodisperse Fe(3)O(4) nanoparticles were modulated by only controlling the amount of Fe(acac)(3). After the as-prepared Fe(3)O(4) NPs were dispersed in heat transfer oils, the prepared magnetic nanofluids exhibit higher thermal conductivity than heat transfer oils, and the enhanced values increase with a decrease in particle size. In addition, the viscosities of all nanofliuids are remarkably lower than that of the base fluid, which has been found for the first time in the nanofluid field. The promising features offer potential application in thermal energy engineering. PMID:22086086

  13. Thermally activated phase slips in superfluid spin transport in magnetic wires

    Science.gov (United States)

    Kim, Se Kwon; Takei, So; Tserkovnyak, Yaroslav

    2016-01-01

    We theoretically study thermally activated phase slips in superfluid spin transport in easy-plane magnetic wires within the stochastic Landau-Lifshitz-Gilbert phenomenology, which runs parallel to the Langer-Ambegaokar-McCumber-Halperin theory for thermal resistances in superconducting wires. To that end, we start by obtaining the exact solutions for free-energy minima and saddle points. We provide an analytical expression for the phase-slip rate in the zero spin-current limit, which involves a detailed analysis of spin fluctuations at the extrema of the free energy. An experimental setup for a magnetoelectric circuit is proposed, in which thermal phase slips can be inferred by measuring nonlocal magnetoresistance.

  14. The thermal instability in a sheared magnetic field - Filament condensation with anisotropic heat conduction. [solar physics

    Science.gov (United States)

    Van Hoven, G.; Mok, Y.

    1984-01-01

    The condensation-mode growth rate of the thermal instability in an empirically motivated sheared field is shown to depend upon the existence of perpendicular thermal conduction. This typically very small effect (perpendicular conductivity/parallel conductivity less than about 10 to the -10th for the solar corona) increases the spatial-derivative order of the compressible temperature-perturbation equation, and thereby eliminates the singularities which appear when perpendicular conductivity = 0. The resulting growth rate is less than 1.5 times the controlling constant-density radiation rate, and has a clear maximum at a cross-field length of order 100 times and a width of about 0.1 the magnetic shear scale for solar conditions. The profiles of the observable temperature and density perturbations are independent of the thermal conductivity, and thus agree with those found previously. An analytic solution to the short-wavelength incompressible case is also given.

  15. Thermal Model and Optimization of a Large Crystal Detector using a Metallic Magnetic Calorimeter

    CERN Document Server

    Kim, G B; Jang, Y S; Kim, H J; Kim, Y H; Kobychev, V V; Lee, H J; Lee, J H; Lee, J Y; Lee, M K; Lee, S J; Yoon, W S

    2014-01-01

    We established a simple thermal model of the heat flow in a large crystal detector designed for a neutrinoless double beta decay experiment. The detector is composed of a CaMoO$_{4}$ crystal and a metallic magnetic calorimeter (MMC). The thermal connection between the absorber and the sensor consists of a gold film evaporated on the crystal surface and gold bonding wires attached to this film and the MMC sensor. The model describes athermal and thermal processes of heat flow to the gold film. A successive experiment based on optimization calculations of the area and thickness of the gold film showed a significant improvement in the size and rise-time of the measured signals.

  16. Calculation of the Thermal Footprint of Resonant Magnetic Perturbations in DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    Joseph, I; Evans, T; Moyer, R; Fenstermacher, M; Groth, M; Kasilov, S; Lasnier, C; Porter, G; Runov, A; Schaffer, M; Schneider, R; Watkins, J

    2007-09-14

    The effect of resonant magnetic perturbations on heat transport in DIII-D H-mode plasmas has been calculated by combining the TRIP3D field-line tracing code with the E3D two-fluid transport code. Simulations show that the divertor heat flux distribution becomes non-axisymmetric because heat flux is efficiently guided to the divertor along the three-dimensional invariant manifolds of the magnetic field. Calculations demonstrate that heat flux is spread over a wider area of the divertor target, thereby reducing the peak heat flux delivered during steady-state operation. Filtered optical cameras have observed non-axisymmetric particle fluxes at the strike-point and Langmuir probes have observed non-axisymmetric floating potentials. On the other hand, the predicted magnitude of stochastic thermal transport is too large to match the pedestal plasma profiles measured by Thomson scattering and charge exchange recombination spectroscopy. The Braginskii thermal conductivity overestimates the expected heat transport in the pedestal because the mean free path is longer than estimates of the parallel thermal correlation length, and collisionless transport models are probably required for accurate description. However, even the collisionless estimates for electron thermal transport are too large by one to two orders of magnitude. Thus, it is likely that another mechanism such as rotational screening of resonant perturbations limits the stochastic region and reduces transport inside of the pedestal.

  17. Generation of a symmetric magnetic field by thermal convection in a plane rotating layer

    CERN Document Server

    Zheligovsky, V

    2010-01-01

    We investigate numerically magnetic field generation by thermal convection with square periodicity cells in a rotating horizontal layer of electrically-conducting fluid with stress-free electrically perfectly conducting boundaries for Rayleigh numbers in the interval 5100\\le R\\le 5800. Dynamos of three kinds, apparently not encountered before, are presented: 1) Steady and time-periodic regimes, where the flow and magnetic field are symmetric about a vertical axis. In regimes with this symmetry, the global alpha-effect is insignificant, and the complex structure of the system of amplitude equations controlling weakly nonlinear stability of the system to perturbations with large spatial and temporal scales suggests that the perturbations are likely to exhibit uncommon complex patterns of behaviour, to be studied in the future work. 2) Periodic in time regimes, where magnetic field is always concentrated in the interior of the convective layer, in contrast to the behaviour first observed by St Pierre (1993) and ...

  18. Thermal Analysis on Radial Flux Permanent Magnet Generator (PMG using Finite Element Method

    Directory of Open Access Journals (Sweden)

    Hilman Syaeful A Syaeful A

    2011-05-01

    Full Text Available The main source of heat in the permanent magnet generator (PMG is the total losses which f come from winding losses, core losses and rotational losses. Total heat arising from such these losses must be properly distributed and maintained so as not to exceed the maximum allowable temperature to prevent damage to insulation on the winding and demagnetization on the permanent magnet machines. In this research, we consider thermal analysis which is occurred on the radial flux PMG by using finite element method to determine the extent to which the heat generated can be properly distributed. The simulation results show that there are no points of heat concentration or hot spot. The simulation maximum temperatures of the permanent magnet and the winding are 39.1oC and 72.5oC respectively while the experimental maximum temperature of the winding is 62oC.

  19. Parker/buoyancy instabilities with anisotropic thermal conduction, cosmic rays, and arbitrary magnetic field strength

    CERN Document Server

    Dennis, Timothy J

    2008-01-01

    We report the results of a local stability analysis for a magnetized, gravitationally stratified plasma containing cosmic rays. We account for cosmic-ray diffusion and thermal conduction parallel to the magnetic field and allow beta to take any value, where p is the plasma pressure and B is the magnetic field strength. We take the gravitational acceleration to be in the -z-direction and the equilibrium magnetic field to be in the y-direction, and we derive the dispersion relation for small-amplitude instabilities and waves in the large-|k_x| limit. We use the Routh-Hurwitz criterion to show analytically that the necessary and sufficient criterion for stability in this limit is n k_B dT/dz + dp_cr/dz + (1/8pi)dB^2/dz > 0, where T is the temperature, n is the number density of thermal particles, and p_cr is the cosmic-ray pressure. We present approximate analytical solutions for the normal modes in the low- and high-diffusivity limits, show that they are consistent with the derived stability criterion, and comp...

  20. Methotrexate conjugated magnetic nanoparticle for targeted drug delivery and thermal therapy

    Science.gov (United States)

    Gupta, Jagriti; Bhargava, Parag; Bahadur, D.

    2014-05-01

    A simple soft chemical approach is used for the preparation of citrate functionalized iron oxide (Fe3O4) aqueous colloidal magnetic nanoparticles (CA-MNPs) of average size ˜10 nm. The CA-MNPs exhibit superparamagnetic behavior at room temperature with strong field dependent magnetic responsivity. The CA-MNPs can be conjugated with Methotrexate (MTX) drug through amide bonds between the carboxylic group on the surface of MNPs and amine group of MTX. The surface functionalization of Fe3O4 nanoparticles with citric acid and conjugation of MTX drug is evident from FTIR spectroscopy, zeta-potential measurement, and elemental and thermal analyses. From the drug release study, it has been observed that this bonding of MTX conjugated MNPs (MTX-MNPs) is cleaved by the intracellular enzymes in lysosome, and MTX is delivered largely inside target cancerous cells at lower pH, thereby reducing toxicity to normal cells. Also, it has been observed that the intercellular uptake of MTX-MNPs is higher compared to CA-MNPs. In addition, the aqueous colloidal stability, optimal magnetization, and good specific absorption rate (under external AC magnetic field) of CA-MNPs act as effective heating source for thermal therapy. Cytotoxicity study of MTX-MNPs shows the reduction of cellular viability for human cervical cancer cells (HeLa). Further, a synergistic effect of MTX-MNPs shows a more effective tumor cell death due to the combined effect of thermo-chemotherapy.

  1. Analysis of phase separation by thermal aging in duplex stainless steels by magnetic methods

    International Nuclear Information System (INIS)

    The phase separation in ferrite phase of duplex stainless steel is the primary cause of thermal aging embrittlement of the LWR primary pressure boundary components. In this study the phase separation of simulated duplex stainless steel was detected by Mossbauer spectroscopy and magnetic property analysis by VSM (Vibrating Specimen Magnetometer). The simulated duplex stainless steels, Fe-Cr binary, Fe-Cr-Ni Temary, and Fe-Cr-Ni-Si quaternary alloys, were aged at 370 and 400 deg C up to 5,340 hours. It was observed from Mossbauer spectra analysis that internal magnetic field increases with aging time and from VSM that the specific saturation magnetization and Curie temperature increase with aging time. These results are indicative that phase separation into Fe-rich region and Cr-rich region is caused by thermal aging in the temperature range of 370 - 400 deg C. In cases specimens containing Ni, the increase of specific saturation magnetization is much higher. This implies that Ni seems to promote Fe-Cr interdiffusion, which accelerates the phase separation into Fe-rich α phase and Cr-rich α' phase. (author)

  2. Model atmospheres and radiation of magnetic neutron stars: Anisotropic thermal emission

    Science.gov (United States)

    Pavlov, G. G.; Shibanov, Yu. A.; Ventura, J.; Zavlin, V. E.

    1994-01-01

    We investigate the anisotropy of the thermal radiation emitted by a surface element of a neutron star atmosphere (e.g., by a polar cap of a radio pulsar). Angular dependences of the partial fluxes at various photon energies, and spectra at various angles are obtained for different values of the effective temperature T(sub eff) and magnetic field strength B, and for different directions of the magnetic field. It is shown that the local radiation of the magnetized neutron star atmospheres is highly anisotropic, with the maximum flux emitted in the magnetic field direction. At high B the angular dependences in the soft X-ray range have two maxima, a high narrow peak along B and a lower and broader maximum at intermediate angles. The radiation is strongly polarized, the modulation of the degree of polarization due to the rotation of the neurtron star may be much higher than that for the radiative flux. The results obtained are compared with recent ROSAT observations of the thermal-like radiation from the radio pulsars PSR 1929+10 and PSR J0437-4715.

  3. THERMAL EQUILIBRIA OF OPTICALLY THIN, MAGNETICALLY SUPPORTED, TWO-TEMPERATURE, BLACK HOLE ACCRETION DISKS

    International Nuclear Information System (INIS)

    We obtained thermal equilibrium solutions for optically thin, two-temperature black hole accretion disks incorporating magnetic fields. The main objective of this study is to explain the bright/hard state observed during the bright/slow transition of galactic black hole candidates. We assume that the energy transfer from ions to electrons occurs via Coulomb collisions. Bremsstrahlung, synchrotron, and inverse Compton scattering are considered as the radiative cooling processes. In order to complete the set of basic equations, we specify the magnetic flux advection rate instead of β = pgas/pmag. We find magnetically supported (low-β), thermally stable solutions. In these solutions, the total amount of the heating via the dissipation of turbulent magnetic fields goes into electrons and balances the radiative cooling. The low-β solutions extend to high mass accretion rates (∼>α2M-dotEdd) and the electron temperature is moderately cool (Te ∼ 108-109.5 K). High luminosities (∼>0.1LEdd) and moderately high energy cutoffs in the X-ray spectrum (∼50-200 keV) observed in the bright/hard state can be explained by the low-β solutions.

  4. Effects of thermal annealing on the magnetic interactions in nanogranular Fe-Ag thin films

    Energy Technology Data Exchange (ETDEWEB)

    Alonso, J.; Fdez-Gubieda, M.L.; Svalov, A. [Departamento de Electricidad y Electronica, Universidad del Pais Vasco (UPV/EHU), Campus de Leioa, 48940 Leioa (Spain); Meneghini, C. [Dipartimento di Fisica ' E. Amaldi' , Universita degli Studi Roma Tre, 00146 Roma (Italy); Orue, I. [SGIker, Universidad del Pais Vasco (UPV/EHU), Campus de Leioa, 48940 Leioa (Spain)

    2012-09-25

    Highlights: Black-Right-Pointing-Pointer Fe{sub x}Ag{sub 100-x} granular thin films with competing interactions (25 {<=} x{<=} 35). Black-Right-Pointing-Pointer Annealing up to 200 Degree-Sign C mainly modifies the interface of Fe nanoparticles. Black-Right-Pointing-Pointer Annealing reduces RKKY interactions in Fe{sub 25}Ag{sub 75}. Black-Right-Pointing-Pointer Annealing favors exchange interactions and ferromagnetic order in Fe{sub 35}Ag{sub 65}. - Abstract: In this paper we have studied, by analysing the evolution of the magnetic behaviour during thermal treatment, the role of the interparticle magnetic interactions in Fe{sub x}Ag{sub 100-x} granular thin films prepared by sputtering deposition technique. Two compositions have been selected: x = 25 and 35, below and around the magnetic percolation of the system, respectively, according to our previous works. The structure of these thin films has been studied by X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) measurements. To analyse the magnetic behaviour, DC magnetic measurements have been carried out after progressively annealing the samples at different temperatures (0 {<=} T{sub ann} {<=} 200 Degree-Sign C). These measurements have revealed that, upon thermal treatment, the frustrated state at low temperatures (T < 80 K) for the x = 25 sample tends to disappear, probably due to the weakening of RKKY interactions after the segregation of soluted Fe atoms in the Ag matrix. However, dipolar interactions are not affected by the annealing. On the contrary, at x = 35, around the magnetic percolation, the annealing gives rise to an increasingly ordered interface, thereby enhancing the transfer of the direct exchange interactions.

  5. 导电导磁层状介质上的固定翼航空瞬变电磁响应%The Fixed-wing Airborne Transient Electromagnetic response of a magnetic conductive layered medium

    Institute of Scientific and Technical Information of China (English)

    覃庆炎; 王绪本; 毛立峰

    2011-01-01

    Based on the electromagnetic theory, the forward formulae is obtained for Fixed-wing Airborne Transient Electromagnetic(ATEM) method in a magnetic conductive layered earth which contains dielectric parameters, conductivity and permeability parameters. The computer program for computing the ATEM response is worked out and the forward computing is completed for the theoretical models. According to the results of forward computing, we analyzed how the dielectric constant, resistivity, susceptibility and flight height influence the electromagnetic response. The results show that (1) Under the same condition, the lower the resistivity of the layered earth the greater the early time airborne electromagnetic response; (2) The dielectric parameters affect only the early time electromagnetic response and can be ignored at the late time; (3) The larger the permeability the greater the airborne electromagnetic response, so for the high permeability media, we can not ignore the influence of magnetic; (4) The higher the flight, the weaker the airborne electromagnetic response; The change in flight height will caused the distortion of airborne electromagnetic response, the lower flight height will cause the larger distortion than the higher flight height; For the good conductivity medium or the good permeability medium, the change in flight height will cause the larger relative error in the received signal.%基于电磁理论,导出了含介电参数、电导率参数和磁导率参数的导电导磁层状大地条件下的固定翼航空瞬变电磁响应的计算公式.编制了计算机程序,并对理论模型进行正演计算,根据计算结果分析了模型的介电常数、电阻率和磁导率参数、飞行高度参数对响应的影响.理论模型的计算结果显示当其它条件相同时,介质电阻率越小或磁导率越大,则航空电磁响应也越大;而介质的介电参数变化仅影响早期的电磁响应,晚期的响应可以忽略介电因素的

  6. Analysis and reduction of thermal magnetic noise in liquid-He dewar for sensitive low-field nuclear magnetic resonance measurements

    International Nuclear Information System (INIS)

    For sensitive measurements of micro-Tesla nuclear magnetic resonance (μT-NMR) signal, a low-noise superconducting quantum interference device (SQUID) system is needed. We have fabricated a liquid He dewar for an SQUID having a large diameter for the pickup coil. The initial test of the SQUID system showed much higher low-frequency magnetic noise caused by the thermal magnetic noise of the aluminum plates used for the vapor-cooled thermal shield material. The frequency dependence of the noise spectrum showed that the noise increases with the decrease of frequency. This behavior could be explained from a two-layer model; one generating the thermal noise and the other one shielding the thermal noise by eddy-current shielding. And the eddy-current shielding effect is strongly dependent on the frequency through the skin-depth. To minimize the loop size for the fluctuating thermal noise current, we changed the thermal shield material into insulated thin Cu mesh. The magnetic noise of the SQUID system became flat down to 0.1 Hz with a white noise of 0.3 fT√Hz, including the other noise contributions such as SQUID electronics and magnetically shielded room, etc, which is acceptable for low-noise μT-NMR experiments.

  7. Tidal Heating of Earth-like Exoplanets around M Stars: Thermal, Magnetic, and Orbital Evolutions.

    Science.gov (United States)

    Driscoll, P E; Barnes, R

    2015-09-01

    The internal thermal and magnetic evolution of rocky exoplanets is critical to their habitability. We focus on the thermal-orbital evolution of Earth-mass planets around low-mass M stars whose radiative habitable zone overlaps with the "tidal zone," where tidal dissipation is expected to be a significant heat source in the interior. We develop a thermal-orbital evolution model calibrated to Earth that couples tidal dissipation, with a temperature-dependent Maxwell rheology, to orbital circularization and migration. We illustrate thermal-orbital steady states where surface heat flow is balanced by tidal dissipation and cooling can be stalled for billions of years until circularization occurs. Orbital energy dissipated as tidal heat in the interior drives both inward migration and circularization, with a circularization time that is inversely proportional to the dissipation rate. We identify a peak in the internal dissipation rate as the mantle passes through a viscoelastic state at mantle temperatures near 1800 K. Planets orbiting a 0.1 solar-mass star within 0.07 AU circularize before 10 Gyr, independent of initial eccentricity. Once circular, these planets cool monotonically and maintain dynamos similar to that of Earth. Planets forced into eccentric orbits can experience a super-cooling of the core and rapid core solidification, inhibiting dynamo action for planets in the habitable zone. We find that tidal heating is insignificant in the habitable zone around 0.45 (or larger) solar-mass stars because tidal dissipation is a stronger function of orbital distance than stellar mass, and the habitable zone is farther from larger stars. Suppression of the planetary magnetic field exposes the atmosphere to stellar wind erosion and the surface to harmful radiation. In addition to weak magnetic fields, massive melt eruption rates and prolonged magma oceans may render eccentric planets in the habitable zone of low-mass stars inhospitable for life. PMID:26393398

  8. Magnetic Thermal Ablation Using Ferrofluids: Influence of Administration Mode on Biological Effect in Different Porcine Tissues

    International Nuclear Information System (INIS)

    The purpose of this study was to compare the effects of magnetic thermal ablation in different porcine tissues using either a singular injection or a continuous infusion of superparamagnetic iron oxide nanoparticles. In the first setting samples of three ferrofluids containing different amounts of iron (1:171, 2:192, and 3:214 mg/ml) were singularly interstitially injected into specimens of porcine liver, kidney, and muscle (n = 5). Then the specimens were exposed to an alternating magnetic field (2.86 kA/m, 190 kHz) generated by a circular coil for 5 min. In the second experimental setup ferrofluid samples were continuously interstitially infused into the tissue specimens during the exposure to the magnetic field. To measure the temperature increase two fiber-optic temperature probes with a fixed distance of 0.5 cm were inserted into the specimens along the puncture tract of the injection needle and the temperature was measured every 15 s. Finally, the specimens were dissected, the diameters of the created thermal lesions were measured, and the volumes were calculated and compared. Compared to continuous infusion, a single injection of ferrofluids resulted in smaller coagulation volumes in all tissues. Significant differences regarding coagulation volume were found in kidney and muscle specimens. The continuous infusion technique led to more elliptically shaped coagulation volumes due to larger diameters along the puncture tract. Our data show the feasibility of magnetic thermal ablation using either a single interstitial injection or continuous infusion for therapy of lesions in muscle, kidney, and liver. Continuous infusion of ferrofluids results in larger zones of necrosis compared to a single injection technique.

  9. Airborne EM applied to environmental geoscience in the UK

    OpenAIRE

    Beamish, D

    2002-01-01

    The British Geological Survey (BGS) has been highlighting the need for modern, multi-sensor airborne geophysical data in the UK. Here David Beamish, geophysicist with the BGS, describes the first trial airborne electromagnetic data acquired and its relevance to environmental geoscience. The lack of modern, multi-sensor (magnetic, radiometric and electromagnetic) data represents one of the most serious gaps in the geoscience knowledge base of the UK, and a national, high resolution airborne su...

  10. Tidal Heating of Earth-like Exoplanets around M Stars: Thermal, Magnetic, and Orbital Evolutions

    Science.gov (United States)

    Barnes, R.

    2015-01-01

    Abstract The internal thermal and magnetic evolution of rocky exoplanets is critical to their habitability. We focus on the thermal-orbital evolution of Earth-mass planets around low-mass M stars whose radiative habitable zone overlaps with the “tidal zone,” where tidal dissipation is expected to be a significant heat source in the interior. We develop a thermal-orbital evolution model calibrated to Earth that couples tidal dissipation, with a temperature-dependent Maxwell rheology, to orbital circularization and migration. We illustrate thermal-orbital steady states where surface heat flow is balanced by tidal dissipation and cooling can be stalled for billions of years until circularization occurs. Orbital energy dissipated as tidal heat in the interior drives both inward migration and circularization, with a circularization time that is inversely proportional to the dissipation rate. We identify a peak in the internal dissipation rate as the mantle passes through a viscoelastic state at mantle temperatures near 1800 K. Planets orbiting a 0.1 solar-mass star within 0.07 AU circularize before 10 Gyr, independent of initial eccentricity. Once circular, these planets cool monotonically and maintain dynamos similar to that of Earth. Planets forced into eccentric orbits can experience a super-cooling of the core and rapid core solidification, inhibiting dynamo action for planets in the habitable zone. We find that tidal heating is insignificant in the habitable zone around 0.45 (or larger) solar-mass stars because tidal dissipation is a stronger function of orbital distance than stellar mass, and the habitable zone is farther from larger stars. Suppression of the planetary magnetic field exposes the atmosphere to stellar wind erosion and the surface to harmful radiation. In addition to weak magnetic fields, massive melt eruption rates and prolonged magma oceans may render eccentric planets in the habitable zone of low-mass stars inhospitable for life. Key Words

  11. Mn-Zn ferrite nanoparticles for ferrofluid preparation: Study on thermal-magnetic properties

    International Nuclear Information System (INIS)

    Mn1-xZnxFe2O4 (with x varying from 0.1 to 0.5) ferrite nanoparticles used for ferrofluid preparation have been prepared by chemical co-precipitation method and characterized. Characterization techniques like elemental analysis by atomic absorption spectroscopy and spectrophotometry, thermal analysis using simultaneous TG-DTA, XRD, TEM, VSM and Moessbauer spectroscopy have been utilized. The final cation contents estimated agree with the initial degree of substitution. The Curie temperature (Tc) and particle size decrease with the increase in zinc substitution. In the case of particles with higher zinc concentration, both ferrimagnetic nanoparticles and particles exhibiting superparamagnetic behavior at room temperature are present. In addition, some of the results obtained by slightly altering the preparation condition are also discussed. The precipitated particles were used for ferrofluid preparation. The fine particles were suitably dispersed in heptane using oleic acid as the surfactant. The volatile nature of the carrier chosen helps in altering the number concentration of the magnetic particles in a ferrofluid. Magnetic properties of the fine particles and ferrofluids are discussed. Ferrofluids having Mn0.5Zn0.5Fe2O4 particles can be used for the energy conversion application utilizing the magnetically induced convection for thermal dissipation

  12. Effect of magnetized phonons on electrical and thermal conductivity of neutron star crust

    CERN Document Server

    Baiko, D A

    2016-01-01

    We study electrical and thermal conductivities of degenerate electrons emitting and absorbing phonons in a strongly magnetized crystalline neutron star crust. We take into account modification of the phonon spectrum of a Coulomb solid of ions caused by a strong magnetic field. Boltzmann transport equation is solved using a generalized variational method. The ensuing three-dimensional integrals over the transferred momenta are evaluated by two different numerical techniques, the Monte-Carlo method and a regular integration over the first Brillouin zone. The results of the two numerical approaches are shown to be in a good agreement. An appreciable growth of electrical and thermal resistivities is reported at quantum and intermediate temperatures $T \\lesssim 0.1 T_{\\rm p}$ ($T_{\\rm p}$ is the ion plasma temperature) in a wide range of chemical compositions and mass densities of matter even for moderately magnetized crystals $\\omega_{\\rm B} \\sim \\omega_{\\rm p}$ ($\\omega_{\\rm B}$ and $\\omega_{\\rm p}$ are the ion ...

  13. Airborne geoid determination

    DEFF Research Database (Denmark)

    Forsberg, René; Olesen, Arne Vestergaard; Bastos, L.; Gidskehaug, A.; Meyer, U.; Timmen, L.

    2000-01-01

    Airborne geoid mapping techniques may provide the opportunity to improve the geoid over vast areas of the Earth, such as polar areas, tropical jungles and mountainous areas, and provide an accurate "seam-less" geoid model across most coastal regions. Determination of the geoid by airborne methods...... relies on the development of airborne gravimetry, which in turn is dependent on developments in kinematic GPS. Routine accuracy of airborne gravimetry are now at the 2 mGal level, which may translate into 5-10 cm geoid accuracy on regional scales. The error behaviour of airborne gravimetry is well...

  14. Design of an axial flux PM motor using magnetic and thermal equivalent network

    Science.gov (United States)

    Mignot, Romain-Bernard; Glises, Raynal; Espanet, Christophe; Saint Ellier, Emeline; Dubas, Frédéric; Chamagne, Didier

    2013-09-01

    This paper deals with the development of a new generation of electric motors (7.5-15 kW) for automotive powertrains. The target is a full electric direct drive vehicle, for the particular application to heavy quadricycles. An original axial flux PM structure is proposed due to the simplicity of its manufacturing. However it leads to a 3D structure, difficult to study. The paper deals with analytical models that can be used to achieve the analysis and the sizing of the motor. The electromagnetic behavior is modeled using a simple magnetic equivalent network and the thermal behavior is analyzed with a thermal network. Finally, the analytical results are compared to those experimentally obtained and it proves the interest of the proposed structure: the construction is simple and the performances are satisfying.

  15. Clinical utility of magnetic resonance thermal imaging (MRTI) for realtime guidance of deep hyperthermia

    Science.gov (United States)

    Stauffer, P. R.; Craciunescu, Oana I.; Maccarini, P. F.; Wyatt, Cory; Arunachalam, K.; Arabe, O.; Stakhursky, V.; Soher, B.; MacFall, J. R.; Li, Z.; Joines, William T.; Rangarao, S.; Cheng, K. S.; Das, S. K.; Martins, Carlos D.; Charles, Cecil; Dewhirst, Mark W.; Wong, T.; Jones, E.; Vujaskovic, Z.

    2009-02-01

    A critical need has emerged for volumetric thermometry to visualize 3D temperature distributions in real time during deep hyperthermia treatments used as an adjuvant to radiation or chemotherapy for cancer. For the current effort, magnetic resonance thermal imaging (MRTI) is used to measure 2D temperature rise distributions in four cross sections of large extremity soft tissue sarcomas during hyperthermia treatments. Novel hardware and software techniques are described which improve the signal to noise ratio of MR images, minimize motion artifact from circulating coupling fluids, and provide accurate high resolution volumetric thermal dosimetry. For the first 10 extremity sarcoma patients, the mean difference between MRTI region of interest and adjacent interstitial point measurements during the period of steady state temperature was 0.85°C. With 1min temporal resolution of measurements in four image planes, this noninvasive MRTI approach has demonstrated its utility for accurate monitoring and realtime steering of heat into tumors at depth in the body.

  16. Load frequency stabilization of four area hydro thermal system using Superconducting Magnetic Energy Storage system

    Directory of Open Access Journals (Sweden)

    A.Ruby meena

    2014-07-01

    Full Text Available Automatic generation control in electric power system design is a major concern nowadays due to its rising size, varying structure, integration of renewable-energy sources and distributed generators to meet the growing demand. In this paper, automatic generation control of an interconnected four area hydro thermal system examined. Each area equipped with reheat turbine for thermal system and hydro turbine with electric governor for hydro system. Load frequency stabilization gained by including Superconducting Magnetic Energy Storage system (SMES in all areas. A comparative analysis made between Proportional and Integral (PI controller with Fuzzy Logic controller with and without including SMES in the four area power system. The designed Fuzzy Logic Controller can generate best dynamic performance for step load perturbations given in all areas. The system simulation realized by using MATLAB software.

  17. On the quantum magnetic oscillations of electrical and thermal conductivities of graphene

    Science.gov (United States)

    Alisultanov, Z. Z.; Reis, M. S.

    2016-05-01

    Oscillating thermodynamic quantities of diamagnetic materials, specially graphene, have been attracting attention of the scientific community due to the possibility to experimentally map the Fermi surface of the material. These have been the case of the de Haas-van Alphen and Shubnikov-de Haas effects, found on the magnetization and electrical conductivity, respectively. In this direction, managing the thermodynamic oscillations is of practical purpose, since from the reconstructed Fermi surface it is possible to access, for instance, the electronic density. The present work theoretically explores the quantum oscillations of electrical and thermal conductivities of a monolayer graphene under a crossed magnetic and electric fields. We found that the longitudinal electric field can increase the amplitude of the oscillations and this result is of practical and broad interest for both, experimental and device physics.

  18. Deterministic drift instability and stochastic thermal perturbations of magnetic dissipative droplet solitons

    Science.gov (United States)

    Wills, P.; Iacocca, E.; Hoefer, M. A.

    2016-04-01

    The magnetic dissipative droplet is a strongly nonlinear wave structure that can be stabilized in a thin film ferromagnet exhibiting perpendicular magnetic anisotropy by use of spin transfer torque. These structures have been observed experimentally at room temperature, showcasing their robustness against noise. Here, we quantify the effects of thermal noise by deriving stochastic equations of motion for a droplet based on soliton perturbation theory. First, it is found that deterministic droplets are linearly unstable at large bias currents, subject to a drift instability. When the droplet is linearly stable, our framework allows us to analytically compute the droplet's generation linewidth and center variance. Additionally, we study the influence of nonlocal and Oersted fields with micromagnetic simulations, providing insight into their effect on the generation linewidth. These results motivate detailed experiments on the current and temperature-dependent linewidth as well as drift instability statistics of droplets, which are important figures-of-merit in the prospect of droplet-based applications.

  19. Transient Thermal Analysis of Intense Proton Beam Loss on a Kicker Magnet Conductor Plate

    CERN Document Server

    Knaus, P

    2000-01-01

    The Super Proton Synchrotron SPS will be used as injector for the Large Hadron Collider LHC and needs adaptation to meet LHC requirements. The SPS injection kicker magnets MKP will undergo important modifications to comply with the requirements on magnetic field rise-time and ripple. The injection kicker presently installed has a return conductor of beryllium to minimise the risk of metal evaporation from its surface due to heating caused by beam impact. In the context of refurbishing the MKP to satisfy LHC requirements these conductors need replacement, preferably with a less delicate material. This article presents the transient thermal analysis of energy deposition caused by beam loss on the conductor plate. The expected time structure of the beam is taken into account. Simulations comparing different conductor materials have been performed, leading to the result that a significantly cheaper and fully inoffensive titanium alloy can satisfy the needs.

  20. Tridimensional Burning Structures Associated with Anisotropic Thermal Conductivities in Magnetically Confined and Pulsar Plasmas

    Science.gov (United States)

    Cardinali, A.; Coppi, B.; Sonnino, G.

    2015-11-01

    A surprising result of the most recent theory of the thermonuclear instability, which can take place in D-T plasmas close to ignition, is that it can develop with tridimensional structures emerging from an axisymmetric toroidal confinement configurations. These structures are helical filaments (``snakes'') that are localized radially around a given rational magnetic surface. Until now well known analyses of fusion burning processes in magnetically confined plasmas, that include the thermonuclear instability, have been carried out by 1+1/2 D transport codes and, consequently, the onset of tri-dimensional structures has not been investigated. The importance of the electron thermal conductivities anisotropy is pointed out also for the inhomogeneous thermonuclear burning of plasmas on the surface of pulsars and for the formation of the observed bright spots on some of them. Sponsored in part by the U.S. DoE.

  1. Electrical, thermal, catalytic and magnetic properties of nano-structured materials and their applications

    Science.gov (United States)

    Liu, Zuwei

    Nanotechnology is a subject that studies the fabrication, properties, and applications of materials on the nanometer-scale. Top-down and bottom-up approaches are commonly used in nano-structure fabrication. The top-down approach is used to fabricate nano-structures from bulk materials by lithography, etching, and polishing etc. It is commonly used in mechanical, electronic, and photonic devices. Bottom-up approaches fabricate nano-structures from atoms or molecules by chemical synthesis, self-assembly, and deposition, such as sol-gel processing, molecular beam epitaxy (MBE), focused ion beam (FIB) milling/deposition, chemical vapor deposition (CVD), and electro-deposition etc. Nano-structures can have several different dimensionalities, including zero-dimensional nano-structures, such as fullerenes, nano-particles, quantum dots, nano-sized clusters; one-dimensional nano-structures, such as carbon nanotubes, metallic and semiconducting nanowires; two-dimensional nano-structures, such as graphene, super lattice, thin films; and three-dimensional nano-structures, such as photonic structures, anodic aluminum oxide, and molecular sieves. These nano-structured materials exhibit unique electrical, thermal, optical, mechanical, chemical, and magnetic properties in the quantum mechanical regime. Various techniques can be used to study these properties, such as scanning probe microscopy (SPM), scanning/transmission electron microscopy (SEM/TEM), micro Raman spectroscopy, etc. These unique properties have important applications in modern technologies, such as random access memories, display, solar energy conversion, chemical sensing, and bio-medical devices. This thesis includes four main topics in the broad area of nanoscience: magnetic properties of ferro-magnetic cobalt nanowires, plasmonic properties of metallic nano-particles, photocatalytic properties of titanium dioxide nanotubes, and electro-thermal-optical properties of carbon nanotubes. These materials and their

  2. Electrochemical properties of a thermally expanded magnetic graphene composite with a conductive polymer.

    Science.gov (United States)

    Ahmed, Mahmoud M M; Imae, Toyoko

    2016-04-21

    A magnetic graphene composite derived from stage-1 FeCl3-graphite intercalation compounds was thermally treated for up to 75 min at 400 °C or for 2 min at high temperatures up to 900 °C. These heat-treatments of the magnetic graphene composite gave rise to the cubical expansion of graphene with the enlargement of inter-graphene distances. The specific capacitance of the magnetic graphene composite increased upon heating and reached 42 F g(-1) at a scan rate of 5 mV s(-1) in 1.0 M NaCl, after being treated for 2 min at 900 °C. This value corresponds to 840% increase in the capacitance activity superior to that (5 F g(-1)) of the pristine magnetic graphene composite before heat-treatment. This capacitance enhancement can play a significant role in the increase of the surface area that reached 17.2 m(2) g(-1) during the non-defective inter-graphene exfoliation. Moreover, the magnetic graphene composite heated at 900 °C was hybridized with polyaniline by in situ polymerization of aniline to reach a specific capacitance of 253 F g(-1) at 5 mV s(-1). The current procedure of heat-treatment and hybridization with a conductive polymer can be an effective method for attaining a well-expanded magnetic graphene composite possessing an enhanced electrochemical activity with a relatively high energy density (141 W h kg(-1) in 1.0 M NaCl) and an excellent stability (99% after 9000 cycles of 20 A g(-1)). PMID:27030519

  3. Magnetism and thermal induced characteristics of Fe{sub 2}O{sub 3} content bioceramics

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Chun-Shiang; Hsi, Chi-Shiung [Department of Materials Science and Engineering, National United University, Miaoli 36003, Taiwan (China); Hsu, Fang-Chi, E-mail: fangchi@nuu.edu.tw [Department of Materials Science and Engineering, National United University, Miaoli 36003, Taiwan (China); Wang, Moo-Chin [Department of Fragrance and Cosmetics, Kaohsiung Medical University, Kaohsiung 807, Taiwan (China); Chen, Yung-Sheng [Department of Materials Science and Engineering, I-Shou University, Kaohsiung 803, Taiwan (China)

    2012-11-15

    Magnetic properties of Li{sub 2}O-MnO{sub 2}-CaO-P{sub 2}O{sub 5}-SiO{sub 2} (LMCPS) glasses doped with various amounts of Fe{sub 2}O{sub 3} were investigated. There is a dramatic change in the magnetic property of pristine LMCPS after the addition of Fe{sub 2}O{sub 3} and crystallized at 850 Degree-Sign C for 4 h. Both the electron paramagnetic resonance and magnetic susceptibility measurements showed that the glass ceramic with 4 at% Fe{sub 2}O{sub 3} exhibited the coexistence of superparamagnetism and ferromagnetism at room temperature. When the Fe{sub 2}O{sub 3} content was higher than 8 at%, the LMCPS glasses showed ferromagnetism behavior. The complex magnetic behavior is due to the distribution of (Li, Mn)ferrite particle sizes driven by the Fe{sub 2}O{sub 3} content. The thermal induced hysteresis loss of the crystallized LMCPS glass ceramics was characterized under an alternating magnetic field. The energy dissipations of the crystallized LMCPS glass ceramics were determined by the concentration and Mn/Fe ratios of Li(Mn, Fe)ferrite phase formed in the glass ceramics. - Highlights: Black-Right-Pointing-Pointer Presence of Fe{sub 2}O{sub 3} in LMCPS glass ceramic promotes the growth of (Li, Mn)ferrite. Black-Right-Pointing-Pointer The amount of Fe{sub 2}O{sub 3} determines the size of (Li,Mn)ferrite particles. Black-Right-Pointing-Pointer Room temperature superparamagnetism was obtained at 4 at% of Fe{sub 2}O{sub 3} addition. Black-Right-Pointing-Pointer In addition, Li(Mn, Fe)ferrite phase contributes to the magnetic energy loss. Black-Right-Pointing-Pointer The largest energy loss is the trade-off between the ferrite content and Mn/Fe ratio.

  4. Magnetism and thermal induced characteristics of Fe2O3 content bioceramics

    International Nuclear Information System (INIS)

    Magnetic properties of Li2O–MnO2–CaO–P2O5–SiO2 (LMCPS) glasses doped with various amounts of Fe2O3 were investigated. There is a dramatic change in the magnetic property of pristine LMCPS after the addition of Fe2O3 and crystallized at 850 °C for 4 h. Both the electron paramagnetic resonance and magnetic susceptibility measurements showed that the glass ceramic with 4 at% Fe2O3 exhibited the coexistence of superparamagnetism and ferromagnetism at room temperature. When the Fe2O3 content was higher than 8 at%, the LMCPS glasses showed ferromagnetism behavior. The complex magnetic behavior is due to the distribution of (Li, Mn)ferrite particle sizes driven by the Fe2O3 content. The thermal induced hysteresis loss of the crystallized LMCPS glass ceramics was characterized under an alternating magnetic field. The energy dissipations of the crystallized LMCPS glass ceramics were determined by the concentration and Mn/Fe ratios of Li(Mn, Fe)ferrite phase formed in the glass ceramics. - Highlights: ► Presence of Fe2O3 in LMCPS glass ceramic promotes the growth of (Li, Mn)ferrite. ► The amount of Fe2O3 determines the size of (Li,Mn)ferrite particles. ► Room temperature superparamagnetism was obtained at 4 at% of Fe2O3 addition. ► In addition, Li(Mn, Fe)ferrite phase contributes to the magnetic energy loss. ► The largest energy loss is the trade-off between the ferrite content and Mn/Fe ratio.

  5. Tidal heating of Earth-like exoplanets around M stars: Thermal, magnetic, and orbital evolutions

    CERN Document Server

    Driscoll, Peter

    2015-01-01

    The internal thermal and magnetic evolution of rocky exoplanets is critical to their habitability. We focus on the thermal-orbital evolution of Earth-mass planets around low mass M stars whose radiative habitable zone overlaps with the "tidal zone". We develop a thermal-orbital evolution model calibrated to Earth that couples tidal dissipation, with a temperature-dependent Maxwell rheology, to orbital circularization and migration. We illustrate thermal-orbital steady states where surface heat flow is balanced by tidal dissipation and cooling can be stalled for billions of years until circularization occurs. Orbital energy dissipated as tidal heat in the interior drives both inward migration and circularization, with a circularization time that is inversely proportional to the dissipation rate. We identify a peak in the internal dissipation rate as the mantle passes through a visco-elastic state at mantle temperatures near 1800 K. Planets orbiting a 0.1 solar-mass star within $0.07$ AU circularize before 10 G...

  6. Computational Dynamics of Arterial Blood Flow in the Presence of Magnetic Field and Thermal Radiation Therapy

    Directory of Open Access Journals (Sweden)

    T. Chinyoka

    2014-01-01

    Full Text Available We conduct a numerical study to determine the influence of magnetic field and thermal radiation on both velocity and temperature distributions in a single blood vessel. The model here assumes that blood is a Newtonian incompressible conducting fluid with radially varying viscosity due to hematocrit variation. The transient equations of momentum and energy transport governing the flow in an axisymmetric configuration are solved numerically using a semi-implicit finite difference method. Results are presented graphically and discussed both qualitatively and quantitatively from the physiological point of view. The results of this work may enhance current understanding of the factors that determine the effects of hyperthermia treatment on tumor tissues.

  7. Magnetic and Thermal Analysis of Current Transformer in Normal and Abnormal Conditions

    OpenAIRE

    M. B.B. Sharifian; M. Farrokhifar; R. Esmaeilzadeh; K. B. Ali-Abasi; A. Ghahramani; E Amini

    2008-01-01

    Calculation of Current Transformers (CTs) magnetic and thermal properties are very complex due to the complexity of their construction, different properties of their materials and non-linearity of core B-H curve. Finite Element Methods (FEMs) are very capable and reliable methods for these problems solution, such as Ansys software. In this study Ansys software is applied in analysis of an 800-400/5-5 CT. These analyses consist of 2D static normal, open circuit and short circuit condition of C...

  8. A diagram for the representation of thermal, mechanical, and magnetic interaction in diamagnetic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kloos, Gerhard [Technical Bureau for Optics and Electromechanics, Fellbach (Germany)

    1999-12-07

    A diagram is derived that visualizes the interplay of macroscopic thermal, mechanical, and magnetic effects in a diamagnetic crystal. The derivation is based on a Taylor expansion of a thermodynamic potential and on a theorem on the transformation behaviour of property tensors under time inversion. The interaction diagram provides a quick answer to the experimenter on the question of which linear and quadratic physical effects are possible in the given physical situation and how the measurement of an effect under study might be influenced by cross-effects. (author)

  9. Fabrication of nanoceramic hin-wall tubes by magnetic pulsed compaction and thermal sintering

    Directory of Open Access Journals (Sweden)

    Ivanov V.V.

    2005-01-01

    Full Text Available Gasproof thin-wall tubes of fine-grained ceramics based on zirconia and gadolinia have been produced by magnetic pulsed compaction and thermal sintering. Data on their structures and electric characteristics are presented. The tubes with a diameter of ~ 15 mm, wall thickness of ~ 0.7 mm, and length up to 80 mm are characterized by an uniform porous-free structure with a mean grain size in the range of 100 - 300 nm. The obtained ceramics possess high electrolytic properties.

  10. Channeled PIXE and magnetic measurements in Co implanted and thermally annealed ZnO single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Werner, Z., E-mail: wernerz@ipj.gov.pl [National Centre for Nuclear Research, 7 Sołtana Street, 05-400 Otwock (Poland); Ratajczak, R. [National Centre for Nuclear Research, 7 Sołtana Street, 05-400 Otwock (Poland); Gosk, J. [Institute of Experimental Physics, University of Warsaw, 69 Hoża Street, 00-681 Warsaw (Poland); Faculty of Physics, Warsaw University of Technology, 75 Koszykowa Street, 00-662 Warsaw (Poland); Barlak, M. [National Centre for Nuclear Research, 7 Sołtana Street, 05-400 Otwock (Poland); Twardowski, A. [Institute of Experimental Physics, University of Warsaw, 69 Hoża Street, 00-681 Warsaw (Poland); Pochrybniak, C. [National Centre for Nuclear Research, 7 Sołtana Street, 05-400 Otwock (Poland); Zhao, Q. [KU Leuven, Nuclear and Radiation Physics Section, Celestijnenlaan 200d – box 2418, Leuven (Belgium)

    2014-08-15

    Highlights: • Exceptionally high magnetic moment has been found in ZnO single crystals implanted with 120 keV Co ions to a fluence of 0.6 × 10{sup 16} cm{sup −2} and 1.2 × 10{sup 16} cm{sup −2}. • Paramagnetic and ferromagnetic phases present after implantation transform into a paramagnetic phase following 800 °C annealing. • The magnetism is attributed to implantation-induced defects. - Abstract: Single crystals of ZnO were implanted with 0.6 × 10{sup 16} cm{sup −2} and 1.2 × 10{sup 16} cm{sup −2} of Co ions produced by MEVVA type implanter. Channeled Rutherford backscattering (cRBS) measurements reveal incomplete amorphisation. Thermal annealing at 800 °C in argon leads to a reduction of point-type defects. The channeled particle-induced X-ray emission (cPIXE) measurements show partial substitutionality of Co ions directly following implantation with further growth of substitutional occupation after annealing. Magnetic measurements reveal the presence of paramagnetic and ferromagnetic phases after implantation. The value of magnetization can be interpreted as due to defects rather than Co content. The ferromagnetic phase disappears after annealing and the paramagnetic phase grows in intensity.

  11. Preparation and magnetic properties of nickel nanorods by thermal decomposition reducing methods

    Institute of Scientific and Technical Information of China (English)

    LUO Yu; ZHANG Jian-cheng; SHEN Yue; JIANG Shu-tao; LIU Guo-yong; WANG Lin-jun

    2006-01-01

    The single-crystalline nickel nanorods with narrow size distribution and better magnetic properties were synthesized by thermal decomposition of nickel hydroxide nanorods precursor powders,which were produced by soft template method using nickel oxalic acid as raw material. The influences of hydrothermal reaction temperature and time on morphology of the products were investigated. The structure,morphology and magnetic properties of the products were characterized by X-ray powder diffraction (XRD),transmission electron microscopy (TEM),thermogravimetric differential scanning calorimetry (TGA-DSC) and vibrating sample magnetometer (VSM). The as-prepared nickel nanorods are uniform with a diameter of 10-15 nm and length 70-120 nm. The results of magnetic measurements show that the specific saturation magnetization(ós) and coercivity values(Hc) of the nickel nanorods are 50.649 A·m2/kg and 190.0×(103/4π)A/m,respectively. Finally,a possible mechanism for the formation of nickel nanorods was discussed briefly.

  12. Observations of thermally excited ferromagnetic resonance on spin torque oscillators having a perpendicularly magnetized free layer

    Energy Technology Data Exchange (ETDEWEB)

    Tamaru, S., E-mail: shingo.tamaru@aist.go.jp; Kubota, H.; Yakushiji, K.; Konoto, M.; Nozaki, T.; Fukushima, A.; Imamura, H.; Taniguchi, T.; Arai, H.; Tsunegi, S.; Yuasa, S. [Spintronics Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); Suzuki, Y. [Spintronics Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan)

    2014-05-07

    Measurements of thermally excited ferromagnetic resonance were performed on spin torque oscillators having a perpendicularly magnetized free layer and in-plane magnetized reference layer (abbreviated as PMF-STO in the following) for the purpose of obtaining magnetic properties in the PMF-STO structure. The measured spectra clearly showed a large main peak and multiple smaller peaks on the high frequency side. A Lorentzian fit on the main peak yielded Gilbert damping factor of 0.0041. The observed peaks moved in proportion to the out-of-plane bias field. From the slope of the main peak frequency as a function of the bias field, Lande g factor was estimated to be about 2.13. The mode intervals showed a clear dependence on the diameter of the PMF-STOs, i.e., intervals are larger for a smaller diameter. These results suggest that the observed peaks should correspond to eigenmodes of lateral spin wave resonance in the perpendicularly magnetized free layer.

  13. Engineered Theranostic Magnetic Nanostructures: Role of Composition and Surface Coating on Magnetic Resonance Imaging Contrast and Thermal Activation.

    Science.gov (United States)

    Nandwana, Vikas; Ryoo, Soo-Ryoon; Kanthala, Shanthi; De, Mrinmoy; Chou, Stanley S; Prasad, Pottumarthi V; Dravid, Vinayak P

    2016-03-23

    Magnetic nanostructures (MNS) have emerged as promising functional probes for simultaneous diagnostics and therapeutics (theranostic) applications due to their ability to enhance localized contrast in magnetic resonance imaging (MRI) and heat under external radio frequency (RF) field, respectively. We show that the "theranostic" potential of the MNS can be significantly enhanced by tuning their core composition and architecture of surface coating. Metal ferrite (e.g., MFe2O4) nanoparticles of ∼8 nm size and nitrodopamine conjugated polyethylene glycol (NDOPA-PEG) were used as the core and surface coating of the MNS, respectively. The composition was controlled by tuning the stoichiometry of MFe2O4 nanoparticles (M = Fe, Mn, Zn, ZnxMn1-x) while the architecture of surface coating was tuned by changing the molecular weight of PEG, such that larger weight is expected to result in longer length extended away from the MNS surface. Our results suggest that both core as well as surface coating are important factors to take into consideration during the design of MNS as theranostic agents which is illustrated by relaxivity and thermal activation plots of MNS with different core composition and surface coating thickness. After optimization of these parameters, the r2 relaxivity and specific absorption rate (SAR) up to 552 mM(-1) s(-1) and 385 W/g were obtained, respectively, which are among the highest values reported for MNS with core magnetic nanoparticles of size below 10 nm. In addition, NDOPA-PEG coated MFe2O4 nanostructures showed enhanced biocompatibility (up to [Fe] = 200 μg/mL) and reduced nonspecific uptake in macrophage cells in comparison to other well established FDA approved Fe based MR contrast agents. PMID:26936392

  14. Application of differential thermal analysis to investigation of magnetic field effect on solidification of Al-Cu hypereutectic alloy

    Energy Technology Data Exchange (ETDEWEB)

    Li Chuanjun; Yang Hui [School of Materials Science and Engineering and Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China); Ren Zhongming, E-mail: zmren@staff.shu.edu.c [School of Materials Science and Engineering and Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China); Ren Weili; Wu Yuqin [School of Materials Science and Engineering and Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China)

    2010-08-27

    Investigation of solidification in the Al-25 at.%Cu hypereutectic alloy in magnetic fields has been carried out by differential thermal analysis (DTA). The DTA results indicated that the nucleation temperatures of primary Al{sub 2}Cu phases and Al-Al{sub 2}Cu eutectics were lowered and the rates of crystal growth including primary phases and eutectics were reduced although the melting of the alloy was almost not affected in magnetic fields of 6 T and 12 T in comparison with those without a magnetic field. The suppression of nucleation and growth of primary phases and eutectics might be mainly attributed to reduction of diffusion rates of atoms in a magnetic field on the condition of suppression of convections. Primary Al{sub 2}Cu phases oriented along a magnetic field compared with disorder ones without a magnetic field, which was caused by the magnetic anisotropy.

  15. Coupled granular/continuous medium for thermally stable perpendicular magnetic recording

    Science.gov (United States)

    Sonobe, Y.; Weller, D.; Ikeda, Y.; Takano, K.; Schabes, M. E.; Zeltzer, G.; Do, H.; Yen, B. K.; Best, M. E.

    2001-10-01

    We studied coupled granular/continuous (CGC) perpendicular media consisting of a continuous multilayer structure and a granular layer. The addition of Co/Pt multilayers decreased the nucleation field from 200 to -1800 Oe and increased the squareness from 0.9 to 1.0. The moment decay at room temperature was significantly reduced from -4.8% to -0.05% per decade. At elevated temperatures, strong exchange coupling between a granular layer and a continuous layer is needed for thermal stability. The exchange-coupled continuous layer reduces thermal demagnetization as it effectively increases the grain size, tightens the grain distribution, and prevents the reversal of individual grains. Magnetic Force Microscope image showed a larger magnetic cluster size for the CGC structure. Compared to the CoCr 18Pt 12 medium, the CGC medium had 2.3 dB higher output. However, the noise for the CGC medium increased with the recording density, while the noise for the CoCr 18Pt 12 medium remained constant from 4 to 15 kfc/mm. Further optimization and noise reduction are still required for future high density recording.

  16. Thermal evolution and lifetime of intrinsic magnetic fields of Super Earths in habitable zones

    CERN Document Server

    Tachinami, Chihiro; Ida, Shigeru

    2010-01-01

    We have numerically studied the thermal evolution of various-mass terrestrial planets in habitable zones, focusing on duration of dynamo activity to generate their intrinsic magnetic fields, which may be one of key factors in habitability on the planets. In particular, we are concerned with super-Earths, observations of which are rapidly developing. We calculated evolution of temperature distributions in planetary interior, using Vinet equations of state, Arrhenius-type formula for mantle viscosity, and the astrophysical mixing length theory for convective heat transfer modified for mantle convection. After calibrating the model with terrestrial planets in the Solar system, we apply it for 0.1--$10M_{\\oplus}$ rocky planets with surface temperature of $300~\\mbox{K}$ (in habitable zones) and the Earth-like compositions. With the criterion for heat flux at the CMB (core-mantle boundary), the lifetime of the magnetic fields is evaluated from the calculated thermal evolution. We found that the lifetime slowly incr...

  17. Magnetic structure, magnetoelastic coupling, and thermal properties of EuCrO3 nanopowders

    Science.gov (United States)

    Taheri, M.; Razavi, F. S.; Yamani, Z.; Flacau, R.; Reuvekamp, P. G.; Schulz, A.; Kremer, R. K.

    2016-03-01

    We carried out detailed studies of the magnetic structure, magnetoelastic coupling, and thermal properties of EuCrO3 nanopowders from room temperature to liquid helium temperature. Our neutron powder diffraction and x-ray powder diffraction measurements provide precise atomic positions of all atoms in the cell, especially for the light oxygen atoms. The low-temperature neutron powder diffraction data revealed extra Bragg peaks of magnetic origin, which can be attributed to a Gx antiferromagnetic structure with an ordered moment of ˜2.4 μB consistent with the 3 d3 electronic configuration of the Cr3 + cations. Apart from previously reported antiferromagnetic and ferromagnetic transitions in EuCrO3 at low temperatures, we also observed an anomaly at about 100 K. This anomaly was observed in the temperature dependence of the sample's, lattice parameters, thermal expansion, Raman spectroscopy, permittivity, and conductance measurements. This anomaly is attributed to the magnetoelastic distortion in the EuCrO3 crystal.

  18. Analytical study of induced magnetic and thermal stress in superconducting solenoid

    International Nuclear Information System (INIS)

    VECC is in a process of developing an ISOL type of Rare Isotope Beam Facility. After RFQ and Drift Tube Linacs, superconducting QWRs will be employed to accelerate the beam up to 7 MeV/u energy. At present design work has been just initiated for the development of first cryomodule consisting of 4 numbers of superconducting QWR. A superconducting solenoid is planned to put in the middle of the 4 numbers of QWRs for the transverse focusing of the beam. After carrying out preliminary electromagnetic design of the solenoid for producing 9T magnetic field, mechanical design has also been started. Design of the bucking coil has also been carried out for the solenoid so that stray filed at a distance of 200 mm from the centre is less than 30 mT otherwise niobium made cavities of the QWR would have been quenched at underrated electric field gradient. Analytical stress analysis has been carried out to evaluate the stress induced due to magnetic pressure and thermal contraction. Analysis is still in progress to evaluate the necessity of requirement of banding to be carried out with material having higher thermal expansion coefficient so that contact of the extreme layer of the cable has been ensured. Alternative to the provision of availing banding, analysis is underway to take care of the situation by pre-stressing the cable itself during the winding of the coil. (author)

  19. Coupled granular/continuous medium for thermally stable perpendicular magnetic recording

    International Nuclear Information System (INIS)

    We studied coupled granular/continuous (CGC) perpendicular media consisting of a continuous multilayer structure and a granular layer. The addition of Co/Pt multilayers decreased the nucleation field from 200 to -1800 Oe and increased the squareness from 0.9 to 1.0. The moment decay at room temperature was significantly reduced from -4.8% to -0.05% per decade. At elevated temperatures, strong exchange coupling between a granular layer and a continuous layer is needed for thermal stability. The exchange-coupled continuous layer reduces thermal demagnetization as it effectively increases the grain size, tightens the grain distribution, and prevents the reversal of individual grains. Magnetic Force Microscope image showed a larger magnetic cluster size for the CGC structure. Compared to the CoCr18Pt12 medium, the CGC medium had 2.3 dB higher output. However, the noise for the CGC medium increased with the recording density, while the noise for the CoCr18Pt12 medium remained constant from 4 to 15 kfc/mm. Further optimization and noise reduction are still required for future high density recording

  20. Brief rapid thermal treatment effect on patterned CoFeB-based magnetic tunneling junctions

    Science.gov (United States)

    Wu, Kuo-Ming; Huang, Chao-Hsien; Wang, Yung-Hung; Kao, Ming-Jer; Tsai, Ming-Jinn; Wu, Jong-Ching; Horng, Lance

    2007-05-01

    The brief thermal treatment effects on the magnetoresistance of microstructured Co60Fe20B20-based magnetic tunneling junctions have been studied. The elliptical shape of devices with long/short axis of 4/2μm was patterned out of film stack of seed layer (20)/PtMn(15)/Co60Fe20B20(3)/Al(0.7)oxide/C60Fe20B20(20)/capping layer (48) (thickness unit in nanometers) combining conventional lithography and inductively coupled plasma reactive ion beam etching technologies. The thermal annealing was carried out with device loading into a furnace with preset temperatures ranging from 100to400°C for only 5min in the absence of any external magnetic field. The magnetoresistance was found to increase with increasing annealing temperatures up to 250°C and then decrease at higher annealing temperatures. In addition, the magnetoresistance ratio of around 35%, similar to that of as-fabricated devices, sustains up to annealing temperature of 350°C. This survival of magnetoresistance at higher annealing temperature is due to boron conservation in the amorphous CoFeB ferromagnetic layer at higher annealing temperature for only a short time, which is manifested using x-ray diffractometer technique.

  1. Evolution of structural and magnetic properties of amorphous CoFeB film with thermal annealing

    International Nuclear Information System (INIS)

    Evolution of structural and magnetic properties of amorphous Co68Fe14B18 thin film with thermal annealing has been studied. Initially, the film exhibits a structural relaxation as evidenced by annihilation of excess free volume and an increase in topological short range order. Annealing at 473 K results in precipitation of primary phase followed by formation of boride phase at a still higher temperature of 598 K. Iron preferentially precipitates out in the primary phase, resulting in the formation of bcc Co58Fe41. This suggests an affinity of Co towards B. Such affinity between Co and B is evidenced even in the as-deposited film, using hard x-ray photoelectron spectroscopy (HAXPES) measurements. As-deposited film exhibits an in-plane uniaxial magnetic anisotropy which disappears at a temperature well beyond crystallization temperature, suggesting that the origin of anisotropy is mainly a chemical short range order in the system. Variation in the coercivity with thermal annealing can be understood in terms of random anisotropy model. Precise measurement of Fe self-diffusion using neutron reflectivity shows that diffusion length associated with annihilation of excess free volume in the film is about 0.5 nm. This agrees with the length scale of structural fluctuations in amorphous alloys. Secondary ion mass spectrometry measurements show that thermal annealing results in depletion of B in the region of the interface with the substrate, with associated faster Fe diffusion in this region. This faster diffusion of Fe may be a possible cause of preferential crystallization of the film in the interfacial region as seen in some earlier studies

  2. Magnetic resonance-guided laser interstitial thermal therapy: report of a series of pediatric brain tumors.

    Science.gov (United States)

    Tovar-Spinoza, Zulma; Choi, Hoon

    2016-06-01

    OBJECTIVE Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) is a novel, minimally invasive treatment that has multiple advantages in pediatric use and broad applicability for different types of lesions. Here, the authors report the preliminary results of the first series of pediatric brain tumors treated with MRgLITT at Golisano Children's Hospital in Syracuse, New York. METHODS Pediatric brain tumors treated with MRgLITT between February 2012 and August 2014 at Golisano Children's Hospital were evaluated retrospectively. Medical records, radiological findings, surgical data, complications, and results of tumor volumetric analyses were reviewed. The Visualase thermal laser system (Medtronic) was used in all MRgLITT procedures. RESULTS This series included 11 patients with 12 tumors (pilocytic astrocytoma, ependymoma, medulloblastoma, choroid plexus xanthogranuloma, subependymal giant cell astrocytoma, and ganglioglioma). A single laser and multiple overlapping ablations were used for all procedures. The mean laser dose was 10.23 W, and the mean total ablation time was 68.95 seconds. The mean initial target volume was 6.79 cm(3), and the mean immediate post-ablation volume was 7.86 cm(3). The mean hospital stay was 3.25 days, and the mean follow-up time was 24.5 months. Tumor volume decreased in the first 3 months after surgery (n = 11; p = 0.007) and continued to decrease by the 4- to 6-month followup (n = 11; mean volume 2.61 cm(3); p = 0.009). Two patients experienced post-ablation complications: transient right leg weakness in one patient, and transient hemiparesis, akinetic mutism, and eye movement disorder in the other. CONCLUSIONS Magnetic resonance-guided laser interstitial thermal therapy is an effective first- or second-line treatment for select pediatric brain tumors. Larger multiinstitutional clinical trials are necessary to evaluate its use for different types of lesions to further standardize practices. PMID:26849811

  3. FTIR, magnetic, mass spectral, XRD and thermal studies of metal chelates of tenoxicam

    Science.gov (United States)

    Zayed, M. A.; El-Dien, F. A. Nour; Mohamed, Gehad G.; El-Gamel, Nadia E. A.

    2007-09-01

    Metal chelates of anti-inflammatory drug, tenoxicam (Ten), are synthesized and characterized using elemental analyses, IR, solid reflectance, magnetic, mass spectra, thermal analyses (TGA and DTA) and X-ray powder diffraction techniques. The chelates are found to have the general formulae [M(H 2L) 2(H 2O) x] (A) 2· yH 2O (where H 2L = neutral Ten, A = Cl in case of Ni(II) and Co(II) or AcO in case of Cu(II) and Zn(II) ions, x = 0-2 and y = 0-2.5) and [M(H 2L) 3](A) z· yH 2O (A = SO 4 in case of Fe(II) ion ( z = 1) or Cl in case of Fe(III) ( z = 3) and y = 0-4). IR spectra reveal that Ten behaves as a neutral bidentate ligand coordinated to the metal ions through the pyridyl- N and carbonyl- O of the amide moiety. The solid reflectance spectra and magnetic moment measurements reveal that these chelates have tetrahedral, square planar and octahedral geometrical structures. Mass spectra are also used to confirm the proposed formulae and the possible fragments resulted from fragmentation of Ten and its Zn(II) and Cu(II) chelates are suggested. The thermal behaviour of the chelates (TG/DTG, DTA) are discussed in detailed manner and revealed that water molecules of crystallization together with anions are removed in the first and second steps while the Ten molecules are removed in the subsequent steps. Different thermodynamic parameters are evaluated and the relative thermal stabilities of the complexes are discussed. X-ray powder diffraction patterns are used to indicate the polymorphic form of Ten and if the complexes have molecular similarity with respect to type of coordination.

  4. THERMAL EVOLUTION AND LIFETIME OF INTRINSIC MAGNETIC FIELDS OF SUPER-EARTHS IN HABITABLE ZONES

    International Nuclear Information System (INIS)

    We have numerically studied the thermal evolution of different-mass terrestrial planets in habitable zones, focusing on the duration of dynamo activity to generate their intrinsic magnetic fields, which may be one of the key factors in habitability of the planets. In particular, we are concerned with super-Earths, observations of which are rapidly developing. We calculated the evolution of temperature distributions in the planetary interior using Vinet equations of state, the Arrhenius-type formula for mantle viscosity, and the astrophysical mixing-length theory for convective heat transfer modified for mantle convection. After calibrating the model with terrestrial planets in the solar system, we apply it for 0.1-10 M+ rocky planets with a surface temperature of 300 K (in habitable zones) and Earth-like compositions. With the criterion of heat flux at the core-mantle boundary (CMB), the lifetime of the magnetic fields is evaluated from the calculated thermal evolution. We found that the lifetime slowly increases with planetary mass (Mp ), independent of the initial temperature gap at the CMB (ΔTCMB), but beyond the critical value Mc,p (∼O(1) M+) it abruptly declines from the mantle viscosity enhancement due to the pressure effect. We derived Mc,p as a function of ΔTCMB and a rheological parameter (activation volume, V*). Thus, the magnetic field lifetime of super-Earths with Mp >Mp,c sensitively depends on ΔTCMB, which reflects planetary accretion, and V*, which has uncertainty at very high pressure. More advanced high-pressure experiments and first-principle simulation, as well as planetary accretion simulation, are needed to discuss the habitability of super-Earths.

  5. 3D thermal analysis of a permanent magnet motor with cooling fans

    Institute of Scientific and Technical Information of China (English)

    Zheng TAN; Xue-guan SONG; Bing JI; Zheng LIU; Ji-en MA; Wen-ping CAO

    2015-01-01

    Overheating of permanent magnet (PM) machines has become a major technical challenge as it gives rise to magnet demagnetization, degradation of insulation materials, and loss of motor efficiency. This paper proposes a state-of-the-art cooling system for an axial flux permanent magnet (AFPM) machine with the focus on its structural optimization. A computational fluid dynamics (CFD) simulation with thermal consideration has been shown to be an efficient approach in the literature and is thus employed in this work. Meanwhile, a simplified numerical approach to the AFPM machine with complex configuration in 3D consisting of conduction, forced convection, and conjugate heat transfer is taken as a case study. Different simplification meth-ods (including configuration and working conditions) and two optimized fans for forced convection cooling are designed and installed on the AFPM machine and compared to a natural convection cooling system. The results show that the proposed ap-proach is effective for analyzing the thermal performance of a complex AFPM machine and strikes a balance between reasona-ble simplification, accuracy, and computational resource.%目的:提出一种适合永磁电机的冷却系统设计方案,降低电机本体温度。  创新点:提出一种适合永磁电机热分析的CFD仿真模型。  方法:采用计算流体动力学方法对包含冷却风扇的永磁电机进行空间三维热力学分析和优化设计。  结论:本文提出并优化后的冷却风扇可有效降低永磁电机的最高和平均温度。

  6. Thermal Design of an Nb3Sn High Field Accelerator Magnet

    CERN Document Server

    Pietrowicz, S

    2011-01-01

    Within the framework of the European project EuCARD, a Nb3Sn high field accelerator magnet is under design to serve as a test bed for future high field magnets and to upgrade the vertical CERN cable test facility, Fresca. The Fresca 2 block coil type magnet will be operated at 1.9 K or 4.2 K and is designed to produce about 13 T. A 2D numerical thermal model was developed to determinate the temperature margin of the coil in working conditions and the appropriate cool-down scenario. The temperature margin, which is DTmarge=5.8 K at 1.9 K and DTmarge=3.5 K at 4.2 K, was investigated in steady state condition with the AC losses due to field ramp rate as input heat generation. Several cool-down scenarios were examined in order to minimize the temperature difference and therefore reducing the mechanical constraints within the structure. The paper presents the numerical model, the assumptions taken for the calculations and several results of the simulation for the cool-down and temperature distributions due to seve...

  7. Structural, Optical, and Magnetic Characterization of Spinel Zinc Chromite Nanocrystallines Synthesised by Thermal Treatment Method

    Directory of Open Access Journals (Sweden)

    Salahudeen A. Gene

    2014-01-01

    Full Text Available The present study reports the structural and magnetic characterization of spinel zinc chromite (ZnCr2O4 nanocrystallines synthesized by thermal treatment method. The samples were calcined at different temperatures in the range of 773 to 973 K. Polyvinylpyrrolidone was used to control the agglomeration of the nanoparticles. The average particle size of the synthesized nanocrystals was determined by powder X-ray diffraction which shows that the crystallite size increases from 19 nm at 773 K to 24 nm at 973 K and the result was in good agreement with the transmission electron microscopy images. The elemental composition of the samples was determined by energy dispersed X-ray spectroscopy which confirmed the presence of Zn, Cr, and O in the final products. Fourier transform infrared spectroscopy also confirmed the presence of metal oxide bands for all the samples calcined at different temperature. The band gap energy was calculated from UV-vis reflectance spectra using the Kubelka-Munk function and the band gap energy of the samples was found to decrease from 4.03 eV at 773 K to 3.89 eV at 973 K. The magnetic properties were also demonstrated by electron spin resonance spectroscopy, the presence of unpaired electrons was confirmed, and the resonant magnetic field and the g-factor of the calcined samples were also studied.

  8. Hardening of Thermal Photons Through Inverse Compton Scattering in Strong Magnetic Fields

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A new spectrum function is obtained by use of the Compton scattering cross section in the laboratory frame derived earlier. This spectrum function, besides some modifications in the coefficients of the resonant term, contains also a non-resonant term which is inversely proportional to the square of the magnetic field. Based on this spectrum function, the hardening of thermal photons through inverse Compton scattering by relativistic electron beams on the surface of a strongly magnetized neutron star is investigated. Two new features are found. First, there is a maximum scattered photon energy for a given resonant scattering, beyond which resonance disappears. This maximum depends on the electron energy and the magnetic field, but is independent of the incident photon energy. Second, beyond each resonant scattering, there is a high-energy tail, resulting from non-resonant scattering. It is also found that all the tails have a common upper limit which is the highest scattered photon energy for the given incident photon and electron energies. These two new features are absent in the Monte Carlo simulations and therefore, may have physical implications for γγ-ray emissions.

  9. Magnetic field effect on laminar heat transfer in a pipe for thermal entry region

    International Nuclear Information System (INIS)

    The influence of a transverse magnetic field on the local heat transfer of an electrically-conducting laminar fluid flow with high Prandtl number through a pipe was studied experimentally. Experiments indicated an increase in the local Nusselt number. The coupled set of the equations of motion and the energy equation including the viscous and Joule dissipation terms becomes non-linear and is solved numerically using a finite difference scheme. Favorable comparisons with experimental results confirm the correctness of the numerical results. It is found that the influence of magnetic field can be diminished by reducing the angle between the flow direction and the direction of magnetic field. The wall temperature reduces as the value of Hartmann number increases and the reduction rate of the wall temperature decreases as the value of Hartmann number exceeds a certain value. The average Nusselt number asymptotically approaches its limit as the Hartmann number becomes larger. Also, curve fitting can be employed to derive an equation for the average Nusselt number as a function of the Hartmann number. This equation is similar to the Sieder-Tate equation. It is observed that increasing the Hartmann number has no considerable effect on the thermal boundary layer thickness but decreases the temperature of fluid layers inside the boundary layer

  10. Microwaves in Airborne Surveillance

    OpenAIRE

    Christopher, S.

    2013-01-01

    The use of microwave spectrum is widespread due to its convenience. Therefore, enormous amount of information is available in the free space channel. Obviously, mining this channel for surveillance is quite common. Airborne surveillance offers significant advantages in military operations. This paper talks of the usage of microwaves in airborne surveillance systems, in general, and in the Indian airborne early warning and control (AEW&C) System, in particular. It brings out the multiple s...

  11. Interaction of supra-thermal ions with turbulence in a magnetized toroidal plasma

    International Nuclear Information System (INIS)

    This thesis addresses the interaction of a supra-thermal ion beam with turbulence in the simple magnetized toroidal plasma of TORPEX. The first part of the Thesis deals with the ohmic assisted discharges on TORPEX. The aim of these discharges is the investigation of the open to closed magnetic field line transition. The relevant magnetic diagnostics were developed. Ohmic assisted discharges with a maximum plasma current up to 1 kA are routinely obtained. The equilibrium conditions on the vacuum magnetic field configuration were investigated. In the second part of the Thesis, the design of the fast ion source and detector are discussed. The accelerating electric field needed for the fast ion source was optimized. The fast ion source was constructed and commissioned. To detect the fast ions a specially designed gridded energy analyzer was used. The electron energy distribution function was obtained to demonstrate the efficiency of the detector. The experiments with the fast ion beam were conducted in different plasma regions of TORPEX. In the third part of the Thesis, numerical simulations are used to interpret the measured fast ion beam behavior. It is shown that a simple single particle equation of motion explains the beam behavior in the experiments in the absence of plasma. To explain the fast ion beam experiments with the plasma a turbulent electric field must be used. The model that takes into account this turbulent electrical field qualitatively explains the shape of the fast ion current density profile in the different plasma regions of TORPEX. The vertically elongated fast ion current density profiles are explained by a spread in the fast ion velocity distribution. The theoretically predicted radial fast ion beam spreading due to the turbulent electric field was observed in the experiment. (author)

  12. Magnetic and thermal behaviour of the amorphous ferromagnet Fe79B16Si5

    International Nuclear Information System (INIS)

    Spin waves in the amorphous ferromagnet Fe79B16Si5 are studied by Moessbauer effect spectroscopy. The magnetic hyperfine field (MHF) is measured at the Fe sites of such a ferromagnet, which exhibits a temperature dependence of the form, H(T)/H(0) = (1 - BT/sup 3/2/ - CT/sup 5/2/), indicative of spin wave excitations in amorphous ferromagnets. The T/sup 3/2/ behaviour and the distribution of the exchange interactions are studied in detail as a function of the MHF. The spin wave excitations constant B/sub 3/2/ = BT/sub C//sup 3/2/ = 0.3 +- 0.05 and C/sub 5/2/ = CT/sub C//sup 5/2/ = 0.3 +- 0.05,Are obtained by fitting the experimental data, and where T/sub C/ = 670 K. The results sh=ow that the contribution of C/sub 5/2/ is extremely effective above 124 K, while the ratio C/sub 5/2//C/sub 3/2/ = 1.0 indicates that the present magnetic interaction is of long range order character. On the other hand, fluctuations of the exchange interaction constant are found to decrease with increasing temperature. Some information regarding the directions of the magnetic moments are obtained during the study of the magnetic anisotropy course. The values of the Einstein and Debye temperatures as measured from the thermal shift results are theta/sub E/ = 250 K and theta/sub D/ = 350 K,And from the Moessbauer factor measurements theta/sub E/ = 165 K and theta/sub D/ = 285 K. (autho=r)

  13. Airborne system for mapping and tracking extended gamma ray sources

    International Nuclear Information System (INIS)

    An airborne system was developed for mapping and tracking extended sources of airborne or terrestrially distributed γ-ray emitters. The system records 300 channel γ-ray spectral data every three seconds on magnetic tape. Computer programs have been written to isolate the contribution from the particular radionuclide of interest. Aircraft position as sensed by a microwave ranging system is recorded every second on magnetic tape. Measurements of airborne stack releases of 41A concentrations versus time or aircraft position agree well with computer code predictions

  14. System considerations for airborne, high power superconducting generators

    International Nuclear Information System (INIS)

    The design of rotating superconducting field windings in high power generators is greatly influenced by system considerations. Experience with two superconducting generators designed to produce 5 and 20 Mw resulted in a number of design restrictions. The design restrictions imposed by system considerations have not prevented low weight and high voltage power generation capability. The application of multifilament Nb;sub 3;Sn has permitted a large thermal margin to be designed into the rotating field winding. This margin permits the field winding to remain superconducting under severe system operational requirements. System considerations include: fast rotational startup, fast ramped magnetic fields, load induced transient fields and airborne cryogen logistics. Preliminary selection of a multifilament Nb;sub 3;Sn cable has resulted from these considerations. The cable will carry 864 amp at 8.5K and 6.8 Tesla. 10 refs

  15. Processing of Mn-Al nanostructured magnets by spark plasma sintering and subsequent rapid thermal annealing

    Science.gov (United States)

    Saravanan, P.; Vinod, V. T. P.; Černík, Miroslav; Selvapriya, A.; Chakravarty, Dibyendu; Kamat, S. V.

    2015-01-01

    The potential of spark plasma sintering (SPS) in combination with rapid thermal annealing (RTA) for the processing of Mn-Al nanostructured magnets is explored in this study. Ferromagnetic α-Mn alloy powders were processed by high-energy ball milling using Mn (56 at%) and Al (44 at%) as constituent metal elements. The alloying action between Mn and Al due to intensive milling was studied by X-ray diffraction and field-emission scanning electron microscope; while the phase transformation kinetics was investigated using differential scanning calorimetry. The evolution of ferromagnetic properties in the as-milled powders was studied by superconducting quantum interference device (SQUID). Among the Mn-Al alloy powders collected at various milling intervals, the 25 h milled Mn-Al powders showed a good combination of coercivity, Hc (11.3 kA/m) and saturation magnetization, Ms (5.0 A/m2/kg); accordingly, these powders were chosen for SPS. The SPS experiments were conducted at different temperatures: 773, 873 and 973 K and its effect on the density, phase composition and magnetic properties of the Mn-Al bulk samples were investigated. Upon increasing the SPS temperature from 773 to 973 K, the bulk density was found to increase from 3.6 to 4.0 g/cm3. The occurrence of equilibrium β-phase with significant amount of γ2-phase was obvious at all the SPS temperatures; however, crystallization of some amount of τ-phase was evident at 973 K. Irrespective of the SPS temperatures, all the samples demonstrated soft magnetic behavior with Hc and Ms values similar to those obtained for the 25 h milled powders. The magnetic properties of the SPSed samples were significantly improved upon subjecting them to RTA at 1100 K. Through the RTA process, Hc values of 75, 174 and 194 kA/m and Ms values of 19, 21 and 28 A/m2/kg were achieved for the samples SPSed at 773, 873 and 973 K, respectively. The possible reasons for the observed improvement in the magnetic properties of the SPSed

  16. The calculation of the thermal properties of graphene under a magnetic field via the two-dimensional Dirac oscillator

    OpenAIRE

    Boumali, Abdelmalek.

    2014-01-01

    In this paper, we show, by using the approach of effective mass, that the model of a two-dimensional Dirac oscillator can be used to describe the thermal properties of graphene under an uniform magnetic field. All thermal quantities of graphene, such as the free energy, the mean energy, the entropy and the specific heat, have been found by using an approach based on the zeta function.

  17. Magnetic, Thermal and Dynamical Evolution of AN M3.2 Two-Ribbon Flare

    Science.gov (United States)

    Collados, Manuel; Kuckein, Christoph; Manso Sainz, Rafael; Asensio Ramos, Andres

    On 2013, 17th May, a two-ribbon M3.2 flare took place in the solar atmosphere on the active region AR 11748. The flare evolution was observed at the German VTT of the Observatorio del Teide using the instrument TIP-II, with spectropolarimetric measurements of the photosphere (Si I at 1082.7 nm) and the chromosphere (Helium triplet at 1083 nm). Simultaneous spectroscopic data of the chromospheric spectral line of Ca II at 854.2 nm and filtergrams at Halpha were also obtained. The flare evolution as observed from the ground can be compared with the changes observed by AIA@SDO at different ultraviolet wavelengths. The ground observations covered several hours, including the pre-flare, impulsive, gradual and post-flare phases. We present maps of the magnetic field, thermal and dynamical properties of the region during its evolution from pre- to post-flare phase.

  18. Preparation and thermal stability of nickel nanowires via self-assembly process under magnetic field

    Indian Academy of Sciences (India)

    Hu Wang; Ming Li; Xiaoyu Li; Kenan Xie; Li Liao

    2015-09-01

    Nickel nanowires were synthesized via a template-free method in an aqueous solution system combined with chemical reduction and magnetic field. The suitable concentration of Ni ions and reaction time were controlled in order to obtain nickel wires with uniform sizes. The products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermogravimetry and differential scanning calorimetry. The results showed that the Ni nanowires with large aspect ratio up to 200 had uniform size and morphology, about 200 nm. Especially, it is noteworthy that the samples were stable in air when the temperature was lower than 318°C. The study would provide a facile method to prepare nickel nanowires with homogeneous diameter and high thermal stability, which could be used in catalysing CO2 hydrogenation.

  19. Thermal annealing and magnetic anisotropy of NiFe thin films on n{sup +}-Si for spintronic device applications

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Q.H. [School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Department of Physics, Semiconductor Photonics Research Center, Xiamen University, Xiamen 361005, People’s Republic of China (China); Gansu Key Laboratory of Sensor and Sensor Technology, Institute of Sensor Technology, Gansu Academy of Science, Lanzhou 730000 (China); Huang, R. [Department of Physics, Semiconductor Photonics Research Center, Xiamen University, Xiamen 361005, People’s Republic of China (China); Wang, L.S. [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China); Wu, Z.G., E-mail: zgwu@lzu.edu.cn [School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Li, C., E-mail: lich@xmu.edu.cn [Department of Physics, Semiconductor Photonics Research Center, Xiamen University, Xiamen 361005, People’s Republic of China (China); Luo, Q. [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China); Zuo, S.Y. [School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Li, J. [Department of Physics, Semiconductor Photonics Research Center, Xiamen University, Xiamen 361005, People’s Republic of China (China); Peng, D.L. [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China); Han, G.L. [Gansu Key Laboratory of Sensor and Sensor Technology, Institute of Sensor Technology, Gansu Academy of Science, Lanzhou 730000 (China); Yan, P.X. [School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China)

    2015-11-15

    To ensure that the magnetic metal electrodes can meet the requirements of the spin injection, NiFe films prepared both on HfO{sub 2} dielectric layer and n{sup +}-Si directly by sputtering deposition, and treated by conventional furnace annealing and/or high vacuum magnetic field annealing were investigated. It was found that thermal annealing at 250 °C improved the crystalline quality and reduced surface roughness of the NiFe films, thus enhancing its saturation magnetization intensity. The 100 nm thick NiFe films had too large coercive force and saturation magnetization intensity in vertical direction to meet the requirements of Hanle curve detection. While, 30 nm thick NiFe films showed paramagnetic hysteresis loops in vertical direction, and the magnetization intensity of the sample after annealing at 250 °C for 30 min was less than 2% to the parallel when the external magnetic field was given between ±10 Oe. This was preferred to Hanle curve detection. The thin HfO{sub 2} dielectric layer between metal and Si partially suppressed the diffusion of Ni in NiFe into Si substrate and formation of NiSi, greatly enhancing the saturation magnetization intensity of the Al/NiFe/HfO{sub 2}/Si sample by thermal annealing. Those results suggest that Al/NiFe/HfO{sub 2}/Si structure, from the point view of magnetic electrodes, would be suitable for spin injection and detection applications. - Highlights: • The saturation magnetization intensity of NiFe thin-film was enhanced by thermal annealing. • A paramagnetic hysteresis loop of NiFe thin-film was observed in vertical direction. • The thin HfO{sub 2} dielectric layer between NiFe and Si partially suppressed the diffusion of Ni into Si.

  20. Thermal annealing and magnetic anisotropy of NiFe thin films on n+-Si for spintronic device applications

    International Nuclear Information System (INIS)

    To ensure that the magnetic metal electrodes can meet the requirements of the spin injection, NiFe films prepared both on HfO2 dielectric layer and n+-Si directly by sputtering deposition, and treated by conventional furnace annealing and/or high vacuum magnetic field annealing were investigated. It was found that thermal annealing at 250 °C improved the crystalline quality and reduced surface roughness of the NiFe films, thus enhancing its saturation magnetization intensity. The 100 nm thick NiFe films had too large coercive force and saturation magnetization intensity in vertical direction to meet the requirements of Hanle curve detection. While, 30 nm thick NiFe films showed paramagnetic hysteresis loops in vertical direction, and the magnetization intensity of the sample after annealing at 250 °C for 30 min was less than 2% to the parallel when the external magnetic field was given between ±10 Oe. This was preferred to Hanle curve detection. The thin HfO2 dielectric layer between metal and Si partially suppressed the diffusion of Ni in NiFe into Si substrate and formation of NiSi, greatly enhancing the saturation magnetization intensity of the Al/NiFe/HfO2/Si sample by thermal annealing. Those results suggest that Al/NiFe/HfO2/Si structure, from the point view of magnetic electrodes, would be suitable for spin injection and detection applications. - Highlights: • The saturation magnetization intensity of NiFe thin-film was enhanced by thermal annealing. • A paramagnetic hysteresis loop of NiFe thin-film was observed in vertical direction. • The thin HfO2 dielectric layer between NiFe and Si partially suppressed the diffusion of Ni into Si

  1. MHD stagnation point flow toward a linearly-stretching thermally-insulated sheet with induced magnetic field

    CERN Document Server

    El-Mistikawy, Tarek M A

    2016-01-01

    The equations governing the magnetohydrodynamic stagnation point flow toward a non-conducting, thermally insulated, nonporous, linearly stretching sheet are cast in a self similar form. Consistent boundary conditions on the velocity, magnetic field and temperature are invoked. The flow problem involves three parameters- the magnetic Prandtl number, the magnetic interaction number, and the ratio of the stretching rate to the strength of the stagnation point flow. The energy equation includes viscous dissipation and Joule heating, and introduces the Prandtl number as a fourth parameter. Numerical solutions are obtained and sample results are presented.

  2. Thermal plasma processed ferro-magnetically ordered face-centered cubic iron at room temperature

    International Nuclear Information System (INIS)

    Here, we report tailor made phase of iron nanoparticles using homogeneous gas phase condensation process via thermal plasma route. It was observed that crystal lattice of nano-crystalline iron changes as a function of operating parameters of the plasma reactor. In the present investigation iron nanoparticles have been synthesized in presence of argon at operating pressures of 125–1000 Torr and fixed plasma input DC power of 6 kW. It was possible to obtain pure fcc, pure bcc as well as the mixed phases for iron nanoparticles in powder form as a function of operating pressure. The as synthesized product was characterized for understanding the structural and magnetic properties by using X-ray diffraction, vibrating sample magnetometer, and Mössbauer spectroscopy. The data reveal that fcc phase is ferromagnetically ordered with high spin state, which is unusual whereas bcc phase is found to be ferromagnetic as usual. Finally, the structural and magnetic properties are co-related.

  3. Thermal stability and magnetic properties of Fe-Co-B-Si-Nb glassy alloys

    International Nuclear Information System (INIS)

    The fully glassy rods of [(FexCo1-x)0.75Si0.05B0.25]94Nb6 alloys (x=0.4, 0.5 and 0.6) in diameters up to 2 mm were produced by copper mold casting. The effect of Fe substitution in these glassy alloys on thermal stability and melting behavior were studied by differential scanning calorimetry. Phase evolution of the glassy alloys during heating crystallization process was evaluated using X-rays diffraction. The first crystallization stage results in the precipitation of metastable (Fe,Co)23B6 crystalline phase in the glassy alloys. The behaviour of the glassy alloys in DC applied field was investigated by means of vibrating sample magnetometer. The investigated samples are soft magnetic. Further, the influence of crystallization on the saturation magnetization (Ms), coercivity (Hc) and Curie temperature (Tc) were evaluated, which indicated that (Fe,Co)23B6 phase can improve the Ms and Tc, while also increase the Hc.

  4. Asymmetric and Negative Differential Thermal Spin Effect at Magnetic Interfaces: Towards Spin Seebeck Diodes and Transistors

    Science.gov (United States)

    Ren, Jie; Zhu, Jian-Xin

    2014-03-01

    We study the nonequilibrium thermal-spin transport across metal-magnetic insulator interfaces. The transport is assisted by the exchange interaction between conduction electrons in the metal and localized spins in the magnetic insulator. We predict the rectification and negative differential spin Seebeck effect (SSE), that is, reversing the temperature bias is able to give asymmetric spin currents and increasing temperature bias could give an anomalously decreasing spin current. We resolve their microscopic mechanism as a consequence of the energy-dependent electronic DOS in the metal. The rectification of spin Peltier effect is also discussed. We then study the asymmetric and negative differential magnon tunneling driven by temperature bias. We show that the many-body magnon interaction that makes the magnonic spectrum temperature-dependent is the crucial factor for the emergence of rectification and negative differential SSEs in magnon tunneling junctions. We show that these asymmetric and negative differential SSEs are relevant for building magnon and spin Seebeck diodes and transistors, which could play important roles in controlling information and energy in functional devices. Supported by the National Nuclear Security Administration of the US DOE at LANL under Contract No. DE-AC52-06NA25396.

  5. Thermal plasma processed ferro-magnetically ordered face-centered cubic iron at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Raut, Suyog A.; Kanhe, Nilesh S.; Bhoraskar, S. V.; Mathe, V. L., E-mail: vlmathe@physics.unipune.ac.in [Department of Physics, Savitribai Phule Pune University, Pune 411007 (India); Das, A. K. [Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

    2014-10-28

    Here, we report tailor made phase of iron nanoparticles using homogeneous gas phase condensation process via thermal plasma route. It was observed that crystal lattice of nano-crystalline iron changes as a function of operating parameters of the plasma reactor. In the present investigation iron nanoparticles have been synthesized in presence of argon at operating pressures of 125–1000 Torr and fixed plasma input DC power of 6 kW. It was possible to obtain pure fcc, pure bcc as well as the mixed phases for iron nanoparticles in powder form as a function of operating pressure. The as synthesized product was characterized for understanding the structural and magnetic properties by using X-ray diffraction, vibrating sample magnetometer, and Mössbauer spectroscopy. The data reveal that fcc phase is ferromagnetically ordered with high spin state, which is unusual whereas bcc phase is found to be ferromagnetic as usual. Finally, the structural and magnetic properties are co-related.

  6. Processing of Mn–Al nanostructured magnets by spark plasma sintering and subsequent rapid thermal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Saravanan, P., E-mail: psdrdo@gmail.com [Defence Metallurgical Research Laboratory, Hyderabad 500058 (India); Vinod, V.T.P.; Černík, Miroslav [Institute for Nanomaterials, Advanced Technologies and Innovation, Department of Natural Sciences, Technical University of Liberec, Studentská 1402/2, 461 17 Liberec 1 (Czech Republic); Selvapriya, A. [Defence Metallurgical Research Laboratory, Hyderabad 500058 (India); Sri Ramakrishna Engineering College, Coimbatore 641022 (India); Chakravarty, Dibyendu [International Advanced Research Centre for Powder Metallurgy and New Materials, Hyderabad 500005 (India); Kamat, S.V. [Defence Metallurgical Research Laboratory, Hyderabad 500058 (India)

    2015-01-15

    The potential of spark plasma sintering (SPS) in combination with rapid thermal annealing (RTA) for the processing of Mn–Al nanostructured magnets is explored in this study. Ferromagnetic α-Mn alloy powders were processed by high-energy ball milling using Mn (56 at%) and Al (44 at%) as constituent metal elements. The alloying action between Mn and Al due to intensive milling was studied by X-ray diffraction and field-emission scanning electron microscope; while the phase transformation kinetics was investigated using differential scanning calorimetry. The evolution of ferromagnetic properties in the as-milled powders was studied by superconducting quantum interference device (SQUID). Among the Mn–Al alloy powders collected at various milling intervals, the 25 h milled Mn–Al powders showed a good combination of coercivity, H{sub c} (11.3 kA/m) and saturation magnetization, M{sub s} (5.0 A/m{sup 2}/kg); accordingly, these powders were chosen for SPS. The SPS experiments were conducted at different temperatures: 773, 873 and 973 K and its effect on the density, phase composition and magnetic properties of the Mn–Al bulk samples were investigated. Upon increasing the SPS temperature from 773 to 973 K, the bulk density was found to increase from 3.6 to 4.0 g/cm{sup 3}. The occurrence of equilibrium β-phase with significant amount of γ{sub 2}-phase was obvious at all the SPS temperatures; however, crystallization of some amount of τ-phase was evident at 973 K. Irrespective of the SPS temperatures, all the samples demonstrated soft magnetic behavior with H{sub c} and M{sub s} values similar to those obtained for the 25 h milled powders. The magnetic properties of the SPSed samples were significantly improved upon subjecting them to RTA at 1100 K. Through the RTA process, H{sub c} values of 75, 174 and 194 kA/m and M{sub s} values of 19, 21 and 28 A/m{sup 2}/kg were achieved for the samples SPSed at 773, 873 and 973 K, respectively. The possible reasons for the

  7. Processing of Mn–Al nanostructured magnets by spark plasma sintering and subsequent rapid thermal annealing

    International Nuclear Information System (INIS)

    The potential of spark plasma sintering (SPS) in combination with rapid thermal annealing (RTA) for the processing of Mn–Al nanostructured magnets is explored in this study. Ferromagnetic α-Mn alloy powders were processed by high-energy ball milling using Mn (56 at%) and Al (44 at%) as constituent metal elements. The alloying action between Mn and Al due to intensive milling was studied by X-ray diffraction and field-emission scanning electron microscope; while the phase transformation kinetics was investigated using differential scanning calorimetry. The evolution of ferromagnetic properties in the as-milled powders was studied by superconducting quantum interference device (SQUID). Among the Mn–Al alloy powders collected at various milling intervals, the 25 h milled Mn–Al powders showed a good combination of coercivity, Hc (11.3 kA/m) and saturation magnetization, Ms (5.0 A/m2/kg); accordingly, these powders were chosen for SPS. The SPS experiments were conducted at different temperatures: 773, 873 and 973 K and its effect on the density, phase composition and magnetic properties of the Mn–Al bulk samples were investigated. Upon increasing the SPS temperature from 773 to 973 K, the bulk density was found to increase from 3.6 to 4.0 g/cm3. The occurrence of equilibrium β-phase with significant amount of γ2-phase was obvious at all the SPS temperatures; however, crystallization of some amount of τ-phase was evident at 973 K. Irrespective of the SPS temperatures, all the samples demonstrated soft magnetic behavior with Hc and Ms values similar to those obtained for the 25 h milled powders. The magnetic properties of the SPSed samples were significantly improved upon subjecting them to RTA at 1100 K. Through the RTA process, Hc values of 75, 174 and 194 kA/m and Ms values of 19, 21 and 28 A/m2/kg were achieved for the samples SPSed at 773, 873 and 973 K, respectively. The possible reasons for the observed improvement in the magnetic properties of the

  8. MOA: Magnetic Field Oscillating Amplified Thruster and its Application for Nuclear Electric and Thermal Propulsion

    International Nuclear Information System (INIS)

    More than 60 years after the later Nobel laureate Hannes Alfven had published a letter stating that oscillating magnetic fields can accelerate ionised matter via magneto-hydrodynamic interactions in a wave like fashion, the technical implementation of Alfven waves for propulsive purposes has been proposed, patented and examined for the first time by a group of inventors. The name of the concept, utilising Alfven waves to accelerate ionised matter for propulsive purposes, is MOA - Magnetic field Oscillating Amplified thruster. Alfven waves are generated by making use of two coils, one being permanently powered and serving also as magnetic nozzle, the other one being switched on and off in a cyclic way, deforming the field lines of the overall system. It is this deformation that generates Alfven waves, which are in the next step used to transport and compress the propulsive medium, in theory leading to a propulsion system with a much higher performance than any other electric propulsion system. Based on computer simulations, which were conducted to get a first estimate on the performance of the system, MOA is a highly flexible propulsion system, whose performance parameters might easily be adapted, by changing the mass flow and/or the power level. As such the system is capable to deliver a maximum specific impulse of 13116 s (12.87 mN) at a power level of 11.16 kW, using Xe as propellant, but can also be attuned to provide a thrust of 236.5 mN (2411 s) at 6.15 kW of power. While space propulsion is expected to be the prime application for MOA and is supported by numerous applications such as Solar and/or Nuclear Electric Propulsion or even as an 'afterburner system' for Nuclear Thermal Propulsion, other terrestrial applications can be thought of as well, making the system highly suited for a common space-terrestrial application research and utilisation strategy. (authors)

  9. The divergence of neighboring magnetic field lines and fast-particle diffusion in strong magnetohydrodynamic turbulence, with application to thermal conduction in galaxy clusters

    OpenAIRE

    Maron, Jason L.; Chandran, Benjamin D. G.; Blackman, Eric G.

    2003-01-01

    We investigate field-line separation in strong MHD turbulence using direct numerical simulations. We find that in the static-magnetic-field approximation the thermal conductivity in galaxy clusters is reduced by a factor of about 50 relative to the Spitzer thermal conductivity of a non-magnetized plasma. This value is too small for heat conduction to balance radiative cooling in clusters.

  10. Effect of magnetic and thermal properties of iron oxide nanoparticles (IONs) in nitrile butadiene rubber (NBR) latex

    International Nuclear Information System (INIS)

    Nitrile butadiene rubber (NBR) gloves are one of the most important personal protective equipments but they are possible to tear off and contaminate food or pharmaceutical and healthcare products during manufacturing and packaging process. High tendency of torn glove remaining in food or products due to white or light flesh-coloured glove is not easy to be detected by naked eyes. In this paper, iron oxide nanoparticles (IONs) selected as additive for NBR to improve its detectability by mean of magnetic properties. IONs synthesized via precipitation method and compounded with NBR latex before casting on petri dish. The properties of IONs were investigated by X-ray Diffractometry (XRD), Transmission Electron Microscope (TEM), Raman Spectroscopy and Vibrating Sample Magnetometer (VSM). Meanwhile NBR/IONs composites were studied by Thermogravimetry Analysis (TGA), Differential Scanning Calorimetry (DSC) and Vibrating Sample Magnetometer (VSM). It observed that, synthesized IONs shows of 25.28 nm crystallite with 25.86 nm semipherical (changed as) shape. Meanwhile, Magnetite and maghemite phase are found in range of 670 cm−1 and 700 cm−1 respectively, which it contributes magnetization saturation of 73.96 emu/g at 10,000 G by VSM. Thermal stability and magnetic properties were increased with incorporating IONs into NBR latex up to 20 phr. NBR/IONs 5 phr has the optimum thermal stability, lowest glass transition temperature (−14.83 °C) and acceptable range of magnetization saturation (3.83 emu/g at 10,000 G) to form NBR gloves with magnetic detectability. - Highlights: • We synthesized IONs with high magnetization saturation (Ms). • High Ms of IONs were incorporated into NBR latex in order to induce magnetic properties in the NBR composite. • Introduction of IONs into NBR latex would improve thermal properties. • The produced NBR/IONs 5 phr composite exceeded the minimum magnetic moment sensor of the detector. • They have high potential for the

  11. Dendritic flux avalanches and the accompanied thermal strain in type-II superconducting films: effect of magnetic field ramp rate

    Science.gov (United States)

    Jing, Ze; Yong, Huadong; Zhou, You-He

    2015-07-01

    Dendritic flux avalanches and the accompanying thermal stress and strain in type-II superconducting thin films under transverse magnetic fields are numerically simulated in this paper. The influence of the magnetic field ramp rate, edge defects, and the temperature of the surrounding coolant are considered. Maxwell's equations and the highly nonlinear E-J power-law characteristics of superconductors, coupled with the heat diffusion equation, are adopted to formulate these phenomena. The fast Fourier transform-based iteration scheme is used to track the evolution of the magnetic flux and the temperature in the superconducting film. The finite element method is used to analyze the thermal stress and strain induced in the superconducting film. It is found that the ramp rate has a significant effect on the flux avalanche process. The avalanches nucleate more easily for a film under a large magnetic field ramp rate than for a film under a small one. In addition, the avalanches always initiate from edge defects or areas that experience larger magnetic fields. The superconducting films experience large thermal strain induced by the large temperature gradient during the avalanche process, which may even lead to the failure of the sample.

  12. Suppression of parallel transport in turbulent magnetized plasmas and its impact on non-thermal and thermal aspects of solar flares

    CERN Document Server

    Bian, Nicolas H; Emslie, A Gordon

    2016-01-01

    The transport of the energy contained in electrons, both thermal and suprathermal, in solar flares plays a key role in our understanding of many aspects of the flare phenomenon, from the spatial distribution of hard X-ray emission to global energetics. Motivated by recent {\\em RHESSI} observations that point to the existence of a mechanism that confines electrons to the coronal parts of flare loops more effectively than Coulomb collisions, we here consider the impact of pitch-angle scattering off turbulent magnetic fluctuations on the parallel transport of electrons in flaring coronal loops. It is shown that the presence of such a scattering mechanism in addition to Coulomb collisional scattering can significantly reduce the parallel thermal and electrical conductivities relative to their collisional values. We provide illustrative expressions for the resulting thermoelectric coefficients that relate the thermal flux and electrical current density to the temperature gradient and the applied electric field. We...

  13. Changes in the magnetic and mechanical properties of thermally aged Fe–Cu alloys due to nano-sized precipitates

    International Nuclear Information System (INIS)

    The changes in the magnetic properties, mechanical properties, and microstructural parameters of Fe–Cu alloys due to thermal aging have been investigated to improve the fundamental understanding of using magnetic technology for the nondestructive evaluation (NDE) of irradiation embrittlement in the reactor pressure vessel (RPV). Nano-sized Cu particles precipitated from a Fe matrix after thermal aging at 500 °C for various times, and the microstructure parameters were determined. The coercivity, Barkhausen noise (BN), Vickers hardness, and yield stress were also measured for these samples. These properties show the same hardening–softening trend with increasing aging time, which can be interpreted in terms of the microstructure parameters evolution based on the model of the pinning of precipitates on domain walls and dislocations. These results suggest the practicability of using magnetic technology for the NDE of the irradiation embrittlement of the RPV. (paper)

  14. Airborne wind energy

    CERN Document Server

    Ahrens, Uwe; Schmehl, Roland

    2013-01-01

    This reference offers an overview of the field of airborne wind energy. As the first book of its kind, it provides a consistent compilation of the fundamental theories, a compendium of current research and development activities as well as economic and regulatory aspects. In five parts, the book demonstrates the relevance of Airborne Wind Energy and the role that this emerging field of technology can play for the transition towards a renewable energy economy. Part I on 'Fundamentals' contains seven general chapters explaining the principles of airborne wind energy and its different variants, o

  15. Effects of the magnetic field over the nanometric growth morphology on the material synthesis in a liquid spray thermal plasma reactor

    International Nuclear Information System (INIS)

    It is possible that the magnetic field affect the growth morphology of the materials at nanometric scale while there are synthesized. In this work is developed a thermal plasma reactor in fluidized bed assisted by magnetic mirror for material synthesis using a liquid spray. An aluminum solution is carrier in the plasma reactor with a without magnetic external magnetic field applied. We found from the characterization of material synthesized that: Aluminum nanowire and alumina nanofiber are generated when the external magnetic mirror is applied to the thermal plasma reactor.

  16. Analysis of airborne pesticides from different chemical classes adsorbed on Radiello® Tenax® passive tubes by thermal-desorption-GC/MS.

    Science.gov (United States)

    Raeppel, Caroline; Fabritius, Marie; Nief, Marie; Appenzeller, Brice M R; Briand, Olivier; Tuduri, Ludovic; Millet, Maurice

    2015-02-01

    An analytical methodology using automatic thermal desorption (ATD) and GC/MS was developed for the determination of 28 pesticides of different chemical classes (dichlobenil, carbofuran, trifluralin, clopyralid, carbaryl, flazasulfuron, mecoprop-P, dicamba, 2,4-MCPA, dichlorprop, 2,4-D, triclopyr, cyprodinil, bromoxynil, fluroxypyr, oxadiazon, myclobutanil, buprofezin, picloram, trinexapac-p-ethyl, ioxynil, diflufenican, tebuconazole, bifenthrin, isoxaben, alphacypermethrin, fenoxaprop and tau-fluvalinate) commonly used in nonagricultural areas in atmospheric samples. This methodology was developed to evaluate the indoor and outdoor atmospheric contamination by nonagricultural pesticides. Pesticides were sampled passive sampling tubes containing Tenax® adsorbent. Since most of these pesticides are polar (clopyralid, mecoprop-P, dicamba, 2,4-MCPA, dichlorprop, 2,4-D, triclopyr, bromoxynil, fluroxypyr, picloram, trinexapac-p-ethyl and ioxynil), a derivatisation step is required. For this purpose, a silylation step using N-(t-butyldimethylsilyl)-N-methyltrifluoroacetamide (MtBSTFA) was added before thermal desorption. This agent was chosen since it delivers very specific ions on electronic impact (m/z = M-57). This method was established with special consideration for optimal thermal desorption conditions (desorption temperature, desorb flow and duration; trap heating duration and flow; outlet split), linear ranges, limits of quantification and detection which varied from 0.005 to 10 ng and from 0.001 to 2.5 ng, respectively, for an uncertainty varied from 8 to 30 %. The method was applied in situ to the analysis of passive tubes exposed during herbicide application to an industrial site in east of France. PMID:25205153

  17. PEG/CaFe2O4 nanocomposite: Structural, morphological, magnetic and thermal analyses

    Science.gov (United States)

    Khanna, Lavanya; Verma, Narendra K.

    2013-10-01

    The coating of Polyethylene Glycol (PEG) on calcium ferrite (CaFe2O4) nanoparticles has been reported in the present study. The X-ray diffraction pattern revealed the formation of orthorhombic structure of bare CaFe2O4 nanoparticles, which was also retained after the PEG coating, along with additional characteristic peaks of PEG at 19° and 23°. The rings of CaFe2O4 nanoparticles were identified by the selected area electron diffraction pattern. The characteristic bands of PEG as observed in its Fourier transform infrared spectrum were also present in PEG coated CaFe2O4 nanoparticles, hence confirming its presence. In the thermal gravimetric studies, the complete thermal decomposition of PEG occurred in a one step process, but in case of PEG coated CaFe2O4 nanoparticles, the decomposition took place at a higher temperature owing to the formation of covalent bonds of PEG with CaFe2O4 nanoparticles. The presence of PEG on CaFe2O4 nanoparticles, spherical formation of PEG coated CaFe2O4 nanoparticles and reduced agglomeration in the CaFe2O4 nanoparticles were revealed by high resolution transmission electron microscope, transmission electron microscope and scanning electron microscope studies, respectively. In vibrating sample magnetometer analysis, both bare as well as coated CaFe2O4 nanoparticles exhibited superparamagnetic behavior. However, a drop in the magnetic saturation value was observed from 36.76 emu/g for CaFe2O4 nanoparticles to 6.74 emu/g for PEG coated CaFe2O4 nanoparticles, due to the formation of magnetically dead layer of PEG. In ZFC and FC analyses, superparamagnetic behavior with blocking temperature for bare and coated nanoparticles has been observed at ∼40 K and ∼60 K, respectively. The increase in the blocking temperature is attributed to the increase in the particle size after PEG coating.

  18. A Comparative Study: Dynamic and Thermal Behavior of Nanocrystalline and Powder Magnetic Materials in a Power Converter Application

    Science.gov (United States)

    Hilal, A.; Raulet, M. A.; Martin, C.; Sixdenier, F.

    2015-10-01

    In the design of such power electronics applications as power converters, lack of precise characterization and diagnosis of losses from components has unacceptable effects on efficiency, reliability, and power consumption. Because passive components, especially magnetic components, are crucially important in power converters, accurate characterization and modeling of magnetic materials is mandatory, to enable realistic prediction of their behavior under variable operating conditions. Temperature is one such condition that induces major changes in a component's behavior by modifying the material's magnetic properties. In the work discussed in this paper we investigated the magnetic and thermal behavior of nanocrystalline and powder materials in a DC-DC converter application. Core loss measurements under variable conditions were performed on toroid-shaped samples. Measured results were analyzed for different frequencies, flux densities, and temperatures.

  19. Magnetic field dependent thermal conductance in La0.67Ca0.33MnO3

    Science.gov (United States)

    Euler, C.; Hołuj, P.; Talkenberger, A.; Jakob, G.

    2015-05-01

    Using the differential 3 ω technique we measured the low-temperature out-of-plane thermal conductance of heteroepitaxial thin film La0.67Ca0.33MnO3 (LCMO). The magnetic field dependence of the thermal conductance reached values of up to 23%. The effect was observed to be largest in the vicinity of the metal-insulator transition, since the enhancement in thermal conductance is triggered by the colossal magnetoresistance effect increasing the electronic contribution to the thermal conductance. The point of the maximal change was adjusted by post-annealing the samples in an oxygen atmosphere. Samples with a higher transition temperature and lower epitaxial strain displayed a lower magnetic field dependence of up to 8% of the zero-field value. While the samples with a low strain state seemingly obeyed the Wiedemann-Franz law, those under high strain did not. Raman spectroscopy was applied to explain this discrepancy by an enhanced phononic density of states caused by rotational distortions of the unit cell. Our results show that in systems with strong electron-lattice interaction manipulation of the phonon spectrum is possible by magnetic fields.

  20. Numerical analysis of magnetic field effects on hydro-thermal behavior of a magnetic nanofluid in a double pipe heat exchanger

    Science.gov (United States)

    Shakiba, Ali; Vahedi, Khodadad

    2016-03-01

    This study attempts to numerically investigate the hydro-thermal characteristics of a ferrofluid (water and 4 vol% Fe3O4) in a counter-current horizontal double pipe heat exchanger, which is exposed to a non-uniform transverse magnetic field with different intensities. The magnetic field is generated by an electric current going through a wire located parallel to the inner tube and between two pipes. The single phase model and the control volume technique have been used to study the flow. The effects of magnetic field have been added to momentum equation by applying C++ codes in Ansys Fluent 14. The results show that applying this kind of magnetic field causes kelvin force to be produced perpendicular to the ferrofluid flow, changing axial velocity profile and creating a pair of vortices which leads to an increase in Nusselt number, friction factor and pressure drop. Comparing the enhancement percentage of Nusselt number, friction factor and pressure drop demonstrates that the optimum value of magnetic number for Reff=50 is between Mn=1.33×106 and Mn=2.37×106. So applying non-uniform transverse magnetic field can control the flow of ferrofluid and improve heat transfer process of double pipe heat exchanger.

  1. The airborne laser

    Science.gov (United States)

    Lamberson, Steven; Schall, Harold; Shattuck, Paul

    2007-05-01

    The Airborne Laser (ABL) is an airborne, megawatt-class laser system with a state-of-the-art atmospheric compensation system to destroy enemy ballistic missiles at long ranges. This system will provide both deterrence and defense against the use of such weapons during conflicts. This paper provides an overview of the ABL weapon system including: the notional operational concept, the development approach and schedule, the overall aircraft configuration, the technologies being incorporated in the ABL, and the current program status.

  2. Thermal and flow considerations for the 80 K shield of the SSC magnet cryostats

    International Nuclear Information System (INIS)

    The nominal temperatures in the SSC cryostat range between 4.2 K in the superconducting magnet and 300 K on the cryostat outer wall. To minimize the 4 K heat load, a thermal shield cooled by liquid and vapor nitrogen flows at 84 K and one a 20 K cooled by helium flow are incorporated in the cryostat. Tubes attached to the shields serve as conduits for cryogens. The liquid nitrogen tube in the cryostat is used for cryostat refrigeration and also for liquid distribution around the SSC rings. The second nitrogen line is used to return the vapor to the helium refrigerators for further processing. The nominal GN2 flow from a 4.3-km long cryogenic string (4 sections) to the surface is 64 g/s. The total liquid nitrogen consumption of approximately 5000 g/s will be supplied at one, two or more locations on the surface. The total heat load of the 80 K shield is estimated as 3.2 W/m. About 50% is composed of infrared radiation and remaining 50% by heat conduction through supports, vacuum barriers and other thermal connections between the shield and the 300 K outer wall. The required LN2 flow rate depends on the distribution and circulation schemes. The LN2 temperature will in turn vary depending on the flow rate and on the recooling methods used. For example, with a massflow of 400 g/s of LN2 the temperature rises from 82 K to 86 K between two compact recoolers 1 km apart. This temperature is higher thin desired. The temperature can be reduced by increasing the flow rate of the liquid or by using the continuous recooling. This paper discusses some thermal problems caused by certain mechanical designs of the 80 K shielding the possible improvement by using continuous recooling. In the following, we present results of the 80 K shield temperature distribution analysis, the 20 K shield heat load augmentation resulting from the increased 80 K shield temperatures, the continuous nitrogen recooling scheme and some flow timing related analysis

  3. Thermal and flow considerations for the 80 K shield of the SSC magnet cryostats

    International Nuclear Information System (INIS)

    The nominal temperatures in the SSC magnets range between 4.2 K in the superconducting coils and 300 K on the cryostat outer wall. To minimize the 4 K heat load, one thermal shield cooled by liquid and vapor nitrogen flows at 84 K, and another cooled by helium flow at 20 K are incorporated in the cryostat. Tubes attached to the shields serve as conduits for the cryogens. The liquid nitrogen tube in the cryostat is used for shield refrigeration and also for liquid distribution around the SSC rings. The second nitrogen line is used to return the vapor to the helium refrigerators for helium precooling. The nominal LN2 flow from a 4.3 km long cryogenic string (4 sections) to the surface is 64 g/s. The total liquid nitrogen consumption of approximately 5000 g/s will be supplied at one, two or more locations on the surface. The total heat load of the 80 K shield is estimated as 3.2 W/m: about 50% is composed of infrared radiation; the remaining 50% is by heat conduction through supports, vacuum barriers and other thermal connections between the shield and the 300 K outer wall. The required LN2 flow rate depends on the distribution and circulation schemes. The LN2 temperature will in turn vary depending on the flow rate and on the recooling method used. For example, with a massflow of 400 g/s of LN2 the temperature rises from 82 K to 86 K between two compact recoolers 1 km apart. This temperature is higher than desired. The temperature can be reduced by increasing the flow rate of the liquid or by using the continuous recooling scheme. This paper discusses some thermal problems caused by certain mechanical designs of the 80 K shield and the possible improvement by using continuous recooling. The authors present results of the 80 K shield temperature distribution analysis, the 20 K shield heat load augmentation resulting from the increased 80 K shield temperatures, the continuous nitrogen recooling scheme and some flow timing related analysis

  4. Thermal effects on paediatric patients undergoing magnetic resonance imaging in Greater Accra Region, Ghana

    International Nuclear Information System (INIS)

    Children have young thermoregulation mechanisms and more prominent to core body temperature making them tender to radiofrequency (RF) heating effect. With the increasing number of paediatric patients undergoing magnetic resonance imaging (MRI), dosimetric assessment from RF coil is necessary. The objective of the study was to determine the thermal effect of electromagnetic fields on children undergoing MRI examinations. The study modelled Penne's classical bio-heat equation to predict whole body RF dose using Finite Difference Time Domain approach. Temperature measurements and other data were performed on sixty-four paediatric patients undergoing MRI with a magnetic field strength of 0.3 T and l.5 T at 37 Military Hospital, Korle-Bu Teaching Hospital and Diagnostic Centre Limited. Similar measurements were taken using tissue equivalent phantom. Statistical analyses were done using SPSS. The maximum and minimum scan durations were 46 and 15 minutes with temperatures of 37°C and 36.2°C respectively. The temperature values recorded for the paediatrics were between 36°C to 38°C . Out of sixty-four patients investigated, 69%, 21 % and 5% of the patients' temperatures change was in the ranges of 0.1°C to 0.5°C , 0.6°C, to 0.9°C and l.0°C to l.5°C respectively. 5% of the patients from the study did not have any change in temperature. The values obtained from this study were well below the recommended guidance levels set by the International Electrotechnical Commission (lEC) and United State Food and Drug Administration (USFDA). From this study it was concluded that heating occurs during routine MRI procedures and can exceed 1°C per hour in some cases. Therefore, it is recommended that periodic monitoring of paediatric patients' temperatures should be the most paramount during magnetic resonance scan, particularly if the scan durations are prolonged. (au)

  5. Hot accretion disks with pairs: Effects of magnetic field and thermal cyclocsynchrotron radiation

    Science.gov (United States)

    Kusunose, Masaaki; Zdziarski, Andrzej A.

    1994-01-01

    We show the effects of thermal cyclosynchrotron radiation and magnetic viscosity on the structure of hot, two-temperature accretion disks. Magnetic field, B, is assumed to be randomly oriented and the ratio of magnetic pressure to either gas pressure, alpha = P(sub mag)/P(sub gas), or the sum of the gas and radiation pressures, alpha = (P(sub mag)/P(sub gas) + P(sub rad)), is fixed. We find those effects do not change the qualitative properties of the disks, i.e., there are still two critical accretion rates related to production of e(sup +/-) pairs, (M dot)((sup U)(sub cr)) and (M dot)((sup L)(sub cr)), that affect the number of local and global disk solutions, as recently found by Bjoernsson and Svensson for the case with B = 0. However, a critical value of the alpha-viscosity parameter above which those critical accretion rates disappear becomes smaller than alpha(sub cr) = 1 found in the case of B = 0, for P(sub mag) = alpha(P(sub gas) + P(sub rad)). If P(sub mag) = alpha P(sub gas), on the other hand, alpha(sub cr) is still about unity. Moreover, when Comptonized cyclosynchrotron radiation dominates Comptonized bremsstrahlung, radiation from the disk obeys a power law with the energy spectral index of approximately 0.5, in a qualitative agreement with X-ray observations of active galactic nuclei (AGNS) and Galactic black hole candidates. We also extend the hot disk solutions for P(sub mag) = alpha(P(sub gas) + P(sub rad)) to the effectively optically thick region, where they merge with the standard cold disk solutions. We find that the mapping method by Bjoernsson and Svensson gives a good approximation to the disk structure in the hot region and show where it breaks in the transition region. Finally, we find a region in the disk parameter space with no solutions due to the inability of Coulomb heating to supply enough energy to electrons.

  6. Magnetic field control of near-field radiative heat transfer and the realization of highly tunable hyperbolic thermal emitters

    Science.gov (United States)

    Moncada-Villa, E.; Fernández-Hurtado, V.; García-Vidal, F. J.; García-Martín, A.; Cuevas, J. C.

    2015-09-01

    We present a comprehensive theoretical study of the magnetic field dependence of the near-field radiative heat transfer (NFRHT) between two parallel plates. We show that when the plates are made of doped semiconductors, the near-field thermal radiation can be severely affected by the application of a static magnetic field. We find that irrespective of its direction, the presence of a magnetic field reduces the radiative heat conductance, and dramatic reductions up to 700% can be found with fields of about 6 T at room temperature. We show that this striking behavior is due to the fact that the magnetic field radically changes the nature of the NFRHT. The field not only affects the electromagnetic surface waves (both plasmons and phonon polaritons) that normally dominate the near-field radiation in doped semiconductors, but it also induces hyperbolic modes that progressively dominate the heat transfer as the field increases. In particular, we show that when the field is perpendicular to the plates, the semiconductors become ideal hyperbolic near-field emitters. More importantly, by changing the magnetic field, the system can be continuously tuned from a situation where the surface waves dominate the heat transfer to a situation where hyperbolic modes completely govern the near-field thermal radiation. We show that this high tunability can be achieved with accessible magnetic fields and very common materials like n -doped InSb or Si. Our study paves the way for an active control of NFRHT and it opens the possibility to study unique hyperbolic thermal emitters without the need to resort to complicated metamaterials.

  7. Magnetically softened iron oxide (MSIO) nanofluid and its application to thermally-induced heat shock proteins for ocular neuroprotection.

    Science.gov (United States)

    Bae, Seongtae; Jeoung, Jin Wook; Jeun, Minhong; Jang, Jung-Tak; Park, Joo Hyun; Kim, Yu Jeong; Lee, Kwan; Kim, Minkyu; Lee, Jooyoung; Hwang, Hey Min; Paek, Sun Ha; Park, Ki Ho

    2016-09-01

    Magnetically softened iron oxide (MSIO) nanofluid, PEGylated (Mn0.5Zn0.5)Fe2O4, was successfully developed for local induction of heat shock proteins (HSPs) 72 in retinal ganglion cells (RGCs) for ocular neuroprotection. The MSIO nanofluid showed significantly enhanced alternating current (AC) magnetic heat induction characteristics including exceptionally high SLP (Specific Loss Power, > 2000 W/g). This phenomenon was resulted from the dramatically improved AC magnetic softness of MSIO caused by the magnetically tailored Mn(2+) and Zn(2+) distributions in Fe3O4. In addition, the MSIO nanofluid with ultra-thin surface coating layer thickness and high monodispersity allowed for a higher cellular uptake up to a 52.5% with RGCs and enhancing "relaxation power" for higher AC heating capability. The RGCs cultured with MSIO nanofluid successfully induced HSPs 72 by magnetic nanofluid hyperthermia (MNFH). Moreover, it was interestingly observed that systematic control of "AC magnetically-induced heating up rate" reaching to a constant heating temperature of HSPs 72 induction allowed to achieve maximized induction efficiency at the slowest AC heating up rate during MNFH. In addition to in-vitro experimental verification, the studies of MSIO infusion behavior using animal models and a newly designed magnetic coil system demonstrated that the MSIO has promising biotechnical feasibility for thermally-induced HSPs agents in future glaucoma clinics. PMID:27294536

  8. MAGNET

    CERN Multimedia

    Benoit Curé

    2010-01-01

    The magnet worked very well at 3.8 T as expected, despite a technical issue that manifested twice in the cryogenics since June. All the other magnet sub-systems worked without flaw. The issue in the cryogenics was with the cold box: it could be observed that the cold box was getting progressively blocked, due to some residual humidity and air accumulating in the first thermal exchanger and in the adsorber at 65 K. This was later confirmed by the analysis during the regeneration phases. An increase in the temperature difference between the helium inlet and outlet across the heat exchanger and a pressure drop increase on the filter of the adsorber were observed. The consequence was a reduction of the helium flow, first compensated by the automatic opening of the regulation valves. But once they were fully opened, the flow and refrigeration power reduced as a consequence. In such a situation, the liquid helium level in the helium Dewar decreased, eventually causing a ramp down of the magnet current and a field...

  9. New option for solving the climatic problems with non-thermal laser driven boron fusion and ultrahigh magnetic fields

    OpenAIRE

    Hora, Heinrich

    2014-01-01

    In contrast to the broad stream of sustainable developments on fusion energy, new aspects are developed now by applying ultra-short, ultra-powerful laser pulses in a plasma-block ignition scheme by avoiding the well known difficulties of thermal-pressure instabilities and losses through using electro-dynamic non-thermal energy conversion. A further advantage is given by the new 10 kilo-Tesla magnetic fields for fusion of uncompressed proton-boron fuel which avoids problems of dangerous nuclea...

  10. New option for solving the climatic problems with non-thermal laser driven boron fusion and ultrahigh magnetic fields

    CERN Document Server

    Hora, Heinrich

    2014-01-01

    In contrast to the broad stream of sustainable developments on fusion energy, new aspects are developed now by applying ultra-short, ultra-powerful laser pulses in a plasma-block ignition scheme by avoiding the well known difficulties of thermal-pressure instabilities and losses through using electro-dynamic non-thermal energy conversion. A further advantage is given by the new 10 kilo-Tesla magnetic fields for fusion of uncompressed proton-boron fuel which avoids problems of dangerous nuclear radiation.

  11. Feeble magnetic fields generated by thermal charge fluctuations in extended metallic conductors: Implications for electric-dipole moment experiments

    International Nuclear Information System (INIS)

    A simple formulation for calculating the magnetic field external to an extended nonpermeable conducting body due to thermal current fluctuations within the body is developed, and is applied to a recent experimental search for the atomic electric-dipole moment (EDM) of 199Hg. It is shown that the thermal fluctuation field is only slightly smaller in magnitude than other noise sources in that experiment. The formulation is extended to permeable bodies, and the implications for general EDM experiments are discussed. copyright 1999 The American Physical Society

  12. Magnetization, crystal structure and anisotropic thermal expansion of single-crystal SrEr2O4

    OpenAIRE

    Li, Hai-Feng; Wildes, Andrew; Hou, Binyang; Zhang, Cong; Schmitz, Berthold; Meuffels, Paul; Roth, Georg; Brückel, Thomas

    2014-01-01

    The magnetization, crystal structure, and thermal expansion of a nearly stoichiometric Sr$_{1.04(3)}$Er$_{2.09(6)}$O$_{4.00(1)}$ single crystal have been studied by PPMS measurements and in-house and high-resolution synchrotron X-ray powder diffraction. No evidence was detected for any structural phase transitions even up to 500 K. The average thermal expansions of lattice constants and unit-cell volume are consistent with the first-order Gr\\"uneisen approximations taking into account only th...

  13. Tunnel magnetoresistance in thermally robust Mo/CoFeB/MgO tunnel junction with perpendicular magnetic anisotropy

    Directory of Open Access Journals (Sweden)

    B. Fang

    2015-06-01

    Full Text Available We report on tunnel magnetoresistance and electric-field effect in the Mo buffered and capped CoFeB/MgO magnetic tunnel junctions (MTJs with perpendicular magnetic anisotropy. A large tunnel magnetoresistance of 120% is achieved. Furthermore, this structure shows greatly improved thermal stability and stronger electric-field-induced modulation effect in comparison with the Ta/CoFeB/MgO-based MTJs. These results suggest that the Mo-based MTJs are more desirable for next generation spintronic devices.

  14. Thermal Entanglement in Two-Qutrit Heisenberg XX Chain with Different Dzyaloshinskii—Moriya Interaction and Nonuniform Magnetic Field

    International Nuclear Information System (INIS)

    The effects of the different Dzyaloshinskii—Moriya (DM) interaction on thermal entanglement of a two-qutrit Heisenberg XX spin chain in a nonuniform magnetic field are investigated. Our results imply that the x-component DM interaction plays a central role in enhancing quantum entanglement and it has a higher critical temperature than the z-component DM interaction. The entanglement can be tunable controlled by changing the multiple of the magnetic fields B1 and B2. Also we found that different DM interaction are competitive to each other in some conditions.

  15. Structural Analysis of Thermal Shields During a Quench of a Torus Magnet for the 12 GeV Upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Pastor, Orlando [JLAB; Willard, Thomas [NSC Technologies; Ghoshal, Probir K. [JLAB; Kashy, David H. [JLAB; Wiseman, Mark A. [JLAB; Kashikhin, V. [FNAL; Young, Glenn R. [JLAB; Elouadrhiri, Latifa [JLAB; Rode, Claus H. [JLAB

    2015-06-01

    A toroidal magnet system consisting of six superconducting coils is being built for the Jefferson Lab 12- GeV accelerator upgrade project. This paper details the analysis of eddy current effects during a quench event on the aluminum thermal shield. The shield has been analyzed for mechanical stresses induced as a result of a coil quench as well as a fast discharge of the complete magnet system. The shield has been designed to reduce the eddy current effects and result in stresses within allowable limits.

  16. Transient thermal and viscous irreversibilities through a poiseuille-benard channel in presence of a magnetic field

    International Nuclear Information System (INIS)

    The influence of an external magnetic field on transient thermal and viscous irreversibilities in Poiseuille-Benard channel for the laminar flow of an incompressible electrically conducting fluid is numerically investigated by solving the mass, momentum and energy conservation equations. Numerical simulation was performed for Reynolds number (Re) equal to 10 and an irreversibility distribution ratio φ equal to 0.1. The Stuart number (N) that describes the magnetic field effect, ranges between 0 and 10. Rayleigh and Prandtl numbers are fixed respectively at 104 and 0.71

  17. Synthesis and structural, magnetic, thermal, and transport properties of several transition metal oxides and aresnides

    Energy Technology Data Exchange (ETDEWEB)

    Das, Supriyo [Iowa State Univ., Ames, IA (United States)

    2010-01-01

    Oxide compounds containing the transition metal vanadium (V) have attracted a lot of attention in the field of condensed matter physics owing to their exhibition of interesting properties including metal-insulator transitons, structural transitions, ferromagnetic and an- tiferromagnetic orderings, and heavy fermion behavior. Binary vanadium oxides VnO2n-1 where 2 ≤ n ≤ 9 have triclinic structures and exhibit metal-insulator and antiferromagnetic transitions.[1–6] The only exception is V7O13 which remains metallic down to 4 K.[7] The ternary vanadium oxide LiV2O4 has the normal spinel structure, is metallic, does not un- dergo magnetic ordering and exhibits heavy fermion behavior below 10 K.[8] CaV2O4 has an orthorhombic structure[9, 10] with the vanadium spins forming zigzag chains and has been suggested to be a model system to study the gapless chiral phase.[11, 12] These provide great motivation for further investigation of some known vanadium compounds as well as to ex- plore new vanadium compounds in search of new physics. This thesis consists, in part, of experimental studies involving sample preparation and magnetic, transport, thermal, and x- ray measurements on some strongly correlated eletron systems containing the transition metal vanadium. The compounds studied are LiV2O4, YV4O8, and YbV4O8. The recent discovery of superconductivity in RFeAsO1-xFx (R = La, Ce, Pr, Gd, Tb, Dy, Sm, and Nd), and AFe2As2 (A = Ba, Sr, Ca, and Eu) doped with K, Na, or Cs at the A site with relatively high Tc has sparked tremendous activities in the condensed matter physics community and a renewed interest in the area of superconductivity as occurred following the discovery of the layered cuprate high Tc superconductors in 1986. To discover more supercon- ductors

  18. Temperature monitoring along the Rhine River based on airborne thermal infrared remote sensing: qualitative results compared to satellite data and validation with in situ measurements

    Science.gov (United States)

    Fricke, Katharina; Baschek, Björn

    2014-10-01

    Water temperature is an important parameter of water quality and influences other physical and chemical parameters. It also directly influences the survival and growth of animal and plant species in river ecosystems. In situ measurements do not allow for a total spatial coverage of water bodies and rivers that is necessary for monitoring and research at the Federal Institute of Hydrology (BfG), Germany. Hence, the ability of different remote sensing products to identify and investigate water inflows and water temperatures in Federal waterways is evaluated within the research project 'Remote sensing of water surface temperature'. The research area for a case study is the Upper and Middle Rhine River from the barrage in Iffezheim to Koblenz. Satellite products (e. g. Landsat and ASTER imagery) can only be used for rivers at least twice as wide as the spatial resolution of the satellite images. They can help to identify different water bodies only at tributaries with larger inflow volume (Main and Mosel) or larger temperature differences between the inflow (e. g. from power plants working with high capacity) and the river water. To identify and investigate also smaller water inflows and temperature differences, thermal data with better ground and thermal resolution is required. An aerial survey of the research area was conducted in late October 2013. Data of the surface was acquired with two camera systems, a digital camera with R, G, B, and Near-IR channels, and a thermal imaging camera measuring the brightness temperature in the 8-12 m wavelength region (TIR). The resolution of the TIR camera allowed for a ground resolution of 4 m, covering the whole width of the main stream and larger branches. The RGB and NIR data allowed to eliminate land surface temperatures from the analysis and to identify clouds and shadows present during the data acquisition. By degrading the spatial resolution and adding sensor noise, artificial Landsat ETM+ and TIRS datasets were created

  19. Geophex Airborne Unmanned Survey System

    International Nuclear Information System (INIS)

    Ground-based surveys place personnel at risk due to the proximity of buried unexploded ordnance (UXO) items or by exposure to radioactive materials and hazardous chemicals. The purpose of this effort is to design, construct, and evaluate a portable, remotely-piloted, airborne, geophysical survey system. This non-intrusive system will provide stand-off capability to conduct surveys and detect buried objects, structures, and conditions of interest at hazardous locations. During a survey, the operators remain remote from, but within visual distance of, the site. The sensor system never contacts the Earth, but can be positioned near the ground so that weak geophysical anomalies can be detected. The Geophex Airborne Unmanned Survey System (GAUSS) is designed to detect and locate small-scale anomalies at hazardous sites using magnetic and electromagnetic survey techniques. The system consists of a remotely-piloted, radio-controlled, model helicopter (RCH) with flight computer, light-weight geophysical sensors, an electronic positioning system, a data telemetry system, and a computer base-station. The report describes GAUSS and its test results

  20. Unconventional effects in the magnetization and magnetoconductivity of iron based superconductors near Tc as probed by thermal fluctuation spectroscopy

    OpenAIRE

    Ramos Álvarez, Alberto

    2016-01-01

    The main objective of this thesis was to study unconventional effects on the magnetization and Magnetoconductivity of iron-based superconductors, FeSCs, mainly family '122'. This was done through the so-called superconducting fluctuation spectroscopy above the superconducting critical temperature, Tc. This technique has been used in a considerable number of work to characterize the properties of superconductors (see for example). Moreover, the nature of the thermal fluctuations is determined,...

  1. Modeling the Magnetic and Thermal Structure of Active Regions: 1st Year 1st Semi-Annual Progress Report

    Science.gov (United States)

    Mikic, Zoran

    2003-01-01

    This report covers technical progress during the first six months of the first year of NASA SR&T contract "Modeling the Magnetic and Thermal Structure of Active Regions", NASW-03008, between NASA and Science Applications International Corporation, and covers the period January 14, 2003 to July 13, 2003. Under this contract SAIC has conducted research into theoretical modeling of the properties of active regions using the MHD model.

  2. Magnetic response of gelatin ferrogels across the sol-gel transition: the influence of high energy crosslinking on thermal stability.

    Science.gov (United States)

    Wisotzki, Emilia I; Eberbeck, Dietmar; Kratz, Harald; Mayr, Stefan G

    2016-05-01

    As emerging responsive materials, ferrogels have demonstrated significant potential for applications in areas of engineering to regenerative medicine. Promising techniques to study the behavior of magnetic nanoparticles (MNPs) in such matrices include magnetic particle spectroscopy (MPS) and magnetorelaxometry (MRX). This work investigated the magnetic response of gelatin-based ferrogels with increasing temperatures, before and after high energy crosslinking. The particle response was characterized by the nonlinear magnetization using MPS and quasistatic magnetization measurements as well as MRX to discriminate between Néel and Brownian relaxation mechanisms. The effective magnetic response of MNPs in gelatin was suppressed, indicating that the magnetization of the ferrogels was strongly influenced by competing dipole-dipole interactions. Significant changes in the magnetic behavior were observed across the gelatin sol-gel transition, as influenced by the matrix viscosity. These relaxation processes were modeled by Fourier transformation of the Langevin function, combined with a Debye term for the nonlinear magnetic response, for single core MNPs embedded in matrices of changing viscosities. Using high energy electron irradiation as a crosslinking method, modified ferrogels exhibited thermal stability on a range of timescales. However, MRX relaxation times revealed a slight softening around the gelatin sol-gel transition felt by the smallest particles, demonstrating a high sensitivity to observe local changes in the viscoelasticity. Overall, MPS and MRX functioned as non-contact methods to observe changes in the nanorheology around the native sol-gel transition and in crosslinked ferrogels, as well as provided an understanding of how MNPs were integrated into and influenced by the surrounding matrix. PMID:27029437

  3. Structural stability of hydrogenated amorphous carbon overcoats used in heat-assisted magnetic recording investigated by rapid thermal annealing

    KAUST Repository

    Wang, N.

    2013-01-01

    Ultrathin amorphous carbon (a-C) films are extensively used as protective overcoats of magnetic recording media. Increasing demands for even higher storage densities have necessitated the development of new storage technologies, such as heat-assisted magnetic recording (HAMR), which uses laser-assisted heating to record data on high-stability media that can store single bits in extremely small areas (∼1 Tbit/in.2). Because HAMR relies on locally changing the coercivity of the magnetic medium by raising the temperature above the Curie temperature for data to be stored by the magnetic write field, it raises a concern about the structural stability of the ultrathin a-C film. In this study, rapid thermal annealing (RTA) experiments were performed to examine the thermal stability of ultrathin hydrogenated amorphous carbon (a-C:H) films deposited by plasma-enhanced chemical vapor deposition. Structural changes in the a-C:H films caused by RTA were investigated by x-ray photoelectron spectroscopy, Raman spectroscopy, x-ray reflectivity, and conductive atomic force microscopy. The results show that the films exhibit thermal stability up to a maximum temperature in the range of 400-450 °C. Heating above this critical temperature leads to hydrogen depletion and sp 2 clustering. The critical temperature determined by the results of this study represents an upper bound of the temperature rise due to laser heating in HAMR hard-disk drives and the Curie temperature of magnetic materials used in HAMR hard disks. © 2013 American Institute of Physics.

  4. Effect of magnetic and thermal properties of iron oxide nanoparticles (IONs) in nitrile butadiene rubber (NBR) latex

    Energy Technology Data Exchange (ETDEWEB)

    Ong, Hun Tiar; Julkapli, Nurhidayatullaili Muhd; Hamid, Sharifah Bee Abd, E-mail: sharifahbee@um.edu.my; Boondamnoen, O.; Tai, Mun Foong

    2015-12-01

    Nitrile butadiene rubber (NBR) gloves are one of the most important personal protective equipments but they are possible to tear off and contaminate food or pharmaceutical and healthcare products during manufacturing and packaging process. High tendency of torn glove remaining in food or products due to white or light flesh-coloured glove is not easy to be detected by naked eyes. In this paper, iron oxide nanoparticles (IONs) selected as additive for NBR to improve its detectability by mean of magnetic properties. IONs synthesized via precipitation method and compounded with NBR latex before casting on petri dish. The properties of IONs were investigated by X-ray Diffractometry (XRD), Transmission Electron Microscope (TEM), Raman Spectroscopy and Vibrating Sample Magnetometer (VSM). Meanwhile NBR/IONs composites were studied by Thermogravimetry Analysis (TGA), Differential Scanning Calorimetry (DSC) and Vibrating Sample Magnetometer (VSM). It observed that, synthesized IONs shows of 25.28 nm crystallite with 25.86 nm semipherical (changed as) shape. Meanwhile, Magnetite and maghemite phase are found in range of 670 cm{sup −1} and 700 cm{sup −1} respectively, which it contributes magnetization saturation of 73.96 emu/g at 10,000 G by VSM. Thermal stability and magnetic properties were increased with incorporating IONs into NBR latex up to 20 phr. NBR/IONs 5 phr has the optimum thermal stability, lowest glass transition temperature (−14.83 °C) and acceptable range of magnetization saturation (3.83 emu/g at 10,000 G) to form NBR gloves with magnetic detectability. - Highlights: • We synthesized IONs with high magnetization saturation (M{sub s}). • High M{sub s} of IONs were incorporated into NBR latex in order to induce magnetic properties in the NBR composite. • Introduction of IONs into NBR latex would improve thermal properties. • The produced NBR/IONs 5 phr composite exceeded the minimum magnetic moment sensor of the detector. • They have high

  5. The effect of non-thermal electrons on obliquely propagating electron acoustic waves in a magnetized plasma

    Science.gov (United States)

    Singh, Satyavir; Bharuthram, Ramashwar

    2016-07-01

    Small amplitude electron acoustic solitary waves are studied in a magnetized plasma consisting of hot electrons following Cairn's type non-thermal distribution function and fluid cool electrons, cool ions and an electron beam. Using reductive perturbation technique, the Korteweg-de-Vries-Zakharov-Kuznetsov (KdV-ZK) equation is derived to describe the nonlinear evolution of electron acoustic waves. It is observed that the presence of non-thermal electrons plays an important role in determining the existence region of solitary wave structures. Theoretical results of this work is used to model the electrostatic solitary structures observed by Viking satellite. Detailed investigation of physical parameters such as non-thermality of hot electrons, beam electron velocity and temperature, obliquity on the existence regime of solitons will be discussed.

  6. Thermal, radioactive and magnetic properties of the lavas of the Mt Melbourne Volcanic Field (Victoria Land, Antarctica

    Directory of Open Access Journals (Sweden)

    Egidio Armadillo

    2009-06-01

    Full Text Available We present the results of measurements of physical properties carried out on mafic lavas from the Mt Melbourne
    Volcanic Field, useful for interpretation of geophysical surveys designed to shed light on the structure of the
    crust. The thermal conductivity is comparable to that of glass and shows a clear negative dependence on porosity.
    The volume heat capacity and the thermal diffusivity are less variable. The concentration of the thermally
    important natural radioactive isotopes was determined by gamma-ray spectrometry. Lavas denoted a rather low
    heat-production rate, and the largest concentration of heat-producing elements (potassium, uranium, thorium
    was found in the trachyte samples. The magnetic susceptibility is more variable than the other physical properties
    and, among the several iron-titanium oxides, it appears primarily controlled by the ulvöspinel-magnetite solid
    solution series.

  7. Structural and magnetic effects on thermal emittance of La1−xSrxMnO3 from the first principles calculation

    International Nuclear Information System (INIS)

    Generalized gradient approximation (GGA) exchange-correlation functional was used in the first-principles method to calculate thermal emittance of La1−xSrxMnO3 (LSMO). The effects of structure and magnetism on thermal emittance of LSMO were systematically investigated by the complex dielectric function. It is found that the LSMO with orthorhombic structure has a higher thermal emittance than that with rhombohedral structure at the same temperature. When the magnetism varying with temperature of LSMO is put into consideration, the magnetic different make a significant change on thermal emittance and the variation of thermal emittance of La0.75Sr0.25MnO3 is the biggest among x=0, 0.2, 0.25, 0.5. It is found that thermal emittance have a low value at the low temperature and have a high value at the high temperature, due to the unique feature of variable thermal emittance based on metal-insulator transition, which makes LSMO attractive as potential thermal control materials. - Highlights: • The emittance of La1-xSrxMnO3 (LSMO) varies with different magnetism state. • Orthorhombic LSMO has larger emittance than rhombohedral LSMO at same temperature. • If the magnetism varying with temperature of LSMO is considered, the variation of emittance of La0.75Sr0.25MnO3 is the biggest among x=0, 0.2, 0.25 and 0.5

  8. Magnetic fields, non-thermal radiation and particle acceleration in colliding winds of WR-O stars

    CERN Document Server

    Falceta-Goncalves, D

    2015-01-01

    Non-thermal emission has been detected in WR-stars for many years at long wavelengths spectral range, in general attributed to synchrotron emission. Two key ingredients are needed to explain such emissions, namely magnetic fields and relativistic particles. Particles can be accelerated to relativistic speeds by Fermi processes at strong shocks. Therefore, strong synchrotron emission is usually attributed to WR binarity. The magnetic field may also be amplified at shocks, however the actual picture of the magnetic field geometry, intensity, and its role on the acceleration of particles at WR binary systems is still unclear. In this work we discuss the recent developments in MHD modelling of wind-wind collision regions by means of numerical simulations, and the coupled particle acceleration processes related.

  9. Thermal stability of the induced magnetic anisotropy and structure of the nanocrystalline alloy FeCuNbSiB

    International Nuclear Information System (INIS)

    The magnetic anisotropy induced in the ribbons of the Fe73.5Cu1Nb3Si13.5B9 alloy in the course of stress annealing combined with the nanocrystallising one was investigated. Crystalline phases formed during the above treatments were studied by the Moessbauer method. Analysis of the Moessbauer results showed that the content of the Fe-Si phases depends neither on the exposure time nor on the value of the induced magnetic anisotropy constant. At the same time, in the regions containing, along with Fe, Nb and B the process of redistributing the elements proceeds with time, and the deeper the process, the higher the thermal stability of the induced magnetic anisotropy

  10. Thermal and magnetic behavior of Angustifolia Kunth bamboo fibers covered with Fe{sub 3}O{sub 4} particles

    Energy Technology Data Exchange (ETDEWEB)

    Calvo, S. [Laboratorio de Magnetismo y Materiales Avanzados, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Sede Manizales, Manizales (Colombia); Arias, N.P. [Laboratorio de Materiales Nanoestructurados y Funcionales, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Sede Manizales, Manizales (Colombia); Departamento de Ingenieria Electrica, Electronica y Computacion, Facultad de Ingenieria y Arquitectura, Universidad Nacional de Colombia, Sede Manizales, Manizales (Colombia); Giraldo, O., E-mail: ohggiraldo@hotmail.com [Laboratorio de Materiales Nanoestructurados y Funcionales, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Sede Manizales, Manizales (Colombia); Rosales-Rivera, A.; Moscoso, O. [Laboratorio de Magnetismo y Materiales Avanzados, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Sede Manizales, Manizales (Colombia)

    2012-08-15

    Several Angustifolia Kunth bamboo fibers, which have been previously treated with an alkaline solution, were coated with magnetite particles. The coating of the fibers was achieved by an in-situ co-precipitation method with Fe{sup 2+} and Fe{sup 3+}in NaOH or NH{sub 4}OH. The fibers were evaluated by chemical analysis using atomic absorption (A.A.) technique, structural characterization by X-ray diffraction (XRD), thermal stability with thermo-gravimetric analysis (TGA) in nitrogen at temperature range between 23 Degree-Sign C and 800 Degree-Sign C and magnetic behavior using vibrating sample magnetometry (VSM) applying a magnetic field between -27 KOe and 27 KOe at room temperature. We found that the thermal stability and magnetization depend of the synthesis method used to cover the Angustifolia Kunth bamboo fibers. In addition, an improved magnetic response was observed when NaOH solution is used to generate the magnetite coating on the fiber surface.

  11. Experimental validation of the thermal performance of the 1.9 K magnet cryostats during the commissioning of the LHC

    CERN Document Server

    Maglioni, C; Poncet, A

    2009-01-01

    The LHC machine, at present in the commissioning phase at CERN, is composed of eight 1.9 K superconducting magnet sectors independently operated. Assembled in 8 continuous segments of approximately 2.7 km length each, the HeII cryostats for the 1232 dipoles magnets and 438 Short Straight Sections (housing the quadrupole magnets) were designed to fulfil tight heat load budgets for an affordable large-scale project. The commissioning of the cryogenic system of the first LHC sectors is under way since January 2007 and 5 sectors have now been operated at their nominal temperatures of 1.9 K. An experimental assessment of the thermal performance of the final machine is therefore possible, allowing comparison with design estimates. After a brief description of the layout of the LHC cryostats, and their associated cryogenic and vacuum sectorisations, calorimetric measurements of the heat loads to the 1.9 K magnets and to the cryostat thermal shielding are presented and discussed.

  12. Silica/potassium ferrite nanocomposite: Structural, morphological, magnetic, thermal and in vitro cytotoxicity analysis

    International Nuclear Information System (INIS)

    Highlights: • Silica coating on potassium ferrite nanoparticles is reported. • Their structural, morphological, thermal behaviour is studied and compared. • Both bare and coated nanoparticles are superparamagnetic and biocompatible. -- Abstract: The coating of silica on potassium ferrite (KFeO2) nanoparticles has been reported in the present study. The X-ray diffraction pattern revealed the formation of orthorhombic structure of bare potassium ferrite nanoparticles, which was also retained after the silica coating, along with a broad band near 2θ ∼ 20–25° pertaining to the presence of amorphous silica. The size of bare and coated potassium ferrite nanoparticles was found to be 4–8 nm and 10–22 nm, respectively, as observed from transmission electron microscope. The presence of silica was also revealed by the Fourier transform infrared spectrum and high resolution transmission electron microscope. In vibrating sample magnetometer analysis, both bare as well as coated potassium ferrite nanoparticles exhibited superparamagnetic behaviour with magnetic saturation values, 49.01 and 21.17 emu/g, respectively. Dose-dependent cellular toxicity was observed in the in vitro MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, a tetrazole) – assay study on Jurkat cells, where both bare as well as silica coated nanoparticles exhibited non-toxicity below 250 μg/ml. An augmentation of cell viability was observed in case of silica coated potassium ferrite nanoparticles. The nanosize, superparamagnetic behaviour and enhanced cell viability make silica coated potassium ferrite nanoparticles a potential claimant for biomedical applications

  13. Silica/potassium ferrite nanocomposite: Structural, morphological, magnetic, thermal and in vitro cytotoxicity analysis

    Energy Technology Data Exchange (ETDEWEB)

    Khanna, Lavanya, E-mail: lavanshya@yahoo.co.in; Verma, N.K.

    2013-11-01

    Highlights: • Silica coating on potassium ferrite nanoparticles is reported. • Their structural, morphological, thermal behaviour is studied and compared. • Both bare and coated nanoparticles are superparamagnetic and biocompatible. -- Abstract: The coating of silica on potassium ferrite (KFeO{sub 2}) nanoparticles has been reported in the present study. The X-ray diffraction pattern revealed the formation of orthorhombic structure of bare potassium ferrite nanoparticles, which was also retained after the silica coating, along with a broad band near 2θ ∼ 20–25° pertaining to the presence of amorphous silica. The size of bare and coated potassium ferrite nanoparticles was found to be 4–8 nm and 10–22 nm, respectively, as observed from transmission electron microscope. The presence of silica was also revealed by the Fourier transform infrared spectrum and high resolution transmission electron microscope. In vibrating sample magnetometer analysis, both bare as well as coated potassium ferrite nanoparticles exhibited superparamagnetic behaviour with magnetic saturation values, 49.01 and 21.17 emu/g, respectively. Dose-dependent cellular toxicity was observed in the in vitro MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, a tetrazole) – assay study on Jurkat cells, where both bare as well as silica coated nanoparticles exhibited non-toxicity below 250 μg/ml. An augmentation of cell viability was observed in case of silica coated potassium ferrite nanoparticles. The nanosize, superparamagnetic behaviour and enhanced cell viability make silica coated potassium ferrite nanoparticles a potential claimant for biomedical applications.

  14. Simultaneous investigation of thermal, acoustic, and magnetic emission during martensitic transformation in single-crystalline Ni2MnGa

    Science.gov (United States)

    Tóth, László Z.; Daróczi, Lajos; Szabó, Sándor; Beke, Dezső L.

    2016-04-01

    Simultaneous thermal, acoustic, and magnetic emission (AE and ME) measurements during thermally induced martensitic transformation in Ni2MnGa single crystals demonstrate that all three types of the above noises display many coincident peaks and the same start and finish temperatures. The amplitude and energy distribution functions for AE and ME avalanches satisfy power-law behavior, corresponding to the symmetry of the martensite. At zero external magnetic field asymmetry in the exponents was obtained: their value was larger for heating than for cooling. Application of constant, external magnetic fields (up to B =722 mT) leads to the disappearance of the above asymmetry, due to the decrease of the multiplicity of the martensite variants. Time correlations (i.e., the existence of nonhomogeneous temporal processes) within AE as well as ME emission events are demonstrated by deviations from the uncorrelated behavior on probability distributions of waiting times as well as of a sequence of number of events. It is shown that the above functions collapse on universal master curves for cooling and heating as well as for AE and ME noises. The analysis of the existence of temporal correlations between AE and ME events revealed that at short times the acoustic signals show a time delay relative to the magnetic one, due to the time necessary for the propagation of the ultrasound. At intermediate times, as expected, the magnetic signal is delayed, i.e., the magnetic domain rearrangement followed the steps of structural transformation. At much longer times the deviation from an uncorrelated (Poisson-type) behavior is attributed to the nonhomogeneity of the avalanche statistics.

  15. Suppression of Parallel Transport in Turbulent Magnetized Plasmas and Its Impact on the Non-thermal and Thermal Aspects of Solar Flares

    Science.gov (United States)

    Bian, Nicolas H.; Kontar, Eduard P.; Emslie, A. Gordon

    2016-06-01

    The transport of the energy contained in electrons, both thermal and suprathermal, in solar flares plays a key role in our understanding of many aspects of the flare phenomenon, from the spatial distribution of hard X-ray emission to global energetics. Motivated by recent RHESSI observations that point to the existence of a mechanism that confines electrons to the coronal parts of flare loops more effectively than Coulomb collisions, we here consider the impact of pitch-angle scattering off turbulent magnetic fluctuations on the parallel transport of electrons in flaring coronal loops. It is shown that the presence of such a scattering mechanism in addition to Coulomb collisional scattering can significantly reduce the parallel thermal and electrical conductivities relative to their collisional values. We provide illustrative expressions for the resulting thermoelectric coefficients that relate the thermal flux and electrical current density to the temperature gradient and the applied electric field. We then evaluate the effect of these modified transport coefficients on the flare coronal temperature that can be attained, on the post-impulsive-phase cooling of heated coronal plasma, and on the importance of the beam-neutralizing return current on both ambient heating and the energy loss rate of accelerated electrons. We also discuss the possible ways in which anomalous transport processes have an impact on the required overall energy associated with accelerated electrons in solar flares.

  16. Analytical estimation of ultrasound properties, thermal diffusivity, and perfusion using magnetic resonance-guided focused ultrasound temperature data.

    Science.gov (United States)

    Dillon, C R; Borasi, G; Payne, A

    2016-01-21

    For thermal modeling to play a significant role in treatment planning, monitoring, and control of magnetic resonance-guided focused ultrasound (MRgFUS) thermal therapies, accurate knowledge of ultrasound and thermal properties is essential. This study develops a new analytical solution for the temperature change observed in MRgFUS which can be used with experimental MR temperature data to provide estimates of the ultrasound initial heating rate, Gaussian beam variance, tissue thermal diffusivity, and Pennes perfusion parameter. Simulations demonstrate that this technique provides accurate and robust property estimates that are independent of the beam size, thermal diffusivity, and perfusion levels in the presence of realistic MR noise. The technique is also demonstrated in vivo using MRgFUS heating data in rabbit back muscle. Errors in property estimates are kept less than 5% by applying a third order Taylor series approximation of the perfusion term and ensuring the ratio of the fitting time (the duration of experimental data utilized for optimization) to the perfusion time constant remains less than one. PMID:26741344

  17. Effect of magnetic and thermal properties of iron oxide nanoparticles (IONs) in nitrile butadiene rubber (NBR) latex

    Science.gov (United States)

    Ong, Hun Tiar; Julkapli, Nurhidayatullaili Muhd; Hamid, Sharifah Bee Abd; Boondamnoen, O.; Tai, Mun Foong

    2015-12-01

    Nitrile butadiene rubber (NBR) gloves are one of the most important personal protective equipments but they are possible to tear off and contaminate food or pharmaceutical and healthcare products during manufacturing and packaging process. High tendency of torn glove remaining in food or products due to white or light flesh-coloured glove is not easy to be detected by naked eyes. In this paper, iron oxide nanoparticles (IONs) selected as additive for NBR to improve its detectability by mean of magnetic properties. IONs synthesized via precipitation method and compounded with NBR latex before casting on petri dish. The properties of IONs were investigated by X-ray Diffractometry (XRD), Transmission Electron Microscope (TEM), Raman Spectroscopy and Vibrating Sample Magnetometer (VSM). Meanwhile NBR/IONs composites were studied by Thermogravimetry Analysis (TGA), Differential Scanning Calorimetry (DSC) and Vibrating Sample Magnetometer (VSM). It observed that, synthesized IONs shows of 25.28 nm crystallite with 25.86 nm semipherical (changed as) shape. Meanwhile, Magnetite and maghemite phase are found in range of 670 cm-1 and 700 cm-1 respectively, which it contributes magnetization saturation of 73.96 emu/g at 10,000 G by VSM. Thermal stability and magnetic properties were increased with incorporating IONs into NBR latex up to 20 phr. NBR/IONs 5 phr has the optimum thermal stability, lowest glass transition temperature (-14.83 °C) and acceptable range of magnetization saturation (3.83 emu/g at 10,000 G) to form NBR gloves with magnetic detectability.

  18. Non-thermal Gamma-Ray Emission from Delayed Pair Breakdown in a Magnetized and Photon-rich Outflow

    Science.gov (United States)

    Gill, Ramandeep; Thompson, Christopher

    2014-12-01

    We consider delayed, volumetric heating in a magnetized outflow that has broken out of a confining medium and expanded to a high Lorentz factor (Γ ~ 102-103) and low optical depth to scattering (τ T ~ 10-3-10-2). The energy flux at breakout is dominated by the magnetic field, with a modest contribution from quasi-thermal gamma rays whose spectrum was calculated in Paper I. We focus on the case of extreme baryon depletion in the magnetized material, but allow for a separate baryonic component that is entrained from a confining medium. Dissipation is driven by relativistic motion between these two components, which develops once the photon compactness drops below 4 × 103(Ye /0.5)-1. We first calculate the acceleration of the magnetized component following breakout, showing that embedded MHD turbulence provides significant inertia, the neglect of which leads to unrealistically high estimates of flow Lorentz factor. After reheating begins, the pair and photon distributions are evolved self-consistently using a one-zone kinetic code that incorporates an exact treatment of Compton scattering, pair production and annihilation, and Coulomb scattering. Heating leads to a surge in pair creation, and the scattering depth saturates at τ T ~ 1-4. The plasma maintains a very low ratio of particle to magnetic pressure, and can support strong anisotropy in the charged particle distribution, with cooling dominated by Compton scattering. High-energy power-law spectra with photon indices in the range observed in gamma-ray bursts (GRBs; -3 seed energy in quasi-thermal photons. We contrast our results with those for continuous heating across an expanding photosphere, and show that the latter model produces soft-to-hard evolution that is inconsistent with observations of GRBs.

  19. Vortex fluctuations, negative Hall effect, and thermally activated resistivity in layered and thin-film superconductors in an external magnetic field

    International Nuclear Information System (INIS)

    The thermally activated resistivity, rxx, and the negative Hall resistivity, rxy are explained as two consequences of the same effect, namely the unbinding of vortex pairs in the vicinity of Tc. Both rxx and rxy exhibit a thermally activated behaviour. The activation energy depends logarithmically on the magnetic field. Our explanation suggests rxy ∝ raxx with a = 1 in accordance with recent measurements

  20. Loading experiment and thermal analysis for conduction cooled magnet of SMES system

    Institute of Scientific and Technical Information of China (English)

    Gang WU; Huiling WANG; Jiangbo XIE; Yan ZHAO; Yuejin TANG; Jindong LI; Jing SHI

    2009-01-01

    China's first 35kJ high temperature superconducting magnetic energy storage (SMES) system with an experiment equipment was depicted. The dynamic heat analysis of the magnet of the SMES was conducted through the current load test on the directly cooled conduction magnet. The research results were as follows:when the converter charges and discharges the magnet for energy storage, the hysteresis loss is the main part of power loss, and contributes significantly to temperature rise;reducing the current frequency at the side of direct current is conducive to restraining temperature rise. The optimizing factors of the cool-guide structure were analyzed based on the heat stability theory, and it was found that the heat transfer of its key part (at the top of the magnet) must be strengthened to reduce the axial temperature difference of the magnet.

  1. A thermally stable heating mechanism for the intracluster medium: turbulence, magnetic fields and plasma instabilities

    OpenAIRE

    Kunz, M. W.; Schekochihin, A. A.; Cowley, S. C.; Binney, J. J.; Sanders, J. S.

    2010-01-01

    We consider the problem of self-regulated heating and cooling in galaxy clusters and the implications for cluster magnetic fields and turbulence. Viscous heating of a weakly collisional magnetised plasma is regulated by the pressure anisotropy with respect to the local direction of the magnetic field. The intracluster medium is a high-beta plasma, where pressure anisotropies caused by the turbulent stresses and the consequent local changes in the magnetic field will trigger very fast microsca...

  2. Study of thermal stability of permanent magnets by the method of Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    A method permitting identification of residual magnetization factor α, as applied to permanent magnets from barium ferrite BaFe12O19, is described. Formulas for indentification of factor α based on analysis of the Moessbauer spectra of 57Fe nuclei obtained in the temperature range of 120-300 K, where magnets from barium ferrite manifest special instability, are provided. The value of factor α obtained based on the Moessbauer spectra is 2 ·10-3 deg -1, which coincides with the value obtained based on magnetic measurements

  3. Thermal and structural performance of a single tube support post for the Superconducting Super Collider dipole magnet cryostat

    International Nuclear Information System (INIS)

    The reentrant support post currently incorporated in the Superconducting Super Collider (SSC) dipole cryostat has been shown to meet the structural and thermal requirements of the cryostat, both in prototype magnet assemblies and through component testing. However, the reentrant post design has two major drawbacks: tight dimensional control on all components, and cost driven by these tolerance constraints and a complex assembly procedure. A single tube support post has been developed as an alternative to the reentrant post design. Several prototype assemblies have been fabricated and subjected to structural testing. Compressive, tensile, and bending forces were applied to each assembly with deflection measured at several locations. A prototype support post has also been thermally evaluated in a heat leak measurement facility. Heat load to 4.2 K was measured with the intermediate post intercept operating at various temperatures while thermometers positioned along the conductive path of the post mapped thermal gradients. Results from these measurements indicate the single tube support post meets the design criteria for the SSC dipole magnet cryostat support system

  4. Thermally activated dissipation and upper critical magnetic field under the strong electrostatic field in the BiPbSrCaCuO thin film

    International Nuclear Information System (INIS)

    Three different regimes of thermally activated dissipation behaviour were determined in the superconducting (Bi,Pb)2Sr2Ca2Cu3OX thin film in dependence on the external magnetic field. The negative electrostatic field applied to the film surface has been found to increase the activation energy of flux creep in relatively low magnetic fields. The upper critical magnetic field determined from resistive measurements increases in the vicinity of superconducting transition temperature under the influence of the electrostatic field. (orig.)

  5. The influence of the solid thermal conductivity on active magnetic regenerators

    DEFF Research Database (Denmark)

    Nielsen, Kaspar Kirstein; Engelbrecht, Kurt

    2012-01-01

    range of thermal conductivities, operating frequencies, a long and short regenerator, and finally a regenerator with a low and a high number of transfer units (NTU) regenerator. In this way the performance is mapped out and the impact of the thermal conductivity of the solid is probed. Modeling shows...

  6. Modeling an unmitigated thermal quench event in a large field magnet in a DEMO reactor

    International Nuclear Information System (INIS)

    The superconducting magnet systems of future fusion reactors, such as a Demonstration Power Plant (DEMO), will produce magnetic field energies in the 10 s of GJ range. The release of this energy during a fault condition could produce arcs that can damage the magnets of these systems. The public safety consequences of such events must be explored for a DEMO reactor because the magnets are located near the DEMO's primary radioactive confinement barrier, the reactor's vacuum vessel (VV). Great care will be taken in the design of DEMO's magnet systems to detect and provide a rapid field energy dump to avoid any accidents conditions. During an event when a fault condition proceeds undetected, the potential of producing melting of the magnet exists. If molten material from the magnet impinges on the walls of the VV, these walls could fail, resulting in a pathway for release of radioactive material from the VV. A model is under development at Idaho National Laboratory (INL) called MAGARC to investigate the consequences of this accident in a large toroidal field (TF) coil. Recent improvements to this model are described in this paper, along with predictions for a DEMO relevant event in a toroidal field magnet

  7. Analysis of Multi-Component Natural Remanent Magnetization Based on the Thermal Demagnetisation Spectrum

    Czech Academy of Sciences Publication Activity Database

    Man, Otakar

    2003-01-01

    Roč. 47, č. 2 (2003), s. 359-370. ISSN 0039-3169 R&D Projects: GA ČR GA205/02/1576 Institutional research plan: CEZ:AV0Z3013912 Keywords : paleomagnetism and paleomagnetic stability * natural remanent magnetization * partial demagnetization Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 0.426, year: 2003

  8. Magnetic, transport, and thermal properties of ferromagnetic EuB6

    International Nuclear Information System (INIS)

    Magnetic measurements on Al-flux grown EuB6 crystals show that this material orders ferromagnetically with a transition temperature T/sub c/=13.7 K. The effective moment derived from paramagnetic susceptibility measurements gives μ/sub eff/=7.76 μ/sub B/, and the saturation magnetization extrapolated to 0 K is within 10% of the theoretical value of 7 μ/sub B/ expected for Eu+2. The magnetic order, however, cannot be that of a simple colinear ferromagnet because the magnetic specific heat in zero applied magnetic field shows a broad maximum centered about 9 K rather than the expected lambda-like anomaly at 13.7 K. Finally, transport measurements suggest that EuB6 is an intrinsic semimental

  9. Effect of thermal treatment on coercivity of SmCo/sub 5/ sintered magnets

    International Nuclear Information System (INIS)

    Permanent magnet materials composed of transition and rare earth metals exhibit high energy products. Samarium cobalt magnets are developed and research is done to have high coercivity. Chemistry is varied from 34 to 36 weight percent of samarium in Sm/sub 1/Co/sub 5/ compound. Effect of chemistry and sintering treatment temperatures on final properties has been studied. Magnets are manufactured by powder metallurgical technique involving isostatic pressing and sintering in C. Then the magnets are inert atmosphere at temperatures range of 1140-1170 deg. C. It subject to post sintering aging treatment in temperature range of 800-900 deg. C is observed that coercivity of Sm/sub 1/Co/sub 5/ magnet varies with aging temperature and can be improved by post sintering aging treatment. (author)

  10. Analysis of airborne particulate matter

    International Nuclear Information System (INIS)

    An airborne particulate matter (APM) consists of many kinds of solid and liquid particles in air. APM analysis methods and the application examples are explained on the basis of paper published after 1998. Books and general remarks, sampling and the measurement of concentration and particle distribution, elemental analysis methods and the present state of analysis of species are introduced. Tapered Element Oscillating Microbalance (TEOM) method can collect continuously the integrating mass, but indicates lower concentration. Cu, Ni, Zn, Co, Fe(2), Mn, Cd, Fe(3) and Pb, the water-soluble elements, are determined by ion-chromatography after ultrasonic extraction of the aqueous solution. The detection limit of them is from 10 to 15 ppb (30 ppb Cd and 60 ppb Pb). The elemental carbon (EC) and organic carbon (OC) are separated by the thermal mass measurement-differential scanning calorimeter by means of keeping at 430degC for 60 min. 11 research organizations compared the results of TC (Total Carbon) and EC by NIOSH method 5040 and the thermal method and obtained agreement of TC. ICP-MS has been developed in order to determine correctly and quickly the trace elements. The determination methods for distinction of chemical forms in the environment were developed. GC/MS, LC/MS and related technologies for determination of organic substances are advanced. Online real-time analysis of APN, an ideal method, is examined. (S.Y.)

  11. Attainable entanglement of unitary transformed thermal states in liquid-state nuclear magnetic resonance with the chemical shift

    CERN Document Server

    Ota, Y; Ohba, I; Yoshida, N; Mikami, Shuji; Ohba, Ichiro; Ota, Yukihiro; Yoshida, Noriyuki

    2006-01-01

    Recently, Yu, Brown, and Chuang [Phys. Rev. A {\\bf 71}, 032341 (2005)] investigated the entanglement attainable from unitary transformed thermal states in liquid-state nuclear magnetic resonance (NMR). Their research gave an insight into the role of the entanglement in a liquid-state NMR quantum computer. Moreover, they attempted to reveal the role of mixed-state entanglement in quantum computing. However, they assumed that the Zeeman energy of each nuclear spin which corresponds to a qubit takes a common value for all; there is no chemical shift. In this paper, we research a model with the chemical shifts and analytically derive the physical parameter region where unitary transformed thermal states are entangled, by the positive partial transposition (PPT) criterion with respect to any bipartition. We examine the effect of the chemical shifts on the boundary between the separability and the nonseparability, and find it is negligible.

  12. Influence of stoichiometry on phase constitution, thermal behavior and magnetic properties of Ba-hexaferrite particles prepared via SHS route

    International Nuclear Information System (INIS)

    Barium hexaferrite magnetic particles were synthesized via self-propagating high temperature synthesis (SHS) route by thermal initiation of compact mixed powders of iron, iron oxide and barium nitrate using various Fe(total)/Ba molar ratios of 9-12. As-SHS treated and post synthesis specimens were characterized by X-ray powder diffraction, VSM, DTA/TGA and SEM. DTA/TGA studies revealed that the formation temperature of barium hexaferrite decreased by increasing of Fe/Ba molar ratio. VSM measurement also indicated that saturation magnetization (Ms) and coercivity (Hc) of the annealed specimens increased by increasing of Fe/Ba molar ratio. XRD results confirmed by those obtained from DTA/TGA and VSM, indicated that the Fe/Ba molar ratio of 12 is favorable for the formation of single-phase barium hexaferrite

  13. Effect of replacing RE and TM on magnetic properties and thermal stability of some Al–Ni-based amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Uporov, S.A., E-mail: segga@bk.ru [Institute of Metallurgy UB RAS, Ekaterinburg (Russian Federation); Uporova, N.S. [Ural State Pedagogical University, Ekaterinburg (Russian Federation); Bykov, V.A.; Kulikova, T.V.; Pryanichnikov, S.V. [Institute of Metallurgy UB RAS, Ekaterinburg (Russian Federation)

    2014-02-15

    Highlights: ► X-ray diffraction analysis of the quenched Al–Ni-based alloys revealed a clear prepeak. ► The amorphous alloys demonstrate the superparamagnetic behavior. ► The variation of the RE and TM caused the radical changes of thermal properties. -- Abstract: Amorphous ribbons Al{sub 86}Ni{sub 8}Ho{sub 6}, Al{sub 86}Ni{sub 8}Gd{sub 6} and Al{sub 86}Ni{sub 6}Co{sub 2}Gd{sub 4}Y{sub 2} were prepared by quenching from 1580–1600 K using spinning technique at a wheel speed of 32 m/s. X-ray diffraction (XRD) analysis of the quenched alloys revealed a clear prepeak located below the main amorphous peak. The specimens crystallize in three stages but glass transition temperature was not found. The crystalinity was calculated by both XRD and differential scanning calorimetry (DSC) methods for all samples. Magnetic properties of ribbons were investigated in wide ranges of temperature (T = 4–900 K) and magnetic field (up to 30 kOe) by Faraday method and vibration sample magnetometry (VSM). The amorphous alloys investigated have no magnetic ordering at low temperatures down to T = 4 K but demonstrate the superparamagnetic behavior. The magnetic properties are discussed in the frames of conception of existence the superparamagnetic clusters with ferrimagnetic ordering.

  14. Effect of replacing RE and TM on magnetic properties and thermal stability of some Al–Ni-based amorphous alloys

    International Nuclear Information System (INIS)

    Highlights: ► X-ray diffraction analysis of the quenched Al–Ni-based alloys revealed a clear prepeak. ► The amorphous alloys demonstrate the superparamagnetic behavior. ► The variation of the RE and TM caused the radical changes of thermal properties. -- Abstract: Amorphous ribbons Al86Ni8Ho6, Al86Ni8Gd6 and Al86Ni6Co2Gd4Y2 were prepared by quenching from 1580–1600 K using spinning technique at a wheel speed of 32 m/s. X-ray diffraction (XRD) analysis of the quenched alloys revealed a clear prepeak located below the main amorphous peak. The specimens crystallize in three stages but glass transition temperature was not found. The crystalinity was calculated by both XRD and differential scanning calorimetry (DSC) methods for all samples. Magnetic properties of ribbons were investigated in wide ranges of temperature (T = 4–900 K) and magnetic field (up to 30 kOe) by Faraday method and vibration sample magnetometry (VSM). The amorphous alloys investigated have no magnetic ordering at low temperatures down to T = 4 K but demonstrate the superparamagnetic behavior. The magnetic properties are discussed in the frames of conception of existence the superparamagnetic clusters with ferrimagnetic ordering

  15. Non-thermal Gamma-ray Emission from Delayed Pair Breakdown in a Magnetized and Photon-rich Outflow

    CERN Document Server

    Gill, Ramandeep

    2014-01-01

    We consider delayed, volumetric heating in a magnetized outflow that has broken out of a confining medium and expanded to a high Lorentz factor ($\\Gamma \\sim 10^2-10^3$) and low optical depth to scattering ($\\tau_{\\rm T} \\sim 10^{-3}-10^{-2}$). The energy flux at breakout is dominated by the magnetic field, with a modest contribution from quasi-thermal gamma rays whose spectrum was calculated in Paper I. We focus on the case of extreme baryon depletion in the magnetized material, but allow for a separate baryonic component that is entrained from a confining medium. Dissipation is driven by relativistic motion between these two components, which develops once the photon compactness drops below $ 4\\times 10^3(Y_e/0.5)^{-1}$. We first calculate the acceleration of the magnetized component following breakout, showing that embedded MHD turbulence provides significant inertia, the neglect of which leads to unrealistically high estimates of flow Lorentz factor. After re-heating begins, the pair and photon distributi...

  16. Structural, thermal, magnetic and optical characterization of undoped nanocrystalline ZnS prepared by solid state reaction

    International Nuclear Information System (INIS)

    Highlights: • Nanocrystalline zinc blende and wurtzite ZnS phases produced by mechanical alloying. • Sulfur and/or zinc vacancies in the ZnS as-milled. • Magnetic and semiconductor behavior for the as-milled ZnS-10h. • Irreversible demagnetization and Curie temperature above room temperature. • Structural stability after annealing and aged of the ZnS-10h sample. -- Abstract: Nanocrystalline zinc blende and wurtzite ZnS phases with sulfur and/or zinc vacancies were obtained from a mechanically alloyed Zn50S50 powder mixture. Structural, thermal, magnetic, optical and photoacoustic studies were carried out using X-ray diffraction, transmission electron microscopy, differential scanning calorimetry, vibrating sample magnetometer, UV–Vis absorption, photoluminescence and photoacoustic spectroscopy techniques. The cubic zinc blende (ZnSZB) and hexagonal wurtzite (ZnSWZ) phases were nucleated in 3 h of milling and remained until 10 h when the milling process was stopped. The coexistence of these two phases was confirmed by high resolution transmission electron microscopy. X-ray diffraction measurements attested the structural stability of the sample milled for 10 h and aged for eighteen months and of the sample milled 10 h and annealed at 300 °C and 600 °C. Differential scanning calorimetry measurements showed the unreacted sulfur in molecular form (rings and/or chains). Magnetic behavior was observed for as-milled sample and Curie temperature was estimated at 430 °C. Moreover, an irreversible behavior of magnetic properties was observed and correlated with changes on the structural vacancies densities. The UV–Vis absorption spectra and McLean analysis showed an optical band gap around 3.4 eV and 3.9 for ZnSZB and ZnSWZ phases, respectively. The sample milled for 10 h showed low blue photoemission intensity centered at 470 nm and thermal diffusivity around 0.02 cm2/s

  17. Stochastic effect on thermally magnetization reversal in Pico second ordering process

    International Nuclear Information System (INIS)

    In this study a magnetization reversal dynamics observed in the heat assisted magnetization reversal of CoPtCr perpendicularly magnetized material in the order of a pico second ordering time. Observation of heat assisted magnetization reversal have been using micromagnetic simulation solved by the Landau-Lifshitz-Gilbert equation. The magnetic dot size of the simulation was 50 nm × 50 nm × 20 nm. The perpendicularly anisotropy constant CoPtCr was 2 × 106 erg/cc. Micro-magnetic simulations was carried out systematically by providing pulse-external field with varying pulse duration of 25 ps to 1 ns. The decrease of the minimum field required for reversal observed in this simulation until it reached 90% for 125 ps cooled ordering time. The results also was showed that this sequence simulation running had a zero probability of switching at zero fields. It was indicated that the heat stochastic effect dominated in the mechanism reduced of the field was required for along to the magnetic field direction

  18. Magnetic and Thermal Properties of TmV2Al20 Single Crystals

    Science.gov (United States)

    Lei, Qiankun; Namiki, Takahiro; Isikawa, Yosikazu; Nishimura, Katsuhiko; Hutchison, Wayne D.

    2016-03-01

    The magnetization and specific heat of TmV2Al20 single crystals were measured in the temperature range from 0.5 to 300 K in external magnetic fields up to 7 T. TmV2Al20 was found to be paramagnetic above 0.5 K. Clear magnetic anisotropy was observed along the three principal crystallographic axes in the field above 1 T at 0.5 K. The magnetically easy axis is along the [100] direction, and the hard axis is along the [111] direction. On cooling below 2 K in zero external field, the magnetic part of specific heat divided by temperature, Cmag/T, increases up to 6 J/mol K2 near 0.6 K. The magnetic entropy in zero field reaches R ln 5 near 10 K, suggesting that the ground state of Tm3+ ions is a nonmagnetic doublet state with the first excited state of a magnetic triplet state nearby (a pseudo-fivefold degenerate state). The experimental results were reproduced by the crystalline electric field calculations, and an energy level scheme was proposed. The enhanced value of Cmag/T in the lowest temperature region in zero field was explained by assuming an energy splitting of the doublet ground state.

  19. Suppression of Parallel Transport in Turbulent Magnetized Plasmas and Its Impact on Non-Thermal and Thermal Aspects of Solar Flares

    Science.gov (United States)

    Emslie, A. Gordon; Bian, Nicolas H.; Kontar, Eduard

    2016-05-01

    Motivated by recent RHESSI observations that point to the existence of a mechanism that confines electrons to the coronal parts of flare loops more effectively than Coulomb collisions, we consider the impact of pitch-angle scattering off turbulent magnetic fluctuations on the parallel transport of electrons in flaring coronal loops. It is shown that the presence of such a scattering mechanism in addition to Coulomb collisional scattering can significantly reduce the parallel thermal and electrical conductivities relative to their collisional values. We provide illustrative expressions for the resulting thermoelectric coefficients that relate the thermal flux and electrical current density to the temperature gradient and the applied electric field. We then evaluate the effect of these modified transport coefficients on several items of interest to the modeling of flares, including: the peak flare coronal temperature that can be attained, the post-impulsive-phase cooling time of heated coronal plasma, and the importance of the beam-neutralizing return current on both ambient heating and the energy loss rate of accelerated electrons. We also discuss the ways in which anomalous transport processes have an impact on the required overall energy content of accelerated electrons in solar flares.

  20. Airborne forest fire research

    Science.gov (United States)

    Mattingly, G. S.

    1974-01-01

    The research relating to airborne fire fighting systems is reviewed to provide NASA/Langley Research Center with current information on the use of aircraft in forest fire operations, and to identify research requirements for future operations. A literature survey, interview of forest fire service personnel, analysis and synthesis of data from research reports and independent conclusions, and recommendations for future NASA-LRC programs are included.

  1. Particulate airborne impurities

    OpenAIRE

    Wilkinson, Kai

    2013-01-01

    The cumulative effects of air pollutants are of principal concern in research on environmental protection in Sweden. Post-industrial society has imposed many limits on emitted air pollutants, yet the number of reports on the negative effects from them is increasing, largely due to human activity in the form of industrial emissions and increased traffic flows. Rising concerns over the health effects from airborne particulate matter (PM) stem from in vitro, in vivo, and cohort studies revealing...

  2. GRYPHON : Airborne lifestyle concept

    OpenAIRE

    Evers, Erik

    2014-01-01

    The result of the project, the Gryphon, is a helicopter concept designed for private use. The intention of the project has been to investigate how safe, personal airborne mobility could be an attractive transportation alternative in the future. As an aspirational concept the goal has been to inspire and show an exciting way to enjoy a modern, sustainable lifestyle close to nature without the need for conventional infrastructure.

  3. Calculation of thermal conductivity coefficients of electrons in magnetized dense matter

    CERN Document Server

    Bisnovatyi-Kogan, G S

    2016-01-01

    The solution of Boltzmann equation for plasma in magnetic field, with arbitrarily degenerate electrons and non-degenerate nuclei, is obtained by Chapman-Enskog method. Functions, generalizing Sonin polynomials are used for obtaining an approximate solution. Fully ionized plasma is considered. The tensor of the heat conductivity coefficients in non-quantized magnetic field is calculated. For non-degenerate and strongly degenerate plasma the asymptotic analytic formulas are obtained, which are compared with results of previous authors. The Lorentz approximation, with neglecting of electron-electron encounters, is asymptotically exact for strongly degenerate plasma. For non-degenerate plasma the solution at 3-function approximation for Lorentz gas deviate from the exact solution for about 2.2\\%, at zero magnetic field. We obtain the solution for the heat conductivity tensor for the case of non-degenerate electrons, in presence of a magnetic field, in three polynomial approximation with account of electron-electr...

  4. Influence of Thermal Treatment on Magnetic Properties of Steel Sheet Material Utilised in Cable Routing System

    OpenAIRE

    Elemir Usak

    2013-01-01

    The influence of relax annealing aimed at removal of the residual stresses (so-called stress-relief annealing) on various magnetic parameters, such as the relative magnetic amplitude permeability, coercivity, remanent flux density, etc. is discussed. Samples of steel cable tray material which is a part of commercially available cable routing system were investigated in order to find information about the properties important from the point of view of EMC requirements in extremely demanding in...

  5. Influence of thermal treatment on magnetic properties of steel sheet material utilised in cable routing system

    OpenAIRE

    Ušák, Elemír

    2013-01-01

    The influence of relax annealing aimed at removal of the residual stresses (so-called stress-relief annealing) on various magnetic parameters, such as the relative magnetic amplitude permeability, coercivity, remanent flux density, etc. is discussed. Samples of steel cable tray material which is a part of commercially available cable routing system were investigated in order to find information about the properties important from the point of view of EMC requirements in extremely demanding in...

  6. Airborne wireless communication systems, airborne communication methods, and communication methods

    Science.gov (United States)

    Deaton, Juan D.; Schmitt, Michael J.; Jones, Warren F.

    2011-12-13

    An airborne wireless communication system includes circuitry configured to access information describing a configuration of a terrestrial wireless communication base station that has become disabled. The terrestrial base station is configured to implement wireless communication between wireless devices located within a geographical area and a network when the terrestrial base station is not disabled. The circuitry is further configured, based on the information, to configure the airborne station to have the configuration of the terrestrial base station. An airborne communication method includes answering a 911 call from a terrestrial cellular wireless phone using an airborne wireless communication system.

  7. Magnetorelaxometry for localization and quantification of magnetic nanoparticles for thermal ablation studies

    Science.gov (United States)

    Richter, H.; Kettering, M.; Wiekhorst, F.; Steinhoff, U.; Hilger, I.; Trahms, L.

    2010-02-01

    In magnetic heating treatments, intratumorally injected superparamagnetic iron oxide nanoparticles (MNP) exposed to an externally applied alternating magnetic field generate heat, specifically at the tumor region. This inactivates cancer cells with minimal side effects to the normal tissue. Therefore, the quantity of MNP needs to be thoroughly controlled to govern adequate heat production. Here, we demonstrate the capability of magnetorelaxometry (MRX) for the non-invasive quantification and localization of MNP accumulation in small animal models. The results of our MRX measurements using a multichannel vector magnetometer system with 304 SQUIDs (superconductive quantum interference device) on three mice hosting different carcinoma models (9L/lacZ and MD-AMB-435) are presented. The position and magnitude of the magnetic moment are reconstructed from measured spatial magnetic field distributions by a magnetic dipole model fit applying a Levenberg-Marquadt algorithm. Therewith, the center of gravity and the total amount of MNP accumulation in the mice are determined. Additionally, for a fourth mouse the distribution of MNP over individual organs and the tumor is analyzed by single-channel SQUID measurements, obtaining a sensitive spatial quantification. This study shows that magnetorelaxometry is well suited to monitor MNP accumulation before cancer therapy, with magnetic heating being an important precondition for treatment success.

  8. Magnetorelaxometry for localization and quantification of magnetic nanoparticles for thermal ablation studies

    Energy Technology Data Exchange (ETDEWEB)

    Richter, H; Wiekhorst, F; Steinhoff, U; Trahms, L [Physikalisch-Technische Bundesanstalt, Abbestrasse 2-12, 10587 Berlin (Germany); Kettering, M; Hilger, I [Institute of Diagnostic and Interventional Radiology, University Hospital Jena, Jena (Germany)], E-mail: heike.richter@ptb.de, E-mail: lutz.trahms@ptb.de, E-mail: Ingrid.hilger@med.uni-jena.de

    2010-02-07

    In magnetic heating treatments, intratumorally injected superparamagnetic iron oxide nanoparticles (MNP) exposed to an externally applied alternating magnetic field generate heat, specifically at the tumor region. This inactivates cancer cells with minimal side effects to the normal tissue. Therefore, the quantity of MNP needs to be thoroughly controlled to govern adequate heat production. Here, we demonstrate the capability of magnetorelaxometry (MRX) for the non-invasive quantification and localization of MNP accumulation in small animal models. The results of our MRX measurements using a multichannel vector magnetometer system with 304 SQUIDs (superconductive quantum interference device) on three mice hosting different carcinoma models (9L/lacZ and MD-AMB-435) are presented. The position and magnitude of the magnetic moment are reconstructed from measured spatial magnetic field distributions by a magnetic dipole model fit applying a Levenberg-Marquadt algorithm. Therewith, the center of gravity and the total amount of MNP accumulation in the mice are determined. Additionally, for a fourth mouse the distribution of MNP over individual organs and the tumor is analyzed by single-channel SQUID measurements, obtaining a sensitive spatial quantification. This study shows that magnetorelaxometry is well suited to monitor MNP accumulation before cancer therapy, with magnetic heating being an important precondition for treatment success.

  9. Suppression and control of thermal fatigue by an active flow control magnet (AFCOM) ; construction of MHD simulant flow loop using liquid-gallium

    International Nuclear Information System (INIS)

    This study proposes a portable type of active flow control magnet (AFCOM) which would comprehensively solve thermal hydraulic issues such as thermal fatigue, flow-induced vibration, cavitation, etc. concerned in a sodium-cooled fast reactor. This AFCOM technology utilizes electromagnetic force that negatively affects for conducting fluid in general. To begin with, the applicability of the AFCOM technology to the sodium thermal hydraulic issues is evaluated from the thermal and MHD points of view and then, the details of a newly constructed flow test loop, which uses liquid gallium as the simulant of sodium, are reported, including the safety and corrosive issues of gallium. (author)

  10. Magnetic thermal hysteresis due to paramagnetic-antiferromagnetic transition in Fe-24.4Mn-5.9Si-5.1Cr alloy

    Directory of Open Access Journals (Sweden)

    L. Wang

    2013-08-01

    Full Text Available Magnetic thermal hysteresis (MTH associated with a paramagnetic (PM-antiferromagnetic (AFM phase transition was found in an Fe-24.4Mn-5.9Si-5.1Cr shape-memory alloy. Aside from the magnetic field (H, the driving rate (v can also tune the critical temperature of the magnetic transition and cause an increase in MTH. The magnetic phase diagram obtained is discussed. The equation for MTH was deduced based on the Landau model for a PM-AFM transition that includes H and v dependence, which gives a reasonable account of the experimental results.

  11. Evaluation of thermal recovery of neutron-irradiated SA508-3 steel using magnetic property measurements

    International Nuclear Information System (INIS)

    The Vickers microhardness and magnetic properties have been used to investigate irradiation effects and thermal recovery characteristics of neutron-irradiated SA508-3 reactor pressure vessel steel specimens irradiated to a neutron fluence of 5.5 x 1017 n cm-2 (E > 1 MeV) at 70oC. Two recovery stages were identified from the hardness results during isochronal annealing and the mechanism responsible for the two stages was explained using the results of Barkhausen noise on the basis of the interaction between radiation-induced defects and the magnetic domain wall. The neutron irradiation caused the coercivity to decrease, whereas the maximum induction increased. Barkhausen noise parameters associated with the domain-wall motion were decreased by neutron irradiation and recovered with subsequent heat treatments. From the sensitive changes in the Barkhausen noise upon annealing heat treatment, it is suggested that the Barkhausen noise measurements may be used as a useful tool for monitoring the early stage of the thermal recovery behaviour of neutron-irradiated reactor pressure vessel steels. (Author)

  12. Air-borne geophysical prospecting using Helicopter

    International Nuclear Information System (INIS)

    The air-borne geophysical prospecting can investigate geological properties widely and quickly. In this investigation, we applied 3-types of geophysical prospecting, those were Electro-magnetic, Magnetic, and Radiometric method. We can measure apparent resistivity of ground on Electro-magnetic method, radioactivity on Radiometric method, and magnetization on Magnetic method. We can measure also resistivity distribution in the depth direction by measuring electro magnetic response to various frequencies. Conducting measurement, analysis and interpretation of above-mentioned 3-geophysical properties, we solved the geological structure from the distribution of geophysical properties in this area. We also tried to study and discuss comparison and correspondence with the present geological map. The air-borne Electro-magnetic method showed that the regions distributed with Sarabetsu Formation and Isachi Formation, which mainly consists of sandstone and conglomerate, have high apparent resistivity about 30-500 Ω·m. The regions distributed with Kowama Formation, Wakkanai Formation and Mashihoro Formation (Upper Mudstone Layer), which mainly consists of mudrock, have low resistivity 1-10 Ω·m in the depth over than dozens of meters, though some area dozens of meter below the surface have high resistivity about 50-200 Ω·m. Magnetic method showed that magnetization tends to decrease from southwest to northeast and this result corresponded with previous large scale magnetic intensity map (Geological Survey of Japan, 1992). High magnetic anomaly area, which spread from north-northwest to south-southeast, is found on a boundary between Sarabetsu and Isachi formation. Mashihoro formation, which is located east side of Nukanan fault, has also high magnetic anomaly area. Radiometric method showed that high radioactivity areas are distributed in alluvial depressions along Tenshio river and small river in the hill, while low radioactivity area are distributed in Tertiary

  13. Thermal evolution of nanocrystalline co-sputtered Ni–Zr alloy films: Structural, magnetic and MD simulation studies

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharya, Debarati, E-mail: debarati@barc.gov.in [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Rao, T.V. Chandrasekhar; Bhushan, K.G. [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Ali, Kawsar [Material Science Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Debnath, A. [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Singh, S. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Arya, A. [Material Science Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Bhattacharya, S. [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Basu, S. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2015-11-15

    Monophasic and homogeneous Ni{sub 10}Zr{sub 7} nanocrystalline alloy films were successfully grown at room temperature by co-sputtering in an indigenously developed three-gun DC/RF magnetron sputtering unit. The films could be produced with long-range crystallographic and chemical order in the alloy, thus overcoming the widely acknowledged inherent proclivity of the glass forming Ni–Zr couple towards amorphization. Crystallinity of these alloys is a desirable feature with regard to improved efficacy in applications such as hydrogen storage, catalytic activity and nuclear reactor engineering, to name a few. Thermal stability of this crystalline phase, being vital for transition to viable applications, was investigated through systematic annealing of the alloy films at 473 K, 673 K and 923 K for various durations. While the films were stable at 473 K, the effect of annealing at 673 K was to create segregation into nanocrystalline Ni (superparamagnetic) and amorphous Ni + Zr (non-magnetic) phases. Detailed analyses of the physical and magnetic structures before and after annealing were performed through several techniques effectual in analyzing stratified configurations and the findings were all consistent with each other. Polarized neutron and X-ray reflectometry, grazing incidence x-ray diffraction, time-of-flight secondary ion mass spectroscopy and X-ray photoelectron spectroscopy were used to gauge phase separation at nanometer length scales. SQUID based magnetometry was used to investigate macroscopic magnetic properties. Simulated annealing performed on this system using molecular dynamic calculations corroborated well with the experimental results. This study provides a thorough understanding of the creation and thermal evolution of a crystalline Ni–Zr alloy. - Highlights: • Nanocrystalline Ni{sub 10}Zr{sub 7} alloy thin films deposited successfully by co-sputtering. • Creation of a crystalline alloy in a binary system with a tendency to amorphize.

  14. Structural and magnetic effects on thermal emittance of La{sub 1−x}Sr{sub x}MnO{sub 3} from the first principles calculation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jiang-Fei [State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Department of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050 (China); Tang, Fu-Ling, E-mail: tfl03@mails.tsinghua.edu.cn [State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Department of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050 (China); Xue, Hong-Tao; Lu, Wen-Jiang [State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Department of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050 (China); Feng, Yu-Dong [Science and Technology on Surface Engineering Laboratory, Lanzhou Institute of Physics, Lanzhou 730000 (China)

    2015-09-15

    Generalized gradient approximation (GGA) exchange-correlation functional was used in the first-principles method to calculate thermal emittance of La{sub 1−x}Sr{sub x}MnO{sub 3} (LSMO). The effects of structure and magnetism on thermal emittance of LSMO were systematically investigated by the complex dielectric function. It is found that the LSMO with orthorhombic structure has a higher thermal emittance than that with rhombohedral structure at the same temperature. When the magnetism varying with temperature of LSMO is put into consideration, the magnetic different make a significant change on thermal emittance and the variation of thermal emittance of La{sub 0.75}Sr{sub 0.25}MnO{sub 3} is the biggest among x=0, 0.2, 0.25, 0.5. It is found that thermal emittance have a low value at the low temperature and have a high value at the high temperature, due to the unique feature of variable thermal emittance based on metal-insulator transition, which makes LSMO attractive as potential thermal control materials. - Highlights: • The emittance of La{sub 1-x}Sr{sub x}MnO{sub 3} (LSMO) varies with different magnetism state. • Orthorhombic LSMO has larger emittance than rhombohedral LSMO at same temperature. • If the magnetism varying with temperature of LSMO is considered, the variation of emittance of La{sub 0.75}Sr{sub 0.25}MnO{sub 3} is the biggest among x=0, 0.2, 0.25 and 0.5.

  15. Magneto-Thermal Stability in LARP Nb3Sn TQS Magnets

    CERN Document Server

    Bordini, B; Caspi, S; Dietderich, D; Felice, H; Ferracin, P; Rossi, L; Sabbi, G L; Takala, E

    2010-01-01

    In the framework of the US LHC Accelerator Program (LARP), three US laboratories BNL, FNAL and LBNL are developing Nb3Sn quadrupole magnets for the Large Hadron Collider (LHC) luminosity upgrade. At present CERN is supporting this activity by testing some of the LARP 1 m long 90 mm aperture magnets. Recently two magnets using a shell based key and bladder technology (TQS) have been tested at CERN. These magnets (TQS02c, TQS03a) share the same mechanical structure and use a 27 strand Rutherford cable based one on the 0.7 mm RRP® strand produced by Oxford Superconducting Technology (OST). The main difference between the two magnets is the strand sub-element layout (54/61 in TQS02c versus 108/127 in TQS03a) and the strand critical current. The TQS03a wire has a significantly lower critical current, a larger amount of copper stabilizer, and a larger number of superconducting sub-elements with respect to the TQS02c strand. The tests show that TQS02c was stable between 4.3 K and 2.7 K while it was limited by the s...

  16. Hysteretic magnetoresistance and thermal bistability in a magnetic two-dimensional hole system

    CERN Document Server

    Wurstbauer, Ursula; Weiss, Dieter; Dietl, Tomasz; Wegscheider, Werner; 10.1038/nphys1782

    2011-01-01

    Colossal negative magnetoresistance and the associated field-induced insulator-to-metal transition, the most characteristic features of magnetic semiconductors, are observed in n-type rare earth oxides and chalcogenides, p-type manganites, n-type and p-type diluted magnetic semiconductors (DMS) as well as in quantum wells of n-type DMS. Here, we report on magnetostransport studies of Mn modulation-doped InAs quantum wells, which reveal a magnetic field driven and bias voltage dependent insulator-to-metal transition with abrupt and hysteretic changes of resistance over several orders of magnitude. These phenomena coexist with the quantised Hall effect in high magnetic fields. We show that the exchange coupling between a hole and the parent Mn acceptor produces a magnetic anisotropy barrier that shifts the spin relaxation time of the bound hole to a 100 s range in compressively strained quantum wells. This bistability of the individual Mn acceptors explains the hysteretic behaviour while opening prospects for i...

  17. Thermal magnetic resonance: physics considerations and electromagnetic field simulations up to 23.5 Tesla (1GHz)

    International Nuclear Information System (INIS)

    Glioblastoma multiforme is the most common and most aggressive malign brain tumor. The 5-year survival rate after tumor resection and adjuvant chemoradiation is only 10 %, with almost all recurrences occurring in the initially treated site. Attempts to improve local control using a higher radiation dose were not successful so that alternative additive treatments are urgently needed. Given the strong rationale for hyperthermia as part of a multimodal treatment for patients with glioblastoma, non-invasive radio frequency (RF) hyperthermia might significantly improve treatment results. A non-invasive applicator was constructed utilizing the magnetic resonance (MR) spin excitation frequency for controlled RF hyperthermia and MR imaging in an integrated system, which we refer to as thermal MR. Applicator designs at RF frequencies 300 MHz, 500 MHz and 1GHz were investigated and examined for absolute applicable thermal dose and temperature hotspot size. Electromagnetic field (EMF) and temperature simulations were performed in human voxel models. RF heating experiments were conducted at 300 MHz and 500 MHz to characterize the applicator performance and validate the simulations. The feasibility of thermal MR was demonstrated at 7.0 T. The temperature could be increased by ~11 °C in 3 min in the center of a head sized phantom. Modification of the RF phases allowed steering of a temperature hotspot to a deliberately selected location. RF heating was monitored using the integrated system for MR thermometry and high spatial resolution MRI. EMF and thermal simulations demonstrated that local RF hyperthermia using the integrated system is feasible to reach a maximum temperature in the center of the human brain of 46.8 °C after 3 min of RF heating while surface temperatures stayed below 41 °C. Using higher RF frequencies reduces the size of the temperature hotspot significantly. The opportunities and capabilities of thermal magnetic resonance for RF hyperthermia interventions

  18. Airborne Tactical Free-Electron Laser

    Energy Technology Data Exchange (ETDEWEB)

    Whitney, Roy; Neil, George

    2007-02-01

    The goal of 100 kilowatts (kW) of directed energy from an airborne tactical platform has proved challenging due to the size and weight of most of the options that have been considered. However, recent advances in Free-Electron Lasers appear to offer a solution along with significant tactical advantages: a nearly unlimited magazine, time structures for periods from milliseconds to hours, radar like functionality, and the choice of the wavelength of light that best meets mission requirements. For an Airborne Tactical Free-Electron Laser (ATFEL) on a platforms such as a Lockheed C-130J-30 and airships, the two most challenging requirements, weight and size, can be met by generating the light at a higher harmonic, aggressively managing magnet weights, managing cryogenic heat loads using recent SRF R&D results, and using FEL super compact design concepts that greatly reduce the number of components. The initial R&D roadmap for achieving an ATFEL is provided in this paper. Performing this R&D is expected to further reduce the weight, size and power requirements for the FELs the Navy is currently developing for shipboard applications, as well as providing performance enhancements for the strategic airborne MW class FELs. The 100 kW ATFEL with its tactical advantages may prove sufficiently attractive for early advancement in the queue of deployed FELs.

  19. Thermally stable voltage-controlled perpendicular magnetic anisotropy in Mo|CoFeB|MgO structures

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiang, E-mail: xiang.li@ucla.edu; Yu, Guoqiang; Wong, Kin; Upadhyaya, Pramey; Akyol, Mustafa; Wang, Kang L., E-mail: wang@seas.ucla.edu [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); Wu, Hao; Han, Xiufeng [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Ong, P. V.; Kioussis, Nicholas [Department of Physics and Astronomy, California State University Northridge, Northridge, California 91330 (United States); Hu, Qi; Ebrahimi, Farbod [Inston Inc., Los Angeles, California 90095 (United States); Khalili Amiri, Pedram, E-mail: pedramk@ucla.edu [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); Inston Inc., Los Angeles, California 90095 (United States)

    2015-10-05

    We study voltage-controlled magnetic anisotropy (VCMA) and other magnetic properties in annealed Mo|CoFeB|MgO layered structures. The interfacial perpendicular magnetic anisotropy (PMA) is observed to increase with annealing over the studied temperature range, and a VCMA coefficient of about 40 fJ/V-m is sustained after annealing at temperatures as high as 430 °C. Ab initio electronic structure calculations of interfacial PMA as a function of strain further show that strain relaxation may lead to the increase of interfacial PMA at higher annealing temperatures. Measurements also show that there is no significant VCMA and interfacial PMA dependence on the CoFeB thickness over the studied range, which illustrates the interfacial origin of the anisotropy and its voltage dependence, i.e., the VCMA effect. The high thermal annealing stability of Mo|CoFeB|MgO structures makes them compatible with advanced CMOS back-end-of-line processes, and will be important for integration of magnetoelectric random access memory into on-chip embedded applications.

  20. Thermally stable voltage-controlled perpendicular magnetic anisotropy in Mo|CoFeB|MgO structures

    International Nuclear Information System (INIS)

    We study voltage-controlled magnetic anisotropy (VCMA) and other magnetic properties in annealed Mo|CoFeB|MgO layered structures. The interfacial perpendicular magnetic anisotropy (PMA) is observed to increase with annealing over the studied temperature range, and a VCMA coefficient of about 40 fJ/V-m is sustained after annealing at temperatures as high as 430 °C. Ab initio electronic structure calculations of interfacial PMA as a function of strain further show that strain relaxation may lead to the increase of interfacial PMA at higher annealing temperatures. Measurements also show that there is no significant VCMA and interfacial PMA dependence on the CoFeB thickness over the studied range, which illustrates the interfacial origin of the anisotropy and its voltage dependence, i.e., the VCMA effect. The high thermal annealing stability of Mo|CoFeB|MgO structures makes them compatible with advanced CMOS back-end-of-line processes, and will be important for integration of magnetoelectric random access memory into on-chip embedded applications

  1. Excitation of plasma waves by unstable photoelectron and thermal electron populations on closed magnetic field lines in the Martian ionosphere

    Directory of Open Access Journals (Sweden)

    N. Borisov

    2005-06-01

    Full Text Available It is argued that anisotropic electron pitch angle distributions in the closed magnetic field regions of the Martian ionosphere gives rise to excitation of plasma instabilities. We discuss two types of instabilities that are excited by two different populations of electrons. First, the generation of Langmuir waves by photoelectrons with energies of the order of 10eV is investigated. It is predicted that the measured anisotropy of their pitch angle distribution at the heights z≈400km causes excitation of waves with frequencies f~30kHz and wavelengths λ~30m. Near the terminators the instability of the electrostatic waves with frequencies of the order of or less than the electron gyrofrequency exited by thermal electrons is predicted. The typical frequencies of these waves depend on the local magnitude of the magnetic field and can achieve values f~3-5kHz above strong crustal magnetic fields.

  2. Magnetic properties and thermal treatments in pseudobinary TbPt1-xCux alloys

    International Nuclear Information System (INIS)

    The structural and magnetic properties of the TbPt1-xCux orthorhombic compounds are studied in two series of samples: prepared 'as quenched' and after an annealing treatment. An extended analysis of the influence of the annealing in the microstructure of the samples was performed by x-ray, neutron diffraction and scanning electron microscopy. This analysis allows us to understand the modifications in the magnetic properties of both series, as a consequence of the sample homogenization process. Changes from ferromagnetism to antiferromagnetism with increasing Cu concentration are found in both series despite the ionic distance invariance. x = 0.3 is the composition limit between both behaviours. This study strongly supports the importance of the conduction band state rather than ionic distances in the magnetic behaviour of these rare earth-d compounds

  3. Thermally robust Mo/CoFeB/MgO trilayers with strong perpendicular magnetic anisotropy

    OpenAIRE

    Liu, T; Y. Zhang; Cai, J. W.; Pan, H Y

    2014-01-01

    The recent discovery of perpendicular magnetic anisotropy (PMA) at the CoFeB/MgO interface has accelerated the development of next generation high-density non-volatile memories by utilizing perpendicular magnetic tunnel junctions (p-MTJs). However, the insufficient interfacial PMA in the typical Ta/CoFeB/MgO system will not only complicate the p-MTJ optimization, but also limit the device density scalability. Moreover, the rapid decreases of PMA in Ta/CoFeB/MgO films with annealing temperatur...

  4. Linear Stability Analysis of Thermal Convection in an Infinitely Long Vertical Rectangular Enclosure in the Presence of a Uniform Horizontal Magnetic Field

    Directory of Open Access Journals (Sweden)

    Takashi Kitaura

    2014-01-01

    Full Text Available Stability of thermal convection in an infinitely long vertical channel in the presence of a uniform horizontal magnetic field applied in the direction parallel to the hot and cold walls was numerically studied. First, in order to confirm accuracy of the present numerical code, the one-dimensional computations without the effect of magnetic field were computed and they agreed with a previous study quantitatively for various values of the Prandtl number. Then, linear stability analysis for the thermal convection flow in a square horizontal cross section under the magnetic field was carried out for the case of Pr = 0.025. The thermal convection flow was once destabilized at certain low Hartmann numbers, and it was stabilized at high Hartmann numbers.

  5. Thermal stability and the magnetic properties of hybrid vanadium oxide-tetradecylamine nanotubes

    Science.gov (United States)

    Saleta, M. E.; López, C. A.; Granada, M.; Troiani, H. E.; Sánchez, R. D.; Malta, M.; Torresi, R. M.

    2012-09-01

    Vanadium oxide nanotubes (NTs) were synthesized by the sol-gel method followed by a long-term hydrothermal treatment. The obtained nanotubes have a multiwall structure, and 70% of vanadium ions are in the V4+ state. This percentage was derived by evaluating three components of the magnetic susceptibility; namely, (i) the paramagnetic Curie-Weiss behavior, (ii) antiferromagnetic dimers, and (iii) magnetic trimers. The as-made NTs were annealed in situ in the cavity of the electron paramagnetic resonance (EPR) spectrometer. The line shape changes irreversibly at 390 K, and the EPR susceptibility presents an anomaly at 425 K. These changes are interpreted as a partial oxidation of the V4+ ions and consequently a decrease in the concentration of the magnetic species. The quantification of the V4+ ions of the annealed NTs reveals a diminution to 39% of V4+, a weakening of the Curie-Weiss and antiferromagnetic dimers contributions, and the suppression of magnetic trimers. Vibrational studies confirm the decrease of V4+ amount.

  6. A magnetic resonance study of 3d transition metals and thermal donors in silicon

    International Nuclear Information System (INIS)

    This thesis describes a study of 3d-transition metal impurities in silicon (titanium and iron in particular) and a study of oxygen-related heat-treatment centers in silicon, both carried out mainly by magnetic resonances techniques like EPR and ENDOR. 119 refs.; 31 figs.; 14 tabs

  7. Electrical, thermal and magnetic studies on Bi-substituted LSMO manganites

    Energy Technology Data Exchange (ETDEWEB)

    Daivajna, Mamatha D. [Department of Physics, Manipal Institute of Technology, Manipal University, Manipal 576104 (India); Rao, Ashok, E-mail: ashokanu_rao@rediffmail.com [Department of Physics, Manipal Institute of Technology, Manipal University, Manipal 576104 (India); Okram, G.S. [UGC-DAE Consortium for Scientific Research, University Campus, Indore 452017 (India)

    2015-08-15

    In the present investigation detailed electrical, magnetic and thermoelectric measurements on Bi-doped L{sub 0.6−x}Bi{sub x}Sr{sub 0.4}MnO{sub 3} (0≤x≤0.3) manganites have been done. All the samples are single phased. The metal-insulator transition temperatures (T{sub MI}) as well as the Curie temperature (T{sub C}) are both found to decrease with Bi-content. Magneto-resistance (MR) data shows that MR (%) increases with Bi-content thereby showing it can be used in magnetic memory based devices. Resistivity data shows that small polaron hopping (SPH) model is valid in high temperature regime. Low temperature resistivity data depicts that electron–electron scattering is mainly responsible for the conduction mechanism. High temperature thermoelectric power (TEP) data reaffirms the validity of SPH model. - Highlights: • The Bi-doped compounds follow small polaron hopping model in high temperature range. • Electrical resistivity data shows evidences about existence of magnetic polarons. • MR and TCR increase with Bi-content. • Potential bolometer and magnetic sensing materials.

  8. Nanocrystalline alloy Fe73.5Cu1Nb3Si13.5B9. Its structure and magnetic properties. II. Thermal stability of the induced magnetic anisotropy

    International Nuclear Information System (INIS)

    The specimens of alloy Fe73.5Cu1Nb3Si13.5B9 produced as amorphous ribbons by quenching from the melt to a rotating wheel are used to study thermal stability of a constant of magnetic anisotropy Ku, induced in the process of thermomechanical or thermomagnetic treatments. The conditions of magnetic anisotropy induction (holding time and the intensity of external action) for obtaining expected thermal stability of Ku, are elucidated. Transmission electron microscopical studies show some distinctions in the alloy microstructure after different treatments. A comparison of results of magnetic and structural investigations, carried out by Moessbauer method, permits the assumption that the phases containing niobium and boron along with iron are responsible for thermal stability of Ku

  9. Airborne radioactive contamination monitoring

    International Nuclear Information System (INIS)

    Current technologies for the detection of airborne radioactive contamination do not provide real-time capability. Most of these techniques are based on the capture of particulate matter in air onto filters which are then processed in the laboratory; thus, the turnaround time for detection of contamination can be many days. To address this shortcoming, an effort is underway to adapt LRAD (Long-Range-Alpha-Detection) technology for real-time monitoring of airborne releases of alpa-emitting radionuclides. Alpha decays in air create ionization that can be subsequently collected on electrodes, producing a current that is proportional to the amount of radioactive material present. Using external fans on a pipe containing LRAD detectors, controlled samples of ambient air can be continuously tested for the presence of radioactive contamination. Current prototypes include a two-chamber model. Sampled air is drawn through a particulate filter and then through the first chamber, which uses an electrostatic filter at its entrance to remove ambient ionization. At its exit, ionization that occurred due to the presence of radon is collected and recorded. The air then passes through a length of pipe to allow some decay of short-lived radon species. A second chamber identical to the first monitors the remaining activity. Further development is necessary on air samples without the use of particulate filtering, both to distinguish ionization that can pass through the initial electrostatic filter on otherwise inert particulate matter from that produced through the decay of radioactive material and to separate both of these from the radon contribution. The end product could provide a sensitive, cost-effective, real-time method of determining the presence of airborne radioactive contamination

  10. Airborne field strength monitoring

    Directory of Open Access Journals (Sweden)

    J. Bredemeyer

    2007-06-01

    Full Text Available In civil and military aviation, ground based navigation aids (NAVAIDS are still crucial for flight guidance even though the acceptance of satellite based systems (GNSS increases. Part of the calibration process for NAVAIDS (ILS, DME, VOR is to perform a flight inspection according to specified methods as stated in a document (DOC8071, 2000 by the International Civil Aviation Organization (ICAO. One major task is to determine the coverage, or, in other words, the true signal-in-space field strength of a ground transmitter. This has always been a challenge to flight inspection up to now, since, especially in the L-band (DME, 1GHz, the antenna installed performance was known with an uncertainty of 10 dB or even more. In order to meet ICAO's required accuracy of ±3 dB it is necessary to have a precise 3-D antenna factor of the receiving antenna operating on the airborne platform including all losses and impedance mismatching. Introducing precise, effective antenna factors to flight inspection to achieve the required accuracy is new and not published in relevant papers yet. The authors try to establish a new balanced procedure between simulation and validation by airborne and ground measurements. This involves the interpretation of measured scattering parameters gained both on the ground and airborne in comparison with numerical results obtained by the multilevel fast multipole algorithm (MLFMA accelerated method of moments (MoM using a complex geometric model of the aircraft. First results will be presented in this paper.

  11. An integrated study of thermal treatment effects on the microstructure and magnetic properties of Zn-ferrite nanoparticles.

    Science.gov (United States)

    Antic, Bratislav; Perovic, Marija; Kremenovic, Aleksandar; Blanusa, Jovan; Spasojevic, Vojislav; Vulic, Predrag; Bessais, Lotfi; Bozin, Emil S

    2013-02-27

    The evolution of the magnetic state, crystal structure and microstructure parameters of nanocrystalline zinc-ferrite, tuned by thermal annealing of ∼4 nm nanoparticles, was systematically studied by complementary characterization methods. Structural analysis of neutron and synchrotron x-ray radiation data revealed a mixed cation distribution in the nanoparticle samples, with the degree of inversion systematically decreasing from 0.25 in an as-prepared nanocrystalline sample to a non-inverted spinel structure with a normal cation distribution in the bulk counterpart. The results of DC magnetization and Mössbauer spectroscopy experiments indicated a superparamagnetic relaxation in ∼4 nm nanoparticles, albeit with different freezing temperatures T(f) of 27.5 K and 46 K, respectively. The quadrupole splitting parameter decreases with the annealing temperature due to cation redistribution between the tetrahedral and octahedral sites of the spinel structure and the associated defects. DC magnetization measurements indicated the existence of significant interparticle interactions among nanoparticles ('superspins'). Additional confirmation for the presence of interparticle interactions was found from the fit of the T(f)(H) dependence to the AT line, from which a value of the anisotropy constant of K(eff) = 5.6 × 10(5) erg cm(-3) was deduced. Further evidence for strong interparticle interactions was found from AC susceptibility measurements, where the frequency dependence of the freezing temperature T(f)(f) was satisfactory described by both Vogel-Fulcher and dynamic scaling theory, both applicable for interacting systems. The parameters obtained from these fits suggest collective freezing of magnetic moments at T(f). PMID:23343510

  12. An integrated study of thermal treatment effects on the microstructure and magnetic properties of Zn-ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Antic, Bratislav [Univ. of Belgrade (Serbia); Perovic, Marija [Univ. of Belgrade (Serbia); Kremenovic, Aleksandar [Univ. of Belgrade (Serbia); Blanusa, Jovan [Univ. of Belgrade (Serbia); Spasojevic, Vojislav [Univ. of Belgrade (Serbia); Vulic, Predrag [Univ. of Belgrade (Serbia); Bessais, Lotfi [Univ. of Paris (France); Bozin, Emil S [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-09-30

    The evolution of the magnetic state, crystal structure and microstructure parameters of nanocrystalline zinc–ferrite, tuned by thermal annealing of ~4 nm nanoparticles, was systematically studied by complementary characterization methods. Structural analysis of neutron and synchrotron x-ray radiation data revealed a mixed cation distribution in the nanoparticle samples, with the degree of inversion systematically decreasing from 0.25 in an as-prepared nanocrystalline sample to a non-inverted spinel structure with a normal cation distribution in the bulk counterpart. The results of DC magnetization and Mossbauer spectroscopy experiments indicated a superparamagnetic relaxation in ~4 nm nanoparticles, albeit with different freezing temperatures Tf of 27.5 K and 46 K, respectively. The quadrupole splitting parameter decreases with the annealing temperature due to cation redistribution between the tetrahedral and octahedral sites of the spinel structure and the associated defects. DC magnetization measurements indicated the existence of significant interparticle interactions among nanoparticles (‘superspins’). Additional confirmation for the presence of interparticle interactions was found from the fit of the Tf(H) dependence to the AT line, from which a value of the anisotropy constant of Keff = 5.6 × 105 erg cm-3 was deduced. Further evidence for strong interparticle interactions was found from AC susceptibility measurements, where the frequency dependence of the freezing temperature Tf(ƒ) was satisfactory described by both Vogel–Fulcher and dynamic scaling theory, both applicable for interacting systems. The parameters obtained from these fits suggest collective freezing of magnetic moments at Tf .

  13. Tripartite entanglement of {Cu3} single molecular magnet with magnetic field in thermal equilibrium%{Cu3}单分子磁体在热平衡和磁场作用下的三体纠缠∗

    Institute of Scientific and Technical Information of China (English)

    郑一丹; 周斌

    2016-01-01

    Quantum entanglement is one of the most fundamental properties of quantum mechanics. Because of the nonlocality, quantum entanglement is widely used in quantum computation and quantum information. Considering the fact that thermal fluctuation suppresses quantum effects, the concept of thermal entanglement is introduced to refer to the idea that the effect of temperature should be viewed as external control in the preparation of entangled state. It has been found that nanoscale single molecular magnet has a novel quantum effect at low temperature. Furthermore, single-molecular magnet is viewed as a promising candidate for realizing encoding and manipulation of quantum information. Na9[Cu3Na3(H2O)9(α-AsW9O33)2]·26H2O (denoted as {Cu3} for convenience) is one of the typical representatives of nanoscale single molecular magnets. In this paper, we will theoretically analyze the properties of tripartite entanglement in {Cu3} with an external magnetic field in thermal equilibrium. The tripartite negativity is used to characterize the tripartite entanglement. The tripartite negativity of {Cu3} single molecular magnet is calculated numerically by using the equivalent spin model and experimental fitting parameters. We consider the magnetic fields along the vertical and the parallel directions of triangular spin ring, respectively, and the case with a tilted magnetic field is also discussed in this paper. It is shown that the magnitude and direction of magnetic field, and temperature have importance effects on the tripartite negativity of the system. It is found that the larger extra strong magnetic field will inhibit the generation of the quantum state of tripartite entanglement at higher temperature. In addition, compared with the magnetic field along the parallel direction of triangular spin ring and the tilted magnetic field, the magnetic field along the vertical direction of triangular spin ring obtains larger values of tripartite negativity under the same temperature

  14. Determination of formal kinetic constants of thermal decomposition of aqueous hydrogen peroxide solution in a mixture of magnetic powder, based on experimental thermogram, obtained in adiabatic conditions

    Science.gov (United States)

    Zaripov, Jamshed; Borisov, Boris; Bondarchuk, Sergey

    2014-08-01

    Process of thermal decomposition of hydrogen peroxide aqueous solution with the addition of magnetic powder in the form of toner for printers and lanthanum manganite were considered. Obtained resulting from an experiment in the Dewar container conducted thermogram analyzed using mass balance equations and heat. Formal kinetic parameters determined, and conclude that the magnetic powder in the mixture does not have catalytic properties. The described technique is recommended as a rapid analysis of the kinetics of the various reactions to substances having predefined thermal and thermodynamic properties.

  15. Study of the insulating magnetic system Eusub(x)Srsub(1-x)S, in particular the phase spin glass of x approximately= 0.4 compounds by thermal measurements at low temperature and by electron magnetic resonance

    International Nuclear Information System (INIS)

    Properties at low temperature of Eusub(x)Srsub(1-x)S are studied by thermal measurements in a high magnetic field (0 <= H <= 7T). Thermal conductivity K in the temperature rang 60 mK - 50 K is determined on 3 monocrystals with x = 0.017 (paramagnetic), x = 0.44 (spin glass below Tg approximately= 2 K) and x = 1 (EuS ferromagnetic, Tsub(c) approximately= 16 K). Phonon diffusion by low energy magnetic excitation in the spin glass and phonon diffusion by magnons in EuS are evidenced. Specific heat C measured on the monocrystal x = 0.44 in the temperature range 0.7 K - 10 K shows a gap in high magnetic field. Electron magnetic resonance of a monocrystal of the spin glass Eusub(0.4)Srsub(0.6)S is studied in the temperature range 1.4 K - 300 K

  16. Thermal conductivity and viscosity of hybrid nanfluids prepared with magnetic nanodiamond-cobalt oxide (ND-Co3O4) nanocomposite

    OpenAIRE

    L. Syam Sundar; G.O. Irurueta; Venkata Ramana, E.; Singh, Manoj K.; A.C.M. Sousa

    2016-01-01

    Synthesis of magnetic nanodiamond-cobalt oxide (ND-Co3O4) nanocomposite material; preparation of nanofluids and estimation of thermal properties such as thermal conductivity and viscosity has been explained experimentally in this paper. The nanocomposite material has been synthesized by using in-situ growth technique and chemical coprecipitation between cobalt chloride and sodium borohydrate. The various techniques such as XRD, TEM, XPS and VSM have been used to confirm the ND and Co3O4 phase...

  17. Magnetic, electrical, thermal transport, and thermoelectric proberties of the ... and ... complex metallic alloy phases in the Al-Pd-Mn system

    OpenAIRE

    Dolinsek, J.; Jeglic, P.; Urban, K; McGuiness, P. J.; Jaglicic, Z.; Bilusic, A.; Bihar, Z.; Smontara, A.; Landauro, C.V.; Feuerbacher, M.; Grushko, B.

    2005-01-01

    The Al-Pd-Mn system of intermetallics contains complex metallic alloy (CMA) phases, whose crystal structures are based on giant unit cells comprising up to more than a thousand atoms per cell. We performed investigation of the magnetic, electrical, and thermal transport and thermoelectric properties of the xi(') phase and the related Psi phase on single-crystalline samples grown by the Bridgman technique. The samples are diamagnets with a tiny paramagnetic Curie-like magnetization and an esti...

  18. Design study of magnetic environments for XYZ polarization analysis using 3He for the new thermal time of flight spectrometer TOPAS

    CERN Document Server

    Salhi, Zahir; Ioffe, Alexander

    2012-01-01

    We present a finite element calculation of the magnetic field (MagNet software) taken with the newly proposed PASTIS Coil, which uses a wide-angle banana shaped 3He Neuton Spin Filter cell (NSF) to cover a large range of scattering angle. The goal of this insert is to enable XYZ polarization analysis to be installed on the future thermal time-of flight spectrometer TOPAS.

  19. Compositae dermatitis from airborne parthenolide

    DEFF Research Database (Denmark)

    Paulsen, E; Christensen, Lars Porskjær; Andersen, Klaus Ejner

    2007-01-01

    BACKGROUND: Compositae dermatitis confined to exposed skin has often been considered on clinical grounds to be airborne. Although anecdotal clinical and plant chemical reports suggest true airborne allergy, no proof has been procured. Feverfew (Tanacetum parthenium) is a European Compositae plant...

  20. Structural, thermal, magnetic and optical characterization of undoped nanocrystalline ZnS prepared by solid state reaction

    Energy Technology Data Exchange (ETDEWEB)

    Faita, F.L., E-mail: flffisica@yahoo.com.br [Departamento de Física, Universidade Federal de Santa Catarina, Campus Trindade, 88040-900 Florianópolis, SC (Brazil); Ersching, K. [Instituto Federal de Educação, Ciência e Tecnologia Catarinense – Campus Camboriú, 88340-000 Camboriú, SC (Brazil); Poffo, C.M. [Departamento de Física, Universidade Federal do Amazonas, 3000 Japiim, 69077000 Manaus, AM (Brazil); Benetti, L.C. [Departamento de Física, Universidade Federal de Santa Catarina, Campus Trindade, 88040-900 Florianópolis, SC (Brazil); Trichês, D.M.; Souza, S.M. [Departamento de Física, Universidade Federal do Amazonas, 3000 Japiim, 69077000 Manaus, AM (Brazil); Viegas, A.D.C.; Lima, J.C. de [Departamento de Física, Universidade Federal de Santa Catarina, Campus Trindade, 88040-900 Florianópolis, SC (Brazil)

    2014-03-25

    Highlights: • Nanocrystalline zinc blende and wurtzite ZnS phases produced by mechanical alloying. • Sulfur and/or zinc vacancies in the ZnS as-milled. • Magnetic and semiconductor behavior for the as-milled ZnS-10h. • Irreversible demagnetization and Curie temperature above room temperature. • Structural stability after annealing and aged of the ZnS-10h sample. -- Abstract: Nanocrystalline zinc blende and wurtzite ZnS phases with sulfur and/or zinc vacancies were obtained from a mechanically alloyed Zn{sub 50}S{sub 50} powder mixture. Structural, thermal, magnetic, optical and photoacoustic studies were carried out using X-ray diffraction, transmission electron microscopy, differential scanning calorimetry, vibrating sample magnetometer, UV–Vis absorption, photoluminescence and photoacoustic spectroscopy techniques. The cubic zinc blende (ZnS{sup ZB}) and hexagonal wurtzite (ZnS{sup WZ}) phases were nucleated in 3 h of milling and remained until 10 h when the milling process was stopped. The coexistence of these two phases was confirmed by high resolution transmission electron microscopy. X-ray diffraction measurements attested the structural stability of the sample milled for 10 h and aged for eighteen months and of the sample milled 10 h and annealed at 300 °C and 600 °C. Differential scanning calorimetry measurements showed the unreacted sulfur in molecular form (rings and/or chains). Magnetic behavior was observed for as-milled sample and Curie temperature was estimated at 430 °C. Moreover, an irreversible behavior of magnetic properties was observed and correlated with changes on the structural vacancies densities. The UV–Vis absorption spectra and McLean analysis showed an optical band gap around 3.4 eV and 3.9 for ZnS{sup ZB} and ZnS{sup WZ} phases, respectively. The sample milled for 10 h showed low blue photoemission intensity centered at 470 nm and thermal diffusivity around 0.02 cm{sup 2}/s.

  1. Electrical, Thermal, and Magnetic Characterization of Natural Tetrahedrites-Tennantites of Different Origin

    Science.gov (United States)

    Levinsky, P.; Vaney, J.-B.; Candolfi, C.; Dauscher, A.; Lenoir, B.; Hejtmánek, J.

    2016-03-01

    Naturally occurring sulfosalt minerals of the tetrahedrite-tennantite series ((Cu,Fe,Zn,Ag,Hg)12(Sb,As)4S13) are studied because of their potential use as basic components in the manufacture of thermoelectric devices for moderate-temperature applications. In the work reported herein, the chemical, crystallographic, thermoelectric, and magnetic properties of four specimens from different ores from Europe and America were exhaustively characterized. Our study revealed that these natural tetrahedrites usually behave as low-to-moderately doped p-type semiconductors with low mobility. Their carrier charge transport is thus located at the edge between hopping and itinerant mechanisms. The magnetic study, probing the behavior of the constituent iron species, revealed that an insignificant part of the iron occurs as ferromagnetic impurities. The dominant iron species is Fe2+ ions with antiferromagnetic interactions. The maximum value of ZT observed was 0.13 at 700 K; this value is impaired, primarily, by high electrical resistivity.

  2. Electrical, thermal and magnetic studies on Bi-substituted LSMO manganites

    Science.gov (United States)

    Daivajna, Mamatha D.; Rao, Ashok; Okram, G. S.

    2015-08-01

    In the present investigation detailed electrical, magnetic and thermoelectric measurements on Bi-doped L0.6-xBixSr0.4MnO3 (0≤x≤0.3) manganites have been done. All the samples are single phased. The metal-insulator transition temperatures (TMI) as well as the Curie temperature (TC) are both found to decrease with Bi-content. Magneto-resistance (MR) data shows that MR (%) increases with Bi-content thereby showing it can be used in magnetic memory based devices. Resistivity data shows that small polaron hopping (SPH) model is valid in high temperature regime. Low temperature resistivity data depicts that electron-electron scattering is mainly responsible for the conduction mechanism. High temperature thermoelectric power (TEP) data reaffirms the validity of SPH model.

  3. Synchronization of electrically coupled stochastic magnetic oscillators induced by thermal and electrical noise

    OpenAIRE

    Mizrahi, A.; Locatelli, N.; Grollier, J.; Querlioz, D.

    2016-01-01

    Superparamagnetic tunnel junctions are nanostructures that auto-oscillate stochastically under the effect of thermal noise. Recent works showed that despite their stochasticity, such junctions possess a capability to synchronize to subthreshold voltage drives, in a way that can be enhanced or controlled by adding noise. In this work, we investigate a system composed of two electrically coupled junctions, connected in series to a periodic voltage source. We make use of numerical simulations an...

  4. Airborne transmission of lyssaviruses.

    Science.gov (United States)

    Johnson, N; Phillpotts, R; Fooks, A R

    2006-06-01

    In 2002, a Scottish bat conservationist developed a rabies-like disease and subsequently died. This was caused by infection with European bat lyssavirus 2 (EBLV-2), a virus closely related to Rabies virus (RABV). The source of this infection and the means of transmission have not yet been confirmed. In this study, the hypothesis that lyssaviruses, particularly RABV and the bat variant EBLV-2, might be transmitted via the airborne route was tested. Mice were challenged via direct introduction of lyssavirus into the nasal passages. Two hours after intranasal challenge with a mouse-adapted strain of RABV (Challenge Virus Standard), viral RNA was detectable in the tongue, lungs and stomach. All of the mice challenged by direct intranasal inoculation developed disease signs by 7 days post-infection. Two out of five mice challenged by direct intranasal inoculation of EBLV-2 developed disease between 16 and 19 days post-infection. In addition, a simple apparatus was evaluated in which mice could be exposed experimentally to infectious doses of lyssavirus from an aerosol. Using this approach, mice challenged with RABV, but not those challenged with EBLV-2, were highly susceptible to infection by inhalation. These data support the hypothesis that lyssaviruses, and RABV in particular, can be spread by airborne transmission in a dose-dependent manner. This could present a particular hazard to personnel exposed to aerosols of infectious RABV following accidental release in a laboratory environment. PMID:16687600

  5. Airborne monitoring system

    International Nuclear Information System (INIS)

    A complete system for tracking, mapping, and performing a composition analysis of a radioactive plume and contaminated area was developed at the NRCN. The system includes two major units : An airborne unit for monitoring and a ground station for analyzing. The airborne unit is mounted on a helicopter and includes file following. Four radiation sensor, two 2'' x 2'' Nal (Tl) sensors horizontally separated by lead shield for mapping and spectroscopy, and two Geiger Mueller (GM) tubes as part of the safety system. A multichannel analyzer card is used for spectroscopy. A navigation system, based on GPS and a barometric altitude meter, is used to locate the plume or ground data. The telemetry system, consisting of a transceiver and a modem, transfers all the data in real time to the ground station. An industrial PC (Field Works) runs a dedicated C++ Windows application to manage the acquired data. An independent microprocessor based backup system includes a recorder, display, and key pad. The ground station is based on an industrial PC, a telemetry system, a color printer and a modem to communicate with automatic meteorology stations in the relevant area. A special software controls the ground station. Measurement results are analyzed in the ground station to estimate plume parameters including motion, location, size, velocity, and perform risk assessment. (authors)

  6. Thermal Quantum Discord in Pure Dzyaloshinskii—Moriya Model with Magnetic Field

    Science.gov (United States)

    Li, Da-Chuang; Li, Xiao-Man; Cao, Zhuo-Liang

    2016-06-01

    We investigate the effects of the directions of Dzyaloshinskii—Moriya (DM) interaction vector and magnetic field on the quantum discord in the pure DM model. For different directions of DM vector, we find that there are different optimal parameter components of magnetic field. Moreover, we find that the optimal parameter components rules are the same for the Hamiltonian H1 and H2. According to the rules, for a certain axial DM vector, we can get the maximal quantum discord by adjusting the direction of the external magnetic field, which is feasible under the current experimental technology. Supported by the National Natural Science Foundation of China under Grant Nos. 11204061, 11374085, 11104057, and 11204002, the Anhui Provincial Natural Science Foundation under Grant No. 1408085MA16, the Anhui Provincial Candidates for Academic and Technical Leaders Foundation under Grant No. 2015H052, the discipline top-notch talents Foundation and the Excellent Young Talents Support Plan of Anhui Provincial Universities. Ming Yang is supported by National Natural Science Foundation of China under Grant No. 11274010, the Specialized Research Fund for the Doctoral Program of Higher Education under Grant No. 20113401110002, the 211 Project of Anhui University, and the Personnel Department of Anhui Province

  7. Thermal Marangoni instability and magnetic pressure for a thin ferrofluid layer.

    Science.gov (United States)

    Hennenberg, Marcel; Slavtchev, Slavtcho; Weyssow, Boris

    2009-04-01

    We study the linear coupling between the Marangoni and Cowley-Rosensweig instabilities for a thin layer of ferrofluid subjected to a temperature gradient and a magnetic field. Both are perpendicular to the reference horizontal boundaries, one of which is a rigid plate, while the other is a free surface remaining flat as long as the magnetic field is smaller than the critical value of the onset of the static isothermal Cowley-Rosensweig instability. Our study considers at first a ferrofluid layer resting on the rigid border. In the stationary case, when heating is directed from the rigid side, a magnetic field, smaller than the Cowley-Rosensweig critical one, can induce a new pattern: the critical Marangoni number is much lower than in the nonmagnetic undeformable case, for a dimensionless wavenumber of O(square root Bo) less than 1.992, its Newtonian classical value. When heating from the gaseous phase, an oscillatory marginal case exists theoretically, but for unphysical conditions. We consider also the case when the ferrofluid is hanging down from the rigid side. Only the wavelength critical value of the Rayleigh-Taylor instability that separates a stable region from an unstable one changes. PMID:19426330

  8. Entanglement and Teleportation via Thermally Entangled State of Anisotropic Heisenberg XYZ Chain with Inhomogeneous External Magnetic Field

    Science.gov (United States)

    Ni, Hui-Ying; Fang, Jian-Xing; Zhu, Shi-Qun; Sha, Jin-Qiao; Jiang, Wei-Xing

    2008-02-01

    In this paper we study the entanglement in a two-qubit spin in the XYZ model, and teleport a two-qubit entangled state using this spin chain in the condition of the thermal equilibrium as a quantum channel. We investigate the effects of the interaction of z-component JZ, the inhomogeneous magnetic field b, the anisotropy γ, and the temperature T on the entanglement and fidelity. In order to characterize the quality of the teleported state, we research the average fidelity Fa. High average fidelity of the teleportation is obtained when the temperat ure is very low. Under some condition, we also find that when inhomogeneity increases to a certain value, the average fidelity can exhibit a larger revival than that for less values of b.

  9. Study of Heat Transfer with Nonlinear Thermal Radiation on Sinusoidal Motion of Magnetic Solid Particles in a Dusty Fluid

    Directory of Open Access Journals (Sweden)

    Bhatti M. M.

    2016-09-01

    Full Text Available In this article, heat transfer with nonlinear thermal radiation on sinusoidal motion of magnetic solid particles in a dust Jeffrey fluid has been studied. The effects of Magnetohydrodynamic (MHD and hall current are also taken under consideration. The governing equation of motion and energy equation are modelled with help of Ohms law for fluid and dust phases. The solutions of the resulting ordinary coupled partial differential equations are solved analytically. The impact of all the physical parameters of interest such as Hartmann number, slip parameter, Hall parameter, radiation parameter, Prandtl number, Eckert number and particle volume fraction are demonstrated mathematically and graphically. Trapping mechanism is also discussed in detail by drawing contour lines. The present analysis affirms many interesting behaviours, which permit further study on solid particles motion with heat and mass transfer.

  10. Phase composition, magnetic properties and thermal behavior of a novel Fe2O3-SiO2 composite material

    Science.gov (United States)

    Panasenko, Alexander E.; Tkachenko, Ivan A.; Zemnukhova, Ludmila A.; Shchetinin, Igor V.; Didenko, Nina A.

    2016-05-01

    An Fe2O3-SiO2 composite was prepared by controllable Fe3+ and SIO32- hydrolysis. Scanning (SEM) and transmitting (TEM) electron microscopy images showed particles with an average size of 10-30 nm composed of an iron-containing core covered with a silica shell. The FT-IR, vibrating sample magnitometer (VSM), thermogravimetric analysis and Mössbauer spectroscopy study confirmed that the core consisted of ferrihydrite. Heating at 300 °C did not result in any noticeable phase transitions, whereas 800 °C heating caused the formation of the maghemite γ-Fe2O3 phase. Such improvement of the thermal stability of maghemite is promising for development of heat-resistant magnetic materials.

  11. Thermal softening of metallic shaped-charge jets formed by the collapse of shaped-charge liners in the presence of a magnetic field

    Science.gov (United States)

    Fedorov, S. V.

    2016-05-01

    This paper presents an analysis of the possibility of increasing the ultimate stretching and penetration capability of metallic shaped-charge jets in the presence of an axial magnetic field in the shaped-charge liner due to heating and thermal softening of the jet material as a result of a sharp increase in the magnetic-field induction in the jet formation region upon liner collapse. This process is studied by numerical simulation in a quasi-two-dimensional formulation taking into account the inertial stretching of the conductive rigid-plastic rod in the presence of a longitudinal magnetic field in it.

  12. Calibration Matters: Advances in Strapdown Airborne Gravimetry

    Science.gov (United States)

    Becker, D.

    2015-12-01

    Using a commercial navigation-grade strapdown inertial measurement unit (IMU) for airborne gravimetry can be advantageous in terms of cost, handling, and space consumption compared to the classical stable-platform spring gravimeters. Up to now, however, large sensor errors made it impossible to reach the mGal-level using such type IMUs as they are not designed or optimized for this kind of application. Apart from a proper error-modeling in the filtering process, specific calibration methods that are tailored to the application of aerogravity may help to bridge this gap and to improve their performance. Based on simulations, a quantitative analysis is presented on how much IMU sensor errors, as biases, scale factors, cross couplings, and thermal drifts distort the determination of gravity and the deflection of the vertical (DOV). Several lab and in-field calibration methods are briefly discussed, and calibration results are shown for an iMAR RQH unit. In particular, a thermal lab calibration of its QA2000 accelerometers greatly improved the long-term drift behavior. Latest results from four recent airborne gravimetry campaigns confirm the effectiveness of the calibrations applied, with cross-over accuracies reaching 1.0 mGal (0.6 mGal after cross-over adjustment) and DOV accuracies reaching 1.1 arc seconds after cross-over adjustment.

  13. Investigation of Electromagnetic, Thermal and Mechanical Characteristics of a Five-Phase Dual-Rotor Permanent-Magnet Synchronous Motor

    Directory of Open Access Journals (Sweden)

    Jing Zhao

    2015-09-01

    Full Text Available This paper investigates of a kind of five-phase dual-rotor permanent-magnet synchronous motor (DRPMSM, which contains dual rotors and a single stator. This kind of motor has the potential advantages of high power density, high reliability and high efficiency, which make it more appropriate for using in electric vehicles (EVs. In order to evaluate the most suitable power level for this kind of structure, the electromagnetic, the thermal and the mechanical characteristics are investigated in this paper. The length to diameter ratio of motors is researched to obtain the highest power density and then the optimum ratio is obtained. Based on the optimum ratio, the thermal characteristics are researched under natural condition and forced-air cooling condition with different wind speeds. In addition, the mechanical characteristics are analyzed under no-load and different loads conditions, respectively. All of the results are analyzed by two-dimension (2-D and three-dimension (3-D finite element method (FEM simulation, which provide a good reference to select suitable power level for this kind of motor structure. Finally, a DRPMSM prototype is manufactured and tested. The experimental results effectively verify the FEM results.

  14. Operations of the thermal control system for Alpha Magnetic Spectrometer electronics following the beta angle of the International Space Station

    International Nuclear Information System (INIS)

    The Alpha Magnetic Spectrometer (AMS) has been running and measuring cosmic rays on the International Space Station (ISS) since May 19, 2011. The thermal control system (TCS) plays an important role in keeping all components and equipment working in an operational temperature range. Since the AMS started working on the ISS, AMS thermal engineers have been monitoring the on-orbit status of the TCS. During normal operation, the local temperature of AMS components regularly varies along with the β angle of the ISS. Based on the collected temperature data, the general characteristics of local temperature variations of TCS for AMS Electronics following the β of the ISS are discussed with the statistics of the orbit-averaged temperature and the orbit standard deviation of temperature. Furthermore some temperature anomalies at specific β are also studied. - Highlights: • The variation of the main radiators temperature is statistically analyzed. • The hot case and cold case for the main radiators are found in normal operations. • The solar illumination falling on the inner sheet of RAM radiator leads to temperature jump. • The temperature anomalies on the WAKE radiator show a uniform trend except WR3 sensor. • The regularity of the temperature variation is described with fitted equations

  15. Instability growth for magnetized liner inertial fusion seeded by electro-thermal, electro-choric, and material strength effects

    International Nuclear Information System (INIS)

    A critical limitation of magnetically imploded systems such as magnetized liner inertial fusion (MagLIF) [Slutz et al., Phys. Plasmas 17, 056303 (2010)] is the magneto-Rayleigh-Taylor (MRT) instability which primarily disrupts the outer surface of the liner. MagLIF-relevant experiments have showed large amplitude multi-mode MRT instability growth growing from surface roughness [McBride et al., Phys. Rev. Lett. 109, 135004 (2012)], which is only reproduced by 3D simulations using our MHD code Gorgon when an artificially azimuthally correlated initialisation is added. We have shown that the missing azimuthal correlation could be provided by a combination of the electro-thermal instability (ETI) and an “electro-choric” instability (ECI); describing, respectively, the tendency of current to correlate azimuthally early in time due to temperature dependent Ohmic heating; and an amplification of the ETI driven by density dependent resistivity around vapourisation. We developed and implemented a material strength model in Gorgon to improve simulation of the solid phase of liner implosions which, when applied to simulations exhibiting the ETI and ECI, gave a significant increase in wavelength and amplitude. Full circumference simulations of the MRT instability provided a significant improvement on previous randomly initialised results and approached agreement with experiment

  16. Joining time-resolved thermometry and magnetic-induced heating in a single nanoparticle unveils intriguing thermal properties.

    Science.gov (United States)

    Piñol, Rafael; Brites, Carlos D S; Bustamante, Rodney; Martínez, Abelardo; Silva, Nuno J O; Murillo, José L; Cases, Rafael; Carrey, Julian; Estepa, Carlos; Sosa, Cecilia; Palacio, Fernando; Carlos, Luís D; Millán, Angel

    2015-03-24

    Whereas efficient and sensitive nanoheaters and nanothermometers are demanding tools in modern bio- and nanomedicine, joining both features in a single nanoparticle still remains a real challenge, despite the recent progress achieved, most of it within the last year. Here we demonstrate a successful realization of this challenge. The heating is magnetically induced, the temperature readout is optical, and the ratiometric thermometric probes are dual-emissive Eu(3+)/Tb(3+) lanthanide complexes. The low thermometer heat capacitance (0.021·K(-1)) and heater/thermometer resistance (1 K·W(-1)), the high temperature sensitivity (5.8%·K(-1) at 296 K) and uncertainty (0.5 K), the physiological working temperature range (295-315 K), the readout reproducibility (>99.5%), and the fast time response (0.250 s) make the heater/thermometer nanoplatform proposed here unique. Cells were incubated with the nanoparticles, and fluorescence microscopy permits the mapping of the intracellular local temperature using the pixel-by-pixel ratio of the Eu(3+)/Tb(3+) intensities. Time-resolved thermometry under an ac magnetic field evidences the failure of using macroscopic thermal parameters to describe heat diffusion at the nanoscale. PMID:25693033

  17. Instability growth for magnetized liner inertial fusion seeded by electro-thermal, electro-choric, and material strength effects

    Energy Technology Data Exchange (ETDEWEB)

    Pecover, J. D.; Chittenden, J. P. [The Centre for Inertial Fusion Studies, The Blackett Laboratory, Imperial College, London SW7 2AZ (United Kingdom)

    2015-10-15

    A critical limitation of magnetically imploded systems such as magnetized liner inertial fusion (MagLIF) [Slutz et al., Phys. Plasmas 17, 056303 (2010)] is the magneto-Rayleigh-Taylor (MRT) instability which primarily disrupts the outer surface of the liner. MagLIF-relevant experiments have showed large amplitude multi-mode MRT instability growth growing from surface roughness [McBride et al., Phys. Rev. Lett. 109, 135004 (2012)], which is only reproduced by 3D simulations using our MHD code Gorgon when an artificially azimuthally correlated initialisation is added. We have shown that the missing azimuthal correlation could be provided by a combination of the electro-thermal instability (ETI) and an “electro-choric” instability (ECI); describing, respectively, the tendency of current to correlate azimuthally early in time due to temperature dependent Ohmic heating; and an amplification of the ETI driven by density dependent resistivity around vapourisation. We developed and implemented a material strength model in Gorgon to improve simulation of the solid phase of liner implosions which, when applied to simulations exhibiting the ETI and ECI, gave a significant increase in wavelength and amplitude. Full circumference simulations of the MRT instability provided a significant improvement on previous randomly initialised results and approached agreement with experiment.

  18. Airborne lidar detection of subsurface oceanic scattering layers

    Science.gov (United States)

    Hoge, Frank E.; Wright, C. Wayne; Krabill, William B.; Buntzen, Rodney R.; Gilbert, Gary D.

    1988-01-01

    The airborne lidar detection and cross-sectional mapping of submerged oceanic scattering layers are reported. The field experiment was conducted in the Atlantic Ocean southeast of Assateague Island, VA. NASA's Airborne Oceanographic Lidar was operated in the bathymetric mode to acquire on-wavelength 532-nm depth-resolved backscatter signals from shelf/slope waters. Unwanted laser pulse reflection from the air-water interface was minimized by spatial filtering and off-nadir operation. The presence of thermal stratification over the shelf was verified by the deployment of airborne expendable bathythermographs. Optical beam transmission measurements acquired from a surface truthing vessel indicated the presence of a layer of turbid water near the sea floor over the inner portion of the shelf.

  19. Transport of thermal energy and its relation to magnetic reconnection and to the spontaneous rotation phenomenon

    International Nuclear Information System (INIS)

    The high-temperature theory of the collisional drift-tearing mode is presented. In the regimes relevant to present day experiments the parallel electron thermal conductivity plays a key role and the novel analysis that is presented shows that the structure of the mode as well as the characteristics of the region where reconnection takes place differ significantly from the ones described in the original work where the regime with relatively high collisionality was considered. A brief description is given of the 'accretion' theory of the 'spontaneous' rotation phenomenon and of the associated toroidal plasma collective modes that produce an inflow of angular momentum towards the center of the plasma column. (author)

  20. The Effect of Blood Flow on Magnetic Resonance Imaging of Non Thermal Irreversible Electroporation

    OpenAIRE

    Mohammad Hjouj; Jacob Lavee; David Last; David Guez; Dianne Daniels; Shirley Sharabi; Boris Rubinsky; Yael Mardor

    2013-01-01

    To generate an understanding of the physiological significance of MR images of Non-Thermal Irreversible Electroporation (NTIRE) we compared the following MR imaging sequences: T1W, T2W, PD, GE, and T2 SPAIR acquired after NTIRE treatment in a rodent liver model. The parameters that were studied included the presence or absence of a Gd-based contrast agent, and in vivo and ex-vivo NTIRE treatments in the same liver. NTIRE is a new minimally invasive tissue ablation modality in which pulsed ele...

  1. Generation of non-equilibrium thermal quantum discord and entanglement in a three-spin XX chain by multi-spin interaction and an external magnetic field

    International Nuclear Information System (INIS)

    The generation of non-equilibrium thermal quantum discord and entanglement is investigated in a three-spin chain whose two end spins are respectively coupled to two thermal reservoirs at different temperatures. We show that the spin chain can be decoupled from the thermal reservoirs by homogeneously applying a magnetic field and including a strong three-spin interaction, and then the maximal steady-state quantum discord and entanglement in the two end spins can always be created. In addition, the present investigation may provide a useful approach to control coupling between a quantum system and its environment. -- Highlights: → Spin chain decoupled from thermal reservoirs. → Thermal excitation depressed. → Maximal quantum correlations created.

  2. Modeling for Airborne Contamination

    International Nuclear Information System (INIS)

    The objective of Modeling for Airborne Contamination (referred to from now on as ''this report'') is to provide a documented methodology, along with supporting information, for estimating the release, transport, and assessment of dose to workers from airborne radioactive contaminants within the Monitored Geologic Repository (MGR) subsurface during the pre-closure period. Specifically, this report provides engineers and scientists with methodologies for estimating how concentrations of contaminants might be distributed in the air and on the drift surfaces if released from waste packages inside the repository. This report also provides dose conversion factors for inhalation, air submersion, and ground exposure pathways used to derive doses to potentially exposed subsurface workers. The scope of this report is limited to radiological contaminants (particulate, volatile and gaseous) resulting from waste package leaks (if any) and surface contamination and their transport processes. Neutron activation of air, dust in the air and the rock walls of the drift during the preclosure time is not considered within the scope of this report. Any neutrons causing such activation are not themselves considered to be ''contaminants'' released from the waste package. This report: (1) Documents mathematical models and model parameters for evaluating airborne contaminant transport within the MGR subsurface; and (2) Provides tables of dose conversion factors for inhalation, air submersion, and ground exposure pathways for important radionuclides. The dose conversion factors for air submersion and ground exposure pathways are further limited to drift diameters of 7.62 m and 5.5 m, corresponding to the main and emplacement drifts, respectively. If the final repository design significantly deviates from these drift dimensions, the results in this report may require revision. The dose conversion factors are further derived by using concrete of sufficient thickness to simulate the drift

  3. Cytotoxicity Evaluation and Magnetic Characteristics of Mechano-thermally Synthesized CuNi Nanoparticles for Hyperthermia

    Science.gov (United States)

    Amrollahi, P.; Ataie, A.; Nozari, A.; Seyedjafari, E.; Shafiee, A.

    2015-03-01

    CuNi alloys are very well known, both in academia and industry, based on their wide range of applications. In the present investigation, the previously synthesized Cu0.5Ni0.5 nanoparticles (NPs) by mechano-thermal method were studied more extensively. Phase composition and morphology of the samples were studied by employing x-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) techniques. The Curie temperature ( T c) was determined by differential scanning calorimetry (DSC). In vitro cytotoxicity was studied through methyl-thiazolyl-tetrazolium (MTT) assay. XRD and FESEM results indicated the formation of single-phase Cu0.5Ni0.5. TEM micrographs showed that the mean particle size of powders is 20 nm. DSC results revealed that T c of mechano-thermally synthesized Cu0.5Ni0.5 is 44 °C. The MTT assay results confirmed the viability and proliferation of human bone marrow stem cells in contact with Cu0.5Ni0.5 NPs. In summary, the fabricated particles were demonstrated to have potential in low concentrations for cancer treatment applications.

  4. Thermal and hydraulic analyses of TFTR cooling water system and magnetic field coils

    International Nuclear Information System (INIS)

    The TFTR toroidal field coils, ohmic heating, hybrid and equilibrium field coils are cooled by water from the machine area cooling water system. The system has the following major equipment and capacities: flow rate of 3600 gpm; ballast tank volume of 5500 gal; pumps of 70.4 m head; chiller refrigeration rating of 3300 tons and connecting pipe of 45.7 cm I.D. The performance of the closed loop system was analyzed and found to be adequate for the thermal loads. The field coils were analyzed with detailed thermal and hydraulic models, including a simulation of the complete water cooling loop. Under the nominal operating mode of one second of toroidal field flat top time and 300 seconds of pulse cycle time, the maximum temperature for the TF coils is 530C; for the OH coils 460C and for the EF coils 390C, which are well below the coil design limit of 1200C. The maximum TF coil coolant temperature is 330C which is below the coolant design limit of 1000C. The overall pressure loss of the system is below 6.89 x 105 Pa (100 psi). With the given chiller refrigeration capacity, the TF coils can be operated to yield up to 4 seconds of flat top time. The TF coils can be operated on a steady state basis at up to 20% of the pulsed duty design current rating of 7.32 kA/coil

  5. Convection during Thermally Unstable Solidification of Pb-Sn in a Magnetic Field

    Science.gov (United States)

    Song, H.; Tewari, S. N.; DeGroh, H. C., III

    1996-01-01

    Convection and macrosegregation in directionally solidified hypoeutectic Pb-38 wt pct Sn and hypereutectic Pb-64.5 wt pct Sn have been examined during upward and downward growth. Temperature fluctuations are observed along the length of the melt column during downward growth. With increasing Rayleigh number, these fluctuations change from none, to cyclic, to time periodic having multiple harmonics, and finally to random. At the higher convective driving force of 350 K temperature inversion, the transverse magnetic field decreased convective levels, strong random temperature fluctuations (flows) becoming smaller and periodic. The maximum field of 0.45 T was unable to completely eliminate convection. For the lower convective driving force of 150 K temperature inversion, the 0.05 T magnetic field decreased flows, and at 0.15 T, the field caused a dramatic decrease in the characteristic frequency of the temperature fluctuations, indicating a change in the nature of the flow, the waveform of the temperature fluctuations changing from sinusoidal to a pulsed wave. Temperature fluctuations and time delays between thermocouples were used to estimate flow velocities. Irrespective of the convection in the bulk melt (ahead of the mushy zone), longitudinal macrosegregation occurs only if the interdendritic melt mixes with the bulk melt.

  6. INFLUENCE OF TECHNOLOGICAL MODES OF MAGNETIC-ELECTRIC GRINDING ON MICROSTRUCTURE OF GAS-THERMAL SPRAYED NI–CR–B–SI-COATINGS

    Directory of Open Access Journals (Sweden)

    N. V. Spiridonov

    2009-01-01

    Full Text Available Influence of technological modes of magnetic-electric grinding on structural changes in a surface layer of gas-thermal sprayed coatings is investigated in the paper. The paper presents optimum modes of  coating roughing and finishing processes.

  7. Coercivity and thermal stability improvement in sintered Nd-Fe-B permanent magnets by intergranular addition of Dy-Mn alloy

    Science.gov (United States)

    Li, Xiangbin; Liu, Shuo; Cao, Xuejing; Zhou, Beibei; Chen, Ling; Yan, Aru; Yan, Gaolin

    2016-06-01

    To increase coercivity and thermal stability of sintered Nd-Fe-B magnets for high temperature applications, Dy88Mn12 (wt%) alloy powders were intergranular added into (Pr0.25Nd0.75)30.6Cu0.15FebalB1 (wt%) starting magnet. The magnetic properties, microstructure and thermal stability of the sintered magnets with different amounts of Dy88Mn12 were investigated. By adding a small amount of Dy88Mn12, the coercivity was significantly increased from 12.56 kOe to 17.49 kOe. Microstructure analysis showed that a optimized microstructure, i.e. continuous, uniform grain boundary phase was achieved with Dy88Mn12 alloy addition, and Dy was enriched in the outer region of the Nd2Fe14B matrix grains during the sintering process, which favored to substitute for Nd in matrix grains to form the (Nd,Dy)2Fe14B core-shell phase. The greatly increased magnetocrystalline anisotropy of the core-shell phase and the improved decoupling by the continuous grain boundary phase accounted for the coercivity enhancement. Furthermore, by adding 0-4 wt% Dy88Mn12, the reversible temperature coefficients of remanence (α) and coercivity (β) of the magnet were improved from -0.115%/ºC to -0.107%/ºC and -0.744%/ºC to -0.696%/ºC in the range of 20-100 °C, respectively. In addition, the irreversible flux loss of magnetic flow (hirr) decreased sharply as Dy88Mn12 addition. The temperature-dependent magnetic properties results indicated that with intergranular addition of Dy88Mn12 alloy, the thermal stability of the magnets was effectively improved.

  8. Soft magnetic properties and thermal stability of bulk Fe83B17 alloy prepared by undercooling and Cu-mold casting methods

    International Nuclear Information System (INIS)

    The thermal stability and soft magnetic properties of bulk Fe83B17 rods with nano-lamellar eutectic structures and metastable Fe3B phases were investigated by annealing at 973–1273 K for 1.5 h. Samples with a diameter of 3 mm were prepared by undercooling solidification combined with Cu-mold casting. The decomposition of Fe3B and the transformation of nano-lamellar eutectic structures were finished after annealing at 1173 K for 1.5 h. Increasing annealing temperature showed that the soft magnetic properties of the sample were kept relatively stable. The saturation magnetization and retentivity were decreased only slightly, while the coercivity was decreased significantly. - Highlights: • Thermal stability of the nano-lamellar eutectic structure was obtained. • Thermal stability of the metastable Fe3B phase was obtained. • The soft magnetic properties of the sample remain stability by annealing. • Nano-lamellar eutectic structures enhance the soft magnetic properties

  9. MAGNET

    CERN Multimedia

    by B. Curé

    2011-01-01

    The magnet operation was very satisfactory till the technical stop at the end of the year 2010. The field was ramped down on 5th December 2010, following the successful regeneration test of the turbine filters at full field on 3rd December 2010. This will limit in the future the quantity of magnet cycles, as it is no longer necessary to ramp down the magnet for this type of intervention. This is made possible by the use of the spare liquid Helium volume to cool the magnet while turbines 1 and 2 are stopped, leaving only the third turbine in operation. This obviously requires full availability of the operators to supervise the operation, as it is not automated. The cryogenics was stopped on 6th December 2010 and the magnet was left without cooling until 18th January 2011, when the cryoplant operation resumed. The magnet temperature reached 93 K. The maintenance of the vacuum pumping was done immediately after the magnet stop, when the magnet was still at very low temperature. Only the vacuum pumping of the ma...

  10. Airborne Cloud Computing Environment (ACCE)

    Science.gov (United States)

    Hardman, Sean; Freeborn, Dana; Crichton, Dan; Law, Emily; Kay-Im, Liz

    2011-01-01

    Airborne Cloud Computing Environment (ACCE) is JPL's internal investment to improve the return on airborne missions. Improve development performance of the data system. Improve return on the captured science data. The investment is to develop a common science data system capability for airborne instruments that encompasses the end-to-end lifecycle covering planning, provisioning of data system capabilities, and support for scientific analysis in order to improve the quality, cost effectiveness, and capabilities to enable new scientific discovery and research in earth observation.

  11. Thermal expansion studies on low-dimensional frustrated quantum magnets. The case of κ-(BEDT-TTF)2Cu2(CN)3 and azurite

    International Nuclear Information System (INIS)

    Thermal expansion measurements provide a sensitive tool for exploring a material's thermodynamic properties in condensed matter physics as they provide useful information on the electronic, magnetic and lattice properties of a material. In this thesis, thermal expansion measurements have been carried out both at ambient-pressure and under hydrostatic pressure conditions. From the materials point of view, the spin-liquid candidate κ-(BEDT-TTF)2Cu2(CN)3 has been studied extensively as a function of temperature and magnetic field. Azurite, Cu3(CO3)2(OH)2 - a realization of a one-dimensional distorted Heisenberg chain is also studied both at ambient and hydrostatic pressure to demonstrate the proper functioning of the newly built setup ''thermal expansion under pressure''.

  12. The Effect of Blood Flow on Magnetic Resonance Imaging of Non Thermal Irreversible Electroporation

    Science.gov (United States)

    Hjouj, Mohammad; Lavee, Jacob; Last, David; Guez, David; Daniels, Dianne; Sharabi, Shirley; Rubinsky, Boris; Mardor, Yael

    2013-10-01

    To generate an understanding of the physiological significance of MR images of Non-Thermal Irreversible Electroporation (NTIRE) we compared the following MR imaging sequences: T1W, T2W, PD, GE, and T2 SPAIR acquired after NTIRE treatment in a rodent liver model. The parameters that were studied included the presence or absence of a Gd-based contrast agent, and in vivo and ex-vivo NTIRE treatments in the same liver. NTIRE is a new minimally invasive tissue ablation modality in which pulsed electric fields cause molecularly selective cell death while, the extracellular matrix and large blood vessels remain patent. This attribute of NTIRE is of major clinical importance as it allows treatment of undesirable tissues near critical blood vessels. The presented study results suggest that MR images acquired following NTIRE treatment are all directly related to the unique pattern of blood flow after NTIRE treatment and are not produced in the absence of blood flow.

  13. Recovering metals from red mud by thermal treatment and magnetic separation

    Science.gov (United States)

    Plescia, Paolo; Maccari, Dante

    1996-01-01

    This paper deals with an alternative treatment for recovering metals from goethite red mud (RM), which occurs as a by-product at zinc leaching plants. It is derived from the hydrometallurgical treatment of sphalerite, which involves roasting followed by acid attack and subsequent recovery of the zinc by electrodeposition. The leaching mud contains various oxides and hydroxides of iron plus lesser amounts of sulfates of Pb, Zn, Ca, Cd, Ag, In, Se, and other metals. In recent years, numerous attempts have been made to recover the RM or render it inert, particularly by such processes as vitrification or lithification for the production of glass ceramics. The work reported here proposes a treatment involving reduction and magnetic separation to permit the extraction of pure zinc, a high percentage of a pure magnetite, and a harmless slag containing mixed silicates of zinc and lead as well as oxides of minor elements.

  14. Magnetic Attitude Control System for a Small Satellite. Impact on the Thermal Performance

    OpenAIRE

    Farrahi, Assal

    2015-01-01

    El principal objetivo de la tesis es estudiar el acoplamiento entre los subsistemas de control de actitud y de control térmico de un pequeño satélite, con el fin de buscar la solución a los problemas relacionados con la determinación de los parámetros de diseño. Se considera la evolución de la actitud y de las temperaturas del satélite bajo la influencia de dos estrategias de orientación diferentes: 1) estabilización magnética pasiva de la orientación (PMAS, passive magnetic attitude stabiliz...

  15. Structural support of a yin-yang magnet for a tandem mirror reactor with thermal barriers

    International Nuclear Information System (INIS)

    This report contains a comprehensive summary covering work performed by Grumman Aerospace Corporation, in conjunction with the Lawrence Livermore National Laboratory, on the TMP yin-yang coils. The yin-yang coil pair used for our analysis has a major arc radius of 2.7 m and a minor arc radius of 1.18 m, compared with 2.5 m and 0.75 m for the MFTF. The maximum field on the present conductor is 9.05 Tesla. This magnetic field is created by, and interacts with, a conductor current which produces a 360 million Newton total force, tending to separate the parallel lobes of the major arcs

  16. Mapping permafrost with airborne electromagnetics

    Science.gov (United States)

    Minsley, B. J.; Ball, L. B.; Bloss, B. R.; Kass, A.; Pastick, N.; Smith, B. D.; Voss, C. I.; Walsh, D. O.; Walvoord, M. A.; Wylie, B. K.

    2014-12-01

    Permafrost is a key characteristic of cold region landscapes, yet detailed assessments of how the subsurface distribution of permafrost impacts the environment, hydrologic systems, and infrastructure are lacking. Data acquired from several airborne electromagnetic (AEM) surveys in Alaska provide significant new insight into the spatial extent of permafrost over larger areas (hundreds to thousands of square kilometers) than can be mapped using ground-based geophysical methods or through drilling. We compare several AEM datasets from different areas of interior Alaska, and explore the capacity of these data to infer geologic structure, permafrost extent, and related hydrologic processes. We also assess the impact of fires on permafrost by comparing data from different burn years within similar geological environments. Ultimately, interpretations rely on understanding the relationship between electrical resistivity measured by AEM surveys and the physical properties of interest such as geology, permafrost, and unfrozen water content in the subsurface. These relationships are often ambiguous and non-unique, so additional information is useful for reducing uncertainty. Shallow (upper ~1m) permafrost and soil characteristics identified from remotely sensed imagery and field observations help to constrain and aerially extend near-surface AEM interpretations, where correlations between the AEM and remote sensing data are identified using empirical multivariate analyses. Surface nuclear magnetic resonance (sNMR) measurements quantify the contribution of unfrozen water at depth to the AEM-derived electrical resistivity models at several locations within one survey area. AEM surveys fill a critical data gap in the subsurface characterization of permafrost environments and will be valuable in future mapping and monitoring programs in cold regions.

  17. Structure, thermal and magnetic properties of Fe43Co14Ni14B20Si5Nb4 bulk metallic glass

    Directory of Open Access Journals (Sweden)

    R. Nowosielski

    2010-02-01

    Full Text Available Purpose: The paper presents structure characteristics, thermal stability and soft magnetic properties analysis of Fe-based bulk metallic glass in as-cast state and after crystallization process.Design/methodology/approach: The studies were performed on Fe43Co14Ni14B20Si5Nb4 metallic glass in a form of plates and rods. The amorphous structure of tested samples was examined by X-ray diffraction (XRD, transmission electron microscopy (TEM and scanning electron microscopy (SEM methods. The thermal stability of the glassy samples was measured using differential scanning calorimetry (DSC. The soft magnetic properties examination of tested material contained initial magnetic permeability and magnetic permeability relaxation measurements.Findings: The XRD and TEM investigations revealed that the studied as-cast plates and rods were amorphous. Broad diffraction halo could be observed for all tested samples, indicating the formation of a glassy phase with the diameters up to 3 mm for rods. The fracture surface of rod samples appears to consist of two different zones which might correspond with different amorphous structures of studied materials. The thermal stability parameters of rod with diameter of 3 mm, such as glass transition temperature, onset crystallization temperature and supercooled liquid area were measured by DSC to be 797 K, 854 K, 57 K, respectively. The heat treatment process of rod samples involved in crystallization of α-Fe phase and formation of iron borides at temperature above 873 K.Practical implications: The appropriate increase of annealing temperature significantly improved soft magnetic properties of examined alloy by increasing the initial magnetic permeability and decreasing the magnetic permeability relaxation.Originality/value: The success of fabrication of studied Fe-based bulk metallic glass in a form of plates and rods is important for the future progress in research and practical application of those glassy materials.

  18. 3-D Thermal, Hydrodynamic and Magnetic Modelling of Elaboration of Glass by Induction in Cold Crucible

    International Nuclear Information System (INIS)

    The Vitrification of high-level liquid waste produced from nuclear fuel reprocessing has been carried out industrially for more than 30 years by AREVA, with three main objectives: containment of the long lived fission products, reduction of the final volume of waste and operability in an industrial context. In parallel the French Atomic Energy Commission (CEA), SGN (respectively Areva's R and D provider and Engineering) and AREVA (industrial Operator) have developed the cold crucible induction melter vitrification technology to obtain greater operating flexibility, increased plant availability and further reduction of secondary waste generated during operations. The 3D numerical simulation of elaboration of glass by induction in cold crucible needs a coupled approach of the different phenomena: induction, thermal and hydrodynamic. Indeed, those three phenomena are strongly coupled because of the temperature dependence of the glass properties. The hotter the molten glass, the higher the electrical conductivity. In the present paper, we will focus on a full 3D simulation, when mechanical stirrer and bubbling are stopped in the cold crucible melter. In this case, the convection is driven by two phenomena. First, buoyancy forces are modelled in the Boussinesq approximation. Second, thermo capillary convection at the surface is taken into account. This effect is due to the variation of the surface tension with the temperature. Thermo convective circulations appear within the molten glass when the total Joule power injected reached a specific threshold. (authors)

  19. Thermal-shock- and fatigue-resistant coatings for magnetically confined fusion environments

    International Nuclear Information System (INIS)

    Candidate coating systems of materials of low atomic number Z under development for fusion reactor applications were exposed to a maximum of 1000 cycles of electron beam pulse heating at 2 kW cm-2 for 1.5 s. The coating/substrate systems that were investigated include chemically vapor-deposited TiB2/graphite, chemically vapor-deposited TiC/graphite, chemically vapor-deposited B/graphite, plasma-sprayed TiB2/Cu, clad V/Cu, clad Ti/Cu and clad plus borided VB2/V/Cu. All the thin coatings obtained by chemical vapor deposition (CVD) survived the testing as did the plasma-sprayed TiB2/Cu. coatings of CVD TiB2 and CVD TiC on Poco graphite showed fatigue cracking which may have propagated into the graphite substrates. Some of the clad materials showed failure due to coating melt and deformation and separation due to thermal ratcheting. (Auth.)

  20. Preparation, thermal stability, and magnetic properties of Fe-Zr-Mo-W-B bulk metallic glass

    International Nuclear Information System (INIS)

    A bulk metallic glass (BMG) cylinder of Fe60Co8Zr10Mo5W2B15 with a diameter of 1.5 mm was prepared by copper mould casting of industrial raw materials. The amorphous state and the crystallization behavior were investigated by X-ray diffraction (XRD). The thermal stability parameters, such as glass transition temperature (Tg), crystallization temperature (Tx), supercooled liquid region (ΔTx) between Tg and Tx, and reduced glass transition temperature Trg (Tg/Tm) were measured by differential scanning calorimetry (DSC) to be 891, 950, 59 K, and 0.62, respectively. The crystallization process took place through a single stage, and involved crystallization of the phases α-Fe, ZrFe2, Fe3B, MoB2, Mo2FeB2, and an unknown phase, as determined by X-ray analysis of the sample annealed for 1.5 ks at 1023 K, 50 K above the DSC peak temperature of crystallization. Moessbauer spectroscopy was studied for this alloy. The spectra exhibit a broadened and asymmetric doublet-like structure that indicated paramagnetic behavior and a fully amorphous structure. α-Fe was found in the amorphous matrix for a cylinder with a diameter of 2.5 mm. The success of synthesis of the Fe-based bulk metallic glass from industrial materials is important for the future progress in research and practical application of new bulk metallic glasses